AAT2556 [ANALOGICTECH]
Battery Charger and Step-Down Converter for Portable Applications; 电池充电器和降压型转换器，用于便携式应用
| 型号： | AAT2556 |
| 厂家： | 
ADVANCED ANALOGIC TECHNOLOGIES |
| 描述： | Battery Charger and Step-Down Converter for Portable Applications |
| 文件： | 总29页 (文件大小：745K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
AAT2556
Battery Charger and Step-Down
Converter for Portable Applications
™
SystemPower
General Description
Features
The AAT2556 is a member of AnalogicTech's Total
Power Management IC™ (TPMIC™) product fam-
ily. It is a fully integrated 500mA battery charger
plus a 250mA step-down converter. The input volt-
age range is 4V to 6.5V for the battery charger and
2.7V to 5.5V for the step-down converter, making it
ideal for single-cell lithium-ion/polymer battery-
powered applications.
•
Battery Charger:
— Input Voltage Range: 4V to 6.5V
— Programmable Charging Current up to
500mA
— Highly Integrated Battery Charger
— Charging Device
— Reverse Blocking Diode
Step-Down Converter:
•
— Input Voltage Range: 2.7V to 5.5V
— Output Voltage Range: 0.6V to VIN
— 250mA Output Current
— Up to 96% Efficiency
— 30µA Quiescent Current
— 1.5MHz Switching Frequency
— 100µs Start-Up Time
Short-Circuit, Over-Temperature, and Current
Limit Protection
TDFN33-12 Package
The battery charger is a complete constant current/
constant voltage linear charger. It offers an inte-
grated pass device, reverse blocking protection,
high current accuracy and voltage regulation,
charge status, and charge termination. The charg-
ing current is programmable via external resistor
from 15mA to 500mA. In addition to standard fea-
tures, the device offers over-voltage, current limit,
and thermal protection.
•
•
•
The step-down converter is a highly integrated
converter operating at 1.5MHz of switching fre-
quency, minimizing the size of external compo-
nents while keeping switching losses low. It has
independent input and enable pins. The output
voltage ranges from 0.6V to the input voltage. The
feedback and control deliver excellent load regula-
tion and transient response with a small output
inductor and capacitor.
-40°C to +85°C Temperature Range
Applications
•
•
•
•
•
•
Bluetooth™ Headsets
Cellular Phones
Handheld Instruments
MP3 and Portable Music Players
PDAs and Handheld Computers
Portable Media Players
The AAT2556 is available in a Pb-free, thermally-
enhanced TDFN33-12 package and is rated over
the -40°C to +85°C temperature range.
Typical Application
Adapter / USB Input
ADP
VIN
EN_BUCK
BAT
STAT
BATT +
Enable
EN_BAT
VOUT
L= 3.3µH
RFB1
C
LX
FB
BATT -
ISET
COUT
RSET
RFB2
GND
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AAT2556
Battery Charger and Step-Down
Converter for Portable Applications
Pin Descriptions
Pin #
Symbol
Function
1
FB
Feedback input. This pin must be connected directly to an external resistor divider.
Nominal voltage is 0.6V.
2, 8, 10
3
GND
Ground.
EN_BUCK
Enable pin for the step-down converter. When connected to logic low, the step-down
converter is disabled and it consumes less than 1µA of current. When connected to
logic high, it resumes normal operation.
4
5
EN_BAT
ISET
Enable pin for the battery charger. When internally pulled down, the battery charger is
disabled and it consumes less than 1µA of current. When connected to logic high, it
resumes normal operation.
Charge current set point. Connect a resistor from this pin to ground. Refer to typical
curves for resistor selection.
6
7
BAT
STAT
ADP
LX
Battery charging and sensing.
Charge status input. Open drain status input.
9
Input for USB/adapter charger.
11
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.
Input voltage for the step-down converter.
12
VIN
EP
Exposed paddle (bottom): connect to ground directly beneath the package.
Pin Configuration
TDFN33-12
(Top View)
1
2
3
4
5
6
12
11
10
9
FB
GND
EN_BUCK
EN_BAT
ISET
VIN
LX
GND
ADP
GND
STAT
8
7
BAT
2
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AAT2556
Battery Charger and Step-Down
Converter for Portable Applications
Absolute Maximum Ratings1
Symbol
Description
Value
Units
VIN
VADP
VLX
VFB
VEN
VX
Input Voltage to GND
6.0
V
V
Adapter Voltage to GND
-0.3 to 7.5
LX to GND
-0.3 to VIN + 0.3
-0.3 to VIN + 0.3
-0.3 to 6.0
V
FB to GND
V
EN_BAT and EN_BUCK to GND
BAT, ISET and STAT to GND
Operating Junction Temperature Range
Maximum Soldering Temperature (at leads, 10 sec)
V
-0.3 to VADP + 0.3
-40 to 150
V
TJ
°C
°C
TLEAD
300
Thermal Information
Symbol
Description
Value
Units
PD
Maximum Power Dissipation
Thermal Resistance2
2.0
50
W
θJA
°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.
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AAT2556
Battery Charger and Step-Down
Converter for Portable Applications
Electrical Characteristics1
VIN = 3.6V; TA = -40°C to +85°C, unless otherwise noted. Typical values are TA = 25°C.
