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19-5296; Rev 0; 6/10
Dual-Input Linear Charger, Smart Power Selector with Advanced Battery Temperature Monitoring
General Description
The MAX8934G dual-input Li+/Li-Poly linear battery charger with Smart Power SelectorK safely charges a single Li+/Li-Poly cell in accordance with JEITA* recommendations. The MAX8934G monitors the battery temperature (TBATT) while charging, and automatically adjusts the fast-charge current and charge termination voltage as the battery temperature varies. The MAX8934G also monitors the battery temperature while the battery is discharging, and provides a warning flag (OT) to the system in the event that the battery is over temperature. Safety region 2 is supported (see Figure 6 for details). An ultra-low IQ, always-on LDO provides an additional 3.3V supply for system power. The MAX8934G operates with either separate inputs for USB and AC adapter power, or from a single input that accepts both. All power switches for charging and switching the load between battery and external power are included on-chip. No external MOSFETs are required. The MAX8934G features a Smart Power Selector to make the best use of limited USB or adapter power. Input current limit and battery charge current limit are independently set. Input power not used by the system charges the battery. Charge current limit and DC current limit can be set up to 1.5A and 2A, respectively, while USB input current can be set to 100mA or 500mA. Automatic input selection switches the system load from battery to external power. The MAX8934G provides a SYS output voltage of 4.35V. Other features include overvoltage protection (OVP), open-drain charge status and fault outputs, power-OK monitors, charge timers, and a battery thermistor monitor. Additionally, on-chip thermal limiting reduces the battery charge-rate to prevent charger overheating. The MAX8934G is available in a 28-pin, 4mm x 4mm, TQFN package.
Features
S Li+ Charger with Smart Power Selector, No External MOSFETs Needed S Monitors Battery Temperature and Adjusts Charge Current and Termination Voltage Automatically per JEITA Recommendations S OT Flags System of a Hot Battery During Discharge S Ultra-Low IQ, Always-On 3.3V LDO S Common or Separate USB and Adapter Inputs S Automatic Adapter/USB/Battery Switchover S Load Peaks in Excess of Adapter Rating are Supported by Battery S Input OVP to 16V (DC) and 9V (USB) S 40mI SYS-to-BATT Switch S Thermal Regulation Prevents Overheating S 4.35V SYS Regulation Voltage
MAX8934G
Ordering Information
PART MAX8934GETI+ **EP = Exposed pad. TEMP RANGE -40NC to +85NC PIN-PACKAGE 28 Thin QFN-EP**
+Denotes a lead(Pb)-free/RoHS-compliant package.
Typical Operating Circuit
LDO 3.3V ALWAYS-ON LINEAR REGULATOR AC ADAPTER DC Q1 CHARGE CURRENT Q3 CHARGE AND SYS LOAD SWITCH SYS LOAD CURRENT SYSTEM LOAD
Applications
PDAs, Palmtop, and Wireless Handhelds Portable Media, MP3 Players, and PNDs Digital Still Cameras and Digital Video Cameras Handheld Game Systems
*JEITA (Japan Electronics and Information Technology Industries Association) Standard, A Guide to the Safe Use of Secondary Lithium Ion Batteries on Notebook-Type Personal Computers, April 20, 2007. Smart Power Selector is a trademark of Maxim Integrated Products, Inc.
USB
USB Q2
BATT
BATTERY
GND
MAX8934G
_______________________________________________________________ Maxim Integrated Products 1
For pricing, delivery, and ordering information, please contact Maxim Direct at 1-888-629-4642, or visit Maxim's website at www.maxim-ic.com.
Dual-Input Linear Charger, Smart Power Selector with Advanced Battery Temperature Monitoring MAX8934G
ABSOLUTE MAXIMUM RATINGS
DC, PEN1 to GND .................................................-0.3V to +16V USB to GND ............................................................-0.3V to +9V VL to GND ...............................................................-0.3V to +4V LDO to GND ......... -0.3V to the lower of +4V and (VSYS + 0.3V) THMEN, THMSW to GND ..................... -0.3V to +(VLDO + 0.3V) THM to GND .......................................-0.3V to (VTHMSW + 0.3V) PSET, ISET, CT to GND............................... -0.3V to (VL + 0.3V) BATT, SYS, CEN, CHG, OT, DOK, UOK, FLT, DONE, USUS, PEN2 to GND.............-0.3V to +6V EP (Exposed Pad) to GND ...................................-0.3V to +0.3V DC Continuous Current (total in two pins) .................... 2.4ARMS SYS Continuous Current (total in two pins) ................... 2.4ARMS USB Continuous Current (total in two pins) .................. 2.0ARMS BATT Continuous Current (total in two pins)................. 2.4ARMS LDO Continuous Current ............................................. 50mARMS LDO Short-Circuit Duration ......................................... Continuous Continuous Power Dissipation (TA = +70NC) Single-Layer Board (derate 20.8mW/NC above +70NC) ......................1666.7mW Multilayer Board (derate 28.6mW/NC above +70NC) ......................2285.7mW Operating Temperature Range .......................... -40NC to +85NC Junction Temperature ...................................... -40NC to +125NC Storage Temperature ....................................... -65NC to +150NC Lead Temperature (soldering, 10s) ................................+300NC Soldering Temperature (reflow) ......................................+260NC
Stresses beyond those listed under "Absolute Maximum Ratings" may cause permanent damage to the device. These are stress ratings only, and functional operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to absolute maximum rating conditions for extended periods may affect device reliability.
ELECTRICAL CHARACTERISTICS
(VDC = VPEN1 = VPEN2 = 5V, CEN = USUS = THMEN = GND, VBATT = 4V, VTHM = 1.65V, USB, THMSW, CHG, DONE, OT, DOK, UOK, FLT are unconnected, CCT = 0.068FF, TA = -40NC to +85NC, unless otherwise noted. Typical values are at TA = +25NC.) (Note 1) PARAMETER DC-to-SYS PREREGULATOR DC Operating Voltage Range DC Withstand Voltage DC Undervoltage Threshold DC Overvoltage Threshold DC Operating Supply Current DC Suspend Current DC-to-SYS On-Resistance DC to BATT Dropout Voltage VBATT = VSYS = 0V When V DOK goes low, VDC rising, 500mV hysteresis When V DOK goes high, VDC rising, 360mV hysteresis ISYS = IBATT = 0mA, V CEN = 0V ISYS = IBATT = 0mA, V CEN = 5V VDC = V CEN = VUSUS = 5V, VPEN1 = 0V ISYS = 400mA, V CEN = 5V When SYS regulation and charging stops, VDC falling, 150mV hysteresis RPSET = 1.5kI RPSET = 3kI DC Current Limit VDC = 5V, VSYS = 4V, TA = +25NC RPSET = 6.3kI VPEN1 = 0V, VPEN2 = 5V (500mA USB mode) VPEN1 = VPEN2 = 0V (100mA USB mode) PSET Resistance Range SYS Regulation Voltage Input Current Soft-Start Time Thermal-Limit Temperature Thermal-Limit Gain VL Voltage 2 VDC = 6V, ISYS = 1mA to 1.75A, V CEN = 5V Connecting DC with USB not present Connecting DC with USB present Die temperature at when the charging current and input current limits are reduced ISYS reduction with die temperature (above +100NC) IVL = 0 to 5mA, USB = unconnected 3 10 1800 900 450 450 80 1.5 4.29 4.35 1.5 50 100 5 3.3 3.6 3.95 6.8 4.0 6.9 1 0.8 195 0.2 50 2000 1000 475 475 95 4.1 6.6 14 4.05 7.0 2 1.5 340 0.35 90 2200 1100 500 500 100 6.3 4.4 kI V ms Fs NC %/C V mA V V V V mA FA I mV CONDITIONS MIN TYP MAX UNITS
