SKYWORKS AAT2554IRN-CAW-T1

DATA SHEET
AAT2554
Total Power Solution for Portable Applications
General Description
Features
The AAT2554 is a fully integrated 500mA battery charger, a 250mA step-down converter, and a 300mA low
dropout (LDO) linear regulator. The input voltage range
is 4V to 6.5V for the battery charger and 2.7V to 5.5V
for the 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 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
• Linear Regulator:
▪ 300mA Output Current
▪ Low Dropout: 400mV at 300mA
▪ Fast Line and Load Transient Response
▪ High Accuracy: ±1.5%
▪ 70μA Quiescent Current
• Short-Circuit, Over-Temperature, and Current Limit
Protection
• 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 15mA 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. It has independent input and enable pins. The
output voltage ranges from 0.6V to the input voltage.
The AAT2554 linear regulator is designed for fast transient response and good power supply ripple rejection.
Designed for 300mA of load current, it includes shortcircuit protection and thermal shutdown.
Applications
The AAT2554 is available in a Pb-free, thermallyenhanced TDFN34-16 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
Enable
ADP
VINB
STAT
ENB
VINA
EN_BAT
L= 3.0μH
LX
ENA
AAT2554
RFB2
BATT+
BAT
RFB1
C OUTB
System
VOUTB
FB
VOUTA
OUTA
C OUTA
C OUT
ISET
GND
BATTR SET
Battery
Pack
Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com
202176B • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • March 19, 2013
1
DATA SHEET
AAT2554
Total Power Solution for Portable Applications
Pin Descriptions
Pin #
Symbol
1
FB
2, 10, 12, 14
GND
3
ENB
4
5
VINA
OUTA
6
EN_BAT
7
ISET
8
9
11
BAT
STAT
ADP
13
ENA
15
LX
16
EP
VINB
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 consumes less than 1μA of current. When connected to logic high, the converter
resumes normal operation.
Linear regulator input voltage. Connect a 1μF or greater capacitor from this pin to ground.
Linear regulator output. Connect a 2.2μF capacitor from this pin to ground.
Enable pin for the battery charger. When connected to logic low, the battery charger is disabled
and consumes less than 1μA of current. When connected to logic high, the charger resumes normal operation.
Charge current set point. Connect a resistor from this pin to ground. Refer to the Typical Characteristics curves for resistor selection.
Battery charging and sensing.
Charge status input. Open drain status output.
Input for USB/adapter charger.
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 regulator resumes normal
operation.
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
TDFN34-16
(Top View)
FB
GND
ENB
VINA
OUTA
EN_BAT
ISET
BAT
2
1
16
2
15
3
14
4
13
5
12
6
11
7
10
8
9
VINB
LX
GND
ENA
GND
ADP
GND
STAT
Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com
202176B • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • March 19, 2013
DATA SHEET
AAT2554
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
202176B • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • March 19, 2013
3
DATA SHEET
AAT2554
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
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
VINB Rising
Hysteresis
VINB Falling
IOUTB = 0 to 250mA, VINB = 2.7V
to 5.5V
Max
Units
5.5
2.7
V
V
mV
V
3.0
%
VINB
V
μA
μA
mA


μA
200
1.8
-3.0
0.6
No Load
ENB = GND
30
1.0
600
0.59
0.42
VINB = 5.5V, VLX = 0 to VINB
Line Regulation
VINB = 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
VINB = 3.6V
VOUTB = 1.0V
1.0
0.2
0.591
0.6
%/V
0.609
0.2
1.5
100
140
15
From Enable to Output Regulation
0.6
VINB = VENB = 5.5V
1.4
-1.0
1.0
V
μA
MHz
μs
°C
°C
V
V
μA
1. The AAT2554 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 • [email protected] • www.skyworksinc.com
202176B • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • March 19, 2013
DATA SHEET
AAT2554
Total Power Solution for Portable Applications
Electrical Characteristics1
VINA = VOUT(NOM) + 1V for VOUT options greater than 1.5V. IOUT = 1mA, COUT = 2.2μF, CIN = 1μF, TA = -40°C to +85°C,
unless otherwise noted. Typical values are TA = 25°C.
