AAT AAT2556 Battery charger and step-down converter for portable application Datasheet

AAT2556
Battery Charger and Step-Down
Converter for Portable Applications
General Description
Features
The AAT2556 is a member of AnalogicTech's Total
Power Management IC™ (TPMIC™) product family. It is a fully integrated 500mA battery charger
plus a 250mA step-down converter. The input voltage 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 batterypowered applications.
•
•
The battery charger is a complete constant current/
constant voltage linear charger. It offers an integrated pass device, reverse blocking protection,
high current accuracy and voltage regulation,
charge status, and charge termination. The charging current is programmable via external resistor
from 15mA to 500mA. In addition to standard features, 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 frequency, minimizing the size of external components 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 regulation and transient response with a small output
inductor and capacitor.
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
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
-40°C to +85°C Temperature Range
Applications
•
•
•
•
•
•
The AAT2556 is available in a Pb-free, thermallyenhanced TDFN33-12 package and is rated over
the -40°C to +85°C temperature range.
Bluetooth™ Headsets
Cellular Phones
Handheld Instruments
MP3 and Portable Music Players
PDAs and Handheld Computers
Portable Media Players
Typical Application
Adapter / USB Input
VIN
ADP
EN_BUCK
STAT
BATT +
VOUT
BAT
EN_BAT
L= 3.3µH
C
LX
RFB2
2556.2006.09.1.2
BATT -
ISET
FB
RSET
GND
Battery Pack
RFB1
COUT
System
Enable
1
AAT2556
Battery Charger and Step-Down
Converter for Portable Applications
Pin Descriptions
Pin #
Symbol
1
FB
2, 8, 10
3
GND
EN_BUCK
4
EN_BAT
5
ISET
6
7
9
11
BAT
STAT
ADP
LX
12
EP
VIN
Function
Feedback input. This pin must be connected directly to an external resistor divider.
Nominal voltage is 0.6V.
Ground.
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.
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.
Battery charging and sensing.
Charge status input. Open drain status input.
Input for USB/adapter charger.
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.
Exposed paddle (bottom): connect to ground directly beneath the package.
Pin Configuration
TDFN33-12
(Top View)
FB
GND
EN_BUCK
EN_BAT
ISET
BAT
2
1
12
2
11
3
10
4
9
5
8
6
7
VIN
LX
GND
ADP
GND
STAT
2556.2006.09.1.2
AAT2556
Battery Charger and Step-Down
Converter for Portable Applications
Absolute Maximum Ratings1
Symbol
VIN
VADP
VLX
VFB
VEN
VX
TJ
TLEAD
Description
Input Voltage to GND
Adapter Voltage to GND
LX to GND
FB to GND
EN_BAT and EN_BUCK to GND
BAT, ISET and STAT 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 VIN + 0.3
-0.3 to VIN + 0.3
-0.3 to 6.0
-0.3 to VADP + 0.3
-40 to 150
300
V
V
V
V
V
V
°C
°C
Value
Units
2.0
50
W
°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.
2556.2006.09.1.2
3
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
Step-Down Converter
VIN
Input Voltage
VUVLO
UVLO Threshold
VOUT
Output Voltage Tolerance2
VOUT
IQ
ISHDN
ILIM
Output Voltage Range
Quiescent Current
Shutdown Current
P-Channel Current Limit
High-Side Switch On Resistance
Low-Side Switch On Resistance
LX Leakage Current
Line Regulation
Feedback Threshold Voltage Accuracy
FB Leakage Current
Oscillator Frequency
RDS(ON)H
RDS(ON)L
ILXLEAK
ΔVLinereg/ΔVIN
VFB
IFB
FOSC
TS
TSD
THYS
VEN(L)
VEN(H)
IEN
Startup Time
Over-Temperature Shutdown Threshold
Over-Temperature Shutdown Hysteresis
Enable Threshold Low
Enable Threshold High
Input Low Current
Min
Typ
2.7
VIN Rising
Hysteresis
VIN Falling
IOUT = 0 to 250mA,
VIN = 2.7V to 5.5V
Max
Units
5.5
2.7
V
V
mV
V
%
200
1.8
-3.0
3.0
0.6
No Load
EN = GND
VIN
1.5
V
µA
µA
mA
Ω
Ω
µA
%/V
V
µA
MHz
100
µs
140
15
°C
°C
V
V
µA
30
1.0
600
0.59
0.42
VIN = 5.5V, VLX = 0 to VIN
VIN = 2.7V to 5.5V
VIN = 3.6V
VOUT = 1.0V
1.0
0.591
From Enable to Output
Regulation
0.2
0.600
0.609
0.2
0.6
VIN = VEN = 5.5V
1.4
-1.0
1.0
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
2556.2006.09.1.2
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
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)
Input High Threshold
VEN(L)
Input Low Threshold
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 = 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 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.
