aat2552 data sheet - Skyworks Solutions, Inc.

DATA SHEET
AAT2552
Total Power Solution for Portable Applications
General Description
Features
The AAT2552 is a fully integrated 500mA battery charger, a 300mA step-down converter, and a 300mA low
dropout (LDO) linear regulator. The input voltage range
is 4V to 7.5V for the battery charger and 2.7V to 5.5V
for the step-down converter and linear regulator, making
it ideal for applications operating with single-cell lithiumion/polymer batteries.
• Battery Charger:
▪ Input Voltage Range: 4V to 7.5V
▪ Programmable Charging Current up to 500mA
▪ Highly Integrated Battery Charger
• Charging Device
• Reverse Blocking Diode
• Current Sensing
• Step-Down Converter:
▪ Input Voltage Range: 2.7V to 5.5V
▪ Output Voltage Range: 0.6V to VIN
▪ 300mA Output Current
▪ Up to 96% Efficiency
▪ 45μA Quiescent Current
▪ 1.5MHz Switching Frequency
▪ 120μs Start-Up Time
• Linear Regulator:
▪ 300mA Output Current
▪ Low Dropout: 400mV at 300mA
▪ Fast Line and Load Transient Response
▪ High Accuracy: ±1.5%
▪ 85μA Quiescent Current
• Short-Circuit, Over-Temperature, and Current Limit
Protection
• TDFN34-16 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 accuracy current and voltage regulation, charge status, and charge
termination. The charging current is programmable via
external resistor from 30mA to 500mA. In addition to
these standard features, the device offers over-voltage,
current limit, and thermal protection.
The step-down converter is a highly integrated converter
operating at a 1.5MHz switching frequency, minimizing
the size of external components while keeping switching
losses low. The output voltage ranges from 0.6V to the
input voltage.
The AAT2552 linear regulator is designed for high speed
turn-on and turn-off performance, fast transient response,
and good power supply ripple rejection. Delivering up to
300mA of load current, it includes short-circuit protection and thermal shutdown.
Applications
The AAT2552 is available in a Pb-free, thermallyenhanced TDFN34-16 package and is rated over the
-40°C to +85°C temperature range.
•
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•
Bluetooth™ Headsets
Cellular Phones
GPS
Handheld Instruments
MP3 and Portable Music Players
PDAs and Handheld Computers
Portable Media Players
Typical Application
Adapter/USB Input
Enable
ADP
INB
STAT
ENB
INA
EN_BAT
VOUTB
ENA
L1
AAT2552
RFBB1
COUTB
4.7μF
RFBB2
MODE
FBB
VOUTA
RFBA1
FBA
RFBA2
BATT+
BAT
OUTA
COUTA
System
LX
C OUT
ISET
GND
BATT-
R SET
Battery
Pack
Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com
202175B • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • March 22, 2013
1
DATA SHEET
AAT2552
Total Power Solution for Portable Applications
Pin Descriptions
Pin #
Symbol
1
EN_BAT
2
ISET
3
AGND
4
FBB
5
ENB
6
MODE
7
ENA
8
FBA
9
10
11
OUTA
INA
INB
12
LX
13
14
15
16
EP
PGND
BAT
ADP
STAT
Function
Enable pin for the battery charger. When connected to logic low, the battery charger is disabled and
consumes less than 1μA of current. When connected to logic high, the charger operates normally (pulled
down internally).
Charge current set point. Connect a resistor from this pin to ground. Refer to typical characteristics
curves for resistor selection.
Analog ground.
Feedback input for the step-down converter. This pin must be connected directly to an external resistor
divider. Nominal voltage is 0.6V.
Enable pin for the step-down converter. When connected to logic low, the step-down converter is disabled
and consumes less than 1μA of current. When connected to logic high, the converter operates normally
(pulled up internally).
Pulled down internally for automatic PWM/LL operation. Connect to logic high for forced PWM. Drive with
external clock signal to synchronize step-down converter to external clock in PWM mode.
Enable pin for the linear regulator. When connected to logic low, the regulator is disabled and consumes
less than 1μA of current. When connected to logic high, the LDO operates normally (pulled up internally).
Feedback input for the LDO. This pin must be connected directly to an external resistor divider. Nominal
voltage is 1.24V.
Linear regulator output. Connect a 2.2μF capacitor from this pin to ground.
Linear regulator input voltage. Connect a 1μF or greater capacitor from this pin to ground.
Input voltage for the step-down converter.
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.
Power ground.
Battery charging and sensing. Connect to positive terminal of Lithium-ion/polymer battery.
Input from USB port or AC wall adapter.
Open drain status pin for charger.
Exposed paddle (bottom): connect to ground directly beneath the package.
Pin Configuration
TDFN34-16
(Top View)
EN_BAT
ISET
AGND
FBB
ENB
MODE
ENA
FBA
2
1
16
2
15
3
14
4
13
5
12
6
11
7
10
8
9
STAT
ADP
BAT
PGND
LX
INB
INA
OUTA
Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com
202175B • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • March 22, 2013
DATA SHEET
AAT2552
Total Power Solution for Portable Applications
Absolute Maximum Ratings1
Symbol
Description
VINA, VINB
VADP
VLX
VFB
VEN
VX
TJ
TLEAD
Input Voltage to GND
Adapter Voltage to GND
LX to GND
FB to GND
ENA, ENB, EN_BAT to GND
BAT, ISET, STAT
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 • [email protected] • www.skyworksinc.com
202175B • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • March 22, 2013
3
DATA SHEET
AAT2552
Total Power Solution for Portable Applications
Electrical Characteristics1
VINB = 3.6V; TA = -40°C to +85°C, unless otherwise noted. Typical values are TA = 25°C.
