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FEATURES
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LTC4066/LTC4066-1 USB Power Controller and Li-Ion Linear Charger with Low Loss Ideal Diode DESCRIPTION
The LTC(R)4066/LTC4066-1 are USB power managers and Li-Ion battery chargers designed to work in portable battery-powered applications. The parts control the total current used by the USB peripheral for operation and battery charging. The total input current can be limited to 100mA, 500mA or "unlimited" (i.e., above 2A). Battery charge current is automatically reduced such that the sum of the load current and the charge current does not exceed the programmed input current limit. The LTC4066/LTC4066-1 include a standalone constantcurrent/constant-voltage linear charger for single cell Li-ion batteries. The float voltage applied to the battery is held to a tight 0.8% tolerance, and charge current is programmable using an external resistor to ground. A programmable end-of-charge status output (CHRG) indicates full charge. BAT pin charge and discharge currents can be monitored via an analog output (ISTAT). Total charge time is programmable by an external capacitor to ground. When the battery drops 100mV below the float voltage, automatic recharging of the battery occurs. Also featured is an NTC thermistor input used to monitor battery temperature while charging. The LTC4066/LTC4066-1 are available in a 24-pin thin profile (0.75mm) 4mm x 4mm QFN package. The LTC4066 is also available in a 24-pin ultrathin profile (0.55mm) 4mm x 4mm UTQFN package.
L, LT, LTC and LTM are registered trademarks of Linear Technology Corporation. PowerPath is a trademark of Linear Technology Corporation. All other trademarks are the property of their respective owners. *Protected by U.S. Patents including 6522118.
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Seamless Transition Between Input Power Sources: Li-Ion Battery, USB and 5V Wall Adapter Low Loss (50m) Ideal Diode Path from BAT to OUT Programmable Charge Current Detection (CHRG) Load Dependent Charging Guarantees USB Input Current Compliance Analog Gas Gauge Function Charges Single Cell Li-Ion Batteries Directly from USB Port Constant-Current/Constant-Voltage Operation with Thermal Feedback to Maximize Charging Rate Without Risk of Overheating* Selectable 100% or 20% Current Limit (e.g., 500mA/100mA) Termination Timer Adapts to Actual Charge Current Preset 4.2V Charge Voltage with 0.8% Accuracy (4.1V for LTC4066-1) NTC Thermistor Input for Temperature Qualified Charging Thin Profile (0.75mm) 24-Lead 4mm x 4mm QFN Package Ultrathin Profile (0.55mm) 24-Lead 4mm x 4mm UTQFN Package (LTC4066 Only)
APPLICATIONS
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Portable USB Devices GPS, Cameras, Broadband Wireless Modems Mulitple Input Chargers
TYPICAL APPLICATION
5V (NOM) FROM USB CABLE VBUS IN 4.7F VNTC NTC WALL SHDN SUSPEND USB POWER 500mA/100mA SELECT INPUT CURRENT LIMIT DISABLE 0.1F SUSP HPWR CLDIS TIMER PROG CLPROG 2k OUT BAT CURRENT (mA)
600 500 400 ILOAD 300 200 100 TO ADC FOR GAS GAUGE 0 -100 IIN
+
510
510
TO LDOs, REGs, ETC 4.7F
LTC4066
CHRG ACPR POL ISTAT GND 2k
4066 TA01
IBAT CHARGING
100k
0
100
200
300 400 ILOAD (mA)
500
600 IBAT (IDEAL DIODE)
4066 TA02
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LTC4066/LTC4066-1 ABSOLUTE MAXIMUM RATINGS
(Notes 1 to 6)
Terminal Voltage t < 1ms and Duty Cycle < 1% IN, OUT ................................................... -0.3V to 7V Steady State IN, OUT, BAT ........................................... -0.3V to 6V NTC, VNTC, TIMER, PROG, CLPROG, ISTAT ....................... -0.3V to (VCC + 0.3V) CHRG, HPWR, SUSP SHDN, , WALL, ACPR, POL, CLDIS ...................... -0.3V to 6V
Pin Current (DC) IN (Note 7) .......................................................... 2.7A OUT, BAT (Note 7) .................................................. 5A Operating Temperature Range................. -40C to 85C Maximum Operating Junction Temperature ......... 125C Storage Temperature Range.................. -65C to 125C
PIN CONFIGURATION
TOP VIEW CLPROG TIMER PROG WALL ISTAT ISTAT POL TOP VIEW CLPROG TIMER PROG WALL POL 18 CHRG 17 ACPR 25 16 GND 15 VNTC 14 NTC 13 HPWR 7 NC 8 OUT 9 10 11 12 IN CLDIS SUSP SHDN
24 23 22 21 20 19 OUT 1 BAT 2 OUT 3 BAT 4 BAT 5 NC 6 7 NC 8 OUT 9 10 11 12 IN CLDIS SUSP SHDN 25 18 CHRG 17 ACPR 16 GND 15 VNTC 14 NTC 13 HPWR OUT 1 BAT 2 OUT 3 BAT 4 BAT 5 NC 6
24 23 22 21 20 19
UF PACKAGE 24-LEAD (4mm 4mm) PLASTIC QFN TJMAX = 125C, JA = 37C/W EXPOSED PAD (PIN #) IS GND, MUST BE SOLDERED TO PCB
PF PACKAGE 24-LEAD (4mm 4mm) PLASTIC UTQFN TJMAX = 125C, JA = 37C/W EXPOSED PAD (PIN #) IS GND, MUST BE SOLDERED TO PCB
ORDER INFORMATION
LEAD FREE FINISH LTC4066EUF#PBF LTC4066EUF-1#PBF LTC4066EPF#PBF TAPE AND REEL LTC4066EUF#TRPBF LTC4066EUF-1#TRPBF LTC4066EPF#TRPBF PART MARKING 4066 40661 4066T PACKAGE DESCRIPTION 24-Lead (4mm x 4mm) Plastic QFN 24-Lead (4mm x 4mm) Plastic QFN 24-Lead (4mm x 4mm) Plastic UTQFN TEMPERATURE RANGE -40C to 85C -40C to 85C -40C to 85C
Consult LTC Marketing for parts specified with wider operating temperature ranges. Consult LTC Marketing for information on non-standard lead based finish parts. For more information on lead free part marking, go to: http://www.linear.com/leadfree/ For more information on tape and reel specifications, go to: http://www.linear.com/tapeandreel/
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LTC4066/LTC4066-1 ELECTRICAL CHARACTERISTICS
SYMBOL VIN VBAT IIN PARAMETER Input Supply Voltage Input Voltage Input Supply Current
The l denotes the specifications which apply over the full operating temperature range, otherwise specifications are at TA = 25C. VIN = 5V, VBAT = 3.7V, HPWR = 5V, WALL = 0V, RPROG = 100k, RCLPROG = RISTAT = 2k, unless otherwise noted.
CONDITIONS IN and OUT BAT IBAT = IISTAT = 0 (Note 8) Suspend Mode; SUSP = 2V Suspend Mode; SUSP = 2V, Wall = 2V, VOUT = 4.8V Shutdown; SHDN = 2V VOUT = 5V, VIN = 0V, VBAT = 4.3V, TIMER = 0V VBAT = 4.3V, Charging Stopped Suspend Mode; SUSP = 2V Shutdown; SHDN = 2V VIN = 0V, BAT Powers OUT, No Load (Note 9) VIN Powers Part, Rising Threshold VOUT Powers Part, Rising Threshold VIN Rising - VIN Falling or VOUT Rising - VOUT Falling RCLPROG = 2k, HPWR = 5V RCLPROG = 2k, HPWR = 0V HPWR = 5V, 400mA Load HPWR = 0V, 80mA Load RCLPROG = 2k RCLPROG = 1k IN or OUT (VIN - VOUT) VIN Rising (VIN - VOUT) VIN Falling (0C to 85C), IBAT = 2mA IBAT = 2mA (0C to 85C), IBAT = 2mA (LTC4066-1) IBAT = 2mA (LTC4066-1) RPROG = 100k, No Load RPROG = 50k, No Load (Note 9) RPROG = 100k RPROG = 50k IBAT = 50mA IBAT = 100mA IBAT = 500mA IBAT = 1000mA VBAT = VFLOAT (4.2V, 4.1V for LTC4066-1) VBAT = 2V, RPROG = 100k (VOUT - VBAT) High to Low, VBAT = 4V (VOUT - VBAT) Low to High, VBAT = 4V VFLOAT - VRECHRG VBAT = 4.2V (4.1V for LTC4066-1) Percent of Total Charge Time Percent of Total Charge Time, VBAT < 2.8V
l l l l l l l l l l l l l
MIN 4.35
TYP
IOUT BAT
Output Supply Current Battery Drain Current
IIN(MAX) VUVLO VUVLO
Maximum Input Current Limit Input or Output Undervoltage Lockout Input or Output Undervoltage Lockout
1.9 3.6 3.6
0.5 50 50 10 400 15 15 2.5 55 2.6 3.8 3.8 125
MAX 5.5 4.3 1.2 100 100 20 800 27 27 5 100 4 4
UNITS V V mA A A A A A A A A A V V mV
Current Limit Current Limit ILIM RON VCLPROG ISS VALEN ON Resistance VIN to VOUT CLPROG Pin Voltage
l l
475 90
l
0.980 0.980 25 -85 4.165 4.158 4.066 4.059 460 920 0.980 0.980 875 900 925 950 94 35 2.8
Soft-Start Inrush Current Automatic Current Limit Enable Threshold Voltage Battery Charger Regulated Output Voltage VFLOAT
500 100 0.16 0.16 1.000 1.000 10 50 -60 4.200 4.200 4.100 4.100 500 1000 1.5 1.000 1.000 1000 1000 1000 1000 100 50 2.9 60 90 100 50 25
525 110
1.020 1.020 75 -25 4.235 4.242 4.134 4.141 540 1080 1.020 1.020 1125 1100 1075 1050 106 60 3
mA mA V V mA/s mV mV V V V V mA mA A V V mA/mA mA/mA mA/mA mA/mA mV mA V mV mV mV % % %
4066fc
l l l l l l l l l l l l
IBAT IBAT(MAX) VPROG kISTAT
Current Mode Charge Current Maximum Charge Current PROG Pin Voltage Ratio of IBAT (Charging) to ISTAT Pin Current
VEOC ITRIKL VTRIKL VCEN VRECHRG tTIMER
End-of-Charge ISTAT Pin Voltage Trickle Charge Current Trickle Charge Threshold Voltage Charger Enable Threshold Voltage Recharge Battery Threshold Voltage TIMER Accuracy Recharge Time Low-Battery Trickle Charge Time
l
60 -10
130 10
3
LTC4066/LTC4066-1 ELECTRICAL CHARACTERISTICS
SYMBOL TLIM PARAMETER Junction Temperature in Constant Temperature Mode
The l denotes the specifications which apply over the full operating temperature range, otherwise specifications are at TA = 25C. VIN = 5V, VBAT = 3.7V, HPWR = 5V, WALL = 0V, RPROG = 100k, RCLPROG = RISTAT = 2k, unless otherwise noted.
