RT9199

4

DS9199-07

September 2007

www.richtek.com

Functional Pin Description

VIN

input rail from dropping during large load transient, a large, low ESR capacitor is recommended to use. The capacitor

should be placed as close as possible to the VIN pin.

GND (Exposed Pad)

Common Ground. The exposed pad must be soldered to a large PCB and connected to GND for maximum power

dissipation.

VCNTL

VCNTL supplies the internal control circuitry and provides the drive voltage. The driving capability of output current is

μF capacitor

from this pin to GND. An important note is that VIN should be kept lower or equal to VCNTL.

REFEN

Reference voltage input and active low shutdown control pin. Two resistors dividing down the VIN voltage on the pin to

create the regulated output voltage. Pulling the pin to ground turns off the device by an open-drain, such as 2N7002,

signal N-MOSFET.

VOUT

Regulator output. VOUT is regulated to REFEN voltage that is used to terminate the bus resistors. It is capable of sinking

and sourcing current while regulating the output rail. To maintain adequate large signal transient response, typical value

of 1000

transients on VOUT.

Function Block Diagram

GND

VCNTL

REFEN

Current Limit

Thermal Protection

VOUT

EA

VIN