RT9991

3

DS9991-01 April 2011

www.richtek.com

Pin No.

Pin Name

Pin Function

1, 18, 19, 22, 23, 32,

33 (Exposed Pad)

GND

Ground. The exposed pad must be soldered to a large PCB and connected

to GND for maximum power dissipation.

2, 3, 4

LX3

Buck Converter 3 Switch Output (inductor connection point).

5, 6

VIN3

Buck Converter 3 Power Supply Input.

7

EN3

Buck Converter 3 Chip Enable (Active High).

8

FB3

Buck Converter 3 Feedback Input.

9, 12, 29, 30, 31

NC

No Internal Connection.

10

RESET

Reset Output.

11

VDET

Threshold Voltage Detect Setting.

13

FB1

Buck Converter 1 Feedback Input.

14

EN1

Buck Converter 1 Chip Enable (Active High).

15, 20

VIN1

Buck Converter 1 Power Supply Input.

16, 17

LX1

Buck Converter 1 Switch Output (inductor connection point).

21, 26

VIN2

Buck Converter 2 Power Supply Input.

24, 25

LX2

Buck Converter 2 Switch Output (inductor connection point).

27

EN2

Buck Converter 2 Chip Enable (Active High).

28

FB2

Buck Converter 2 Feedback Input.

Functional Pin Description