______________________________________________________________________________________
Dual-Input Linear Charger, Smart Power Selector with Advanced Battery Temperature Monitoring
ELECTRICAL CHARACTERISTICS (continued)
(VDC = VPEN1 = VPEN2 = 5V, CEN = USUS = THMEN = GND, VBATT = 4V, VTHM = 1.65V, USB, THMSW, CHG, DONE, OT, DOK, UOK, FLT are unconnected, CCT = 0.068FF, TA = -40NC to +85NC, unless otherwise noted. Typical values are at TA = +25NC.) (Note 1) PARAMETER USB-TO-SYS PREREGULATOR USB Operating Voltage Range USB Withstand Voltage USB Undervoltage Threshold USB Overvoltage Threshold USB Operating Supply Current USB Suspend Current USB to SYS On-Resistance USB-to-BATT Dropout Voltage USB Current Limit (See Table 2) SYS Regulation Voltage Input Limiter Soft-Start Time Thermal-Limit Temperature Thermal-Limit Gain VL Voltage LDO LINEAR REGULATOR DC unconnected, VUSB = 5V, ILDO = 0mA LDO Output Voltage LDO Load Regulation BATTERY CHARGER BATT-to-SYS On-Resistance BATT-to-SYS Reverse Regulation Voltage VDC = 0V, VBATT = 4.2V, ISYS = 1A VPEN1 = VPEN2 = 0V, ISYS = 200mA TA = +25NC, VTHM_T2 < VTHM < VTHM_T3 TA = 0NC to +85NC, VTHM_T2 < VTHM < VTHM_T3 BATT Regulation Voltage--Safety IBATT = 0mA Region 2 TA = +25NC, VTHM_T1 < VTHM < VTHM_T2 or VTHM_T3 < VTHM < VTHM_T4 TA = 0NC to +85NC, VTHM_T1 < VTHM < VTHM_T2 or VTHM_T3 < VTHM < VTHM_T4 50 4.175 4.158 0.04 75 4.2 4.2 0.08 105 4.225 4.242 V I mV VDC = 5V, USB unconnected, ILDO = 0mA DC and USB unconnected, VBATT = 4V, ILDO = 0mA ILDO = 0 to 30mA 3.234 3.234 3.234 3.3 3.3 3.3 0.003 3.366 3.366 3.366 %/mA V VBATT = VSYS = 0V When V UOK goes low, VUSB rising, 500mV hysteresis When V UOK goes high, VUSB rising, 360mV hysteresis ISYS = IBATT = 0mA, V CEN = VPEN2 = 0V ISYS = IBATT = 0mA, V CEN = 5V, VPEN2 = 0V DC = unconnected, VUSB = V CEN = VUSUS = 5V DC unconnected, VUSB = V CEN = 5V, ISYS = 400mA When SYS regulation and charging stops, VUSB falling, 150mV hysteresis DC unconnected, VUSB = 5V, TA = +25NC VPEN1 = 0V, VPEN2 = 5V VPEN1 = VPEN2 = 0V 10 450 80 4.29 3.95 6.8 4.0 6.9 1 0.9 190 0.22 50 475 95 4.35 50 100 5 3 3.3 3.6 4.1 6.6 8 4.05 7.0 2 1.5 340 0.33 90 500 100 4.4 V V V V mA FA I mV mA V Fs NC %/NC V CONDITIONS MIN TYP MAX UNITS
MAX8934G
DC unconnected, VUSB = 6V, VPEN2 = 5V, ISYS = 1mA to 400mA, VCEN = 5V Input current ramp time Die temperature at when the charging current and input current limits are reduced ISYS reduction with die temperature (above +100NC) DC unconnected, VUSB = 5V, IVL = 0 to 5mA
4.05
4.075
4.1
4.034
4.075
4.1
_______________________________________________________________________________________
3
Dual-Input Linear Charger, Smart Power Selector with Advanced Battery Temperature Monitoring MAX8934G
ELECTRICAL CHARACTERISTICS (continued)
(VDC = VPEN1 = VPEN2 = 5V, CEN = USUS = THMEN = GND, VBATT = 4V, VTHM = 1.65V, USB, THMSW, CHG, DONE, OT, DOK, UOK, FLT are unconnected, CCT = 0.068FF, TA = -40NC to +85NC, unless otherwise noted. Typical values are at TA = +25NC.) (Note 1) PARAMETER BATT Recharge Threshold-- Safety Region 2 BATT Fast-Charge Current Range Change in VBATT from DONE to fastcharge restart RISET = 10kI to 2kI RISET = 2kI RISET = 4kI VSYS = 5.5V, VTHM_T1 < VTHM < VTHM_T4 (safety region 2) RISET = 10kI RISET = 2kI, VBATT = 2.5V (prequal) RISET = 4kI, VBATT = 2.5V (prequal) RISET = 10kI, VBATT = 2.5V (prequal) ISET Output Voltage Charger Soft-Start Time BATT Prequal Threshold RISET = 4kI, IBATT = 500mA (VISET = 1.5V at full charge current) VTHM_T1 < VTHM < VTHM_T4 Charge-current ramp time VBATT rising, 180mV hysteresis No DC or USB power connected, THMEN = low, VCEN = 5V BATT Input Current VBATT = 4.2V, ILDO = 0 No DC or USB power connected, THMEN = high, V CEN = 5V DC or USB power connected, V CEN = 5V DONE Threshold as a Percentage of Fast-Charge Current Maximum Prequal Time Maximum Fast-Charge Time Maximum Top-Off Time Timer Accuracy Timer Extend Threshold Timer Suspend Threshold Percentage of fast-charge current below where the timer clock operates at half-speed Percentage of fast-charge current below where timer clock pauses -20 50 20 IBATT decreasing From CEN falling to end of prequal charge, VBATT = 2.5V From CEN falling to FLT falling 2.9 0.9 CONDITIONS VTHM_T2 < VTHM < VTHM_T3 VTHM_T1 < VTHM < VTHM_T2 or VTHM_T3 < VTHM < VTHM_T4 MIN -145 -120 0.3 1350 675 270 270 130 1500 750 300 300 150 60 1 1.5 3 5 3.1 12 1.1 V ms V TYP -104 -80 MAX -65 -40 1.5 1650 825 330 330 170 mA mV UNITS
A
BATT Charge Current Accuracy
12 0.003
25 2
FA
20 180 300 15 +20
% min min s % % %
4
______________________________________________________________________________________
Dual-Input Linear Charger, Smart Power Selector with Advanced Battery Temperature Monitoring
ELECTRICAL CHARACTERISTICS (continued)
(VDC = VPEN1 = VPEN2 = 5V, CEN = USUS = THMEN = GND, VBATT = 4V, VTHM = 1.65V, USB, THMSW, CHG, DONE, OT, DOK, UOK, FLT are unconnected, CCT = 0.068FF, TA = -40NC to +85NC, unless otherwise noted. Typical values are at TA = +25NC.) (Note 1) PARAMETER THERMISTOR MONITOR (Beta = 3964) (Note 2) THM Cold No-Charge Threshold (T1) CONDITIONS MIN -2.1 ICHG = 0A, when charging is suspended, 2NC hysteresis 76.4 8.2 THM Cold Threshold (T2) VBATT_REG, reduced, 2NC hysteresis 66.2 42.8 THM Hot Threshold (T3) VBATT_REG reduced, 2.5NC hysteresis 29.8 57 19.5 71 OT asserts low, 5NC hysteresis TA = +25NC TA = +85NC TA = +25NC TA = +85NC VLDO 0.05 1.3 0.4 50 TA = +25NC TA = +85NC TA = +25NC TA = +85NC 0.001 0.01 25 0.001 0.01 100 1 1 -0.2 12.6 -1 TYP 0 77.2 10 67 45 30 60 19.8 75 12.9 +0.001 0.01 +0.001 0.01 +1 MAX +2.4 77.9 12 67.6 47.5 30.6 63.5 20.1 80 13.1 +1 UNITS NC % of THMSW NC % of THMSW NC % of THMSW NC % of THMSW NC % of THMSW FA FA V
MAX8934G
THM Hot No-Charge Threshold (T4) THM Hot Discharge Threshold (TOT) THM Input leakage THMSW Output Leakage THMSW Output Voltage High
ICHG = 0mA, when charging is suspended, 3NC hysteresis
THM = GND or LDO THMSW = GND Sourcing 1mA
LOGIC I/O: PEN1, PEN2, CHG, FLT, DONE, DOK, UOK, USUS, THMEN) High level Logic-Input Thresholds Low level Hysteresis Logic-Input Leakage Current Logic-Low Output Voltage Logic-High Output Leakage Current VIN = 0 to 5.5V Sinking 1mA VOUT = 5.5V
V mV FA mV FA
Note 1: Limits are 100% production tested at TA = +25NC. Limits over the operating temperature range are guaranteed by design. Note 2: NC includes external NTC thermistor error. % of THMSW excludes thermistor beta error and external pullup error. NTC thermistor assumed to be 100kI Q1% nominal, part number Vishay NTHS0603N01N1003FF, external pullup resistor = 100kI Q1%.
_______________________________________________________________________________________
5
Dual-Input Linear Charger, Smart Power Selector with Advanced Battery Temperature Monitoring MAX8934G
Typical Operating Characteristics
(TA = +25NC, circuit of Figure 2, VDC = 6V, VBATT = 3.6V, thermistor Beta = 3964, unless otherwise noted. Negative battery current indicates charging.)
