Analogic AAT2503 Adjustable 3-channel regulator Datasheet

PRODUCT DATASHEET
AAT2503178
SystemPowerTM
Adjustable 3-Channel Regulator
General Description
Features
The AAT2503 is a three-channel regulator consisting of a
step-down converter with an input voltage range of 2.7V
to 5.5V plus two low dropout (LDO) linear regulators.
• 800mA Step-Down Converter
▪ VIN Range: 2.7V to 5.5V
▪ VOUT Range: 0.9V to VIN
▪ High Efficiency
▪ 2MHz Switching Frequency
• Two 150mA Low Dropout Regulators
▪ LDO Input Voltage Range: 1.62V to 5.5V
▪ VOUT Range: 0.6V to VIN
▪ High Output Accuracy: ±1.5%
• 85μA of Total IQ
• Independent Enable Pins
• Integrated Power MOSFETs
• Over-Temperature Protection
• QFN34-20 Package
• -40°C to +85°C Temperature Range
The step-down converter optimizes power efficiency
throughout the load range. Pulling the MODE/SYNC pin
high enables “PWM Only” mode, maintaining constant
frequency and low output ripple across the operating
range. Alternatively, the converter may be synchronized
to an external clock input to the MODE/SYNC pin. The
step-down converter delivers up to 800mA of output current, while consuming 30μA of typical no load quiescent
current. The switching frequency is 2MHz, minimizing
the size of external components.
The two LDOs (LDOA/LDOB) have independent inputs
and are capable of delivering up to 150mA each. Ultra
low input voltage on the VLDOA and VLDOB pins (down
to 1.62V) allows for efficient post-buck regulation. A
Power-OK (POK) function provides an open drain output
signal when LDOA is within regulation. Both LDOs feature low quiescent current and a low dropout voltage.
The output voltages for both LDOs are adjustable to as
low as 0.6V. The linear regulators have independent
Enable pins.
Applications
•
•
•
•
•
Cellular Phones
Digital Cameras
Handheld Instruments
Microprocessor/DSP Core/IO Power
PDAs and Handheld Computers
The AAT2503 is available in a Pb-free 3x4mm QFN34-20
package and is rated over the -40°C to +85°C temperature range.
Typical Application
L1
LX
AAT2503
VIN
VIN
VLDOA
VLDOB
VP
MODE/SYNC
EN
2503.2008.02.1.4
R1
OUTA
R3
100kΩ
POK
R4
OUTA
C2
10μF
POK
FBA
OUTB
OUTB
R5
FBB
ENA
ENB
VOUT (Buck)
FB
R8
C6
2.2μF
R7
C5
2.2μF
R2
PGND
AGND
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1
PRODUCT DATASHEET
AAT2503178
SystemPowerTM
Adjustable 3-Channel Regulator
Pin Descriptions
Pin #
Symbol
1
FBB
2
ENA
3
ENB
4
MODE/SYNC
5
FB
6
7
AGND
PGND
8, 9
LX
10
11, 12
VP
N/C
13
VIN
14
EN
15
POK
16
FBA
17
18
19
20
EP
OUTA
VLDOA
VLDOB
OUTB
2
Function
Feedback input pin for LDOB. This pin is connected to OUTB via an external resistor. It is used to see the
output of LDOB to regulate to the desired value via an external resistor divider. For fixed versions, short
FBB to OUTB.
Enable pin for LDOA. When connected low, LDOA is disabled and consumes less than 1μA of current. When
connected high, normal operation.
Enable pin for LDOB. When connected low, LDOB is disabled and consumes less than 1μA of current. When
connected high, normal operation.
Connect to ground for PWM/PFM mode and optimized efficiency throughout the load range. Connect high
for low noise PWM operation under all operating conditions. Connect to an external clock for synchronization (PWM only).
Feedback input pin for the step-down converter. This pin is connected to the converter output via an external resistor. It is used to see the output of the converter to regulate to the desired value via an external
resistor divider.
Ground connection pin.
Main power ground return pin for the step-down converter. Connect to the output and input capacitor return.
Connect inductor to this pin. Switching node internally connected to the drain of both high- and low-side
MOSFETs.
Input supply voltage for the converter. Must be closely decoupled.
Not connected.
Bias supply. Supply power for the internal circuitry. Connect to input power via low pass filter with decoupling to AGND.
Enable for the step-down converter. A logic low disables the converter and it consumes less than 1μA of
current. A logic high enables normal operation.
Power-OK pin with open drain output. It is pulled low when the OUTA pin is outside the regulation window.
Place a pull-up resistor between POK and OUTA.
Feedback input pin for LDOA. This pin is connected to OUTA via an external resistor. It is used to see the
output of LDOA to regulate to the desired value via an external resistor divider. For fixed versions, short
FBA to OUTA.
LDOA output pin; should be closely decoupled with a low-ESR ceramic capacitor.
Input voltage pin for linear regulator A; should be closely decoupled.
Input voltage pin for linear regulator B; should be closely decoupled.
LDOB output pin; should be closely decoupled with a low-ESR ceramic capacitor.
Exposed paddle; connect to ground directly beneath the package.
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2503.2008.02.1.4
PRODUCT DATASHEET
AAT2503178
SystemPowerTM
Adjustable 3-Channel Regulator
Pin Configuration
QFN34-20
(Top View)
OUTA
VLDOA
VLDOB
OUTB
17
18
19
20
FBB
ENA
ENB
MODE/SYNC
FB
AGND
1
16
2
15
3
14
4
13
5
12
6
11
FBA
POK
EN
VIN
N/C
N/C
9
10
8
7
VP
LX
LX
PGND
Absolute Maximum Ratings1
Symbol
VP, VIN, VLDO
VLX
VFB
VN
TJ
TLEAD
Description
Input Voltage and Bias Power to GND
LX to GND
FB to GND
EN, MODE/SYNC to GND
Operating Junction Temperature Range
Maximum Soldering Temperature (at leads, 10 sec)
Value
Units
6.0
-0.3 to VP + 0.3
-0.3 to VP + 0.3
-0.3 to 6.0
-40 to 150
300
V
V
V
V
°C
°C
Value
Units
2.0
50
W
°C/W
Thermal Information
Symbol
PD
θJA
Description
Maximum Power Dissipation (TA = 25°C)
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.
