AAT2603
Total Power Solution for Portable Applications
PRODUCT DATASHEET
2603.2008.06.1.0 1
www.analogictech.com
General Description
The AAT2603 is a highly integrated power management
solution for handheld mobile systems. It provides six
regulated voltages from a single-cell Lithium-ion/poly-
mer battery or a 5V supply.
The six outputs are produced by six regulators; two
switching step-down regulators and four low-dropout
(LDO) regulators. Each voltage regulator has its own
independent enable pin.
The high efficiency step-down regulators are fully inte-
grated and switch at a high 1.5 MHz fixed frequency.
They automatically transition to variable frequency
operation at light loads for improved efficiency. DC-DC1
(Buck1) is designed for high output current and low
dropout voltage (200mV at 1.2A). DC-DC2 (Buck2) is a
600mA regulator with a two step dynamic output voltage
capability. One option allows the output voltage of
DC-DC2 (Buck2) to be set to either 1.0V or 1.3V with the
SELB2 logic pin.
LDO regulators LDO1 and LDO2 can supply up to 400mA
of load current with output voltages adjustable down to
1.5V. LDO regulators LDO3 and LDO4 can supply up to
200mA of current and provide good noise and power sup-
ply rejection. LDO3 and LDO4 have output voltages exter-
nally adjustable down to 1.2V.
The AAT2603 is available in a Pb-free thermally enhanced
28-pin TQFN44 package and is rated for operation over
the -40°C to +85°C temperature range.
Features
• V
IN Range: 2.7V to 5.5V
• Two Step-Down Regulators
DC-DC1(Buck1): 1.2A, Low Dropout Voltage
• Externally Adjustable: VFBB1 = 0.6V
V
OUT Range: 0.6V to VINB1
• Fixed: VOUT = 3.3V
Factory Programmable to any Two Voltage
Levels from 0.6V to 4.0V
• DC-DC2(Buck2): 0.6A, Low Dropout Voltage
• Externally Adjustable: VFBB2 = 0.6V
V
OUT Range: 0.6V to VINB2
•
Fixed: VOUT = 1.0V[SELB2=’0’]/1.3V[SELB2=’1’]
Factory Programmable to any Two Voltage
Levels from 0.6V to 4.0V
Fixed 1.5MHz Switching Frequency
Internally Compensated Current Mode Control
High Efficiency over the Entire Load Range
Four LDO Regulators
• LDO1: 400mA LDO
• LDO2: 400mA LDO
• LDO3: 200mA, Low Noise LDO
• LDO4: 200mA, Low Noise LDO
• Fast Turn-On and Turn-Off time
• Short Circuit and Over-Current Protection
• Over-Temperature Protection
• Temperature Range: -40°C to +85°C
• TQFN44-28 Package
Applications
• Handheld GPS
• Handheld Instruments
• PDAs and Handheld Computers
• Portable Media Players
• Smart Phones
AAT2603
Total Power Solution for Portable Applications
PRODUCT DATASHEET
2 2603.2008.06.1.0
www.analogictech.com
Typical Application Circuit
AAT2603
INB1
FBB 1
LX2
FBB 2
OUTL1
OUTL2
OUTL3
OUTL4
FBL 1
FBL 2
FBL3
FBL4
INB2
LX1
ENB2
3.3V: 1.2A
1.0V & 1.3V: 600m
A
1.2V (Minimum): 200mA
1.2V (Minimum): 200mA
1.5V (Minimum): 400mA
1.5V (Minimum): 400mA
PGND2PGND1AGND
BYP
ENL 1
ENL 2
ENL 3
ENL 4
SELB 2
ENB1
COUTL3
4.7μF
COUTL4
4.7μF
COUTL1
4.7μF
COUTL2
4.7μF
100kΩ
100kΩ
100kΩ
100kΩ
CBYP
10nF
CINL12
2.2μF
COUTB1
22μF
L1
3.3μH
L2
1.2μH
COUTB2
10μF
INL 34
INL 12
AIN
CINL34
2.2μF
2.7V to 5.5V
CAIN
2.2μF
CINB2
4.7μF
CINB1
4.7μF
AAT2603
Total Power Solution for Portable Applications
PRODUCT DATASHEET
2603.2008.06.1.0 3
www.analogictech.com
AAT2603
Total Power Solution for Portable Applications
PRODUCT DATASHEET
2603.2008.06.1.0 3
www.analogictech.com
Pin Descriptions
Pin # Symbol Function
1 LX2 DC-DC2 (Buck2) switching node. Connect the output inductor to LX2. Connected internally to the
drains o f both high-side and low-side switches.
2 ENB2 DC-DC2 (Buck2) enable input. Active high.
3 FBB2 DC-DC2 (Buck2) feedback input. For externally adjustable versions, connect a resistor divider
from Buck2 output to FBB2 to AGND to set the Buck2 output voltage.
4 ENL3 LDO3 enable input. Active high.
5 AGND Analog ground. Connect AGND to PGND1 and PGND2 as close as possible to the device.
6 FBL3 LDO3 feedback input. Connect a resistor divider from OUTL3 to FBL3 to AGND to set the LDO3
output voltage.
7 OUTL3 LDO3 output. Should be closely decoupled to AGND with a 4.7F or greater capacitor.
8 INL34 LDO3 and LDO4 input. Should be closely decoupled to AGND with a 2.2F or greater capacitor.
9 OUTL4 LDO4 output. Should be closely decoupled to AGND with a 4.7F or greater capacitor.
10 FBL4 LDO4 feedback input. Connect a resistor divider from OUTL4 to FBL4 to AGND to set the LDO4
output voltage.
11 ENL4 LDO4 enable input. Active high.
12 BYP Reference Bypass. Bypass BYP to AGND with a 0.01F or greater capacitor to reduce the LDO1
output noise.
13 ENL1 LDO1 enable input. Active high.
14 FBL1 LDO1 feedback input. Connect a resistor divider from OUTL1 to FBL1 to AGND to set the LDO1
output voltage.
15 OUTL1 LDO1 output. Should be closely decoupled to AGND with a 4.7F or greater capacitor.
16 INL12 LDO1 and LDO2 input. Should be closely decoupled to AGND with a 2.2F or greater capacitor.
17 OUTL2 LDO2 output. Should be closely decoupled to AGND with a 4.7F or greater capacitor.
18 FBL2 LDO2 feedback input. Connect a resistor divider from OUTL2 to FBL2 to AGND to set the LDO2
output voltage.
19 ENL2 LDO2 enable input. Active high.
20 AIN Analog voltage input. AIN is the bias supply for the device. Should be closely decoupled to AGND
with a 2.2F or greater capacitor.
21 FBB1 DC-DC1 (Buck1) feedback input. For externally adjustable versions, connect a resistor divider
from Buck1 output to FBB1 to AGND to set the Buck1 output voltage.
22 ENB1 DC-DC1 (Buck1) enable input. Active high.
23 SELB2 Dynamically adjusts the output voltage of DC-DC2 (Buck2) (Logic High=1.3V, Logic Low=1.0V)
24 LX1 DC-DC1 (Buck1) switching node. Connect the output inductor to LX1. Connected internally to the
drains of both high-side and low-side switches.
25 PGND1 DC-DC1 (Buck1) power ground. Connected internally to the source of the Buck1 N-channel syn-
chronous rectifi er. Connect PGND1 to PGND2 and AGND as close as possible to the device.