Symbol
Description
Conditions
Min
Typ
Max
Units
1.5
2.5
%
5.5
V
600
mV
Linear Regulator
VOUT
Output Voltage Tolerance
VIN
Input Voltage
IOUTA = 1mA
to 300mA
TA = 25°C
TA = -40°C to +85°C
-1.5
-2.5
VOUT
+ VDO2
VDO
VOUT/
VOUT*VIN
Dropout Voltage
IOUTA = 300mA
400
Line Regulation
VINA = VOUTA + 1 to 5.0V
0.09
%/V
VOUT(Line)
Dynamic Line Regulation
2.5
mV
VOUT(Load)
IOUT
ISC
IQ
ISHDN
Dynamic Load Regulation
Output Current
Short-Circuit Current
Quiescent Current
Shutdown Current
60
mV
mA
mA
μA
μA
3
PSRR
Power Supply Rejection Ratio
TSD
THYS
eN
TC
TEN_DLY
VEN(L)
VEN(H)
IEN
Over-Temperature Shutdown Threshold
Over-Temperature Shutdown Hysteresis
Output Noise
Output Voltage Temperature Coefficient
Enable Time Delay
Enable Threshold Low
Enable Threshold High
Enable Input Current
IOUTA = 300mA, VINA = VOUTA + 1 to VOUTA
+ 2, TR/TF = 2μs
IOUTA = 1mA to 300mA, TR <5μs
VOUTA > 1.2V
VOUTA < 0.4V
VINA = 5V; ENA = VIN
VINA = 5V; ENA = 0V
1kHz
10kHz
IOUTA =10mA
1MHz
300
600
70
125
1.0
65
45
43
145
12
250
22
15
dB
0.6
1.5
VENA = 5.5V
1.0
°C
°C
μVRMS
ppm/°C
μs
V
V
μA
1. The AAT2554 is guaranteed to meet performance specifications over the -40°C to +85°C operating temperature range and is assured by design, characterization, and correlation with statistical process controls.
2. VDO is defined as VIN - VOUT when VOUT is 98% of nominal.
3. For VOUT <2.3V, VDO = 2.5V - VOUT.
Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com
202176B • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • March 19, 2013
5
DATA SHEET
AAT2554
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
Battery Charger
Operation
VADP
Adapter Voltage Range
VUVLO
Under-Voltage Lockout (UVLO)
UVLO Hysteresis
Operating Current
IOP
ISHUTDOWN
Shutdown Current
ILEAKAGE
Reverse Leakage Current from BAT Pin
Voltage Regulation
End of Charge Accuracy
VBAT_EOC
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
VEN(H)
Enable Threshold High
VEN(L)
Enable Threshold Low
Output Low Voltage
VSTAT
ISTAT
STAT Pin Current Sink Capability
VOVP
Over-Voltage Protection Threshold
ITK/ICHG
Pre-Charge Current
Charge Termination Threshold Current
ITERM/ICHG
Conditions
Rising Edge
Min
Typ
4.0
3
150
0.5
0.3
0.4
Charge Current = 200mA
VBAT = 4.25V, EN_BAT = GND
VBAT = 4V, ADP Pin Open
4.158
2.85
Measured from VBAT_EOC
4.20
0.5
3.0
-0.1
15
Max
Units
6.5
4
V
V
mV
mA
μA
μA
1
1
2
4.242
3.15
500
mA
%
V
1.1

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 AAT2554 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.