CONDITIONS MIN TYP 105 MAX UNITS C
Ideal Diode Incremental Resistance, VON Regulation RFWD On-Resistance VBAT to VOUT RDIO(ON) Voltage Forward Drop (VBAT - VOUT) VFWD
kDIO,ISTAT VOFF IFWD ID(MAX) Logic VOL VIH VIL IPULLDN VCHG,SD
Ratio of IBAT (Discharging Through Ideal Diode) to ISTAT Pin Current Diode Disable Battery Voltage Load Current Limit for VON Regulation Diode Current Limit
IBAT = 500mA IBAT = 3A IBAT = 5mA IBAT = 200mA IBAT = 2A IBAT = 5mA IBAT = 20mA VBAT = 3.5V
l
10
850 850
3.8 ISINK = 5mA SUSP SHDN, HPWR, CLDIS Pin , SUSP SHDN, HPWR, CLDIS Pin , SUSP SHDN, HPWR, CLDIS ,
l l l
27 45 30 47 95 1000 1000 2.8 2.5 5.2 0.1
50
1150 1150
m m mV mV mV mA/mA mA/mA V A A V V V A V A
Output Low Voltage (CHRG, ACPR, POL) Enable Input High Voltage Enable Input Low Voltage Logic Input Pull-Down Current Charger Shutdown Threshold Voltage on TIMER Charger Shutdown Pull-Up Current on ICHG,SD TIMER Wall Input Threshold Voltage VWALL VWALL,HYS Wall Input Hysteresis Wall Input Leakage Current IWALL NTC VNTC Pin Current IVNTC VNTC Bias Voltage VVNTC NTC Input Leakage Current INTC Cold Temperature Fault Threshold Voltage VCOLD VHOT VDIS Hot Temperature Fault Threshold Voltage NTC Disable Voltage
0.25 0.4
1.2 2
l
0.15 2 1.200 4 1.225 35 0
0.4
VTIMER = 0V VWALL Rising Threshold VWALL Rising - VWALL Falling Threshold VWALL = 1V VVNTC = 2.5V IVNTC = 500A VNTC = 1V Rising Threshold Hysteresis Falling Threshold Hysteresis NTC Input Voltage to GND (Falling) Hysteresis
l l
1.250 50
V mV nA mA V A V V V V mV mV
l
1.5 4.4
l
2.5 3.5 4.85 0 1 0.74 * VVNTC 0.02 * VVNTC 0.29 * VVNTC 0.01 * VVNTC 75 100 125 35
Note 1: Stresses beyond those listed under Absolute Maximum Ratings may cause permanent damage to the device. Exposure to any Absolute Maximum Rating condition for extended periods may affect device reliability and lifetime. Note 2: VCC is the greater of VIN, VOUT or VBAT . Note 3: Pins 1, 3 and 8 (OUT) should be tied together with a low impedance to ensure that the difference between the three pins does not exceed 50mV. Pins 2, 4 and 5 (BAT) should be tied together with a low impedance to ensure that the difference between the three pins does not exceed 50mV. Note 4: All voltage values are with respect to GND. Note 5: This IC includes overtemperature protection that is intended to protect the device during momentary overload conditions. Junction
temperature will exceed 125C when overtemperature protection is active. Continuous operation above the specified maximum operating junction temperature may impair device reliability. Note 6: The LTC4066/LTC4066-1 are guaranteed to meet performance specifications from 0C to 70C. Specifications over the -40C to 85C operating temperature range are assured by design, characterization and correlation with statistical process controls. Note 7: Guaranteed by long term current density limitations. Note 8: Total input current is equal to this specification plus 1.003 x IBAT where IBAT is the charge current. Note 9: Accuracy of programmed current may degrade for currents greater than 1.5A.
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LTC4066/LTC4066-1 TYPICAL PERFORMANCE CHARACTERISTICS
Input Supply Current vs Temperature
900 800 700 600 IIN (A) 500 400 300 200 10 100 0 -50 -25 0 25 50 TEMPERATURE (C) 75 100
4066 G01
Input Supply Current vs Temperature (Suspend Mode)
60 50 40 IIN (A) 30 20 VIN = 5V VBAT = 4.2V RPROG = 100k RCLPROG = 2k SUSP = 5V IBAT (A) 70 60 50 40 30 20 10
Battery Drain Current vs Temperature (BAT Powers OUT, No Load)
VIN = 0V VBAT = 4.2V
VIN = 5V VBAT = 4.2V RPROG = 100k RCLPROG = 2k
0 -50
-25
0 25 50 TEMPERATURE (C)
75
100
4066 G02
0 -50
-25
50 25 0 TEMPERATURE (C)
75
100
4066 G03
Input Current Limit vs Temperature, HPWP = 5V
525 VIN = 5V VBAT = 3.7V RPROG = 100k 515 R CLPROG = 2k 505 110 108 106 104 IIN (mA) IIN (mA) 102 100 98 96 485 94 92 475 -50 -25 0 25 50 TEMPERATURE (C) 75 100
4066 G04
Input Current Limit vs Temperature, HPWR = 0V
VIN = 5V VBAT = 3.7V RPROG = 100k RCLPROG = 2k 1200 1000 800 600 400 200
CLPROG Pin Voltage vs Temperature
VIN = 5V RCLPROG = 2k HPWR = 5V VCLPROG (mV)
495
HPWR = 0V
90 -50
-25
25 50 0 TEMPERATURE (C)
75
100
4066 G05
0 -50
-25
0 25 50 TEMPERATURE (C)
75
100
4066 G06
PROG Pin Voltage vs Temperatrue
1.020 1.015 1.010 VFLOAT (V) VIN = 5V RPROG = 100k 4.300 4.250 4.200 4.150 4.100 4.050 4.000 75 100
4066 G07
VFLOAT Load Regulation
RPROG = 34k TA = 25C 4.220 4.200 LTC4066 VFLOAT (V) 4.180 4.160 4.140 4.120
Battery Regulation (Float) Voltage vs Temperature
VIN = 5V LTC4066
VPROG (V)
1.005
1.000 0.995
LTC4066-1 LTC4066-1 4.100 4.080 -50
0.990 0.985 0.980 -50 -25 50 25 TEMPERATURE (C) 0
0
250
500
750 1000 IBAT (mA)
1250
1500
-25
0 50 25 TEMPERATURE (C)
75
100
4066 G09
4066 G08
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LTC4066/LTC4066-1 TYPICAL PERFORMANCE CHARACTERISTICS
Regulated Output Voltage- Recharge Threshold Voltage vs Temperature
120 115 VFLOAT - VRECHG (mV) 110 RON (m) 105 100 95 90 85 80 -50 -25 50 25 TEMPERATURE (C) 0 75 100
4066 G10
Input RON vs Temperature
225 ILOAD = 400mA 200 175 150 125 100 75 -50 VIN = 5V VIN = 4.5V 500 400 VIN = 5.5V IBAT (mA) 300 200 100 0 -25 0 25 50 TEMPERATURE (C) 75 100
4066 G11
Battery Current and Voltage vs Time (LTC4066)
600 6 5 VBAT AND VCHRG (V) 4 3 2 400mAhr CELL VIN = 5V TA = 25C RPROG = 105k 0 50 100 TIME (MINUTES) 150
4066 G12
VIN = 5V
1 0
Charging from USB, IBAT vs VBAT (LTC4066)
VIN = 5V VOUT = NO LOAD 500 RPROG = 100k RCLPROG = 2k HPWR = 5V 400 T = 25C A IBAT (mA) 300 200 100 0 0 IBAT (mA) 600 120
Charging from USB, Low Power, IBAT vs VBAT (LTC4066)
VIN = 5V VOUT = NO LOAD 100 RPROG = 100k RCLPROG = 2k HPWR = 0V 80 T = 25C A 60 40 20 0 0 1500 1250 1000 IBAT (mA)
Undervoltage Current Limit IBAT vs VOUT
TA = 25C WALL = 2V VBAT = 3.5V
RPROG = 34k 750 RPROG = 50k 500 250 RPROG = 100k 0 4.00
0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 VBAT (V)
4066 G13
0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 VBAT (V)
4066 G14
4.10
4.20 4.30 VOUT (V)
4.40
4.50
4066 G15
Charge Current vs Temperature (Thermal Regulation)
1000 RPROG = 50k 4.0 3.5 750 IBAT (mA) 3.0 2.5 IOUT (A) 500 RPROG = 100k 250 VIN = 5V VBAT = 3.5V JA = 43C/W -25 75 0 25 50 TEMPERATURE (C) 100 125 2.0 1.5
Ideal Diode Current vs Forward Voltage and Temperature
VBAT = 3.7V VIN = 0V 25C 3.5 0C -50C 125C IOUT (A) 75C 3.0 2.5 2.0 1.5 1.0 0.5 0 0 20 40 60 80 100 120 140 160 180 200 VFWD (mV)
4066 G17
Ideal Diode Resistance and Current vs Forward Voltage
4.5 4.0 VBAT = 3.5V VIN = 0V TA = 25C 225 200 175 RESISTANCE (m) 150 125 100 RDIO(ON) RFWD 75 50 25
1.0 0.5 0 0
0 -50
0 20 40 60 80 100 120 140 160 180 200 VFWD (mV)
4066 G18
4066 G16
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LTC4066/LTC4066-1 TYPICAL PERFORMANCE CHARACTERISTICS
ISTAT Pin Current vs Battery Current
1500 IDEAL DIODE 1250 1000 IISTAT (A) 750 500 250 VBAT = 4.2V VIN = 5V TA = 25C RPROG = 34k 2 VBAT = 4.2V VIN = 5V TA = 25C IISTAT (A) 6 CHARGING 8 10 IDEAL DIODE CHARGING
ISTAT Pin Current vs Battery Current (Low Currents)
4
0 -1500 -1000 -500
0 500 IBAT (mA)
1000
1500
0 -10 -8 -6 -4 -2 0 2 IBAT (mA)
4
6
8
10
4006 G19
4066 G20
Input Connect Waveforms
VIN 5V/DIV VOUT 5V/DIV IIN 0.5A/DIV IBAT 0.5A/DIV
4066 G21
