RT9644 データシートの表示（PDF） - Richtek Technology

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RT9644

ACPI Regulator/Controller for Dual Channel DDR Memory Systems

Richtek Technology 

RT9644/A

Preliminary

Pin No.

RT9644 RT9644A

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17

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19

Pin Name

Pin Function

COMP4

PWM4

The COMP4 pin provides the compensation AC network for the 2nd

synchronous DC-DC buck PWM controller.

The PWM4 pin is the output of the 2nd synchronous DC-DC buck converter

used for VGMCH. The PWM4 should be connected to suitable RICHTEK

MOSFET driver to drive 2 N-MOSFETs.

VDDQ synchronous DC-DC buck converter has over current protection via

the ROCSET to decide the over current criteria. Connect a resistor (ROCSET)

from this pin to the drain of the upper N-MOSFET. There is an internal 20 µA

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OCSET current sink (IOCSET) from the OCSET pin. We can define the OC trip point

via ROCSET, IOCSET, and the upper N-MOSFET on-resistance (RDS(ON)) as

following equation :

IPEAK = (IOCSET x ROCSET) / RDS(ON)

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23

S5#

This pin accepts the SLP_S5# sleep state signal.

For the VDDQ synchronous DC-DC buck converter, connect the PHASE pin

to the upper N-MOSFET's source. This pin is used to monitor the voltage

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PHASE

drop across the upper N-MOSFET for over-current protection. The PHASE

pin is the return path rail for the upper MOSFET deriver (UGATE).

For the VDDQ synchronous DC-DC buck converter, the BOOT pin provides

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BOOT

as power supply to the upper N-MOSFET driver. A bootstrap circuit is used

to create a voltage suitable to drive a logic-level N-MOSFET.

For the VDDQ synchronous DC-DC buck converter, connect the UGATE pin

to the upper N-MOSFET's gate. This pin provides the PWM-controlled gate

drive for the upper N-MOSFET. This pin is also monitored by the adaptive

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UGATE shootthrough protection circuitry to determine when the upper N- MOSFET

has turned off. Do not insert any circuitry between this pin and the gate of

the upper N-MOSFET, as it may interfere with the internal adaptive

shoot-through protection circuitry and render it ineffective.

For the VDDQ synchronous DC-DC buck converter, Connect the LGATE pin

to the lower N-MOSFET's gate. This pin provides the PWM-controlled gate

drive for the lower N-MOSFET. This pin is also monitored by the adaptive

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LGATE shootthrough protection circuitry to determine when the lower N- MOSFET

has turned off. Do not insert any circuitry between this pin and the gate of

the lower N-MOSFET, as it may interfere with the internal adaptive

shoot-through protection circuitry and render it ineffective.

www.richtek.com

6

DS9644/A-01 August 2007

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