AAT2557
500mA Battery Charger and 300mA LDO Regulator for Portable SystemsSystemPowerTM
PRODUCT DATASHEET
2557.2009.07.1.2 1
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General Description
The AAT2557 is a fully integrated 500mA battery charger
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 linear regulator, making it ideal
for applications operating with single-cell lithium-ion/
polymer batteries.
The battery charger is a complete constant current/con-
stant voltage linear charger. It offers an integrated pass
device, reverse blocking protection, high accuracy cur-
rent and voltage regulation, charge status, and charge
termination. The charging current is programmable via
external resistor from 15mA to 500mA. In addition to
these standard features, the device offers over-voltage,
current limit, and thermal protection.
The linear regulator is designed for fast transient
response and good power supply ripple rejection.
Capable of up to 300mA load current, it includes short-
circuit protection and thermal shutdown.
The AAT2557 is available in a Pb-free, thermally-
enhanced TSOPJW-14 package and is rated over the
-40°C to +85°C temperature range.
Features
• Battery Charger:
▪ Input Voltage Range: 4V to 6.5V
▪ Programmable Charging Current up to 500mA
▪ Highly Integrated With
• Charging Device
• Reverse Blocking Diode
• Linear Regulator:
▪ 300mA Output Current
▪ Low Dropout: 400mV at 300mA
▪ Fast Line and Load Transient Response
▪ High Accuracy: ±1.5%
▪ 70μA Quiescent Current
• Short-Circuit, Over-Temperature, and Current Limit
Protection
• TSOPJW-14 Package
• -40°C to +85°C Temperature Range
Applications
• Bluetooth™ Headsets
• Cellular and DECT Phones
• Handheld Instruments
• MP3 and Portable Music Players
• PDAs and Handheld Computers
• Portable Media Players
Typical Application
BATT-
ADP
GND
BAT
ISET
INLDO
BATT+
AAT2557
A
dapter/USB Input
STAT
EN_BAT
Charger Enable
EN_LDO
LDO Enable
RSET
C
Battery
Pack
BAT
System
OUTLDO
BYP
COUTLDO CBYP
VOUTLDO
CINLDO
AAT2557
500mA Battery Charger and 300mA LDO Regulator for Portable SystemsSystemPowerTM
PRODUCT DATASHEET
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AAT2557
500mA Battery Charger and 300mA LDO Regulator for Portable SystemsSystemPowerTM
PRODUCT DATASHEET
2 2557.2009.07.1.2
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Pin Descriptions
Pin # Symbol Function
1 EN_LDO Enable pin for the linear regulator. When connected to logic low, the regulator is disabled and con-
sumes less than 1μA of current. When connected to logic high, it resumes normal operation.
2, 8, 12, 13, 14 GND Ground.
3 BYP Low noise bypass pin. Connect a 10nF capacitor between this pin and ground to improve AC ripple
rejection and reduce noise.
4 EN_BAT
Enable pin for the battery charger. When connected to logic low, the battery charger is disabled
and consumes less than 1μA of current. When connected to logic high, the charger resumes nor-
mal operation.
5 ISET Charge current set point. Connect a resistor from this pin to ground. Refer to typical characteristics
curves for resistor selection.
6 BAT Battery charging and sensing.
7 ADP Input for USB/adapter charger.
9 STAT Charge status input. Open drain status output.
10 OUTLDO Linear regulator output. Connect a 2.2μF capacitor from this pin to ground.
11 INLDO Linear regulator input voltage. Connect a 1μF or greater capacitor from this pin to ground.
Pin Configuration
TSOPJW-14
(Top View)
1
2
3
4
5
6
14
13
12
11
10
9
EN_LDO
GND
BYP
EN_BAT
ISET
BAT
GND
GND
GND
INLDO
OUTLD
O
STAT
7 8
ADP GND
AAT2557
500mA Battery Charger and 300mA LDO Regulator for Portable SystemsSystemPowerTM
PRODUCT DATASHEET
2557.2009.07.1.2 3
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AAT2557
500mA Battery Charger and 300mA LDO Regulator for Portable SystemsSystemPowerTM
PRODUCT DATASHEET
2557.2009.07.1.2 3
www.analogictech.com
Absolute Maximum Ratings1
Symbol Description Value Units
VINLDO Input Voltage to GND 6.0 V
VADP Adapter Voltage to GND -0.3 to 7.5 V
VEN EN_LDO, EN_BAT Voltage to GND -0.3 to 6.0 V
VXBAT, ISET, STAT Voltage to GND -0.3 to VADP + 0.3 V
VBYP BYP Voltage to GND -0.3 to VINLDO + 0.3 V
TJJunction Temperature Range -40 to 150 °C
TAOperating Temperature Range -40 to 85 °C
TLEAD Maximum Soldering Temperature (at leads, 10 sec) 300 °C
Thermal Information
Symbol Description Value Units
PDMaximum Power Dissipation 625 mW
θJA Thermal Resistance2160 °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.
