View AAT2552IRN-CAE-T1_1205079.PDF datasheet online --- IC-ON-LINE

Datasheet File OCR Text:

AAT2552
Total Power Solution for Portable Applications General Description
The AAT2552 is a fully integrated 500mA battery charger, a 300mA step-down converter, and a 300mA low dropout (LDO) linear regulator. The input voltage range is 4V to 6.5V for the battery charger and 2.7V to 5.5V for the step-down converter and linear regulator, making it ideal for applications operating with single-cell lithium-ion/polymer batteries. The battery charger is a complete constant current/constant voltage linear charger. It offers an integrated pass device, reverse blocking protection, high accuracy current and voltage regulation, charge status, and charge termination. The charging current is programmable via external resistor from 30mA to 500mA. In addition to these standard features, the device offers over-voltage, current limit, and thermal protection. The step-down converter is a highly integrated converter operating at a 1.5MHz switching frequency, minimizing the size of external components while keeping switching losses low. The output voltage ranges from 0.6V to the input voltage. The AAT2552 linear regulator is designed for high speed turn-on and turn-off performance, fast transient response, and good power supply ripple rejection. Delivering up to 300mA of load current, it includes short-circuit protection and thermal shutdown. The AAT2552 is available in a Pb-free, thermallyenhanced TDFN34-16 package and is rated over the -40C to +85C temperature range.
Features
*
SystemPowerTM
*
*
* * *
Battery Charger: -- Input Voltage Range: 4V to 6.5V -- Programmable Charging Current up to 500mA -- Highly Integrated Battery Charger * Charging Device * Reverse Blocking Diode * Current Sensing Step-Down Converter: -- Input Voltage Range: 2.7V to 5.5V -- Output Voltage Range: 0.6V to VIN -- 300mA Output Current -- Up to 96% Efficiency -- 45A Quiescent Current -- 1.5MHz Switching Frequency -- 120s Start-Up Time Linear Regulator: -- 300mA Output Current -- Low Dropout: 400mV at 300mA -- Fast Line and Load Transient Response -- High Accuracy: 1.5% -- 85A Quiescent Current Short-Circuit, Over-Temperature, and Current Limit Protection TDFN34-16 Package -40C to +85C Temperature Range
Applications
* * * * * * * Bluetooth(R) Headsets Cellular Phones GPS Handheld Instruments MP3 and Portable Music Players PDAs and Handheld Computers Portable Media Players
Typical Application
Adapter/USB Input Enable
VOUTB RFBB1 COUTB 4.7F RFBB2 VOUTA RFBA1 COUTA RFBA2 FBA GND FBB OUTA L1 LX ADP STAT EN_BAT INB ENB INA ENA
AAT2552
MODE BAT ISET
System
BATT+
C OUT R SET Battery Pack
BATT-
2552.2007.04.1.0
1
AAT2552
Total Power Solution for Portable Applications Pin Descriptions
Pin #
1
Symbol
EN_BAT
Function
Enable pin for the battery charger. When connected to logic low, the battery charger is disabled and consumes less than 1A of current. When connected to logic high, the charger operates normally (pulled down internally). Charge current set point. Connect a resistor from this pin to ground. Refer to typical characteristics curves for resistor selection. Analog ground. Feedback input for the step-down converter. This pin must be connected directly to an external resistor divider. Nominal voltage is 0.6V. Enable pin for the step-down converter. When connected to logic low, the step-down converter is disabled and consumes less than 1A of current. When connected to logic high, the converter operates normally (pulled up internally). Pulled down internally for automatic PWM/LL operation. Connect to logic high for forced PWM. Drive with external clock signal to synchronize step-down converter to external clock in PWM mode. Enable pin for the linear regulator. When connected to logic low, the regulator is disabled and consumes less than 1A of current. When connected to logic high, the LDO operates normally (pulled up internally). Feedback input for the LDO. This pin must be connected directly to an external resistor divider. Nominal voltage is 1.24V. Linear regulator output. Connect a 2.2F capacitor from this pin to ground. Linear regulator input voltage. Connect a 1F or greater capacitor from this pin to ground. Input voltage for the step-down converter. Output of the step-down converter. Connect the inductor to this pin. Internally, it is connected to the drain of both high- and low-side MOSFETs. Power ground. Battery charging and sensing. Connect to positive terminal of Lithium-ion/polymer battery. Input from USB port or AC wall adapter. Open drain status pin for charger. Exposed paddle (bottom): connect to ground directly beneath the package.
2 3 4 5
ISET AGND FBB ENB
6
MODE
7
ENA
8 9 10 11 12 13 14 15 16 EP
FBA OUTA INA INB LX PGND BAT ADP STAT
Pin Configuration
TDFN34-16 (Top View)
EN_BAT ISET AGND FBB ENB MODE ENA FBA
1 2 3 4 5 6 7 8
16 15 14 13 12 11 10 9
STAT ADP BAT PGND LX INB INA OUTA
2
2552.2007.04.1.0
AAT2552
Total Power Solution for Portable Applications Absolute Maximum Ratings1
Symbol
VINA, VINB VADP VLX VFB VEN VX TJ TLEAD
Description
Input Voltage to GND Adapter Voltage to GND LX to GND FB to GND ENA, ENB, EN_BAT to GND BAT, ISET, STAT Operating Junction Temperature Range Maximum Soldering Temperature (at leads, 10 sec)
Value
6.0 -0.3 to 7.5 -0.3 to VIN + 0.3 -0.3 to VIN + 0.3 -0.3 to 6.0 -0.3 to VADP + 0.3 -40 to 150 300
Units
V V V V V V C C
Thermal Information
Symbol
PD JA
Description
Maximum Power Dissipation Thermal Resistance2
Value
2.0 50
Units
W C/W
1. Stresses above those listed in Absolute Maximum Ratings may cause permanent damage to the device. Functional operation at conditions other than the operating conditions specified is not implied. Only one Absolute Maximum Rating should be applied at any one time. 2. Mounted on an FR4 board. 2552.2007.04.1.0
3
AAT2552
Total Power Solution for Portable Applications Electrical Characteristics1
VINB = 3.6V; TA = -40C to +85C, unless otherwise noted. Typical values are TA = 25C. Symbol Description Conditions Min
2.7 VINB Rising Hysteresis IOUTB = 0 to 300mA, VINB = 2.7V to 5.5V No Load VENB = GND 300 0.3 0.5 VINB = 5.5V, VLX = 0 to VINB IOUTB = 0mA to 300mA VINB = 2.7V to 5.5V VINB = 3.6V VOUTB = 1.0V From Enable to Output Regulation 1.0 0.4 0.1 0.6 1.5 120 140 15 0.6 VINB = VENB = 5.5V 1.4 -1.0 1.0 250 -3.0 0.6 45 3.0 VINB 90 1.0
Typ
Max
5.5 2.6
Units
V V mV % V A A mA A % %/V V A MHz s C C V V A
Step-Down Converter VIN Input Voltage VUVLO VOUT VOUT IQ ISHDN ILIM RDS(ON)H RDS(ON)L ILXLEAK VOUT/VOUT VLinereg/VIN VFB IFB FOSC TS TSD THYS VEN(L) VEN(H) IEN UVLO Threshold Output Voltage Tolerance2 Output Voltage Range Quiescent Current Shutdown Current P-Channel Current Limit High-Side Switch On Resistance Low-Side Switch On Resistance LX Leakage Current Load Regulation Line Regulation Feedback Threshold Voltage Accuracy FB Leakage Current Oscillator Frequency Startup Time Over-Temperature Shutdown Threshold Over-Temperature Shutdown Hysteresis Enable Threshold Low Enable Threshold High Input Low Current
0.591
0.609 0.2
1. The AAT2552 is guaranteed to meet performance specifications over the -40C to +85C operating temperature range and is assured by design, characterization, and correlation with statistical process controls. 2. Output voltage tolerance is independent of feedback resistor network accuracy.