Symbol
Description
Conditions
Min
Step-Down Converter
VIN
Input Voltage
VUVLO
UVLO Threshold
VOUT
Output Voltage Tolerance2
Output Voltage Range
VOUT
IQ
Quiescent Current
ISHDN
Shutdown Current
ILIM
P-Channel Current Limit
RDS(ON)H
High-Side Switch On Resistance
Low-Side Switch On Resistance
RDS(ON)L
ILXLEAK
LX Leakage Current
VOUT/VOUT Load Regulation
VLinereg/VIN Line Regulation
VFB
Feedback Threshold Voltage Accuracy
IFB
FB Leakage Current
FOSC
Oscillator Frequency
TS
Startup Time
TSD
Over-Temperature Shutdown Threshold
THYS
Over-Temperature Shutdown Hysteresis
VEN(L)
Enable Threshold Low
Enable Threshold High
VEN(H)
IEN
Input Low Current
Linear Regulator
VOUT
VOUT
VFB
VIN
VDO
VOUT/
VOUT*VIN
IOUT
ISC
IQ
ISHDN
Output Voltage Tolerance
V
V
mV
%
V
μA
μA
mA


μA
%
%/V
V
μA
MHz
μs
°C
°C
V
V
μA
250
3.0
VINB
90
1.0
300
0.3
0.5
VINB = 5.5V, VLX = 0 to VINB
IOUTB = 0mA to 300mA
VINB = 2.7V to 5.5V
VINB = 3.6V
VOUTB = 1.0V
1.0
0.591
0.4
0.1
0.6
0.609
0.2
1.5
120
140
15
From Enable to Output Regulation
0.6
1.4
-1.0
VINB = VENB = 5.5V
IOUTA = 1mA
to 300mA
TA = 25°C
TA = -40°C to +85°C
VINA = VOUTA + 1 to 5.0V
Output Current
Short-Circuit Current
Quiescent Current
Shutdown Current
VOUTA > 2.0V
VOUTA < 0.4V
VINA = 5V; VENA = VIN
VINA = 5V; VENA = 0V
Over-Temperature Shutdown Threshold
Over-Temperature Shutdown Hysteresis
Output Noise
Output Voltage Temperature Coefficient
Enable Threshold Low
Enable Threshold High
Enable Input Current
7.5
2.6
45
Line Regulation
TSD
THYS
eN
TC
VEN(L)
VEN(H)
IEN
Units
-3.0
0.6
No Load
VENB = GND
IOUTA = 300mA; VOUT = 3.3V
Power Supply Rejection Ratio
Max
2.7
VINB Rising
Hysteresis
IOUTB = 0 to 300mA, VINB = 2.7V to 5.5V
Output Voltage Range
Feedback Voltage Accuracy
Input Voltage
Dropout Voltage4
PSRR
Typ
IOUTA =10mA
-1.5
-2.5
1.2
1.22
VOUT + VDO3
1.0
1.24
400
1.5
2.5
3.3
1.26
5.5
650
V
V
V
mV
0.09
%/V
150
1.0
mA
mA
μA
μA
300
400
85
1kHz
10kHz
1MHz
70
50
30
140
15
95
8
eNBW = 100Hz to 100kHz
dB
0.6
1.4
VINA = VENA = 5.5V
%
1.0
°C
°C
μVRMS/Hz
ppm/°C
V
V
μA
1. The AAT2552 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.
3. VDO is defined as VIN - VOUT when VOUT is 98% of nominal.
4. For VOUT <2.3V, VDO = 2.5V - VOUT.
4
Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com
202175B • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • March 22, 2013
DATA SHEET
AAT2552
Total Power Solution 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
Reverse Leakage Current from BAT Pin
ILEAKAGE
Voltage Regulation
VBAT_EOC
End of Charge Accuracy
VMIN
Preconditioning Voltage Threshold
VRCH
Battery Recharge Voltage Threshold
Current Regulation
ICH
Charge Current Programmable Range
ICH/ICH
Charge Current Regulation Tolerance
VSET
ISET Pin Voltage
KI_A
Current Set Factor: ICH/ISET
Charging Devices
Charging Transistor On Resistance
RDS(ON)
Logic Control/Protection
Enable Threshold High
VEN(H)
VEN(L)
Enable Threshold Low
VSTAT
Output Low Voltage
ISTAT
STAT Pin Current Sink Capability
VOVP
Over-Voltage Protection Threshold
ITK/ICHG
Pre-Charge Current
ITERM/ICHG
Charge Termination Threshold Current
Conditions
Rising Edge
Min
4.0
3
150
0.5
0.3
0.4
Charge Current = 200mA
VBAT = 4.25V, VEN_BAT = GND
VBAT = 4V, ADP Pin Open
4.158
2.8
Measured from VBAT_EOC
ICHARGE = 200mA
Typ
4.20
3.0
-0.1
30
-10
Max
Units
6.5
4
V
V
mV
mA
μA
μA
1
1
2
4.242
3.2
V
V
V
500
10
mA
%
V
0.8

