AAT2556_202177B.pdf

DATA SHEET
AAT2556
Battery Charger and Step-Down Converter for Portable Applications
General Description
Features
The AAT2556 is a member of Skyworks' Total Power
Management IC (TPMIC™) product family. It is a fully
integrated 500mA battery charger plus a 250mA stepdown 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 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
• -40°C to +85°C Temperature Range
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.
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
BATT -
ISET
FB
RFB2
RSET
GND
Battery Pack
RFB1
COUT
System
Enable
Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • sales@skyworksinc.com • www.skyworksinc.com
202177B • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • March 19, 2013
1
DATA SHEET
AAT2556
Battery Charger and Step-Down Converter for Portable Applications
Pin Descriptions
Pin #
Symbol
1
2, 8, 10
FB
GND
3
EN_BUCK
4
EN_BAT
5
ISET
6
7
9
BAT
STAT
ADP
11
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
Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • sales@skyworksinc.com • www.skyworksinc.com
202177B • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • March 19, 2013
DATA SHEET
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
JA
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.
Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • sales@skyworksinc.com • www.skyworksinc.com
202177B • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • March 19, 2013
3
DATA SHEET
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
VOUT
VOUT
IQ
ISHDN
ILIM
RDS(ON)H
RDS(ON)L
ILXLEAK
VLinereg/
VIN
VFB
IFB
FOSC
TS
TSD
THYS
VEN(L)
VEN(H)
IEN
UVLO Threshold
Output Voltage Tolerance2
Output Voltage Range
Quiescent Current
Shutdown Current
P-Channel Current Limit
High-Side Switch On Resistance
Low-Side Switch On Resistance
LX Leakage Current
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
%
V
μA
μA
mA


μA
200
1.8
-3.0
0.6
No Load
EN = GND
3.0
VIN
30
1.0
600
0.59
0.42
VIN = 5.5V, VLX = 0 to VIN
Line Regulation
VIN = 2.7V to 5.5V
Feedback Threshold Voltage Accuracy
FB Leakage Current
Oscillator Frequency
Startup Time
Over-Temperature Shutdown Threshold
Over-Temperature Shutdown Hysteresis
Enable Threshold Low
Enable Threshold High
Input Low Current
VIN = 3.6V
VOUT = 1.0V
1.0
0.2
0.591
0.600
%/V
0.609
0.2
1.5
100
140
15
From Enable to Output Regulation
0.6
VIN = VEN = 5.5V
1.4
-1.0
1.0
V
μA
MHz
μs
°C
°C
V
V
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
Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • sales@skyworksinc.com • www.skyworksinc.com
202177B • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • March 19, 2013
DATA SHEET
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
VUVLO
Under-Voltage Lockout (UVLO)
UVLO Hysteresis
IOP
Operating Current
Shutdown Current
ISHUTDOWN
ILEAKAGE
Reverse Leakage Current from BAT Pin
Voltage Regulation
VBAT_EOC
End of Charge Accuracy
VCH/VCH
Output Charge Voltage Tolerance
VMIN
Preconditioning Voltage Threshold
VRCH
Battery Recharge Voltage Threshold
Current Regulation
ICH
Charge Current Programmable Range
ICH/ICH
Charge Current Regulation Tolerance
ISET Pin Voltage
VSET
KI_A
Current Set Factor: ICH/ISET
Charging Devices
RDS(ON)
Charging Transistor On Resistance
Logic Control/Protection
Input High Threshold
VEN(H)
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
Rising Edge
Min
Typ
4.0
3
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

10
2
800
VADP = 5.5V
0.9
1.6
0.4
0.4
8
STAT Pin Sinks 4mA
ICH = 100mA
V
%
V
V
4.4
10
10
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.
Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • sales@skyworksinc.com • www.skyworksinc.com
202177B • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • March 19, 2013
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DATA SHEET
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
10
Output Current (mA)
(VOUT = 1.2V; L = 1.5µH)
1.0
100
Efficiency (%)
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
VIN = 5.0V
0.5
VIN = 5.5V
0.0
VIN = 3.6V
VIN = 4.2V
-0.5
VIN = 2.7V
10
100
-1.0
0.1
1000
1
Soft Start
Line Regulation
(VOUT = 1.8V)
1.2
2.0
1.0
1.0
0.8
0.6
0.0
VO
0.4
0.2
-2.0
-3.0
-4.0
0.5
1.4
3.0
-1.0
0.0
IL
-0.2
-5.0
-0.4
Time (100µs/div)
1000
0.6
1.6
VEN
4.0
100
(VIN = 3.6V; VOUT = 1.8V;
IOUT = 250mA; CFF = 100pF)
Accuracy (%)
5.0
10
Output Current (mA)
Inductor Current
(bottom) (A)
Enable and Output Voltage
(top) (V)
Output Current (mA)
6
1000
DC Load Regulation
(VOUT = 1.2V; L = 1.5µH)
30
100
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
Input Voltage (V)
Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • sales@skyworksinc.com • www.skyworksinc.com
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5.5
6.0
DATA SHEET
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
30
25°C
25
-40°C
20
15
3.1
3.9
4.3
4.7
5.1
P-Channel RDS(ON) vs. Input Voltage
N-Channel RDS(ON) vs. Input Voltage
5.5
750
120°C
100°C
800
700
120°C
650
85°C
700
600
25°C
85°C
550
500
450
25°C
350
3.0
3.5
4.0
4.5
Input Voltage (V)
5.0
5.5
6.0
100°C
600
400
400
2.5
3.5
Input Voltage (V)
RDS(ON)L (mΩ
Ω)
RDS(ON)H (mΩ
Ω)
35
Input Voltage (V)
900
300
40
10
2.7
5.5
1000
500
45
300
2.5
3.0
3.5
4.0
4.5
5.0
5.5
6.0
Input Voltage (V)
Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • sales@skyworksinc.com • www.skyworksinc.com
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DATA SHEET
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
0.2
1.3
0.0
1.2
-0.2
Line Response
Output Ripple
(VOUT = 1.8V @ 250mA; CFF = 100pF)
(VIN = 3.6V; VOUT = 1.8V; IOUT = 1mA)
6.5
6.0
1.75
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
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
Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • sales@skyworksinc.com • www.skyworksinc.com
202177B • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • March 19, 2013
Inductor Current
(bottom) (A)
VO
40
Output Voltage
(AC Coupled) (top) (mV)
7.0
1.85
Input Voltage
(bottom) (V)
Output Voltage
(top) (V)
0.6
IO
1.5
Time (25µs/div)
1.90
1.60
1.0
1.7
Time (25µs/div)
1.80
1.2
VO
Load and Inductor Current
(bottom) (200mA/div)
1.9
Load and Inductor Current
(bottom) (200mA/div)
2.0
DATA SHEET
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
RSET (kΩ
Ω)
VBAT (V)
End of Charge Battery Voltage
vs. Supply Voltage
End of Charge Voltage Regulation
vs. Temperature
4.3
(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)
5.75
6
6.25
6.5
190
-50
-25
0
25
50
75
100
Temperature (°C)
Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • sales@skyworksinc.com • www.skyworksinc.com
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DATA SHEET
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)
Preconditioning Charge Current
vs. Temperature
(RSET = 8.06kΩ
Ω)
ITRICKLE (mA)
ITRICKLE (mA)
20.4
20.2
20.0
19.8
19.6
25
50
75
RSET = 8.06kΩ
20
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
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)
4.16
4.02
RSET = 31.6kΩ
RSET = 16.2kΩ
Temperature (°C)
4.18
VRCH (V)
RSET = 5.36kΩ
30
0
100
(RSET = 8.06kΩ
Ω)
-25
0
25
50
Temperature (°C)
10
40
10
19.4
0
100
RSET = 3.24kΩ
50
-25
75
60
20.6
-50
50
Preconditioning Charge Current
vs. Supply Voltage
20.8
19.2
25
Temperature (°C)
75
100
25°C
-40°C
0
4
4.25
4.5
4.75
5
5.25
5.5
5.75
VADP (V)
Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • sales@skyworksinc.com • www.skyworksinc.com
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6.25
6.5
DATA SHEET
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)
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)
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11
DATA SHEET
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 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. Power devices are sized for
12
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.
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DATA SHEET
AAT2556
Battery Charger and Step-Down Converter for Portable Applications
Current Limit, Over-Temperature Protection
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.
