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Axelite Confidential Materials, do not copy or distribute without written consent.

Rev.1.6 Nov.27, 2019

AX6639/A

VIN

VOUT

GND

CIN

VIN

COUT

AX6639-TO263-5L

10uF

10uF

VOUT

EN

ON

OFF

2

1

3

4

FB

R1

R2

5

VIN

VOUT

GND

CIN

VIN

AX6639-SOP-8L-EP

10uF

VOUT

FB

EN

ON

OFF

3

2

NC

1, 4, 5

7

6

R1

R2

8

COUT

10uF

VOVT = VFB × (1+R1/R2)

VFB = 0.8V

R2 Range = 50K ~ 300K



FUNCTION DESCRIPTIONS

A minimum of 10µF capacitor must be connected from VOUT to ground to insure

stability. Typically a large storage capacitor is connected from VIN to ground to ensure that

the input voltage does not sag below the minimum dropout voltage during the load transient

response. This pin must always be dropout voltage higher than VOUT in order for the device

to regulate properly.

Enable Function

The AX6639/A (TO263-5L and SOP-8L-EP only) features an LDO regulator

enable/disable function. To assure the LDO regulator will switch on; the EN turn on control

level must be greater than 2.0 volts. The LDO regulator will go into the shutdown mode when

the voltage on the EN pin falls below 0.6 volts. If the enable function is not needed in a

specific application, it can be floating.