2
800
VADP = 5.5V
0.5
1.6
0.4
0.4
8
STAT Pin Sinks 4mA
ICH = 100mA
4.4
10
10
V
V
V
mA
V
%
%
1. The AAT2552 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.
Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com
202175B • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • March 22, 2013
5
DATA SHEET
AAT2552
Total Power Solution for Portable Applications
Typical Characteristics–Battery Charger
Constant Charging Current vs. Set Resistors
Operating Supply Current vs. RSET
(VIN = 5.0V)
(VIN = 5.0V)
10000
1000
1000
IOP (µA)
ICH (mA)
Constant Current Mode
Preconditioning Mode
100
100
10
10
1
10
100
1000
1
10
RSET (kΩ
Ω)
100
RSET (kΩ
Ω)
Operating Current vs. Temperature
Sleep Mode Current vs. Input Voltage
(VIN = 5.0V; RSET = 8.06kΩ
Ω)
(RSET = 8.06kΩ
Ω)
540
800
700
520
ISLEEP (nA)
IOP (µA)
500
480
25°C
85°C
600
500
400
300
200
460
-40°C
100
440
-50
-25
0
25
50
75
0
4.0
100
4.5
Temperature (°C)
5.0
5.5
6.0
6.5
Input Voltage (V)
Battery Charging Current vs. Battery Voltage
Constant Charging Current vs. Temperature
(RSET = 8.06kΩ
Ω)
600
215
RSET = 3.24K
210
400
ICH (mA)
ICH (mA)
500
RSET = 5.62K
300
RSET = 8.06K
200
RSET = 31.6K
190
0
2.7
2.9
3.1
3.3
3.5
VBAT (V)
6
200
195
RSET = 16.2K
100
205
3.7
3.9
4.1
4.3
185
-40
-15
10
35
60
Temperature (°C)
Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com
202175B • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • March 22, 2013
85
DATA SHEET
AAT2552
Total Power Solution for Portable Applications
Typical Characteristics–Battery Charger
End of Charge Voltage Regulation
vs. Temperature
End of Charge Battery Voltage
vs. Input Voltage
(VIN = 5V; RSET = 8.06kΩ
Ω)
4.206
4.215
4.204
RSET = 8.06kΩ
VBAT_EOC (V)
VBAT_EOC (V)
4.210
4.205
4.200
4.195
4.202
4.200
RSET = 31.6kΩ
4.198
4.196
4.190
4.185
-40
-15
10
35
60
4.194
4.5
85
5
5.5
Temperature (°C)
(RSET = 8.06kΩ
Ω)
Constant Charging Current vs. Input Voltage
(VIN = 5.62V)
4.16
310
4.14
VIN = 3.3V
305
ICH (mA)
4.12
4.10
4.08
VIN = 4V
300
VIN = 3.6V
295
290
4.06
4.04
-40
6.5
VIN (V)
Recharging Threshold Voltage vs. Temperature
VRCH (V)
6
-15
10
35
60
285
85
4
4.5
5
5.5
6
6.5
VIN (V)
Temperature (°C)
Preconditioning Charge Current vs. Temperature
(RSET = 8.06kΩ
Ω)
Preconditioning Voltage Threshold vs. Temperature
(RSET = 8.06kΩ
Ω)
3.03
20.8
3.02
3.01
VMIN (V)
ITK (mA)
20.4
20.0
3.00
2.99
19.6
2.98
19.2
-40
2.97
-15
10
35
Temperature (°C)
60
85
-40
-15
10
35
60
85
Temperature (°C)
Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com
202175B • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • March 22, 2013
7
DATA SHEET
AAT2552
Total Power Solution for Portable Applications
Typical Characteristics–Battery Charger
Enable Threshold High vs. Input Voltage
Enable Threshold Low vs. Input Voltage
(RSET = 8.06kΩ
Ω)
(RSET = 8.06kΩ
Ω)
1.1
1.2
-40°C
-40°C
1.0
VEN(L) (V)
VEN(H) (V)
1.1
1.0
0.9
0.9
0.8
85°C
0.8
0.7
4.0
4.5
5.0
5.5
VIN (V)
8
85°C
0.7
25°C
6.0
6.5
0.6
4.0
25°C
4.5
5.0
5.5
VIN (V)
Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com
202175B • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • March 22, 2013
6.0
6.5
DATA SHEET
AAT2552
Total Power Solution for Portable Applications
Typical Characteristics–Step-Down Converter
Efficiency vs. Load
DC Regulation
(VOUT = 3.3V; L = 5.6µH)
(VOUT = 3.3V; L = 5.6µH)
100
1.0
VIN = 3.6V
Output Error (%)
Efficiency (%)
90
VIN = 5.0V
80
VIN = 4.2V
70
60
50
40
0.1
1
10
100
0.5
VIN = 5.0V
0.0
VIN = 3.6V
-1.0
0.1
1000
VIN = 4.2V
-0.5
1
Output Current (mA)
10
100
1000
Output Current (mA)
Efficiency vs. Load
DC Regulation
(VOUT = 1.8V; L = 3.3µH)
(VOUT = 1.2V; L = 1.5μH)
100
1.0
VIN = 3.6V
VIN = 2.7V
Output Error (%)
Efficiency (%)
90
80
VIN = 5.0V
70
VIN = 4.2V
60
0.5
VIN = 3.6V
VIN = 5.0V
0.0
VIN = 4.2V
-0.5
VIN = 2.7V
50
-1.0
0.1
40
0.1
1
10
100
1000
1
Efficiency vs. Load
DC Regulation
(VOUT = 1.2V; L = 1.5µH)
(VOUT = 1.2V; L = 1.5μH)
100
VIN = 3.6V
Output Error (%)
Efficiency (%)
1000
1.0
90
VIN = 2.7V
VIN = 5.0V
70
60
VIN = 4.2V
50
40
0.1
100
Output Current (mA)
Output Current (mA)
80
10
1
10
Output Current (mA)
100
1000
0.5
VIN = 3.6V
VIN = 5.0V
0.0
VIN = 4.2V
-0.5
-1.0
0.1
1
10
VIN = 2.7V
100
1000
Output Current (mA)
Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com
202175B • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • March 22, 2013
9
DATA SHEET
AAT2552
Total Power Solution for Portable Applications
Typical Characteristics–Step-Down Converter
Line Regulation
Soft Start
(VOUT = 1.8V)
(VIN = 3.6V; VOUT = 1.8V; IOUT = 150mA)
Accuracy (%)
0
Enable and Output Voltage
(top) (V)
IOUT = 10mA
0.1
IOUT = 50mA
-0.1
-0.2
-0.3
IOUT = 150mA
-0.4
2.7
3.1
3.5
3.9
4.3
4.7
5.1
4
VEN
3
VOUT
2
1
0
IL
0.3
0.2
0.1
0.0
5.5
Input Voltage (V)
Inductor Current (bottom) (A)
0.2
Time (100µs/div)
Output Voltage Accuracy vs. Temperature
No Load Quiescent Current vs. Input Voltage
(VIN = 3.6V; VO = 1.8V; IOUT = 150mA)
70
1.5
1.0
85°C
60
0.5
IQ (mA)
Output Accuracy (%)
2.0
0.0
-0.5
-1.0
25°C
50
40
-40°C
-1.5
-2.0
-40
-15
10
35
60
30
2.7
85
3.1
3.5
3.9
4.3
4.7
5.1
Temperature (°°C)
Input Voltage (V)
N-Channel RDS(ON) vs. Input Voltage
P-Channel RDS(ON) vs. Input Voltage
5.5
600
1000
85°C
120°C
700
600
500
400
300
2.5
3.5
4
4.5
VIN (V)
10
5
5.5
6
100°C
120°C
400
300
25°C
200
25°C
3
85°C
500
100°C
800
RDS(ON)H (mΩ
Ω)
RDS(ON)L (mΩ
Ω)
900
100
2.5
3
3.5
4
4.5
5
VIN (V)
Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com
202175B • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • March 22, 2013
5.5
6
DATA SHEET
AAT2552
Total Power Solution for Portable Applications
Typical Characteristics–Step-Down Converter
Load Transient Response
Line Transient Response
(10mA to 300mA; VIN = 3.6V; VOUT = 1.8V; COUT = 4.7µF; C = 100pF)
(VOUT = 1.8V @ 150mA, CFF = 100pF)
1.8
1.7
1.6
IOUT
300mA
10mA
ILX
0.2
0.0
-0.2
Output Voltage (top) (V)
Output Voltage (top) (V)
VOUT
1.90
1.85
1.80
1.75
4.6
4.1
3.6
3.1
Time (25µs/div)
Output Voltage Ripple
(VIN = 3.6V; VOUT = 1.8V; IOUT = 1mA)
1.80
1.79
0.4
0.3
0.2
0.1
40
20
0
-20
0.05
0.00
-0.05
-0.10
Inductor Current (bottom) (A)
1.81
Output Voltage (AC coupled)
(top) (V)
Output Voltage Ripple
(VIN = 3.6V; VOUT = 1.8V; IOUT = 300mA)
Inductor Current (bottom) (A)
Output Voltage (AC coupled)
(top) (V)
Time (20µs/div)
Time (0.2µs/div)
Input Voltage (bottom) (V)
1.9
Load and Inductor Current
(bottom) (A)
2.0
Time (5µs/div)
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DATA SHEET
AAT2552
Total Power Solution for Portable Applications
Typical Characteristics–LDO Regulator
Quiescent Current vs. Temperature
Dropout Voltage vs. Temperature
(VIN = 5V)
0.5
120
Dropout Voltage (V)
110
IQ (µA)
100
90
80
70
60
-15
10
35
60
IL = 200mA
0.3
0.2
IL = 100mA
0.1
0.0
-40
50
-40
IL = 300mA
0.4
85
IL = 50mA
-20
0
20
Temperature (°°C)
40
60
80
100
120
Temperature (°°C)
Dropout Voltage vs. Output Current
LDO Dropout Characteristics
(EN = GND; ENLDO = VIN)
0.5
3.00
85°C
Dropout Voltage (V)
Output Voltage (V)
3.20
IOUT = 0mA
2.80
IOUT = 300mA
IOUT = 150mA
2.60
2.40
2.20
IOUT = 10mA
IOUT = 100mA
IOUT = 50mA
25°C
0.4
0.3
0.2
-40°C
0.1
0.0
2.00
2.70
0
2.80
2.90
3.00
3.10
3.20
50
100
150
200
250
300
3.30
Output Current (mA)
Input Voltage (V)
Output Voltage vs. Temperature
Enable Threshold Voltage vs. Input Voltage
(VIN = 3.6V; VO = 1.8V; IOUT = 150mA)
0.96
0.94
3.300
VENABLE (V)
Output Voltage (V)
3.301
3.299
3.298
0.92
VEN(H)
0.9
0.88
0.86
3.297
VEN(L)
0.84
3.296
-40
-15
10
35
Temperature (°°C)
12
60
85
0.82
2.7
3.1
3.5
3.9
4.3
4.7
Input Voltage (V)
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5.1
5.5
DATA SHEET
AAT2552
Total Power Solution for Portable Applications
Typical Characteristics–LDO Regulator
Line Transient Response
Load Transient Response
(IOUT = 300mA)
(1mA to 300mA; VIN = 5.0V; VOUT = 3.3V)
3.30
5.0
VIN
4.5
4.0
Output Voltage (top) (V)
Output Voltage (top) (V)
VOUT
3.6
3.4
3.2
VOUT
0.4
IL
0.2
0.0
-0.2
Time (100µs/div)
Time (100µs/div)
Turn-On Time From Enable
(VIN = 4.2V; IOUT = 300mA)
(VIN = 4.2V; IOUT = 300mA)
VEN = 2V/div
VOUT = 1V/div
Time (50µs/div)
Enable and Output Voltage
Turn-Off Response Time
Enable and Output Voltage
Output Current (bottom) (A)
3.35
Input Voltage (bottom) (V)
3.40
VEN = 2V/div
VOUT = 1V/div
Time (100µs/div)
LDO Output Noise
(COUT = 4.7µF; IOUT = 10mA; RLOAD = 330; 98.33µVrms)
nVrms/sqrt (Hz)
10000
1000
100
10
0.01
0.1
1
10
100
1000
Frequency (kHz)