4
2552.2007.04.1.0
AAT2552
Total Power Solution for Portable Applications Electrical Characteristics1
VINA = VOUT(NOM) + 1V. IOUT = 1mA, COUT = 2.2F, TA = -40C to +85C, unless otherwise noted. Typical values are TA = 25C. Symbol Description Conditions
IOUTA = 1mA to 300mA TA = 25C TA = -40C to +85C
Min
Typ
Max
1.5 2.5 3.3 1.26 5.5 650 0.09
Units
Linear Regulator VOUT VOUT VFB VIN VDO VOUT/ VOUT*VIN IOUT ISC IQ ISHDN PSRR Output Voltage Tolerance Output Voltage Range Feedback Voltage Accuracy Input Voltage Dropout Voltage3 Line Regulation Output Current Short-Circuit Current Quiescent Current Shutdown Current Power Supply Rejection Ratio Over-Temperature Shutdown Threshold Over-Temperature Shutdown Hysteresis Output Noise Output Voltage Temperature Coefficient Enable Threshold Low Enable Threshold High Enable Input Current eNBW = 100Hz to 100kHz IOUTA = 300mA; VOUT = 3.3V VINA = VOUTA + 1 to 5.0V VOUTA > 2.0V VOUTA < 0.4V VINA = 5V; VENA = VIN VINA = 5V; VENA = 0V 1kHz IOUTA =10mA 10kHz 1MHz 300 400 85 70 50 30 140 15 95 8 0.6 1.4 VINA = VENA = 5.5V 1.0 150 1.0 -1.5 -2.5 1.2 1.22 1.24 VOUT + VDO2 400 % V V V mV %/V mA mA A A dB
TSD THYS eN TC VEN(L) VEN(H) IEN
C C VRMS/ Hz ppm/C V V A
1. The AAT2552 is guaranteed to meet performance specifications over the -40C to +85C operating temperature range and is assured by design, characterization, and correlation with statistical process controls. 2. VDO is defined as VIN - VOUT when VOUT is 98% of nominal. 3. For VOUT <2.3V, VDO = 2.5V - VOUT. 2552.2007.04.1.0
5
AAT2552
Total Power Solution for Portable Applications Electrical Characteristics1
VADP = 5V; TA = -40C to +85C, unless otherwise noted. Typical values are TA = 25C. Symbol Description Conditions Min Typ Max Units
Battery Charger Operation VADP Adapter Voltage Range Under-Voltage Lockout (UVLO) VUVLO UVLO Hysteresis IOP Operating Current ISHUTDOWN Shutdown Current ILEAKAGE Reverse Leakage Current from BAT Pin Voltage Regulation VBAT_EOC End of Charge Accuracy VMIN Preconditioning Voltage Threshold VRCH Battery Recharge Voltage Threshold Current Regulation ICH Charge Current Programmable Range ICH/ICH Charge Current Regulation Tolerance VSET ISET Pin Voltage KI_A Current Set Factor: ICH/ISET Charging Devices RDS(ON) Charging Transistor On Resistance Logic Control/Protection VEN(H) Enable Threshold High VEN(L) Enable Threshold Low VSTAT Output Low Voltage ISTAT STAT Pin Current Sink Capability VOVP Over-Voltage Protection Threshold ITK/ICHG Pre-Charge Current ITERM/ICHG Charge Termination Threshold Current
Rising Edge Charge Current = 200mA VBAT = 4.25V, VEN_BAT = GND VBAT = 4V, ADP Pin Open
4.0 3 150 0.5 0.3 0.4 4.158 2.8 4.20 3.0 -0.1
6.5 4 1 1 2 4.242 3.2
V V mV mA A A V V V mA % V
Measured from VBAT_EOC 30 -10
ICHARGE = 200mA
500 10 2 800
VADP = 5.5V 1.6 STAT Pin Sinks 4mA
0.5
0.8
V V V mA V % %
0.4 0.4 8 4.4 10 10
ICH = 100mA
1. The AAT2552 is guaranteed to meet performance specifications over the -40C to +85C operating temperature range and is assured by design, characterization, and correlation with statistical process controls.
6
2552.2007.04.1.0
AAT2552
Total Power Solution for Portable Applications Typical Characteristics-Battery Charger
Constant Charging Current vs. Set Resistors
(VIN = 5.0V)
10000 1000
Operating Supply Current vs. RSET
(VIN = 5.0V) Constant Current Mode
ICH (mA)
1000
IOP (A)
100
Preconditioning Mode
100
10 1 10 100 1000
10 1 10 100
RSET (k)
RSET (k)
Operating Current vs. Temperature
(VIN = 5.0V; RSET = 8.06k)
540
Sleep Mode Current vs. Input Voltage
(RSET = 8.06k)
800 700
520 600
85C
25C
ISLEEP (nA)
IOP (A)
500
500 400 300 200 100
480
460
-40C
4.5 5.0 5.5 6.0 6.5
440 -50 -25 0 25 50 75 100
0 4.0
Temperature (C)
Input Voltage (V)
Battery Charging Current vs. Battery Voltage
600
Constant Charging Current vs. Temperature
(RSET = 8.06k)
210
RSET = 3.24K
500 400
208 205
ICH (mA)
ICH (mA) RSET = 31.6K
3.5 3.7 3.9 4.1 4.3
RSET = 5.62K
300 200 100 0 2.7 2.9 3.1 3.3
203 200 198 195 193 190 -50 -25 0 25 50 75 100
RSET = 8.06K RSET = 16.2K
VBAT (V)
Temperature (C)
2552.2007.04.1.0
7
AAT2552
Total Power Solution for Portable Applications Typical Characteristics-Battery Charger
End of Charge Voltage Regulation vs. Temperature
(VIN = 5V; RSET = 8.06k)
4.206 4.204 4.210 4.215
End of Charge Battery Voltage vs. Input Voltage
RSET = 8.06k
VBAT_EOC (V)
VBAT_EOC (V)
4.202 4.200
4.205 4.200 4.195 4.190 4.185 -40 -15 10 35 60 85
RSET = 31.6k
4.198 4.196 4.194 4.5
5
5.5
6
6.5
Temperature (C)
VIN (V)
Recharging Threshold Voltage vs. Temperature
(RSET = 8.06k)
4.16 4.14 4.12
Constant Charging Current vs. Input Voltage
(VIN = 5.62V)
310
305
VIN = 3.3V VIN = 4V VIN = 3.6V
VRCH (V)
ICH (mA)
-15 10 35 60 85
300
4.10 4.08 4.06 4.04 -40
295
290
285 4 4.5 5 5.5 6 6.5
Temperature (C)
VIN (V)
Preconditioning Charge Current vs. Temperature
(RSET = 8.06k)
20.8
Preconditioning Voltage Threshold vs. Temperature
(RSET = 8.06k)
3.03 3.02
20.4
ITK (mA)
3.01
VMIN (V)
-15 10 35 60 85
20.0
3.00 2.99
19.6 2.98 19.2 -40 2.97 -40 -15 10 35 60 85
Temperature (C)
Temperature (C)
8
2552.2007.04.1.0
AAT2552
Total Power Solution for Portable Applications Typical Characteristics-Battery Charger
Enable Threshold High vs. Input Voltage
(RSET = 8.06k)
1.2 1.1 1.1
Enable Threshold Low vs. Input Voltage
(RSET = 8.06k)
-40C -40C VEN(L) (V) 85C
0.8 0.7 4.0 1.0 0.9 0.8 0.7 0.6 4.0
VEN(H) (V)
1.0 0.9
85C 25C
4.5 5.0 5.5 6.0 6.5
25C
4.5 5.0 5.5 6.0 6.5
VIN (V)
VIN (V)
2552.2007.04.1.0
9
AAT2552
Total Power Solution for Portable Applications Typical Characteristics-Step-Down Converter
Efficiency vs. Load
(VOUT = 3.3V; L = 5.6H)
100 1.0
DC Regulation
(VOUT = 3.3V; L = 5.6H)
VIN = 3.6V Output Error (%)