Symbol
Description
Conditions
Min
Typ
Max Units
Step-Down Converter
VIN
Input Voltage
2.7
5.5
2.7
V
V
VIN Rising
VUVLO
UVLO Threshold
Hysteresis
200
mV
V
VIN Falling
1.8
IOUT = 0 to 250mA,
VIN = 2.7V to 5.5V
-3.0
3.0
VIN
1.0
%
VOUT
Output Voltage Tolerance2
VOUT
IQ
Output Voltage Range
Quiescent Current
0.6
V
µA
µA
mA
Ω
No Load
30
ISHDN
Shutdown Current
EN = GND
ILIM
P-Channel Current Limit
High-Side Switch On Resistance
Low-Side Switch On Resistance
LX Leakage Current
600
0.59
0.42
RDS(ON)H
RDS(ON)L
ILXLEAK
Ω
VIN = 5.5V, VLX = 0 to VIN
VIN = 2.7V to 5.5V
VIN = 3.6V
1.0
µA
%/V
V
ΔVLinereg/ΔVIN Line Regulation
0.2
VFB
Feedback Threshold Voltage Accuracy
0.597 0.606 0.615
IFB
FB Leakage Current
Oscillator Frequency
VOUT = 1.0V
0.2
1.5
µA
MHz
FOSC
From Enable to Output
Regulation
TS
Startup Time
100
µs
TSD
THYS
VEN(L)
VEN(H)
IEN
Over-Temperature Shutdown Threshold
Over-Temperature Shutdown Hysteresis
Enable Threshold Low
140
°C
°C
V
15
0.6
1.0
Enable Threshold High
1.4
-1.0
V
Input Low Current
VIN = VEN = 5.5V
µA
1. The AAT2556 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. Output voltage tolerance is independent of feedback resistor network accuracy.
4
2556.2006.05.1.0
AAT2556
Battery Charger and Step-Down
Converter for Portable Applications
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
3
6.5
4
V
Under-Voltage Lockout (UVLO)
UVLO Hysteresis
Rising Edge
V
VUVLO
150
0.5
0.3
0.4
mV
mA
µA
µA
IOP
Operating Current
Charge Current = 200mA
VBAT = 4.25V, EN = GND
1
1
2
ISHUTDOWN
ILEAKAGE
Voltage Regulation
Shutdown Current
Reverse Leakage Current from BAT Pin VBAT = 4V, ADP Pin Open
VBAT EOC
End of Charge Accuracy
4.158 4.20 4.242
0.5
V
%
V
_
ΔVCH/VCH
VMIN
Output Charge Voltage Tolerance
Preconditioning Voltage Threshold
Battery Recharge Voltage Threshold
2.85
3.0
3.15
VRCH
Measured from VBAT EOC
-0.1
V
_
Current Regulation
ICH
ΔICH/ICH
VSET
Charge Current Programmable Range
15
500
mA
%
Charge Current Regulation Tolerance
ISET Pin Voltage
10
2
V
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(H)
VEN(L)
Input High Threshold
1.6
V
V
Input Low Threshold
0.4
0.4
8
VSTAT
Output Low Voltage
STAT Pin Sinks 4mA
ICH = 100mA
V
ISTAT
STAT Pin Current Sink Capability
Over-Voltage Protection Threshold
Pre-Charge Current
mA
V
VOVP
4.4
10
10
ITK/ICHG
TERM/ICHG
%
%
I
Charge Termination Threshold Current
1. The AAT2556 output charge voltage is specified over the 0° to 70°C ambient temperature range; operation over the -25°C to +85°C
temperature range is guaranteed by design.
2556.2006.05.1.0
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AAT2556
Battery Charger and Step-Down
Converter for Portable Applications
Typical Characteristics – Step-Down Converter
Efficiency vs. Load
(VOUT = 1.8V; L = 3.3µH)
DC Load Regulation
(VOUT = 1.8V; L = 3.3µH)
100
90
80
70
60
50
40
1.0
0.5
VIN = 5.0V
VIN = 2.7V
VIN = 3.6V
VIN = 3.6V
VIN = 5.5V
VIN = 5.5V
0.0
VIN = 2.7V
VIN = 4.2V
VIN = 5.0V
VIN = 4.2V
-0.5
-1.0
0.1
1
10
100
1000
0.1
1
10
100
1000
Output Current (mA)
Output Current (mA)
Efficiency vs. Load
(VOUT = 1.2V; L = 1.5µH)
DC Load Regulation
(VOUT = 1.2V; L = 1.5µH)
100
90
80
70
60
50
40
30
1.0
0.5
VIN = 2.7V
VIN = 5.0V
VIN = 3.6V
VIN = 5.5V
0.0
VIN = 5.5V
VIN = 5.0V
VIN = 4.2V