Input Disconnect Waveforms
VIN 5V/DIV VOUT 5V/DIV IIN 0.5A/DIV IBAT 0.5A/DIV IIN 0.5A/DIV IBAT 0.5A/DIV VBAT = 3.85V IOUT = 100mA 1ms/DIV
4066 G22
Response to HPWR
HPWR 5V/DIV
VBAT = 3.85V IOUT = 100mA
1ms/DIV
VBAT = 3.85V IOUT = 50mA
1ms/DIV
4066 G23
WALL Connect Waveforms, VIN = 0V
WALL 5V/DIV VOUT 5V/DIV IWALL 0.5A/DIV IBAT 0.5A/DIV
4066 G24
WALL Disconnect Waveforms, VIN = 0V
WALL 5V/DIV VOUT 5V/DIV IWALL 0.5A/DIV IBAT 0.5A/DIV
4066 G25
Respond to Suspend
SUSPEND 5V/DIV VOUT 5V/DIV IIN 0.5A/DIV IBAT 0.5A/DIV
4066 G26
VBAT = 3.85V IOUT = 100mA RPROG = 71.5k
1ms/DIV
VBAT = 3.85V IOUT = 100mA RPROG = 71.5k
1ms/DIV
VBAT = 3.85V IOUT = 50mA
1ms/DIV
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LTC4066/LTC4066-1 TYPICAL PERFORMANCE CHARACTERISTICS
WALL Connect Waveforms, VIN = 5V
WALL 5V/DIV IIN 0.5A/DIV IWALL 0.5A/DIV IBAT 0.5A/DIV WALL 5V/DIV IIN 0.5A/DIV IWALL 0.5A/DIV IBAT 0.5A/DIV
WALL Disconnect Waveforms, VIN = 5V
VBAT = 3.85V IOUT = 100mA RPROG = 71.5k
1ms/DIV
4066 G27
VBAT = 3.85V IOUT = 100mA RPROG = 71.5k
1ms/DIV
4066 G28
PIN FUNCTIONS
OUT (Pins 1, 3, 8): Voltage Output. This pin is used to provide controlled power to a USB device from either USB VBUS (IN) or the battery (BAT) when the USB is not present. This pin can also be used as an input for battery charging when the USB is not present and a wall adapter is applied to this pin. OUT should be bypassed with at least 4.7F to GND. Connect Pins 1, 3 and 8 with a resistance no greater than 10m. BAT (Pins 2, 4, 5): Connect to a single cell Li-Ion battery. This pin is used as an output when charging the battery, and as an input when supplying power to OUT. When the OUT pin potential drops below the BAT pin potential, an ideal diode function connects BAT to OUT and prevents VOUT from dropping more than 50mV below VBAT . A precision internal resistor divider sets the final float (charging) potential on this pin. The internal resistor divider is disconnected when IN and OUT are in undervoltage lockout. Connect Pins 2, 4 and 5 with a resistance no greater than 10m. IN (Pin 9): Input Supply. Connect to USB supply, VBUS. Input current to this pin is limited to either 20% or 100% of the current programmed by the CLPROG pin as determined by the state of the HPWR pin. The input current limit can also be disabled by pulling CLDIS high. Charge current (to BAT pin) supplied through the input is set to the current programmed by the PROG pin but will be limited by the input current limit if charge current is set greater than the input current limit. CLDIS (Pin 10): Current Limit Disable. This logic input is used to disable the input current limit programmed by CLPROG. A voltage greater than 1.2V on the pin will set the current limit to IIN(MAX) (typically 2.6A). A weak pulldown current is internally applied to this pin to ensure it is low at power-up when the input is not being driven externally. SUSP (Pin 11): Suspend Mode Input. Pulling this pin above 1.2V will disable the power path from IN to OUT. The supply current from IN will be reduced to comply with the USB specification for Suspend mode. Both the ability to charge the battery from OUT and the ideal diode function (from BAT to OUT) will remain active. Suspend mode will reset the charge timer if VOUT is less than VBAT while in suspend mode. If VOUT is kept greater than VBAT, such as when a wall adapter is present, the charge timer will not be reset when the part is put in suspend. A weak pull-down current is internally applied to this pin to ensure it is low at power-up when the pin is not being driven externally.
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LTC4066/LTC4066-1 PIN FUNCTIONS
SHDN (Pin 12): Shutdown Input. Pulling this pin greater than 1.2V will disable the entire part and place it in a low supply current mode of operation. All power paths will be disabled. A weak pull-down current is internally applied to this pin to ensure it is enabled at power-up when the pin is not being driven externally. HPWR (Pin 13): High Power Select. This logic input is used to control the input current limit. A voltage greater than 1.2V on the pin will set the input current limit to 100% of the current programmed by the CLPROG pin. A voltage less than 0.4V on the pin will set the input current limit to 20% of the current programmed by the CLPROG pin. A weak pull-down current is internally applied to this pin to ensure it is low at power-up when the pin is not being driven externally. NTC (Pin 14): Input to the NTC Thermistor Monitoring Circuits. Under normal operation, tie a thermistor from the NTC pin to ground and a resistor of equal value from NTC to VNTC. When the voltage on this pin is above 0.74 * VVNTC (Cold, 0C) or below 0.29 * VVNTC (Hot, 50C) the timer is suspended, but not cleared, the charging is disabled and the CHRG pin remains in its former state. When the voltage on NTC comes back between 0.74 * VVNTC and 0.29 * VVNTC, the timer continues where it left off and charging is re-enabled if the battery voltage is below the recharge threshold. There is approximately 3C of temperature hysteresis associated with each of the input comparators. Connect the NTC pin to ground to disable this feature. This will disable all of the LTC4066/LTC4066-1 NTC functions. VNTC (Pin 15): Output Bias Voltage for NTC. A resistor from this pin to the NTC pin will bias the NTC thermistor. GND (Pin 16), Exposed Pad (Pin 25): Ground. The Exposed Pad is ground and must be soldered to the PC board for maximum heat transfer. The Exposed Pad must be electrically connected to the GND pin. ACPR (Pin 17): Wall Adapter Present Output. Active low open-drain output pin. A low on this pin indicates that the wall adapter input comparator has had its input pulled above the input threshold. This feature is disabled if the part is shut down or if no power is present on IN or OUT or BAT (i.e., below UVLO thresholds). CHRG (Pin 18): Open-Drain Charge Status Output. When the battery is being charged, the CHRG pin is pulled low by an internal N-channel MOSFET. When the timer runs out or the charge current drops below a programmable current level or the input supply or output supply is removed, the CHRG pin is forced to a high impedance state. POL (Pin 19): Battery Current Status Polarity Pin. This open-drain output pin indicates whether the current flowing out of the ISTAT pin represents one-thousandth of the current flowing into or out of the BAT pins. The POL pin will pull down when current is flowing out of the BAT pin (i.e., charging) and will assume a high impedance state when current is flowing into the BAT pin (i.e., ideal diode). WALL (Pin 20): Wall Adapter Present Input. Pulling this pin above 1.225V will disconnect the power path from IN to OUT. The ACPR pin will also be pulled low to indicate that a wall adapter has been detected. TIMER (Pin 21): Timer Capacitor. Placing a capacitor, CTIMER, to GND sets the timer period. The timer period is: t TIMER(Hours) = CTIMER * RPROG * 3Hours 0.1F * 100k
Charge time is increased if charge current is reduced due to load current, thermal regulation and current limit selection (HPWR). Shorting the TIMER pin to GND disables the battery charging functions.