USB OPERATING SUPPLY CURRENT vs. USB VOLTAGE (CHARGER ENABLED)
MAX8934G toc01
USB OPERATING SUPPLY CURRENT vs. USB VOLTAGE (CHARGER DISABLED)
MAX8934G toc02
USB SUSPEND CURRENT vs. USB VOLTAGE
VBATT = 4.2V, USUS = 1
MAX8934G toc03
1200 USB OPERATIN SUPPLY CURRENT (A) 1000 800 600 400 200
900 USB OPERATING SUPPLY CURRENT (A) 800 700 600 500 400 300 200 100 0 0 1 2 3 4 5 6 7 ENTERING OVLO VUSB RISING VUSB FALLING VBATT = 4.2V, VUSUS = 0V CEN = 1 ISYS = 0A PEN1 = X, PEN2 = 1
250 USB QUIESCENT CURRENT (FA) 200 150 100 50 0
VBATT = 4.2V, VUSUS = 0V CHARGER IN DONE MODE ISYS = 0A VUSB RISING VUSB FALLING
ENTERING OVLO
0 0 1 2 3 4 5 6 7 8 USB VOLTAGE (V)
8
0
1
2
3
4
5
6
7
8
USB VOLTAGE (V)
USB VOLTAGE (V)
BATTERY INPUT CURRENT vs. BATTERY VOLTAGE (USB DISCONNECTED)
MAX8934G toc04
BATTERY INPUT CURRENT vs. TEMPERATURE
MAX8934G toc05
CHARGE CURRENT vs. BATTERY VOLTAGE (100mA USB)
90 80 CHARGE CURRENT (mA) 70 60 50 40 30 20 10 0
MAX8934G toc06
14 BATTERY INPUT CURRENT (uA) 12 THMEN = 1 10 8 6 4 THMEN = 0 2 0 0 1 2 3 4
5.0 4.9 BATTERY INPUT CURRENT (A) 4.8 4.7 4.6 4.5 4.4 4.3 4.2 4.1 4.0 VBATT = 4V, THMEN = 0, ILDO = 0 USB AND DC UNCONNECTED
100
VUSB = 5V PEN1 = X, PEN2 = 0 VBATT RISING VBATT FALLING
5
-40
-15
10
35
60
85
0
1
2
3
4
5
BATTERY VOLTAGE (V)
TEMPERATURE (C)
BATTERY VOLTAGE (V)
CHARGE CURRENT vs. BATTERY VOLTAGE (500mA USB)
MAX8934G toc07
CHARGE CURRENT vs. BATTERY VOLTAGE (1A DC)
VDC = 5V PEN1 = 1, PEN2 = X VBATT RISING VBATT FALLING
MAX8934G toc08
500 450 400 CHARGE CURRENT (mA) 350 300 250 200 150 100 50 0 0 1 2 3 4 VUSB = 5V PEN1 = X, PEN2 = 1 VBATT RISING VBATT FALLING
1200 1000 CHARGE CURRENT (mA) 800 600 400 200 0
5
0
1
2
3
4
5
BATTERY VOLTAGE (V)
BATTERY VOLTAGE (V)
6
______________________________________________________________________________________
Dual-Input Linear Charger, Smart Power Selector with Advanced Battery Temperature Monitoring
Typical Operating Characteristics (continued)
(TA = +25NC, circuit of Figure 2, VDC = 6V, VBATT = 3.6V, thermistor Beta = 3964, unless otherwise noted. Negative battery current indicates charging.)
NORMALIZED CHARGE CURRENT vs. AMBIENT TEMPERATURE (LOW IC POWER DISSIPATION)
MAX8943G toc09
MAX8934G
BATTERY REGULATION VOLTAGE vs. TEMPERATURE
BATTERY REGULATION VOLTAGE (V) 4.215 4.210 4.205 4.200 4.195 4.190 4.185 4.180 4.175 4.170 -40 -15 10 35 60 85 BATTERY VOLTAGE (V)
MAX8934G toc10
1.0100 NORMALIZED CHARGE CURRENT 1.0075 1.0050 1.0025 1.0000 0.9975 0.9950 0.9925 0.9900 -40 -15 10
VUSB = 5V, VBATT = 4V
4.220
35
60
85
AMBIENT TEMPERATURE (C)
SYS OUTPUT VOLTAGE vs. USB VOLTAGE
MAX8934G toc11
SYS OUTPUT VOLTAGE vs. DC VOLTAGE
VBATT = 4.0V NO SYS LOAD 4.6 SYS VOLTAGE (V)
MAX8934G toc12
4.8 VBATT = 4.0V NO SYS LOAD 4.6 SYS VOLTAGE (V)
4.8
4.4
4.4
4.2
4.2
4.0 0 1 2 3 4 5 6 7 8 USB VOLTAGE (V)
4.0 0 2 4 6 8 10 12 14 DC VOLTAGE (V)
SYS OUTPUT VOLTAGE vs. SYS OUTPUT CURRENT (USB AND DC DISCONNECTED)
4.4 SYS OUTPUT VOLTAGE (V) 4.3 4.2 4.1 4.0 3.9 3.8 3.7 3.6 0 0.5 1.0 1.5 2.0 SYS OUTPUT CURRENT (A) 3.5 0.0
SYS OUTPUT VOLTAGE vs. SYS OUTPUT CURRENT (DC)
MAX8934G toc14
VBATT = 4.0V THE SLOPE OF THIS LINE SHOWS THAT THE BATT-TO-SYS RESISTANCE IS 40mI.
MAX8934G toc13
4.5
5.5 5.1 SYS VOLTAGE (V) 4.7 4.3 3.9
VDC = 6V
VBAT = 4V PEN1 = 1, PEN2 = X CEN = 1
VDC = 5V
1.5 2.0 2.5 3.0
0.5
1.0
SYS CURRENT (A)
_______________________________________________________________________________________
7
Dual-Input Linear Charger, Smart Power Selector with Advanced Battery Temperature Monitoring MAX8934G
Typical Operating Characteristics (continued)
(TA = +25NC, circuit of Figure 2, VDC = 6V, VBATT = 3.6V, thermistor Beta = 3964, unless otherwise noted. Negative battery current indicates charging.)
SYS OUTPUT VOLTAGE vs. SYS OUTPUT CURRENT (USB)
MAX8934G toc15
VL OUTPUT VOLTAGE vs. DC VOLTAGE
3.0 VL OUTPUT VOLTAGE (V) 2.5 2.0 1.5 1.0 0.5 0
MAX8934G toc16
5.5 5.3 SYS OUTPUT VOLTAGE (V) 5.1 4.9 4.7 4.5 4.3 4.1 3.9 3.7 3.5 0 0.5 1.0 1.5 2.0 2.5
3.5
VBATT = 4.0V, VUSB = 5.0V CEN = 1 0.1A, PEN1 = 0, PEN2 = 0 0.5A, PEN1 = 0, PEN2 = 0
IVL = 5mA
IVL = 0mA
3.0
0
2
4
6
8
10
12
14
SYS OUTPUT CURRENT (A)
DC VOLTAGE (V)
CHARGE PROFILE--820mAh BATTERY USB INPUT--500mA CHARGE
500 450 BATTERY CURRENT (mA) 400 350 300 250 200 150 100 50 0 0 20 40 60 TIME (min) 80 100 VBAT IBAT
CHARGE PROFILE--820mAh BATTERY ADAPTER INPUT--1A CHARGE
4.5 4.0 BATTERY VOLTAGE (V) 3.5 3.0 2.5 1.2 1.0 BATTERY CURRENT (mA) 0.8 IBAT 0.6 0.4 0.2 0 0 20 40 TIME (min) 60 80 3.0 2.5 2.0 1.5
MAX8934G toc18
MAX8934G toc17
4.5 4.0 3.5 BATTERY VOLTAGE (V)
VBAT
2.0 120
DC CONNECT WITH USB CONNECTED (RSYS = 22I)
VSYS 3.8V CDC CHARGING IDC 0A 4.35V CSYS CHARGING 1.2A
DC CONNECT WITH NO USB (RSYS = 22I)
5V/div 1A/div VBATT VSYS 3.6V 3.6V CDC CHARGING IDC 0A 4.35V CSYS CHARGING
MAX8934G toc19
MAX8934G toc20
5V/div 5V/div 1.2A
1A/div
IUSB
475mA 0A
500mA/div 160mA 1A/div -1A IBATT BATTERY CHARGER SOFT-START 400s/div 0mA -1A 1A/div
IBATT
-303mA BATTERY CHARGER SOFT-START 400s/div
8
______________________________________________________________________________________
Dual-Input Linear Charger, Smart Power Selector with Advanced Battery Temperature Monitoring
Typical Operating Characteristics (continued)
(TA = +25NC, circuit of Figure 2, VDC = 6V, VBATT = 3.6V, thermistor Beta = 3964, unless otherwise noted. Negative battery current indicates charging.)
