RT9214 datasheet(2/17 Pages) RICHTEK

2 / 17 page

RT9214

www.richtek.com

DS9214-13

September 2007

Functional Pin Description

BOOT (Pin 1)

Bootstrap supply pin for the upper gate driver. Connect

the bootstrap capacitor between BOOT pin and the PHASE

pin. The bootstrap capacitor provides the charge to turn

on the upper MOSFET.

UGATE (Pin 2)

Upper gate driver output. Connect to the gate of high-

side power N-Channel MOSFET. This pin is monitored by

the adaptive shoot-through protection circuitry to

determine when the upper MOSFET has turned off.

GND (Pin 3)

Both signal and power ground for the IC. All voltage levels

are measured with respect to this pin. Ties the pin directly

to the low-side MOSFET source and ground plane with

the lowest impedance.

LGATE (Pin 4)

Lower gate drive output. Connect to the gate of low-side

power N-Channel MOSFET. This pin is monitored by the

adaptive shoot-through protection circuitry to determine

when the lower MOSFET has turned off.

VCC (Pin 5)

Connect this pin to a well-decoupled 5V or 12V bias

supply. It is also the positive supply for the lower gate

driver, LGATE.

FB (Pin 6)

Switcher feedback voltage. This pin is the inverting input

of the error amplifier. FB senses the switcher output

through an external resistor divider network.

OPS (OCSET, POR and Shut-Down) (Pin 7)

This pin provides multi-function of the over-current setting,

UGATE turn-on POR sensing, and shut-down features.

Connecting a resistor (ROCSET) between OPS and

PHASE pins sets the over-current trip point.

Pulling the pin to ground resets the device and all external

MOSFETs are turned off allowing the output voltage power

rails to float.

This pin is also used to detect VIN in power on stage and

issues an internal POR signal.

PHASE (Pin 8)

Connect this pin to the source of the upper MOSFET and

the drain of the lower MOSFET.

NC [Exposed Pad (9)]

No Internal Connection.

Typical Application Circuit

2%)

(0.8V

voltage

reference

Internal

)

REF

OUT

BOOT

VCC

PHASE

UGATE

OPS

LGATE

GND

1uF

3uH

+5V to +12V

OUT

0.1uF

470uF

1000uFx3

3904

0.1-0.33uF

1uF

200-1k

RT9214

+3.3V/+5V/+12V

1N4148

ROCSET

C6 to C8

Disable >

2.2

BOOT

UGATE

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