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LTC4066/LTC4066-1 PIN FUNCTIONS
CLPROG (Pin 22): Current Limit Program and Input Current Monitor. Connecting a resistor, RCLPROG, to ground programs the input to output current limit. The current limit is programmed as follows: ICL ( A) = 1000 V RCLPROG PROG (Pin 23): Charge Current Program. Connecting a resistor, RPROG, to ground programs the battery charge current. The battery charge current is programmed as follows: ICHG( A) = 50, 000 V RPROG
In USB applications the resistor RCLPROG should be set to no less than 2.1k. The voltage on the CLPROG pin is always proportional to the current flowing through the IN to OUT power path. This current can be calculated as follows: IIN( A) = VCLPROG * 1000 RCLPROG
ISTAT (Pin 24): Battery Current Status Pin. One-thousandth of the current flowing into or out of the BAT pins flows out of this pin. The POL polarity pin indicates which direction current is flowing. If the current flowing into the BAT pins drops below 1mA, then the ISTAT pin will continue to source 1A. The ISTAT pin also programs the charge current level at which the CHRG pin transitions to its high impedance state. When the ISTAT voltage drops below 0.1V while charging in constant voltage mode the CHRG pin will transition to a high impedance state. This corresponds to a BAT current of: IBAT ( A) = 0.1V * 1000 RISTAT
4066fc
10
LTC4066/LTC4066-1 BLOCK DIAGRAM
VBUS 9 IN 1,3,8 OUT 2,4,5 BAT
-+
10 CLDIS CURRENT LIMIT DISABLE CURRENT LIMIT 2A IN ILIM CNTL ENABLE IIN 1000 22 100k CLPROG 1V OUT 25mV IDEAL DIODE
+
CL CURRENT CONTROL
SOFT-START ILIM
-
DIE TEMP 105C
13
HPWR
500mA/100mA 2A
-
TA
+
IN OUT BAT
SOFT-START2 CHARGE CONTROL CHRG
+ -
0.25V
+
CHG
1V
-
23 100k 20 WALL PROG BAT UV
+ + -
VOLTAGE DETECT UVLO BAT UV
- + -
4.1V RECHARGE (4.0V LTC4066-1)
1.25V 17 ACPR
15
VNTC CONTROL LOGIC
RECHRG OSCILLATOR TIMER 21
100k
HOLD TOOCOLD NTCERR RESET
CLK STOP COUNTER
14
0.1V
-
16 GND 12 SHDN 11 SUSP ISTAT 24 2k
4066 BD
+
-
100k
+
NTC
NTC
TOOHOT 0.1V |IBAT| 1000
+
EOC
+
NTC ENABLE 2A 2A
-
+
-
CP 2.9V BATTERY UVLO CHRG
CHARGER CC/CV REGULATOR ENABLE
BAT
POL
19
-
18
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11
LTC4066/LTC4066-1 OPERATION
The LTC4066/LTC4066-1 are complete PowerPathTM controllers for battery-powered USB applications. The LTC4066/LTC4066-1 are designed to receive power from a USB source, a wall adapter or a battery. It can then deliver power to an application connected to the OUT pin and a battery connected to the BAT pin (assuming that an external supply other than the battery is present). Power supplies that have limited current resources (such as USB VBUS supplies) should be connected to the IN pin which has a programmable current limit. Battery charge current will be adjusted to ensure that the sum of the charge current and load current does not exceed the programmed input current limit. An ideal diode function provides power from the battery when output/load current exceeds the input current limit or when input power is removed. Powering the load through the ideal diode instead of connecting the load directly to the battery allows a fully charged battery to remain fully charged until external power is removed. Once external power is removed, the output drops until the ideal diode is forward biased. The forward biased ideal diode will then provide the output power to the load from the battery.
WALL ADAPTER
Furthermore, powering switching regulator loads from the OUT pin (rather than directly from the battery), results in shorter battery charge times. This is due to the fact that switching regulators typically require constant input power. When this power is drawn from the OUT pin voltage (rather than the lower BAT pin voltage) the current consumed by the switching regulator is lower, leaving more current available to charge the battery. The LTC4066/LTC4066-1 also have the ability to receive power from a wall adapter. Wall adapter power can be connected to the output (load side) of the LTC4066/LTC4066-1 through an external device such as a power Schottky or FET, as shown in Figure 1. The LTC4066/LTC4066-1 have the unique ability to use the output, which is powered by the wall adapter, as a path to charge the battery while providing power to the load. A wall adapter comparator on the LTC4066/LTC4066-1 can be configured to detect the presence of the wall adapter and shut off the connection to the USB to prevent reverse conduction out to the USB bus.
PowerPath is a trademark of Linear Technology Corporation.
USB VBUS
9
IN
CURRENT LIMIT CONTROL ENABLE
OUT 1,3,8 LOAD CHRG CONTROL IDEAL DIODE BAT 2,4,5
20
WALL
+ -
1.25V
+
4066 F01
Li-Ion
Figure 1. Simplified Block Diagram--PowerPath
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12
LTC4066/LTC4066-1 OPERATION
Table 1. Operating Modes--PowerPath States Current Limited Input Power (IN to OUT)
WALL PRESENT Y X X X X X N SHUTDOWN X Y X X X X N SUSPEND X X Y X X X N VIN > 3.8V X X X N X X Y VIN > (VOUT + 100mV) X X X X N X Y VIN > (VBAT + 100mV) X X X X X N Y CURRENT LIMIT ENABLED N N N N N N Y
Battery Charger (OUT to BAT)
WALL PRESENT X X X X SHUTDOWN Y X X N SUSPEND X X X X VOUT > 4.35V X N X Y VOUT > (VBAT + 100mV) X X N Y CHARGER ENABLED N N N Y
Ideal Diode (BAT to OUT)
WALL PRESENT X X X X SHUTDOWN Y X X N SUSPEND X X X X VBAT > 2.8V X N X Y VBAT > VOUT X X N Y VIN X X X X DIODE ENABLED N N N Y
Table 2. Operating Modes--Pin Currents vs Programmed Currents (Powered from IN)
PROGRAMMING ICL = ICHG OUTPUT CURRENT IOUT < ICL IOUT = ICL = ICHG IOUT > ICL IOUT < (ICL - ICHG) IOUT > (ICL - ICHG) IOUT = ICL IOUT > ICL IOUT < ICL IOUT > ICL BATTERY CURRENT IBAT = ICHG - IOUT IBAT = 0 IBAT = ICL - IOUT IBAT = ICHG IBAT = ICL - IOUT IBAT = 0 IBAT = ICL - IOUT IBAT = ICL - IOUT IBAT = ICL - IOUT INPUT CURRENT IIN = IQ + ICL IIN = IQ + ICL IIN = IQ + ICL IIN = IQ + ICHG + IOUT IIN = IQ + ICL IIN = IQ + ICL IIN = IQ + ICL IIN = IQ + ICL IIN = IQ + ICL
ICL > ICHG
ICL < ICHG
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Operatinal State Diagram
SHUTDOWN SHUTDOWN * CHARGING DISABLED * ALL SWITCHES OPEN SHDN UVLO * CHARGING DISABLED * BATTERY POWERS VOUT BATTERY > 2.8V LOW BATTERY * CHRG IS HI-Z * BATTERY POWER TO VOUT--DISABLED POWER APPLIED TO VIN VIN POWERS PART WALL ADAPTER PRESENT * CURRENT LIMIT FROM IN TO OUT ENABLED WALL ADAPTER PRESENT VOUT POWERS PART * CURRENT LIMIT FROM IN TO OUT DISABLED * ACPR PULLED LOW BATTERY < 4.1V (4.0V LTC4066-1) VOUT CHARGING BATTERY BATTERY < 2.8V
OPERATION
LTC4066/LTC4066-1
14
(VIN AND VOUT) < UVLO BATTERY < 4.1V (4.0V LTC4066-1) VIN CHARGING BATTERY BATTERY > 4.1V (4.0V LTC4066-1) AND CHARGER TIMED OUT BATTERY > 4.1V (4.0V LTC4066-1) AND CHARGER TIMED OUT * CURRENT LIMIT FROM IN TO OUT ENABLED * BATTERY CHARGING ON * CHRG PULLED LOW WALL ADAPTER PRESENT * CURRENT LIMIT FROM IN TO OUT DISABLED * BATTERY CHARGING ON * CHRG PULLED LOW * ACPR PULLED LOW TEMP OK AND BATTERY > 2.8V TEMP NOT OK NTC FAULT * BATTERY CHARGING SUSPENDED * CHRG PULLED LOW BATTERY < 2.8V BATTERY < 2.8V TEMP NOT OK TEMP OK AND BATTERY > 2.8V NTC FAULT * BATTERY CHARGING SUSPENDED * CHRG PULLED LOW BATTERY > 2.8V TEMP OK AND BATTERY < 2.8V TEMP NOT OK VIN CHARGING LOW BATTERY TEMP NOT OK TEMP OK AND BATTERY < 2.8V VOUT CHARGING LOW BATTERY * BATTERY CHARGING ON * CHARGE CURRENT C/10 * CHRG PULLED LOW * BATTERY POWER TO VOUT IS OFF WALL ADAPTER PRESENT * CURRENT LIMIT FROM IN TO OUT DISABLED * BATTERY CHARGING ON * CHARGE CURRENT C/10 * CHRG PULLED LOW * ACPR PULLED LOW
4066 SD
BATTERY POWERS VOUT
VOUT > VBAT
* CHARGING SUSPENDED * CHRG HIGH-Z
VOUT < VBAT
BATTERY POWERS VOUT
VOUT > VBAT
* CHARGING SUSPENDED * CHRG PULLED LOW
VOUT < VBAT
BATTERY > 2.8V
BAD BATTERY * CHRG IS HI-Z * BATTERY POWER TO VOUT--DISABLED
1/4 TIMEOUT AND BATTERY < 2.8V
1/4 TIMEOUT AND BATTERY < 2.8V
BAD BATTERY * CHRG IS HI-Z * BATTERY POWER TO VOUT--DISABLED
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LTC4066/LTC4066-1 APPLICATIONS INFORMATION
