The AAT2504 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.
The two LDOs have an input voltage range of 1.8V to
5.5V, making them well-suited for post regulating from
the step-down converter.
The step-down converter optimizes power efficiency
throughout the load range. Pulling the MODE/SYNC pin
high enables “PWM Only” operation, maintaining con-
stant frequency and low output ripple across the operat-
ing range. Alternatively, the converter may be synchro-
nized to an external clock to the MODE/ SYNC pin. The
step-down converter delivers up to 800mA of output cur-
rent. 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 300mA 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.
Typical no load quiescent current is a low 80μA when the
step-down converter and LDOs are enabled.
The AAT2504 is available in a Pb-free 3x4mm QFN34-20
package and is rated over the -40°C to +85°C tempera-
ture range.
Adjustable 3-Channel Regulator
Features
• 800mA Buck Converter
▪
V
IN
Range: 2.7V to 5.5V
▪
V
OUT
Range: 0.9V to V
IN
, Adjustable
▪
High Efficiency: 95%
▪
2MHz Switching Frequency
▪
Synchronizable to External Clock
▪
Internal Soft Start
• Two 300mA Linear Regulators
▪
LDO Input Voltage Range: 1.62V to 5.5V
▪
Low Dropout Voltage
▪
High Output Accuracy: ±1.5%
• Low Total Quiescent Current I
Q
(80μA)
• Independent Enable Pins
• Over-Temperature Protection
• QFN34-20 Package
• -40°C to +85°C Temperature Range
Applications
•
•
•
•
•
Cellular Phones
Digital Cameras
Handheld Instruments
Microprocessor/DSP Core/IO Power
PDAs and Handheld Computers
Typical Application
L
LX
AAT2504
V
IN
VIN
VLDOA
VLDOB
VP
MODE/SYNC
ENA
ENB
EN
V
OUT
(Step-down)
FB
OUTA
100kΩ
POK
FBA
OUTB
OUTB
POK
R
1
R
1A
OUTA
C
OUT
R
1B
FBB
R
2A
2.2μF
2.2μF
R
2
R
2B
PGND
AGND
2504.2008.02.1.2
www.analogictech.com
1
PRODUCT DATASHEET
AAT250417
SystemPower
TM
Pin Descriptions
Pin #
1
2
3
4
Adjustable 3-Channel Regulator
Symbol
FBB
ENA
ENB
MODE/SYNC
Function
Feedback input pin for LDOB. This pin is used to regulate the output of LDOB to the desired value via an
external resistor divider.
Enable pin for LDOA. Active high.
Enable pin for LDOB. Active high.
PWM operation and oscillator synchronization pin. Connect to ground for PWM/Light Load operation
and optimized efficiency throughout the load range. Connect high for low noise PWM operation under
all operating conditions. When connected to an external clock, the internal oscillator is disabled and the
step-down converter is synchronized to an external clock applied to this pin (PWM only).
Feedback input pin for the step-down converter. This pin 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
fi
lter with de-
coupling to AGND.
Enable for the step-down converter. Active high.
Power-OK pin with open drain output. It is pulled low when the OUTA pin is outside the regulation win-
dow. Place a pull-up resistor between POK and OUTA.
Feedback input pin for LDOA. This pin is used to regulate the output of LDOA to the desired value via an
external resistor divider.
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.
5
6
7
8, 9
10
11, 12
13
14
15
16
17
18
19
20
EP
FB
AGND
PGND
LX
VP
N/C
VIN
EN
POK
FBA
OUTA
VLDOA
VLDOB
OUTB
Pin Configuration
QFN34-20
(Top View)
OUTA
VLDOA
VLDOB
OUTB
20
19
18
17
FBB
ENA
ENB
MODE/SYNC
FB
AGND
1
2
3
4
5
6
10
9
7
8
16
15
14
13
12
11
FBA
POK
EN
VIN
N/C
N/C
2
www.analogictech.com
VP
LX
LX
PGND
2504.2008.02.1.2
PRODUCT DATASHEET
AAT250417
SystemPower
TM
Absolute Maximum Ratings
1
Symbol
V
P
, V
IN
, V
LDO
V
LX
V
FB
V
EN
T
J
T
LEAD
Adjustable 3-Channel Regulator
Description
Input Voltage and Bias Power to GND
LX to GND
FB to GND
EN and EN_LDO to GND
Operating Junction Temperature Range
Maximum Soldering Temperature (at leads, 10 sec)
Value
6.0
-0.3 to V
P
+ 0.3
-0.3 to V
P
+ 0.3
-0.3 to 6.0
-40 to 150
300
Units
V
V
V
V
°C
°C
Thermal Information
Symbol
P
D
θ
JA
Description
Maximum Power Dissipation (T
A
= 25°C)
Thermal Resistance
2
Value
2.0
50
Units
W
°C/W
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.
