ANALOGICTECH AAT2557ITO-CT-T1

AAT2557
500mA Battery Charger and 300mA
LDO Regulator for Portable Systems
General Description
Features
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/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 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.
SystemPower™
Battery Charger:
— Input Voltage Range: 4V to 6.5V
— Programmable Charging Current up to
500mA
— Highly Integrated Battery Charger
• 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
The AAT2557 is available in a Pb-free, thermallyenhanced TSOPJW-14 package and is rated over
the -40°C to +85°C temperature range.
•
•
•
•
•
•
Bluetooth® Headsets
Cellular and DECT Phones
Handheld Instruments
MP3 and Portable Music Players
PDAs and Handheld Computers
Portable Media Players
Typical Application
Adapter/USB Input
ADP
INLDO
STAT
Charger Enable
C INLDO
EN_BAT
BATT+
BAT
ENLDO
VOUTLDO
C BAT
OUTLDO
C OUTLDO
ISET
BYP
C BYP
System
AAT2557
LDO Enable
GND
BATTRSET
Battery
Pack
2557.2007.06.1.0
1
AAT2557
500mA Battery Charger and 300mA
LDO Regulator for Portable Systems
Pin Descriptions
Pin #
Symbol
Function
1
ENLDO
2, 8, 12, 13, 14
3
GND
BYP
4
EN_BAT
5
ISET
6
7
9
10
11
BAT
ADP
STAT
OUTLDO
INLDO
Enable pin for the linear regulator. When connected to logic low, the regulator is disabled and consumes less than 1µA of current. When connected to logic high, it
resumes normal operation.
Ground.
Low noise bypass pin. Connect a 10nF capacitor between this pin and ground to
improve AC ripple rejection and reduce noise.
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 normal operation.
Charge current set point. Connect a resistor from this pin to ground. Refer to typical
characteristics curves for resistor selection.
Battery charging and sensing.
Input for USB/adapter charger.
Charge status input. Open drain status output.
Linear regulator output. Connect a 2.2µF capacitor from this pin to ground.
Linear regulator input voltage. Connect a 1µF or greater capacitor from this pin to
ground.
Pin Configuration
TSOPJW-14
(Top View)
ENLDO
GND
BYP
EN_BAT
ISET
BAT
ADP
2
1
14
2
13
3
12
4
11
5
10
6
9
7
8
GND
GND
GND
INLDO
OUTLDO
STAT
GND
2557.2007.06.1.0
AAT2557
500mA Battery Charger and 300mA
LDO Regulator for Portable Systems
Absolute Maximum Ratings1
Symbol
VINLDO
VADP
VEN
VX
VBYP
TJ
TLEAD
Description
Input Voltage to GND
Adapter Voltage to GND
ENLDO, EN_BAT Voltage to GND
BAT, ISET, STAT Voltage to GND
BYP Voltage to GND
Operating Junction Temperature Range
Maximum Soldering Temperature (at leads, 10 sec)
Value
Units
6.0
-0.3 to 7.5
-0.3 to 6.0
-0.3 to VADP + 0.3
-0.3 to VINLDO + 0.3
-40 to 150
300
V
V
V
V
V
°C
°C
Value
Units
625
160
mW
°C/W
Thermal Information
Symbol
PD
θJA
Description
Maximum Power Dissipation
Thermal Resistance2
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.
2557.2007.06.1.0
3
AAT2557
500mA Battery Charger and 300mA
LDO Regulator for Portable Systems
Electrical Characteristics1
VINLDO = VOUT(NOM) + 1V for VOUT options greater than 1.5V. IOUT = 1mA, COUT = 2.2µF, CIN = 1µF, CBYP = 10nF,
TA = -40°C to +85°C, unless otherwise noted. Typical values are TA = 25°C.