USB Current Limit and Charge Current Control The current limit and charger control circuits of the LTC4066/LTC4066-1 are designed to limit input current as well as control battery charge current as a function of IOUT . The programmed input current limit, ICL, is defined as: 1000 1000 V ICL = * VCLPROG = RCLPROG RCLPROG The programmed battery charge current, ICHG, is defined as: 50, 000 50, 000 V ICHG = * VPROG = RPROG RPROG Input current, IIN, is equal to the sum of the BAT pin output current and the OUT pin output current: IIN = IOUT + IBAT The current limiting circuitry in the LTC4066/LTC4066-1 can and should be configured to limit current to 500mA for USB applications (selectable using the HPWR pin and programmed using the CLPROG pin). The LTC4066/LTC4066-1 reduce battery charge current such that the sum of the battery charge current and the load current does not exceed the programmed input current limit (one-fifth of the programmed input current limit when HPWR is low, see Figure 2). The battery charge current goes to zero when load current exceeds the programmed input current limit (one-fifth of the limit when HPWR is low). If the load current is greater than the current limit, the output voltage will drop to just under the battery voltage where the ideal diode circuit will take over and the excess load current will be drawn from the battery. Programming Current Limit The formula for input current limit is: 1000 1000 V ICL = * VCLPROG = RCLPROG RCLPROG where VCLPROG is the CLPROG pin voltage and RCLPROG is the total resistance from the CLPROG pin to ground. For example, if typical 500mA current limit is required, calculate: RCLPROG =
600 500 400 CURRENT (mA) CURRENT (mA) ILOAD 300 200 100 0 -100 IBAT CHARGING IIN 120 100 80 60 40 20 0 -20 IBAT CHARGING CURRENT (mA) ILOAD IIN
1V * 1000 = 2k 500mA
600 500 IIN 400 ILOAD 300 200 100 0 -100 IBAT CHARGING IBAT = ICL - IOUT IBAT = ICHG
0
100
200
300 400 ILOAD (mA)
500
600 IBAT (IDEAL DIODE)
4066 F02a
0
20
40
60 80 ILOAD (mA)
100
120 IBAT (IDEAL DIODE)
4066 F02a
0
100
200
300 400 ILOAD (mA)
500
600 IBAT (IDEAL DIODE)
4055 F02c
(2a) High Power Mode/Full Charge RPROG = 100k and RCLPROG = 2k
(2b) Low Power Mode/Full Charge RPROG = 100k and RCLPROG = 2k
(2c) High Power Mode with ICL = 500mA and ICHG = 250mA RPROG = 200k and RCLPROG = 2k
Figure 2. Input and Battery Currents as a Function of Load Current
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LTC4066/LTC4066-1 APPLICATIONS INFORMATION
In USB applications, the minimum value for RCLPROG should be 2.1k. This will prevent the application current from exceeding 500mA due to LTC4066/LTC4066-1 tolerances and quiescent currents. A 2.1k CLPROG resistor will give a typical current limit of 476mA in high power mode (HPWR = 1) or 95mA in low power mode (HPWR = 0). VCLPROG will typically servo to 1V; however, if IOUT + IBAT < ICL then VCLPROG will track the input current according to the following equation: IIN = VCLPROG * 1000 RCLPROG ideal diode circuit (along with the recommended 4.7F capacitor on the OUT pin) allows the LTC4066/LTC4066-1 to handle large transient loads and wall adapter or USB VBUS connect/disconnect scenarios without the need for large bulk capacitors. The ideal diode responds within a few microseconds and prevents the OUT pin voltage from dipping below the BAT pin voltage by more than 50mV. Forward regulation for the ideal diode from BAT to OUT has three operational ranges, depending on the magnitude of the diode load current. For small load currents, the LTC4066/LTC4066-1 will provide a constant voltage drop; this operating mode is referred to as "constant VON" regulation. As the current exceeds IFWD the voltage drop will increase linearly with the current with a slope of 1/RDIO(ON); this operating mode is referred to as "constant RON" regulation. As the current increases further, exceeding IMAX, the forward voltage drop will increase rapidly; this operating mode is referred to as "constant ION" regulation. The characteristics for parameters RFWD, RON, VFWD and IFWD are specified with the aid of Figure 3.
For best stability over temperature and time, 1% metal film resistors are recommended. Ideal Diode from BAT to OUT If a battery is the only power supply available or if the load current exceeds the programmed input current limit, then the battery will automatically deliver power to the load via an ideal diode circuit between the BAT and OUT pins. The
LTC4066 IMAX
CONSTANT ION
SLOPE: 1/RDIO(ON) CURRENT (A)
CONSTANT RON
IFWD SCHOTTKY DIODE
SLOPE: 1/RFWD
CONSTANT VON
0 VFWD
4066 F03
FORWARD VOLTAGE (V)
Figure 3. LTC4066/LTC4066-1 vs Schottky Diode Forward Voltage Drop
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LTC4066/LTC4066-1 APPLICATIONS INFORMATION
Battery Charger The battery charger circuits of the LTC4066/LTC4066-1 are designed for charging single cell lithium-ion batteries. Featuring an internal P-channel power MOSFET, the charger uses a constant-current/constant-voltage charge algorithm with programmable current and a programmable timer for charge termination. Charge current can be programmed up to 1.5A. The final float voltage accuracy is 0.8% typical. No blocking diode or sense resistor is required when powering the IN pin. The CHRG open-drain status output provides information regarding the charging status of the LTC4066/LTC4066-1 at all times. An NTC input provides the option of charge qualification using battery temperature. An internal thermal limit reduces the programmed charge current if the die temperature attempts to rise above a preset value of approximately 105C. This feature protects the LTC4066/LTC4066-1 from excessive temperature, and allows the user to push the limits of the power handling capability of a given circuit board without risk of damaging the LTC4066/LTC4066-1. Another benefit of the LTC4066/LTC4066-1 thermal limit is that charge current can be set according to typical, not worst-case, ambient temperatures for a given application with the assurance that the charger will automatically reduce the current in worst-case conditions. The charge cycle begins when the voltage at the OUT pin rises above the output UVLO level and the battery voltage is below the recharge threshold. No charge current actually flows until the OUT voltage is greater than the output UVLO level and 100mV above the BAT voltage. At the beginning of the charge cycle, if the battery voltage is below 2.8V, the charger goes into trickle charge mode to bring the cell voltage up to a safe level for charging. The charger goes into the fast charge constant-current mode once the voltage on the BAT pin rises above 2.8V. In constantcurrent mode, the charge current is set by RPROG. When the battery approaches the final float voltage, the charge current begins to decrease as the LTC4066/LTC4066-1 switches to constant-voltage mode. When the charge current drops below a level programmed by the ISTAT pin while in constant-voltage mode the CHRG pin assumes a high impedance state. An external capacitor on the TIMER pin sets the total minimum charge time. When this time elapses the charge cycle terminates and the CHRG pin assumes a high impedance state, if it has not already done so. While charging in constant-current mode, if the charge current is decreased by thermal regulation or in order to maintain the programmed input current limit the charge time is automatically increased. In other words, the charge time is extended inversely proportional to charge current delivered to the battery. For Li-Ion and similar batteries that require accurate final float potential, the internal bandgap reference, voltage amplifier and the resistor divider provide regulation with 0.8% accuracy. Trickle Charge and Defective Battery Detection At the beginning of a charge cycle, if the battery voltage is low (below 2.8V) the charger goes into trickle charge reducing the charge current to 10% of the full-scale current. If the low-battery voltage persists for one quarter of the total charge time, the battery is assumed to be defective, the charge cycle is terminated and the CHRG pin output assumes a high impedance state. If for any reason the battery voltage rises above ~2.8V, the charge cycle will be restarted. To restart the charge cycle (i.e., when the dead battery is replaced with a discharged battery), simply remove the input voltage and reapply it, cycle the TIMER pin to 0V or cycle the SHDN pin to 0V.