For overload conditions, the peak input current is limited
at the step-down converter. As load impedance decreases and the output voltage falls closer to zero, more
power is dissipated internally, which causes the internal
die temperature to rise. In this case, the thermal protection circuit completely disables switching, which protects
the device from damage.
The battery charger has a thermal protection circuit which
will shut down charging functions when the internal die
temperature exceeds the preset thermal limit threshold.
Once the internal die temperature falls below the thermal
limit, normal charging operation will resume.
Pre-conditioning continues until the battery voltage
reaches VMIN. At this point, the charger begins constantcurrent 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.
Control Loop
The AAT2556 contains a compact, current mode stepdown 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 voltageprogrammed 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.
After the charge cycle is complete, the pass device turns
off and the device automatically goes into a power-saving sleep mode. During this time, the series pass device
will block current in both directions, preventing the battery from discharging through the IC.
The battery charger will remain in sleep mode, even if
the charger source is disconnected, until one of the following events occurs: the battery terminal voltage drops
below the VRCH threshold; the charger EN pin is recycled;
or the charging source is reconnected. In all cases, the
charger will monitor all parameters and resume charging
in the most appropriate mode.
Battery Charging Operation
Battery charging commences only after checking several
conditions in order to maintain a safe charging environment. The input supply (ADP) must be above the minimum operating voltage (UVLO) and the enable pin must
be high (internally pulled down). When the battery is
Preconditioning
Trickle Charge
Phase
Constant Current
Charge Phase
Constant Voltage
Charge Phase
Charge Complete Voltage
I = Max CC
Regulated Current
Constant Current Mode
Voltage Threshold
Trickle Charge and
Termination Threshold
I = CC / 10
Figure 1: Current vs. Voltage Profile During Charging Phases.
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DATA SHEET
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
14
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DATA SHEET
AAT2556
Battery Charger and Step-Down Converter for Portable Applications
Application Information
Normal
ICHARGE (mA)
Set Resistor
Value R2 (k)
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
Soft Start / Enable
The EN_BAT pin is internally pulled down. When pulled
to a logic high level, the battery charger is enabled.
When left open or pulled to a logic low level, the battery
charger is shut down and forced into the sleep state.
Charging will be halted regardless of the battery voltage
or charging state. When it is re-enabled, the charge 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.
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.
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.
Table 1: RSET Values.
1000
ICH (mA)
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.
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 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.
Event Description
No battery charging activity
Battery charging via adapter or USB port
Charging completed
Status
OFF
ON
OFF
Table 2: LED Status Indicator.
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DATA SHEET
AAT2556
Battery Charger and Step-Down Converter for Portable Applications
Figure 3 shows the relationship of maximum power dissipation and ambient temperature of the AAT2556.
3000
2500
PD(MAX) (mW)
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 lowcost green or red LEDs. It is not recommended to exceed
8mA for driving an individual status LED.
2000
1500
1000
The required ballast resistor values can be estimated
using the following formulas:
500
0
0
VADP - VF(LED)
R1 =
ILED
40
60
80
100
120
TA (°°C)
Figure 3: Maximum Power Dissipation.
Example:
R1 =
5.5V - 2.0V
= 1.75kΩ
2mA
Next, the power dissipation of the battery charger can
be calculated by the following equation:
Note: Red LED forward voltage (VF) is typically 2.0V @
2mA.
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
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:
(TJ(MAX) - TA)
PD(MAX) =
θJA
Where:
PD(MAX) = Maximum Power Dissipation (W)
JA = Package Thermal Resistance (°C/W)
TJ(MAX) = Maximum Device Junction Temperature (°C)
[135°C]
TA = Ambient Temperature (°C)
16
20
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.
ICH(MAX) =
(PD(MAX) - VIN · IOP)
VIN - VBAT
(TJ(MAX) - TA) - V · I
IN
OP
θJA
ICH(MAX) =
VIN - VBAT
In general, the worst condition is the greatest voltage
drop across the IC, when battery voltage is charged up
to the preconditioning voltage threshold. Figure 4 shows
the maximum charge current in different ambient temperatures.
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DATA SHEET
AAT2556
Battery Charger and Step-Down Converter for Portable Applications
Capacitor Selection
500
ICC(MAX) (mA)
400
TA = 60°C
300
TA = 85°C
200
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 stepdown 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
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.