Symbol
Description
Conditions
Min
Typ
Max
Units
1.5
2.5
%
5.5
V
600
mV
Linear Regulator
VOUT
VIN
VDO
ΔVOUT/
VOUT*ΔVIN
ΔVOUT(Line)
ΔVOUT(Load)
IOUT
ISC
IQ
ISHDN
PSRR
TSD
THYS
eN
TC
TEN_DLY
VEN(L)
VEN(H)
IEN
Output Voltage Tolerance
IOUTLDO = 1mA TA = 25°C
to 300mA
TA = -40°C to +85°C
Input Voltage
-1.5
-2.5
VOUT +
VDO2
Dropout Voltage3
IOUTLDO = 300mA
400
Line Regulation
VINLDO = VOUTLDO + 1 to 5.0V
0.09
%/V
2.5
mV
60
mV
mA
mA
µA
µA
IOUTLDO = 300mA, VINLDO = VOUTLDO + 1
to VOUTLDO + 2, TR/TF = 2µs
Dynamic Load Regulation IOUTLDO = 1mA to 300mA, TR <5µs
Output Current
VOUTLDO > 1.2V
Short-Circuit Current
VOUTLDO < 0.4V
Quiescent Current
VINLDO = 5V; VENLDO = VIN
Shutdown Current
VINLDO = 5V; VENLDO = 0V
1kHz
Power Supply Rejection
IOUTLDO =10mA 10kHz
Ratio
1MHz
Over-Temperature
Shutdown Threshold
Over-Temperature
Shutdown Hysteresis
Output Noise
Output Voltage
Temperature Coefficient
Enable Time Delay
BYP Open
Enable Threshold Low
Enable Threshold High
Enable Input Current
VENLDO = 5.5V
Dynamic Line Regulation
300
600
70
125
1.0
65
45
43
dB
145
°C
12
°C
50
µVRMS
22
ppm/°C
15
µs
V
V
µA
0.6
1.5
1.0
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 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.
4
2557.2007.06.1.0
AAT2557
500mA Battery Charger and 300mA
LDO Regulator for Portable Systems
Electrical Characteristics1
VADP = 5V; TA = -40°C to +85°C, unless otherwise noted. Typical values are TA = 25°C.
Symbol
Description
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
ΔVCH/VCH
Output Charge Voltage Tolerance
VMIN
Preconditioning Voltage Threshold
VRCH
Battery Recharge Voltage Threshold
Current Regulation
ICH
Charge Current Programmable Range
ΔICH/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
Conditions
Min
Rising Edge
4.0
3
Typ
150
0.5
0.3
0.4
Charge Current = 200mA
VBAT = 4.25V, EN_BAT = GND
VBAT = 4V, ADP Pin Open
4.158
2.85
Measured from VBAT_EOC
4.20
0.5
3.0
-0.1
15
Max
Units
6.5
4
V
V
mV
mA
µA
µA
1
1
2
4.242
3.15
500
mA
%
V
1.1
Ω
10
2
800
VADP = 5.5V
0.9
1.6
0.4
0.4
8
STAT Pin Sinks 4mA
ICH = 100mA
4.4
10
10
V
%
V
V
V
V
V
mA
V
%
%
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 correlation with statistical process controls.
2557.2007.06.1.0
5
AAT2557
500mA Battery Charger and 300mA
LDO Regulator for Portable Systems
Typical Characteristics – Battery Charger
Charging Current vs. Battery Voltage
Constant Charging Current
vs. Set Resistor Values
(VADP = 5V)
600
1000
RSET = 3.24kΩ
100
ICH (mA)
ICH (mA)
500
10
400
RSET = 5.36kΩ
300
RSET = 8.06kΩ
200
100
1
RSET = 16.2kΩ
RSET = 31.6kΩ
3.1
3.7
0
1
10
100
2.7
1000
2.9
3.3
3.5
3.9
4.1
4.3
VBAT (V)
RSET (kΩ
Ω)
End of Charge Battery Voltage
vs. Supply Voltage
End of Charge Voltage Regulation
vs. Temperature
(RSET = 8.06kΩ
Ω)
4.206
4.23
RSET = 8.06kΩ
4.22
VBAT_EOC (V)
VBAT_EOC (V)
4.204
4.202
4.200
RSET = 31.6kΩ
4.198
4.196
4.194
4.21
4.20
4.19
4.18
4.5
4.75
5
5.25
5.5
5.75
6
6.25
4.17
6.5
-50
-25
Constant Charging Current vs.