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LTC4066/LTC4066-1 APPLICATIONS INFORMATION
Programming Charge Current The formula for the battery charge current is: ICHG = (IPROG ) * 50, 000 = VPROG * 50, 000 RPROG where VISTAT is the ISTAT pin voltage and RISTAT is the total resistance from the ISTAT pin to ground. These pins enable a true gas gauge function to be performed on the battery with an external ADC and integrator. See Gas Gauge for more information. The Charge Timer The programmable charge timer is used to terminate the charge cycle. The timer duration is programmed by an external capacitor at the TIMER pin. The charge time is typically: t TIMER(Hours) = CTIMER * RPROG * 3Hours 0.1F * 100k
where VPROG is the PROG pin voltage and RPROG is the total resistance from the PROG pin to ground. Keep in mind that when the LTC4066/LTC4066-1 are powered from the IN pin, the programmed input current limit takes precedence over the charge current. In such a scenario, the charge current cannot exceed the programmed input current limit. For example, if typical 500mA charge current is required, calculate: 1V RPROG = * 50, 000 = 100k 500mA For best stability over temperature and time, 1% metal film resistors are recommended. Under trickle charge conditions, this current is reduced to 10% of the fullscale value. Monitoring Charge Current The ISTAT and POL pins provide a means for monitoring the BAT pin current. The ISTAT pin sources a current equal to one-thousandth of the absolute value of the current flowing in the BAT pin. The POL pin indicates the polarity of the BAT pin current. When current is flowing from OUT to BAT (i.e., charging), the POL pin pulls to ground. When current is flowing from BAT to OUT (ideal diode), the POL pin assumes a high impedance. If a resistor, RISTAT , is placed from the ISTAT pin to ground, then the formula for BAT current is: IBAT = VISTAT * 1000 RISTAT
The timer starts when an input voltage greater than the undervoltage lockout threshold level is applied or when leaving shutdown and the voltage on the battery is less than the recharge threshold. At power-up or exiting shutdown with the battery voltage less than the recharge threshold, the charge time is a full cycle. If the battery is greater than the recharge threshold, the timer will not start and charging is prevented. If after power-up the battery voltage drops below the recharge threshold, or if after a charge cycle the battery voltage is still below the recharge threshold, the charge time is set to one-half of a full cycle. The LTC4066/LTC4066-1 have a feature that extends charge time automatically. Charge time is extended if the charge current in constant-current mode is reduced due to load current or thermal regulation. This change in charge time is inversely proportional to the change in charge current. As the LTC4066/LTC4066-1 approach constant-voltage mode the charge current begins to drop. This change in charge current is due to normal charging operation and does not affect the timer duration.
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LTC4066/LTC4066-1 APPLICATIONS INFORMATION
Consider, for example, a USB charge condition where . RCLPROG = 2k, RPROG = 100k and CTIMER = 0.1F This corresponds to a three hour charge cycle. However, if the HPWR input is set to a logic low, then the input current limit will be reduced from 500mA to 100mA. With no additional system load, this means the charge current will be reduced to 100mA. Therefore, the termination timer will automatically slow down by a factor of five until the charger reaches constant voltage mode (i.e., VBAT = 4.2V, 4.1V for LTC4066-1) or HPWR is returned to a logic high. The charge cycle is automatically lengthened to account for the reduced charge current. The exact time of the charge cycle will depend on how long the charger remains in constant current mode and/or how long the HPWR pin remains a logic low. Once a time-out occurs and the voltage on the battery is greater than the recharge threshold, the charge current stops, and the CHRG output assumes a high impedance state if it has not already done so. Connecting the TIMER pin to ground disables the battery charger. CHRG Status Output Pin When the charge cycle starts, the CHRG pin is pulled to ground by an internal N-channel MOSFET capable of driving an LED. When the charge current drops below a programmable threshold while in constant-voltage mode, the pin assumes a high impedance state (but charge current continues to flow until the charge time elapses). If this state is not reached before the end of the programmable charge time, the pin will assume a high impedance state when a time-out occurs. The current level at which the CHRG pin changes state is programmed by the ISTAT pin. As described in Monitoring Charge Current and Gas Gauge, the ISTAT pin sources a current proportional to the BAT pin current. The LTC4066/ LTC4066-1 monitor the voltage on the ISTAT pin and turns off the CHRG N-channel pull-down when VISTAT drops below 100mV while in constant-voltage mode. The CHRG current detection threshold can be calculated by the following equation: IDETECT = 0.1V 100 V * 1000 = RISTAT RISTAT
For example, to program the CHRG pin to change state at a battery charge current of 100mA, choose: RISTAT = 100 V = 1k 100mA
Note: The end-of-charge (EOC) comparator that monitors the ISTAT pin voltage for 100mV latches its decision. Therefore, the first time VISTAT drops below 100mV (i.e., IBAT drops below 100V/RISTAT) while in constant voltage mode will toggle CHRG to a high impedance state. If, for some reason, the charge current rises back above the threshold, the CHRG pin will not resume the strong pulldown state. The EOC latch can be reset by toggling the SHDN pin or toggling the input power to the part. The EOC latch will also be reset if the BAT pin voltage falls below the recharge threshold.
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LTC4066/LTC4066-1 APPLICATIONS INFORMATION
NTC Thermistor The battery temperature is measured by placing a negative temperature coefficient (NTC) thermistor close to the battery pack. The NTC circuitry is shown in Figure 4. To use this feature, connect the NTC thermistor (RNTC) between the NTC pin and ground and a resistor (RNOM) from the NTC pin to VNTC. RNOM should be a 1% resistor with a value equal to the value of the chosen NTC thermistor at 25C (this value is 10k for a Vishay NTHS0603N02N1002J thermistor). The LTC4066/LTC4066-1 go into hold mode when the resistance (RHOT) of the NTC thermistor drops to 0.41 times the value of RNOM or approximately 4.1k, which should be at 50C. The hold mode freezes the timer and stops the charge cycle until the thermistor indicates a return to a valid temperature. As the temperature drops, the resistance of the NTC thermistor rises. The LTC4066/ LTC4066-1 are designed to go into hold mode when the value of the NTC thermistor increases to 2.82 times the value of RNOM. This resistance is RCOLD. For a Vishay NTHS0603N02N1002J thermistor, this value is 28.2k which corresponds to approximately 0C. The hot and cold comparators each have approximately 3C of hysteresis to prevent oscillation about the trip point. Grounding the NTC pin can disable the NTC function. Thermistors The LTC4066/LTC4066-1 NTC trip points were designed to work with thermistors whose resistance-temperature characteristics follow Vishay Dale's "R-T Curve 2". The Vishay NTHS0603N02N1002J is an example of such a thermistor. However, Vishay Dale has many thermistor products that follow the "R-T Curve 2" characteristic in a variety of sizes. Furthermore, any thermistor whose ratio of RCOLD to RHOT is about 7.0 will also work (Vishay Dale R-T Curve 2 shows a ratio of RCOLD to RHOT of 2.815/0.4086 = 6.89).
VNTC 15 RNOM 10k NTC 14 0.74 * VNTC
LTC4066
VNTC 15
LTC4066
-
TOO_COLD
RNOM 121k NTC 14
0.74 * VNTC
-
TOO_COLD
+
+
RNTC 10k 0.29 * VNTC
-
TOO_HOT
R1 13.3k 0.29 * VNTC RNTC 100k
-
TOO_HOT
+
+
+
NTC_ENABLE 0.1V
+
NTC_ENABLE 0.1V
-
4066 F04a
-
4055 F03b
(4a) Figure 4. NTC Circuits
(4b)
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20
LTC4066/LTC4066-1 APPLICATIONS INFORMATION
Power conscious designs may want to use thermistors whose room temperature value is greater than 10k. Vishay Dale has a number of values of thermistor from 10k to 100k that follow the "R-T Curve 2." Using these directly in the manor spelled out previously in the NTC Thermistor section will give temperature trip points of approximately 3C and 47C, a delta of 44C. This delta in temperature can be moved in either direction by changing the value of RNOM with respect to RNTC. Increasing RNOM will move both trip points to lower temperatures. Likewise a decrease in RNOM with respect to RNTC will move the trip points to higher temperatures. To calculate RNOM for a shift to lower temperature for example, use the following equation:
RNOM = RCOLD * RNTC at 25C 2.815
The nearest 1% value for RNOM is 115k. This is the value used to bias the NTC thermistor to get cold and hot trip points of approximately 0C and 44C respectively. To extend the delta between the cold and hot trip points, a resistor (R1) can be added in series with RNTC (see Figure 3b). The values of the resistors are calculated as follows:
RCOLD - RHOT 2.815 - 0.4086 0.4086 R1 = * (RCOLD - RHOT ) - RHOT 2.815 - 0.4086 RNOM =
where RCOLD is the resistance ratio of RNTC at the desired cold temperature trip point. If you want to shift the trip points to higher temperatures, use the following equation:
RNOM = RHOT * RNTC at 25C 0.4086
where RNOM is the value of the bias resistor, RHOT and RCOLD are the values of RNTC at the desired temperature trip points. Continuing the example from before with a desired hot trip point of 50C:
RNOM = RCOLD - RHOT 100k * (3.266 - 0.3602) = 2.815 - 0.4086 2.815 - 0.4086 = 120.8k, 121k nearest 1%
where RHOT is the resistance ratio of RNTC at the desired hot temperature trip point. Here is an example using a 100k R-T Curve 1 Thermistor from Vishay Dale. The difference between the trip points is 44C, from before, and we want the cold trip point to be 0C, which would put the hot trip point at 44C. The RNOM needed is calculated as follows:
RNOM = RCOLD * RNTC at 25C 2.815 3.266 = * 100k = 116k 2.815
0.4086 R1 = 100k * * (3.266 - 0.3602) - 0.3602 2.815 - 0.4086 = 13.3k, 13.3k is nearest 1%
The final solution is as shown if Figure 3b where RNOM = 121k, R1 = 13.3k and RNTC = 100k at 25C. Gas Gauge The extremely low impedance of the ideal diode between BAT and OUT (typically 50m) allows users to connect all of their loads to the OUT pin. Such a configuration puts the LTC4066/LTC4066-1 in a unique position whereby it can monitor all of the current that flows into and out of the battery. Two output pins, ISTAT and POL, are provided to enable users to monitor and integrate the battery current for a true gas gauge function.