VIN = 3.6V
VIN = 4.2V
-0.5
-1.0
VIN = 2.7V
0.1
1
10
100
1000
0.1
1
10
100
1000
Output Current (mA)
Output Current (mA)
Soft Start
(VIN = 3.6V; VOUT = 1.8V;
OUT = 250mA; CFF = 100pF)
Line Regulation
(VOUT = 1.8V)
I
0.6
5.0
4.0
3.0
2.0
1.0
0.0
1.6
1.4
1.2
1.0
0.8
0.6
0.4
0.2
0.0
-0.2
-0.4
0.5
0.4
VEN
IOUT = 0mA
IOUT = 50mA
0.3
0.2
IOUT = 150mA
0.1
-1.0
-2.0
-3.0
-4.0
-5.0
VO
0.0
-0.1
-0.2
-0.3
IOUT = 10mA
IOUT = 250mA
IL
2.5
3.0
3.5
4.0
4.5
5.0
5.5
6.0
Time (100µs/div)
Input Voltage (V)
6
2556.2006.05.1.0
AAT2556
Battery Charger and Step-Down
Converter for Portable Applications
Typical Characteristics – Step-Down Converter
Output Voltage Error vs. Temperature
(VIN = 3.6V; VOUT = 1.8V; IOUT = 250mA)
Switching Frequency Variation
vs. Temperature
(VIN = 3.6V; VOUT = 1.8V)
3.0
2.0
10.0
8.0
6.0
1.0
4.0
2.0
0.0
0.0
-2.0
-4.0
-6.0
-8.0
-10.0
-1.0
-2.0
-3.0
-40
-20
0
20
40
60
80
100
5.5
6.0
-40
-20
0
20
40
60
80
100
Temperature (°C)
Temperature (°C)
Frequency Variation vs. Input Voltage
(VOUT = 1.8V)
No Load Quiescent Current vs. Input Voltage
50
45
40
2.0
1.0
0.0
85°C
35
-1.0
-2.0
-3.0
-4.0
30
25°C
25
-40°C
20
15
10
2.7
3.1
3.5
3.9
4.3
4.7
5.1
2.7
3.1
3.5
3.9
4.3
4.7
5.1
5.5
Input Voltage (V)
Input Voltage (V)
P-Channel RDS(ON) vs. Input Voltage
N-Channel RDS(ON) vs. Input Voltage
750
1000
900
800
700
600
500
400
300
700
650
600
550
500
450
400
350
300
120°C 100°C
85°C
120°C
100°C
85°C
25°C
25°C
2.5
3.0
3.5
4.0
4.5
5.0
5.5
2.5
3.0
3.5
4.0
4.5
5.0
5.5
6.0
Input Voltage (V)
Input Voltage (V)
2556.2006.05.1.0
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AAT2556
Battery Charger and Step-Down
Converter for Portable Applications
Typical Characteristics – Step-Down Converter
Load Transient Response
(10mA to 250mA; VIN = 3.6V; VOUT = 1.8V;
Load Transient Response
(10mA to 250mA; VIN = 3.6V; VOUT = 1.8V; COUT = 4.7µF)
C
OUT = 4.7µF; CFF = 100pF)
2.0
1.9
1.8
1.7
1.6
1.5
1.4
1.3
1.2
2.0
1.9
1.8
1.7
1.6
1.5
1.4
1.3
1.2
1.4
1.2
1.0
0.8
0.6
0.4
0.2
0.0
-0.2
VO
VO
IO
IO
ILX
ILX
Time (25µs/div)
Time (25µs/div)
Line Response
(VOUT = 1.8V @ 250mA; CFF = 100pF)
Output Ripple
(VIN = 3.6V; VOUT = 1.8V; IOUT = 1mA)
40
20
0.07
0.06
0.05
0.04
0.03
0.02
0.01
0.00
-0.01
1.90
1.85
1.80
1.75
1.70
1.65
1.60
1.55
1.50
7.0
6.5
6.0
5.5
5.0
4.5
4.0
3.5
3.0
VO
VO
0
-20
-40
-60
-80
-100
-120
VIN
IL
Time (25µs/div)
Time (2µs/div)
Output Ripple
(VIN = 3.6V; VOUT = 1.8V; IOUT = 250mA)
40
20
0.8
0.7
0.6
0.5
0.4
0.3
0.2
0.1
0.0
VO
0
-20
-40
-60
-80
-100
-120
IL
Time (200ns/div)
8
2556.2006.05.1.0
AAT2556
Battery Charger and Step-Down
Converter for Portable Applications
Typical Characteristics – Battery Charger
Constant Charging Current
vs. Set Resistor Values
Charging Current vs. Battery Voltage
(VADP = 5V)
600
500
400
300
200
100
0
1000
100
10
RSET = 3.24kΩ
RSET = 5.62kΩ
RSET = 8.06kΩ
RSET = 31.6kΩ
RSET = 16.2kΩ
1
2.7
2.9
3.1
3.3
3.5
3.7
3.9
4.1
4.3
1
10
100
1000
VBAT (V)
RSET (kΩ)
End of Charge Battery Voltage
vs. Supply Voltage
End of Charge Voltage Regulation
vs. Temperature
(RSET = 8.06kΩ)
4.206
4.204
4.202
4.200
4.198
4.196
4.194
4.23
4.22
4.21
4.20
4.19
4.18
4.17
RSET = 8.06kΩ
RSET = 31.6kΩ
4.5
4.75
5
5.25
5.5
5.75
6
6.25
6.5
-50
-25
0
25
50
75
100
VADP (V)
Temperature (°C)
Constant Charging Current vs.