2556.2006.09.1.2
5
AAT2556
Battery Charger and Step-Down
Converter for Portable Applications
Typical Characteristics – Step-Down Converter
Efficiency vs. Load
DC Load Regulation
(VOUT = 1.8V; L = 3.3µH)
100
VIN = 2.7V
VIN = 5.0V
VIN = 3.6V
Output Error (%)
Efficiency (%)
90
(VOUT = 1.8V; L = 3.3µH)
1.0
80
VIN = 5.5V
70
60
VIN = 4.2V
50
40
0.1
1
10
100
0.5
VIN = 3.6V
0.0
VIN = 2.7V
-0.5
1
Output Current (mA)
(VOUT = 1.2V; L = 1.5µH)
Output Error (%)
VIN = 2.7V
90
VIN = 3.6V
70
60
VIN = 5.5V
VIN = 5.0V
50
VIN = 4.2V
40
0.1
1
5.0
10
100
1000
1
10
100
Soft Start
Line Regulation
(VIN = 3.6V; VOUT = 1.8V;
IOUT = 250mA; CFF = 100pF)
(VOUT = 1.8V)
0.5
1.4
0.8
0.0
0.6
VO
0.4
0.2
-2.0
0.0
IL
-0.2
-5.0
-0.4
Inductor Current
(bottom) (A)
1.0
1.0
1000
0.6
1.6
2.0
-4.0
VIN = 3.6V
VIN = 4.2V
-0.5
Output Current (mA)
1.2
-3.0
0.0
Output Current (mA)
3.0
-1.0
VIN = 5.5V
VIN = 2.7V
VEN
4.0
VIN = 5.0V
0.5
-1.0
0.1
Accuracy (%)
Efficiency (%)
1000
1.0
100
Enable and Output Voltage
(top) (V)
100
DC Load Regulation
(VOUT = 1.2V; L = 1.5µH)
30
10
Output Current (mA)
Efficiency vs. Load
80
VIN = 5.0V
VIN = 4.2V
-1.0
0.1
1000
VIN = 5.5V
IOUT = 0mA
0.4
0.3
IOUT = 50mA
0.2
IOUT = 150mA
0.1
0.0
-0.1
IOUT = 10mA
IOUT = 250mA
-0.2
-0.3
2.5
3.0
3.5
4.0
4.5
5.0
5.5
6.0
Time (100µs/div)
Input Voltage (V)
6
2556.2006.09.1.2
AAT2556
Battery Charger and Step-Down
Converter for Portable Applications
Typical Characteristics – Step-Down Converter
Output Voltage Error vs. Temperature
Switching Frequency Variation
vs. Temperature
(VIN = 3.6V; VOUT = 1.8V; IOUT = 250mA)
(VIN = 3.6V; VOUT = 1.8V)
3.0
2.0
8.0
Variation (%)
Output Error (%)
10.0
1.0
0.0
-1.0
6.0
4.0
2.0
0.0
-2.0
-4.0
-6.0
-2.0
-8.0
-3.0
-40
-20
0
20
40
60
80
-10.0
100
-40
-20
0
Temperature (°°C)
20
40
60
80
100
Temperature (°°C)
Frequency Variation vs. Input Voltage
No Load Quiescent Current vs. Input Voltage
(VOUT = 1.8V)
50
1.0
Supply Current (µA)
Frequency Variation (%)
2.0
0.0
-1.0
-2.0
-3.0
-4.0
2.7
3.1
3.5
3.9
4.3
4.7
5.1
85°C
35
30
25°C
25
-40°C
20
15
3.1
3.9
4.3
4.7
5.1
Input Voltage (V)
P-Channel RDS(ON) vs. Input Voltage
N-Channel RDS(ON) vs. Input Voltage
5.5
750
100°C
800
700
700
600
25°C
500
120°C
650
85°C
RDS(ON)L (mΩ
Ω)
120°C
85°C
550
500
450
25°C
350
3.0
3.5
4.0
4.5
Input Voltage (V)
2556.2006.09.1.2
5.0
5.5
6.0
100°C
600
400
400
2.5
3.5
Input Voltage (V)
900
RDS(ON)H (mΩ
Ω)
40
10
2.7
5.5
1000
300
45
300
2.5
3.0
3.5
4.0
4.5
5.0
5.5
6.0
Input Voltage (V)
7
AAT2556
Battery Charger and Step-Down
Converter for Portable Applications
Typical Characteristics – Step-Down Converter
Load Transient Response
Load Transient Response
(10mA to 250mA; VIN = 3.6V; VOUT = 1.8V;
COUT = 4.7µF; CFF = 100pF)
(10mA to 250mA; VIN = 3.6V; VOUT = 1.8V; COUT = 4.7µF)
1.7
IO
1.6
ILX
1.5
1.4
1.3
1.2
1.9
Output Voltage
(top) (V)
Output Voltage
(top) (V)
VO
1.8
2.0
1.8
1.4
1.6
0.8
1.4
0.4
ILX
0.0
1.2
-0.2
Line Response
Output Ripple
(VIN = 3.6V; VOUT = 1.8V; IOUT = 1mA)
40
6.5
6.0
5.5
1.70
5.0
1.65
4.5
VIN
4.0
1.55
3.5
1.50