2503.2008.02.1.4
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3
PRODUCT DATASHEET
AAT2503178
SystemPowerTM
Adjustable 3-Channel Regulator
Electrical Characteristics1
VIN = 3.6V; TA = -40°C to +85°C, unless otherwise noted. Typical values are TA = 25°C.
Symbol
Description
Conditions
Bias Power Supply
IQ
Quiescent Current
ISHDN
Shutdown Current
LDOA, LDOB; IOUT = 150mA
VLDO
Input Voltage
VOUT
VFB
VDO
ΔVOUT/
VOUT*ΔVIN
VEN(L)
VEN(H)
IOUT
ISHT
TSD
THYS
LDOA; IOUT
VPOK
VPOKHYS
VPOK(LO)
IPOK
Min
ENA = ENB = EN = VIN; ILOAD = 0
ENA = ENB = EN = GND
IOUT = 1mA
to 150mA
Output Voltage Tolerance
TA = 25°C
TA = -40°C to +85°C
Feedback Voltage
Dropout Voltage2
IOUT = 150mA
Line Regulation3
VIN = VOUT + 1 to 5.0V
Enable Threshold Low
Enable Threshold High
Output Current
Shutdown Current
Over-Temperature Shutdown Threshold
Over-Temperature Shutdown Hysteresis
= 150mA
Power-OK Trip Threshold
Power-OK Hysteresis
Power-OK Output Voltage Low
Power-OK Output Leakage Current
1.62
-1.5
-2.5
0.593
Typ
Max
Units
85
145
1.0
μA
μA
5.5
1.5
2.5
0.607
150
V
%
V
mV
0.09
%/V
0.6
V
V
mA
μA
°C
°C
0.6
1.4
150
VIN = 5V
1.0
140
15
VOUT Rising, TA = 25°C
ISINK = 1mA
VPOK <5.5V, VOUT in Regulation
80
90
1.0
98
0.4
1.0
% of VOUT
% of VOUT
V
μA
1. The AAT2503 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. CIN = 10μF.
4
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2503.2008.02.1.4
PRODUCT DATASHEET
AAT2503178
SystemPowerTM
Adjustable 3-Channel Regulator
Electrical Characteristics (continued)1
VIN = 3.6V; TA = -40°C to +85°C, unless otherwise noted. Typical values are TA = 25°C.
Symbol
Description
Conditions
Min
Typ
Max
Units
5.5
1.8
1.2
400
300
0.5
V
V
mV
V
%
V
V
μA
μA
μA
A
mΩ
mΩ
%
0.2
%/V
Step-Down Converter; IOUT = 800mA
VIN
UVLO
Under-Voltage Lockout Voltage
VOUT
VOUT
VFB
ISHDN
Output Voltage Tolerance
VOUT Programmable Range
Feedback Threshold Voltage
Shutdown Current
LX Leakage Current
Feedback Leakage
Current Limit
High Side Switch On Resistance
Low Side Switch On Resistance
Load Regulation
ILX_LEAK
IFB
ILIM
RDS(ON)H
RDS(ON)L
ΔVOUT/VOUT
ΔVOUT/
VOUT*ΔVIN
FOSC
TSD
THYS
VEN(L)
VEN(H)
IEN
VMODE/SYNC(L)
VMODE/SYNC(H)