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DATA SHEET
AAT2552
Total Power Solution for Portable Applications
Functional Block Diagram
Reverse Blocking
ADP
BAT
Current Compare
CV/Pre-Charge
Constant Current
ISET
Charge
Control
UVLO
STAT
FBB
Charge Status
INB
EN_BAT
Err.
Amp
DH
.
Voltage
Reference
ENB
LX
Logic
DL
Input
MODE
From
Charger Section
PGND
Over-Temperature
Protection
INA
OUTA
Active Feedback
Control
Over-Current
Protection
FBA
+
ENA
Fast Start
Control
Err.
Amp
-
Voltage
Reference
AGND
Functional Description
The AAT2552 is a high performance power man-agement
IC comprised of a lithium-ion/polymer battery charger, a
step-down converter, and a linear regulator. The linear
regulator is designed for high-speed turn-on and fast
transient response, and good power supply ripple rejection. The step-down converter operates in both fixed and
variable frequency modes for high efficiency performance.
The switching frequency is 1.5MHz, minimizing the size of
the inductor. In light load conditions, the device enters
power-saving mode; the switching frequency is reduced
and the converter consumes 45μA of current, making it
ideal for battery-operated applications.
Battery Charger
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
14
adapter/USB input voltage range from 4V to 7.5V. 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.
Switch-Mode Step-Down Converter
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 con-
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DATA SHEET
AAT2552
Total Power Solution for Portable Applications
sumes 45μA of current, making it ideal for batteryoperated applications. The output voltage is programmable from VIN to as low as 0.6V. Power devices are
sized for 300mA current capability while maintaining
over 96% 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.
The AAT2552 synchronous step-down converter can be
synchronized to an external clock signal applied to the
MODE pin.
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.
Linear Regulator
Current Limit / Over-Temperature Protection
The advanced circuit design of the linear regulator has
been specifically optimized for very fast start-up. This
proprietary CMOS LDO has also been tailored for superior transient response characteristics. These traits are
particularly important for applications that require fast
power supply timing.
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 high-speed turn-on capability is enabled through
implementation of a fast-start control circuit which
accelerates the power-up behavior of fundamental control and feedback circuits within the LDO regulator. The
LDO regulator output has been specifically optimized to
function with low-cost, low-ESR ceramic capacitors;
however, the design will allow for operation over a wide
range of capacitor types.
The regulator comes with complete short-circuit and thermal protection. The combination of these two internal
protection circuits gives a comprehensive safety system
to guard against extreme adverse operating conditions.
The regulator features an enable/disable function. This
pin (ENA) is active high and is compatible with CMOS
logic. The LDO regulator will go into the disable shutdown mode when the voltage on the ENA pin falls below
0.6V. If the enable function is not needed in a specific
application, it may be tied to INA to keep the LDO regulator in a continuously on state.
Under-Voltage Lockout
The AAT2552 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
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.
Control Loop
The AAT2552 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.
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
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DATA SHEET
AAT2552
Total Power Solution for Portable Applications
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.
Pre-conditioning continues until the battery voltage
reaches VMIN (see Figure 1). At this point, the charger
begins constant-current charging. The current level for
this mode is programmed using a single resistor from
the ISET pin to ground. Programmed current can be set
from a minimum 15mA up to a maximum of 500mA.
