RT8805 查看數據表（PDF） - Richtek Technology

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RT8805

Two Phase General Purpose PWM Controller

Richtek Technology 

Preliminary

RT8805

Functional Pin Description

UGATE1 (Pin 1), UGATE2 (Pin 11)

Upper Gate Drive. These pins drive the gates of the highside

MOSFETs.

BOOT1 (Pin 2), BOOT2 (Pin 10)

Bootstrap Power Pin. These pins power the high-side

MOSFET drivers. Connect These pins to the junctions of

the bootstrap capacitors.

AGND (Pin 3)

Chip Analog Ground.

IMAX (Pin 4)

Maximum Current Setting. This pin sets the current limiting

level. Connect this pin with resistor to ground to set the

current limit.

PHASE1 (Pin 16), PHASE2 (Pin 12)

These pins are return nodes of the high-side driver.

Connect These pins to high-side MOSFET sources

together with the low-side MOSFET drains and the

inductors.

VCC (Pin 14)

The VCC pin is the external 12V power. Internal 5V power

(VDD) is regulated from this pin. This pin also powers the

low side MOSFETS drivers.

GND (Exposed Pad)

Exposed pad should be soldered to PCB board and

connected to GND.

RT (Pin 5)

Timing Resistor. Connect a resistor from RT to AGND to

set the clock frequency.

SS (Pin 6)

Soft-Start Pin. This pin provides soft-start function for

controller. The COMP voltage of the converter follows the

ramping voltage on the SS pin.

COMP (Pin 7)

Compensation Pin. This pin is output node of the error

amplifier.

FB (Pin 8)

Feedback Pin. This pin is negative input pin of the error

amplifier.

PGOOD (Pin 9)

Power Good. PGOOD is an open drain output used to

indicate the status of the voltages on SS pin and FB pin.

PGOOD will go high impedance when SS > 3.7V and FB

> 0.6V.

LGATE1 (Pin 15), LGATE2 (Pin 13)

Lower Gate Drive. These pins drive the gate of the lowside

MOSFETs.

DS8805-01 November 2005

www.richtek.com

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