26 INB1 DC-DC1 (Buck1) power input. Connected internally to the source of the Buck1 P-channel switch.
Should be closely decoupled to PGND1 with a 4.7F or greater capacitor.
27 INB2 DC-DC2 (Buck2) power input. Connected internally to the source of the Buck2 P-channel switch.
Should be closely decoupled to PGND2 with a 4.7F or greater capacitor.
28 PGND2 DC-DC2 (Buck2) power ground. Connected internally to the source of the Buck2 N-channel syn-
chronous rectifi er. Connect PGND2 to PGND1 and AGND as close as possible to the device.
EP Exposed paddle (bottom). Connect to ground as close as possible to the device.
AAT2603
Total Power Solution for Portable Applications
PRODUCT DATASHEET
4 2603.2008.06.1.0
www.analogictech.com
AAT2603
Total Power Solution for Portable Applications
PRODUCT DATASHEET
4 2603.2008.06.1.0
www.analogictech.com
Pin Configuration
TQFN44-28
(Top View)
1
2
3
4
5
6
7
89
EP
10
28 27 26 25 24 23 22
11 12 13 14
21
20
19
18
17
16
15
LX2
ENB2
FBB2
ENL3
AGND
FBL3
OUTL3
INL34
OUTL4
FBL4
ENL4
BYP
ENL1
FBL1
FBL2
ENL2
OUTL2
INL12
OUTL1
AIN
FBB1
SELB2
ENB1
LX1
PGND1
INB1
INB2
PGND2
Part Number Descriptions
Part Number
Output Voltage1
DC-DC1 (Buck1)
DC-DC2 (Buck2)
(SELB2 = Low)
DC-DC2 (Buck2)
(SELB2 = High) LDOs 1-4
AAT2603INJ-1-T1 Ext. Adj. (VFBB1 = 600mV) Ext. Adj. (VFBB2 = 600mV) Ext. Adj. (VFBB2 = 775mV) Ext. Adj. (VFBLX = 1.2V)
AAT2603INJ-2-T1 3.3V 1.0V 1.3V Ext. Adj. (VFBLX = 1.2V)
AAT2603INJ-3-T1 Ext. Adj. (VFBB1 = 600mV) 1.0V 1.3V Ext. Adj. (VFBLX = 1.2V)
Absolute Maximum Ratings1
TA = 25°C unless otherwise noted.
Symbol Description Value Units
INBX, INLXX, AIN to AGND -0.3 to 6.0 V
ENBX, ENLX, FBBX, FBLX, BYP to AGND -0.3 to VAIN+0.3 V
LX1 to PGND1 -0.3 to VINB1+0.3 V
LX2 to PGND2 -0.3 to VINB2+0.3 V
PGNDX to AGND, PGND1 to PGND2 -0.3 to 0.3 V
Operating Temperature Range -40 to 150 °C
Storage Temperature Range -65 to 150 °C
Maximum Soldering Temperature (at leads, 10 sec) 300 °C
Recommended Operating Conditions
Symbol Description Value Units
JA Thermal Resistance 50 °C/W
PDMaximum Power Dissipation 2W
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.
AAT2603
Total Power Solution for Portable Applications
PRODUCT DATASHEET
2603.2008.06.1.0 5
www.analogictech.com
AAT2603
Total Power Solution for Portable Applications
PRODUCT DATASHEET
2603.2008.06.1.0 5
www.analogictech.com
Electrical Characteristics1
VAIN = VINB1 = VINB2 = VINL12 = VINL34 = 3.6V, CBYP = 10nF, TA = -40°C to 85°C, unless noted otherwise. Typical values are
at TA = 25°C.
Symbol Description Conditions Min Typ Max Units
Power Supply
VIN Input Voltage Range 2.7 5.5 V
IQQuiescent Current
VENB1 = VENL3 = 3.6V, No Load , VFBB1 = VFBL3 = 3.6V
100 200 A
ISHDN Input Shutdown Current VENx = AGND 1.0 A
UVLO Under-Voltage Lockout
VIN rising 2.6 V
VIN falling 1.8 V
Hysteresis 250 mV
FOSC Oscillator Frequency 1.5 MHz
tS,BYP Bypass Filter Startup Time VENB1 = 3.6V 200 s
DC-DC1 (Buck1): 1.2A Step-Down Converter
VOUT_RANGE Output Voltage Range 0.6 VINB1 V
VOUT_ACC Output Voltage Accuracy TA = 25°C, 20mA Load -1.5 +1.5 %
TA = -40°C to 85°C, 20mA Load -2.5 +2.5 %
VOUT_TOL Output Voltage Tolerance 0A to 1.2A Load; VIN = 2.7V to 5.5V -3.0 +3.0 %
VFBB1_ACC Feedback Voltage Accuracy TA = 25°C, 20mA Load 0.591 0.6 0.609 V
TA = -40°C to 85°C, 20mA Load 0.585 0.6 0.615 V
VOUT/IOUT Load Regulation 0A to 1.2A Load 0.4 %
VOUT/VIN Line Regulation VIN = 2.7V to 5.5V 0.2 %/V
ISHDN Shutdown Current VENB1 = GND 1.0 A
ILX_LEAK LX Leakage Current VINB1 = 5.5V, VLX1 = 0V to VINB1 1.0 A
ILIM P-Channel Current Limit 1.7 A
RDS(ON)H High Side Switch On-Resistance 145 m
RDS(ON)L Low Side Switch On-Resistance 200 m
tSStart-Up Time Enable to Output Regulation 200 s
DC-DC2 (Buck2): 600mA Step-Down Converter
VOUT_RANGE Output Voltage Range 0.6 VINB2 V
VOUT_ACC Output Voltage Accuracy TA = 25°C, 20mA Load -1.5 +1.5 %
TA = - 40°C to 85°C, 20mA Load -2.5 +2.5 %
VOUT_TOL Output Voltage Tolerance 0mA to 600mA Load; VIN = 2.7V to 5.5V -3.0 +3.0 %
VFBB2_ACC
Feedback Voltage Accuracy
SELB2 = '0
TA = 25°C, 20mA Load 0.591 0.6 0.609 V
TA = -40°C to 85°C, 20mA Load 0.585 0.6 0.615
Feedback Voltage Accuracy
SELB2 = '1'
TA = 25°C, 20mA Load 0.763 0.775 0.787 V
TA = -40°C to 85°C, 20mA Load 0.756 0.775 0.794
VOUT/IOUT Load Regulation 0mA to 600mA Load 0.2 %
VOUT/VIN Line Regulation VIN = 2.7V to 5.5V 0.2 %/V
ISHDN Shutdown Current VENB2 = GND 1.0 A
ILX_LEAK LX Leakage Current VINB2 = 5.5V, VLX2 = 0 to VINB2 1.0 A
ILIM P-Channel Current Limit 1.3 A
RDS(ON)H High Side Switch On-Resistance 230 m
RDS(ON)L Low Side Switch On-Resistance 180 m
tSStart-Up Time Enable to Output Regulation 200 s
1.
The AAT2603 is guaranteed to meet performance specification from -40°C to +85°C and is assured by design, characterization and correlation with statistical process controls.
AAT2603
Total Power Solution for Portable Applications
PRODUCT DATASHEET
6 2603.2008.06.1.0
www.analogictech.com
AAT2603
Total Power Solution for Portable Applications
PRODUCT DATASHEET
6 2603.2008.06.1.0
www.analogictech.com
Electrical Characteristics1
VAIN = VINB1 = VINB2 = VINL12 = VINL34 = 3.6V, CBYP = 10nF, TA = -40°C to 85°C, unless noted otherwise. Typical values are
at TA = 25°C.