90
Efficiency (%)
80 70 60 50 40 0.1 1
VIN = 5.0V VIN = 4.2V
0.5
VIN = 5.0V
0.0
-0.5
VIN = 4.2V VIN = 3.6V
10
100
1000
-1.0 0.1
1
10
100
1000
Output Current (mA)
Output Current (mA)
Efficiency vs. Load
(VOUT = 1.8V; L = 3.3H)
100 1.0
DC Regulation
(VOUT = 1.8V; L = 3.3H)
VIN = 3.6V Output Error (%)
90
Efficiency (%)
VIN = 2.7V VIN = 5.0V VIN = 4.2V
0.5
80 70 60 50 40 0.1 1 10 100 1000
VIN = 3.6V
0.0
VIN = 2.7V
-0.5
VIN = 5.0V VIN = 4.2V
-1.0 0.1
1
10
100
1000
Output Current (mA)
Output Current (mA)
Efficiency vs. Load
(VOUT = 1.2V; L = 1.5H)
100 90 1.0
DC Regulation
(VOUT = 1.2V; L = 1.5H)
Output Error (%)
Efficiency (%)
VIN = 3.6V VIN = 2.7V VIN = 5.0V VIN = 4.2V
0.5
VIN = 3.6V
VIN = 5.0V
80 70 60 50 40 0.1
0.0
-0.5
VIN = 4.2V
VIN = 2.7V
1
10
100
1000
-1.0 0.1
1
10
100
1000
Output Current (mA)
Output Current (mA)
10
2552.2007.04.1.0
AAT2552
Total Power Solution for Portable Applications Typical Characteristics-Step-Down Converter
Line Regulation
(VOUT = 1.8V) Enable and Output Voltage (top) (V)
0.2 0.1 4 3 2 1 0
Soft Start
(VIN = 3.6V; VOUT = 1.8V; IOUT = 150mA) Inductor Current (bottom) (A) VEN VOUT
IOUT = 10mA IOUT = 50mA
Accuracy (%)
0 -0.1 -0.2 -0.3
IL
0.3 0.2 0.1 0.0
IOUT = 150mA
-0.4 2.7 3.1 3.5 3.9 4.3 4.7 5.1 5.5
Input Voltage (V)
Time (100s/div)
Output Voltage Accuracy vs. Temperature
(VIN = 3.6V; VO = 1.8V; IOUT = 150mA)
2.0
No Load Quiescent Current vs. Input Voltage
70
Output Accuracy (%)
1.5 1.0 60
85C
25C
0.0 -0.5 -1.0 -1.5 -2.0 -40
IQ (mA)
0.5
50
40
-40C
-15 10 35 60 85 30 2.7 3.1 3.5 3.9 4.3 4.7 5.1 5.5
Temperature (C)
Input Voltage (V)
N-Channel RDS(ON) vs. Input Voltage
1000 600
P-Channel RDS(ON) vs. Input Voltage
85C
900
120C
RDS(ON)H (m)
RDS(ON)L (m)
800 700 600 500 400 300 2.5
100C
500
85C
100C
120C
400
300
25C
3 3.5 4 4.5 5 5.5 6
200
25C
100 2.5
3
3.5
4
4.5
5
5.5
6
VIN (V)
VIN (V)
2552.2007.04.1.0
11
AAT2552
Total Power Solution for Portable Applications Typical Characteristics-Step-Down Converter
Load Transient Response
(10mA to 300mA; VIN = 3.6V; VOUT = 1.8V; COUT = 4.7F; C = 100pF)
2.0 1.90
Line Transient Response
(VOUT = 1.8V @ 150mA, CFF = 100pF) Input Voltage (bottom) (V) Output Voltage (top) (V)
1.85 1.80 1.75
Load and Inductor Current (bottom) (A)
Output Voltage (top) (V)
1.9 1.8 1.7 1.6 IOUT
VOUT
300mA
10mA 0.2 0.0 -0.2
4.6 4.1 3.6 3.1
ILX
Time (20s/div)
Time (25s/div)
Output Voltage Ripple
(VIN = 3.6V; VOUT = 1.8V; IOUT = 300mA) Inductor Current (bottom) (A) Output Voltage (AC coupled) (top) (V) Output Voltage (AC coupled) (top) (V)
40 20 0 -20 1.81 1.80 1.79
Output Voltage Ripple
(VIN = 3.6V; VOUT = 1.8V; IOUT = 1mA) Inductor Current (bottom) (A)
0.4 0.3 0.2 0.1
0.05 0.00 -0.05 -0.10
Time (0.2s/div)
Time (5s/div)
12
2552.2007.04.1.0
AAT2552
Total Power Solution for Portable Applications Typical Characteristics-LDO Regulator
Quiescent Current vs. Temperature
(VIN = 5V)
120 0.5
Dropout Voltage vs. Temperature
Dropout Voltage (V)
110 100
IL = 300mA
0.4 0.3 0.2 0.1 0.0 -40
IQ (A)
90 80 70 60 50 -40 -15 10 35 60 85
IL = 200mA IL = 100mA IL = 50mA
-20 0 20 40 60 80 100 120
Temperature (C)
Temperature (C)
Dropout Characteristics
3.8 0.5 3.6
Dropout Voltage vs. Output Current
85C Dropout Voltage (V)
0.4 0.3 0.2 0.1 0.0
IOUT = 0mA IOUT = 50mA 25C
Output Voltage (V)
3.4 3.2 3 2.8 2.6 2.4 3 3.2 3.4 3.6 3.8 4
IOUT = 300mA IOUT = 100mA
-40C
0
50
100
150
200
250
300
Input Voltage (V)
Output Current (mA)
Output Voltage vs. Temperature
(VIN = 3.6V; VO = 1.8V; IOUT = 150mA)
3.301
Enable Threshold Voltage vs. Input Voltage
0.96 0.94
Output Voltage (V)
3.300 3.299 3.298 3.297
VENABLE (V)
0.92 0.9 0.88 0.86
VEN(H)
VEN(L)
0.84 0.82 2.7
3.296 -40 -15 10 35 60 85
3.1
3.5
3.9
4.3
4.7
5.1
5.5
Temperature (C)
Input Voltage (V)
2552.2007.04.1.0
13
AAT2552
Total Power Solution for Portable Applications Typical Characteristics-LDO Regulator
Line Transient Response
(IOUT = 300mA)
3.40 3.6
Load Transient Response
(1mA to 300mA; VIN = 5.0V; VOUT = 3.3V) Output Current (bottom) (A) Input Voltage (bottom) (V) Output Voltage (top) (V)
3.4 3.2
Output Voltage (top) (V)
3.35 3.30
VOUT
VOUT
5.0
VIN
4.5 4.0
0.4
IL
0.2 0.0 -0.2
Time (100s/div)
Time (100s/div)
Turn-Off Response Time
(VIN = 4.2V; IOUT = 300mA) Enable and Output Voltage Enable and Output Voltage
Turn-On Time From Enable
(VIN = 4.2V; IOUT = 300mA)
VEN = 2V/div
VEN = 2V/div
VOUT = 1V/div
VOUT = 1V/div
Time (50s/div)
Time (100s/div)
LDO Output Noise
(COUT = 4.7F; IOUT = 10mA; RLOAD = 330; 98.33Vrms)
10000
nVrms/sqrt (Hz)
1000
100
10 0.01 0.1 1 10 100 1000
Frequency (kHz)
14
2552.2007.04.1.0
AAT2552
Total Power Solution for Portable Applications Functional Block Diagram
Reverse Blocking
ADP
Current Compare CV/Pre-Charge
BAT
ISET
Constant Current
Charge Control
UVLO
STAT
Charge Status
FBB INB
EN_BAT
Err. Amp
. DH
Voltage Reference
Logic
LX
ENB MODE
Input
DL
From Charger Section
Over-Temperature Protection
PGND
INA
Active Feedback Control
+
OUTA
Over-Current Protection
ENA
Fast Start Control
Err. Amp
FBA
Voltage Reference
-
AGND
Functional Description
The AAT2552 is a high performance power management IC comprised of a lithium-ion/polymer battery charger, a step-down converter, and a linear regulator. The linear regulator is designed for high-speed turn-on and fast transient response, and good power supply ripple rejection. The stepdown converter operates in both fixed and variable frequency modes for high efficiency performance. The switching frequency is 1.5MHz, minimizing the size of the inductor. In light load conditions, the device enters power-saving mode; the switching frequency is reduced and the converter consumes 45A of current, making it ideal for batteryoperated applications.