Supply Voltage
Constant Charging Current vs. Temperature
(RSET = 8.06kΩ)
(RSET = 8.06kΩ)
210
208
205
203
200
198
195
193
190
220
210
200
190
180
VBAT = 3.3V
VBAT = 4V
VBAT = 3.6V
170
4
-50
-25
0
25
50
75
100
4.25 4.5 4.75
5
5.25 5.5 5.75
6
6.25 6.5
VADP
(V)
Temperature (°C)
2556.2006.05.1.0
9
AAT2556
Battery Charger and Step-Down
Converter for Portable Applications
Typical Characteristics – Battery Charger
Operating Current vs. Temperature
(RSET = 8.06kΩΩ)
Preconditioning Threshold Voltage
vs. Temperature
(RSET = 8.06kΩ)
550
500
450
400
350
300
3.03
3.02
3.01
3
2.99
2.98
2.97
-50
-25
0
25
50
75
100
-50
-25
0
25
50
75
100
Temperature (°C)
Temperature (°C)
Preconditioning Charge Current
vs. Temperature
Preconditioning Charge Current
vs. Supply Voltage
(RSET = 8.06kΩΩ)
60
20.8
20.6
20.4
20.2
20.0
19.8
19.6
19.4
19.2
RSET = 3.24kΩ
50
40
30
20
10
0
RSET = 5.62kΩ
RSET = 8.06kΩ
RSET = 31.6kΩ
RSET = 16.2kΩ
4
4.2 4.4 4.6 4.8
5
5.2 5.4 5.6 5.8
6
6.2 6.4
-50
-25
0
25
50
75
100
Temperature (°C)
VADP (V)
Recharging Threshold Voltage
vs. Temperature
Sleep Mode Current vs. Supply Voltage
(RSET = 8.06kΩ)
(RSET = 8.06kΩΩ)
800
700
600
500
400
300
200
100
0
4.18
4.16
4.14
4.12
4.10
4.08
4.06
4.04
4.02
85°C
25°C
-40°C
-50
-25
0
25
50
75
100
4
4.25 4.5 4.75
5
5.25 5.5 5.75
6
6.25 6.5
Temperature (°C)
VADP (V)
10
2556.2006.05.1.0
AAT2556
Battery Charger and Step-Down
Converter for Portable Applications
Typical Characteristics – Battery Charger
VEN(H) vs. Supply Voltage
(RSET = 8.06kΩΩ)
VEN(L) vs. Supply Voltage
(RSET = 8.06kΩ)
1.2
1.1
1
1.1
1
-40°C
-40°C
0.9
0.8
0.7
0.6
0.9
0.8
0.7
25°C
85°C
25°C
85°C
4
4.25 4.5 4.75
5
5.25 5.5 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)
VADP (V)
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AAT2556
Battery Charger and Step-Down
Converter for Portable Applications
Functional Block Diagram
Reverse Blocking
BAT
ADP
-
+
Constant
Current
Charge
Control
ISET
VREF
Over-
Temperature
Protection
STAT
UVLO
T
EN_BA
VIN
FB
DH
DL
-
+
LX
Logic
VREF
Input
EN_BUCK
GND
state are fully monitored for fault conditions. In the
event of an over-voltage or over-temperature fail-
ure, the device will automatically shut down, pro-
tecting the charging device, control system, and
the battery under charge. Other features include
an integrated reverse blocking diode and sense
resistor.
Functional Description
The AAT2556 is a high performance power system
comprised of a 500mA lithium-ion/polymer battery
charger and a 250mA step-down converter.
The battery charger is designed for single-cell
lithium-ion/polymer batteries using a constant cur-
rent and constant voltage algorithm. The battery
charger operates from the adapter/USB input volt-
age 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 bat-
tery charge state by directly driving one external
LED. Internal device temperature and charging
The step-down converter operates with an input volt-
age 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 30µA of current, making it ideal
for battery-operated applications. The output volt-
age is programmable from VIN to as low as 0.6V.
12
2556.2006.05.1.0
AAT2556
Battery Charger and Step-Down
Converter for Portable Applications
Power devices are sized for 250mA current capabil-
ity while maintaining over 90% 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.
mal limit threshold. Once the internal die tempera-
ture falls below the thermal limit, normal charging
operation will resume.
Control Loop
The AAT2556 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-pro-
grammed current source in parallel with the output
capacitor. The output of the voltage error amplifier
programs the current mode loop for the necessary
peak switch current to force a constant output volt-
age 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.
Under-Voltage Lockout
The AAT2556 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 con-
trol 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
Battery Charging Operation
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.
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 (internal-
ly 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 charg-
ing 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 MOS-
FET when the input-output voltage differential is at
its highest.
Current Limit, Over-Temperature Protection
For overload conditions, the peak input current is
limited at the step-down converter. As load imped-
ance 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 dis-
ables 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 ther-
2556.2006.05.1.0
13
AAT2556
Battery Charger and Step-Down
Converter for Portable Applications
Preconditioning
Trickle Charge
Phase
Constant Current
Charge Phase
Constant Voltage
Charge Phase
Charge Complete Voltage
Regulated Current
I = Max CC
Constant Current Mode
Voltage Threshold
Trickle Charge and
I = CC / 10
Termination Threshold
Figure 1: Current vs. Voltage Profile During Charging Phases.
Pre-conditioning continues until the battery voltage
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 direc-
tions, preventing the battery from discharging
through the IC.
reaches VMIN. At this point, the charger begins con-
stant-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 regu-
lation point, VBAT. When the battery voltage reach-
es VBAT, the battery charger begins constant volt-
age mode. The regulation voltage is factory pro-
grammed to a nominal 4.2V (±0.5%) and will con-
tinue charging until the charging current has
reduced to 10% of the programmed current.
The battery charger will remain in sleep mode,
even if the charger source is disconnected, until
one of the following events occurs: the battery ter-
minal voltage drops below the VRCH threshold; the
charger EN pin is recycled; or the charging source
is reconnected. In all cases, the charger will mon-
itor all parameters and resume charging in the
most appropriate mode.