Symbol Description Conditions Min Typ Max Units
400mA LDO Regulators (LDO1, LDO2)
VOUT_RANGE Output Voltage Range 1.5 VINL12 V
VFB_ACC Feedback Voltage Accuracy TA = 25°C, 1mA Load 1.2 1.218 V
TA = -40°C to 85°C, 1mA Load 1.2 1.23 V
VFB_TOL Feedback Voltage Tolerance 0mA to 400mA Load, VIN = 2.7V to 5.5V 1.2 1.236 V
VOUT/IOUT Load Regulation 1mA to 400mA Load 0.3 %
VOUT/VIN Line Regulation VIN = 3.3V to 5.5V, 100mA Load 0.08 %/V
IOUT(MAX) Maximum Output Current 400 mA
ILIM Output Current Limit 1000 mA
VDO Dropout Voltage 400mA Load 300 500 mV
PSRR Power Supply Rejection Ratio f < 10KHz, COUTL1,2 = 4.7F, 10mA Load 50 dB
tSStart-Up Time VBYP already enabled; COUT = 4.7F 200 s
200mA LDO Regulators (LDO3, LDO4)
VOUT_RANGE Output Voltage Range 1.2 VINL34 V
VFB_ACC Feedback Voltage Accuracy TA = 25°C, 1mA Load 1.182 1.218 V
TA = -40°C to +85°C, 1mA Load 1.17 1.23 V
VFB_TOL Feedback Voltage Tolerance 0mA to 200mA Load, VIN = 2.7V to 5.5V 1.164 1.236 V
VOUT/IOUT Load Regulation 0mA to 200mA Load 0.2 %
VOUT/VIN Line Regulation VIN = 3.3V to 5.5V, 100mA Load 0.02 %/V
IOUT(MAX) Maximum Output Current 200 mA
ILIM Output Current Limit 1500 mA
VDO Dropout Voltage 200mA Load 200 350 mV
PSRR Power Supply Rejection Ratio f < 10KHz, COUTL3,4 = 4.7F, 10mA Load 50 dB
eNRMS Output Noise Power BW: 100~100KHz 45 Vrms
tSStart-Up Time VBYP already enabled; COUT = 4.7F 200 s
Logic Inputs/Outputs
VEN(H) Input Logic High Voltage 1.4 V
VEN(L) Input Logic Low Voltage 0.4 V
IEN Logic Input Current VEN = 1.4V21.5 A
Thermal
TSD Over-Temperature Shutdown Threshold 140 °C
TSD(HYS) Over-Temperature Shutdown Hysteresis 15 °C
1.
The AAT2603 is guaranteed to meet performance specification from -40°C to +85°C and is assured by design, characterization and correlation with statistical process controls.
2. The enable pins have internal 1.6M pull-down resistors.
AAT2603
Total Power Solution for Portable Applications
PRODUCT DATASHEET
2603.2008.06.1.0 7
www.analogictech.com
AAT2603
Total Power Solution for Portable Applications
PRODUCT DATASHEET
2603.2008.06.1.0 7
www.analogictech.com
Typical Characteristics—DC-DC1 (Buck1)
Efficiency vs. Output Current
(VOUTB1 = 3.3V; L = 3.3µH)
Output Current (mA)
Efficiency (%)
0
10
20
30
40
50
60
70
80
90
100
1000010001001010.1
VIN = 5V
VIN = 4.2V
VIN = 3.6V
Load Regulation
(VOUTB1 = 3.3V; L = 3.3µH)
Output Current (mA)
Output Voltage Error (%)
-0.4
-0.2
0
0.2
0.4
10000
10001001010.1
VIN = 5V
VIN = 4.2V
VIN = 3.6V
Line Regulation
(VOUTB1 = 3.3V; L = 3.3µH)
Input Voltage (V)
Output Voltage Error (%)
-0.4
-0.2
0
0.2
0.4
5.2
4.84.4
4
3.6
IOUT = 1.2A
IOUT = 600mA
IOUT = 300mA
IOUT = 100mA
IOUT = 10mA
IOUT = 1mA
IOUT = 0.1mA
Output Voltage Error vs. Temperature
(VOUTB1 = 3.3V; VIN = 4.2V)
Temperature (°C)
Output Voltage Error (%)
-0.4
-0.2
0
0.2
0.4
856035
10
-15-40
IOUT = 1.2A
IOUT = 0.1mA
P-Channel RDS(ON) vs. Input Voltage
(VOUTB1 = 3.3V)
Input Voltage (V)
P-Channel RDS(ON) (mΩ)
0
50
100
150
200
250
2.7 3.1 3.5 3.9 4.3 4.7 5.1 5.5
T = 120°C
T = 100°C
T = 85°C
T = 25°C
Load Transient
(VOUTB1 = 3.3V; VIN = 4.2V; IOUTB1 = 100mA to 1200mA; CFF = 0pF)
Time (100µs/div)
Output Voltage
(AC Coupled) (top)
Output Current
(bottom)
-0.4
-0.2
0
0.2
0.4
0
0.5
1
1.5
AAT2603
Total Power Solution for Portable Applications
PRODUCT DATASHEET
8 2603.2008.06.1.0
www.analogictech.com
AAT2603
Total Power Solution for Portable Applications
PRODUCT DATASHEET
8 2603.2008.06.1.0
www.analogictech.com
Typical Characteristics—DC-DC1 (Buck1)
Load Transient
(VOUTB1 = 3.3V; VIN = 4.2V; IOUTB1 = 100mA to 1200mA; CFF = 100pF)
Time (100µs/div)
Output Voltage
(AC Coupled) (top)
Output Current
(bottom)
-0.1
-0.2
0
0.1
0
0.5
1
1.5
Load Transient
(VOUTB1 = 3.3V; VIN = 4.2V; IOUTB1 = 600mA to 1200mA; CFF = 0pF)
Time (50µs/div)
Output Voltage
(AC Coupled) (top)
Output Current
(bottom)
-0.2
-0.1
0
0.1
0.2
0
0.5
1
1.5
Load Transient
(VOUTB1 = 3.3V; VIN = 4.2V; IOUTB1 = 600mA to 1200mA; CFF = 100pF)
Time (50µs/div)
Output Voltage
(AC Coupled) (top)
Output Current
(bottom)
-0.1
-0.2
0
0.1
0
0.5
1
1.5
Line Transient
(VOUTB1 = 3.3V; VIN = 4.2V to 5V; IOUTB1 = 700mA)
Time (100µs/div)
Input Voltage (top)
Output Voltage
(AC Coupled) (bottom)
4
5
-0.2
-0.1
0
0.1
Soft-Start
(VOUTB1 = 3.3V; VIN = 4.2V; IOUTB1 = 1.2A)
Time (100µs/div)
Enable Voltage (top)
Output Voltage
(bottom)
0
2
4
6
0
1
2
3
4
AAT2603
Total Power Solution for Portable Applications
PRODUCT DATASHEET
2603.2008.06.1.0 9
www.analogictech.com
AAT2603
Total Power Solution for Portable Applications
PRODUCT DATASHEET
2603.2008.06.1.0 9
www.analogictech.com
Typical Characteristics—DC-DC2 (Buck2)
Efficiency vs. Output Current
(VOUTB2 = 1.3V; L = 1.5µH)
Output Current (mA)
Efficiency (%)
0
10
20
30
40
50
60
70
80
90
100
100 1000
101
0.1
VIN = 5V
VIN = 4.2V
VIN = 3.6V
VIN = 2.7V
Efficiency vs. Output Current
(VOUTB2 = 1V; L = 1.2µH)
Output Current (mA)
Efficiency (%)
0
10
20
30
40
50
60
70
80
90
100