AAT2557
500mA Battery Charger and 300mA LDO Regulator for Portable SystemsSystemPowerTM
PRODUCT DATASHEET
4 2557.2009.07.1.2
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AAT2557
500mA Battery Charger and 300mA LDO Regulator for Portable SystemsSystemPowerTM
PRODUCT DATASHEET
4 2557.2009.07.1.2
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Electrical Characteristics1
VINLDO = VOUTLDO(NOM) + 1V for VOUTLDO options greater than 1.5V. IOUTLDO = 1mA, COUTLDO = 2.2μF, C INLDO = 1μF, C BYP = 10nF,
TA = -40°C to +85°C, unless otherwise noted. Typical values are TA = 25°C.
Symbol Description Conditions Min Typ Max Units
Linear Regulator
VOUTLDO Output Voltage Tolerance IOUTLDO = 1mA to
300mA
TA = 25°C -1.5 1.5 %
TA = -40°C
to +85°C -2.5 2.5
VINLDO Input Voltage VOUTLDO +
VDOLDO25.5 V
VDOLDO Dropout Voltage3IOUTLDO = 300mA 400 600 mV
ΔVOUT/
VOUTLDO*ΔVINLDO
Line Regulation VINLDO = VOUTLDO + 1 to 5.0V 0.09 %/V
ΔVOUTLDO(Line) Dynamic Line Regulation
IOUTLDO = 300mA, VINLDO =
VOUTLDO + 1 to VOUTLDO + 2, TR/
TF = 2μs
2.5 mV
ΔVOUTLDO(Load) Dynamic Load Regulation IOUTLDO = 1mA to 300mA, TR
<5μs60 mV
IOUTLDO Output Current VOUTLDO > 1.2V 300 mA
ISC Short-Circuit Current VOUTLDO < 0.4V 600 mA
IQLDO Quiescent Current VINLDO = 5V; VEN_LDO = VIN 70 125 μA
ISHDN Shutdown Current VINLDO = 5V; VEN_LDO = 0V 1.0 μA
PSRR Power Supply Rejection Ratio IOUTLDO =10mA
1kHz 65
dB10kHz 45
1MHz 43
TSD Over-Temperature Shutdown Threshold 145 °C
THYS Over-Temperature Shutdown Hysteresis 12 °C
eNOutput Noise 50 μVRMS
TCOutput Voltage Temperature Coeffi cient 22 ppm/°C
TEN_LDO_DLY LDO Enable Time Delay BYP Open 15 μs
VEN_LDO(L) LDO Enable Threshold Low 0.6 V
VEN_LDO(H) LDO Enable Threshold High 1.5 V
IEN_LDO LDO Enable Input Current VEN_LDO = 5.5V 1.0 μA
1. The AAT2557 is guaranteed to meet performance specifications over the -40°C to +85°C operating temperature range and is assured by design, characterization, and correla-
tion 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
.
AAT2557
500mA Battery Charger and 300mA LDO Regulator for Portable SystemsSystemPowerTM
PRODUCT DATASHEET
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AAT2557
500mA Battery Charger and 300mA LDO Regulator for Portable SystemsSystemPowerTM
PRODUCT DATASHEET
2557.2009.07.1.2 5
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Electrical Characteristics1
VADP = 5V; TA = -40°C to +85°C, unless otherwise noted. Typical values are TA = 25°C.