14
2556.2006.05.1.0
AAT2556
Battery Charger and Step-Down
Converter for Portable Applications
Battery Charging System Operation Flow Chart
Enable
Yes
Power On Reset
No
Power Input
Voltage
VADP > VUVLO
Yes
Fault Conditions
Monitoring
OV, OT
Charge
Control
Shut Down
Yes
No
Preconditioning
Test
VMIN > VBAT
Preconditioning
(Trickle Charge)
Yes
No
No
Constant
Current Charge
Mode
Recharge Test
VRCH > VBAT
Current Phase Test
Yes
Yes
V
ADP > VBAT
No
Constant
Voltage Charge
Mode
Voltage Phase Test
IBAT > ITERM
Yes
No
Charge Completed
2556.2006.05.1.0
15
AAT2556
Battery Charger and Step-Down
Converter for Portable Applications
Application Information
Normal
Set Resistor
Ω
ICHARGE (mA)
Value R2 (k )
Soft Start / Enable
500
400
300
250
200
150
100
50
3.24
4.12
5.62
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 regard-
less of the battery voltage or charging state. When
it is re-enabled, the charge control circuit will auto-
matically reset and resume charging functions with
the appropriate charging mode based on the bat-
tery charge state and measured cell voltage from
the BAT pin.
40
30
20
15
The step-down converter features a soft start that
limits the inrush current and eliminates output volt-
age overshoot during startup. The circuit is
designed to increase the inductor current limit in
discrete steps when the input voltage or enable
input is applied. Typical start up time is 100µs.
Table 1: RSET Values.
1000
100
10
Pulling EN_BUCK to logic low forces the converter
in a low power, non-switching state, and it con-
sumes less than 1µA of quiescent current.
Connecting it to logic high enables the converter
and resumes normal operation.
1
1
10
100
1000
Adapter or USB Power Input
RSET (kΩ)
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 cur-
rent 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.
Figure 2: Constant Charging Current
vs. Set Resistor Values.
Charge Status Output
The AAT2556 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 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
the fast charge, as well as the preconditioning trick-
le charge current, is dominated by the tolerance of
the set resistor used. For this reason, a 1% toler-
ance metal film resistor is recommended for the set
resistor function. Fast charge constant current lev-
els from 15mA to 500mA may be set by selecting
the appropriate resistor value from Table 1.
Event Description
Status
No battery charging activity
Battery charging via adapter
or USB port
OFF
ON
Charging completed
OFF
Table 2: LED Status Indicator.
16
2556.2006.05.1.0
AAT2556
Battery Charger and Step-Down
Converter for Portable Applications
The LED should be biased with as little current as
necessary to create reasonable illumination; there-
fore, 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:
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)
Figure 3 shows the relationship of maximum
power dissipation and ambient temperature of the
AAT2556.
The required ballast resistor values can be esti-
mated using the following formulas:
3000
2500
2000
1500
1000
500
(VADP
- VF(LED)
ILED
)
R1=
Example:
0
(5.5V - 2.0V)
2mA
0
20
40
60
80
100
120
R1 =
= 1.75kΩ
TA (°C)
Note: Red LED forward voltage (VF) is typically
2.0V @ 2mA.
Figure 3: Maximum Power Dissipation.
Next, the power dissipation of the battery charger
can be calculated by the following equation:
Thermal Considerations
The AAT2556 is offered in a TDFN33-12 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 50°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
proximity to other heat generating devices in a
given application design. The ambient temperature
around the IC will also have an effect on the ther-
mal limits of a battery charging application. The
maximum limits that can be expected for a given
ambient condition can be estimated by the follow-
ing discussion.
PD = [(VADP - VBAT) · ICH + (VADP · IOP)]
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]
First, the maximum power dissipation for a given
situation should be calculated:
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.
(TJ(MAX) - TA)
θJA
PD(MAX)
=
2556.2006.05.1.0
17
AAT2556
Battery Charger and Step-Down
Converter for Portable Applications
IQ is the step-down converter quiescent current.
The term tsw is used to estimate the full load step-
down converter switching losses.
(PD(MAX)
-
VIN
VIN - VBAT
· IOP)
ICH(MAX)
=
(TJ(MAX)
θJA
VIN - VBAT
- TA)
-
VIN · IOP
For the condition where the step-down converter is
in dropout at 100% duty cycle, the total device dis-
sipation reduces to:
ICH(MAX)
=
In general, the worst condition is the greatest volt-
age drop across the IC, when battery voltage is
charged up to the preconditioning voltage thresh-
old. Figure 4 shows the maximum charge current in
different ambient temperatures.
PTOTAL = IO2 · RDSON(H) + IQ · VIN
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.
500
Given the total losses, the maximum junction tem-
perature can be derived from the θJA for the
TDFN33-12 package which is 50°C/W.
400
TA = 60°C
300
TA = 85°C
200
TJ(MAX)
=
PTOTAL
·
Θ
JA + TAMB
100
0
4.25 4.5 4.75
5
5.25 5.5 5.75
6
6.25 6.5 6.75
VIN (V)
Capacitor Selection
Battery Charger Input Capacitor (C1)
Figure 4: Maximum Charging Current Before
Thermal Cycling Becomes Active.
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.
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) characteris-
tics 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])
PTOTAL
=
VIN
Step-Down Converter Input Capacitor (C3)
Select a 4.7µF to 10µF X7R or X5R ceramic capac-
itor for the input. To estimate the required input
capacitor size, determine the acceptable input rip-
ple level (VPP) and solve for CIN. The calculated
value varies with input voltage and is a maximum
when VIN is double the output voltage.