3.0
Time (25µs/div)
20
0
0.07
0.06
VO
0.05
-20
0.04
-40
0.03
-60
0.02
-80
-100
0.01
IL
Inductor Current
(bottom) (A)
VO
Output Voltage
(AC Coupled) (top) (mV)
7.0
Input Voltage
(bottom) (V)
Output Voltage
(top) (V)
0.2
1.3
Time (25µs/div)
1.75
1.60
0.6
IO
1.5
(VOUT = 1.8V @ 250mA; CFF = 100pF)
1.90
1.80
1.0
1.7
Time (25µs/div)
1.85
1.2
VO
Load and Inductor Current
(bottom) (200mA/div)
1.9
Load and Inductor Current
(bottom) (200mA/div)
2.0
0.00
-120
-0.01
Time (2µs/div)
Output Ripple
(VIN = 3.6V; VOUT = 1.8V; IOUT = 250mA)
20
0
0.8
0.7
VO
0.6
-20
0.5
-40
0.4
-60
0.3
-80
-100
0.2
IL
Inductor Current
(bottom) (A)
Output Voltage
(AC Coupled) (top) (V)
40
0.1
-120
0.0
Time (200ns/div)
8
2556.2006.09.1.2
AAT2556
Battery Charger and Step-Down
Converter for Portable Applications
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
50
75
100
(RSET = 8.06kΩ
Ω)
210
220
208
210
205
VBAT = 3.3V
ICH (mA)
ICH (mA)
25
Constant Charging Current vs. Temperature
(RSET = 8.06kΩ
Ω)
200
190
VBAT = 3.6V
VBAT = 4V
203
200
198
195
180
170
0
Temperature (°C)
VADP (V)
193
4
4.25
4.5
4.75
5
5.25
5.5
VADP (V)
2556.2006.09.1.2
5.75
6
6.25
6.5
190
-50
-25
0
25
50
75
100
Temperature (°C)
9
AAT2556
Battery Charger and Step-Down
Converter for Portable Applications
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)
(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
5
5.2
5.4
5.6
5.8
6
6.2
6.4
Recharging Threshold Voltage
vs. Temperature
Sleep Mode Current vs. Supply Voltage
(RSET = 8.06kΩ
Ω)
800
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
-50
4.8
VADP (V)
4.18
4.02
RSET = 31.6kΩ
RSET = 16.2kΩ
Temperature (°C)
(RSET = 8.06kΩ
Ω)
VRCH (V)
40
10
19.4
-25
0
25
50
Temperature (°C)
10
RSET = 3.24kΩ
50
0
100
60
20.6
-25
75
Preconditioning Charge Current
vs. Supply Voltage
20.8
-50
50
Temperature (°C)
Preconditioning Charge Current
vs. Temperature
19.2
25
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)
2556.2006.09.1.2
AAT2556
Battery Charger and Step-Down
Converter for Portable Applications
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
-40°C
1
-40°C
VEN(L) (V)
VEN(H) (V)
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)
2556.2006.09.1.2
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)
11
AAT2556
Battery Charger and Step-Down
Converter for Portable Applications
Functional Block Diagram
Reverse Blocking
BAT
ADP
+
Constant
Current
STAT
OverTemperature
Protection
Charge
Control
+
-
ISET
VREF
EN_BAT
UVLO
VIN
FB
DH
+
LX
Logic
VREF
DL
EN_BUCK
Input
GND
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 current and constant voltage algorithm. The battery
charger operates from the adapter/USB input voltage range from 4V to 6.5V. The adapter/USB
charging current level can be programmed up to
500mA for rapid charging applications. A status
monitor output pin is provided to indicate the battery charge state by directly driving one external
LED. Internal device temperature and charging
12
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.