Symbol Description Conditions Min Typ Max Units
Battery Charger
Operation
VADP Adapter Voltage Range 4.0 6.5 V
VUVLO
Under-Voltage Lockout (UVLO) Rising Edge 3.0 4.0 V
UVLO Hysteresis 150 mV
IOP Operating Current Charge Current = 200mA 0.5 1 mA
ISHUTDOWN Shutdown Current VBAT = 4.25V, EN_BAT = GND 0.3 1 μA
ILEAKAGE Reverse Leakage Current from BAT Pin VBAT = 4V, ADP Pin Open 0.4 2 μA
Voltage Regulation
VCO(REG) Output Charge Voltage Regulation 4.158 4.20 4.242 V
ΔVCH/VCH Output Charge Voltage Tolerance 0.5 %
VMIN Preconditioning Voltage Threshold 2.85 3.0 3.15 V
VRCH Battery Recharge Voltage Threshold Measured from VCO(REG)
VCO(REG) -
0.1 V
Current Regulation
ICH_CC Charge Current Programmable Range 15 500 mA
ΔICH_CC/
ICH_CC
Charge Current Regulation Tolerance 10 %
VISET ISET Pin Voltage 2V
KI_A Current Set Factor: ICH/ISET 800
Charging Devices
RDS(ON) Charging Transistor On Resistance VADP = 5.5V 0.9 1.1 Ω
Logic Control/Protection
VEN_BAT(H) Battery Charger Enable Threshold High 1.6 V
VEN_BAT(L) Battery Charger Enable Threshold Low 0.4 V
VSTAT STAT Pin Output Low Voltage STAT Pin Sinks 4mA 0.4 V
ISTAT STAT Pin Current Sink Capability 8mA
VOVP Battery Over-Voltage Protection Threshold 4.4 V
ICH_TKL/
ICH_CC
Preconditioning Charge Current ICH = 100mA 10 %
ICH_TERM/
ICH_CC
Charge Termination Current 10 %
1. The AAT2557 is guaranteed to meet performance specifications over the -40°C to +85°C operating temperature range and is assured by design, characterization, and correla-
tion with statistical process controls.
AAT2557
500mA Battery Charger and 300mA LDO Regulator for Portable SystemsSystemPowerTM
PRODUCT DATASHEET
6 2557.2009.07.1.2
www.analogictech.com
AAT2557
500mA Battery Charger and 300mA LDO Regulator for Portable SystemsSystemPowerTM
PRODUCT DATASHEET
6 2557.2009.07.1.2
www.analogictech.com
Typical Characteristics – Battery Charger
RSET (kΩ
Ω
)
ICH (mA)
Constant Charging Current
vs. Set Resistor Values
1
10
100
1000
1 10 100 1000
Charging Current vs. Battery Voltage
(VADP = 5V)
VBAT (V)
ICH (mA)
0
100
200
300
400
500
600
2.7 2.9 3.1 3.3 3.5 3.7 3.9 4.1 4.
3
RSET = 8.06kΩ
RSET = 5.36kΩ
RSET = 3.24kΩ
RSET = 16.2kΩRSET = 31.6kΩ
Constant Output Charge Voltage
Regulation vs. Adapter Voltage
VADP (V)
VCO_REG (V)
4.194
4.196
4.198
4.200
4.202
4.204
4.206
4.5 4.75 5 5.25 5.5 5.75 6 6.25 6.5
RSET = 8.06kΩ
RSET = 31.6kΩ
Constant Output Charge Voltage
Regulation vs. Temperature
(RSET = 8.06kΩ
Ω
)
Temperature (
°
C)
VCO(REG) (V)
4.17
4.18
4.19
4.20
4.21
4.22
4.23
-50 -25 0 25 50 75 100
Constant Charging Current vs.
Adapter Voltage
(RSET = 8.06kΩ
Ω
)
VADP (V)
ICH (mA)
170
180
190
200
210
220
4 4.25 4.5 4.75 5 5.25 5.5 5.75 6 6.25
6.5
VBAT = 3.6V
VBAT = 4V
VBAT = 3.3V
Constant Charging Current vs. Temperature
(RSET = 8.06kΩ
Ω
)
Temperature (
°
C)
ICH (mA)
190
193
195
198
200
203
205
208
210
-50 -25 0 25 50 75 100
AAT2557
500mA Battery Charger and 300mA LDO Regulator for Portable SystemsSystemPowerTM
PRODUCT DATASHEET
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AAT2557
500mA Battery Charger and 300mA LDO Regulator for Portable SystemsSystemPowerTM
PRODUCT DATASHEET
2557.2009.07.1.2 7
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Typical Characteristics – Battery Charger
Recharging Voltage Threshold
vs. Temperature
(RSET = 8.06kΩ
Ω
)
Temperature (
°
C)
VRCH (V)
4.02
4.04
4.06
4.08
4.10
4.12
4.14
4.16
4.18
-50 -25 0 25 50 75 100
Preconditioning Voltage Threshold
vs. Temperature
(RSET = 8.06kΩ
Ω
)
Temperature (
°
C)
VMIN (V)
2.97
2.98
2.99
3
3.01
3.02
3.03
-50 -25 0 25 50 75 100
Preconditioning Charge Current
vs. Temperature
(RSET = 8.06kΩ
Ω
)
Temperature (
°
C)
ITRICKLE (mA)
19.2
19.4
19.6
19.8
20.0
20.2
20.4
20.6
20.8
