RT8857 데이터 시트보기 (PDF) - Richtek Technology

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RT8857

4/3/2/1-Phase PWM Controller with Embedded Drivers for CPU Core Power Supply

Richtek Technology 

RT8857/A

Functional Pin Description

Pin No.

Pin Name

Pin Function

1

FBRTN

Negative Remote Sense Pin of Output Voltage.

2

QR1

Quick Response Setting Pins for Load Transition.

3

QR2

Quick Response Setting Pins for Load Transition.

4

SS/EN

Connect this pin to GND by a capacitor to adjust soft start time.

Pull this pin to GND to disable controller.

5

COMP

Output of error-amp and input of PWM comparator.

6

FB

Inverting input of error-amp.

7

OFS

Connect this pin to GND or 5V by a resistor to set no-load offset voltage.

8

RT

Connect this pin to GND by a resistor to adjust frequency.

9

ADJ

Connect this pin to GND by a resistor to set load line.

10

IMAX

Negative input of OCP comparator. (Positive input of OCP comparator

is ADJ).

11

IMAXPSI

OCP Setting in Power Saving Mode.

12

IMONFB

Current Monitor Gain/Offset Adjustment.

13

IMON

Current Monitor Output.

14, 17, 18, 21 ISP4, ISP3, ISP2, ISP1 Positive current sense pin of channel 1, 2, 3 and 4.

15, 16, 19, 20 ISN4, ISN3, ISN2, ISN1 Negative current sense pin of channel 1, 2, 3 and 4.

22

VRHOT

Temperature Monitor Output.

23

TSEN

Temperature Sense Input.

24

VCC5

5V LDO Output for System Power Supply.

25, 26

PWM4, PWM3

PWM Output for Channel 4 and Channel 3.

27, 35

BOOT2, BOOT1

Bootstrap Supply for Channel 2 and Channel 1.

28, 34

UGATE2, UGATE1

Upper Gate Driver for Channel 2 and Channel 1.

29, 33

PHASE2, PHASE1

Switching Node of Channel 2 and Channel 1.

30, 32

LGATE2, LGATE1

Lower Gate Driver for Channel 2 and Channel 1.

31

VCC12

IC Power Supply. Connect to 12V.

36

PWRGD

Power Good Indicator.

37

EN/VTT

VTT Voltage Detector Input.

38 to 45

VID7 to VID0

Voltage Identification Input for DAC.

47

PSI

Power Status Indicator II.

48

VOUT

Feedback of Regulated Output.

46

VIDSEL

VID DAC Selection Pin.

49

GND

(Exposed pad)

The exposed pad must be soldered to a large PCB and connected to

GND for maximum power dissipation.

VID Table Selection

VIDSEL VID [7] Table

VTT

X

VR11

GND

X

VR1 0.x

VCC5 VTT

K8

VCC5 GND K8_M2

DS8857/A-01 April 2011

www.richtek.com

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