The step-down converter operates with an input voltage of 2.7V to 5.5V. The switching frequency is
1.5MHz, minimizing the size of the inductor. Under
light load conditions, the device enters power-saving
mode; the switching frequency is reduced, and the
converter consumes 30µA of current, making it ideal
for battery-operated applications. The output voltage is programmable from VIN to as low as 0.6V.
2556.2006.09.1.2
AAT2556
Battery Charger and Step-Down
Converter for Portable Applications
Power devices are sized for 250mA current capability 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.
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 control will automatically resume charging in the
appropriate mode for the condition of the battery. If
the input voltage of the step-down converter drops
below UVLO, the internal circuit will shut down.
Protection Circuitry
Over-Voltage Protection
An over-voltage protection event is defined as a
condition where the voltage on the BAT pin
exceeds the over-voltage protection threshold
(VOVP). If this over-voltage condition occurs, the
charger control circuitry will shut down the device.
The charger will resume normal charging operation
after the over-voltage condition is removed.
Current Limit, Over-Temperature Protection
For overload conditions, the peak input current is
limited at the step-down converter. As load impedance decreases and the output voltage falls closer
to zero, more power is dissipated internally, which
causes the internal die temperature to rise. In this
case, the thermal protection circuit completely disables switching, which protects the device from
damage.
The battery charger has a thermal protection circuit
which will shut down charging functions when the
internal die temperature exceeds the preset ther-
2556.2006.09.1.2
mal limit threshold. Once the internal die temperature 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-programmed 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 voltage for all load and line conditions. Internal loop
compensation terminates the transconductance
voltage error amplifier output. The error amplifier
reference is fixed at 0.6V.
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.
13
AAT2556
Battery Charger and Step-Down
Converter for Portable Applications
Charge Complete Voltage
Preconditioning
Trickle Charge
Phase
Constant Current
Charge Phase
Constant Voltage
Charge Phase
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.
Pre-conditioning continues until the battery voltage
reaches VMIN. 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. 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.
14
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.
2556.2006.09.1.2
AAT2556
Battery Charger and Step-Down
Converter for Portable Applications
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 ADP > VBAT
No
Voltage Phase Test
IBAT > ITERM
No
Charge Completed
2556.2006.09.1.2
15
AAT2556
Battery Charger and Step-Down
Converter for Portable Applications
Application Information
Soft Start / Enable
Normal
ICHARGE (mA)
Set Resistor
Ω)
Value R2 (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 step-down converter features a soft start that
limits the inrush current and eliminates output voltage 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.
Adapter or USB Power Input
Constant current charge levels up to 500mA may
be programmed by the user when powered from a
sufficient input power source. The battery charger
will operate from the adapter input over a 4.0V to
6.5V range. The constant current fast charge current for the adapter input is set by the RSET resistor
connected between ISET and ground. Refer to
Table 1 for recommended RSET values for a desired
constant current charge level.
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
1000
ICH (mA)
Pulling EN_BUCK to logic low forces the converter
in a low power, non-switching state, and it consumes less than 1µA of quiescent current.
Connecting it to logic high enables the converter
and resumes normal operation.
Table 1: RSET Values.
100
10
1
1
10
100
1000
RSET (kΩ
Ω)
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 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.
Event Description
Status
No battery charging activity
Battery charging via adapter
or USB port
Charging completed
OFF
ON
OFF
Table 2: LED Status Indicator.
2556.2006.09.1.2
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; therefore, a ballast resistor should be placed between
the LED cathode and the STAT pin. LED current
consumption will add to the overall thermal power
budget for the device package, hence it is good to
keep the LED drive current to a minimum. 2mA
should be sufficient to drive most low-cost green or
red LEDs. It is not recommended to exceed 8mA
for driving an individual status LED.
The required ballast resistor values can be estimated using the following formulas:
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.
3000
(VADP - VF(LED))
R 1=
ILED
PD(MAX) (mW)
2500
Example:
2000
1500
1000
500
R1 =
0
(5.5V - 2.0V)
= 1.75kΩ
2mA
0
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 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:
PD(MAX) =
2556.2006.09.1.2
(TJ(MAX) - TA)
θJA
40
60
80
100
120
TA (°°C)
Note: Red LED forward voltage (VF) is typically
2.0V @ 2mA.
Thermal Considerations
20
Figure 3: Maximum Power Dissipation.
Next, the power dissipation of the battery charger
can be calculated by the following equation:
PD = [(VADP - VBAT) · ICH + (VADP · IOP)]
Where:
PD
= Total Power Dissipation by the Device
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]
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.