-50 -25 0 25 50 75 100
Preconditioning Charge Current
vs. Adapter Voltage
VADP (V)
ITRICKLE (mA)
0
10
20
30
40
50
60
4 4.2 4.4 4.6 4.8 5 5.2 5.4 5.6 5.8 6 6.2 6.4
RSET = 8.06kΩ
RSET = 5.36kΩ
RSET = 3.24kΩ
RSET = 16.2kΩRSET = 31.6kΩ
Operating Current vs. Temperature
(RSET = 8.06kΩ
Ω
)
Temperature (
°
C)
IOP (µA)
300
350
400
450
500
550
-50 -25 0 25 50 75 100
Sleep Mode Current vs. Supply Voltage
(RSET = 8.06kΩ
Ω
)
VADP (V)
ISLEEP (nA)
0
100
200
300
400
500
600
700
800
4 4.25 4.5 4.75 5 5.25 5.5 5.75 6 6.25 6.5
85°C
25°C-40°C
AAT2557
500mA Battery Charger and 300mA LDO Regulator for Portable SystemsSystemPowerTM
PRODUCT DATASHEET
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AAT2557
500mA Battery Charger and 300mA LDO Regulator for Portable SystemsSystemPowerTM
PRODUCT DATASHEET
8 2557.2009.07.1.2
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Typical Characteristics – Battery Charger
Enable Input High Voltage vs. Adapter Voltage
(RSET = 8.06kΩ
Ω
)
VADP (V)
VEN_BAT(H) (V)
0.7
0.8
0.9
1
1.1
1.2
4 4.25 4.5 4.75 5 5.25 5.5 5.75 6 6.25 6.5
-40°C
25°C85°C
Enable Input Low Voltage vs. Adapter Voltage
(RSET = 8.06kΩ
Ω
)
VADP (V)
VEN_BAT(L) (V)
0.6
0.7
0.8
0.9
1
1.1
4 4.25 4.5 4.75 5 5.25 5.5 5.75 6 6.25 6.5
-40°C
25°C85°C
Typical Characteristics – LDO Regulator
Enable Input High and Low Voltages
vs. Input Voltage
1.050
1.075
1.100
1.125
1.150
1.175
1.200
1.225
1.250
2.5 3.0 3.5 4.0 4.5 5.0 5.5
Input Voltage (V)
VEN_LDO(L) and VEN_LDO(H) (V)
VEN(H)
VEN(L)
Dropout Voltage vs. Temperature
0
60
120
180
240
300
360
420
480
540
-40 -30 -20 -10 0 10 20 30 40 50 60 70 80 90 100 110 120
Temperature (
°
C)
Dropout Voltage (mV)
IL = 300mA
IL = 150mA IL = 100mA
IL = 50mA
Dropout Characteristics
2.0
2.2
2.4
2.6
2.8
3.0
3.2
2.7 2.8 2.9 3.0 3.1 3.2 3.3
IOUT = 300mA
IOUT = 150mA
IOUT = 100mA
IOUT = 50mA
IOUT = 10mA
IOUT = 0mA
Input Voltage (V)
Output Voltage (V)
Dropout Voltage vs. Output Current
0
50
100
150
200
250
300
350
400
450
500
0 50 100 150 200 250 300
Output Current (mA)
Dropout Voltage (mV)
85°C
25°C
-40°C
AAT2557
500mA Battery Charger and 300mA LDO Regulator for Portable SystemsSystemPowerTM
PRODUCT DATASHEET
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AAT2557
500mA Battery Charger and 300mA LDO Regulator for Portable SystemsSystemPowerTM
PRODUCT DATASHEET
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Typical Characteristics – LDO Regulator
Ground Current vs. Input Voltage
0
10
20
30
40
50
60
70
80
90
2 2.5 3 3.5 4.54
5
Input Voltage (V)
Ground Current (
μ
A)
IOUT=0mA
IOUT=10mA
IOUT=50mA
IOUT=150mA
IOUT=300mA
Quiescent Current vs. Temperature
0
10
20
30
40
50
60
70
80
90
100
-40 -30 -20 -10 0 10 20 30 40 50 60 70 80 90 100 110 120
Temperature (
°
C)
Quiescent Current (
μ
A)
Output Voltage vs. Temperature
1.196
1.197
1.198
1.199
1.200
1.201
1.202
1.203
-40 -30 -20 -10 0 10 20 30 40 50 60 70 80 90 100
Temperature (
°
C)
Output Voltage (V)
LDO Initial Turn-On Response Time
Time (50µs/div)
Input Voltage (top) (V)
Output Voltage (bottom) (V)
0
1
2
3
4
5
6
0
1
2
3
LDO Turn-On Time from Enable
(VIN Present)
Time (5µs/div)
Enable Voltage (top) (V)
Output Voltage (bottom) (V)
0
1
2
3
4
0
1
2
3
4
LDO Turn-Off Response Time
(IOUT = 100mA)
Time (5µs/div)
Enable Voltage (top) (V)
Output Voltage (bottom) (V)
0
1
2
3
0
5
AAT2557
500mA Battery Charger and 300mA LDO Regulator for Portable SystemsSystemPowerTM
PRODUCT DATASHEET
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AAT2557
500mA Battery Charger and 300mA LDO Regulator for Portable SystemsSystemPowerTM
PRODUCT DATASHEET
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Typical Characteristics – LDO Regulator
Line Transient Response
2.98
2.99
3.00
Time (100µs/div)