Battery Charger
The battery charger is designed for single-cell lithium-ion/polymer batteries using a constant current and constant voltage algorithm. The battery charger operates from the adapter/USB input voltage range from 4V to 6.5V. The adapter/USB charging current level can be programmed up to 500mA for rapid charging applications. A status monitor output pin is provided to indicate the battery charge state by directly driving one external LED. Internal device temperature and charging state are fully monitored for fault conditions. In the event of an over-voltage or over-temperature failure, the device will automatically shut down, protecting the charging device, control system, and the battery under charge. Other features include an integrated reverse blocking diode and sense resistor. 15
2552.2007.04.1.0
AAT2552
Total Power Solution for Portable Applications
Switch-Mode Step-Down Converter
The step-down converter operates with an input voltage of 2.7V to 5.5V. The switching frequency is 1.5MHz, minimizing the size of the inductor. Under light load conditions, the device enters power-saving mode; the switching frequency is reduced, and the converter consumes 45A of current, making it ideal for battery-operated applications. The output voltage is programmable from VIN to as low as 0.6V. Power devices are sized for 300mA current capability while maintaining over 96% efficiency at full load. Light load efficiency is maintained at greater than 80% down to 1mA of load current. A high-DC gain error amplifier with internal compensation controls the output. It provides excellent transient response and load/line regulation. The AAT2552 synchronous step-down converter can be synchronized to an external clock signal applied to the MODE pin.
Under-Voltage Lockout
The AAT2552 has internal circuits for UVLO and power on reset features. If the ADP supply voltage drops below the UVLO threshold, the battery charger will suspend charging and shut down. When power is reapplied to the ADP pin or the UVLO condition recovers, the system charge control will automatically resume charging in the appropriate mode for the condition of the battery. If the input voltage of the step-down converter drops below UVLO, the internal circuit will shut down.
Protection Circuitry
Over-Voltage Protection An over-voltage protection event is defined as a condition where the voltage on the BAT pin exceeds the over-voltage protection threshold (VOVP). If this over-voltage condition occurs, the charger control circuitry will shut down the device. The charger will resume normal charging operation after the over-voltage condition is removed. Current Limit, Over-Temperature Protection For overload conditions, the peak input current is limited at the step-down converter. As load impedance decreases and the output voltage falls closer to zero, more power is dissipated internally, which causes the internal die temperature to rise. In this case, the thermal protection circuit completely disables switching, which protects the device from damage. The battery charger has a thermal protection circuit which will shut down charging functions when the internal die temperature exceeds the preset thermal limit threshold. Once the internal die temperature falls below the thermal limit, normal charging operation will resume.
Linear Regulator
The advanced circuit design of the linear regulator has been specifically optimized for very fast startup. This proprietary CMOS LDO has also been tailored for superior transient response characteristics. These traits are particularly important for applications that require fast power supply timing. The high-speed turn-on capability is enabled through implementation of a fast-start control circuit which accelerates the power-up behavior of fundamental control and feedback circuits within the LDO regulator. The LDO regulator output has been specifically optimized to function with lowcost, low-ESR ceramic capacitors; however, the design will allow for operation over a wide range of capacitor types. The regulator comes with complete short-circuit and thermal protection. The combination of these two internal protection circuits gives a comprehensive safety system to guard against extreme adverse operating conditions. The regulator features an enable/disable function. This pin (ENA) is active high and is compatible with CMOS logic. The LDO regulator will go into the disable shutdown mode when the voltage on the ENA pin falls below 0.6V. If the enable function is not needed in a specific application, it may be tied to INA to keep the LDO regulator in a continuously on state. 16
Control Loop
The AAT2552 contains a compact, current mode step-down DC/DC controller. The current through the P-channel MOSFET (high side) is sensed for current loop control, as well as short-circuit and overload protection. A fixed slope compensation signal is added to the sensed current to maintain stability for duty cycles greater than 50%. The peak current mode loop appears as a voltage-programmed current source in parallel with the output capacitor. The output of the voltage error amplifier programs the current mode loop for the necessary
2552.2007.04.1.0
AAT2552
Total Power Solution for Portable Applications
peak switch current to force a constant output voltage for all load and line conditions. Internal loop compensation terminates the transconductance voltage error amplifier output. The error amplifier reference is fixed at 0.6V. rent level for this mode is programmed using a single resistor from the ISET pin to ground. Programmed current can be set from a minimum 15mA up to a maximum of 500mA. Constant current charging will continue until the battery voltage reaches the voltage regulation point, VBAT. When the battery voltage reaches VBAT, the battery charger begins constant voltage mode. The regulation voltage is factory programmed to a nominal 4.2V (0.5%) and will continue charging until the charging current has reduced to 10% of the programmed current. After the charge cycle is complete, the pass device turns off and the device automatically goes into a power-saving sleep mode. During this time, the series pass device will block current in both directions, preventing the battery from discharging through the IC. The battery charger will remain in sleep mode, even if the charger source is disconnected, until one of the following events occurs: the battery terminal voltage drops below the VRCH threshold; the charger EN pin is recycled; or the charging source is reconnected. In all cases, the charger will monitor all parameters and resume charging in the most appropriate mode.
Battery Charging Operation
Battery charging commences only after checking several conditions in order to maintain a safe charging environment. The input supply (ADP) must be above the minimum operating voltage (UVLO) and the enable pin must be high (internally pulled down). When the battery is connected to the BAT pin, the charger checks the condition of the battery and determines which charging mode to apply. If the battery voltage is below VMIN, the charger begins battery pre-conditioning by charging at 10% of the programmed constant current; e.g., if the programmed current is 150mA, then the pre-conditioning current (trickle charge) is 15mA. Pre-conditioning is purely a safety precaution for a deeply discharged cell and will also reduce the power dissipation in the internal series pass MOSFET when the input-output voltage differential is at its highest. Pre-conditioning continues until the battery voltage reaches VMIN (see Figure 1). At this point, the charger begins constant-current charging. The cur-
Preconditioning Trickle Charge Phase Charge Complete Voltage Regulated Current
Constant Current Charge Phase I = Max CC
Constant Voltage Charge Phase
Constant Current Mode Voltage Threshold
Trickle Charge and Termination Threshold
I = CC / 10
Figure 1: Current vs. Voltage Profile During Charging Phases.
