PRODUCT DATASHEET
AAT2158
SwitchReg
TM
Pin Descriptions
Pin #
1, 2, 3
4
5
6, 8, 16
7
9
10, 11, 12
13, 14, 15
EP
1.5A Low Noise Step-Down Converter
Symbol
PGND
FB
SGND
N/C
EN
VCC
VP
LX
Function
Main power ground return pin. Connect to the output and input capacitor return. (See board layout rules.)
Feedback input pin. For an adjustable output, connect an external resistive divider to this pin. For fixed
output voltage versions, FB is the output pin of the converter.
Signal ground. Connect the return of all small signal components to this pin. (See board layout rules.)
Not internally connected.
Enable input pin. A logic high enables the converter; a logic low forces the AAT1158 into shutdown mode
reducing the supply current to less than 1µA. The pin should not be left floating.
Bias supply. Supplies power for the internal circuitry. Connect to input power.
Input supply voltage for the converter power stage. Must be closely decoupled to PGND.
Connect inductor to these pins. Switching node internally connected to the drain of both high- and low-side
MOSFETs.
Exposed paddle (bottom); connect to PGND directly beneath package.
Pin Configuration
QFN33-16
(Top View)
LX
LX
LX
N/C
16
15
14
13
PGND
PGND
PGND
FB
1
2
3
4
5
6
7
8
12
11
10
9
VP
VP
VP
VCC
2
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N/C
EN
N/C
SGND
2158.2008.10.1.5
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