RT9212

Preliminary

DS9212-05 March 2007

3

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Functional Pin Description

UGATE1 (Pin 1)

Channel 1 upper gate driver output. Connect to gate of the

high-side power N-MOSFET. This pin is monitored by the

adaptive shoot-through protection circuitry to determine

when the upper MOSFET has turned off.

BOOT1 (Pin 2)

Bootstrap supply pin for the upper gate driver. Connect

the bootstrap capacitor between BOOT1 pin and the

PHASE1 pin. The bootstrap capacitor provides the charge

to turn on the upper MOSFET.

PHASE1 (Pin 3)

Connect this pin to the source of the upper MOSFET and

the drain of the lower MOSFET. PHASE1 is used to

monitor the Voltage drop across the upper MOSFET of

the channel 1 regulator for over-current protection.

NC (Pin 4, 7, 8)

No connection. Don’ t connect any component to this pin.

FB1 (Pin 5)

Channel 1 feedback voltage. This pin is the inverting input

of the error amplifier. FB1 senses the channel 1 through

an external resistor divider network.

COMP1 (Pin 6)

Channel 1 external compensation. This pin internally

connects to the output of the error amplifier and input of

the PWM comparator. Use a RC + C network at this pin

to compensate the feedback loop to provide optimum

transient response.

GNDA (Pin 9)

Signal ground for the IC. All voltage levels are measured

with respect to this pin. Ties the pin directly to ground

plane with the lowest impedance.

PHASE2 (Pin 10)

Connect this pin to the source of the upper MOSFET and

the drain of the lower MOSFET. PHASE2 is used to

monitor the Voltage drop across the upper MOSFET of

the channel 2 regulator for over-current protection.

BOOT2 (Pin 11)

Bootstrap supply pin for the upper gate driver. Connect the

bootstrap capacitor between BOOT2 pin and the PHASE2

pin. The bootstrap capacitor provides the charge to turn on

the upper MOSFET.

UGATE2 (Pin 12)

Channel 2 upper gate driver output. Connect to gate of the

high-side power N-MOSFET. This pin is monitored by the

adaptive shoot-through protection circuitry to determine

when the upper MOSFET has turned off.

PGND2 (Pin 13)

Return pin for high currents flowing in low-side power

N-MOSFET. Ties the pin directly to the low-side MOSFET

source and ground plane with the lowest impedance.

LGATE2 (Pin 14)

Channel 2 lower gate drive output. Connect to gate of the

low-side power N-MOSFET. This pin is monitored by the

adaptive shoot-through protection circuitry to determine

when the lower MOSFET has turned off.

VCC (Pin 15)

Connect this pin to a well-decoupled 5V bias supply. It is

also the positive supply for the lower gate driver, LGATE2.

DRV (Pin 16)

Connect this pin to the base of an external transistor. This

pin provides the drive for the linear regulator's pass

transistor.

FBL (Pin 17)

Linear regulator feedback voltage. This pin is the inverting

input of the error amplifier and protection monitor. Connect

this pin to the external resistor divider network of the linear

regulator.

FB2 (Pin 18)

Channel 2 feedback voltage. This pin is the inverting input

of the error amplifier. FB2 senses the channel 2 through an

external resistor divider network.