AAT2503
Adjustable 3-Channel Regulator
Pin Descriptions
Pin #
Symbol
Function
1
FBB
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.
2
3
4
ENA
ENB
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.
MODE/SYNC 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).
5
FB
Feedback input pin for the step-down converter. This pin is connected to the converter out-
put 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.
6
7
AGND
PGND
Ground connection pin.
Main power ground return pin for the step-down converter. Connect to the output and input
capacitor return.
8, 9
LX
Connect inductor to this pin. Switching node internally connected to the drain of both high-
and low-side MOSFETs.
10
11, 12
13
VP
N/C
VIN
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.
14
15
16
EN
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.
POK
FBA
Power-OK pin with open drain output. It is pulled low when the OUTA pin is outside the regu-
lation window of 10ꢀ. 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.
17
18
19
20
EP
OUTA
VLDOA
VLDOB
OUTB
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.
2
2503.2007.04.1.1
ANALOGICTECH [ ADVANCED ANALOGIC TECHNOLOGIES ]
