RT9209/A

4

DS9209/A-08 March 2007

www.richtek.com

Absolute Maximum Ratings

BOOT & UGATE to GND --------------------------------------------------------------------------------------------- 19V

Input, Output or I/O Voltage ----------------------------------------------------------------------------------------- GND-0.3V to 7V

SOP-8 -------------------------------------------------------------------------------------------------------------------- 0.625W

Package Thermal Resistance

SOP-8,

Ambient Temperature Range ---------------------------------------------------------------------------------------- 0° C to +70° C

Junction Temperature Range ---------------------------------------------------------------------------------------- 0

°C to +125°C

Storage Temperature Range ----------------------------------------------------------------------------------------

Lead Temperature (Soldering, 10 sec.) --------------------------------------------------------------------------- 260°C

CAUTION:

This is a stress only rating and operation of the device at these or any other conditions above those indicated in the

operational sections of this specification is not implied.

Functional Pin Description

FB (Pin1)

This pin is connected to the PWM converter's output divider.

This pin also connects to internal PWM error amplifier

inverting input and protection monitor.

VCC (Pin 2)

This is the main bias supply for the RT9209/A. This pin

also provides the gate bias charge for the lower MOSFETs

gate. The voltage at this pin monitored for power-on reset

(POR) purpose. This pin is also the internal 6.5V regulator

output powered from BOOT pin when BOOT pin is directly

powered from ATX 12V.

LGATE (Pin 3)

Connect LGATE to the PWM converter's lower MOSFET

gate. This pin provides the gate drive for the lower

MOSFET.

GND (Pin 4)

Signal and power ground for the IC. All voltage levels are

measured with respect to this pin.

UGATE (Pin 5)

Connect UGATE pin to the PWM converter's upper

MOSFET gate. This pin provides the gate drive for the

upper MOSFET.

BOOT (Pin 6)

This pin provides ground referenced bias voltage to the

upper MOSFET driver. A bootstrap circuit is used to create

a voltage suitable to drive a logic-level N-Channel

MOSFET when operating at a single 5V power supply.

This pin also could be powered from ATX 12V, in this

situation, a internal 6.5V regulator will supply to VCC pin

for internal voltage bias.

PGOOD (Pin 7)

PGOOD is an open collector output used to indicate the

status of the PWM converter output voltage. This pin is

pulled low when the FB is not over 90% of the reference

voltage.

SS (Pin 8)

Connect a capacitor from this pin to ground. This capacitor,

along with an internal 22

μA current source, sets the soft-

start internal of the synchronous PWM converter.