IMODE/SYNC
2.7
Input Voltage
VIN Rising
Hysteresis
VIN Falling
IOUT = 0 to 800mA; VIN = 2.7V to 5.5V
250
1.5
-3.0
0.9
0.891
0.9
EN = GND
VIN = 5.5, VLX = 0 to VIN
VFB = 1.0V
ILOAD = 0 to 800mA
Line Regulation
Oscillator Frequency
Over-Temperature Shutdown Threshold
Over-Temperature Shutdown Hysteresis
Enable Threshold Low
Enable Threshold High
EN Input Leakage
Enable Threshold Low
Enable Threshold High
Input Low Current
1.6
2.0
140
15
3.0
VIN
0.909
1.0
1.0
0.2
2.4
0.6
VEN = 5V, VIN = 5V
1.4
-1.0
VIN · 0.7
-1.0
1.0
VIN · 0.4
1.0
MHz
°C
°C
V
V
μA
V
V
μA
1. The AAT2503 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.
2503.2008.02.1.4
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5
PRODUCT DATASHEET
AAT2503178
SystemPowerTM
Adjustable 3-Channel Regulator
Typical Characteristics—Step-Down Converter
Efficiency vs. Output Current
Efficiency vs. Output Current
(VOUT = 1.8V; L = 2.2µH)
90
100
80
90
VIN = 2.7V
60
50
VIN = 3.6V
40
PWM Only
Mode
VIN = 4.2V
30
20
70
VIN = 2.7V
60
50
PWM Only
Mode
40
VIN = 4.2V
30
20
10
10
0
0
0
1
10
100
0
1000
Switching Frequency vs. Temperature
(VIN = 3.6V; IOUT = 800mA)
2.4
2.3
Frequency (MHz)
VIN = 3.3V
70
60
VIN = 3.6V
PWM Only
Mode
40
VIN = 4.2V
VOUT = 0.9V
2.2
2.1
VOUT = 1.8V
2.0
1.9
1.8
VOUT = 2.5V
1.7
1.6
10
0
0
1
10
100
1000
1.5
-40
-20
0
20
40
60
Load Regulation
Soft Start
(VOUT = 1.8V; VMODE/SYNC = VIN; L = 2.2µH)
(VIN = 3.6V; VOUT = 1.8V; IOUT = 800mA)
6.0
0.9
4.0
0.6
VIN = 4.2V
0.0
-0.3
100
VIN = 3.3V VIN = 3.6V
-0.6
-0.9
ENABLE
1.8V
2.0
0.0
VOUT
0V
1.0
0.5
IINDUCTOR
Inductor Current
(Bottom) (A)
ENABLE and VOUT
(Top and Middle) (V)
1.2
0.3
80
Temperature (°°C)
Output Current (mA)
0.0
-1.2
-0.5
0
1
10
100
1000
Time (100µs/div)
Output Current (mA)
6
1000
(VOUT = 2.5V; L = 3.3µH)
20
Accuracy (%)
100
Efficiency vs. Output Current
90
30
10
Output Current (mA)
100
50
1
Output Current (mA)
80
Efficiency (%)
VIN = 3.6V
80
70
Efficiency (%)
Efficiency (%)
(VOUT = 0.9V; L = 1µH)
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2503.2008.02.1.4
PRODUCT DATASHEET
AAT2503178
SystemPowerTM
Adjustable 3-Channel Regulator
Typical Characteristics—Step-Down Converter
Turn Off
Line Regulation
(VIN = 3.6V; VOUT = 1.8V; IOUT = 800mA)
(VOUT = 1.8V; VMODE/SYNC = VIN)
1.2
6.0
ENABLE
2.0
0.0
VOUT (1V/div)
1.8V
1.0
0V
IINDUCTOR
0.5
Accuracy (%)
0.9
Inductor Current
(Bottom) (A)
ENABLE and VOUT
(Top and Middle) (V)
4.0
0.6
0.3
IL = 800mA
0.0
-0.3
IL = 10mA
0.0
-0.9
-0.5
-1.2
2.7
3.1
3.5
Time (100µs/div)
4.3
4.7
5.1
Line Regulation
No Load Quiescent Current vs. VIN
(VOUT = 0.9V; VMODE/SYNC = VIN)
(VOUT = 1.8V; L = 2.2µH)
5.5
Quiescent Current (µA)
65
0.9
Accuracy (%)
3.9
Input Voltage (V)
1.2
0.6
IL = 800mA
0.3
0.0
-0.3
IL = 650mA
-0.6
-0.9
-1.2
60
55
TA = 85°C
50
45
TA = 25°C
40
35
TA = -40°C
30
25
2.7
3.1
3.5
3.9
4.3
4.7
5.1
5.5
2.7
3.1
3.5
Input Voltage (V)
3.9
4.3
4.7
5.1
5.5
Input Voltage (V)
No Load Quiescent Current vs. VIN
Output Voltage Error vs. Temperature
(VOUT = 0.9V; L = 1µH)
(VIN = 3.6V; VOUT = 0.9V; IOUT = 800mA)
50
2.0
Output Voltage Error (%)
Quiescent Current (µA)
IL = 100mA
-0.6
45
TA = 85°C
40
35
TA = 25°C
30
TA = -40°C
25
20
2.7
3.1
3.5
3.9
4.3
4.7
5.1
5.5
1.5
VIN = 2.5V
0.5
0.0
-0.5
-1.0
VOUT = 0.9V
-1.5
-2.0
-40
-20
0
20
40
60
80
100
Temperature (°°C)
Input Voltage (V)
2503.2008.02.1.4
VIN = 1.8V
1.0
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7
PRODUCT DATASHEET
AAT2503178
SystemPowerTM
Adjustable 3-Channel Regulator
Line Transient
Load Transient
(VOUT = 1.8V; IOUT = 800mA; VIN = 3.6V to 4.2V)
(VIN = 3.6V; VOUT = 1.8V; IOUT = 300mA to 650mA)
2.2
2.4
2.0
4.0
2.3
3.5
2.2
3.0
2.1
2.5
2.0
2.0
1.9
1.5
1.8
1.0
1.7
Output Voltage
(top) (V)
2.5
4.5
1.8
1.6
VOUT
IOUT
300mA
1.2
1.0
0.5
1.6
0.8
0.0
1.5
0.6
0.6
IINDUCTOR
Light Load Output Ripple
Heavy Load Output Ripple
(VIN = 3.6V; VOUT = 1.8V; IOUT = 800mA)
1.0
0
0.8
-10
0.6
-20
0.4
-30
IINDUCTOR
-40
0.0
-50
-0.2
-60
1.8
1.6
Inductor Current
(Bottom) (A)
10
Time (10µs/div)
8
20
10
VOUT
1.4
0
1.2
-10
1.0
-20
0.8
-30
0.6
0.4
-40
IINDUCTOR
-50
0.2
-60
Output Voltage (AC coupled)
(Top) (mV)
20
VOUT
Output Voltage (AC coupled)
(Top) (mV)
Inductor Current
(Bottom) (A)
Time (20µs/div)
(VIN = 2.7V; VOUT = 1.8V; IOUT = 1mA)