2552.2007.04.1.0
17
AAT2552
Total Power Solution for Portable Applications
Battery Charging System Operation Flow Chart
Enable
Power On Reset
No
Yes
Power Input Voltage VADP > VUVLO
Yes
Shut Down
Yes
Fault Conditions Monitoring OV, OT
Charge Control
No
Preconditioning Test V MIN > VBAT
Yes
Preconditioning (Trickle Charge)
No No Recharge Test V RCH > VBAT Yes Current Phase Test V BAT_EOC > VBAT Yes Constant Current Charge Mode
No
Voltage Phase Test IBAT > ITERM
Yes
Constant Voltage Charge Mode
No
Charge Completed
18
2552.2007.04.1.0
AAT2552
Total Power Solution for Portable Applications Application Information
Soft Start / Enable
The EN_BAT pin is internally pulled down. When pulled to a logic high level, the battery charger is enabled. When left open or pulled to a logic low level, the battery charger is shut down and forced into the sleep state. Charging will be halted regardless of the battery voltage or charging state. When it is reenabled, the charge control circuit will automatically reset and resume charging functions with the appropriate charging mode based on the battery charge state and measured cell voltage from the BAT pin. Separate ENA and ENB inputs are provided to independently enable and disable the LDO and step-down converter, respectively. This allows sequencing of the LDO and step-down outputs during startup. The LDO is enabled when the ENA pin is pulled high. The control and feedback circuits have been optimized for high-speed, monotonic turn-on characteristics. The step-down converter is enabled when the ENB pin is pulled high. Soft start increases the inductor current limit point in discrete steps when the input voltage or ENB input is applied. It limits the current surge seen at the input and eliminates output voltage overshoot. When pulled low, the ENB input forces the AAT2552 into a low-power, non-switching state. The step-down converter input current during shutdown is less than 1A. the fast charge, as well as the preconditioning trickle charge current, is dominated by the tolerance of the set resistor used. For this reason, a 1% tolerance metal film resistor is recommended for the set resistor function. Fast charge constant current levels from 30mA to 500mA may be set by selecting the appropriate resistor value from Table 1. Normal ICHARGE (mA)
500 400 300 250 200 150 100 50 40 30 20 15
Set Resistor Value R1 (k)
3.24 4.12 5.36 6.49 8.06 10.7 16.2 31.6 38.3 53.6 78.7 105
Table 1: RSET Values.
1000
ICH (mA)
100
10
Adapter or USB Power Input
Constant current charge levels up to 500mA may be programmed by the user when powered from a sufficient input power source. The battery charger will operate from the adapter input over a 4.0V to 6.5V range. The constant current fast charge current for the adapter input is set by the RSET resistor connected between ISET and ground. Refer to Table 1 for recommended RSET values for a desired constant current charge level.
1 1 10 100 1000
RSET (k)
Figure 2: Constant Charging Current vs. Set Resistor Values.
Charge Status Output
The AAT2552 provides battery charge status via a status pin. This pin is internally connected to an Nchannel open drain MOSFET, which can be used to drive an external LED. The status pin can indicate several conditions, as shown in Table 2.
Programming Charge Current
The fast charge constant current charge level is user programmed with a set resistor placed between the ISET pin and ground. The accuracy of
2552.2007.04.1.0
19
AAT2552
Total Power Solution for Portable Applications
First, the maximum power dissipation for a given situation should be calculated:
Event Description
No battery charging activity Battery charging via adapter or USB port Charging completed
Status
OFF ON OFF
PD(MAX) =
Where:
(TJ(MAX) - TA) JA
Table 2: LED Status Indicator. The LED should be biased with as little current as necessary to create reasonable illumination; therefore, a ballast resistor should be placed between the LED cathode and the STAT pin. LED current consumption will add to the overall thermal power budget for the device package, hence it is good to keep the LED drive current to a minimum. 2mA should be sufficient to drive most low-cost green or red LEDs. It is not recommended to exceed 8mA for driving an individual status LED. The required ballast resistor values can be estimated using the following formulas:
PD(MAX) = Maximum Power Dissipation (W) JA = Package Thermal Resistance (C/W) TJ(MAX) = Maximum Device Junction Temperature (C) [135C] TA = Ambient Temperature (C)
Figure 3 shows the relationship of maximum power dissipation and ambient temperature of the AAT2552.
3.00 2.50
PD(MAX) (mW)
2.00 1.50 1.00 0.50 0.00 0 20 40 60 80 100
(VADP - VF(LED)) R6 = ILED
Example:
R6 =
(5.5V - 2.0V) = 1.75k 2mA
TA (C)
Figure 3: Maximum Power Dissipation. Next, the power dissipation of the battery charger can be calculated by the following equation: PD = [(VADP - VBAT) * ICH + (VADP * IOP)] Where: PD = Total Power Dissipation by the Device
Note: Red LED forward voltage (VF) is typically 2.0V @ 2mA.
Thermal Considerations
The AAT2552 is offered in a TDFN34-16 package which can provide up to 2W of power dissipation when it is properly bonded to a printed circuit board and has a maximum thermal resistance of 50C/W. Many considerations should be taken into account when designing the printed circuit board layout, as well as the placement of the charger IC package in proximity to other heat generating devices in a given application design. The ambient temperature around the IC will also have an effect on the thermal limits of a battery charging application. The maximum limits that can be expected for a given ambient condition can be estimated by the following discussion.
VADP = ADP/USB Voltage VBAT = Battery Voltage as Seen at the BAT Pin ICH IOP = Constant Charge Current Programmed for the Application = Quiescent Current Consumed by the Charger IC for Normal Operation [0.5mA]
20
2552.2007.04.1.0
AAT2552
Total Power Solution for Portable Applications
By substitution, we can derive the maximum charge current before reaching the thermal limit condition (thermal cycling). The maximum charge current is the key factor when designing battery charger applications. IQ is the step-down converter quiescent current. The term tsw is used to estimate the full load stepdown converter switching losses. For the condition where the step-down converter is in dropout at 100% duty cycle, the total device dissipation reduces to:
PTOTAL = IO2 * RDSON(H) + IQ * VIN
ICH(MAX) =
(PD(MAX) - VIN * IOP) VIN - VBAT
(TJ(MAX) - TA) - V * I IN OP JA ICH(MAX) = VIN - VBAT
In general, the worst condition is the greatest voltage drop across the IC, when battery voltage is charged up to the preconditioning voltage threshold. Figure 4 shows the maximum charge current in different ambient temperatures.
500 450 400
Since RDS(ON), quiescent current, and switching losses all vary with input voltage, the total losses should be investigated over the complete input voltage range. Given the total losses, the maximum junction temperature can be derived from the JA for the TDFN34-16 package which is 50C/W.