+ (tsw · FS · IO + IQ) · VIN
18
2556.2006.05.1.0
AAT2556
Battery Charger and Step-Down
Converter for Portable Applications
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.
VO
VIN
⎛
· 1
⎝
VO
VIN
⎞
⎠
-
CIN =
⎛
⎝
VPP
IO
⎞
- ESR
·
FS
⎠
The proper placement of the input capacitor (C3)
can be seen in the evaluation board layout in
Figure 6.
VO
VIN
⎛
· 1
⎝
VO
VIN
⎞
⎠
1
4
-
=
for VIN = 2 · VO
1
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 induc-
tance of these wires, along with the low-ESR
ceramic input capacitor, can create a high Q net-
work 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 meas-
urements can also result.
CIN(MIN)
=
⎛
⎝
VPP
IO
⎞
⎠
- ESR
·
4
·
FS
Always examine the ceramic capacitor DC voltage
coefficient characteristics when selecting the prop-
er value. For example, the capacitance of a 10µF,
6.3V, X5R ceramic capacitor with 5.0V DC applied
is actually about 6µF.
The maximum input capacitor RMS current is:
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.
VO
VIN
⎛
· 1
⎝
VO
VIN
⎞
⎠
IRMS = IO
·
-
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 net-
work and stabilizes the system.
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
VIN
⎛
· 1
⎝
VO
VIN
⎞
⎠
1
2
-
=
D
· (1 - D) = 0.52 =
Battery Charger Output Capacitor (C2)
The AAT2556 only requires a 1µF ceramic capaci-
tor 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 AAT2556 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.
for VIN = 2 · VO
IO
IRMS(MAX)
=
2
VO
·
VIN
⎛
⎝
VO
VIN
⎞
⎠
1
-
The term
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.
Step-Down Converter Output Capacitor (C4)
The output capacitor limits the output ripple and
provides holdup during large load transitions. A
4.7µF to 10µF X5R or X7R ceramic capacitor typi-
cally provides sufficient bulk capacitance to stabi-
lize the output during large load transitions and has
the ESR and ESL characteristics necessary for low
output ripple. For enhanced transient response and
The input capacitor provides a low impedance loop
for the edges of pulsed current drawn by the step-
down converter. Low ESR/ESL X7R and X5R
2556.2006.05.1.0
19
AAT2556
Battery Charger and Step-Down
Converter for Portable Applications
low temperature operation applications, a 10µF
(X5R, X7R) ceramic capacitor is recommended to
stabilize extreme pulsed load conditions.
current down slope meets the internal slope com-
pensation requirements. The internal slope com-
pensation for the AAT2556 is 0.45A/µsec. This
equates to a slope compensation that is 75% of the
inductor current down slope for a 1.8V output and
3.0µH inductor.
The output voltage droop due to a load transient is
dominated by the capacitance of the ceramic out-
put capacitor. During a step increase in load cur-
rent, 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 volt-
age droop during the three switching cycles to the
output capacitance can be estimated by:
0.75 ⋅ VO 0.75 ⋅ 1.8V
= 0.45
A
µsec
m =
=
L
3.0µH
0.75 ⋅ VO
0.75
⋅
VO
A
µsec
A
L =
=
≈
1.67
⋅ VO
m
0.45A
µsec
3
·
VDROOP FS
ΔILOAD
COUT
=
For most designs, the step-down converter operates
with an inductor value of 1µH to 4.7µH. Table 3 dis-
plays inductor values for the AAT2556 with different
output voltage options.
·
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.
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 loss-
es 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 internal voltage loop compensation also limits
the minimum output capacitor value to 4.7µF. 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:
The 3.0µH CDRH2D09 series inductor selected
from Sumida has a 150mΩ 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.
1
VOUT · (VIN(MAX) - VOUT)
IRMS(MAX)
=
·
L · FS · VIN(MAX)
2 · 3
Output Voltage (V)
L1 (µH)
Dissipation due to the RMS current in the ceram-
ic output capacitor ESR is typically minimal,
resulting in less than a few degrees rise in hot-
spot temperature.
1.0
1.2
1.5
1.8
2.5
3.0
3.3
1.5
2.2
2.7
3.0/3.3
3.9/4.2
4.7
Inductor Selection
The step-down converter uses peak current mode
control with slope compensation to maintain stabil-
ity for duty cycles greater than 50%. The output
inductor value must be selected so the inductor
5.6
Table 3: Inductor Values.
20
2556.2006.05.1.0
AAT2556
Battery Charger and Step-Down
Converter for Portable Applications
Adjustable Output Resistor Selection
Ω
Ω
R4 = 221k
R4 = 59k
Resistors R3 and R4 of Figure 5 program the out-
put to regulate at a voltage higher than 0.6V. To
limit the bias current required for the external feed-
back resistor string while maintaining good noise
immunity, the suggested value for R4 is 59kΩ.
Decreased resistor values are necessary to main-
tain noise immunity on the FB pin, resulting in
increased quiescent current. Table 4 summarizes
the resistor values for various output voltages.
Ω
Ω
VOUT (V)
R3 (k )
R3 (k )
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
19.6
29.4
39.2
49.9
59.0
68.1
78.7
88.7
118
75
113
150
187
221
261
301
332
442
464
523
715
1000
V
V
3.3V
0.6V
⎛
⎝
⎞
⎛
⎝
⎞
- 1 ·
R3 =
OUT -1
·
R4 =
59kΩ = 267kΩ
124
137
187
267
⎠
⎠
REF
With enhanced transient response for extreme
pulsed load application, an external feed-forward
capacitor (C5 in Figure 5) can be added.