6
Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com
202176B • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • March 19, 2013
DATA SHEET
AAT2554
Total Power Solution 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)
Efficiency vs. Load
DC Load Regulation
(VOUT = 1.2V; L = 1.5µH)
(VOUT = 1.2V; L = 1.5µH)
Output Error (%)
Efficiency (%)
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
Output Current (mA)
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)
1000
1.0
VIN = 2.7V
90
30
100
Output Current (mA)
100
80
VIN = 5.0V
VIN = 4.2V
-1.0
0.1
1000
VIN = 5.5V
IOUT = 0mA
0.4
0.3
IOUT = 50mA
0.2
IOUT = 150mA
0.1
0.0
-0.1
IOUT = 10mA
IOUT = 250mA
-0.2
-0.3
2.5
3.0
3.5
4.0
4.5
5.0
5.5
6.0
Input Voltage (V)
Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com
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7
DATA SHEET
AAT2554
Total Power Solution for Portable Applications
Typical Characteristics – Step-Down Converter
Output Voltage Error vs. Temperature
Switching Frequency Variation
vs. Temperature
(VINB = 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
30
25°C
25
-40°C
20
15
3.1
3.9
4.3
4.7
5.1
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
2.5
3.5
P-Channel RDS(ON) vs. Input Voltage
RDS(ON)L (mΩ
Ω)
RDS(ON)H (mΩ
Ω)
85°C
Input Voltage (V)
400
8
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
Input Voltage (V)
Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com
202176B • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • March 19, 2013
5.5
6.0
DATA SHEET
AAT2554
Total Power Solution 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
4.5
1.65
VIN
4.0
1.55
3.5
1.50
3.0
Time (25µs/div)
20
0
0.07
0.06
VO
0.05
-20
0.04
-40
0.03
-60
0.02
-80
-100
0.01
IL
Inductor Current
(bottom) (A)
VO
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
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)
Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com
202176B • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • March 19, 2013
9
DATA SHEET
AAT2554
Total Power Solution 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
75
100
(RSET = 8.06kΩ
Ω)
210
220
208
210
205
VBAT = 3.3V
ICH (mA)
ICH (mA)
50
Constant Charging Current vs. Temperature
(RSET = 8.06kΩ
Ω)
200
190
VBAT = 3.6V
VBAT = 4V
203
200
198
195
180
193
4
4.25
4.5
4.75
5
5.25
5.5
VADP (V)
10
25
Temperature (°C)
VADP (V)
170
0
5.75
6
6.25
6.5
190
-50
-25
0
25
50
Temperature (°C)
Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com
202176B • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • March 19, 2013
75
100
DATA SHEET
AAT2554
Total Power Solution for Portable Applications
Typical Characteristics – Battery Charger
Operating Current vs. Temperature
Preconditioning Threshold Voltage
vs. Temperature
(RSET = 8.06kΩ
Ω)
(RSET = 8.06kΩ
Ω)
550
3.03
3.02
450
VMIN (V)
IOP (µA)
500
400
3.01
3
2.99
350
2.98
300
-50
-25
0
25
50
75
2.97
-50
100
-25
0
Temperature (°C)
(RSET = 8.06kΩ
Ω)
ITRICKLE (mA)
ITRICKLE (mA)
20.4
20.2
20.0
19.8
19.6
40
RSET = 5.36kΩ
30
RSET = 8.06kΩ
20
25
50
75
0
100
4
4.2
4.4
4.6
5
5.2
5.4
5.6
5.8
6
6.2
6.4
VADP (V)
Recharging Threshold Voltage
vs. Temperature
Sleep Mode Current vs. Supply Voltage
(RSET = 8.06kΩ
Ω)
800
4.18
700
4.16
85°C
600
ISLEEP (nA)
4.14
4.12
4.10
4.08
500
400
300
4.06
200
4.04
100
-50
4.8
Temperature (°C)
(RSET = 8.06kΩ
Ω)
4.02
RSET = 31.6kΩ
RSET = 16.2kΩ
10
19.4
VRCH (V)
RSET = 3.24kΩ
50
0
100
60
20.6
-25
75
Preconditioning Charge Current
vs. Supply Voltage