TJ(MAX) = PTOTAL * JA + TAMB
TA = 60C TA = 45C TA = 85C
ICH(MAX) (mA)
350 300 250 200 150 100 50 0 4.25 4.5 4.75 5 5.25 5.5 5.75 6
Capacitor Selection
Linear Regulator Input Capacitor (C6) An input capacitor greater than 1F will offer superior input line transient response and maximize power supply ripple rejection. Ceramic, tantalum, or aluminum electrolytic capacitors may be selected for CIN. There is no specific capacitor ESR requirement for CIN. However, for 300mA LDO regulator output operation, ceramic capacitors are recommended for CIN due to their inherent capability over tantalum capacitors to withstand input current surges from low impedance sources such as batteries in portable devices. Battery Charger Input Capacitor (C1) In general, it is good design practice to place a decoupling capacitor between the ADP pin and GND. An input capacitor in the range of 1F to 22F is recommended. If the source supply is unregulated, it may be necessary to increase the capacitance to keep the input voltage above the under-voltage lockout threshold during device enable and when battery charging is initiated. If the adapter input is to be used in a system with an external power supply source, such as a typical AC-to-DC wall adapter, then a CIN capacitor in the range of 10F should be used. A larger input
6.25
6.5
6.75
VIN (V)
Figure 4: Maximum Charging Current Before Thermal Cycling Becomes Active. There are three types of losses associated with the step-down converter: switching losses, conduction losses, and quiescent current losses. Conduction losses are associated with the RDS(ON) characteristics of the power output switching devices. Switching losses are dominated by the gate charge of the power output switching devices. At full load, assuming continuous conduction mode (CCM), a simplified form of the losses is given by:
IO2 * (RDSON(H) * VO + RDSON(L) * [VIN - VO]) VIN
PTOTAL =
+ (tsw * FS * IO + IQ) * VIN
2552.2007.04.1.0
21
AAT2552
Total Power Solution for Portable Applications
capacitor in this application will minimize switching or power transient effects when the power supply is "hot plugged" in. Step-Down Converter Input Capacitor (C6) Select a 4.7F to 10F X7R or X5R ceramic capacitor for the input. To estimate the required input capacitor size, determine the acceptable input ripple level (VPP) and solve for CIN. The calculated value varies with input voltage and is a maximum when VIN is double the output voltage. V VO * 1- O VIN VIN
VPP - ESR * FS IO
VO
IRMS(MAX) =
V * 1- O
IO 2
The term VIN VIN appears in both the input voltage ripple and input capacitor RMS current equations and is a maximum when VO is twice VIN. This is why the input voltage ripple and the input capacitor RMS current ripple are a maximum at 50% duty cycle. The input capacitor provides a low impedance loop for the edges of pulsed current drawn by the stepdown converter. Low ESR/ESL X7R and X5R ceramic capacitors are ideal for this function. To minimize stray inductance, the capacitor should be placed as closely as possible to the IC. This keeps the high frequency content of the input current localized, minimizing EMI and input voltage ripple. The proper placement of the input capacitor (C6) can be seen in the evaluation board layout in Figure 7. A laboratory test set-up typically consists of two long wires running from the bench power supply to the evaluation board input voltage pins. The inductance of these wires, along with the low-ESR ceramic input capacitor, can create a high Q network that may affect converter performance. This problem often becomes apparent in the form of excessive ringing in the output voltage during load transients. Errors in the loop phase and gain measurements can also result. Since the inductance of a short PCB trace feeding the input voltage is significantly lower than the power leads from the bench power supply, most applications do not exhibit this problem. In applications where the input power source lead inductance cannot be reduced to a level that does not affect the converter performance, a high ESR tantalum or aluminum electrolytic capacitor should be placed in parallel with the low ESR, ESL bypass ceramic capacitor. This dampens the high Q network and stabilizes the system. The linear regulator and the step-down convertor share the same input capacitor on the evaluation board.
CIN =
VO V 1 * 1 - O = for VIN = 2 * VO VIN VIN 4 CIN(MIN) = 1 VPP - ESR * 4 * FS IO
Always examine the ceramic capacitor DC voltage coefficient characteristics when selecting the proper value. For example, the capacitance of a 10F, 6.3V, X5R ceramic capacitor with 5.0V DC applied is actually about 6F. The maximum input capacitor RMS current is: VO V * 1- O VIN VIN
IRMS = IO *
The input capacitor RMS ripple current varies with the input and output voltage and will always be less than or equal to half of the total DC load current. VO V * 1- O = VIN VIN for VIN = 2 * VO 1 2
D * (1 - D) =
0.52 =
22
2552.2007.04.1.0
AAT2552
Total Power Solution for Portable Applications
Linear Regulator Output Capacitor (C5) For proper load voltage regulation and operational stability, a capacitor is required between OUT and GND. The COUT capacitor connection to the LDO regulator ground pin should be made as directly as practically possible for maximum device performance. Since the regulator has been designed to function with very low ESR capacitors, ceramic capacitors in the 1.0F to 10F range are recommended for best performance. Applications utilizing the exceptionally low output noise and optimum power supply ripple rejection should use 2.2F or greater for COUT. In low output current applications, where output load is less than 10mA, the minimum value for COUT can be as low as 0.47F. Battery Charger Output Capacitor (C2) The battery charger of the AAT2552 only requires a 1F ceramic capacitor on the BAT pin to maintain circuit stability. This value should be increased to 10F or more if the battery connection is made any distance from the charger output. If the AAT2552 is to be used in applications where the battery can be removed from the charger, such as with desktop charging cradles, an output capacitor greater than 10F may be required to prevent the device from cycling on and off when no battery is present. Step-Down Converter Output Capacitor (C3) The output capacitor limits the output ripple and provides holdup during large load transitions. A 4.7F to 10F X5R or X7R ceramic capacitor typically provides sufficient bulk capacitance to stabilize the output during large load transitions and has the ESR and ESL characteristics necessary for low output ripple. For enhanced transient response and low temperature operation applications, a 10F (X5R, X7R) ceramic capacitor is recommended to stabilize extreme pulsed load conditions. The output voltage droop due to a load transient is dominated by the capacitance of the ceramic output capacitor. During a step increase in load current, the ceramic output capacitor alone supplies the load current until the loop responds. Within two or three switching cycles, the loop responds and the inductor current increases to match the load current demand. The relationship of the output voltage droop during the three switching cycles to the output capacitance can be estimated by: 3 * ILOAD VDROOP * FS
COUT =
Once the average inductor current increases to the DC load level, the output voltage recovers. The above equation establishes a limit on the minimum value for the output capacitor with respect to load transients. The internal voltage loop compensation also limits the minimum output capacitor value to 4.7F. This is due to its effect on the loop crossover frequency (bandwidth), phase margin, and gain margin. Increased output capacitance will reduce the crossover frequency with greater phase margin. The maximum output capacitor RMS ripple current is given by:
VOUT * (VIN(MAX) - VOUT) L * FS * VIN(MAX) 2* 3 * 1
IRMS(MAX) =
Dissipation due to the RMS current in the ceramic output capacitor ESR is typically minimal, resulting in less than a few degrees rise in hotspot temperature.
Inductor Selection
The step-down converter uses peak current mode control with slope compensation to maintain stability for duty cycles greater than 50%. The output inductor value must be selected so the inductor current down slope meets the internal slope compensation requirements. The internal slope compensation for the AAT2552 is 0.45A/sec. This equates to a slope compensation that is 75% of the inductor current down slope for a 1.8V output and 3.0H inductor.
2552.2007.04.1.0
23
AAT2552
Total Power Solution for Portable Applications
0.75 VO 0.75 1.8V A = = 0.45 L 3.0H sec sec 0.75 VO 1.67 A VO A 0.45A sec
R3 = 59k VOUT (V)
0.8 0.9 1.0 1.1 1.2 1.3 1.4 1.5 1.8 1.85 2.0 2.5 3.3
m=
R3 = 221k R2 (k)
75 113 150 187 221 261 301 332 442 464 523 715 1000
R2 (k)
19.6 29.4 39.2 49.9 59.0 68.1 78.7 88.7 118 124 137 187 267
0.75 VO L= = m
For most designs, the step-down converter operates with inductor values from 1H to 4.7H. Table 6 displays inductor values for the AAT2552 for various output voltages. Manufacturer's specifications list both the inductor DC current rating, which is a thermal limitation, and the peak current rating, which is determined by the saturation characteristics. The inductor should not show any appreciable saturation under normal load conditions. Some inductors may meet the peak and average current ratings yet result in excessive losses due to a high DCR. Always consider the losses associated with the DCR and its effect on the total converter efficiency when selecting an inductor. The 3.0H CDRH2D09 series inductor selected from Sumida has a 150m DCR and a 470mA DC current rating. At full load, the inductor DC loss is 9.375mW which gives a 2.08% loss in efficiency for a 250mA, 1.8V output.
Table 3: Adjustable Resistor Values For Step-Down Converter.