10001001010.1
VIN = 5V
VIN = 4.2V
VIN = 3.6V
VIN = 2.7V
Load Regulation
(VOUTB2 = 1.3V; L = 1.5µH)
Output Current (mA)
Output Voltage Error (%)
-0.4
-0.2
0
0.2
0.4
1000
100
10
10.1
VIN = 5V
VIN = 4.2V
VIN = 3.6V
VIN = 2.7V
Load Regulation
(VOUTB2 = 1V; L = 1.2µH)
Output Current (mA)
Output Voltage Error (%)
-0.4
-0.2
0
0.2
0.4
10000
10001001010.1
VIN = 5V
VIN = 4.2V
VIN = 3.6V
VIN = 2.7V
Line Regulation
(VOUTB2 = 1.3V; L = 1.5µH)
Input Voltage (V)
Output Voltage Error (%)
-0.6
-0.4
-0.2
0
0.2
0.4
0.6
2.7 3.1 3.5 3.9 4.3 4.7 5.1 5.5
IOUT = 600mA
IOUT = 300mA
IOUT = 100mA
IOUT = 10mA
IOUT = 1mA
IOUT = 0.1mA
Line Regulation
(VOUTB2 = 1V; L = 1.2µH)
Input Voltage (V)
Output Voltage Error (%)
-0.6
-0.4
-0.2
0
0.2
0.4
0.6
2.7 3.1 3.5 3.9 4.3 4.7 5.1 5.5
IOUT = 600mA
IOUT = 300mA
IOUT = 100mA
IOUT = 10mA
IOUT = 1mA
IOUT = 0.1mA
AAT2603
Total Power Solution for Portable Applications
PRODUCT DATASHEET
10 2603.2008.06.1.0
www.analogictech.com
AAT2603
Total Power Solution for Portable Applications
PRODUCT DATASHEET
10 2603.2008.06.1.0
www.analogictech.com
Typical Characteristics—DC-DC2 (Buck2)
Output Voltage Error vs. Temperature
(VOUTB2 = 1.3V; VIN = 3.6V)
Temperature (°C)
Output Voltage Error (%)
-0.6
-0.4
-0.2
0
0.2
0.4
0.6
85603510-15-40
IOUT = 600mA
IOUT = 0.1mA
Switching Frequency vs. Input Voltage
(VOUTB2 = 1.3V; IOUTB2 = 600mA)
Input Voltage (V)
Switching Frequency (MHz)
1.46
1.465
1.47
1.475
1.48
1.485
1.49
1.495
1.5
1.505
2.7 3.1 3.5 3.9 4.3 4.7 5.1 5.5
P-Channel RDS(ON) vs. Input Voltage
(VOUTB2 = 1.3V)
Input Voltage (V)
P-Channel RDS(ON) (mΩ)
0
50
100
150
200
250
300
350
400
2.7 3.1 3.5 3.9 4.3 4.7 5.1 5.5
T = 120°C
T = 100°C
T = 85°C
T = 25°C
Load Transient
(VOUTB2 = 1.3V; VIN = 3.6V; IOUTB2 = 100mA to 600mA; CFF = 0pF)
Time (50µs/div)
Output Voltage
(AC Coupled) (top)
Output Current
(bottom)
-0.1
-0.05
0
0.05
0.1
0
0.5
1
Load Transient
(VOUTB2 = 1.3V; VIN = 3.6V; IOUTB2 = 100mA to 600mA; CFF = 100pF)
Time (50µs/div)
Output Voltage
(AC Coupled) (top)
Output Current
(bottom)
-0.1
-0.05
0
0.05
0.1
0
0.5
1
Load Transient
(VOUTB2 = 1.3V; VIN = 3.6V; IOUTB2 = 300mA to 600mA; CFF = 0pF)
Time (20µs/div)
Output Voltage
(AC Coupled) (top)
Output Current
(bottom)
-0.05
0
0.05
0
0.5
1
AAT2603
Total Power Solution for Portable Applications
PRODUCT DATASHEET
2603.2008.06.1.0 11
www.analogictech.com
AAT2603
Total Power Solution for Portable Applications
PRODUCT DATASHEET
2603.2008.06.1.0 11
www.analogictech.com
Typical Characteristics—DC-DC2 (Buck2)
Load Transient
(VOUTB2 = 1.3V; VIN = 3.6V; IOUTB2 = 300mA to 600mA; CFF = 100pF)
Time (20µs/div)
Output Voltage
(AC Coupled) (top)
Output Current
(bottom)
-0.05
0
0.05
0
0.5
1
Line Transient
(VOUTB2 = 1.3V; VIN = 3.6 to 4.2V; IOUTB2 = 300mA)
Time (50µs/div)
Input Voltage (top)
Output Voltage
(AC Coupled) (bottom)
-2
-1
0
1
2
3
4
5
6
-0.1
-0.05
0
0.05
0.1
0.15
0.2
0.25
0.3
Soft-Start
(VOUTB2 = 1.3V; VIN = 3.6V; IOUTB2 = 600mA)
Time (100µs/div)
Enable Voltage (top)
Output Voltage
(bottom)
0
2
4
0
0.5
1
1.5
AAT2603
Total Power Solution for Portable Applications
PRODUCT DATASHEET
12 2603.2008.06.1.0
www.analogictech.com
AAT2603
Total Power Solution for Portable Applications
PRODUCT DATASHEET
12 2603.2008.06.1.0
www.analogictech.com
Typical Characteristics—LDO1/LDO2
Load Regulation
(VOUTL1&2 = 3V; VIN = 3.6V)
Output Current (mA)
Output Voltage Error (%)
-0.4
-0.2
0
0.2
0.4
10001001010.1
Load Regulation
(VOUTL1&2 = 1.5V; VIN = 3.6V)
Output Current (mA)
Output Voltage Error (%)
-0.4
-0.2
0
0.2
0.4
100010010
10.1
Line Regulation
(VOUTL1&2 = 1.5)
Input Voltage (V)
Output Voltage Error (%)
-0.4
-0.2
0
0.2
0.4
2.7 3.1 3.5 3.9 4.3 4.7 5.1 5.5
IOUT = 400mA
IOUT = 100mA
IOUT = 10mA
IOUT = 1mA
IOUT = 0.1mA
Output Voltage Error vs. Temperature
(VOUTL1&2 = 2.8V; VIN = 3.6V)
Temperature (°C)
Output Voltage Error (%)
-0.4
-0.2
0
0.2
0.4
856035
10
-15-40
IOUT = 400mA
IOUT = 0.1mA
Load Transient
(VOUTL1&2 = 2.8V; VIN = 3.6V; IOUTL1&2 = 1mA to 50mA)
Time (100µs/div)
Output Voltage
(AC Coupled) (top)
Output Current
(bottom)
-0.04
-0.02
0
0.02
0.04
-0.05
0
0.05
Load Transient
(VOUTL1&2 = 2.8V; VIN = 3.6V; IOUTL1&2 = 1mA to 200mA)
Time (100µs/div)
Output Voltage
(AC Coupled) (top)
Output Current
(bottom)
-0.1
-0.05
0
0.05
0.1
-0.2
0
0.2
0.4
AAT2603
Total Power Solution for Portable Applications
PRODUCT DATASHEET
2603.2008.06.1.0 13
www.analogictech.com
AAT2603
Total Power Solution for Portable Applications
PRODUCT DATASHEET
2603.2008.06.1.0 13
www.analogictech.com
Typical Characteristics—LDO1/LDO2
Load Transient
(VOUTL1&2 = 2.8V; VIN = 3.6V; IOUTL1&2 = 1mA to 400mA)
Time (200µs/div)
Output Voltage
(AC Coupled) (top)
Output Current
(bottom)
-0.2
-0.1
0
0.1
0.2
0
0.5
Line Transient
(VOUTL1&2 = 2.8V; VIN = 3.6 to 4.2V; IOUTL1&2 = 400mA)
Time (20µs/div)
Input Voltage (top)
Output Voltage
(bottom)
3
4
5
-0.2
-0.1
0
0.1
0.2
Soft-Start
(VOUTL1&2 = 2.8V; VIN = 3.6V; IOUTL1&2 = 400mA)
Time (500µs/div)