Supply Voltage
75
100
210
208
210
205
VBAT = 3.3V
ICH (mA)
ICH (mA)
50
(RSET = 8.06kΩ
Ω)
220
200
190
VBAT = 3.6V
VBAT = 4V
203
200
198
195
180
193
4
4.25
4.5
4.75
5
5.25
5.5
VADP (V)
6
25
Constant Charging Current vs. Temperature
(RSET = 8.06kΩ
Ω)
170
0
Temperature (°C)
VADP (V)
5.75
6
6.25
6.5
190
-50
-25
0
25
50
75
100
Temperature (°C)
2557.2007.06.1.0
AAT2557
500mA Battery Charger and 300mA
LDO Regulator for Portable Systems
Typical Characteristics – Battery Charger
Operating Current vs. Temperature
Preconditioning Threshold Voltage
vs. Temperature
(RSET = 8.06kΩ
Ω)
(RSET = 8.06kΩ
Ω)
550
3.03
3.02
450
VMIN (V)
IOP (µA)
500
400
3.01
3
2.99
350
2.98
300
-50
-25
0
25
50
75
2.97
-50
100
-25
0
Temperature (°C)
Preconditioning Charge Current
vs. Temperature
(RSET = 8.06kΩ
Ω)
ITRICKLE (mA)
ITRICKLE (mA)
20.4
20.2
20.0
19.8
19.6
25
50
75
RSET = 5.36kΩ
30
RSET = 8.06kΩ
20
0
100
4
4.2
4.4
4.6
4.8
5
5.2
5.4
5.6
5.8
6
6.2
6.4
VADP (V)
Recharging Threshold Voltage
vs. Temperature
Sleep Mode Current vs. Supply Voltage
(RSET = 8.06kΩ
Ω)
800
4.18
700
4.16
85°C
600
ISLEEP (nA)
4.14
4.12
4.10
4.08
500
400
300
4.06
200
4.04
100
4.02
RSET = 31.6kΩ
RSET = 16.2kΩ
Temperature (°C)
(RSET = 8.06kΩ
Ω)
VRCH (V)
40
10
19.4
0
100
RSET = 3.24kΩ
50
-25
75
60
20.6
-50
50
Preconditioning Charge Current
vs. Supply Voltage
20.8
19.2
25
Temperature (°C)
-50
-25
0
25
50
Temperature (°C)
2557.2007.06.1.0
75
100
25°C
-40°C
0
4
4.25
4.5
4.75
5
5.25
5.5
5.75
6
6.25
6.5
VADP (V)
7
AAT2557
500mA Battery Charger and 300mA
LDO Regulator for Portable Systems
Typical Characteristics – Battery Charger
VEN(H) vs. Supply Voltage
VEN(L) vs. Supply Voltage
(RSET = 8.06kΩ
Ω)
(RSET = 8.06kΩ
Ω)
1.2
1.1
1
0.9
25°C
0.8
85°C
0.9
0.8
25°C
0.7
85°C
0.6
0.7
4
4.25
4.5
4.75
5
5.25
5.5
VADP (V)
8
-40°C
1
-40°C
VEN(L) (V)
VEN(H) (V)
1.1
5.75
6
6.25
6.5
4
4.25
4.5
4.75
5
5.25
5.5
5.75
6
6.25
6.5
VADP (V)
2557.2007.06.1.0
AAT2557
500mA Battery Charger and 300mA
LDO Regulator for Portable Systems
Typical Characteristics – LDO Regulator
Dropout Voltage vs. Temperature
Dropout Characteristics
3.2
IL = 300mA
480
360
300
IL = 100mA
IL = 150mA
240
180
120
60
IL = 50mA
0
-40 -30 -20 -10 0
IOUT = 0mA
3.0
420
Output Voltage (V)
Dropout Voltage (mV)
540
2.8
IOUT = 300mA
IOUT = 150mA
2.6
2.4
IOUT = 10mA
2.2
2.0
2.7
10 20 30 40 50 60 70 80 90 100 110 120
2.8
2.9
Temperature (°C)
3.1
3.2
3.3
Ground Current vs. Input Voltage
90
500
Ground Current (μA)
450
Dropout Voltage (mV)