Adjustable Output Voltage for the LDO
The output voltage for the LDO can be programmed by an external resistor divider network. As shown below, the selection of R4 and R5 is a straightforward matter. R5 is chosen by considering the tradeoff between the feedback network bias current and resistor value. Higher resistor values allow stray capacitance to become a larger factor in circuit performance whereas lower resistor values increase bias current and decrease efficiency. To select appropriate resistor values, first choose R5 such that the feedback network bias current is reasonable. Then, according to the desired VOUT, calculate R4 according to the equation below. An example calculation follows.
VOUT - 1 * R5 VREF
Adjustable Output Voltage for the Stepdown Converter
Resistors R2 and R3 of Figure 5 program the output of the step down converter and regulate at a voltage higher than 0.6V. To limit the bias current required for the external feedback resistor string while maintaining good noise immunity, the suggested value for R3 is 59k. Decreased resistor values are necessary to maintain noise immunity on the FBB pin, resulting in increased quiescent current. Table 3 summarizes the resistor values for various output voltages.
VOUT 3.3V R2 = V -1 * R3 = 0.6V - 1 * 59k = 267k REF
R4 =
With enhanced transient response for extreme pulsed load application, an external feed-forward capacitor (C8 in Figure 5) can be added. 24
An R5 value of 59k is chosen, resulting in a small feedback network bias current of 1.24V/59k 21A. The desired output voltage is 1.8V. From this information, R4 is calculated from the equation below. The result is R4 = 26.64k. Since 26.64k is not a standard 1%-value, 26.7k is selected. From this example calculation, for VOUT = 1.8V, use R5 = 59k and R4 = 26.7k. Example output voltages and corresponding resistor values are provided in Table 4.
2552.2007.04.1.0
AAT2552
Total Power Solution for Portable Applications
R4 Standard 1% Values VOUT (V)
3.3 2.8 2.5 2.0 1.8 1.5
(R5 = 59k) R4 (k)
97.6 75.0 60.4 36.5 26.7 12.4
Table 4: Adjustable Resistor Values for the LDO.
Printed Circuit Board Layout Considerations
For the best results, it is recommended to physically place the battery pack as close as possible to the AAT2552 BAT pin. To minimize voltage drops on the PCB, keep the high current carrying traces adequately wide. Refer to the AAT2552 evaluation board for a good layout example (see Figures 6 and 7). The following guidelines should be used to help ensure a proper layout.
1. The input capacitors (C1, C6) should connect as closely as possible to ADP, INA, and INB. It is possible to use two input capacitors for INA and INB. 2. C4 and L1 should be connected as closely as possible. The connection of L1 to the LX pin should be as short as possible. Do not make the node small by using narrow trace. The trace should be kept wide, direct, and short. 3. The feedback pin should be separate from any power trace and connect as closely as possible to the load point. Sensing along a high-current load trace will degrade DC load regulation. Feedback resistors should be placed as closely as possible to the FBB pin to minimize the length of the high impedance feedback trace. If possible, they should also be placed away from the LX (switching node) and inductor to improve noise immunity. 4. The resistance of the trace from PGND should be kept to a minimum. This will help to minimize any error in DC regulation due to differences in the potential of the internal signal ground and the power ground. 5. A high density, small footprint layout can be achieved using an inexpensive, miniature, nonshielded, high DCR inductor.
2552.2007.04.1.0
25
AAT2552
Total Power Solution for Portable Applications
JP1
21
EN_BAT ADP
321
Power Selection
BAT
D1 RED LED Sync/Mode R6 1.5K
C1 10F U1
15 16 1 6
C6 10F (at bottom layer)
10 11 7 5 14 2
JP2
1 2
EN_LDO JP3
1 2
VoB C4 100pF R2 (Optional) C3 4.7F
ADP STAT EN_BAT MODE LX FBB AGND PGND
INA INB ENA ENB BAT ISET OUTA FBA
EN_BUCK
L1
12 4 3 13
VoA
9 8
C2 10F R1 8.06K C5 4.7F
R4
R3 59k R5 59k
VOUTB (V) R2 () 0.6 13 1.2 1.8 2.5 3.0 3.3 R2 short, R3 open 9.2K 59K 118K 187K 237K 267K
L1 1.5H (CDRH2D09/HP; DCR 88m; 730mA @ 20C) 2.2H (CDRH2D09/HP; DCR 115m; 600mA @ 20C) 3.0H (CDRH2D09/HP; DCR 150m; 470mA @ 20C) 3.9H (CDRH2D09/HP; DCR 180m; 450mA @ 20C) 4.7H (CDRH2D09/HP; DCR 230m; 410mA @ 20C) 5.6H (CDRH2D09/HP; DCR 260m; 370mA @ 20C)
VOUTA (V) 1.24 1.5 1.8 2.0 2.5 2.8 3.0
R4 () R4 short, R5 open 12.4K 26.7K 36.5K 60.4K 75.0K 97.6K
Figure 5: AAT2552 Evaluation Board Schematic.
Figure 6: AAT2552 Evaluation Board Top Side Layout.
Figure 7: AAT2552 Evaluation Board Bottom Side Layout.
26
2552.2007.04.1.0
AAT2552
Total Power Solution for Portable Applications
Component
U1 C1, C2 C3, C5 C6 C4 L1 R6 R1 R2 R3, R5 R4 JP1, JP2, JP3, JP4 D1
Part Number
AAT2552IRN ECJ-1VB0J106M GRM188R60J475KE19 GRM319R61A106KE19 GRM1886R1H101JZ01J CDRH2D09 Chip Resistor Chip Resistor Chip Resistor Chip Resistor Chip Resistor PRPN401PAEN CMD15-21SRC/TR8
Description
Total Power Solution for Portable Applications CER 10F 6.3V X5R 0603 CER 4.7F 6.3V X5R 0603 CER 10F 10V X5R 1206 CER 100pF 50V 5% R2H 0603 Shielded SMD, 3x3x1mm 1.5K, 5%, 1/4W 0603 8.06K, 1%, 1/4W 0603 118K, 1%, 1/4W 0603 59K, 1%, 1/4W 0603 60.4K, 1%, 1/4W 0603 Conn. Header, 2mm zip Red LED 1206
Manufacturer
AnalogicTech Panansonic Murata Murata Murata Sumida Vishay Vishay Vishay Vishay Vishay Sullins Electronics Chicago Miniature Lamp
Table 5: AAT2552 Evaluation Board Component Listing.