Enable Voltage (top)
Output Voltage
(bottom)
0
2
4
0
1
2
3
AAT2603
Total Power Solution for Portable Applications
PRODUCT DATASHEET
14 2603.2008.06.1.0
www.analogictech.com
AAT2603
Total Power Solution for Portable Applications
PRODUCT DATASHEET
14 2603.2008.06.1.0
www.analogictech.com
Typical Characteristics—LDO3/LDO4
Load Regulation
(VOUTL3&4 = 3V; VIN = 3.6V)
Output Current (mA)
Output Voltage Error (%)
-0.4
-0.2
0
0.2
0.4
1000
100
10
10
Load Regulation
(VOUTL3&4 = 1.2V; VIN = 3.6V)
Output Current (mA)
Output Voltage Error (%)
-0.4
-0.2
0
0.2
0.4
1000
100
10
10.1
Line Regulation
(VOUTL3&4 = 1.2V)
Input Voltage (V)
Output Voltage Error (%)
-0.4
-0.2
0
0.2
0.4
2.7 3.1 3.5 3.9 4.3 4.7 5.1 5.5
IOUT = 400mA
IOUT = 100mA
IOUT = 10mA
IOUT = 1mA
IOUT = 0.1mA
Output Voltage Error vs. Temperature
(VOUTL3&4 = 2.8V; VIN = 3.6V)
Temperature (°C)
Output Voltage Error (%)
-0.4
-0.2
0
0.2
0.4
856035
10
-15-40
IOUT = 200mA
IOUT = 0.1mA
Load Transient
(VOUTL3&4 = 2.8V; VIN = 3.6V; IOUTL3&4 = 1mA to 50mA)
Time (100µs/div)
Output Voltage
(AC Coupled) (top)
Output Current
(bottom)
-0.02
-0.01
0
0.01
0
0.05
Load Transient
(VOUTL3&4 = 2.8V; VIN = 3.6V; IOUTL3&4 = 1mA to 100mA)
Time (100µs/div)
Output Voltage
AC Coupled) (top)
Output Current
(bottom)
-0.04
-0.02
0
0.02
0
0.1
AAT2603
Total Power Solution for Portable Applications
PRODUCT DATASHEET
2603.2008.06.1.0 15
www.analogictech.com
AAT2603
Total Power Solution for Portable Applications
PRODUCT DATASHEET
2603.2008.06.1.0 15
www.analogictech.com
Typical Characteristics—LDO3/LDO4
Load Transient
(VOUTL3&4 = 2.8V; VIN = 3.6V; IOUTL3&4 = 1mA to 200mA)
Time (100µs/div)
Output Voltage
(AC Coupled) (top)
Output Current
(bottom)
-0.05
0
0.05
0
0.2
Line Transient
(VOUTL3&4 = 2.8V; VIN = 3.6 to 4.2V; IOUTL3&4 = 200mA)
Time (20µs/div)
Input Voltage
(AC Coupled) (top)
Output Voltage
(bottom)
3
4
5
-0.1
-0.05
0
0.05
0.1
0.15
Soft-Start
(VOUTL3&4 = 2.8V; VIN = 3.6V; IOUTL3&4 = 200mA)
Time (500µs/div)
Enable Voltage (top)
Output Voltage
(bottom)
0
2
4
6
0
1
2
3
AAT2603
Total Power Solution for Portable Applications
PRODUCT DATASHEET
16 2603.2008.06.1.0
www.analogictech.com
AAT2603
Total Power Solution for Portable Applications
PRODUCT DATASHEET
16 2603.2008.06.1.0
www.analogictech.com
Functional Block Diagram
DC-DC1
(Buck1)
DC-DC2
(Buck2)
LDO1
LDO2
LDO3
LDO4
Interface
and
Support
INB1
FBB 1
LX2
FBB 2
OUTL 1
OUTL 2
OUTL 3
OUTL 4
FBL 1
FBL 2
FBL 3
FBL 4
INB2
LX1
ENB2
PGND2
PGND1
AGND
BYP
ENL 1
ENL 2
ENL 3
ENL 4
SELB 2
ENB1
INL34
INL12
AIN
Functional Description
The AAT2603 is a highly integrated voltage regulating
power management unit for mobile handsets or other
portable devices. It includes two switch-mode step-down
converters (600mA [DC-DC2] and 1.2A [DC-DC1]), and
four low-dropout (LDO) regulators (two: 200mA, two:
400mA). It operates from an input voltage between 2.7V
and 5.5V making it ideal for lithium-ion or 5V regulated
power sources. All six converters have separate enable
pins for ease of use.
Step-Down Converters
The AAT2603 switch-mode, step-down converters are
constant frequency peak current mode PWM converters
with internal compensation. The input voltage range is
2.7V to 5.5V. The output voltage range is 0.6V to VIN.
The high 1.5MHz switching frequency allows the use of
small external inductor and capacitor.
The step-down converters offer soft-start to limit the
current surge seen at the input and eliminate output
voltage overshoot. The current across the internal
P-channel power switch is sensed and turns off when the
current exceeds the current limit. Also, thermal protec-
tion completely disables switching if internal dissipation
becomes excessive, thus protecting the device from
damage. The junction over-temperature threshold is
140°C with 15°C of hysteresis.
DC-DC1 (Buck1) is designed for a peak continuous out-
put current of 1.2A. The high-side power switch has
been designed with a low RDSON of 145m to allow for a
minimum dropout voltage of 174mV at full load current.
AAT2603
Total Power Solution for Portable Applications
PRODUCT DATASHEET
2603.2008.06.1.0 17
www.analogictech.com
It was designed to maintain over 90% efficiency at its
maximum rated output current load of 1.2A with a 3.3V
output. Peak efficiency is above 95%. Buck1 has excel-
lent transient response, load and line regulation. Transient
response time is typically less than 20s. The peak input
current is limited to 1.7A.
DC-DC2 (Buck2) is a 600mA step-down regulator designed
to dynamically shift between two output voltages by tog-
gling the SELB2 pin. The internal reference voltage of the
buck regulator is changed based on the position of the
SELB2 pin.
Buck2 is designed to maintain over 85% efficiency at its
maximum rated output current of 600mA with a 1.2V
output. Peak efficiency is above 90%. Buck2 has excel-
lent transient response, load and line regulation. The
peak inductor current is limited to 1.3A.