2504.2008.02.1.2
www.analogictech.com
3
PRODUCT DATASHEET
AAT250417
SystemPower
TM
Electrical Characteristics
1
V
IN
= 3.6V; T
A
= -40°C to +85°C, unless otherwise noted. Typical values are T
A
= 25°C.
Symbol
Description
Conditions
ENA = ENB = EN = V
IN
; I
LOAD
= 0
ENA = ENB = EN = GND
V
IN
Rising
Hysteresis
V
IN
Falling
Adjustable 3-Channel Regulator
Min
Typ
80
Max
145
1.0
2.2
Units
μA
μA
V
mV
V
V
%
V
mV
%/V
V
V
mA
μA
°C
°C
% of V
OUT
% of V
OUT
V
μA
V
%
V
V
μA
μA
μA
A
mΩ
mΩ
%
%/V
MHz
°C
°C
V
V
μA
Bias Power Supply
I
Q
Quiescent Current
I
SHDN
Shutdown Current
UVLO
Under-Voltage Lockout Voltage
250
1.7
1.62
-1.5
-2.5
0.593
5.5
1.5
2.5
0.607
300
0.09
0.6
LDOA, LDOB
V
LDO
Input Voltage
V
OUT
V
FB
V
DO
Output Voltage Tolerance
Feedback Voltage
Dropout Voltage
2, 3
Line Regulation
4
Enable Threshold Low
Enable Threshold High
Output Current
Shutdown Current
Over-Temperature Shutdown Threshold
Over-Temperature Shutdown Hysteresis
I
OUT
= 1mA
to 300mA
T
A
= 25°C
T
A
= -40°C to +85°C
0.6
ΔV
LINEREG
/V
IN
V
EN(L)
V
EN(H)
I
OUT
I
SHT
T
SD
T
HYS
LDOA
Power-OK Trip Threshold
V
POK
V
POKHYS
Power-OK Hysteresis
V
POK(LO)
Power-OK Output Voltage Low
I
POK
Power-OK Output Leakage Current
Step-Down Converter
V
IN
Input Voltage
V
OUT
Output Voltage Tolerance
V
OUT
Programmable Range
V
OUT
V
FB
Feedback Threshold Voltage
I
SHDN
Shutdown Current
I
LX_LEAK
LX Leakage Current
I
FB
Feedback Leakage
I
LIM
Current Limit
R
DS(ON)H
High Side Switch On Resistance
R
DS(ON)L
Low Side Switch On Resistance
ΔV
LOADREG
/V
OUT
Load Regulation
ΔV
LINEREG
/V
IN
Line Regulation
Oscillator Frequency
F
OSC
T
SD
Over-Temperature Shutdown Threshold
Over-Temperature Shutdown Hysteresis
T
HYS
V
EN(L)
Enable Threshold Low
Enable Threshold High
V
EN(H)
I
EN
EN Input Leakage
I
OUT
= 300mA
V
IN
= V
OUT
+ 1 to 5.0V
1.4
300
V
LDO (MIN)
= 2.5
V
IN
= 5V
1.0
140
15
V
OUT
Rising, T
A
= 25°C
I
SINK
= 1mA
V
POK
<5.5V, V
OUT
in Regulation
80
90
1.0
98
0.4
1.0
I
OUT
= 0 to 800mA; V
IN
= 2.7V to 5.5V
2.7
-3.0
0.9
0.891
0.9
EN = GND
V
IN
= 5.5, V
LX
= 0 - V
IN
V
FB
= 1.0V
280
160
0.2
0.2
2.0
140
15
5.5
3.0
V
IN
0.909
1.0
1.0
0.2
1.2
I
LOAD
= 10 to 800mA
1.6
2.4
0.6
V
EN
= 5V, V
IN
= 5V
1.4
-1.0
1.0
1. The AAT2504 is guaranteed to meet performance specifications over the -40°C to +85°C operating temperature range and is assured by design, characterization, and correla-
京公网安备 11010802033920号
EEWORLD