17
AAT2556
Battery Charger and Step-Down
Converter for Portable Applications
ICH(MAX) =
IQ is the step-down converter quiescent current.
The term tsw is used to estimate the full load stepdown converter switching losses.
(PD(MAX) - VIN · IOP)
VIN - VBAT
(TJ(MAX) - TA) - V · I
IN
OP
θJA
ICH(MAX) =
VIN - VBAT
For the condition where the step-down converter is
in dropout at 100% duty cycle, the total device dissipation reduces to:
In general, the worst condition is the greatest voltage drop across the IC, when battery voltage is
charged up to the preconditioning voltage threshold. Figure 4 shows the maximum charge current in
different ambient temperatures.
500
ICC(MAX) (mA)
400
TA = 60°C
300
TA = 85°C
Since RDS(ON), quiescent current, and switching
losses all vary with input voltage, the total losses
should be investigated over the complete input
voltage range.
Given the total losses, the maximum junction temperature can be derived from the θJA for the
TDFN33-12 package which is 50°C/W.
200
TJ(MAX) = PTOTAL · ΘJA + 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)
Figure 4: Maximum Charging Current Before
Thermal Cycling Becomes Active.
There are three types of losses associated with the
step-down converter: switching losses, conduction
losses, and quiescent current losses. Conduction
losses are associated with the RDS(ON) characteristics of the power output switching devices.
Switching losses are dominated by the gate charge
of the power output switching devices. At full load,
assuming continuous conduction mode (CCM), a
simplified form of the losses is given by:
PTOTAL =
IO2 · (RDSON(H) · VO + RDSON(L) · [VIN - VO])
VIN
+ (tsw · FS · IO + IQ) · VIN
18
PTOTAL = IO2 · RDSON(H) + IQ · VIN
Capacitor Selection
Battery Charger Input Capacitor (C1)
In general, it is good design practice to place a
decoupling capacitor between the ADP pin and
GND. An input capacitor in the range of 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.
Step-Down Converter Input Capacitor (C3)
Select a 4.7µF to 10µF X7R or X5R ceramic capacitor for the input. To estimate the required input
capacitor size, determine the acceptable input ripple level (VPP) and solve for CIN. The calculated
value varies with input voltage and is a maximum
when VIN is double the output voltage.
2556.2006.09.1.2
AAT2556
Battery Charger and Step-Down
Converter for Portable Applications
CIN =
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 ⎛
V ⎞
· 1- O
VIN ⎝
VIN ⎠
⎛ VPP
⎞
- ESR · FS
⎝ IO
⎠
The proper placement of the input capacitor (C3)
can be seen in the evaluation board layout in
Figure 6.
VO ⎛
V ⎞
1
· 1 - O = for VIN = 2 · VO
VIN ⎝
VIN ⎠
4
CIN(MIN) =
1
⎛ VPP
⎞
- ESR · 4 · FS
⎝ IO
⎠
Always examine the ceramic capacitor DC voltage
coefficient characteristics when selecting the proper value. For example, the capacitance of a 10µF,
6.3V, X5R ceramic capacitor with 5.0V DC applied
is actually about 6µF.
The maximum input capacitor RMS current is:
IRMS = IO ·
VO ⎛
V ⎞
· 1- O
VIN ⎝
VIN ⎠
The input capacitor RMS ripple current varies with
the input and output voltage and will always be less
than or equal to half of the total DC load current.
VO ⎛
V ⎞
· 1- O =
VIN ⎝
VIN ⎠
D · (1 - D) =
0.52 =
1
2
for VIN = 2 · VO
IRMS(MAX) =
VO
IO
2
⎛
V ⎞
· 1- O
The term VIN ⎝ VIN ⎠ appears in both the input
voltage ripple and input capacitor RMS current
equations and is a maximum when VO is twice VIN.
This is why the input voltage ripple and the input
capacitor RMS current ripple are a maximum at
50% duty cycle.
The input capacitor provides a low impedance loop
for the edges of pulsed current drawn by the stepdown converter. Low ESR/ESL X7R and X5R
2556.2006.09.1.2
A laboratory test set-up typically consists of two
long wires running from the bench power supply to
the evaluation board input voltage pins. The inductance of these wires, along with the low-ESR
ceramic input capacitor, can create a high Q network that may affect converter performance. This
problem often becomes apparent in the form of
excessive ringing in the output voltage during load
transients. Errors in the loop phase and gain measurements can also result.
Since the inductance of a short PCB trace feeding
the input voltage is significantly lower than the
power leads from the bench power supply, most
applications do not exhibit this problem.