The two step-down converters on the AAT2603 have
highly flexible output voltage programming capability.
The output voltages can be factory programmed to pre-
set output voltages or set by external resistors. The
“Part Number Descriptions” table lists the available volt-
age options for step-down converters Buck1 and Buck2.
Option 1 has externally adjustable output voltages for
both step-down converters. The dynamic voltage scaling
for Buck2 is still useable with external feedback resis-
tors. When SELB2 is in the low position the feedback
voltage is compared to a 600mV reference, while when
SELB2 is high the reference voltage is 775mV. For most
other options, the output voltages of Buck2 are factory
programmed.
LDO Regulators
The AAT2603 includes four LDO regulators. The regula-
tors operate from the 2.7V to 5.5V input voltage to a
regulated output voltage. The LDO regulators have
adjustable output voltages set by resistors. Each LDO
consumes 50uA of quiescent current.
The two 200mA LDO regulators are stable with a small
4.7F ceramic output capacitor. The low 200mV dropout
voltage at 200mA load allows a regulated output voltage
approaching the input voltage. Low output noise voltage
and high power supply rejection make these regulators
ideal for powering noise sensitive circuitry.
The two 400mA LDO regulators are stable with a small
4.7F ceramic output capacitor. The low 300mV dropout
voltage at 400mA load allows a regulated output voltage
approaching the input voltage. These LDOs offer high
power supply rejection.
Application Information
DC-DC1/DC-DC2
The step-down converter uses peak current mode con-
trol 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.
Table 1 displays suggested inductor values 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 satura-
tion 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.
It is recommended that the inductor current rating
exceed the current limit of the step-down converter. See
Table 2 for example inductor values/vendors.
Input Capacitor
Select a 4.7F to 10F X7R or X5R ceramic capacitor for
the input; see Table 3 for suggested capacitor compo-
nents. To estimate the required input capacitor size,
determine the acceptable input ripple level (VPP) and solve
for CIN (CINB1/CINB2). The calculated value varies with input
voltage and is a maximum when VIN is double the output
voltage.
· 1 -
VO
VIN
CIN =
VO
VIN
- ESR · FS
VPP
IO
· 1 - = for VIN = 2 · VO
VO
VIN
VO
VIN
1
4
CIN(MIN) = 1
- ESR · 4 · FS
VPP
IO
Always examine the ceramic capacitor DC voltage coef-
ficient characteristics when selecting the proper value.
For example, the capacitance of a 10F, 6.3V, X5R ceram-
ic capacitor with 5.0V DC applied is actually about 6F.
AAT2603
Total Power Solution for Portable Applications
PRODUCT DATASHEET
18 2603.2008.06.1.0
www.analogictech.com
Confi guration Output Voltage Inductor Value
Adjustable and
Fixed Output
Voltage
1V, 1.2V, 1.3V 1.0H to 1.2H
1.5V, 1.8V 1.5H to 1.8H
2.5V 2.2H to 2.7H
2.8V, 3.3V 3.3H
Table 2: Inductor Values for
Specific Output Voltages.
The maximum input capacitor RMS current is:
IRMS = IO · · 1 -
VO
VIN
VO
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.
· 1 - = D · (1 - D) = 0.52 =
VO
VIN
VO
VIN
1
2
for VIN = 2 · VO
.
Manufacturer
Part Number/
Type
Inductance
(μH)
Rated Current
(A)
DCR (mΩ)
(max)
Size (mm)
LxWxH
TDK LTF5022
1.2 4.3 25
5x5.2x2.2
1.8 3.6 32
2.2 3.2 40
3.3 2.5 60
Wurth Electronik
WE-TPC Type M
1 2.6 30
4.8x4.8x1.8
1.8 2.35 50
2.7 2.03 60
3.3 1.8 65
WE-TPC Type MH
1.2 2.8 20
4.8x4.8x2.8
1.8 2.45 25
2.2 2.35 28
2.7 1.95 30
3.3 1.8 35
Murata LQH55D
1 4 19 (typ)
5x5.7x4.7
1.5 3.7 22 (typ)
2.2 3.2 29 (typ)
3.3 2.9 36 (typ)
Table 1: Suggested Inductor Components.
Manufacturer Part Number Value Voltage Temp. Co. Case
AVX 0603ZD105K 1F10X5R 0603
0603ZD225K 2.2F10
TDK
C1608X5R1E105K 1F25
X5R
0603C1608X5R1C225K 2.2F16
C1608X5R1A475K 4.7F10
C2012X5R1A106K 10F 10 0805
C3216X5R1A226K 22F 10 1206
Murata
GRM188R61C105K 1F16
X5R 0603
GRM188R61A225K 2.2F10
GRM219R61A106K 10F 10 0805
GRM31CR71A226K 22F 10 X7R 1206
Taiyo Yuden LMK107BJ475KA 4.7F 10 X5R 0603
Table 3: Suggested Capacitor Components.
AAT2603
Total Power Solution for Portable Applications
PRODUCT DATASHEET
2603.2008.06.1.0 19
www.analogictech.com
IO
RMS(MAX)
I2
=
The term · 1
-
VO
VIN
VO
VIN appears in both the input voltage ripple
and input capacitor RMS current equations and is a maxi-
mum when V
O
is twice V
IN
. 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 AAT2603 step-
down switching regulators. Low ESR/ESL X7R and X5R
ceramic capacitors are ideal for this function. To mini-
mize stray inductance, the capacitor should be placed as
closely as possible to the IC. This keeps the high fre-
quency content of the input current localized, minimizing
EMI and input voltage ripple.
A laboratory test set-up typically consists of two long
wires running from the bench power supply to the eval-
uation 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 dur-
ing 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 induc-
tance cannot be reduced to a level that does not affect
the converter performance, a high ESR tantalum or alu-
minum electrolytic should be placed in parallel with the
low ESR, ESL bypass ceramic. This dampens the high Q
network and stabilizes the system.
Output Capacitor
The output capacitor limits the output ripple and provides
holdup during large load transitions. A 10F to 22F X5R
or X7R ceramic capacitor typically provides sufficient bulk
capacitance to stabilize the output during large load tran-
sitions and has the ESR and ESL characteristics neces-
sary for low output ripple. A 10F X5R or X7R ceramic
capacitor is required for DC-DC2 and a 22F X5R or X7R
ceramic capacitor is required for DC-DC1; see Table 3 for
suggested capacitor components.
The output voltage droop due to a load transient is dom-
inated 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 several switching cycles, the loop
responds and the inductor current increases to match the
load current demand. The relationship of the output volt-
age droop during the several switching cycles to the out-
put 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 equa-
tion 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 10F for DC-DC2 and
22F for DC-DC1. 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:
1
23
VOUT · (VIN(MAX) - VOUT)
RMS(MAX)
IL · 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.
Feedback Resistor Selection
Resistors R1 and R2 of Figure 1 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 minimum
suggested value for R2 is 59kΩ. Although a larger value
will further reduce quiescent current, it will also increase
the impedance of the feedback node, making it more
sensitive to external noise and interference. Table 42
summarizes the resistor values for various output volt-
ages with R2 set to either 59kΩ for good noise immu-
nity or 221kΩ for reduced no load input current.
AAT2603
Total Power Solution for Portable Applications
PRODUCT DATASHEET
20 2603.2008.06.1.0
www.analogictech.com
R1 = -1 · R2 = - 1 · 59kΩ = 88.5kΩ
VOUT
VREF
1.5V
0.6V
The AAT2603 step-down regulators, combined with an
external feedforward capacitor (CFF in Figure 1), deliver
enhanced transient response for extreme pulsed load
applications.
