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http://www.union-ic.com Rev.02 Mar.2016

2/12

UM3429

Pin Configurations

Top View

VIN

SW

VOUT

GND

SHDN

FB

1

2

3

4

5

6

UCQ

1

2

3

4

5

6

M: Month Code

UM3429S

SOT23-6

(Top View)

9

5

6

7

8

4

3

2

1

VIN

VOUT

SHDN

GND

FB

NC

SW

GND

ABE

M: Month Code

UM3429DA

DFN8 2.0×2.0

Pin Description

Pin Number

Symbol

Description

UM3429S

UM3429DA

1

7

SW

these PCB trace lengths as short and wide as possible.

2

-

GND

Ground. Provide a short direct PCB path between GND

-

4, 8

3

5

FB

Feedback Input Pin. Connect to the center point of the

external resistor divider and set the output voltage by:

4

3

SHDN

____________

Logic Controlled Shutdown Input. Low logic active. In

shutdown mode, all functions are disabled drawing < μA

supply current. Do not leave SHDN

____________

floating.

5

2

VOUT

Output Voltage Sense Input and Drain of the Internal

Synchronous Rectifier P-MOSFET. Bias is derived from

filter capacitor(s) as short and wide as possible.

6

1

VIN

Battery Input Voltage. The device gets its start-up bias

Thus, once started, operation is completely independent

level and the battery’s internal series resistance

-

9

Exposed

Pad

The exposed pad must be soldered to the PCB ground

plane. It serves as an additional ground connection and as

a means of conducting heat away from the package.

-

6

NC

Not connected.