CIN =
V ⎞
VO ⎛
· 1- O
VIN ⎝
VIN ⎠
⎛ VPP
⎞
- ESR · FS
⎝ IO
⎠
+ (tsw · FS · IO + IQ) · VIN
IQ is the step-down converter quiescent current. The
term tsw is used to estimate the full load step-down converter switching losses.
For the condition where the step-down converter is in
dropout at 100% duty cycle, the total device dissipation
reduces to:
PTOTAL = IO2 · RDSON(H) + IQ · VIN
Since RDS(ON), quiescent current, and switching losses all
vary with input voltage, the total losses should be investigated over the complete input voltage range.
Given the total losses, the maximum junction temperature can be derived from the JA for the TDFN33-12
package which is 50°C/W.
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:
VO ⎛
V ⎞
· 1- O =
VIN ⎝
VIN ⎠
D · (1 - D) =
0.52 =
1
2
TJ(MAX) = PTOTAL · ΘJA + TAMB
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DATA SHEET
AAT2556
Battery Charger and Step-Down Converter for Portable Applications
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.
IRMS = IO ·
VO ⎛
V ⎞
· 1- O
VIN ⎝
VIN ⎠
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 step-down converter. Low ESR/ESL X7R and X5R ceramic capacitors are
ideal for this function. To minimize stray inductance, the
capacitor should be placed as closely as possible to the IC.
This keeps the high frequency content of the input current
localized, minimizing EMI and input voltage ripple.
The proper placement of the input capacitor (C3) can be
seen in the evaluation board layout in Figure 6.
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
18
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 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
VOUT · (VIN(MAX) - VOUT)
L · FS · VIN(MAX)
2· 3
·
Dissipation due to the RMS current in the ceramic output
capacitor ESR is typically minimal, resulting in less than
a few degrees rise in hot-spot temperature.
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DATA SHEET
AAT2556
Battery Charger and Step-Down Converter for Portable Applications
Inductor Selection
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
The step-down converter uses peak current mode control with slope compensation to maintain stability for
duty cycles greater than 50%. The output inductor value
must be selected so the inductor current down slope
meets the internal slope compensation requirements.
The internal slope compensation for the 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
L
3.0µH
µsec
0.75 ⋅ VO
=
m
= 1.67
µsec
0.75 ⋅ VO
≈ 1.67 A ⋅ VO
A
0.45A µsec
µsec
⋅ 3.0V = 5.0µH
A
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 150m DCR and a 470mA DC current rating. At full load, the inductor DC loss is 9.375mW which
gives a 2.08% loss in efficiency for a 250mA, 1.8V output.
Table 3: Inductor Values.
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 59k. 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.
⎛ 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.
R4 = 59k
R4 = 221k
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
124
137
187
267
75
113
150
187
221
261
301
332
442
464
523
715
1000
Table 4: Adjustable Resistor Values For
Step-Down Converter.
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DATA SHEET
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.
2.
20
The input capacitors (C1, C3) should connect as
closely as possible to ADP (Pin 9) and VIN (Pin 12).
C4 and L1 should be connected as closely as possible. The connection of L1 to the LX pin should be as
short as possible. Do not make the node small by
using narrow trace. The trace should be kept wide,
direct, and short.
3.
4.
5.
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 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.
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.
A high density, small footprint layout can be achieved
using an inexpensive, miniature, non-shielded, high
DCR inductor.
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DATA SHEET
AAT2556
Battery Charger and Step-Down Converter for Portable Applications
JP4
1 2 3
BAT
R4
59kΩ
C2
2.2μF
VIN
R3
118kΩ
1
2
3
4
5
6
L1
VOUT
C4
4.7μF
12
11
10
9
8
7
R2
8.06kΩ
R1
1kΩ
D1
JP1
0Ω
C1
10μF
RED LED
1 2
1 2 3
JP3
VOUT
3μH
U1 AAT2556
FB
VIN
GND
LX
EN_BUCK GND
EN_BAT ADP
ISET
GND
BAT
STAT
ADP
C3
4.7μF
C5
100pF
Buck Input
Enable_Buck
JP2
Enable_Bat
Figure 5: AAT2556 Evaluation Board Schematic.
Figure 6: AAT2556 Evaluation Board
Top Side Layout.
Figure 7: AAT2556 Evaluation Board
Bottom Side Layout.
Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • sales@skyworksinc.com • www.skyworksinc.com
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21
DATA SHEET
AAT2556
Battery Charger and Step-Down Converter for Portable Applications
Component
Part Number
U1
AAT2556IWP-T1
C1
C2
C3, C4
C5
L1
R1
R2
R3
R4
JP1
JP2, JP3, JP4
D1
ECJ-1VB0J106M
GRM185B30J225KE25D
GRM188R60J475KE19B
GRM1886R1H101JZ01J
CDRH2D09-3R0
Chip Resistor
Chip Resistor
Chip Resistor
Chip Resistor
Chip Resistor
PRPN401PAEN
CMD15-21SRC/TR8
Description
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, 150m, 3x3x1mm
1K, 5%, 1/4W; 0603
8.06K, 1%, 1/4W; 0603
118K, 1%, 1/4W; 0603
59K, 1%, 1/4W; 0603
0, 5%, 1/4W; 0603
Connecting Header, 2mm Zip
Red LED; 1206
Manufacturer
Skyworks
Panasonic - ECG
Murata
Murata
Murata
Sumida
Vishay
Vishay
Vishay
Vishay
Vishay
Sullins Electronics
Chicago Miniature Lamp
Table 5: AAT2556 Evaluation Board Component Listing.
22
Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • sales@skyworksinc.com • www.skyworksinc.com
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DATA SHEET
AAT2556
Battery Charger and Step-Down Converter for Portable Applications
Step-Down Converter Design Example
Specifications
VO = 1.8V @ 250mA, Pulsed Load ILOAD = 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 (use 3.0μH; see Table 3)
A
A
For Sumida inductor CDRH2D09-3R0, 3.0μH, DCR = 150m.
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
VDROOP · FS
0.1V · 1.5MHz
IRMS =
(VO) · (VIN(MAX) - VO)
1
1.8V · (4.2V - 1.8V)
·
= 66mArms
=
L1 · FS · VIN(MAX)
2 · 3 3.0µH · 1.5MHz · 4.2V
2· 3
1
·
Pesr = esr · IRMS2 = 5mΩ · (66mA)2 = 21.8µW
Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • sales@skyworksinc.com • www.skyworksinc.com
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DATA SHEET
AAT2556
Battery Charger and Step-Down Converter for Portable Applications
Input Capacitor
Input Ripple VPP = 25mV
CIN =
IRMS =
⎛ VPP
⎝ IO
1
1
=
= 1.38µF (use 4.7µF)
⎞
⎛ 25mV
⎞
- 5mΩ · 4 · 1.5MHz
- ESR · 4 · FS
⎠
⎝ 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
24
Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • sales@skyworksinc.com • www.skyworksinc.com
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DATA SHEET
AAT2556
Battery Charger and Step-Down Converter for Portable Applications
Output Voltage
VOUT (V)
R4 = 59k
R3 (k)
R4 = 221k1
R3 (k)
L1 (μH)
0.6
0.8
0.9
1.0
1.1
1.2
1.3
1.4
1.5
1.8
1.85
2.0
2.5
3.3
—
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
2
Table 6: Step-Down Converter Component Values.
Manufacturer
Part Number
Inductance
(μH)
Max DC
Current (mA)
DCR
(m)
Size (mm)
LxWxH
Type
Sumida
Sumida
Sumida
Sumida
Sumida
Sumida
Sumida
Sumida
Sumida
Sumida
Sumida
Taiyo Yuden
Taiyo Yuden
Taiyo Yuden
Taiyo Yuden
FDK
FDK
FDK
FDK
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.
Manufacturer
Part Number
Value (μF)
Voltage Rating
Temp. Co.
Case Size
Murata
Murata
GRM118R60J475KE19B
GRM188R60J106ME47D
4.7
10
6.3
6.3
X5R
X5R
0603
0603
Table 8: Surface Mount Capacitors.
1. For reduced quiescent current, R4 = 221kW.
2. R4 is opened, R3 is shorted.
Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • sales@skyworksinc.com • www.skyworksinc.com
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DATA SHEET
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
Skyworks Green™ products are compliant with
all applicable legislation and are halogen-free.
For additional information, refer to Skyworks
Definition of Green™, document number
SQ04-0074.
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.