1.4
0.2
0.3
0.0
Time (20µs/div)
1.2
650mA
1.4
Load and Inductor Current
(Bottom) (A)
5.0
Output Voltage
(bottom) (V)
Input Voltage
(top) (V)
Typical Characteristics—Step-Down Converter
Time (200ms/div)
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2503.2008.02.1.4
PRODUCT DATASHEET
AAT2503178
SystemPowerTM
Adjustable 3-Channel Regulator
Typical Characteristics—LDO Regulator
Dropout Voltage vs. Temperature
Dropout Voltage vs. Output Current
(VOUT = 2.8V)
(VOUT = 2.8V)
100
150mA
100
80
Dropout Voltage (mV)
Dropout Voltage (mV)
120
100mA
60
50mA
40
20
90
85°C
80
70
25°C
60
50
40
30
-40°C
20
10
0
0
-40
-20
0
20
40
60
80
100
0
120
20
40
60
80
100
120
140
160
Temperature (°°C)
Output Current (mA)
Dropout Characteristics
LDO Output Voltage vs. LDO Input Voltage
Output Voltage (V)
3.0
10mA
2.9
1mA
2.8
150mA
100mA
2.7
2.6
50mA
2.5
2.4
2.7
2.8
2.9
3.0
3.1
3.2
LDO Output Voltage (VOUTA) (V)
(IOUTA = 100mA, VIN = VP = 3.6V)
1.90
1.85
1.80
1.75
1.70
1.65
1.60
1.55
1.50
1.45
1.40
1.35
1.30
VOUTA = 1.8V
VOUTA = 1.5V
1.6
1.7
2.2
DC Regulation
(VIN = 3.6V; VOUT = 1.8V)
2.5
2.0
DC Regulation (%)
DC Regulation (%)
2.1
DC Regulation
2.0
1.5
1.0
0.5
IOUT = 50mA
0.0
-0.5
IOUT = 1mA
-1.0
IOUT = 100mA
-1.5
-2.0
0
20
40
2.3
2.4
2.5
60
1.5
1.0
IOUT = 50mA
0.5
80
100
IOUT = 1mA
0.0
-0.5
-1.0
IOUT = 150mA
-1.5
IOUT = 100mA
-2.0
IOUT = 150mA
-2.5
-2.5
-40
Temperature (°°C)
2503.2008.02.1.4
2.0
(VIN = 3.6V; VOUT = 1.2V)
2.5
-20
1.9
LDO Input Voltage (VLDOA/B) (V)
Input Voltage (V)
-40
1.8
-20
0
20
40
60
80
100
Temperature (°°C)
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PRODUCT DATASHEET
AAT2503178
SystemPowerTM
Adjustable 3-Channel Regulator
Typical Characteristics—LDO Regulator
DC Regulation
Quiescent Current vs. Input Voltage
(VIN = 3.6V; VOUT = 2.8V)
(VLDO = 2.8V)
2.5
35
1.5
1.0
IOUT = 50mA
0.5
0.0
-0.5
IOUT = 1mA
-1.0
IOUT = 100mA
-1.5
IOUT = 150mA
-2.0
-2.5
-40
-20
0
20
40
60
80
100
Ground Current (µA)
DC Regulation (%)
2.0
IOUT = 150mA IOUT = 50mA
31
IOUT = 100mA
27
IOUT = 0mA
23
19
15
2.7
3.5
3.9
4.3
4.7
Turn-On Response Time
Turn-Off Response Time
(VIN = 3.6V; VOUT = 1.8V; IOUT = 150mA)
(VIN = 3.6V; VOUT = 1.8V; IOUT = 150mA)
5.1
5.5
6
7
6
4
6
2
5
2
5
0
4
0
4
-2
3
-2
3
-4
2
-4
2
-6
1
-6
1
-8
0
-8
0
-10
-1
-10
-1
ENABLE
(Top ) (V)
7
4
Output Voltage
(Bottom) (V)
6
Time (10µs/div)
Time (50µs/div)
Load Transient
Load Transient
(VIN = 3.6V; VOUT = 1.8V; IOUT = 1mA to 100mA)
(VIN = 3.6V; VOUT = 1.8V; IOUT = 50mA to 100mA)
2.2
0.7
0.6
2.0
0.6
1.8
0.5
1.8
0.5
1.6
0.4
1.6
0.4
1.4
0.3
1.4
0.3
1.2
0.2
Output Voltage
(Top) (V)
0.7
2.0
1.2
0.2
1.0
0.1
1.0
0.1
0.8
0.0
0.8
0.0
0.6
-0.1
0.6
-0.1
Time (200µs/div)
Output Current
(Bottom) (A)
2.2
Output Current
(Bottom) (A)
Output Voltage
(top) (V)
3.1
Input Voltage (V)
Output Voltage
(Bottom) (V)
ENABLE
(Top ) (V)
Temperature (°°C)
10
IOUT = 10mA
Time (50µs/div)
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2503.2008.02.1.4
PRODUCT DATASHEET
AAT2503178
SystemPowerTM
Adjustable 3-Channel Regulator
Typical Characteristics—LDO Regulator
5.0
2.6
5.0
4.5
2.5
4.5
2.4
4.0
2.3
3.5
2.2
3.0
2.1
2.5
2.0
2.0
1.9
Input Voltage
(top) (V)
VIN
3.5
2.3
3.0
2.2
2.5
2.1
2.0
2.0
1.5
1.9
1.0
1.8
0.5
VOUT
0.0
2.5
2.4
VIN
1.8
1.5
1.0
VOUT
1.7
1.7
0.5
1.6
1.6
0.0
1.5
Time (100µs/div)
Time (100µs/div)
Line Regulation
Load Regulation
(VOUT = 1.2V)
(VOUT = 1.2V)
2.0
2.0
1.5
1.5
1.0
10mA
1mA
0.5
0.0
50mA
-0.5
150mA
100mA
-1.0
Output Error (%)
Output Error (%)
Output Voltage
(bottom) (V)
4.0
Input Voltage
(top) (V)
Line Transient
(VOUT = 1.8V; IOUT = 150mA; VIN = 3.6V to 4.2V)
Output Voltage
(bottom) (V)
Line Transient
(VOUT = 1.8V; IOUT = 100mA; VIN = 3.6V to 4.2V)
1.0
VIN = 2.7V
0.5
VIN = 3.6V
0.0
-0.5
VIN = 5.5V
-1.0
VIN = 4.2V
-1.5
-1.5
-2.0
-2.0
2.7
3.1
3.5
3.9
4.3
4.7
5.1
5.5
Input Voltage (V)
0
1
10
100
1000
Output Current (mA)
Load Regulation
(VOUT = 2.8V)
2.0
Output Error (%)
1.5
1.0
VIN = 3.3V
0.5
VIN = 3.6V
0.0
-0.5
VIN = 5.5V
-1.0
VIN = 4.2V
-1.5
-2.0
0
1
10
100
1000
Output Current (mA)
2503.2008.02.1.4
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11
PRODUCT DATASHEET
AAT2503178
SystemPowerTM
Adjustable 3-Channel Regulator
Functional Block Diagram
FB
Voltage
Reference
VIN
DH
Err.