3.0
Input Voltage (V)
Dropout Voltage vs. Output Current
400
350
300
85°C
250
200
25°C
150
-40°C
100
80
70
60
IOUT=300mA
50
IOUT=150mA
IOUT=50mA
40
IOUT=0mA
30
IOUT=10mA
20
10
50
0
0
50
100
150
200
250
0
300
2
2.5
3
3.5
4
4.5
5
Input Voltage (V)
Output Current (mA)
Quiescent Current vs. Temperature
Output Voltage vs. Temperature
1.203
100
90
1.202
80
Output Voltage (V)
Quiescent Current (μA)
IOUT = 100mA
IOUT = 50mA
70
60
50
40
30
20
10
0
-40 -30 -20 -10
0
10 20 30 40 50 60 70 80 90 100 110 120
Temperature (°C)
2557.2007.06.1.0
1.201
1.200
1.199
1.198
1.197
1.196
-40 -30 -20 -10
0
10 20
30
40
50 60
70 80
90 100
Temperature (°C)
9
AAT2557
500mA Battery Charger and 300mA
LDO Regulator for Portable Systems
Typical Characteristics – LDO Regulator
LDO Turn-On Time from Enable
LDO Initial Power-Up Response Time
(VIN Present)
3
2
3
1
2
0
1
0
3
Enable Voltage (top) (V)
Input Voltage (top) (V)
4
4
Output Voltage (bottom) (V)
5
Output Voltage (bottom) (V)
6
2
4
1
3
0
2
1
0
Time (50µs/div)
Time (5µs/div)
Turn-Off Response Time
Line Transient Response
3
2
1
0
Input Voltage (top) (V)
0
6
5
VIN
4
3.00
VOUT
2.99
2.98
Time (5µs/div)
Time (100µs/div)
Load Transient Response
2.75
100
0
IOUT
Output Voltage (top) (V)
Output Voltage (top) (V)
2.80
3.0
2.9
2.8
2.7
VOUT
400
300
200
IOUT
100
0
Output Current (bottom) (mA)
VOUT
Time (100µs/div)
10
(VOUT = 2.8V)
Output Current (bottom) (mA)
2.85
Load Transient Response 300mA
(VOUT = 2.8V)
2.90
Output Voltage (bottom) (V)
5
Output Voltage (bottom) (V)
Enable Voltage (top) (V)
(IOUT = 100mA)
Time (10µs/div)
2557.2007.06.1.0
AAT2557
500mA Battery Charger and 300mA
LDO Regulator for Portable Systems
Typical Characteristics – LDO Regulator
Enable Threshold Voltage (V)
VEN(L) and VEN(H) vs. VIN
1.250
1.225
1.200
VEN(H)
1.175
1.150
1.125
VEN(L)
1.100
1.075
1.050
2.5
3.0
3.5
4.0
4.5
5.0
5.5
Input Voltage (V)
2557.2007.06.1.0
11
AAT2557
500mA Battery Charger and 300mA
LDO Regulator for Portable Systems
Functional Block Diagram
Reverse Blocking
BAT
ADP
OverTemperature
Protection
Charge
Control
-
STAT
Constant
Current
+
+
ISET
-
VREF
UVLO
EN_BAT
INLDO
Err.
Amp.
BYP
VREF
OverCurrent
Protection
OUTLDO
ENLDO
Functional Description
The AAT2557 is a high performance power management IC comprised of a lithium-ion/polymer
battery charger and a linear regulator. The linear
regulator is designed for high-speed turn-on, fast
transient response, good power supply ripple
rejection, and low noise.