Table 4: Adjustable Resistor Values For
Step-Down Converter.
JP4
1
2 3
Buck Input
C3
BAT
ADP
VIN
R4
59k
R3
118k
VOUT
4.7µF
L1
3.3µH
C4
C5
100pF
U1
4.7µF
1
12
11
10
9
FB
GND
VIN
2
3
4
5
6
LX
GND
ADP
EN_BUCK
EN_BAT
ISET
8
GND
STAT
C1
10µF
7
BAT
JP1
0Ω
C2
R2
AAT2556
D1
R1
1K
2.2µF
8.06K
RED LED
1
2
3
1
2
JP3
Enable_Bat
Enable_Buck
JP2
Figure 5: AAT2556 Evaluation Board Schematic.
2556.2006.05.1.0
21
AAT2556
Battery Charger and Step-Down
Converter for Portable Applications
3. The feedback pin (Pin 1) 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 regula-
tion. Feedback resistors should be placed as
closely as possible to the FB pin (Pin 1) to mini-
mize 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 the load return
to PGND (Pin 10) and GND (Pin 2) 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.
Printed Circuit Board Layout
Considerations
For the best results, it is recommended to physi-
cally place the battery pack as close as possible to
the AAT2556 BAT pin. To minimize voltage drops
on the PCB, keep the high current carrying traces
adequately wide. Refer to the AAT2556 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, C3) should connect
as closely as possible to ADP (Pin 9) and VIN
(Pin 12).
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.
5. A high density, small footprint layout can be
achieved using an inexpensive, miniature, non-
shielded, high DCR inductor.
Figure 6: AAT2556 Evaluation Board
Top Side Layout.
Figure 7: AAT2556 Evaluation Board
Bottom Side Layout.
22
2556.2006.05.1.0
AAT2556
Battery Charger and Step-Down
Converter for Portable Applications
Component Part Number
Description
Manufacturer
U1
AAT2556IWP-T1
Battery Charger and Step-Down Converter
for Portable Applications; TDFN33-12 Package
CER 10µF 10V 20% X5R 0603
AnalogicTech
C1
C2
ECJ-1VB0J106M
Panasonic - ECG
Murata
GRM185B30J225KE25D CER 2.2µF 6.3V 10% X7R 0603
GRM188R60J475KE19B CER 4.7µF 6.3V 10% X7R 0603
GRM1886R1H101JZ01J CER 100pF 50V 5% R2H 0603
C3, C4
C5
Murata
Murata
L1
CDRH2D09-3R0
Chip Resistor
Chip Resistor
Chip Resistor
Chip Resistor
Chip Resistor
Shielded SMD, 3.0µH, 150mΩ, 3x3x1mm
1KΩ, 5%, 1/4W; 0603
8.06KΩ, 1%, 1/4W; 0603
118KΩ, 1%, 1/4W; 0603
59KΩ, 1%, 1/4W; 0603
0Ω, 5%, 1/4W; 0603
Sumida
R1
Vishay
R2
Vishay
R3
Vishay
R4
Vishay
JP1
Vishay
JP2, JP3, JP4 PRPN401PAEN
Connecting Header, 2mm Zip
Sullins Electronics
Chicago Miniature Lamp
D1
CMD15-21SRC/TR8
Red LED; 1206
Table 5: AAT2556 Evaluation Board Component Listing.
2556.2006.05.1.0
23
AAT2556
Battery Charger and Step-Down
Converter for Portable Applications
Step-Down Converter Design Example
Specifications
VO
VIN
FS
= 1.8V @ 250mA, Pulsed Load ΔILOAD = 200mA
= 2.7V to 4.2V (3.6V nominal)
= 1.5MHz
TAMB = 85°C
1.8V Output Inductor
µsec
µsec
⋅ 1.8V = 3µH
A
L1 = 1.67
⋅ VO2 = 1.67
(use 3.0µH; see Table 3)
A
For Sumida inductor CDRH2D09-3R0, 3.0µH, DCR = 150mΩ.