Amp.
MODE/SYNC
EN
VP
LX
Logic
Control
Logic
DL
PGND
OUTA
VLDOA
ENB
Err.
Amp.
VLDOB
ENA
Err.
Amp.
Voltage
Reference
FBA
90%
VREF
POK
OUTB
FBB
AGND
Functional Description
Switch-Mode Step-Down Converter
The AAT2503 is a high performance power management
IC comprised of a step-down converter and two linear
regulators. The step-down converter operates in both
fixed and variable frequency modes for high efficiency
performance. The switching frequency is 2MHz, minimizing the size of the inductor. The converter requires only
three external components (CIN, COUT, and L). The LDOs
can deliver up to 150mA each. Each regulator has independent input voltage and enable pins and operates with
ceramic capacitors.
The switching regulator is a monolithic step-down converter operating with input voltage range of 2.7V to 5.5V.
Power devices are sized for 800mA current capability and
achieve over 95% efficiency. PFM operation maintains
high efficiency under light load conditions (typically
<50mA). The MODE/SYNC pin allows an optional “PWM
Only” mode. This maintains constant frequency and low
output ripple across all load conditions. Alternatively, the
IC can be synchronized to an external clock via the
MODE/SYNC input. External synchronization is main-
12
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2503.2008.02.1.4
PRODUCT DATASHEET
AAT2503178
SystemPowerTM
Adjustable 3-Channel Regulator
tained between 1MHz and 3MHz. It consumes 30μA of
typical no load quiescent current, making it also ideal for
light load applications. The oscillator operates at 2MHz,
minimizing the cost and size of external components.
A logic low on the EN pin shuts the converter down and
makes it consume less than 1μA of current.
Soft start increases the inductor current limit point in
discrete steps when the input voltage or enable input is
applied. It limits the current surge seen at the input and
eliminates output voltage overshoot.
Soft Start / Enable
Soft start limits the current surge seen at the input and
eliminates output voltage overshoot in the step-down
converter.
The step-down converter and the two LDOs have independent enable pins. When pulled low, the enable input
forces the LDO into shutdown mode and forces the stepdown converter into a low-power, non-switching state.
The input current during shutdown is less than 1μA.
For overload conditions, the peak input current is limited. As load impedance decreases and the output voltage
falls closer to zero, more power gets internally dissipated, raising the device temperature. Thermal protection
completely disables switching when internal dissipation
becomes excessive, protecting the device from damage.
The junction over-temperature threshold is 140°C with
15°C of hysteresis.
Linear Regulators
Control Loop
LDOA features an integrated Power-OK comparator
which indicates when the output is out of regulation. The
POK is an open drain output and it is held low when the
AAT2503 is in shutdown mode.
The AAT2503 includes a peak current mode step-down
converter. The current through the P-channel MOSFET
(high side) is sensed for current loop control, as well as
short-circuit and overload protection. A fixed slope compensation signal is added to the sensed current to maintain stability for duty cycles greater than 50%. The peak
current mode loop appears as a voltage-programmed
current source in parallel with the output capacitor.
The output of the voltage error amplifier programs the
current mode loop for the necessary peak switch current
to force a constant output voltage for all load and line
conditions. Internal loop compensation terminates the
transconductance voltage error amplifier output. For
fixed voltage versions, the error amplifier reference voltage is internally set to program the converter output
voltage. For the adjustable output, the error amplifier
reference is fixed at 0.9V.
2503.2008.02.1.4
The two linear regulators are high performance LDOs
where each LDO can source up to 150mA of current. For
added flexibility, both regulators have independent input
voltages operating from 2.8V to 5.5V. An external feedback pin for each LDO allows programming the output
voltage from VIN to 0.6V. The regulators have thermal
protection in case of adverse operating conditions.
Under-Voltage Lockout
Internal bias of all circuits is controlled via the VIN pin.
Under-voltage lockout guarantees sufficient VIN bias and
proper operation of all internal circuits prior to activation.
Over-Temperature Protection
Thermal protection completely disables switching when
internal dissipation becomes excessive. The junction
over-temperature threshold is 140°C with 15°C of hysteresis. Once an over-temperature or over-current fault
conditions is removed, the output voltage automatically
recovers.
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13
PRODUCT DATASHEET
AAT2503178
SystemPowerTM
Adjustable 3-Channel Regulator
Applications Information
CIN =
Step-Down Converter 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 AAT2503 stepdown converter is 0.51A/μsec. This equates to a slope
compensation that is 75% of the inductor current down
slope for a 1.5V output and 2.2μH inductor.
m=
0.75 ⋅ VO 0.75 ⋅ 1.5V
A
=
= 0.51
L
2.2μH
μsec
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 2.2μH CDRH2D14 series Sumida inductor has a
94mΩ DCR and a 1.5A DC current rating. At full 800mA
load, the inductor DC loss is 17mW which gives a 2.8%
loss in efficiency for a 800mA, 1.8V output.