Constant current charging will continue until the battery
Preconditioning
Trickle Charge
Phase
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.
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.
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.
16
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DATA SHEET
AAT2552
Total Power Solution 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 BAT_EOC > VBAT
No
Voltage Phase Test
IBAT > ITERM
No
Charge Completed
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DATA SHEET
AAT2552
Total Power Solution for Portable Applications
Application Information
Soft Start / Enable
stant current levels from 30mA to 500mA may be set by
selecting the appropriate resistor value from Table 1.
Normal ICHARGE (mA)
Set Resistor Value R1 (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
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.
Separate ENA and ENB inputs are provided to independently enable and disable the LDO and step-down converter, respectively. This allows sequencing of the LDO
and step-down outputs during startup.
The step-down converter is enabled when the ENB pin is
pulled high. Soft start increases the inductor current
limit point in discrete steps when the input voltage or
ENB input is applied. It limits the current surge seen at
the input and eliminates output voltage overshoot.
When pulled low, the ENB input forces the AAT2552 into
a low-power, non-switching state. The step-down converter input current during shutdown is less than 1μA.
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 7.5V 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 con-
18
1000
ICH (mA)
The LDO is enabled when the ENA pin is pulled high.
The control and feedback circuits have been optimized
for high-speed, monotonic turn-on characteristics.
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 AAT2552 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
Status
No battery charging activity
Battery charging via adapter or USB port
Charging completed
OFF
ON
OFF
Table 2: LED Status Indicator.
The LED should be biased with as little current as necessary to create reasonable illumination; therefore, a bal-
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DATA SHEET
AAT2552
Total Power Solution for Portable Applications
Figure 3 shows the relationship of maximum power dissipation and ambient temperature of the AAT2552.
3.00
2.50
PD(MAX) (mW)
last resistor should be placed between the LED cathode
and the STAT pin. LED current consumption will add to
the overall thermal power budget for the device 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.
The required ballast resistor values can be estimated
using the following formulas:
2.00
1.50
1.00
0.50
R6 =
(VADP - VF(LED))
ILED
0.00
0
20
40
60
80
100
TA (°°C)
Example:
Figure 3: Maximum Power Dissipation.
(5.5V - 2.0V)
= 1.75kΩ
R6 =
2mA
Note: Red LED forward voltage (VF) is typically 2.0V @
2mA.
Thermal Considerations
The AAT2552 is offered in a TDFN34-16 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) =
(TJ(MAX) - TA)
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)
Next, the power dissipation of the battery charger can be
calculated by the following equation:
PD = [(VADP - VBAT) · ICH + (VADP · IOP)]
Where:
PD
VADP
VBAT
ICH
IOP
=
=
=
=
Total Power Dissipation by the Device
ADP/USB Voltage
Battery Voltage as Seen at the BAT Pin
Constant Charge Current Programmed for the
Application
= 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
AAT2552
Total Power Solution for Portable Applications
Capacitor Selection
500
450
ICH(MAX) (mA)
Linear Regulator Input Capacitor (C6)
TA = 25°C
400
350
300
TA = 60°C
250
TA = 45°C
200
150
TA = 85°C
100
50
0
4.25
4.5
4.75
5
5.25
5.5
5.75
6
6.25
6.5
6.75
7
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
+ (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:
An input capacitor greater than 1μF will offer superior
input line transient response and maximize power supply ripple rejection. Ceramic, tantalum, or aluminum
electrolytic capacitors may be selected for CIN. There is
no specific capacitor ESR requirement for CIN. However,
for 300mA LDO regulator output operation, ceramic
capacitors are recommended for CIN due to their inherent capability over tantalum capacitors to withstand
input current surges from low impedance sources such
as batteries in portable devices.
Battery Charger Input Capacitor (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 (C6)
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 =
2
O
PTOTAL = I
· 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 TDFN34-16
package which is 50°C/W.
V ⎞
VO ⎛
· 1- O
VIN ⎝
VIN ⎠
⎛ VPP
⎞
- ESR · FS
⎝ IO
⎠
VO ⎛
V ⎞
1
· 1 - O = for VIN = 2 · VO
VIN ⎝
VIN ⎠
4
CIN(MIN) =
1
⎛ VPP
⎞
- ESR · 4 · FS
⎝ IO
⎠
TJ(MAX) = PTOTAL · ΘJA + TAMB
Always examine the ceramic capacitor DC voltage coeffi-
20
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DATA SHEET
AAT2552
Total Power Solution for Portable Applications
cient 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
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) =
IO
2
The term appears in both the input voltage ripple and
input capacitor RMS current equations and is a maximum when VO is twice VIN. This is why the input voltage
ripple and the input capacitor RMS current ripple are a
maximum at 50% duty cycle.
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 (C6) can be
seen in the evaluation board layout in Figure 7.
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.
The linear regulator and the step-down convertor share
the same input capacitor on the evaluation board.
Linear Regulator Output Capacitor (C5)
For proper load voltage regulation and operational stability, a capacitor is required between OUT and GND. The
COUT capacitor connection to the LDO regulator ground
pin should be made as directly as practically possible for
maximum device performance. Since the regulator has
been designed to function with very low ESR capacitors,
ceramic capacitors in the 1.0μF to 10μF range are recommended for best performance. Applications utilizing
the exceptionally low output noise and optimum power
supply ripple rejection should use 2.2μF or greater for
COUT. In low output current applications, where output
load is less than 10mA, the minimum value for COUT can
be as low as 0.47μF.