20.8
-50
50
Temperature (°C)
Preconditioning Charge Current
vs. Temperature
19.2
25
-25
0
25
50
Temperature (°C)
75
100
-40°C
25°C
0
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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DATA SHEET
AAT2554
Total Power Solution 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
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)
12
-40°C
1
-40°C
VEN(L) (V)
VEN(H) (V)
1.1
5.75
6
6.25
6.5
4
4.25
4.5
4.75
5
5.25
5.5
5.75
6
VADP (V)
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6.25
6.5
DATA SHEET
AAT2554
Total Power Solution for Portable Applications
Typical Characteristics – LDO Regulator
Dropout Voltage vs. Temperature
LDO Dropout Characteristics
(EN = GND; ENLDO = VIN)
3.20
IL = 300mA
480
420
Output Voltage (V)
Dropout Voltage (mV)
540
360
300
IL = 100mA
IL = 150mA
240
180
120
60
-40 -30 -20 -10 0
2.80
IOUT = 300mA
IOUT = 150mA
2.60
2.40
2.20
IL = 50mA
0
IOUT = 0mA
3.00
IOUT = 10mA
2.00
2.70
10 20 30 40 50 60 70 80 90 100 110 120
2.80
IOUT = 100mA
IOUT = 50mA
2.90
Temperature (°C)
Dropout Voltage vs. Output Current
3.20
3.30
90
80
Ground Current (µA)
450
Dropout Voltage (mV)
3.10
Ground Current vs. Input Voltage
500
400
350
300
85°C
250
200
25°C
150
-40°C
100
50
0
0
50
100
150
200
250
70
60
IOUT = 300mA
50
IOUT = 150mA
IOUT = 50mA
40
IOUT = 0mA
30
IOUT = 10mA
20
10
0
300
2
2.5
3
3.5
4
4.5
Output Current (mA)
Input Voltage (V)
Quiescent Current vs. Temperature
Output Voltage vs. Temperature
5
1.203
100
90
1.202
80
Output Voltage (V)
Quiescent Current (µA)
3.00
Input Voltage (V)
70
60
50
40
30
20
10
0
-40 -30 -20 -10
0
10 20 30 40 50 60 70 80 90 100 110 120
Temperature (°C)
1.201
1.200
1.199
1.198
1.197
1.196
-40 -30 -20 -10
0
10 20
30
40
50 60
70 80
90 100
Temperature (°C)
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DATA SHEET
AAT2554
Total Power Solution for Portable Applications
Typical Characteristics – LDO Regulator
LDO Turn-On Time from Enable
LDO Initial Power-Up Response Time
(VIN Present)
(CBYP = 10nF; EN = GND; ENLDO = VIN)
Enable Voltage (top) (V)
4
5
3
4
2
3
1
2
0
Output Voltage (bottom) (V)
VENLDO (5V/div)
6
1
0
VOUT (1V/div)
Time (5µs/div)
Time (400µs/div)
Line Transient Response
Turn-Off Response Time
(I = 100mA)
6
3.04
Input Voltage (V)
4
3.02
3
3.01
2
3.00
VOUT
1
VOUT (1V/div)
3.03
VIN
2.99
0
2.98
Time (50µs/div)
Time (100µs/div)
Load Transient Response
2.80
300
2.75
200
2.70
100
2.65
2.60
0
IOUT
-100
Time (100µs/div)
14
Output Voltage (V)
400
VOUT
3.0
800
2.9
700
2.8
2.7
600
VOUT
500
2.6
400
2.5
300
200
2.4
2.3
IOUT
100
2.2
0
2.1
-100
Time (10µs/div)
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Output Current (mA)
2.85
500
Output Current (mA)
Output Voltage (V)
2.90
Load Transient Response 300mA
Output Voltage (V)
5
VEN (5V/div)
DATA SHEET
AAT2554
Total Power Solution for Portable Applications
Typical Characteristics – LDO Regulator
Over-Current Protection
VEN(L) and VEN(H) vs. VIN
Enable Threshold Voltage (V)
(EN = GND; ENLDO = VIN)
Output Current (mA)
1200
1000
800
600
400
200
0
-200
Time (50ms/div)
1.250
1.225
1.200
VEN(H)
1.175
1.150
1.125
VEN(L)
1.100
1.075
1.050
2.5
3.0
3.5
4.0
4.5
5.0
5.5
Input Voltage (V)
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15
DATA SHEET
AAT2554
Total Power Solution for Portable Applications
Functional Block Diagram
Reverse Blocking
BAT
ADP
STAT
-
Constant
Current
ISET
Charge
Control
+
+
-
VREF
OverTemperature
Protection
EN_BAT
UVLO
VINB
DH
VINA
Err.