In applications where the input power source lead
inductance cannot be reduced to a level that does
not affect the converter performance, a high ESR
tantalum or aluminum electrolytic capacitor should
be placed in parallel with the low ESR, ESL bypass
ceramic capacitor. This dampens the high Q network and stabilizes the system.
Battery Charger Output Capacitor (C2)
The AAT2556 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 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.
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 typically provides sufficient bulk capacitance to stabilize the output during large load transitions and has
the ESR and ESL characteristics necessary for low
output ripple. For enhanced transient response and
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.
The output voltage droop due to a load transient is
dominated by the capacitance of the ceramic output capacitor. During a step increase in load current, the ceramic output capacitor alone supplies
the load current until the loop responds. Within two
or three switching cycles, the loop responds and
the inductor current increases to match the load
current demand. The relationship of the output voltage droop during the three switching cycles to the
output capacitance can be estimated by:
COUT =
3 · ΔILOAD
VDROOP · FS
Once the average inductor current increases to the
DC load level, the output voltage recovers. The
above equation establishes a limit on the minimum
value for the output capacitor with respect to load
transients.
The internal voltage loop compensation also limits
the minimum output capacitor value to 4.7µF. 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:
IRMS(MAX) =
1
2· 3
·
VOUT · (VIN(MAX) - VOUT)
L · FS · VIN(MAX)
Dissipation due to the RMS current in the ceramic output capacitor ESR is typically minimal,
resulting in less than a few degrees rise in hotspot temperature.
Inductor Selection
The step-down converter uses peak current mode
control with slope compensation to maintain stability for duty cycles greater than 50%. The output
inductor value must be selected so the inductor
20
current down slope meets the internal slope compensation requirements. The internal slope compensation 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.
m=
L=
0.75 ⋅ VO 0.75 ⋅ 1.8V
A
=
= 0.45
µsec
L
3.0µH
0.75 ⋅ VO
=
m
0.75 ⋅ VO
µsec
≈ 1.67 A ⋅ VO
A
0.45A µsec
For most designs, the step-down converter operates
with an inductor value of 1µH to 4.7µH. Table 3 displays inductor values for the AAT2556 with different
output voltage options.
Manufacturer's specifications list both the inductor
DC current rating, which is a thermal limitation, and
the peak current rating, which is determined by the
saturation characteristics. The inductor should not
show any appreciable saturation under normal load
conditions. Some inductors may meet the peak and
average current ratings yet result in excessive losses due to a high DCR. Always consider the losses
associated with the DCR and its effect on the total
converter efficiency when selecting an inductor.
The 3.0µH 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.
Output Voltage (V)
L1 (µH)
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
5.6
Table 3: Inductor Values.
2556.2006.09.1.2
AAT2556
Battery Charger and Step-Down
Converter for Portable Applications
Adjustable Output Resistor Selection
Resistors R3 and R4 of Figure 5 program the output to regulate at a voltage higher than 0.6V. To
limit the bias current required for the external feedback resistor string while maintaining good noise
immunity, the suggested value for R4 is 59kΩ.
Decreased resistor values are necessary to maintain noise immunity on the FB pin, resulting in
increased quiescent current. Table 4 summarizes
the resistor values for various output voltages.
Ω
R4 = 59kΩ
Ω
R4 = 221kΩ
VOUT (V)
Ω)
R3 (kΩ
Ω)
R3 (kΩ
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
124
137
187
267
75
113
150
187
221
261
301
332
442
464
523
715
1000
⎛ VOUT ⎞
⎛ 3.3V ⎞
R3 = V
-1 · R4 = 0.6V - 1 · 59kΩ = 267kΩ
⎝ 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
BAT
R4
59k
C2
2.2µF
VIN
R3
118k
1
2
3
4
5
6
L1
R1
1K
1 2 3
VOUT
C4
4.7µF
12
11
10
9
8
7
R2
8.06K
JP3
VOUT
3µH
U1 AAT2556
FB
VIN
GND
LX
EN_BUCK GND
EN_BAT ADP
ISET
GND
BAT
STAT
ADP
C3
4.7uF
C5
100pF
Buck Input
D1
JP1
0Ω
C1
10µF
RED LED
1 2
Enable_Buck
JP2
Enable_Bat
Figure 5: AAT2556 Evaluation Board Schematic.
2556.2006.09.1.2
21
AAT2556
Battery Charger and Step-Down
Converter for Portable Applications
Printed Circuit Board Layout
Considerations
For the best results, it is recommended to physically 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.
Figure 6: AAT2556 Evaluation Board
Top Side Layout.