Configuration
Output Voltage
Inductor
0.9V Adjustable
With External
Feedback
1V, 1.2V
1.5V, 1.8V
2.5V, 3.3V
1.5μH
2.2μH
3.3μH
Table 1: Inductor Values.
Input Capacitor
Select a 4.7μF to 10μF X7R or X5R ceramic capacitor for
the input of the step-down converter. 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.
14
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
⎠
Always examine the ceramic capacitor DC voltage coefficient characteristics when selecting the proper value.
For example, the capacitance of a 10μF, 6.3V, X5R ceramic capacitor with 5.0V DC applied is actually about 6μF.
The maximum input capacitor RMS current is:
IRMS = IO ·
VO ⎛
V ⎞
· 1- O
VIN ⎝
VIN ⎠
The input capacitor RMS ripple current varies with the
input and output voltage and will always be less than or
equal to half of the total DC load current.
VO ⎛
V ⎞
· 1- O =
VIN ⎝
VIN ⎠
D · (1 - D) =
0.52 =
1
2
for VIN = 2 · VO:
IRMS(MAX) =
VO
IO
2
⎛
V ⎞
· 1- O
The term V ⎝ V ⎠ 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.
IN
IN
The input capacitor provides a low impedance loop for
the edges of pulsed current drawn by the AAT2503. 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.
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2503.2008.02.1.4
PRODUCT DATASHEET
AAT2503178
SystemPowerTM
Adjustable 3-Channel Regulator
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.
tion establishes a limit on the minimum value for the
output capacitor with respect to load transients.
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.
Adjustable Output Resistor Selection
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 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 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.
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 equa-
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 output voltage on the step-down converter is programmed with external resistors R2 and R6. To limit the
bias current required for the external feedback resistor
string while maintaining good noise immunity, the minimum suggested value for R6 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
2 summarizes the resistor values for various output voltages with R6 set to either 59kΩ for good noise immunity or 221kΩ for reduced no load input current.
With enhanced transient response for extreme pulsed
load application, an external feed-forward capacitor (C1
in Fig.3) can be added.
VOUT (V)
R6 = 59kΩ
R2 (kΩ)
R6 = 221kΩ
R2 (kΩ)
0.9*
1.0
1.1
1.2
1.3
1.4
1.5
1.8
1.85
2.0
2.5
2.8
3.0
3.3
0
6.65
13.3
19.6
26.1
32.4
39.2
59.0
61.9
71.5
105
124
137
158
0
24.3
48.7
73.2
97.6
124
147
221
232
274
392
464
511
590
Table 2: Step-Down Converter Resistor Values for
Various Output Voltages.
* For the 0.9V output, R6 is open.
2503.2008.02.1.4
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15
PRODUCT DATASHEET
AAT2503178
SystemPowerTM
Adjustable 3-Channel Regulator
Thermal Calculations
There are three types of losses associated with the
AAT2503 step-down converter: switching losses, conduction losses, and quiescent current losses. Conduction
losses are associated with the RDS(ON) characteristics of
the power output switching devices. Switching losses are
dominated by the gate charge of the power output
switching devices. At full load, assuming continuous conduction mode (CCM), a simplified form of the LDO losses
is given by:
PTOTAL =
IO2 · (RDSON(HS) · VO + RDSON(LS) · [VIN - VO])
VIN
+ (tsw · F · 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(HS) + 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 θJA for the QFN34-20 package which is 50°C/W.
TJ(MAX) = PTOTAL · ΘJA + TAMB
LDO Linear Regulator Input Capacitor
A 1μF or larger capacitor is typically recommended for
CIN in most applications. A CIN capacitor is not required
for basic LDO regulator operation; however, if the
AAT2503 is physically located more than three centimeters from an input power source, a CIN capacitor will be
needed for stable operation. CIN should be located as
closely to the device VIN pin as practically possible. CIN
values greater than 1μF 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 CIN. There is no specific capacitor
16
ESR requirement for CIN; however, for 150mA 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.
Output Capacitor
For proper load voltage regulation and operational stability, a capacitor is required between pins OUTA, OUTB,
and GND. The COUT capacitor connection to the LDO
regulator ground pin should be made as direct as practically possible for maximum device performance. The
AAT2503 has been specifically designed to function with
very low ESR ceramic capacitors. For best performance,
ceramic capacitors are recommended.
Typical output capacitor values for maximum output current conditions range from 1μF to 10μF.
Applications utilizing the exceptionally low output noise
and optimum power supply ripple rejection characteristics of the AAT2503 should use 2.2μF or greater for COUT.
If desired, COUT may be increased without limit. In low
output current applications where output load is less
than 10mA, the minimum value for COUT can be as low as
0.47μF.
Capacitor Characteristics
Ceramic composition capacitors are highly recommended
over all other types of capacitors for use with the
AAT2503. Ceramic capacitors offer many advantages
over their tantalum and aluminum electrolytic counterparts. A ceramic capacitor typically has very low ESR, is
lower cost, has a smaller PCB footprint, and is nonpolarized. Line and load transient response of the LDO
regulator is improved by using low ESR ceramic capacitors. Since ceramic capacitors are non-polarized, they
are not prone to incorrect connection damage.
Equivalent Series Resistance
ESR is a very important characteristic to consider when
selecting a capacitor. ESR is the internal series resistance
associated with a capacitor that includes lead resistance,
internal connections, size and area, material composition, and ambient temperature. Typically, capacitor ESR
is measured in milliohms for ceramic capacitors and can
range to more than several ohms for tantalum or aluminum electrolytic capacitors.
