RT9243GS datasheet(3/18 Pages) RICHTEK

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RT9243

DS9243-07 March 2007

www.richtek.com

Functional Pin Description

OVP (Pin 1)

Over voltage trip output.

PGOOD (Pin 2)

Power good open-drain output.

VID4 (Pin 3), VID3 (Pin 4), VID2 (Pin 5), VID1 (Pin 6),

VID0 (Pin 7) & VID125 (Pin 8)

DAC voltage identification inputs for VRD10.x. These pins

are internally pulled to 3V if left open.

VOSS (Pin 9)

VCORE initial value offset. Connect this pin to GND with a

resistor to set the offset value.

ADJ (Pin 10)

Current sense output for active droop adjust. Connect a

resistor from this pin to GND to set the load droop.

SS (Pin 11)

Connect this SS pin to GND with a capacitor to set the

soft-start time interval. Pulling this pin below 1V (ramp

valley of sawtooth wave in pulse width modulator) would

make all PWMs low, turn on low side MOSFETs and turn

off high side MOSFETs.

FB (Pin 12)

Inverting input of the internal error amplifier.

COMP (Pin 13)

Output of the error amplifier and input of the PWM

comparator.

VDIF (Pin 14)

VCORE differential sense output.

VSEN (Pin 19)

VCORE differential sense positive input.

SGND (Pin 20)

VCORE differential sense negative input.

GND (Pin 21)

Ground for the IC.

PWM1 (Pin 25), PWM2 (Pin 26), PWM3 (Pin 22) &

PWM4 (Pin 29)

PWM outputs for each driven channel. Connect these pins

to the PWM input of the MOSFET driver. For systems

which use 3 channels, connect PWM4 high. Two channel

systems connect PWM3 and PWM4 high.

ISN1 (Pin 18), ISN2 (Pin 17), ISN3 (Pin 16) & ISN4

(Pin 15)

RDS(ON) current sense inputs from each individual converter

channel sense component's GND node.

ISP1 (Pin 24), ISP2 (Pin 27), ISP3 (Pin 23) & ISP4

(Pin 28)

RDS(ON) current sense inputs for each individual converter

channel. Tie this pin to the component's sense node.

VCC (Pin 30)

IC power supply. Connect this pin to a 5V supply.

DVD (Pin 31)

Programmable power UVLO detection input. Trip threshold

= 2V at VDVD rising.

RT (Pin 32)

Switching frequency setting. Connect this pin to GND with

a resistor to set the frequency.

Ω)

Frequency vs. RRT

100

150

200

250

300

350

400

450

20304050

6070

RRT

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