Battery Charger
The battery charger is designed for single-cell lithium-ion/polymer batteries using a constant current
and constant voltage algorithm. The battery
12
GND
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.
2557.2007.06.1.0
AAT2557
500mA Battery Charger and 300mA
LDO Regulator for Portable Systems
Linear Regulator
Protection Circuitry
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.
Over-Voltage Protection
A battery charger over-voltage protection event is
defined as a condition where the voltage on the
BAT pin exceeds the over-voltage protection
threshold (VOVP) (4.4V). 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.
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 (ENLDO) is active high and is compatible
with CMOS logic. To assure the LDO regulator will
switch on, the ENLDO turn-on control level must be
greater than 1.5V. The LDO regulator will go into
the disable shutdown mode when the voltage on
the ENLDO 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.
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.
2557.2007.06.1.0
Over-Temperature Protection
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 (145°C). Once the internal die
temperature falls below the thermal limit, normal
charging operation will resume.
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 dissipation exceeds the
device thermal limit.
Thermal Protection
The AAT2557’s LDO 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
overtemperature damage. The LDO regulator output
will remain in a shutdown state until the internal die
temperature falls back below the 145°C trip point.
The combination and interaction between the shortcircuit and thermal protection systems allow the
LDO regulator to withstand indefinite short-circuit
conditions without sustaining permanent damage.
13
AAT2557
500mA Battery Charger and 300mA
LDO Regulator for Portable Systems
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.
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.
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.
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
Preconditioning
Trickle Charge
Phase
Constant Current
Charge Phase
Constant Voltage
Charge Phase
Charge Complete Voltage
I = Max CC
Regulated Current
Constant Current Mode
Voltage Threshold
Trickle Charge and
Termination Threshold
I = CC / 10
Figure 1: Current vs. Voltage Profile During Charging Phases.
14
2557.2007.06.1.0
AAT2557
500mA Battery Charger and 300mA
LDO Regulator for Portable Systems
Battery Charging System Operation Flow Chart
Enable
No
Power On Reset
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)
Yes
Constant
Current Charge
Mode
Yes
Constant
Voltage Charge
Mode
No
No
Recharge Test
V RCH > VBAT
Yes
Current Phase Test
V BAT_EOC > VBAT
No
Voltage Phase Test
IBAT > ITERM
No
Charge Completed
2557.2007.06.1.0
15
AAT2557
500mA Battery Charger and 300mA
LDO Regulator for Portable Systems
Application Information
Soft Start / Enable
Normal
ICHARGE (mA)
Set Resistor
Value R1 (kΩ)
500
400
300
250
200
150
100
50
40
30
20
15
3.24
4.12
5.36
6.49
8.06
10.7
16.2
31.6
38.3
53.6
78.7
105
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 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.
The LDO is enabled when the ENLDO pin is pulled
high. The control and feedback circuits have been
optimized for high-speed, monotonic turn-on characteristics.
Table 1: RSET Values.
1000
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.
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
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 15mA to 500mA may be set by selecting
the appropriate resistor value from Table 1.
16
ICH (mA)
Adapter or USB Power Input
100
10
1
1
10
100
1000
RSET (kΩ
Ω)
Figure 2: Constant Charging Current
vs. Set Resistor Values.
Charge Status Output
The AAT2557 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.
2557.2007.06.1.0
AAT2557
500mA Battery Charger and 300mA
LDO Regulator for Portable Systems
Event Description
Status
No battery charging activity
Battery charging via adapter
or USB port
Charging completed
OFF
ON
OFF
Table 2: LED Status Indicator.
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.
First, the maximum power dissipation for a given
situation should be calculated:
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.