V
FBB1
/V
FBB2
V
DC-DC1
/V
DC-DC2
R1
R2
CFF
Figure 1: AAT2603 DC-DC1/DC-DC2 External
Resistor Output Voltage Programming.
VOUT (V)
R2 = 59kΩ
R1 (kΩ)
R2 = 221kW
R1 (kΩ)
0.9 29.4 113K
1.0 39.2 150K
1.1 49.9 187K
1.2 59.0 221K
1.3 68.1 261K
1.4 78.7 301K
1.5 88.7 332K
1.8 118 442K
1.85 124 464K
2.0 137 523K
2.5 187 715K
3.3 267 1.00M
Table 4: Feedback Resistors
for DC-DC1 and DC-DC2.
LDO1/LDO2/LDO3/LDO4
Input Capacitor
Typically, a 2.2F or larger capacitor is recommended for
CINL12/CINL34/CAIN in most applications. The input capacitor
should be located as close to the input (INL12/INL34/
AIN) of the device as practically possible. CINL12/CINL34/
CAIN values greater than 2.2F will offer superior input
line transient response and will assist in maximizing the
highest possible power supply ripple rejection.
Ceramic, tantalum, or aluminum electrolytic capacitors
may be selected for CINL12/CINL34/CAIN. There is no specific
capacitor ESR requirement for CINL12/CINL34/CAIN. However,
for 200mA/400mA LDO regulators output operation,
ceramic capacitors are recommended for CINL12/CINL34/CAIN
due to their inherent capability over tantalum capacitors
to withstand input current surges from low impedance
sources such as batteries in portable devices.
Output Capacitor
For proper load voltage regulation and operational stabil-
ity, a capacitor is required between pins VOUTLX and
AGND. The COUTLX capacitor connection to the LDO regu-
lator ground pin should be made as direct as practically
possible for maximum device performance.
The AAT2603 LDO regulators have been specifically
designed to function with very low ESR ceramic capaci-
tors. Although the device is intended to operate with
these low ESR capacitors, it is stable over a very wide
range of capacitor ESR, thus it will also work with higher
ESR tantalum or aluminum electrolytic capacitors.
However, for best performance, ceramic capacitors are
recommended.
Typical output capacitor values for maximum output cur-
rent conditions range from 4.7F to 10F. If desired,
COUTLX may be increased without limit.
Bypass Capacitor and Low Noise Applications
A bypass capacitor pin is provided to enhance the very
low noise characteristics of the AAT2603 LDO3 and LDO4
regulators. The bypass capacitor is not necessary for
operation of the AAT2603. However, for best device per-
formance, a small ceramic capacitor should be placed
between the bypass pin (BYP) and the device analog
ground pin (AGND). The value of CBYP should be 10nF. For
lowest noise and best possible power supply ripple rejec-
tion performance a 10nF capacitor should be used. To
practically realize the highest power supply ripple rejec-
tion and lowest output noise performance, it is critical
that the capacitor connection between the BYP pin and
AGND pin be direct and PCB traces should be as short as
possible. Refer to the PCB Layout Recommendations sec-
tion of this datasheet for examples.
AAT2603
Total Power Solution for Portable Applications
PRODUCT DATASHEET
2603.2008.06.1.0 21
www.analogictech.com
There is a relationship between the bypass capacitor
value and the LDO regulator turn-on time. In applica-
tions where fast device turn-on time is desired, the
value of CBYP should be reduced.
In applications where low noise performance and/or
ripple rejection are less of a concern, the bypass capac-
itor may be omitted. The fastest device turn-on time will
be realized when no bypass capacitor is used.
DC leakage on this pin can affect the LDO regulator output
noise and voltage regulation performance. For this rea-
son, the use of a low leakage, high quality ceramic (NPO
or C0G type) or film capacitor is highly recommended.
Feedback Resistor Selection
Resistors R1 and R2 of Figure 2 program the output to
regulate at a voltage higher than 1.5V for LDO1/LDO2
and 1.2V for LDO3/LDO4. To limit the bias current
required for the external feedback resistor string while
maintaining good noise immunity, the minimum sug-
gested value for R2 is 100kΩ. Although a larger value
will further reduce quiescent current, it will also increase
the impedance of the feedback node, making it more
sensitive to external noise and interference. Tables 5
and 6 summarize the resistor values for various output
voltages with R2 set to 100kΩ.
R1 = -1 · R2 = - 1 · 100kΩ = 24.9kΩ
VOUT
VREF
1.5V
1.2V
V
FBLX
V
OUTLX
R1
R2
Figure 2: AAT2603 LDO1/LDO2/LDO3/LDO4
External Resistor Output Voltage Programming.
VOUT (V)
R2 = 100kΩ
R1 (kΩ)
1.3 8.25
1.4 16.5
1.5 24.9
1.6 33.2
1.7 41.2
1.8 49.9
1.9 59
2 66.5
2.1 75
2.2 82.5
2.3 90.9
2.4 100
2.5 107
2.6 118
2.7 124
2.8 133
2.9 140
3 150
3.1 158
3.2 165
3.3 174
Table 5: Feedback Resistor Values
for LDO3 and LDO4.
VOUT (V)
R2 = 100kΩ
R1 (kΩ)
1.5 24.9
1.6 33.2
1.7 41.2
1.8 49.9
1.9 59
2 66.5
2.1 75
2.2 82.5
2.3 90.9
2.4 100
2.5 107
2.6 118
2.7 124
2.8 133
2.9 140
3 150
3.1 158
3.2 165
3.3 174
Table 6: Feedback Resistor Values
for LDO1 and LDO2.
AAT2603
Total Power Solution for Portable Applications
PRODUCT DATASHEET
22 2603.2008.06.1.0
www.analogictech.com
Thermal Calculations
There are three types of losses associated with the
AAT2603 total power management solution [two step-
down and four LDO regulators]: switching losses, con-
duction losses, and quiescent current losses. Conduction
losses are associated with the RDS(ON) characteristics of
the internal power switches/FETs of both of the step-
down regulators and the power loss associated with the
voltage difference across the pass switch/FET of the four
LDO regulators. 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 the following
(quiescent and switching losses are ignored, since con-
duction losses are so dominant):
PDC-DC1
IO1
2 · (RDS(ON)H1 · VOB1 + RDS(ON)L1 · [VINB1 - VOB1])
VINB1
=
PDC-DC2
IO2
2 · (RDS(ON)H2 · VOB2 + RDS(ON)L2 · [VINB2 - VOB2])
VINB2
=
PLDO1 = ILDO1 · (VINL12 - VOL1)
PLDO2 = ILDO2 · (VINL12 - VOL2)
PLDO3 = ILDO3 · (VINL34 - VOL3)
PLDO4 = ILDO4 · (VINL34 - VOL4)
PTOTAL = PDC_DC1 + PDC_DC2 + PLDO1 + PLDO2 + PLDO3 + PLDO4
PDC-DCX: Power dissipation of the specific DC-DC
regulator
IOX: Output current of the specific DC-DC regulator
RDS(ON)HX: Resistance of the internal high-side switch/FET
RDS(ON)LX: Resistance of the internal low-side switch/FET
VOBX: Output voltage of the specific DC-DC regulator
VINBX: Input voltage of the specific DC-DC regulator
PLDOX: Power dissipation of the specific LDO regulator
ILDOX: Output current of the specific LDO regulator
VINLXX: Input voltage of the specific LDO regulator
VOLX: Output voltage of the specific LDO regulator
PTOTAL: Total power dissipation of the AAT2603
Since RDS(ON) and conduction losses all vary with input
voltage, the dominant losses should be investigated over
the complete input voltage range. Given the total con-
duction losses, the maximum junction temperature
(125°C) can be derived from the JA for the TQFN44-28
package which is 50°C/W.