Amp.
LX
Logic
VREF
DL
OverCurrent
Protection
ENB
FB
+
VREF
OUTA
ENA
GND
Functional Description
The AAT2554 is a high performance power management
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 30μA of
current, making it ideal for battery-operated applications.
Battery Charger
The battery charger is designed for single-cell lithiumion/polymer batteries using a constant current and constant voltage algorithm. The battery charger operates
from the adapter/USB input voltage range from 4V to
16
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.
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 consumes 30μA of current, making it ideal for batteryoperated applications. The output voltage is program-
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DATA SHEET
AAT2554
Total Power Solution for Portable Applications
mable from VIN to as low as 0.6V. Power devices are sized
for 250mA current capability while maintaining over
90% efficiency at full load. Light load efficiency is maintained at greater than 80% down to 1mA of load current.
A high-DC gain error amplifier with internal compensation controls the output. It provides excellent transient
response and load/line regulation.
Linear Regulator
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.
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. To assure the LDO regulator will switch on, the ENA
turn-on control level must be greater than 1.5V. The LDO
regulator will go into the disable shutdown mode when
the voltage on the ENA pin falls below 0.6V. If the enable
function is not needed in a specific application, it may be
tied to VINA to keep the LDO regulator in a continuously
on state.
Under-Voltage Lockout
The AAT2554 has internal circuits for UVLO and power on
reset features. If the ADP supply voltage drops below the
UVLO threshold, the battery charger will suspend charging and shut down. When power is reapplied to the ADP
pin or the UVLO condition recovers, the system charge
control will automatically resume charging in the appropriate mode for the condition of the battery. If the input
voltage of the step-down converter drops below UVLO,
the internal circuit will shut down.
Protection Circuitry
Over-Voltage Protection
An over-voltage protection event is defined as a condition
where the voltage on the BAT pin exceeds the over-voltage protection threshold (VOVP). If this over-voltage condition occurs, the charger control circuitry will shut down
the device. The charger will resume normal charging
operation after the over-voltage condition is removed.
Current Limit, Over-Temperature Protection
For overload conditions, the peak input current is limited
at the step-down converter. As load impedance decreases and the output voltage falls closer to zero, more
power is dissipated internally, which causes the internal
die temperature to rise. In this case, the thermal protection circuit completely disables switching, which protects
the device from damage.
The battery charger has a thermal protection circuit which
will shut down charging functions when the internal die
temperature exceeds the preset thermal limit threshold.
Once the internal die temperature falls below the thermal
limit, normal charging operation will resume.
Control Loop
The AAT2554 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
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
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DATA SHEET
AAT2554
Total Power Solution for Portable Applications
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
voltage reaches the voltage regulation point, VBAT. When
Preconditioning
Trickle Charge
Phase
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.
18
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DATA SHEET
AAT2554
Total Power Solution for Portable Applications
Battery Charging System Operation Flow Chart
Enable
No
Power On Reset
Yes
Power Input
Voltage
VADP > VUVLO
Yes
Shutdown
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
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19
DATA SHEET
AAT2554
Total Power Solution for Portable Applications
Application Information
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.