DC DISCONNECT WITH NO USB (RSYS = 22I)
VBATT VSYS 4V IDC 1.2A 0A 3.6V 3.6V
MAX8934G
MAX8934G toc21
USB CONNECT WITH NO DC (RSYS = 22I)
5V/div 5V/div 1A/div VSYS VUOK 3.3V 3.3V 3.3V -150mA 4.3V VUSB IUSB 5V 475mA CSYS CHARGING CDC CHARGING
MAX8934G toc22
5V/div 500mA/div
3.7V
5V/div 5V/div
160mA IBATT -1A -IBATT = CHARGING 200s/div 1A/div
VCHG IBATT
BATTERY CHARGER -1A SOFT-START -307mA 200s/div
5V/div 500mA/div
USB DISCONNECT WITH NO DC (RSYS = 22I)
VUSB IUSB 475mA 0mA VSYS VUOK VCHG IBATT -307mA 3.7V 3.6V 3.3V 3.3V 160mA 200s/div 4.2V 0V
MAX8934G toc23
USB SUSPEND (RSYS = 22I)
5V/div 500mA/div VUSUS IUSB VSYS 5V/div 5V/div 5V/div 500mA/div VCHG IBATT -307mA 200s/div 0V 475mA 3.3V 0A
MAX8934G toc24
5V/div 500mA/div 5V/div 5V/div
3.7V
3.6V 3.3V 160mA VUSB = 5V
500mA/div
USB RESUME (RSYS = 22I)
VUSUS IUSB 3V 0A 3.6V VSYS VCHG 3.3V 160mA 4.3V 0V
MAX8934G toc25
LDO OUTPUT VOLTAGE vs. LDO OUTPUT CURRENT (USB DISCONNECTED)
5V/div 500mA/div 5V/div
3.30 LDO OUTPUT VOLTAGE (V) 3.25 3.20 3.15 3.10 3.05 3.00 2.95 0
VBATT = 4.0V
475mA 3.7V
DC UNCONNECTED VDC = 5.0V
BATTERY CHARGER SOFT-START -307mA VUSB = 5V 200s/div
5V/div
IBATT
500mA/div
25
50 75 100 125 150 LDO OUTPUT CURRENT (mA)
175
_______________________________________________________________________________________
MAX8934G toc26
3.35
9
Dual-Input Linear Charger, Smart Power Selector with Advanced Battery Temperature Monitoring MAX8934G
Typical Operating Characteristics (continued)
(TA = +25NC, circuit of Figure 2, VDC = 6V, VBATT = 3.6V, thermistor Beta = 3964, unless otherwise noted. Negative battery current indicates charging.)
LDO OUTPUT VOLTAGE vs. BATTERY VOLTAGE
3.0 LDO OUTPUT VOLTAGE (V) 2.5 2.0 1.5 1.0 0.5 400Fs/div 0 0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 BATTERY VOLTAGE (V)
MAX8934G toc28
LDO STARTUP WAVEFORMS
MAX8934G toc27
ILDO = 0 VBATT
3.5 2V/div 2V/div
3.6V
VLDO
3.3V
VBATT FALLING VBATT RISING
IBATT
50mA/div
ALWAYS-ON LDO POWER-SUPPLY REJECTION RATIO vs. FREQUENCY
MAX8934G toc29
LDO NOISE DENSITY vs. FREQUENCY
800 OUTPUT NOISE (nV/Hz) 700 600 500 400 300 200 100 0 VBATT = 3.8V, ILDO = 10mA RESISTIVE LOAD
MAX8934G toc30
0 -5 -10 -15 PSRR (dB) -20 -25 -30 -35 -40 -45 -50 0.1 1 10 VSYS = 3.6V ILDO = 10mA RESISTIVE LOAD
900
100
0.01
0.1
1
10
100
1000 10,000
FREQUENCY (kHz)
FREQUENCY (kHz)
THM NORMAL TO THM COLD (< T2) TRANSITION
MAX8934G toc31
1V/div VTHM 2.2V 4.2V VBAT 4.075V 200mV/div
420mA IBAT
10I RESISTOR FROM BATT TO GND
200mA/div
10ms/div
10
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Dual-Input Linear Charger, Smart Power Selector with Advanced Battery Temperature Monitoring
Typical Operating Characteristics (continued)
(TA = +25NC, circuit of Figure 2, VDC = 6V, VBATT = 3.6V, thermistor Beta = 3964, unless otherwise noted. Negative battery current indicates charging.)
THM NORMAL TO THM HOT (> T3) TRANSITION
MAX8934G toc32
MAX8934G
THM NORMAL TO THM HOT NO CHARGE (> T4) TRANSITION
MAX8934G toc33
0.65V
VTHM 500mV/div VTHM 500mV/div
1.0V
VBATT
4.2V 4.075V
200mV/div 500mA/div VBATT
4.075V 0V
2V/div
4.2V
IBATT
940mA HP6060B ELECTRONIC LOAD SET TO CC MODE
10ms/div
IBATT
100mA 0mA HP6060B ELECTRONIC LOAD SET TO CC MODE
20ms/div 100mA/div
THM NORMAL TO THM HOT THRESHOLD DISCHARGE TOT
VTHM VOT
THM NORMAL TO T2 TO T1 (COLD, NO CHARGE) TRANSITION
MAX8934G toc35
MAX8934G toc34
2V/div
2.2V VTHM 4.2V 2.54V 4.075V
1V/div
3V
0.425V
2V/div
VBATT VBATT
1V/div
3.6V
2V/div 420mA 0V 200mA/div 0mA 4ms/div 10ms/div
VSYS
3.6V
2V/div
IBATT
10I RESISTOR FROM BATT TO GND
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11
Dual-Input Linear Charger, Smart Power Selector with Advanced Battery Temperature Monitoring MAX8934G
Pin Description
PIN 1 NAME DONE FUNCTION Charge Complete Output. The DONE active-low, open-drain output pulls low when the charger enters the DONE state. The charger current = 0mA when DONE is low. See Figure 7. DC Power Input. DC is capable of delivering up to 2A to SYS. DC supports both AC adapter and USB inputs. The DC current limit is set with PEN1, PEN2, and RPSET. See Table 2. Both DC pins must be connected together externally. Connect a 10FF ceramic capacitor from DC to GND. The DC inputs should be grounded if not used. Active-Low Charger Enable Input. Connect CEN to GND or drive low with a logic signal to enable battery charging when a valid source is connected at DC or USB. Drive high with a logic signal to disable battery charging. Input Limit Control 1. See Table 2 for complete information. Input Limit Control 2. See Table 2 for complete information. DC Input Current-Limit Setting. Connect a resistor from PSET to GND to program the DC current limit up to 2A (3000V/RPSET). Internal Logic LDO Output Bypass Pin. Provides 3.3V when DC or USB is present. Connect a 0.1FF ceramic capacitor from VL to GND. VL powers the internal circuitry and provides up to 5mA to an external load. Ground. Both GND pins must be connected together externally. Charge Timer Program Input. A capacitor from CT to GND sets the maximum prequal and fast-charge timers. Connect CT to GND to disable the timer. Charge Current-Limit Setting. A resistor (RISET) from ISET to GND programs the fast-charge charge current up to 1.5A (3000V/RISET). The prequal charge current is 20% of the set fast-charge charge current. USB Suspend Digital Input. As shown in Table 2, driving USUS high suspends the DC or USB inputs if they are configured as a USB power input. Thermistor Input. Connect a negative temperature coefficient (NTC) thermistor with good thermal contact with the battery from THM to GND. Use a thermistor with Beta = 3964. Connect a resistor of equal resistance to the thermistor resistance at +25C from THM to THMSW so that the battery temperature can be monitored, and the fast-charge current and/or the charge termination voltage is automatically adjusted, in accordance with safety region 2 of the JEITA specification. Thermistor Enable Input. THMEN controls THMSW by connecting the external thermistor pullup resistor and the thermistor monitoring circuit to LDO. Drive THMEN high to enable the thermistor circuit in discharge mode and to connect the external thermistor pullup resistor. Drive THMEN low to disconnect the external thermistor pullup resistor and to disable the thermistor monitoring circuit to conserve battery energy when not charging. Thermistor Pullup Supply Switch. Drive THMEN high to enable the THMSW, shorting the THMSW output to LDO. Drive THMEN low to open the THMSW switch. THMSW is always on when a valid input source is present and the battery is being charged. When no input source is present, THMSW is controlled by THMEN. THMSW is also active when the battery is being discharged, so that the battery temperature can be monitored for an overtemperature condition.