Input Voltage (top) (V)
4
5
6
Output Voltage (bottom) (V)
VIN
VOUT
Load Transient Response
(VOUT = 2.8V)
2.75
2.80
2.85
2.90
Time (100µs/div)
Output Voltage (top) (V)
0
100
Output Current (bottom) (mA)
VOUT
IOUT
Load Transient Response 300mA
(VOUT = 2.8V)
2.7
2.8
2.9
3.0
Time (10µs/div)
0
100
200
300
400
VOUT
IOUT
Output Voltage (top) (V)
Output Current (bottom) (mA)
AAT2557
500mA Battery Charger and 300mA LDO Regulator for Portable SystemsSystemPowerTM
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Functional Block Diagram
Reverse Blocking
VREF
Constant
Current
Over-
Temperature
Protection
Charge
Control
BAT
UVLO
Over-
Current
Protection
STAT
GND
+
+
-
ISET
ADP
EN_BAT
BYP
Err.
Amp.
OUTLDO
INLDO
EN_LDO
VREF
-
Functional Description
The AAT2557 is a high performance power management
IC comprised of a lithium-ion/polymer battery charger
and a linear regulator.
Battery Charger
The battery charger is designed for single-cell lithium-
ion/polymer batteries using a constant current and con-
stant 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 applica-
tions. 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. Fault condition can
be one of the following:
• Battery over-voltage (OV)
• Battery temperature sense hot or cold
• Battery charge timer time-out
• Chip thermal shutdown
In the event of an over-voltage or over-temperature fail-
ure, 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.
AAT2557
500mA Battery Charger and 300mA LDO Regulator for Portable SystemsSystemPowerTM
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Linear Regulator
The advanced circuit design of the linear regulator has
been specifically optimized for very fast start-up. This
proprietary CMOS LDO has also been tailored for supe-
rior 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 con-
trol and feedback circuits within the LDO regulator. The
LDO regulator output has been specifically optimized to
function with low-cost, 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 ther-
mal 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. The
EN_LDO pin is active high and is compatible with CMOS
logic levels. To assure the LDO regulator will turn on, the
EN_LDO control level must be greater than 1.5V. The
LDO regulator will be disabled when the voltage on the
EN_LDO pin falls below 0.6V. If the enable function is not
needed in a specific application, it may be tied to INLDO
to keep the LDO regulator in a continuously on state.
Battery Charger Under-Voltage Lockout
The AAT2557 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.
Protection Circuitry
Over-Voltage Protection
When the voltage on the BAT pin exceeds the over-
voltage protection threshold (VOVP = 4.4V) it is defined
as an over-voltage protection event. If this over-voltage
condition occurs, the charger control circuitry will shut
down the device. The charger will resume normal charg-
ing operation after the over-voltage condition is
removed.
Over-Temperature Protection
The AAT2557’s battery charger has a thermal protection
circuit which will shut down charging functions when the
internal die temperature exceeds the preset thermal
limit threshold (145°C). Once the internal die tempera-
ture falls below the thermal limit, normal charging
operation will resume. The AAT2557’s LDO also has an
internal thermal protection circuit which will turn on
when the device die temperature exceeds 145°C. The
internal thermal protection circuit will actively turn off
the LDO regulator output pass device to prevent the
possibility of over temperature damage. The LDO regu-
lator output will remain in a shutdown state until the
internal die temperature falls back to 12°C below the
145°C trip point.