Where:
The required ballast resistor values can be estimated using the following formulas:
TA
R 1=
(VADP - VF(LED))
ILED
PD(MAX) =
(TJ(MAX) - TA)
θJA
PD(MAX) = Maximum Power Dissipation (W)
θJA
= Package Thermal Resistance (°C/W)
TJ(MAX) = Maximum Device Junction Temperature
(°C) [135°C]
= Ambient Temperature (°C)
PD = [(VADP - VBAT) · ICH + (VADP · IOP)] + (VINLDO - VOUTLDO) ILDOLOAD + VINLDO · IQLDO
Where:
Example:
R1 =
(5.5V - 2.0V)
= 1.75kΩ
2mA
Note: Red LED forward voltage (VF) is typically
2.0V @ 2mA.
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
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 considerations should be taken into account
when designing the printed circuit board layout, as
well as the placement of the charger IC package in
2557.2007.06.1.0
VOUTLDO = Output Voltage as Seen at the OUTLDO
Pin
ILDOLOAD = LDO Load Current
IQLDO
= LDO Quiescent Current
17
AAT2557
500mA Battery Charger and 300mA
LDO Regulator for Portable Systems
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.
ICH(MAX) =
(PD(MAX) - VIN · IOP)
VIN - VBAT
(TJ(MAX) - TA) - V · I
IN
OP
θJA
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.
Capacitor Selection
Linear Regulator Input Capacitor
An input capacitor greater than 1µF 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
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 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 CIN capacitor in the
range of 10µF should be used. A larger input
capacitor in this application will minimize switching
or power transient effects when the power supply is
"hot plugged" in.
18
Linear Regulator Output Capacitor
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 1.0µF to 10µF range are recommended for best performance. Applications utilizing
the exceptionally low output noise and optimum
power supply ripple rejection should use 2.2µF 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 0.47µF.
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 document 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
2557.2007.06.1.0
AAT2557
500mA Battery Charger and 300mA
LDO Regulator for Portable Systems
turn-off time are desired, the value of CBYP should
be reduced.
Printed Circuit Board Layout
Considerations
In applications where low noise performance
and/or ripple rejection are less of a concern, the
bypass capacitor may be omitted. The fastest
device turn-on time will be realized when no
bypass capacitor is used.
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 possible to ADP and INLDO.
2557.2007.06.1.0
19
AAT2557
500mA Battery Charger and 300mA
LDO Regulator for Portable Systems
Manufacturer
Murata
Murata
Murata
Murata
Murata
Murata
Murata
Murata
Part Number
Value
(µF)
Voltage
Rating
Temp.
Co.
Case
Size
GRM21BR61A106KE19
GRM188R60J475KE19
GRM188R61A225KE34
GRM188R60J225KE19
GRM188R61A105KA61
GRM185R60J105KE26
GRM188F51H103ZA01
GRM155F51H103ZA01
10
4.7
2.2
2.2
1.0
1.0
0.01
0.01
10
6.3
10
6.3
10
6.3
50
50
X5R
X5R
X5R
X5R
X5R
X5R
Y5V
Y5V
0805
0603
0603
0603
0603
0603
0603
0402
Table 3: Surface Mount Capacitors.
20
2557.2007.06.1.0
AAT2557
500mA Battery Charger and 300mA
LDO Regulator for Portable Systems
Ordering Information
Package
Marking1
Part Number (Tape and Reel)2
TSOPJW-14
VKXYY
AAT2557ITO-CT-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
Code
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
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.
2557.2007.06.1.0
21
AAT2557
500mA Battery Charger and 300mA
LDO Regulator for Portable Systems
Package Information
TSOPJW-14
2.85 ± 0.20
2.40 ± 0.10
0.20 BSC
0.40 BSC
Top View
7° NOM
0.04 REF
+ 0.05
0.05 - 0.04
0.15 ± 0.05
+ 0.05
1.05 - 0.00
+ 0.000
1.00 - 0.075
+ 0.05
3.05 - 0.10
4° ± 4°
0.45 ± 0.15
2.75 ± 0.25
All dimensions in millimeters.
© 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
22
2557.2007.06.1.0