2, 3
DC
4 5 6 7
CEN PEN1 PEN2 PSET
8 9, 13 10
VL GND CT
11
ISET
12
USUS
14
THM
15
THMEN
16
THMSW
12
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Dual-Input Linear Charger, Smart Power Selector with Advanced Battery Temperature Monitoring
Pin Description (continued)
PIN NAME FUNCTION Always-On Linear Regulator Output. LDO is the output of an internal always-on 3.3V LDO that provides power to external circuitry. The LDO output provides up to 30mA of current for indicator LEDs or other loads. LDO remains active even when only a battery is present, so that the thermistor monitor circuitry can be activated when the battery is being discharged, and other circuitry can remain powered. Connect a 1FF ceramic capacitor from LDO to GND. USB Power Input. USB is capable of delivering up to 0.5A to SYS. The USB current limit is set with PEN2 and USUS. See Table 2. Both USB pins must be connected together externally. Connect a 4.7FF ceramic capacitor from USB to GND. Battery Connection. Connect the positive terminal of a single-cell Li+ battery to BATT. The battery charges from SYS when a valid source is present at DC or USB. BATT powers SYS when neither DC nor USB power is present, or when the SYS load exceeds the input current limit. Both BATT pins must be connected together externally. Charger Status Output. The CHG active-low, open-drain output pulls low when the battery is in fast charge or prequal. Otherwise, CHG is high impedance. System Supply Output. SYS is connected to BATT through an internal 40mI system load switch when DC or USB are invalid, or when the SYS load is greater than the input current limit. When a valid voltage is present at DC or USB, SYS is limited to or 4.35V. When the system load (ISYS) exceeds the DC or USB current limit, SYS is regulated to 75mV below VBATT and both the input and the battery service the SYS load. Bypass SYS to GND with a 10FF ceramic capacitor. Both SYS pins must be connected together externally. Battery Overtemperature Flag. The OT active-low, open-drain output pulls low when THMEN is high and the battery temperature is R +75NC. DC Power-OK Output. The DOK active-low, open-drain output pulls low when a valid input is detected at DC. USB Power-OK Output. The UOK active-low, open-drain output pulls low when a valid input is detected at USB. Fault Output. The FLT active-low, open-drain output pulls low when the battery timer expires before prequal or fast charge complete. Exposed Pad. Connect the exposed pad to GND. Connecting the exposed pad does not remove the requirement for proper ground connections to the appropriate pins.
MAX8934G
17
LDO
18, 19
USB
20, 21
BATT
22
CHG
23, 24
SYS
25 26 27 28 --
OT DOK UOK FLT EP
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13
Dual-Input Linear Charger, Smart Power Selector with Advanced Battery Temperature Monitoring MAX8934G
OT DC DC DC POWER MANAGEMENT
LDO
SYS SYS Li+ BATTERY CHARGER AND SYS LOAD SWITCH
PWR OK
3.3V ALWAYS-ON LOW-IQ LDO CURRENTLIMITED VOLTAGE REGULATOR
DOK
CHARGER CURRENT AND VOLTAGE CONTROL
ISET BATT BATT
SET INPUT LIMIT
VL
VL LDO FOR IC POWER USB POWER MANAGEMENT
THERMISTOR MONITOR (SEE FIGURE 5) THM THMSW
T
USB
PWR OK CURRENTLIMITED VOLTAGE REGULATOR CHG CHARGE TERMINATION AND MONITOR
THMEN THERMAL REGULATION
UOK
CHG DONE FLT
SET INPUT LIMIT PEN1 PEN2 USUS PSET GND EP INPUT AND CHARGER CURRENT-LIMIT LOGIC CONTROL CHARGE TIMER
CT
MAX8934G
CEN
Figure 1. Block Diagram
14
_____________________________________________________________________________________
Dual-Input Linear Charger, Smart Power Selector with Advanced Battery Temperature Monitoring MAX8934G
TO LDO RPU 1MI CHARGE DONE ADAPTER CDC 10FF 1 DONE OT 25 28 27 26 RPU 4x 1MI OVERTEMPERATURE FAULT OUTPUT USB PWR OK DC PWR OK
MAX8934G
2 DC 3 DC 5 PEN1 CEN PEN2 PSET
FLT UOK DOK
OFF CHARGE ON 500mA 100mA RPSET 1.5kI
4 6 7
SYS 23 SYS 24 1MI CHG 22 LDO CSYS 10FF
TO SYSTEM LOAD
CHARGE INDICATOR
11 RISET 3kI CVL 0.1FF 9, 13 CCT 0.068FF THMSW ACTIVE DISABLED 10 15 16 14 100kI NTC 100kI 25C
ISET
BATT 20 BATT 21 CBATT 4.7FF 1-CELL Li+
8
VL
GND CT THMEN THMSW THM EP
USB 18 USB 19 17 CLDO 1FF 12 CUSB 4.7FF
1 2 3 4 5
VBUS DD+ ID GND
LDO
USUS
USB SUSPEND
Figure 2. Typical Application Circuit Using Separate DC and USB Connector
______________________________________________________________________________________
15
Dual-Input Linear Charger, Smart Power Selector with Advanced Battery Temperature Monitoring MAX8934G
TO LDO RPU 1MI 1 DONE RPU 4x 1MI
5-PIN USB CONNECTOR VBUS DD+ ID GND 1 2 3 4 5
CHARGE DONE
2 DC CDC 10FF 3 DC
MAX8934G
OT FLT UOK DOK
25 28 27 26
OVERTEMPERATURE FAULT OUTPUT USB PWR OK DC PWR OK
OFF CHARGE ON DC USB 500mA 100mA RPSET 1.5kI
4 5 6 7
CEN PEN1
SYS 23 SYS 24 1MI CHG 22 CSYS 10FF VLDO
TO SYSTEM LOAD
PEN2 PSET
CHARGE INDICATOR
BATT 20 BATT 21 CBATT 4.7FF 1-CELL Li+
11 RISET 3kI CVL 0.1FF CCT 0.068FF THMSW ACTIVE DISABLED
ISET USB 18 VL USB 19 GND CT THMEN THMSW THM EP 12 LDO 17 CLDO 1FF USB SUSPEND
8
9, 13 10 15 16 14
USUS
100kI
NTC 100kI 25C
Figure 3. Typical Application Circuit Using a 5-Pin USB Connector or Other DC/USB Common Connector
16
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Dual-Input Linear Charger, Smart Power Selector with Advanced Battery Temperature Monitoring
Table 1. External Components List for Figures 2 and 3
COMPONENT (Figures 2 and 3) CDC CUSB CVL CSYS CBATT CCT CLDO RPU (x5) THM RTHMSW RPSET RISET FUNCTION DC filter capacitor USB filter capacitor VL filter capacitor SYS output bypass capacitors Battery bypass capacitor Charger timing capacitor LDO output capacitor Logic-output pullup resistors Negative TC thermistor THM pullup resistor DC input current-limit programming resistor Fast-charge current programming resistor PART NUMBER 10FF 10%, 16V X5R ceramic capacitor (0805) Taiyo Yuden EMK212BJ106KG 4.7FF 10%, 10V X5R ceramic capacitor (0805) Taiyo Yuden LMK212BJ475KD 0.1FF 10%, 10V X5R ceramic capacitor (0402) Taiyo Yuden LMK105BJ104KV 10FF 10%, 6.3V X5R ceramic capacitor (0805) Taiyo Yuden JMK212BJ106KD 4.7FF 10%, 6.3V X5R ceramic capacitor (0805) Taiyo Yuden JMK212BJ475KD 0.068FF 10%, 16V X5R ceramic capacitor (0402) Taiyo Yuden EMK105BJ683KV 1FF 10%, 6.3V X5R ceramic capacitor (0402) Taiyo Yuden JMK105BJ105KV 1MI 5% resistor Vishay NTC Thermistor P/N NTHS0603N01N1003FF 100kI 1.5kI 1% for 2A limit 3kI 1% for 1A charging
MAX8934G
Detailed Description
The MAX8934G is a dual-input linear charger with Smart Power Selector that safely charges a single Li+/Li-Poly cell in accordance with JEITA specifications. The MAX8934G integrates power MOSFETs and control circuitry to manage power flow in portable devices. See Figure 1. The charger has two power inputs, DC and USB. These can be separately connected to an AC adapter output and a USB port, or the DC input could be a single power input that connects to either an adapter or USB. Logic inputs, PEN1 and PEN2, select the correct current limits for two-input or single-input operation. Figure 2 is the typical application circuit using separate DC and USB connectors. Figure 3 is the typical application circuit using a 5-pin USB connector or another DC/USB common connector. In addition to charging the battery, the MAX8934G also supplies power to the system through the SYS output. The charging current is also provided from SYS so that the set input current limit controls the total SYS current, where total SYS current is the sum of the system load current and the battery-charging current. SYS is powered from either the DC input pin or the USB input pin. If both the DC and USB sources are connected, DC takes precedence.