Short-Circuit Protection
The AAT2557’s LDO contains an internal short-circuit
protection circuit that will trigger when the output load
current exceeds the internal threshold limit. Under
short-circuit conditions, the output of the LDO regulator
will be current limited until the short-circuit condition is
removed from the output or until the package power dis-
sipation exceeds the device thermal limit.
The combination and interaction between the short-cir-
cuit and thermal protection systems allow the LDO regu-
lator to withstand indefinite short-circuit conditions
without sustaining permanent damage.
AAT2557
500mA Battery Charger and 300mA LDO Regulator for Portable SystemsSystemPowerTM
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Battery Charging Operation
Battery charging commences only after checking several
conditions in order to maintain a safe charging environ-
ment. The input supply (ADP) must be above the mini-
mum 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 condi-
tion 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 pro-
grammed 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 MOSFET pass device when the input-output volt-
age 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 current 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 and
the battery charger begins constant voltage mode. The
regulation voltage is factory programmed to a nominal
4.2V and will continue charging until the charging cur-
rent 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-sav-
ing sleep mode. During this time, the series pass device
will block current in both directions, preventing the bat-
tery from discharging through the IC.
The battery charger will remain in sleep mode, even if
the charger source is disconnected, until one of the fol-
lowing 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.
ICH_CC
Recharge Phase
ICH_TKL
VUVLO
VMIN
VCO( REG)
VRCH
ICH_TERM
when
VBAT=
VCO( REG)
ICH_TERM
when
VBAT=
VCO( REG)
Constant Voltage Charge
Phase (CV)
Constant Current
Charge Phase (CC)
Trickle
ChargeUVLO
Battery Constant Voltage Charge
Phase
Constant Current
Charge Phase
Termination
Phase
Termination
Phase
ICH_CC
Figure 1: Current vs. Voltage Profile During Charging Phases.
AAT2557
500mA Battery Charger and 300mA LDO Regulator for Portable SystemsSystemPowerTM
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AAT2557
500mA Battery Charger and 300mA LDO Regulator for Portable SystemsSystemPowerTM
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Battery Charging System Operation Flow Chart
Power On Reset
Power Input
Voltage
VADP > VUVLO
Fault Conditions
Monitoring
OV, OT
Preconditioning
Test
VMIN > VBAT
Current Phase Test
VCO(REG) > VBAT
Voltage Phase Test
IBAT > ICH_TERM
No
No
Yes
No
Preconditioning
(Trickle Charge)
Constant
Current Charge
Mode
Constant
Voltage Charge
Mode
Yes
Yes
Yes
Charge Completed
Charge
Control
No
Recharge Test
VRCH > VBAT
Yes
No
Shut Down Yes
Enable
Yes
No
AAT2557
500mA Battery Charger and 300mA LDO Regulator for Portable SystemsSystemPowerTM
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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 re-enabled, the charge con-
trol 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.
The LDO is enabled when the EN_LDO pin is pulled high.
The control and feedback circuits have been optimized
for high-speed, monotonic turn-on characteristics.
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.
Programming Charge Current
The fast charge constant current charge level is user
programmable with a set resistor placed between the
ISET pin and ground. The accuracy of 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 recom-
mended for the set resistor function. Fast charge con-
stant current levels from 15mA to 500mA may be set by
selecting the appropriate resistor value from Table 2.
Charge Status Output
The AAT2557 provides battery charge status via a status
pin. This pin is internally connected to an N-channel
open drain MOSFET, which can be used to drive an exter-
nal LED. The status pin can indicate several conditions,
as shown in Table 1.
Event Description Status
No battery charging activity OFF
Battery charging via adapter or USB port ON
Charging completed OFF
Table 1: LED Status Indicator.
Constant Charge
Current ICH_CC (mA)
Set Resistor Value
(kΩ)
500 3.24
400 4.12
300 5.36
250 6.49
200 8.06
150 10.7
100 16.2
50 31.6
40 38.3
30 53.6
20 78.7
15 105
Table 2: RSET Values.
RSET (kΩ
Ω
)
ICH_CC (mA)
1
10
100
1000
1 10 100 1000
Figure 2: Constant Charging Current
vs. Set Resistor Values.
The LED should be biased with as little current as neces-
sary to create reasonable illumination; therefore, a bal-
last 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 pack-
age, 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.