22
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 highcurrent load trace will degrade DC load regulation. Feedback resistors should be placed as
closely as possible to the FB pin (Pin 1) to minimize the length of the high impedance feedback
trace. If possible, they should also be placed
away from the LX (switching node) and inductor
to improve noise immunity.
4. The resistance of the trace from 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.
5. A high density, small footprint layout can be
achieved using an inexpensive, miniature, nonshielded, high DCR inductor.
Figure 7: AAT2556 Evaluation Board
Bottom Side Layout.
2556.2006.09.1.2
AAT2556
Battery Charger and Step-Down
Converter for Portable Applications
Component
U1
C1
C2
C3, C4
C5
L1
R1
R2
R3
R4
JP1
JP2, JP3, JP4
D1
Part Number
Description
Manufacturer
AAT2556IWP-T1
Battery Charger and Step-Down Converter
for Portable Applications; TDFN33-12 Package
CER 10µF 10V 20% X5R 0603
CER 2.2µF 6.3V 10% X7R 0603
CER 4.7µF 6.3V 10% X7R 0603
CER 100pF 50V 5% R2H 0603
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
Connecting Header, 2mm Zip
Red LED; 1206
AnalogicTech
ECJ-1VB0J106M
GRM185B30J225KE25D
GRM188R60J475KE19B
GRM1886R1H101JZ01J
CDRH2D09-3R0
Chip Resistor
Chip Resistor
Chip Resistor
Chip Resistor
Chip Resistor
PRPN401PAEN
CMD15-21SRC/TR8
Panasonic - ECG
Murata
Murata
Murata
Sumida
Vishay
Vishay
Vishay
Vishay
Vishay
Sullins Electronics
Chicago Miniature Lamp
Table 5: AAT2556 Evaluation Board Component Listing.
2556.2006.09.1.2
23
AAT2556
Battery Charger and Step-Down
Converter for Portable Applications
Step-Down Converter Design Example
Specifications
VO
= 1.8V @ 250mA, Pulsed Load ΔILOAD = 200mA
VIN
= 2.7V to 4.2V (3.6V nominal)
FS
= 1.5MHz
TAMB
= 85°C
1.8V Output Inductor
L1 = 1.67
µsec
µsec
⋅ VO2 = 1.67
⋅ 1.8V = 3µH
A
A
(use 3.0µH; see Table 3)
For Sumida inductor CDRH2D09-3R0, 3.0µH, DCR = 150mΩ.
ΔIL1 =
⎛
VO
V ⎞
1.8V
1.8V ⎞
⎛
⋅ 1- O =
⋅ 1= 228mA
L1 ⋅ FS ⎝
VIN⎠ 3.0µH ⋅ 1.5MHz ⎝
4.2V ⎠
IPKL1 = IO +
ΔIL1
= 250mA + 114mA = 364mA
2
PL1 = IO2 ⋅ DCR = 250mA2 ⋅ 150mΩ = 9.375mW
1.8V Output Capacitor
VDROOP = 0.1V
COUT =
3 · ΔILOAD
3 · 0.2A
=
= 4µF; use 4.7µF
0.1V · 1.5MHz
VDROOP · FS
IRMS =
(VO) · (VIN(MAX) - VO)
1
1.8V · (4.2V - 1.8V)
·
= 66mArms
=
3.0µH
· 1.5MHz · 4.2V
·
V
L1
·
F
2· 3
2· 3
S
IN(MAX)
1
·
Pesr = esr · IRMS2 = 5mΩ · (66mA)2 = 21.8µW
24
2556.2006.09.1.2
AAT2556
Battery Charger and Step-Down
Converter for Portable Applications
Input Capacitor
Input Ripple VPP = 25mV
CIN =
IRMS =
1
⎛ VPP
⎞
- ESR · 4 · FS
⎝ IO
⎠
=
1
= 1.38µF (use 4.7µF)
⎛ 25mV
⎞
- 5mΩ · 4 · 1.5MHz
⎝ 0.2A
⎠
IO
= 0.1Arms
2
P = esr · IRMS2 = 5mΩ · (0.1A)2 = 0.05mW
AAT2556 Losses
PTOTAL =
IO2 · (RDSON(H) · VO + RDSON(L) · [VIN -VO])
VIN
+ (tsw · FS · IO + IQ) · VIN
=
0.22 · (0.59Ω · 1.8V + 0.42Ω · [4.2V - 1.8V])
4.2V
+ (5ns · 1.5MHz · 0.2A + 30µA) · 4.2V = 26.14mW
TJ(MAX) = TAMB + ΘJA · PLOSS = 85°C + (50°C/W) · 26.14mW = 86.3°C
2556.2006.09.1.2
25
AAT2556
Battery Charger and Step-Down
Converter for Portable Applications
Output Voltage
VOUT (V)
Ω
R4 = 59kΩ
Ω)
R3 (kΩ
Ω1
R4 = 221kΩ
Ω)
R3 (kΩ
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
—
19.6
29.4
39.2
49.9
59.0
68.1
78.7
88.7
118
124
137
187
267
—
75
113
150
187
221
261
301
332
442
464
523
715
1000
1.5
1.5
1.5
1.5
1.5
1.5
1.5
2.2
2.7
3.0/3.3
3.0/3.3
3.0/3.3
3.9/4.2
5.6
Table 6: Step-Down Converter Component Values.