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21
LTC4066/LTC4066-1 APPLICATIONS INFORMATION
Any time a battery is connected to the BAT pin and the SHDN pin is low, the BAT pin current can be monitored with the following equation: IBAT = VISTAT * 1000 RISTAT voltage should not exceed approximately VBAT - 0.5V (for the typical minimum operating voltage for the ideal diode this value would be 2.8V - 0.5V = 2.3V). Typically, it is this second case that is the limiting situation since VBAT is typically lower than VOUT (while charging) and transient ideal diode loads tend to be greater than typical charge currents (causing a higher voltage on the ISTAT pin). Therefore, choosing a value of RISTAT based on the CHRG detection current may limit the maximum ideal diode load current that can be sensed accurately. Consider an example: a) Desired charge current = 850mA b) Desired CHRG detection current = 100mA c) Maximum transient ideal diode current = 1.5A Calculate: a) RPROG = (1V/850mA) * 50,000 = 59k b) RISTAT = 100V/100mA = 1k c) VISTAT(MAX) = 1.5A/1000 * 1k = 1.5V In this example, there is no common mode problem because the maximum ISTAT voltage (1.5V) is well below the 2.3V minimum. However, if, instead of 100mA, the desired CHRG detection current was lowered to 40mA, then the desired RISTAT resistor would increase to 2.5k (100V/40mA) and the maximum ISTAT voltage would increase to 3.75V (assuming no change in the 1.5A maximum ideal diode current). Therefore, ideal diode currents greater than 920mA (2.3V/2.5k * 1000) might not be reported accurately. To calculate the maximum ideal diode current that will be reported accurately: IDMON(MAX) = VBAT - 0.5V RISTAT
where |IBAT| is the absolute value of the BAT pin current, VISTAT is the voltage on the ISTAT pin and RISTAT is the total resistance from the ISTAT pin to ground. The POL pin has two states: high impedance and strong pull-down. High impedance indicates that current is flowing from BAT to OUT (ideal diode function) and strong pull-down indicates that current is flowing from OUT to BAT (charging). If an external ADC is used to convert the ISTAT voltage, then the POL pin can be thought of as a sign bit. When the ideal diode function is operating, the ISTAT pin cannot monitor ideal diode load currents less than about 1mA. For any ideal diode load current less than 1mA, the ISTAT pin will source a constant current of approximately 1A. However, when the battery charger function is operating, the ISTAT pin will continue to source one-thousandth of the battery charge current even if the charge current drops to less than 1mA. When choosing the value of RISTAT, two details must be considered. For the battery charger function, the value of RISTAT programs the charge current below which the CHRG pin transitions to its high impedance state (see CHRG Status Output Pin). Furthermore, the available common mode range on the ISTAT pin needed to maintain an accurate ratio between IBAT and IISTAT is limited. When charging, the ISTAT pin voltage should not exceed approximately VOUT - 0.5V. When the ideal diode is functioning, the ISTAT pin
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LTC4066/LTC4066-1 APPLICATIONS INFORMATION
Current Limit Undervoltage Lockout An internal undervoltage lockout circuit monitors the input voltage and disables the input current limit circuits until VIN rises above the undervoltage lockout threshold. The current limit UVLO circuit has a built-in hysteresis of 125mV. Furthermore, to protect against reverse current in the power MOSFET, the current limit UVLO circuit disables the current limit (i.e., forces the input power path to a high impedance state) if VOUT exceeds VIN. If the current limit UVLO comparator is tripped, the current limit circuits will not come out of shutdown until VOUT falls 50mV below the VIN voltage. Charger Undervoltage Lockout An internal undervoltage lockout circuit monitors the VOUT voltage and disables the battery charger circuits until VOUT rises above the undervoltage lockout threshold. The battery charger UVLO circuit has a built-in hysteresis of 125mV. Furthermore, to protect against reverse current in the power MOSFET, the charger UVLO circuit keeps the charger shutdown if VBAT exceeds VOUT. If the charger UVLO comparator is tripped, the charger circuits will not come out of shutdown until VOUT exceeds VBAT by 50mV. Shutdown The LTC4066/LTC4066-1 can be shutdown by forcing the SHDN pin greater than 1.2V. In shutdown, the currents drawn from IN, OUT and BAT are decreased to less than 2.5A and the internal battery charge timer and end-ofcharge comparator output are reset. All power paths are put in a high impedance state. Suspend The LTC4066/LTC4066-1 can be put in suspend mode by forcing the SUSP pin greater than 1.2V. In suspend mode the ideal diode function from BAT to OUT is kept alive. If power is applied to the OUT pin externally (i.e., a wall adapter is present) then charging will be unaffected. Current drawn from the IN pin is reduced to 50A. Suspend mode is intended to comply with the USB Power Specification mode of the same name. Selecting WALL Input Resistors The WALL input pin identifies the presence of a wall adapter. This information is used to disconnect the input pin, IN, from the OUT pin in order to prevent back conduction to whatever may be connected to the input. It also forces the ACPR pin low when the voltage at the WALL pin exceeds the input threshold. The WALL pin has a 1.225V rising threshold and approximately 30mV of hysteresis. The wall adapter detection threshold is set by the following equation: R1 VTH( Adapter ) = VWALL * 1 + R2 R1 VHYST ( Adapter ) = VWALL(HYST) * 1 + R2 where VTH(Adapter) is the wall adapter detection threshold, VWALL is the WALL pin rising threshold (typically 1.225V), R1 is the resistor from the wall adapter input to WALL and R2 is the resistor from WALL to GND.
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23
LTC4066/LTC4066-1 APPLICATIONS INFORMATION
Consider an example where the VTH(Adapter) is to be set somewhere around 4.5V. Resistance on the WALL pin should be kept relatively low (~10k) in order to prevent false tripping of the wall comparator due to leakages associated with the switching element used to connect the adapter to OUT. Pick R2 to be 10k and solve for R1: V ( Adapter ) R1 = R2 * TH - 1 VWALL 4.5V R1 = 10k * - 1 = 10k * 2.67 = 26.7k 1.225V The nearest 1% resistor is 26.7k. Therefore, R1 = 26.7k and the rising trip point should be 4.50V. 26.7k VHYST ( Adapter ) 30mV * 1 + 110.1mV 10k The hysteresis is going to be approximately 110mV for this example. Power Dissipation The conditions that cause the LTC4066/LTC4066-1 to reduce charge current due to the thermal protection feedback can be approximated by considering the power dissipated in the part. For high charge currents and a wall adapter applied to VOUT , the LTC4066/LTC4066-1 power dissipation is approximately: PD = (VOUT - VBAT) * IBAT where PD is the power dissipated, VOUT is the supply voltage, VBAT is the battery voltage and IBAT is the battery charge current. It is not necessary to perform any worstcase power dissipation scenarios because the LTC4066/ LTC4066-1 will automatically reduce the charge current to maintain the die temperature at approximately 105C. However, the approximate ambient temperature at which the thermal feedback begins to protect the IC is: TA = 105C - PD * JA TA = 105C - (VOUT - VBAT) * IBAT * JA Example: Consider an LTC4066/LTC4066-1 operating from a wall adapter with 5V at VOUT providing 0.8A to a 3V Li-Ion battery. The ambient temperature above which the LTC4066/LTC4066-1 will begin to reduce the 0.8A charge current, is approximately: TA = 105C - (5V - 3V) * 0.8A * 37C/W TA = 105C - 1.6W * 37C/W = 105C - 59C = 46C The LTC4066/LTC4066-1 can be used above 46C, but the charge current will be reduced below 0.8A. The charge current at a given ambient temperature can be approximated by: IBAT = 105C - TA ( VOUT - VBAT ) * JA
Consider the above example with an ambient temperature of 55C. The charge current will be reduced to approximately: IBAT = 105C - 55C 50C = = 0.675A (5V - 3V) * 37C/W 74C/A
Board Layout Considerations In order to be able to deliver maximum charge current under all conditions, it is critical that the Exposed Pad on the backside of the LTC4066/LTC4066-1 package is soldered to the board. Correctly soldered to a 2500mm2 double-sided 1oz. copper board, the LTC4066/LTC4066-1 has a thermal resistance of approximately 37C/W. Failure
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LTC4066/LTC4066-1 APPLICATIONS INFORMATION
to make thermal contact between the Exposed Pad on the backside of the package and the copper board will result in thermal resistances far greater than 37C/W. As an example, a correctly soldered LTC4066/LTC4066-1 can deliver over 1A to a battery from a 5V supply at room temperature. Without a backside thermal connection, this number could drop to less than 500mA. Furthermore, Pins 6 and 7 are "true No Connect" pins. Therefore, they can be used to improve the amount of metal used to connect to Pin 5 or Pin 8. VIN and Wall Adapter Bypass Capacitor Many types of capacitors can be used for input bypassing. However, caution must be exercised when using multilayer ceramic capacitors. Because of the self resonant and high Q characteristics of some types of ceramic capacitors, high voltage transients can be generated under some start-up conditions, such as connecting the charger input to a hot power source. For more information, refer to Application Note 88. Stability The constant-voltage mode feedback loop is stable without any compensation when a battery is connected. However, a 4.7F capacitor with a 1 series resistor to GND is recommended at the BAT pin to keep ripple voltage low when the battery is disconnected.