AAT2557
500mA Battery Charger and 300mA LDO Regulator for Portable SystemsSystemPowerTM
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The required ballast resistor values can be estimated
using the following formulas:
(V
ADP -
V
F(LED)
)
R
1
=I
LED
Example:
(5.5V
- 2.0
V)
R
1
= = 1.75kΩ
2mA
Note: Red LED forward voltage (VF) is typically 2.0V @
2mA.
Thermal Considerations
The AAT2557 is offered in a TSOPJW-14 package which
can provide up to 625mW of power dissipation when it
is properly bonded to a printed circuit board and has a
maximum thermal resistance of 160°C/W. Many consid-
erations 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 appli-
cation. The maximum limits that can be expected for a
given ambient condition can be estimated by the follow-
ing discussion.
First, the maximum power dissipation for a given situa-
tion should be calculated:
(T
J(MAX) -
T
A
)
P
D(MAX)
= θ
JA
Where:
PD(MAX) = Maximum Power Dissipation (W)
θJA = Package Thermal Resistance (°C/W)
TJ(MAX) = Maximum Device Junction Temperature (°C)
[135°C]
TA = Ambient Temperature (°C)
PD = [(VADP - VBAT) · ICH + (VADP · IOP)] + (VINLDO - VOUTLDO) IOUTLDO + VINLDO · IQLDO
Where:
PD = Total Power Dissipation by the Device
VADP = ADP/USB Voltage
VBAT = Battery Voltage as Seen at the BAT Pin
ICH = Constant Charge Current Programmed for the
Application
IOP = Quiescent Current Consumed by the Charger
IC for Normal Operation [0.5mA]
VINLDO = Input Voltage as Seen at the INLDO Pin
VOUTLDO = Output Voltage as Seen at the OUTLDO Pin
IOUTLDO = LDO Load Current
IQLDO = LDO Quiescent Current
By substitution, we can derive the maximum charge cur-
rent before reaching the thermal limit condition (thermal
cycling). The maximum charge current is the key factor
when designing battery charger applications.
(P
D(MAX) -
V
IN
·
I
OP
)
V
IN
- V
BAT
I
CH(MAX)
=
(T
J(MAX) -
T
A
)
θ
JA
V
IN
- V
BAT
I
CH(MAX)
=
-
V
IN
·
I
OP
In general, the worst condition is the greatest voltage
drop across the IC, when battery voltage is charged up
to the preconditioning voltage threshold.
Capacitor Selection
Linear Regulator Input Capacitor
An input capacitor greater than 1μF will offer superior
input line transient response and maximize power sup-
ply ripple rejection. Ceramic, tantalum, or aluminum
electrolytic capacitors may be selected since there is no
specific capacitor ESR requirement for CINLDO. However,
for best performance of the LDO regulator at maximum
load current output, ceramic capacitors are recommend-
ed for CINLDO due to their inherent capability over tanta-
lum capacitors to withstand input current surges from
low impedance sources such as batteries in portable
devices.
AAT2557
500mA Battery Charger and 300mA LDO Regulator for Portable SystemsSystemPowerTM
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Battery Charger Input Capacitor
In general, it is good design practice to place a decou-
pling capacitor between the ADP pin and GND. An input
capacitor in the range of 1μF to 22μF 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 CADP capacitor in the range of 10μF
should be used. A larger input capacitor in this applica-
tion will minimize switching or power transient effects
when the power supply is “hot plugged” in.
Linear Regulator Output Capacitor
For proper load voltage regulation and operational stabil-
ity, a capacitor is required between OUT and GND. The
COUTLDO 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 1.0μF to 10μF range are rec-
ommended for best performance. Applications utilizing
the exceptionally low output noise and optimum power
supply ripple rejection should use 2.2μF or greater for
COUTLDO. In low output current applications, where output
load is less than 10mA, the minimum value for COUTLDO
can be as low as 0.47μF.
Battery Charger Output Capacitor
The AAT2557 only requires a 1μF ceramic capacitor on
the BAT pin to maintain circuit stability. This value should
be increased to 10μF or more if the battery connection is
made any distance from the charger output. If the
AAT2557 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 10μF
may be required to prevent the device from cycling on
and off when no battery is present.
Bypass Capacitor and Low Noise Applications
A bypass capacitor pin is provided to enhance the low
noise characteristics of the AAT2557 LDO regulator. The
bypass capacitor is not necessary for operation of the
AAT2557. However, for best device performance, a small
ceramic capacitor should be placed between the bypass
pin (BYP) and the device ground pin (GND). The value of
CBYP may range from 470pF to 10nF. For lowest noise and
best possible power supply ripple rejection performance,
a 10nF capacitor should be used. To practically realize
the highest power supply ripple rejection and lowest
output noise performance, it is critical that the capacitor
connection between the BYP pin and GND pin be direct
and PCB traces should be as short as possible. Refer to
the PCB Layout Recommendations section of this docu-
ment for examples.