Battery Charger Output Capacitor (C2)
The battery charger of the AAT2552 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 AAT2552 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 (C3)
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
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DATA SHEET
AAT2552
Total Power Solution for Portable Applications
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 hot-spot 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 current down slope
meets the internal slope compensation requirements.
The internal slope compensation for the AAT2552 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=
22
For most designs, the step-down converter operates with
inductor values from 1μH to 4.7μH. Table 6 displays inductor values for the AAT2552 for various output voltages.
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.
Adjustable Output Voltage
for the Step-down Converter
Resistors R2 and R3 of Figure 5 program the output of
the step down converter and 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 R3 is 59k.
Decreased resistor values are necessary to maintain
noise immunity on the FBB pin, resulting in increased
quiescent current. Table 3 summarizes the resistor values for various output voltages.
⎛ VOUT ⎞
⎛ 3.3V ⎞
R2 = V
-1 · R3 = 0.6V - 1 · 59kΩ = 267kΩ
⎝ REF ⎠
⎝
⎠
With enhanced transient response for extreme pulsed
load application, an external feed-forward capacitor (C8
in Figure 5) can be added.
0.75 ⋅ VO 0.75 ⋅ 1.8V
A
=
= 0.45
L
3.0µH
µsec
0.75 ⋅ VO
=
m
µsec
0.75 ⋅ VO
≈ 1.67 A ⋅ VO
A
0.45A µsec
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DATA SHEET
AAT2552
Total Power Solution for Portable Applications
VOUT (V)
R3 = 59k
R2 (k)
R3 = 221k
R2 (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 3: Adjustable Resistor Values For
Step-Down Converter.
Adjustable Output Voltage for the LDO
The output voltage for the LDO can be programmed by
an external resistor divider network.
As shown below, the selection of R4 and R5 is a straightforward matter. R5 is chosen by considering the tradeoff
between the feedback network bias current and resistor
value. Higher resistor values allow stray capacitance to
become a larger factor in circuit performance whereas
lower resistor values increase bias current and decrease
efficiency. To select appropriate resistor values, first
choose R5 such that the feedback network bias current
is reasonable. Then, according to the desired VOUT, calculate R4 according to the equation below. An example
calculation follows.
R4 =
(R5 = 59kΩ)
VOUT (V)
R4 (kΩ)
3.3
2.8
2.5
2.0
1.8
1.5
97.6
75.0
60.4
36.5
26.7
12.4
Table 4: Adjustable Resistor Values for the LDO.
Printed Circuit Board
Layout Considerations
For the best results, it is recommended to physically
place the battery pack as close as possible to the
AAT2552 BAT pin. To minimize voltage drops on the PCB,
keep the high current carrying traces adequately wide.
Refer to the AAT2552 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.
3.
⎛ VOUT ⎞
- 1 · R5
⎝ VREF ⎠
An R5 value of 59kΩ is chosen, resulting in a small feedback network bias current of 1.24V/59kΩ ≈ 21μA. The
desired output voltage is 1.8V. From this information, R4
is calculated from the equation below. The result is R4 =
26.64kΩ. Since 26.64kΩ is not a standard 1%-value,
26.7kΩ is selected. From this example calculation, for
VOUT = 1.8V, use R5 = 59kΩ and R4 = 26.7kΩ. Example
output voltages and corresponding resistor values are
provided in Table 4.
R4 Standard 1% Values
4.
5.
The input capacitors (C1, C6) should connect as
closely as possible to ADP, INA, and INB. It is possible to use two input capacitors for INA and INB.
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.
The feedback pin 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 FBB
pin 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 PGND 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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23
DATA SHEET
AAT2552
Total Power Solution for Portable Applications
JP1
2 1
EN_BAT
3 2 1
Power Selection
BAT
ADP
D1
RED
LED
C1
10μF
R6
1.5K
Sync/Mode
1
6
L1
C4
100pF
R2
(Optional)
C3
4.7μF
1
2
EN_LDO
JP3
U1
15
16
VoB
JP2
C6
10μF
(at bottom layer)
12
ADP
STAT
EN_BAT
MODE
LX
INA
INB
ENA
ENB
10
1
11
2
7
5
BAT
14
4
FBB
ISET
2
3
AGND
OUTA
9
13
PGND
FBA
8
EN_BUCK
VoA
C2
10μF
R1
8.06K
R4
R3
59k
C5
4.7μF
R5
59k
VOUTB (V) R2 (Ω)
0.6
13
1.2
1.8
2.5
3.0
3.3
L1
R2 short, R3 open
9.2K
59K
118K
187K
237K
267K
1.5μH (CDRH2D09/HP; DCR 88mΩ; 730mA @ 20°C)
2.2μH (CDRH2D09/HP; DCR 115mΩ; 600mA @ 20°C)
3.0μH (CDRH2D09/HP; DCR 150mΩ; 470mA @ 20°C)
3.9μH (CDRH2D09/HP; DCR 180mΩ; 450mA @ 20°C)
4.7μH (CDRH2D09/HP; DCR 230mΩ; 410mA @ 20°C)
5.6μH (CDRH2D09/HP; DCR 260mΩ; 370mA @ 20°C)
VOUTA (V)
1.24
1.5
1.8
2.0
2.5
2.8
3.0
R4 (Ω)
R4 short, R5 open
12.4K
26.7K
36.5K
60.4K
75.0K
97.6K
Figure 5: AAT2552 Evaluation Board Schematic.