26
Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • sales@skyworksinc.com • www.skyworksinc.com
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DATA SHEET
AAT2556
Battery Charger and Step-Down Converter for Portable Applications
Package Information
TDFN33-121
Index Area
0.40 ± 0.05
0.1 REF
C0.3
0.45 ± 0.05
2.40 ± 0.05
3.00 ± 0.05
Detail "A"
3.00 ± 0.05
1.70 ± 0.05
Top View
Bottom View
0.23 ± 0.05
Pin 1 Indicator
(optional)
0.05 ± 0.05
0.23 ± 0.05
0.75 ± 0.05
Detail "A"
Side View
All dimensions in millimeters
1. The leadless package family, which includes QFN, TQFN, DFN, TDFN and STDFN, has exposed copper (unplated) at the end of the lead terminals due to the manufacturing
process. A solder fillet at the exposed copper edge cannot be guaranteed and is not required to ensure a proper bottom solder connection.
Copyright © 2012, 2013 Skyworks Solutions, Inc. All Rights Reserved.
Information in this document is provided in connection with Skyworks Solutions, Inc. (“Skyworks”) products or services. These materials, including the information contained herein, are provided by Skyworks as a
service to its customers and may be used for informational purposes only by the customer. Skyworks assumes no responsibility for errors or omissions in these materials or the information contained herein. Skyworks may change its documentation, products, services, specifications or product descriptions at any time, without notice. Skyworks makes no commitment to update the materials or information and shall have no
responsibility whatsoever for conflicts, incompatibilities, or other difficulties arising from any future changes.
No license, whether express, implied, by estoppel or otherwise, is granted to any intellectual property rights by this document. Skyworks assumes no liability for any materials, products or information provided hereunder, including the sale, distribution, reproduction or use of Skyworks products, information or materials, except as may be provided in Skyworks Terms and Conditions of Sale.
THE MATERIALS, PRODUCTS AND INFORMATION ARE PROVIDED “AS IS” WITHOUT WARRANTY OF ANY KIND, WHETHER EXPRESS, IMPLIED, STATUTORY, OR OTHERWISE, INCLUDING FITNESS FOR A PARTICULAR
PURPOSE OR USE, MERCHANTABILITY, PERFORMANCE, QUALITY OR NON-INFRINGEMENT OF ANY INTELLECTUAL PROPERTY RIGHT; ALL SUCH WARRANTIES ARE HEREBY EXPRESSLY DISCLAIMED. SKYWORKS DOES
NOT WARRANT THE ACCURACY OR COMPLETENESS OF THE INFORMATION, TEXT, GRAPHICS OR OTHER ITEMS CONTAINED WITHIN THESE MATERIALS. SKYWORKS SHALL NOT BE LIABLE FOR ANY DAMAGES, INCLUDING BUT NOT LIMITED TO ANY SPECIAL, INDIRECT, INCIDENTAL, STATUTORY, OR CONSEQUENTIAL DAMAGES, INCLUDING WITHOUT LIMITATION, LOST REVENUES OR LOST PROFITS THAT MAY RESULT FROM
THE USE OF THE MATERIALS OR INFORMATION, WHETHER OR NOT THE RECIPIENT OF MATERIALS HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
Skyworks products are not intended for use in medical, lifesaving or life-sustaining applications, or other equipment in which the failure of the Skyworks products could lead to personal injury, death, physical or environmental damage. Skyworks customers using or selling Skyworks products for use in such applications do so at their own risk and agree to fully indemnify Skyworks for any damages resulting from such improper
use or sale.
Customers are responsible for their products and applications using Skyworks products, which may deviate from published specifications as a result of design defects, errors, or operation of products outside of published parameters or design specifications. Customers should include design and operating safeguards to minimize these and other risks. Skyworks assumes no liability for applications assistance, customer product
design, or damage to any equipment resulting from the use of Skyworks products outside of stated published specifications or parameters.
Skyworks, the Skyworks symbol, and “Breakthrough Simplicity” are trademarks or registered trademarks of Skyworks Solutions, Inc., in the United States and other countries. Third-party brands and names are for
identification purposes only, and are the property of their respective owners. Additional information, including relevant terms and conditions, posted at www.skyworksinc.com, are incorporated by reference.
Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • sales@skyworksinc.com • www.skyworksinc.com
202177B • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • March 19, 2013
27