In some instances, there may not be enough adapter current or USB current to supply peak system loads. The MAX8934G Smart Power Selector circuitry offers flexible power distribution from an AC adapter or USB source to the battery and system load. The battery is charged with any available power not used by the system load. If a system load peak exceeds the input current limit, supplemental current is taken from the battery. Thermal limiting prevents overheating by reducing power drawn from the input source. The MAX8934G features an overvoltage limiter at SYS. If the DC or USB input voltage exceeds the SYS regulation voltage, VSYS does not follow VDC or VUSB, but remains at its regulation voltage. The MAX8934G has numerous other charging and power-management features that are detailed in the following sections. A 3.3V ultra-low quiescent current, always-on LDO provides up to 30mA for indicator LEDs and for backup power to the system. This LDO powers the thermistor monitor circuitry and provides bias to the external pullup resistor for the thermistor.
______________________________________________________________________________________
17
Dual-Input Linear Charger, Smart Power Selector with Advanced Battery Temperature Monitoring MAX8934G
The MAX8934G Smart Power Selector seamlessly distributes power among the external inputs, the battery, and the system load (see the Typical Operating Circuit). The basic functions performed are: U With both an external power supply (USB or adapter) and battery connected: U When the system load requirements are less than the input current limit, the battery is charged with residual power from the input. U When the system load requirements exceed the input current limit, the battery supplies supplemental current to the load. U When the battery is connected and there is no external power input, the system is powered from the battery. U When an external power input is connected and there is no battery, the system is powered from the external power input. An internal 40mI MOSFET connects SYS to BATT (Q3 in the Typical Operating Circuit) when no voltage source is available at DC or USB. When an external source is detected at DC or USB, this switch is opened and SYS is powered from the valid input source through the input limiter. The SYS-BATT switch also holds up SYS when the system load exceeds the input current limit. If that should happen, the SYS-BATT switch turns on so that the battery supplies additional SYS load current. If the system load continuously exceeds the input current limit, the battery does not charge, even though external power is connected. This is not expected to occur in most cases, since high loads usually occur only in short peaks. During these peaks, battery energy is used, but at all other times the battery charges. The input voltage limiter is essentially an LDO regulator. While in dropout, the regulator dissipates a small I2R loss through the 0.2I MOSFET (Q1 in the Typical Operating Circuit) between DC and SYS. With an AC adapter or USB source connected, the input limiter distributes power from the external power source to the system load and battery charger. In addition to the input limiter's primary function of passing power to the system and charger loads at SYS, it performs several additional functions to optimize use of available power.
Smart Power Selector
Input Voltage Limiting If an input voltage is above the overvoltage threshold (6.9V typ), the MAX8934G enters overvoltage lockout (OVLO). OVLO protects the MAX8934G and downstream circuitry from high-voltage stress up to 14V at DC and 8V at USB. In OVLO, VL remains on, the input switch that sees overvoltage (Q1, Q2, Typical Operating Circuit) opens, the appropriate power-monitor output (DOK, UOK) is high impedance, and CHG is high impedance. If both DC and USB see overvoltage, both input switches (Q1 and Q2, Typical Operating Circuit) open and the charger turns off. The BATT-to-SYS switch (Q3, Typical Operating Circuit) closes, allowing the battery to power SYS. An input is also invalid if it is less than BATT, or less than the DC undervoltage threshold of 3.5V (falling). With an invalid input voltage, SYS connects to BATT through a 40mI switch (Q3, Typical Operating Circuit). Input Overcurrent Protection The current at DC and USB is limited to prevent input overload. This current limit can be selected to match the capabilities of the source, whether it is a 100mA or 500mA USB source, or an AC adapter. When the load exceeds the input current limit, SYS drops to 75mV below BATT and the battery supplies supplemental load current. Thermal Limiting The MAX8934G reduces input limiter current by 5%/NC when its die temperature exceeds +100NC. The system load (SYS) has priority over the charger current, so lowering the charge current first reduces the input current. If the junction temperature still reaches +120NC in spite of charge current reduction, no input (DC or USB) current is drawn, the battery supplies the entire system load, and SYS is regulated at 75mV below BATT. Note that this on-chip thermal-limiting circuitry is not related to and operates independently from the thermistor input. Adaptive Battery Charging While the system is powered from DC, the charger draws power from SYS to charge the battery. If the charger load plus system load exceeds the input current limit, an adaptive charger control loop reduces charge current to prevent the SYS voltage from collapsing. Maintaining a higher SYS voltage improves efficiency and reduces power dissipation in the input limiter. The total current through the switch (Q1 or Q2 in the Typical Operating Circuit) is the sum of the load current at SYS and the battery charging current. The MAX8934G limiter clamps at 4.35V, so input voltages greater than 4.35V can increase power dissipation in the limiter. The MAX8934G input
System Load Switch
Input Limiter
18
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Dual-Input Linear Charger, Smart Power Selector with Advanced Battery Temperature Monitoring
limiter power loss is (VDC - VSYS) x IDC, where VSYS may be as high as 4.35V. The input limiter power loss is not less than 0.2I x IDC2. Also note that the MAX8934G turns off when any input exceeds 6.9V (typ). When the AC adapter and USB have separate connectors, the adapter output connects to DC and the USB source connects to USB. PEN1 is permanently connected high (to DC or VL). The DC current limit is set by RPSET, while the USB current limit is set by PEN2 and USUS.
Separate Adapter and USB Connectors
MAX8934G
DC and USB Connections and Current-Limit Options
Input Current Limit The input and charger current limits are set as shown in Table 2. It is often preferable to change the input current limit as the input power source is changed. The MAX8934G facilitates this by allowing different input current limits for DC and USB as shown in Table 2. When the input current limit is reached, the first action taken by the MAX8934G is to reduce the battery charge current. This allows the regulator to stay in dropout during heavy loads, thus reducing power dissipation. If, after the charge current is reduced to 0mA, the load at SYS still exceeds the input current limit, SYS voltage begins to fall. When the SYS voltage drops to BATT, the SYSto-BATT switch turns on, using battery power to support the system load during the load peak. The MAX8934G features flexible input connections (at the DC and USB input pins) and current-limit settings (set by PEN1, PEN2, PSET, and ISET) to accommodate nearly any input power configuration. However, it is expected that most systems use one of two external power schemes: separate connections for USB and an AC adapter, or a single connector that accepts either USB or AC adapter output. Input and charger current limit are controlled by PEN1, PEN2, RPSET, and RISET, as shown in Table 2.
When a single common connector is used for both AC adapter and USB sources, the DC input is used for both input sources. The unused USB inputs should be grounded when an AC adapter is connected at DC, PEN1 should be pulled high to select the current limit set by RPSET. When a USB source is connected, PEN1 should be low to select 500mA, 100mA, or USB suspend (further selected by PEN2 and USUS). PEN1 can be pulled up by the AC adapter power to implement hardware adapter/USB selection. Driving USUS high when PEN1 is low turns off the charger and reduces input current to 190FA to accommodate USB suspend mode. The input limiter is disabled and SYS is supported by BATT. DOK is an open-drain output that pulls low when the DC input has valid power. UOK is an open-drain output that pulls low when the USB input has valid power. A valid input for DC or USB is between 4.1V and 6.6V. If a single power-OK output is preferred, DOK and UOK can be wire-ORed together. The combined output then pulls low if either USB or DC is valid.