Figure 6: AAT2552 Evaluation Board
Top Side Layout.
24
Figure 7: AAT2552 Evaluation Board
Bottom Side Layout.
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DATA SHEET
AAT2552
Total Power Solution for Portable Applications
Component
Part Number
Description
Manufacturer
U1
C1, C2
C3, C5
C6
C4
L1
R6
R1
R2
R3, R5
R4
JP1, JP2, JP3, JP4
D1
AAT2552IRN
ECJ-1VB0J106M
GRM188R60J475KE19
GRM319R61A106KE19
GRM1886R1H101JZ01J
CDRH2D09
Chip Resistor
Chip Resistor
Chip Resistor
Chip Resistor
Chip Resistor
PRPN401PAEN
CMD15-21SRC/TR8
Total Power Solution for Portable Applications
CER 10μF 6.3V X5R 0603
CER 4.7μF 6.3V X5R 0603
CER 10μF 10V X5R 1206
CER 100pF 50V 5% R2H 0603
Shielded SMD, 3x3x1mm
1.5KΩ, 5%, 1/4W 0603
8.06KΩ, 1%, 1/4W 0603
118KΩ, 1%, 1/4W 0603
59KΩ, 1%, 1/4W 0603
60.4KΩ, 1%, 1/4W 0603
Conn. Header, 2mm zip
Red LED 1206
Skyworks
Panansonic
Murata
Murata
Murata
Sumida
Vishay
Vishay
Vishay
Vishay
Vishay
Sullins Electronics
Chicago Miniature Lamp
Table 5: AAT2552 Evaluation Board Component Listing.
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25
DATA SHEET
AAT2552
Total Power Solution for Portable Applications
Step-Down Converter Design Example (to be updated)
Specifications
VO
VIN
FS
TAMB
=
=
=
=
1.8V @ 250mA, Pulsed Load ILOAD = 200mA
2.7V to 4.2V (3.6V nominal)
1.5MHz
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.
⎛
VO
V ⎞
1.8V
1.8V ⎞
⎛
⋅ 1- O =
⋅ 1= 228mA
L1 ⋅ FS ⎝
VIN⎠ 3.0µH ⋅ 1.5MHz ⎝
4.2V ⎠
ΔIL1 =
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
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
26
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DATA SHEET
AAT2552
Total Power Solution for Portable Applications
AAT2552 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
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DATA SHEET
AAT2552
Total Power Solution for Portable Applications
Output Voltage
VOUTB (V)
R3 = 59kΩ
R3 (kΩ)
R3 = 221kΩ
R1 (kΩ)
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
3.3
R2 short, R3 open
19.6
29.4
39.2
49.9
59.0
68.1
78.7
88.7
118
124
137
187
237
267
R2 short, R3 open
75
113
150
187
221
261
301
332
442
464
523
715
887
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
4.9
5.6
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
NR3010T1R5N
NR3010T2R2M
NR3010T3R3M
NR3010T4R7M
MIPWT3226D-1R5
MIPWT3226D-2R2
MIPWT3226D-3R0
MIPWT3226D-4R2
1.5
2.2
2.5
3.0
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
3.0
4.2
730
600
530
470
450
410
370
900
780
600
500
1200
1100
870
750
1200
1100
1000
900
110
144
150
194
225
287
325
68
98
123
170
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, R3 = 221k.
28
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DATA SHEET
AAT2552
Total Power Solution for Portable Applications
Manufacturer
Part Number
Value (μF)
Voltage Rating
Temp. Co.
Case Size
Murata
Murata
Murata
Murata
Murata
Murata
GRM21BR61A106KE19
GRM188R60J475KE19
GRM188R61A225KE34
GRM188R60J225KE19
GRM188R61A105KA61
GRM185R60J105KE26
10
4.7
2.2
2.2
1.0
1.0
10
6.3
10
6.3
10
6.3
X5R
X5R
X5R
X5R
X5R
X5R
0805
0603
0603
0603
0603
0603
Table 8: Surface Mount Capacitors.
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29
DATA SHEET
AAT2552
Total Power Solution for Portable Applications
Ordering Information
Package
Marking1
Part Number (Tape and Reel)2
TDFN34-16
UVXYY
AAT2552IRN-CAE-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
Code
Adjustable
(0.6)
0.9
Adjustable
(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
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.
30
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DATA SHEET
AAT2552
Total Power Solution for Portable Applications
Package Information1
TDFN34-16
3.000 ± 0.050
1.600 ± 0.050
Detail "A"
3.300 ± 0.050
4.000 ± 0.050
Index Area
0.350 ± 0.100
Top View
0.230 ± 0.050
Bottom View
C0.3
(4x)
0.050 ± 0.050
0.450 ± 0.050
0.850 MAX
Pin 1 Indicator
(optional)
0.229 ± 0.051
Side View
Detail "A"
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
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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 • [email protected] • www.skyworksinc.com
202175B • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • March 22, 2013
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