There is a relationship between the bypass capacitor
value and the LDO regulator turn-on and turnoff time. In
applications where fast device turn-on and turn-off time
are desired, the value of CBYP should be reduced.
In applications where low noise performance and/or
ripple rejection are less of a concern, the bypass capac-
itor may be omitted. The fastest device turn-on time will
be realized when no bypass capacitor is used.
Printed Circuit Board
Layout Considerations
For the best results, it is recommended to physically
place the battery pack as close as possible to the
AAT2557 BAT pin. To minimize voltage drops on the PCB,
keep the high current carrying traces adequately wide.
The input capacitors should connect as closely as possi-
ble to ADP and INLDO.
Manufacturer Part Number Value (μF) Voltage Rating Temp. Co. Case Size
Murata GRM21BR61A106KE19 10 10 X5R 0805
Murata GRM188R60J475KE19 4.7 6.3 X5R 0603
Murata GRM188R61A225KE34 2.2 10 X5R 0603
Murata GRM188R60J225KE19 2.2 6.3 X5R 0603
Murata GRM188R61A105KA61 1.0 10 X5R 0603
Murata GRM185R60J105KE26 1.0 6.3 X5R 0603
Murata GRM188F51H103ZA01 0.01 50 Y5V 0603
Murata GRM155F51H103ZA01 0.01 50 Y5V 0402
Table 3: Surface Mount Capacitors.
AAT2557
500mA Battery Charger and 300mA LDO Regulator for Portable SystemsSystemPowerTM
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AAT2557
500mA Battery Charger and 300mA LDO Regulator for Portable SystemsSystemPowerTM
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Figure 3: AAT2557 Evaluation Board Figure 4: AAT2557 Evaluation Board
Top Side Layout. Bottom Side Layout.
R2 1.5k
R1
8.06k
C3
4.7μF
C5
10nF
C4
2.2μF
C2
10μF
C1
10μF
TB2
BAT
JP1
JP2
JP3
D1
GND GND
ADP
7
STAT
9
EN_BAT
4
EN_LDO
1
OUTLDO
10
BYP
3
INLDO 11
ISET 5
BAT 6
GND 2
GND
8
GND 12
GND 13
GND 14
U1
AAT2557ITO
GND
INLDO
GND
GND
INLDO
TSOPJW-14
TB1
ADP
GND
TP1
EN_LDO
INLDO
Figure 5: AAT2557 Evaluation Board Schematic.
AAT2557
500mA Battery Charger and 300mA LDO Regulator for Portable SystemsSystemPowerTM
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500mA Battery Charger and 300mA LDO Regulator for Portable SystemsSystemPowerTM
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Ordering Information
Package Marking1Part Number (Tape and Reel)2
TSOPJW-14 VKXYY AAT2557ITO-CT-T1
TSOPJW-14 9ZXYY AAT2557ITO-CW-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/about/quality.aspx.
Legend
Voltage Code
1.2 E
1.5 G
1.8 I
1.9 Y
2.5 N
2.6 O
2.7 P
2.8 Q
2.85 R
2.9 S
3.0 T
3.3 W
4.2 C
1. XYY = assembly and date code.
2. Sample stock is generally held on part numbers listed in BOLD.
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500mA Battery Charger and 300mA LDO Regulator for Portable SystemsSystemPowerTM
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500mA Battery Charger and 300mA LDO Regulator for Portable SystemsSystemPowerTM
PRODUCT DATASHEET
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Advanced Analogic Technologies, Inc.
3230 Scott Boulevard, Santa Clara, CA 95054
Phone (408) 737-4600
Fax (408) 737-4611
© 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 specifi cations 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 fi tness 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. Specifi c 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.
Package Information
TSOPJW-14
2.40 ± 0.10
2.85 ± 0.20
0.40 BSC
0.20 + 0.10
- 0.05
0.15 ± 0.05
0.04 REF
0.45 ± 0.1
5
2.75 ± 0.25
4° ± 4°
1.05 + 0.05
- 0.00
1.00 + 0.000
- 0.075
3.05 + 0.05
- 0.10
0.05 + 0.05
- 0.04
Top View
Side View End View
All dimensions in millimeters.