⎛
⎞
⎠
VO
L1 ⋅ FS
VO
VIN
1.8
V
1.8V
4.2V
⎛
⎞
⎠
ΔIL1 =
⋅ 1 -
⎝
=
⋅ 1 -
= 228mA
⎝
3.0µH ⋅ 1.5MHz
ΔIL1
2
IPKL1 = IO +
= 250mA + 114mA = 364mA
2
PL1 = IO ⋅ DCR = 250mA2 ⋅ 150mΩ = 9.375mW
1.8V Output Capacitor
VDROOP = 0.1V
3 · ΔILOAD
VDROOP · FS
3 · 0.2A
COUT
=
=
= 4µF; use 4.7µF
0.1V · 1.5MHz
(VO) · (VIN(MAX) - VO)
L1 · FS · VIN(MAX)
1
1.8V · (4.2V - 1.8V)
1
·
= 66mArms
IRMS
=
·
=
3.0µH · 1.5MHz · 4.2V
2· 3
2· 3
Pesr = esr · IRMS2 = 5mΩ · (66mA)2 = 21.8µW
24
2556.2006.05.1.0
AAT2556
Battery Charger and Step-Down
Converter for Portable Applications
Input Capacitor
Input Ripple VPP = 25mV
1
1
CIN =
=
= 1.38µF; use 4.7µF
⎛
⎝
VPP
IO
⎞
⎛
⎝
25mV
0.2A
⎞
- ESR
·
4
·
FS
- 5mΩ
·
4
·
1.5MHz
⎠
⎠
IO
IRMS
=
= 0.1Arms
2
P = esr
·
IRMS2 = 5mΩ
·
(0.1A)2 = 0.05mW
AAT2556 Losses
IO2 · (RDSON(H) · VO + RDSON(L) · [VIN -VO
])
PTOTAL
=
VIN
+ (tsw · FS · IO + IQ) · VIN
0.22 · (0.7
Ω
·
1.8V + 0.7Ω
4.2V
· [4.2V - 1.8V])
=
+ (5ns · 1.5MHz · 0.2A + 30µA) · 4.2V = 34.5mW
TJ(MAX) = TAMB + ΘJA · PLOSS = 85°C + (50°C/W) · 34.5mW = 86.7°C
2556.2006.05.1.0
25
AAT2556
Battery Charger and Step-Down
Converter for Portable Applications
1
Ω
Ω
Output Voltage
VOUT (V)
R4 = 59k
R4 = 221k
Ω
Ω
R3 (k )
R3 (k )
L1 (µH)
0.62
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
—
—
75
1.5
1.5
19.6
29.4
39.2
49.9
59.0
68.1
78.7
88.7
118
113
150
187
221
261
301
332
442
464
523
715
1000
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
5.6
124
137
187
267
Table 6: Step-Down Converter Component Values.
Inductance
(µH)
Max DC
Current (mA)
DCR
(mΩ)
Size (mm)
LxWxH
Manufacturer
Part Number
Type
Sumida
Sumida
Sumida
Sumida
Sumida
Sumida
Sumida
Sumida
Sumida
Sumida
Sumida
Taiyo Yuden
Taiyo Yuden
Taiyo Yuden
Taiyo Yuden
FDK
CDRH2D09-1R5
CDRH2D09-2R2
CDRH2D09-2R5
CDRH2D09-3R0
CDRH2D09-3R9
CDRH2D09-4R7
CDRH2D09-5R6
CDRH2D11-1R5
CDRH2D11-2R2
CDRH2D11-3R3
CDRH2D11-4R7
NR3010
1.5
2.2
2.5
3
730
600
530
470
450
410
370
900
780
600
500
1200
1100
870
750
1200
1100
1000
900
88
115
135
150
180
230
260
54
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
Shielded
Shielded
Shielded
Shielded
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
Shielded
Shielded
Shielded
Shielded
78
Shielded
98
Shielded
135
80
Shielded
Shielded
NR3010
95
Shielded
NR3010
140
190
90
Shielded
NR3010
Shielded
MIPWT3226D-1R5
MIPWT3226D-2R2
MIPWT3226D-3R0
MIPWT3226D-4R2
Chip shielded
Chip shielded
Chip shielded
Chip shielded
FDK
100
120
140
FDK
FDK
4.2
Table 7: Suggested Inductors and Suppliers.
1. For reduced quiescent current, R4 = 221kΩ.
2. R4 is opened, R3 is shorted.
26
2556.2006.05.1.0
AAT2556
Battery Charger and Step-Down
Converter for Portable Applications
Value
(µF)
Voltage
Rating
Temp.
Co.
Case
Size
Manufacturer
Part Number
Murata
Murata
GRM118R60J475KE19B
GRM188R60J106ME47D
4.7
10
6.3
6.3
X5R
X5R
0603
0603
Table 8: Surface Mount Capacitors.
2556.2006.05.1.0
27
AAT2556
Battery Charger and Step-Down
Converter for Portable Applications
Ordering Information
Package
Marking1
Part Number (Tape and Reel)2
AAT2556IWP-CA-T1
TDFN33-12
SPXYY
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
Adjustable
(0.6V)
0.9
A
B
E
G
I
1.2
1.5
1.8
1.9
Y
N
O
P
Q
R
S
T
2.5
2.6
2.7
2.8
2.85
2.9
3.0
3.3
W
C
4.2
1. XYY = assembly and date code.
2. Sample stock is generally held on part numbers listed in BOLD.
28
2556.2006.05.1.0
AAT2556
Battery Charger and Step-Down
Converter for Portable Applications
Package Information
TDFN33-12
Index Area
(D/2 x E/2)
Detail "B"
0.3 0.10 0.16 0.375 0.125
0.075 0.075
0.1 REF
3.00 0.05
Detail "A"
1.70 0.05
Top View
Bottom View
Pin 1 Indicator
(optional)
7.5° 7.5°
Detail "B"
Option A:
Option B:
C0.30 (4x) max
Chamfered corner
R0.30 (4x) max
Round corner
0.05 0.05
Detail "A"
Side View
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.
Customers are advised to obtain the latest version of relevant information to verify, before placing orders, that information being relied on is current and complete. All products are sold sub-
ject to the terms and conditions of sale supplied at the time of order acknowledgement, including those pertaining to warranty, patent infringement, and limitation of liability. AnalogicTech
warrants performance of its semiconductor products to the specifications applicable at the time of sale in accordance with AnalogicTech’s standard warranty. Testing and other quality con-
trol 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 regis-
tered trademarks or trademarks of their respective holders.
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830 E. Arques Avenue, Sunnyvale, CA 94085
Phone (408) 737-4600
Fax (408) 737-4611
2556.2006.05.1.0
29
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