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2503.2008.02.1.4
PRODUCT DATASHEET
AAT2503178
SystemPowerTM
Adjustable 3-Channel Regulator
Ceramic Capacitor Materials
POK Output
Ceramic capacitors less than 0.1μF are typically made
from NPO or C0G materials. NPO and C0G materials generally have tight tolerance and are very stable over temperature. Larger capacitor values are usually composed
of X7R, X5R, Z5U, or Y5V dielectric materials. These two
material types are not recommended for use with LDO
regulators since the capacitor tolerance can vary more
than ±50% over the operating temperature range of the
device. A 2.2μF Y5V capacitor could be reduced to 1μF
over temperature; this could cause problems for circuit
operation. X7R and X5R dielectrics are much more desirable. The temperature tolerance of X7R dielectric is better
than ±15%. Capacitor area is another contributor to
ESR. Capacitors which are physically large in size will
have a lower ESR when compared to a smaller sized
capacitor of an equivalent material and capacitance value.
These larger devices can improve circuit transient response
when compared to an equal value capacitor in a smaller
package size. Consult capacitor vendor datasheets carefully when selecting capacitors for LDO regulators.
LDOA of the AAT2503 features an integrated Power OK
comparator which can be used as an error flag. The POK
open drain output goes low when output voltage is 10%
(typ) below its nominal regulation voltage. Additionally,
any time LDOA is in shutdown, the POK output is pulled
low. Connect a pull-up resistor from POK to OUTA.
Adjustable Output Resistor Selection
The output voltage on the linear regulator is programmed
with external resistors: R4 and R7 for LDOA and R5 and
R8 for LDOB. Table 3 summarizes the resistor values for
various output voltages with R4 and R5 set to either
59kΩ for good noise immunity or 221kΩ for reduced no
load input current.
LDO VOUT
(V)
R7, R8 = 59kΩ
R4, R5 (kΩ)
R7, R8 = 221kΩ
R4, R5 (kΩ)
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
Table 3: LDO Linear Regulators Resistor Values
for Various Output Voltages.
Enable Function
The AAT2503 features an LDO regulator enable/disable
function. Each LDO has its own dedicated enable pin.
These pins (ENA, ENB) are active high and are compatible
with CMOS logic. To assure the LDO regulators will switch
on, ENA/B must be greater than 1.4V. The LDO regulators
will shut down when the voltage on the ENA/B pins falls
below 0.6V. In shutdown, the LDO regulators will consume less than 1.0μA of current. If the enable function is
not needed in a specific application, it may be tied to VIN
to keep the LDO regulator in a continuously on state.
Thermal Protection
Each of the two LDOs of the AAT2503 has an internal thermal protection circuit which will turn on when the device
die temperature exceeds 140°C. The LDO regulator outputs will remain in a shutdown state until the internal die
temperature falls back below the ~125°C trip point.
No-Load Stability
The LDOs in the AAT2503 are designed to maintain output voltage regulation and stability under operational
no-load conditions. This is an important characteristic for
applications where the output current may drop to zero.
Reverse Output-to-Input
Voltage Conditions and Protection
Under normal operating conditions, a parasitic diode
exists between the output and input of the LDO regulator. The input voltage should always remain greater than
the output load voltage maintaining a reverse bias on
the internal parasitic diode. Conditions where VOUT might
exceed VIN should be avoided since this would forward
bias the internal parasitic diode and allow excessive current flow into the VOUT pin, possibly damaging the LDO
regulator. In applications where there is a possibility of
* For the 0.6V output, R7 and R8 are open.
2503.2008.02.1.4
www.analogictech.com
17
PRODUCT DATASHEET
AAT2503178
SystemPowerTM
Adjustable 3-Channel Regulator
VOUT exceeding VIN for brief amounts of time during normal operation, the use of a larger value CIN capacitor is
highly recommended. A larger value of CIN with respect
to COUT will effect a slower CIN decay rate during shutdown, thus preventing VOUT from exceeding VIN. In applications where there is a greater danger of VOUT exceeding
VIN for extended periods of time, it is recommended to
place a Schottky diode across VIN to VOUT (connecting the
cathode to VIN and anode to VOUT). The Schottky diode
forward voltage should be less than 0.45V.
The maximum continuous output current for the AAT2503
is a function of the package power dissipation and the
input-to-output voltage drop across the LDO regulator.
To determine the maximum output current for a given
output voltage, refer to the following equation. This
calculation accounts for the total power dissipation of the
LDO regulator, including that caused by ground current.
PD(MAX) = [(VIN - VOUTA)IOUTA + (VIN · IGND)] + [(VIN - VOUTB)IOUTB + (VIN · IGND)]
Layout
Thermal Considerations and
High Output Current Applications
The LDOs of the AAT2503 are designed to deliver continuous output load currents of 150mA each under normal operation. This is desirable for circuit applications
where there might be a brief high in-rush current during
a power-on event.
The limiting characteristic for the maximum output load
current safe operating area is essentially package power
dissipation and the internal preset thermal limit of the
device. In order to obtain high operating currents, careful device layout and circuit operating conditions need to
be taken into account.
The suggested PCB layout for the AAT2503 is shown in
Figures 2 and 3. The following guidelines should be used
to help ensure a proper layout.
1.
2.
3.
The following discussions will assume the LDO regulator is
mounted on a printed circuit board utilizing the minimum
recommended footprint as stated in the layout considerations section of this document. At any given ambient
temperature (TA), the maximum package power dissipation can be determined by the following equation:
PD(MAX) =
4.
TJ(MAX) - TA
θJA
Constants for the AAT2503 are TJ(MAX) (the maximum
junction temperature for the device, which is 125°C) and
θJA = 50°C/W (the package thermal resistance). Typically,
maximum conditions are calculated at the maximum
operating temperature of TA = 85°C and under normal
ambient conditions where TA = 25°C. Given TA = 85°C,
the maximum package power dissipation is 800mW. At TA
= 25°C, the maximum package power dissipation is 2W.