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.
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
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.
Table 1: RSET Values.
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.
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
20
ICH (mA)
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 AAT2554 into a lowpower, non-switching state. The total input current during shutdown is less than 1μA.
1000
100
10
1
1
10
100
1000
RSET (kΩ
Ω)
Figure 2: Constant Charging Current
vs. Set Resistor Values.
Charge Status Output
The AAT2554 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
Charging completed
OFF
ON or USB port
OFF
Table 2: LED Status Indicator.
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DATA SHEET
AAT2554
Total Power Solution for Portable Applications
Figure 3 shows the relationship of maximum power dissipation and ambient temperature of the AAT2554.
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))
R 1=
ILED
20
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 AAT2554 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)
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
AAT2554
Total Power Solution 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
+ (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 TDFN34-16 package which is 50°C/W.
TJ(MAX) = PTOTAL · ΘJA + TAMB
22
Linear Regulator Input Capacitor (C7)
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 (C3)
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 (C1)
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
⎠
VO ⎛
V ⎞
1
· 1 - O = for VIN = 2 · VO
VIN ⎝
VIN ⎠
4
CIN(MIN) =
1
⎛ VPP
⎞
- ESR · 4 · FS
⎝ IO
⎠
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DATA SHEET
AAT2554
Total Power Solution for Portable Applications
Always examine the ceramic capacitor DC voltage coefficient characteristics when selecting the proper value.
For example, the capacitance of a 10μF, 6.3V, X5R
ceramic capacitor with 5.0V DC applied is actually about
6μF.
The maximum input capacitor RMS current is:
IRMS = IO ·
VO ⎛
V ⎞
· 1- O
VIN ⎝
VIN ⎠
The input capacitor RMS ripple current varies with the
input and output voltage and will always be less than or
equal to half of the total DC load current.
VO ⎛
V ⎞
· 1- O =
VIN ⎝
VIN ⎠
D · (1 - D) =
0.52 =
1
2
for VIN = 2 · VO
IRMS(MAX) =
VO
IO
2
VO
The term VIN · 1 - 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 (C1) 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.
Linear Regulator Output Capacitor (C6)
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 (C5)
The AAT2554 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 AAT2554 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.
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DATA SHEET
AAT2554
Total Power Solution for Portable Applications
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.
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 AAT2554 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=
24
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
For most designs, the step-down converter operates with
inductor values from 1μH to 4.7μH. Table 3 displays
inductor values for the AAT2554 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.
Output Voltage (V)
L1 (μH)
1.0
1.2
1.5
1.8
2.5
3.0
3.3
1.5
2.2
2.7
3.0/3.3
3.9/4.2
4.7
5.6
Table 3: Step-Down Converter Inductor Values.
Adjustable Output Resistor Selection
Resistors R2 and R3 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 R3 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 ⎞
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.
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DATA SHEET
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Total Power Solution for Portable Applications
VINB
VINB
C1
4.7μF
U1
ADP
ADP
11
R4
1K
C3
4.7μF
9
D1
VINA
4
ENA
R5
100K
VINB
C7
2.2μF
16
13
3
JP2
6
R6
100K
JP3
ADP
R7
100K
JP1
3
2
3
2
7
1
ENB
ENA
ENB
BAT
ADP
OUTA
STAT
LX
VINA
FB
ENA
GND
ENB
GND
EN_BAT GND
ISET
GND
8
5
15
1
2
VOUTA
L1
VOUTA
VOUTB
VOUTB
1
R2
118K
14
FB
12
10
R3
59K
2
AAT2554
C8
100pF
C8 optional for
enhanced stepdown converter
transient
response
C4
4.7μF
C6
2.2μF
C5
2.2μF
R1
8.06K
1
3
VBAT
VINB
EN_BAT
2
1
GND
EN_BAT
Figure 5: AAT2554 Evaluation Board Schematic.