2552.2007.04.1.0
27
AAT2552
Total Power Solution for Portable Applications Step-Down Converter Design Example (to be updated)
Specifications
VO VIN FS TAMB = 1.8V @ 250mA, Pulsed Load ILOAD = 200mA = 2.7V to 4.2V (3.6V nominal) = 1.5MHz = 85C
1.8V Output Inductor
L1 = 1.67 sec sec VO2 = 1.67 1.8V = 3H A A
(use 3.0H; see Table 3)
For Sumida inductor CDRH2D09-3R0, 3.0H, DCR = 150m. VO V 1.8V 1.8V 1- O = 1 = 228mA L1 FS VIN 3.0H 1.5MHz 4.2V
IL1 =
IPKL1 = IO +
IL1 = 250mA + 114mA = 364mA 2
PL1 = IO2 DCR = 250mA2 150m = 9.375mW
1.8V Output Capacitor
VDROOP = 0.1V
3 * ILOAD 3 * 0.2A = = 4F (use 4.7F) VDROOP * FS 0.1V * 1.5MHz 1 2* 3 * (VO) * (VIN(MAX) - VO) 1 1.8V * (4.2V - 1.8V) * = 66mArms = L1 * FS * VIN(MAX) 2 * 3 3.0H * 1.5MHz * 4.2V
COUT =
IRMS =
Pesr = esr * IRMS2 = 5m * (66mA)2 = 21.8W
28
2552.2007.04.1.0
AAT2552
Total Power Solution for Portable Applications
Input Capacitor
Input Ripple VPP = 25mV CIN =
VPP IO
1 1 = = 1.38F (use 4.7F) 25mV - 5m * 4 * 1.5MHz - ESR * 4 * FS 0.2A
IRMS =
IO = 0.1Arms 2
P = esr * IRMS2 = 5m * (0.1A)2 = 0.05mW
AAT2552 Losses
IO2 * (RDSON(H) * VO + RDSON(L) * [VIN -VO]) VIN
PTOTAL =
+ (tsw * FS * IO + IQ) * VIN
=
0.22 * (0.59 * 1.8V + 0.42 * [4.2V - 1.8V]) 4.2V
+ (5ns * 1.5MHz * 0.2A + 30A) * 4.2V = 26.14mW
TJ(MAX) = TAMB + JA * PLOSS = 85C + (50C/W) * 26.14mW = 86.3C
2552.2007.04.1.0
29
AAT2552
Total Power Solution for Portable Applications
Output Voltage VOUTB (V)
0.6 0.8 0.9 1.0 1.1 1.2 1.3 1.4 1.5 1.8 1.85 2.0 2.5 3 3.3
R3 = 59k R3 (k)
R2 short, R3 open 19.6 29.4 39.2 49.9 59.0 68.1 78.7 88.7 118 124 137 187 237 267
R3 = 221k R1 (k)
R2 short, R3 open 75 113 150 187 221 261 301 332 442 464 523 715 887 1000
L1 (H)
1.5 1.5 1.5 1.5 1.5 1.5 1.5 2.2 2.7 3.0/3.3 3.0/3.3 3.0/3.3 3.9/4.2 4.9 5.6
Table 6: Step-Down Converter Component Values.
Manufacturer
Sumida Sumida Sumida Sumida Sumida Sumida Sumida Sumida Sumida Sumida Sumida Taiyo Yuden Taiyo Yuden Taiyo Yuden Taiyo Yuden FDK FDK FDK FDK
Part Number
CDRH2D09-1R5 CDRH2D09-2R2 CDRH2D09-2R5 CDRH2D09-3R0 CDRH2D09-3R9 CDRH2D09-4R7 CDRH2D09-5R6 CDRH2D11-1R5 CDRH2D11-2R2 CDRH2D11-3R3 CDRH2D11-4R7 NR3010T1R5N NR3010T2R2M NR3010T3R3M NR3010T4R7M MIPWT3226D-1R5 MIPWT3226D-2R2 MIPWT3226D-3R0 MIPWT3226D-4R2
Inductance (H)
1.5 2.2 2.5 3.0 3.9 4.7 5.6 1.5 2.2 3.3 4.7 1.5 2.2 3.3 4.7 1.5 2.2 3.0 4.2
Max DC Current (mA)
730 600 530 470 450 410 370 900 780 600 500 1200 1100 870 750 1200 1100 1000 900
DCR (m)
110 144 150 194 225 287 325 68 98 123 170 80 95 140 190 90 100 120 140
Size (mm) LxWxH
3.0x3.0x1.0 3.0x3.0x1.0 3.0x3.0x1.0 3.0x3.0x1.0 3.0x3.0x1.0 3.0x3.0x1.0 3.0x3.0x1.0 3.2x3.2x1.2 3.2x3.2x1.2 3.2x3.2x1.2 3.2x3.2x1.2 3.0x3.0x1.0 3.0x3.0x1.0 3.0x3.0x1.0 3.0x3.0x1.0 3.2x2.6x0.8 3.2x2.6x0.8 3.2x2.6x0.8 3.2x2.6x0.8
Type
Shielded Shielded Shielded Shielded Shielded Shielded Shielded Shielded Shielded Shielded Shielded Shielded Shielded Shielded Shielded Chip shielded Chip shielded Chip shielded Chip shielded
Table 7: Suggested Inductors and Suppliers.
1. For reduced quiescent current, R3 = 221k.
30
2552.2007.04.1.0
AAT2552
Total Power Solution for Portable Applications
Manufacturer
Murata Murata Murata Murata Murata Murata
Part Number
GRM21BR61A106KE19 GRM188R60J475KE19 GRM188R61A225KE34 GRM188R60J225KE19 GRM188R61A105KA61 GRM185R60J105KE26
Value (F)
10 4.7 2.2 2.2 1.0 1.0
Voltage Rating
10 6.3 10 6.3 10 6.3
Temp. Co.
X5R X5R X5R X5R X5R X5R
Case Size
0805 0603 0603 0603 0603 0603
Table 8: Surface Mount Capacitors.
2552.2007.04.1.0
31
AAT2552
Total Power Solution for Portable Applications Ordering Information
Package
TDFN34-16
Marking1
UVXYY
Part Number (Tape and Reel)2
AAT2552IRN-CAE-T1
All AnalogicTech products are offered in Pb-free packaging. The term "Pb-free" means semiconductor products that are in compliance with current RoHS standards, including the requirement that lead not exceed 0.1% by weight in homogeneous materials. For more information, please visit our website at http://www.analogictech.com/pbfree.
Legend
Voltage Adjustable (0.6) 0.9 Adjustable (1.2) 1.5 1.8 1.9 2.5 2.6 2.7 2.8 2.85 2.9 3.0 3.3 4.2 Code A B E G I Y N O P Q R S T W C
1. XYY = assembly and date code. 2. Sample stock is generally held on part numbers listed in BOLD.
32
2552.2007.04.1.0
AAT2552
Total Power Solution for Portable Applications Package Information1
TDFN34-16
3.000 0.050 1.600 0.050 Detail "A" Index Area
4.000 0.050
3.300 0.050
0.350 0.100
Top View
Bottom View
C0.3 0.230 0.050
(4x) 0.850 MAX
0.050 0.050
0.229 0.051
Side View Detail "A"
All dimensions in millimeters.
1. The leadless package family, which includes QFN, TQFN, DFN, TDFN and STDFN, has exposed copper (unplated) at the end of the lead terminals due to the manufacturing process. A solder fillet at the exposed copper edge cannot be guaranteed and is not required to ensure a proper bottom solder connection.
(c) Advanced Analogic Technologies, Inc. AnalogicTech cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in an AnalogicTech product. No circuit patent licenses, copyrights, mask work rights, or other intellectual property rights are implied. AnalogicTech reserves the right to make changes to their products or specifications or to discontinue any product or service without notice. Except as provided in AnalogicTech's terms and conditions of sale, AnalogicTech assumes no liability whatsoever, and AnalogicTech disclaims any express or implied warranty relating to the sale and/or use of AnalogicTech products including liability or warranties relating to fitness for a particular purpose, merchantability, or infringement of any patent, copyright or other intellectual property right. In order to minimize risks associated with the customer's applications, adequate design and operating safeguards must be provided by the customer to minimize inherent or procedural hazards. Testing and other quality control techniques are utilized to the extent AnalogicTech deems necessary to support this warranty. Specific testing of all parameters of each device is not necessarily performed. AnalogicTech and the AnalogicTech logo are trademarks of Advanced Analogic Technologies Incorporated. All other brand and product names appearing in this document are registered trademarks or trademarks of their respective holders.
Advanced Analogic Technologies, Inc.
830 E. Arques Avenue, Sunnyvale, CA 94085 Phone (408) 737-4600 Fax (408) 737-4611
2552.2007.04.1.0
0.450 0.050
Pin 1 Indicator (optional)
33

▲Up To Search▲

Price & Availability of AAT2552IRN-CAE-T1

	To Download AAT2552IRN-CAE-T1 Datasheet File
If you can't view the Datasheet, Please click here to try to view without PDF Reader .