Single Common Connector for USB or Adapter
USB Suspend
Power Monitor Outputs (UOK, DOK)
Table 2. Input Limiter Control Logic
POWER SOURCE AC adapter at DC input USB power at DC input USB power at USB input; DC unconnected DC and USB unconnected DOK L L L L H H H H UOK X X X X L L L H PEN1 H L L L X X X X PEN2 X H L X H L X X USUS X L L H L L H X No DC input DC INPUT CURRENT LIMIT 3000V/RPSET 475mA 95mA USB suspend 475mA 95mA USB suspend No USB input USB INPUT CURRENT LIMIT USB input off; DC input has priority MAXIMUM CHARGE CURRENT* 3000V/RISET 475mA 95mA 0 3000V/RISET 0 0
*Charge current cannot exceed the input current limit. Actual charge current may be less than the maximum charge current if the total SYS load exceeds the input current limit. ______________________________________________________________________________________ 19
Dual-Input Linear Charger, Smart Power Selector with Advanced Battery Temperature Monitoring MAX8934G
To prevent input transients that can cause instability in the USB or AC adapter power source, the rate of change of input current and charge current is limited. When a valid DC or USB input is connected, the input current limit is ramped from zero to the set current-limit value (as shown in Table 2). If DC is connected with no USB power present, input current ramps in 1.5ms. If DC is connected with USB already present, input current ramps in 50Fs. When USB is connected with no DC present, input current also ramps in 50Fs. If USB is connected with DC already present, the USB input is ignored. If an adapter is plugged into DC while USB is already powered, the input current limit reramps from zero back up to the DC current limit so that the AC adapter does not see a load step. During this transition, if the input current limit is below the SYS load current, the battery supplies the additional current needed to support the load. Additionally, capacitance can be added to SYS to support the load during input power transitions. When the charger is turned on, charge current ramps from zero to the ISET current value in 1.5ms. Charge current also ramps when transitioning to fast-charge from prequal and when changing the USB charge current from 100mA to 500mA with PEN2. There is no dI/dt limiting, however, if ISET is changed suddenly using a switch at RISET. The battery charger state diagram is illustrated in Figure 7. With a valid DC or USB input, the battery charger initiates a charge cycle when the charger is enabled. It first detects the battery voltage. If the battery voltage is less than the BATT prequal threshold (3.0V), the charger enters prequal mode and charges the battery at 20% of the maximum fast-charge current. This reduced charge rate ensures that the maximum fast-charge current setting does not damage a deeply discharged battery. Once the battery voltage rises to 3.0V, the charger transitions to fast-charge mode and applies the maximum charge current. As charging continues, the battery voltage rises until it approaches the battery regulation voltage where charge current starts tapering down. When charge current decreases to 20% of the fast-charge current, the charger enters a brief 15s top-off state, then DONE pulls low and charging stops. If the battery voltage subsequently drops below the recharge threshold, charging restarts and the timers reset.
Soft-Start
When CEN is low, the charger is on. When CEN is high, the charger turns off. CEN does not affect the SYS output. In many systems, there is no need for the system controller (typically a microprocessor) to disable the charger, because the MAX8934G Smart Power Selector circuitry independently manages charging and adapter/ battery power hand-off. In these situations, CEN can be connected to ground. ISET adjusts charge current to match the capacity of the battery. A resistor from ISET to ground sets the maximum fast-charge current: ICHGMAX = 2000 x 1.5V/RISET = 3000V/RISET Determine the ICHGMAX value by considering the characteristics of the battery. It is not necessary to limit the charge current based on the capabilities of the expected AC adapter/USB charging input, the system load, or thermal limitations of the PCB. The MAX8934G automatically adjusts the charging algorithm to accommodate these factors. In addition to setting the charge current, ISET can also be used to monitor the actual current charging the battery. See Figure 4. The ISET output voltage is: VISET = ICHG x 1.5V/ICHGMAX = ICHG x RISET/2000 where ICHGMAX is the set fast-charge current and ICHG is the actual battery charge current. A 1.5V output indicates the battery is being charged at the maximum set fast charge current; 0V indicates no charging. This voltage is also used by the charger control circuitry to set and monitor the battery current. Avoid adding more than 10pF capacitance directly to the ISET pin. If filtering of the charge-current monitor is necessary, add a resistor of 100kI or more between ISET and the filter capacitor to preserve charger stability. Note that the actual charge current can be less than the set fast-charge current when the charger enters voltage mode or when the input current limiter or thermal limiter reduces charge current. This prevents the charger from overloading the input source or overheating the system. When the charge current falls to the termination threshold and the charger is in voltage mode, charging is complete. Charging continues for a brief 15s top-off period and then enters the DONE state where charging stops. The DONE current threshold (IDONE) is set to 20% of the
Charge Enable (CEN)
Setting the Charge Current
Monitoring the Charge Current
Battery Charger
Charge Termination
20
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Dual-Input Linear Charger, Smart Power Selector with Advanced Battery Temperature Monitoring
MONITORING THE BATTERY CHARGE CURRENT WITH VISET
1.5
VISET
charge-termination threshold (IDONE) and the charger is in voltage mode. The charger exits the DONE state, and fast-charge resumes, if the battery voltage subsequently drops 104mV, or if input power or CEN is cycled. When the MAX8934G is used in conjunction with a FP, connect a pullup resistor between DONE and the logic I/O voltage to indicate charge status to the FP. Alternatively, DONE can sink up to 20mA for an LED indicator. Fault Output (FLT) and Charge Timer FLT is an open-drain, active-low output that goes low during a battery fault. The fault state occurs when either the prequal or fast-charge timer expires. The prequal and fast-charge fault timers are set by CCT:
PREQUAL: t PQ = 180min x C CT 0.068FF
MAX8934G
VISET (V)
0
DISCHARGING
0 BATTERY CHARGING CURRENT (A)
2000 (1.5V/RISET)
FAST CHARGE: t FC = 300min x
C CT 0.068FF
Figure 4. Monitoring the Battery Charge Current with VISET
TOP - OFF:t TO = 15s
While in fast-charge mode, a large system load or device self-heating can cause the MAX8934G to reduce charge current. Under these circumstances, the fast-charge timer adjusts to ensure that adequate charge time is still allowed. Consequently, the fast-charge timer is slowed by 2x if charge current is reduced below 50% of the programmed fast-charge level. If charge current is reduced to below 20% of the programmed level, the fast-charge timer is paused. The fast-charge timer is not adjusted if the charger is in voltage mode where charge current reduces due to current tapering under normal charging. To exit a fault state, toggle CEN or remove and reconnect the input source(s). Note also that thermistor out of range or on-chip thermal-limit conditions are not considered faults. When the MAX8934G is used in conjunction with a FP, connect a pullup resistor between FLT and the logic I/O voltage to indicate fault status to the FP. Alternatively, FLT can sink up to 20mA for an LED indicator. The MAX8934G thermistor monitor is configured to execute JEITA recommendations regarding Li+/Li-Poly battery charging by adjusting the fast charge current and/or the charge termination voltage accordingly (see Figure 6 ). Connect the THM input to an external negative temperature coefficient (NTC) thermistor to monitor battery or system temperature. Since the thermistor monitoring circuit employs an external bias resistor from THM to THMSW, the thermistor is not limited only to 10kI (at
21
fast-charge current setting. Note that if charge current falls to IDONE as a result of the input or thermal limiter, the charger does not enter the DONE state. For the charger to enter the DONE state, the charge current must be less than IDONE, the charger must be in voltage mode, and the input or thermal limiter must not be reducing the charge current. The charger exits the DONE state, and fast-charge resumes if the battery voltage subsequently drops 104mV or if CEN is cycled.