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
example (see Figures 6 and 7). The following guidelines
should be used to help ensure a proper layout.
1.
2.
3.
Table 4: Adjustable Resistor Values For
Step-Down Converter.
Printed Circuit Board
Layout Considerations
For the best results, it is recommended to physically
place the battery pack as close as possible to the
AAT2554 BAT pin. To minimize voltage drops on the PCB,
keep the high current carrying traces adequately wide.
Refer to the AAT2554 evaluation board for a good layout
4.
5.
The input capacitors (C1, C3, C7) should connect as
closely as possible to ADP (Pin 11), VINA (Pin 4),
and VINB (Pin 16).
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 (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 GND
(Pins 2, 10, 12, and 14) 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
AAT2554
Total Power Solution for Portable Applications
Figure 6: AAT2554 Evaluation Board
Top Side Layout.
Figure 7: AAT2554 Evaluation Board
Bottom Side Layout.
Component
Part Number
Description
Manufacturer
U1
C1, C3, C4
C5, C6, C7
C8
L1
R4
R1
R2
R3
R5, R6, R7
JP1, JP2, JP3
D1
AAT2554IRN-T1
GRM188R60J475KE19
GRM188R61A225KE34
GRM1886R1H101JZ01J
CDRH2D09-3R0
Chip Resistor
Chip Resistor
Chip Resistor
Chip Resistor
Chip Resistor
PRPN401PAEN
CMD15-21SRC/TR8
Total Power Solution for Portable Applications
Ceramic 4.7μF 6.3V X5R 0603
Ceramic 2.2μF 10V X5R 0603
Ceramic 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
100k, 5%, 1/8W; 0402
Connecting Header, 2mm zip
Red LED; 1206
Skyworks
Murata
Murata
Murata
Sumida
Vishay
Vishay
Vishay
Vishay
Vishay
Sullins Electronics
Chicago Miniature Lamp
Table 5: AAT2554 Evaluation Board Component Listing.
26
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DATA SHEET
AAT2554
Total Power Solution 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.
⎛
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)
0.1V · 1.5MHz
VDROOP · FS
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
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DATA SHEET
AAT2554
Total Power Solution for Portable Applications
AAT2554 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
28
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DATA SHEET
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Total Power Solution for Portable Applications
VOUT (V)
R2 (k)
R2 (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
0
19.6
29.4
39.2
49.9
59.0
68.1
78.7
88.7
118
124
137
187
267
0
75
113
150
187
221
261
301
332
442
464
523
715
1000
1.5
1.5
1.5
1.5
1.5
1.5
1.5
2.2
2.7
3.0/3.3
3.0/3.3
3.0/3.3
3.9/4.2
5.6
Table 6: Step-Down Converter Component Values.
Manufacturer
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.
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.
1. For reduced quiescent current, R3 = 221k.
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DATA SHEET
AAT2554
Total Power Solution for Portable Applications
Ordering Information
Package
Marking1
Part Number (Tape and Reel)2
TDFN34-16
TDFN34-16
TDFN34-16
RZXYY
SAXYY
TOXYY
AAT2554IRN-CAP-T1
AAT2554IRN-CAT-T1
AAT2554IRN-CAW-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 (0.6V)
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
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
AAT2554
Total Power Solution for Portable Applications
Package Information1
TDFN34-16
1.600 ± 0.050
0.35 REF
R0.15 (REF)
Pin 1 ID
0.450 ± 0.050
0.230 ± 0.050
4.000 ± 0.050
Index Area
2.350 ± 0.050
0.700 ± 0.050
3.000 ± 0.050
0.25 REF
0.430 ± 0.050
1.600 ± 0.050
0.750 ± 0.050
Top View
0
+ 0.100
-0.000
Bottom View
0.230 ± 0.050
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 • [email protected] • www.skyworksinc.com
202176B • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • March 19, 2013
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