18
5.
The input capacitors (C4, C7, C8, and C9) should
connect as closely as possible to VIN and PGND.
The output capacitor (C5, and C6) of the LDOs connect as closely as possible to OUT. C2 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 a narrow trace.
The trace should be kept wide, direct, and short.
The feedback trace 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 VOUT to
minimize the length of the high impedance feedback
trace. If possible, they should also be placed away
from the LX (switching node) and inductor to improve
noise immunity.
The resistance of the trace from the load return to
the PGND should be kept to a minimum. This will
help to minimize any error in DC regulation due to
differences in the potential of the internal signal
ground and the power ground.
Ensure all ground pins are tied to the ground plane.
No pins should be left floating. For maximum power
dissipation, it is recommended that the exposed pad
must be soldered to a good conductive PCB ground
plane layer to further increase local heat dissipation.
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2503.2008.02.1.4
PRODUCT DATASHEET
AAT2503178
SystemPowerTM
Adjustable 3-Channel Regulator
Figure 1: AAT2503 Evaluation Board
Component Side Layout.
Figure 2: AAT2503 Evaluation Board
Solder Side Layout.
SYNC
U1
R10
100k
5
AAT2503
FB
LX
9
LX
L1
4
VIN
SYNC
LX
2.2μH CDRH2D14
R1
13
VIN
OUTA
17
100
3
2
1
C4
0.1μF
18
3
2
1
VINB
19
C9
1μF
1
2
3
1
2
3
3
1
2
3
ENA
GND
POK
VINB
FBA
15
2
R12
100k
16
R2
C1
100pF
C3
0.01μF
R4
OUTA
10
14
ENB
VINA
C2
10μF
R3
100k
C8
1μF
VINA
EN
VOUT_BUCK
8
VP
EN/SET
ENB
ENA
OUTB
FBB
PGND
AGND
20
OUTB
R5
1
7
6
R7
59.0k
C7
10μF
R8
59.0k
C6
2.2μF
C5
2.2μF
R6
59.0k
GND
GND
POK
GND
C5, C6 2.2μF, 10V, X5R, 0603 GRM188R61A225KE34
C8, C9 1μF, 6.3V, X5R, 0603 GRM185R60J105KE26
C2, C7 10μF, 6.3V, X5R, 0805 GRM219R60J106KE19
L1 Sumida CDRH2D14 or Coltronics SD3814
U1 AAT2503 QFN34-20
Figure 3: AAT2503 Evaluation Board Schematic.
2503.2008.02.1.4
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19
PRODUCT DATASHEET
AAT2503178
SystemPowerTM
Adjustable 3-Channel Regulator
Manufacturer
Part Number
Value (μF)
Voltage Rating
Temp. Co.
Case Size
Murata
Murata
Murata
Murata
Murata
GRM219R60J106KE19
GRM188R60J475KE19
GRM188R61A225KE34
GRM188R61A105KA61
GRM185R60J105KE26
10
4.7
2.2
1.0
1.0
6.3
6.3
10
10
6.3
X5R
X5R
X5R
X5R
X5R
0805
0603
0603
0603
0603
Table 4: Surface Mount Capacitors.
Manufacturer
Part Number
Inductance (μH)
Saturated
Rated Current
(mA)
Sumida
Sumida
Sumida
Coiltronics
Coiltronics
Coiltronics
Taiyo Yuden
Taiyo Yuden
Taiyo Yuden
CDRH2D14-1R5
CDRH2D14-2R2
CDRH2D14-3R3
SD3812-1R5
SD3812-2R2
SD3812-3R3
NR3010-1R5
NR3010-2R2
NR3010-3R3
1.5
2.2
3.3
1.5
2.2
3.3
1.5
2.2
3.3
1800
1500
1200
1580
1320
1100
1200
1100
870
DCR (mΩ)
Size (mm)
LxWxH
Type
63
94
125
78
111
159
80
95
140
3.2x3.2x1.55
3.2x3.2x1.55
3.2x3.2x1.55
4.0x4.0x1.2
4.0x4.0x1.2
4.0x4.0x1.2
3.0x3.0x1.0
3.0x3.0x1.0
3.0x3.0x1.0
Shielded
Shielded
Shielded
Shielded
Shielded
Shielded
Shielded
Shielded
Shielded
Table 5: Suggested Inductors and Suppliers.
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2503.2008.02.1.4
PRODUCT DATASHEET
AAT2503178
SystemPowerTM
Adjustable 3-Channel Regulator
Ordering Information
Voltage
Package
Channel 1
Channel 2
Channel 3
Marking1
Part Number (Tape and Reel)2
QFN34-20
0.9V
0.6V
0.6V
TPXYY
AAT2503IZL-BAA-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.
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.
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PRODUCT DATASHEET
AAT2503178
SystemPowerTM
Adjustable 3-Channel Regulator
Package Information1
QFN34-20
Detail "A"
Index Area
(D/2 x E/2)
Detail "B"
4.00 ± 0.05
0.925 ± 0.125
7.5° ± 7.5°
0.025 ± 0.025
0.214 ± 0.036
Side View
3.00 ± 0.05
Top View
Bottom View
0.40 ± 0.10
0.075 ± 0.075
Option B:
R0.30 (4x) max
Round corner
0.50 ± 0.05
Option A:
C0.30 (4x) max
Chamfered corner
0.24 ± 0.06
Pin 1 indicator
(optional)
Detail "A"
Detail "B"
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.
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 specifications 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 fitness 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. Specific testing of all parameters of each device is not necessarily performed. AnalogicTech and the AnalogicTech logo are trademarks of Advanced Analogic Technologies Incorporated. All other
brand and product names appearing in this document are registered trademarks or trademarks of their respective holders.
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