Charge Status Outputs
Charge Output (CHG) CHG is an open-drain, active-low output that is low during charging. CHG is low when the battery charger is in its prequalification and fast-charge states. When charge current falls to the charge termination threshold (IDONE) and the charger is in voltage mode, CHG goes high impedance. CHG goes high impedance if the thermistor causes the charger to enter temperature suspend mode. When the MAX8934G is used with a microprocessor (FP), connect a pullup resistor between CHG and the logic I/O voltage to indicate charge status to the FP. Alternatively, CHG can sink up to 20mA for an LED indicator. Charge DONE Output (DONE) DONE is an open-drain, active-low output that goes low when charging is complete. The charger enters its DONE state 15s after the charge current falls to the
Thermistor Monitor
______________________________________________________________________________________
Dual-Input Linear Charger, Smart Power Selector with Advanced Battery Temperature Monitoring MAX8934G
+25NC). Any thermistor resistance can be used as long as the value of RTHMSW is equivalent to the thermistor's +25NC resistance. The MAX8934G THM thresholds are optimized for a thermistor Beta of 3964. The general relation of thermistor resistance to temperature is defined by the following equation: R T = R 25 where: RT = The resistance in ohms of the thermistor at temperature T in NC R25 = The resistance in ohms of the thermistor at +25NC A = The material constant of the thermistor T = The temperature of the thermistor in NC Charging is suspended when the thermistor temperature is out of range (VTHM_T1 < VTHM or VTHM < VTHM_T4). The charge timers are also suspended and hold their state but no fault is indicated. When the thermistor comes back into range, charging resumes and the charge timer continues from where it left off. The THMEN input controls THMSW and the thermistor monitor circuitry when the battery charger is disabled, providing the user with the means to minimize the battery current drain caused by the thermistor monitor. The THMEN input is ignored while the battery is charging, since the thermistor must be monitored at all times. While charging, the thermistor monitor is used to automatically adjust the charge termination voltage and/or
1 1 T + 273C 298C xe
the fast-charge current, depending on the sensed battery temperature. If the battery temperature exceeds the THM hot overtemperature threshold and THMEN is high, the OT flag pulls low. Typical systems connect OT to a FP input so that the system can safely shut down. The ultra-low quiescent current LDO is always on and is preset to an output voltage of 3.3V. The LDO provides up to 30mA output current. When DC and USB are invalid and the battery is discharging, the LDO output voltage tracks VSYS as it drops below 3.3V. A 1FF ceramic capacitor connected from LDO to GND is recommended for most applications.
Always-On LDO
Good design minimizes ground bounce and voltage gradients in the ground plane. GND should connect to the power-ground plane at only one point to minimize the effects of power-ground currents. Battery ground should connect directly to the power-ground plane. Connect GND to the exposed pad directly under the IC. Use multiple tightly spaced vias to the ground plane under the exposed pad to help cool the IC. Position input capacitors from DC, SYS, BATT, and USB to the power-ground plane as close as possible to the IC. Keep high current traces such as those to DC, SYS, and BATT as short and wide as possible. Refer to the MAX8934A Evaluation Kit for a suitable PCB layout example.
Power Dissipation PCB Layout and Routing
Table 3. Package Thermal Characteristics
28-PIN 4mm x 4mm THIN QFN SINGLE-LAYER PCB Continuous Power Dissipation BJA BJC 1666.7mW (derate 20.8mW/NC above +70NC) 48NC/W 3NC/W MULTILAYER PCB 2285.7mW (derate 28.6mW/NC above +70NC) 35NC/W 3NC/W
22
_____________________________________________________________________________________
Dual-Input Linear Charger, Smart Power Selector with Advanced Battery Temperature Monitoring MAX8934G
SYS
LOW-IQ, ALWAYS-ON 3.3V LDO LDO TRACKS SYS WHEN DC AND USB ARE NOT PRESENT, THE BATTERY IS BEING DISCHARGED, AND VBATT P 3.3V.
CHG
VINT CHG CHG CHARGER CONTROL T4 (60NC) THMEN THMSW RTHMSW
+
VINT VINT T3 (45NC) VINT
THM
OT THERMISTOR MONITOR
CHG
T
+
CHG VINT VINT T2 (10NC)
+ CHG VINT VINT
TOT (75NC)
+
NOT CHARGING THMEN VINT VINT T1 (0NC)
+ CHG
Figure 5. Thermistor Monitor Details ______________________________________________________________________________________ 23
Dual-Input Linear Charger, Smart Power Selector with Advanced Battery Temperature Monitoring MAX8934G
T1 BATT REGULATION VOLTAGE (V) (VBATT_REG) T2 T3 T4
4.2 4.1 4.075 4.0 0 10 25 45 60 TEMPERATURE (NC) T3 T4 85
C FAST-CHARGE CURRENT (ICHG)
T1
T2
0.5C
0
10
25
45 TEMPERATURE (NC)
60
85
Figure 6. Safety Region 2: Fast-Charge Currents and Charge Termination Voltages
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Dual-Input Linear Charger, Smart Power Selector with Advanced Battery Temperature Monitoring MAX8934G
NOT READY UOK AND DOK = HIGH-Z CHG = HIGH-Z FLT = HIGH-Z DONE = HIGH-Z ICHG = 0mA UOK OR DOK = LOW CEN = 0 RESET TIMER CEN = HIGH OR REMOVE AND RECONNECT THE INPUT SOURCE(S) ANY STATE
STATE DIAGRAM IS FOR 10NC < TEMP < +45NC, OUTSIDE OF THIS RANGE SEE FIGURE 6
TOGGLE CEN OR REMOVE AND RECONNECT THE INPUT SOURCE(S)
PREQUAL UOK OR DOK = LOW CHG = LOW FLT = HIGH-Z DONE = HIGH-Z 0V P VBATT P 3V ICHG = ICHGMAX 10 VBATT < 2.82V, RESET TIMER VBATT > 3V, RESET TIMER TIMER > tPQ
FAULT UOK AND DOK = LOW CHG = HIGH-Z FLT = LOW DONE = HIGH-Z ICHG = 0mA
FAST-CHARGE UOK OR DOK = LOW CHG = LOW FLT = HIGH-Z DONE = HIGH-Z 3V P VBATT P 4.2V ICHG = ICHGMAX ICHG < IDONE AND VBATT = 4.2V AND THERMAL OR OUTPUT LIMIT NOT EXCEEDED RESET TIMER TOP-OFF UOK OR DOK = LOW CHG = HIGH-Z FLT = HIGH-Z DONE = HIGH-Z BATT = 4.2V ICHG = IDONE
VBATT < 2.82V RESET TIMER
ICHG > IDONE RESET TIMER
TIMER > tFC (TIMER SLOWED BY 2X IF ICHG < ICHGMAX/2, AND PAUSED IF ICHG < ICHGMAX/5 WHILE BATT < 4.2V)
(PQ, FC, TOP-OFF) ANY CHARGING STATE VTHM_T1 < VTHM < VTHM_T4 TIMER RESUME VTHM_T1 < VTHM OR VTHM < VTHM_T4 TIMER SUSPEND
VBATT < 4.1V RESET TIMER
TEMPERATURE SUSPEND ICHG = 0mA UOK OR DOK = PREVIOUS STATE CHG = HIGH-Z FLT = HIGH-Z DONE = HIGH-Z VTHM > VTHM_OT OVERTEMP OT = LOW VTHM < VTHM_OT
TIMER > 15s
DONE UOK OR DOK = LOW CHG = HIGH-Z FLT = HIGH-Z DONE = LOW 4.1V < VBATT < 4.2V ICHG = 0mA
Figure 7. Charger State Diagram ______________________________________________________________________________________ 25
Dual-Input Linear Charger, Smart Power Selector with Advanced Battery Temperature Monitoring MAX8934G
Chip Information
PROCESS: BiCMOS
BATT BATT
Pin Configuration
THMSW 16 USB USB LDO
TOP VIEW
21 CHG 22 SYS 23 SYS 24 OT 25 DOK 26 UOK 27 FLT 28 1 DONE
20
19
18
17
THMEN 15 14 13 12 THM GND USUS ISET CT GND VL 11 10 9 8 7 PSET
MAX8934G
*EP
2 DC
3 DC
4 CEN
5 PEN1
6 PEN2
THIN QFN
*EXPOSED PAD
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Dual-Input Linear Charger, Smart Power Selector with Advanced Battery Temperature Monitoring
Package Information
For the latest package outline information and land patterns, go to www.maxim-ic.com/packages. Note that a "+", "#", or "-" in the package code indicates RoHS status only. Package drawings may show a different suffix character, but the drawing pertains to the package regardless of RoHS status. PACKAGE TYPE 28 TQFN-EP PACKAGE CODE T2844+1 OUTLINE NO. 21-0139 LAND PATTERN NO. 90-0068
MAX8934G
______________________________________________________________________________________
27
24L QFN THIN.EPS
Dual-Input Linear Charger, Smart Power Selector with Advanced Battery Temperature Monitoring MAX8934G
Package Information (continued)
For the latest package outline information and land patterns, go to www.maxim-ic.com/packages. Note that a "+", "#", or "-" in the package code indicates RoHS status only. Package drawings may show a different suffix character, but the drawing pertains to the package regardless of RoHS status.
28
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Dual-Input Linear Charger, Smart Power Selector with Advanced Battery Temperature Monitoring
Revision History
REVISION NUMBER 0 REVISION DATE 6/10 Initial release DESCRIPTION DATE PAGES CHANGED --
MAX8934G
Maxim cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim product. No circuit patent licenses are implied. Maxim reserves the right to change the circuitry and specifications without notice at any time.
Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600
(c)
29
2010 Maxim Integrated Products
Maxim is a registered trademark of Maxim Integrated Products, Inc.

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