RT8802A datasheet(3/28 Pages) RICHTEK

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RT8802A

DS8802A-04 August 2007

www.richtek.com

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Functional Pin Description

VTT/EN (Pin 1)

The pin is defined as the chip enable, and the VTT is

applied for internal VID pull high power and power sequence

monitoring.

VR_Ready (Pin 2)

Power good open-drain output.

FBRTN (Pin 3)

Feedback return pin. VIDDAC and error amplifier reference

for remote sensing of the output voltage.

FB (Pin 4)

Inverting input pin of the internal error amplifier.

COMP (Pin 5)

Output pin of the error amplifier and input pin of the PWM

comparator.

SS (Pin 6)

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

soft-start time interval.

QRSEL (Pin 7)

Quick response mode select pin. When QRSEL = GND

and quick response is triggered during heavy load to light

load transient, 2 channels will turn on simultaneously to

prevent VOUT undershoot. When QRSEL = NC and quick

response is triggered, all channels will turn on

simultaneously to prevent VOUT undershoot.

VR_FAN (Pin 8)

The pin is defined to signal VR thermal information for

external VR thermal dissipation scheme triggering.

VR_HOT (Pin 9)

The pin is defined to signal VR thermal information for

external VR thermal dissipation scheme triggering.

TSEN (Pin 10)

Temperature detect pin for VR_HOT and VR_FAN.

IOUT (Pin 11)

Output current indication pin. The current through IOUT

pin is proportional to the total output current.

DVD (Pin 12)

Programmable power UVLO detection input. Trip threshold

is 1V at VDVD rising.

RT (Pin 13)

The pin is defined to set internal switching operation

frequency. Connect this pin to GND with a resistor RRT to

set the frequency FSW.

OFS (Pin 14)

The pin is defined for load line offset setting.

ADJ (Pin 15)

Current sense output for active droop adjusting. Connect

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

TCOC (Pin 16)

Input pin for setting thermally compensated over current

trigger point. Voltage on the pin is compared with VADJ. If

VADJ > VTCOC then OCP is triggered.

IMAX (Pin 17)

The pin is defined to set threshold of over current.

ISN1 (Pin 18)

Current sense negative input pin for channel 1 current

sensing.

ISN24 (Pin 19)

Current sense negative input pins for channel 2 and

channel 4 current sensing.

ISN35 (Pin 20)

Current sense negative input pins for channel 3 and

channel 5 current sensing.

3500

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