TJ(MAX) = PTOTAL · θJA + TA
TJ(MAX): Maximum junction temperature
P
TOTAL: Total conduction losses
JA: Thermal impedance of the package
TA: Ambient temperature
Layout
The suggested PCB layout for the AAT2603 is shown in
Figures 4 and 5. The following guidelines should be used
to help ensure a proper layout.
1. The input capacitors (C1, C2, C7, C13, and C16)
should connect as closely as possible to INB1 (Pin
26), INB2 (Pin 27), AIN (Pin 20), INL12 (Pin 16),
INL34 (Pin 8), and AGND/PGND1/PGND2 (Pins 5,
25, and 27).
2. C3/C18 (step-down regulator output capacitors) and
L1/L2 should be connected as closely as possible.
The connection of L1/L2 to the LX1/LX2 pins should
be as short as possible.
3. The feedback trace or FBXX pin (Pins 3, 6, 10, 14,
18, and 21) 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. If external feedback
resistors are used, they should be placed as closely
as possible to the FBXX pin (Pins 3, 6, 10, 14, 18,
and 21) to minimize the length of the high imped-
ance feedback trace.
4. The resistance of the trace from the load return to
the PGND1/PGND2 (Pins 25 and 28) should be kept
to a minimum. This will help to minimize any error
in DC regulation due to differences in the potential
of the internal signal ground and the power ground.
5. For good thermal coupling, PCB vias are required
from the pad for the TDFN44-28 exposed paddle to
the ground plane.
AAT2603
Total Power Solution for Portable Applications
PRODUCT DATASHEET
2603.2008.06.1.0 23
www.analogictech.com
AAT2603
Total Power Solution for Portable Applications
PRODUCT DATASHEET
2603.2008.06.1.0 23
www.analogictech.com
LX2
1
ENB2
2
FBB2
3
ENL3
4
AGND
5
FBL3
6
OUTL3
7
INL34 8
OUTL4 9
FBL 4 10
ENL4 11
BYP 12
ENL1 13
FBL1 14
OUTL1 15
INL12 16
OUTL2 17
FBL2 18
ENL2 19
AIN 20
FBB1 21
ENB1
22
SEL B2
23
LX1
24
PGND1
25
INB1
26
INB2
27
PGND2
28
AAT2603
U1
C1
R1
C13
C17
C7
C5
C3
C18
C4
C8
R11
R9
R2
R12
R10
R8
R5
R6
R7
R4
R3
L2
L1
C11
C15
C16
C14
C10
C12
C9
C6
GND
GND
ENB2
ENL1
ENL3
VIN
SELB2
GND
VIN
VIN
ENL2
ENB1
ENL4
VIN
OUTB1
OUTB2
OUTL1
OUTL2
OUTL3
OUTL4
C2
1
3
2
3-Prong Header 3-Prong Header
J1
3-Prong Header
J3
1
3
2
J2
3-Prong Header
J4
3-Prong Header
J5
3-Prong Header
J7
3-Prong Header
J6
1
3
2
1
3
2
1
3
2
1
3
2
VIN
GND
ENL1 ENB1
ENL2 ENB2
ENL3 ENL4
1
3
2SELB2
Figure 3: AAT2603 Evaluation Board Schematic.
AAT2603
Total Power Solution for Portable Applications
PRODUCT DATASHEET
24 2603.2008.06.1.0
www.analogictech.com
Figure 4: AAT2603 Evaluation Board Top Side PCB Layout.
Figure 5: AAT2603 Evaluation Board Bottom Side PCB Layout.
AAT2603
Total Power Solution for Portable Applications
PRODUCT DATASHEET
2603.2008.06.1.0 25
www.analogictech.com
AAT2603
Total Power Solution for Portable Applications
PRODUCT DATASHEET
2603.2008.06.1.0 25
www.analogictech.com
Ordering Information
Package
Output Voltage1
Marking2Part Number (Tape and Reel)3
DC-DC1
(Buck1)
DC-DC2 (Buck2)
(SELB2 = Low)
DC-DC2 (Buck2)
(SELB2 = High)
TQFN44-28 Ext. Adj.
(VREF = 600mV)
Ext. Adj.
(VVREF = 600mV)
Ext. Adj.
(VVREF= 775mV) 3AXYY AAT2603INJ-1-T1
TQFN44-28 3.3V 1.0V 1.3V AAT2603INJ-2-T1
TQFN44-28 Ext. Adj.
(VREF = 600mV) 1.0V 1.3V AAT2603INJ-3-T1
All AnalogicTech products are offered in Pb-free packaging. The term “Pb-free” means semiconductor
products that are in compliance with current RoHS standards, including the requirement that lead not exceed
0.1% by weight in homogeneous materials. For more information, please visit our website at
http://www.analogictech.com/about/quality.aspx.
1. Buck 1 and Buck 2 output voltages can be factory programmed to most common output voltages. Contact your local sales representative for availability and minimum order
quantities.
2. XYY = assembly and date code.
3. Sample stock is generally held on part numbers listed in BOLD.
AAT2603
Total Power Solution for Portable Applications
PRODUCT DATASHEET
26 2603.2008.06.1.0
www.analogictech.com
AAT2603
Total Power Solution for Portable Applications
PRODUCT DATASHEET
26 2603.2008.06.1.0
www.analogictech.com
Advanced Analogic Technologies, Inc.
3230 Scott Boulevard, Santa Clara, CA 95054
Phone (408) 737-4600
Fax (408) 737-4611
© Advanced Analogic Technologies, Inc.
AnalogicTech cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in an AnalogicTech product. No circuit patent licenses, copyrights, mask work rights, or other intellectual
property rights are implied. AnalogicTech reserves the right to make changes to their products or specifi cations or to discontinue any product or service without notice. Except as provided in AnalogicTech’s terms and
conditions of sale, AnalogicTech assumes no liability whatsoever, and AnalogicTech disclaims any express or implied warranty relating to the sale and/or use of AnalogicTech products including liability or warranties
relating to fi tness for a particular purpose, merchantability, or infringement of any patent, copyright or other intellectual property right. In order to minimize risks associated with the customer’s applications, adequate
design and operating safeguards must be provided by the customer to minimize inherent or procedural hazards. Testing and other quality control techniques are utilized to the extent AnalogicTech deems necessary to
support this warranty. Specifi c testing of all parameters of each device is not necessarily performed. AnalogicTech and the AnalogicTech logo are trademarks of Advanced Analogic Technologies Incorporated. All other
brand and product names appearing in this document are registered trademarks or trademarks of their respective holders.
Package Information
TQFN44-28
4.000
±
0.050
4.000
±
0.050
Pin 1 Dot
by Marking
Top View
2.600 ± 0.050
2.600 ± 0.050
Bottom View
Detail "A"
0.750 ± 0.050
0.050 ± 0.050
0.203 REF
Side View
0.400 ± 0.050
0.230
±
0.050
0.430
±
0.050
Pin 1 Indicator
Detail "A"
C0.3
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.