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25
LTC4066/LTC4066-1 PACKAGE DESCRIPTION
UF Package 24-Lead Plastic QFN (4mm x 4mm)
(Reference LTC DWG # 05-08-1697)
0.70 0.05
4.50
0.05 3.10
2.45 0.05 0.05 (4 SIDES)
PACKAGE OUTLINE
0.25 0.05 0.50 BSC RECOMMENDED SOLDER PAD PITCH AND DIMENSIONS BOTTOM VIEW--EXPOSED PAD 0.75 0.05 R = 0.115 TYP PIN 1 NOTCH R = 0.20 TYP OR 0.35 45 CHAMFER
4.00 0.10 (4 SIDES) PIN 1 TOP MARK (NOTE 6)
23 24 0.40 1 2 0.10
2.45 0.10 (4-SIDES)
(UF24) QFN 0105
0.200 REF 0.00 - 0.05 NOTE: 1. DRAWING PROPOSED TO BE MADE A JEDEC PACKAGE OUTLINE MO-220 VARIATION (WGGD-X)--TO BE APPROVED 2. DRAWING NOT TO SCALE 3. ALL DIMENSIONS ARE IN MILLIMETERS 4. DIMENSIONS OF EXPOSED PAD ON BOTTOM OF PACKAGE DO NOT INCLUDE MOLD FLASH. MOLD FLASH, IF PRESENT, SHALL NOT EXCEED 0.15mm ON ANY SIDE, IF PRESENT 5. EXPOSED PAD SHALL BE SOLDER PLATED 6. SHADED AREA IS ONLY A REFERENCE FOR PIN 1 LOCATION ON THE TOP AND BOTTOM OF PACKAGE
0.25
0.05
0.50 BSC
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26
LTC4066/LTC4066-1 PACKAGE DESCRIPTION
PF Package 24-Lead Plastic UTQFN (4mm x 4mm)
(Reference LTC DWG # 05-08-1748 Rev O)
0.70 0.05
2.45 4.50 0.05 3.10 2.50 REF 0.05
0.05
2.45
0.05
PACKAGE OUTLINE
0.25 0.05 0.50 BSC RECOMMENDED SOLDER PAD PITCH AND DIMENSIONS APPLY SOLDER MASK TO AREAS THAT ARE NOT SOLDERED 0.55 4.00 PIN 1 TOP MARK (NOTE 6) 2.45 4.00 0.10 2.50 REF 2.45 0.10 0.10 0.10 0.05 R = 0.05 TYP
BOTTOM VIEW--EXPOSED PAD R = 0.115 TYP
PIN 1 NOTCH R = 0.20 TYP OR 0.35 45 CHAMFER 0.40 1 2 0.10
23 24
(PF24) UTQFN 0107
0.125 REF 0.00 - 0.05 NOTE: 1. DRAWING IS NOT A JEDEC PACKAGE OUTLINE 2. DRAWING NOT TO SCALE 3. ALL DIMENSIONS ARE IN MILLIMETERS 4. DIMENSIONS OF EXPOSED PAD ON BOTTOM OF PACKAGE DO NOT INCLUDE MOLD FLASH. MOLD FLASH, IF PRESENT, SHALL NOT EXCEED 0.15mm ON ANY SIDE, IF PRESENT 5. EXPOSED PAD SHALL BE SOLDER PLATED 6. SHADED AREA IS ONLY A REFERENCE FOR PIN 1 LOCATION ON THE TOP AND BOTTOM OF PACKAGE
0.25
0.05
0.50 BSC
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Information furnished by Linear Technology Corporation is believed to be accurate and reliable. However, no responsibility is assumed for its use. Linear Technology Corporation makes no representation that the interconnection of its circuits as described herein will not infringe on existing patent rights.
27
LTC4066/LTC4066-1 TYPICAL APPLICATION
USB Power Control Application with Wall Adapter Input
5V WALL ADAPTER INPUT TO LDOs REGs, ETC
4.7F 1*
10k
510
510
4.7F
5V (NOM) FROM USB CABLE VBUS
IN 4.7F 1* R1 26.7k CHRG ACPR WALL R2 10k SHUTDOWN SUSPEND USB POWER 500mA/100mA SELECT INPUT CURRENT LIMIT DISABLE *SERIES 1 RESISTOR ONLY NEEDED FOR INDUCTIVE INPUT SUPPLIES SHDN SUSP HPWR CLDIS PROG CLPROG
OUT BAT VNTC NTC LTC4066 RNTC 100k POL ISTAT TIMER GND 0.15F RISTAT 2k
4006 TA03
+
RNTCBIAS 100k
Li-Ion CELL
TO ADC FOR GAS GAUGE
RPROG 71.5k
RCLPROG 2.1k
RELATED PARTS
PART NUMBER Battery Chargers LTC1733 LTC1734 LTC1734L LTC4002 LTC4052 LTC4053 LTC4054 LTC4057 LTC4058 LTC4059 LTC4411/LTC4412 DESCRIPTION Monolithic Lithium-Ion Linear Battery Charger Lithium-Ion Linear Battery Charger in ThinSOTTM Lithium-Ion Linear Battery Charger in ThinSOT Switch Mode Lithium-Ion Battery Charger Monolithic Lithium-Ion Battery Pulse Charger USB Compatible Monolithic Li-Ion Battery Charger Standalone Linear Li-Ion Battery Charger with Integrated Pass Transistor in ThinSOT Lithium-Ion Linear Battery Charger Standalone 950mA Lithium-Ion Charger in DFN 900mA Linear Lithium-Ion Battery Charger Low Loss PowerPath Controller in ThinSOT COMMENTS Standalone Charger with Programmable Timer, Up to 1.5A Charge Current Simple ThinSOT Charger, No Blocking Diode, No Sense Resistor Needed Low Current Version of LTC1734; 50mA ICHRG 180mA Standalone, 4.7V VIN 24V, 500kHz Frequency, 3-Hour Charge Termination No Blocking Diode or External Power FET Required, 1.5A Charge Current Standalone Charger with Programmable Timer, Up to 1.25A Charge Current Thermal Regulation Prevents Overheating, C/10 Termination, C/10 Indicator, Up to 800mA Charge Current Up to 800mA Charge Current, Thermal Regulation, ThinSOT Package C/10 Charge Termination, Battery Kelvin Sensing, 7% Charge Accuracy 2mm x 2mm DFN Package, Thermal Regulation, Charge Current Monitor Output Automatic Switching Between DC Sources, Load Sharing, Replaces ORing Diodes 95% Efficiency, VIN = 2.7V to 6V, VOUT = 0.8V, IQ = 20A, ISD < 1A, ThinSOT Package 95% Efficiency, VIN = 2.5V to 5.5V, VOUT = 0.6V, IQ = 20A, ISD < 1A, ThinSOT Package 95% Efficiency, VIN = 2.5V to 5.5V, VOUT = 0.8V, IQ = 60A, ISD < 1A, MS10 Package 95% Efficiency, VIN = 2.5V to 5.5V, VOUT = 2.5V, IQ = 25A, ISD < 1A, MS Package Seamless Transition Between Power Sources: USB, Wall Adapter and Battery; 95% Efficient DC/DC Conversion Charges Single Cell Li-Ion Batteries Directly from a USB Port, Thermal Regulation, 200m Ideal Diode, 4mm x 4mm QFN16 Package
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Power Management LTC3405/LTC3405A 300mA (IOUT), 1.5MHz, Synchronous Step-Down DC/DC Converters LTC3406/LTC3406A 600mA (IOUT), 1.5MHz, Synchronous Step-Down DC/DC Converters LTC3411 1.25A (IOUT), 4MHz, Synchronous Step-Down DC/DC Converter LTC3440 600mA (IOUT), 2MHz, Synchronous Buck-Boost DC/DC Converter LTC3455 Dual DC/DC Converter with USB Power Manager and Li-Ion Battery Charger LTC4055 USB Power Controller and Battery Charger ThinSOT is a trademark of Linear Technology Corporation.
28 Linear Technology Corporation
(408) 432-1900 FAX: (408) 434-0507
LT 0108 REV C * PRINTED IN USA
1630 McCarthy Blvd., Milpitas, CA 95035-7417
www.linear.com
(c) LINEAR TECHNOLOGY CORPORATION 2005

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