Manufacturer
Sumida
Sumida
Sumida
Sumida
Sumida
Sumida
Sumida
Sumida
Sumida
Sumida
Sumida
Taiyo Yuden
Taiyo Yuden
Taiyo Yuden
Taiyo Yuden
FDK
FDK
FDK
FDK
Part Number
Inductance
(µH)
Max DC
Current (mA)
DCR
Ω)
(mΩ
Size (mm)
LxWxH
Type
CDRH2D09-1R5
CDRH2D09-2R2
CDRH2D09-2R5
CDRH2D09-3R0
CDRH2D09-3R9
CDRH2D09-4R7
CDRH2D09-5R6
CDRH2D11-1R5
CDRH2D11-2R2
CDRH2D11-3R3
CDRH2D11-4R7
NR3010
NR3010
NR3010
NR3010
MIPWT3226D-1R5
MIPWT3226D-2R2
MIPWT3226D-3R0
MIPWT3226D-4R2
1.5
2.2
2.5
3
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
4.2
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
78
98
135
80
95
140
190
90
100
120
140
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
Shielded
Shielded
Shielded
Shielded
Shielded
Shielded
Shielded
Shielded
Shielded
Shielded
Shielded
Chip shielded
Chip shielded
Chip shielded
Chip shielded
Table 7: Suggested Inductors and Suppliers.
1. For reduced quiescent current, R4 = 221kΩ.
2. R4 is opened, R3 is shorted.
26
2556.2006.09.1.2
AAT2556
Battery Charger and Step-Down
Converter for Portable Applications
Manufacturer
Murata
Murata
Part Number
Value
(µF)
Voltage
Rating
Temp.
Co.
Case
Size
GRM118R60J475KE19B
GRM188R60J106ME47D
4.7
10
6.3
6.3
X5R
X5R
0603
0603
Table 8: Surface Mount Capacitors.
2556.2006.09.1.2
27
AAT2556
Battery Charger and Step-Down
Converter for Portable Applications
Ordering Information
Package
Marking1
Part Number (Tape and Reel)2
TDFN33-12
SPXYY
AAT2556IWP-CA-T1
All AnalogicTech products are offered in Pb-free packaging. The term “Pb-free” means
semiconductor products that are in compliance with current RoHS standards, including
the requirement that lead not exceed 0.1% by weight in homogeneous materials. For more
information, please visit our website at http://www.analogictech.com/pbfree.
Legend
Voltage
Adjustable
(0.6V)
0.9
1.2
1.5
1.8
1.9
2.5
2.6
2.7
2.8
2.85
2.9
3.0
3.3
4.2
Code
A
B
E
G
I
Y
N
O
P
Q
R
S
T
W
C
1. XYY = assembly and date code.
2. Sample stock is generally held on part numbers listed in BOLD.
28
2556.2006.09.1.2
AAT2556
Battery Charger and Step-Down
Converter for Portable Applications
Package Information
TDFN33-12
2.40 ± 0.05
Detail "B"
3.00 ± 0.05
Index Area
(D/2 x E/2)
0.3 ± 0.10 0.16 0.375 ± 0.125
0.075 ± 0.075
3.00 ± 0.05
1.70 ± 0.05
Top View
Bottom View
Pin 1 Indicator
(optional)
0.23 ± 0.05
Detail "A"
0.45 ± 0.05
0.1 REF
0.05 ± 0.05
0.229 ± 0.051
+ 0.05
0.8 -0.20
7.5° ± 7.5°
Option A:
C0.30 (4x) max
Chamfered corner
Side View
Option B:
R0.30 (4x) max
Round corner
Detail "B"
Detail "A"
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 subject 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 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.
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830 E. Arques Avenue, Sunnyvale, CA 94085
Phone (408) 737-4600
Fax (408) 737-4611
2556.2006.09.1.2
29