Richtek RT8856GQW Schematic [ru]

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®

RT8856

Multi-Phase PWM Controller for CPU Core Power Supply

General Description

The RT8856 is a single/dual phase PWM controller with two integrated MOSFET drivers. Moreover, it is compliant with Intel IMVP6.5 Voltage Regulator Specification to fulfill its mobile CPU Vcore power supply requirements. The RT8856 adopts NAVPTM (Native AVP) which is Richtek's proprietary topology derived from finite DC gain compensator peak current mode, making it an easy setting PWM controller that meets all Intel AVP (Active Voltage Positioning) mobile CPU requirements.

The output voltage of the RT8856 is set by 7-bit VID code. The built-in high accuracy DAC converts the VID code ranging from 0V to 1.5V with 12.5mV per step. The system accuracy of the controller can reach 1.5%. The part supports VID on-the-fly and mode change on-the-fly functions that are fully compliant with IMVP6.5 specification. It operates in single phase, dual phase and RFM. It can reach up to 90% efficiency in different modes according to different loading conditions. The droop load line can be easily programmed by setting the DC gain of the error amplifier. With proper compensation, the load transient can achieve optimized AVP performance. This chip controls soft-start and output transition slew rate via a capacitor. It supports both DCR and sense resistor current sensing. The current mode NAVPTM topology with high accuracy current sensing amplifier well balances the RT8856's channel currents.

The RT8856 provides power good, clock enabling and thermal throttling output signals for IMVP6.5 specification. It also features complete fault protection functions including over voltage, under voltage, negative voltage, over current, thermal shutdown, and under voltage lockout.

The RT8856 is available in a WQFN-40L 6x6 small foot print package.

Features

1/2 Phase PWM Controller with 2 Integrated MOSFET Drivers

IMVP6.5 Compatible Power Management States (DPSRLVR, PSI, Extended Deeper Sleep Mode)

NAVP (Native AVP) Topology

7-bit DAC

0.8% DAC Accuracy

Fixed VBOOT (1.1V)

Differential Remote Voltage Sensing

Programmable Output Transition Slew Rate Control

Accurate Current and Thermal Balance

System Thermal Compensation AVP

Ringing Free Mode at Light Load Conditions

Fast Transient Response

Power Good

Clock Enable Output

Thermal Throttling

Current Monitor Output

Switching Frequency up to 1MHz Per Phase

OVP, UVP, NVP, OCP, OTP, UVLO

40-Lead WQFN Package

RoHS Compliant and Halogen Free

Ordering Information

RT8856

Package Type

QW : WQFN-40L 6X6 (W-Type) (Exposed Pad-Option 1)

Lead Plating System

G : Green (Halogen Free and Pb Free)

Note :

Richtek products are :

RoHS compliant and compatible with the current requirements of IPC/JEDEC J-STD-020.

Suitable for use in SnPb or Pb-free soldering processes.

Applications

IMVP6.5 Core Supply

Multi-phase CPU Core Supply

AVP Step-Down Converter

Notebook/ Desktop Computer/ Servers

Copyright ©2014 Richtek Technology Corporation. All rights reserved.

is a registered trademark of Richtek Technology Corporation.

DS8856-04 August 2014

www.richtek.com

 

1

Richtek RT8856GQW Schematic

RT8856

Marking Information

Pin Configurations

RT8856

RT8856GQW : Product Number

YMDNN : Date Code

GQW

 

YMDNN

 

 

 

(TOP VIEW)

 

PGOOD

CLKEN

VCC

TON

VRTT NTC

OCSET

ISEN2

ISEN2N

BOOT2

 

 

40

39

38

37

36

35

34

33

32

31

 

DPRSLPVR

1

 

 

 

 

 

 

 

 

30

UGATE2

VRON

2

 

 

 

 

 

 

 

 

29

PHASE2

FS

3

 

 

 

 

 

 

 

 

28

PGND2

CM

4

 

 

 

 

 

 

 

 

27

LGATE2

CMSET

5

 

 

 

GND

 

 

 

26

PVCC

VID6

6

 

 

 

 

 

 

25

LGATE1

 

 

 

 

 

 

 

 

VID5

7

 

 

 

 

 

 

 

 

24

PGND1

VID4

8

 

 

 

 

 

 

41

23

PHASE1

VID3

9

 

 

 

 

 

 

22

UGATE1

 

 

 

 

 

 

 

 

VID2

10

 

 

 

 

 

 

 

 

21

BOOT1

 

11

12

13

14

15

16

17

18

19

20

 

 

VID1

VID0

PSI

COMP

FB

VSEN

RGND

SOFT

ISEN1

ISEN1 N

 

 

 

WQFN-40L 6x6

 

 

 

Typical Application Circuit

 

 

 

V

 

 

 

38

 

 

 

 

 

 

 

 

 

 

CC

 

 

 

12

 

 

 

 

 

C3

VID0

 

 

 

 

 

 

 

 

 

 

 

 

11

 

 

 

 

 

 

VID1

 

 

 

 

 

 

10

 

 

 

 

 

 

VID2

 

 

 

 

 

 

9

 

 

 

 

 

 

VID3

 

 

3.3V

 

 

 

8

 

 

 

 

 

VID4

 

 

 

 

 

 

 

 

 

 

 

 

7

 

 

 

 

 

 

VID5

 

 

 

 

R7

R8

6

 

 

Vccp

VID6

 

 

 

 

 

 

 

 

13

 

 

 

 

 

 

 

 

 

 

 

PSI

 

 

 

 

 

 

 

 

 

 

 

 

DPRSLPVR

1

 

 

 

 

 

2

 

 

R11

 

 

VRON

 

 

 

 

 

 

 

PWRGD

 

 

 

 

 

40

 

 

 

 

 

39

 

CLKEN

 

 

 

 

 

 

 

 

 

 

 

36

 

VRTT

 

 

 

 

 

 

 

 

 

 

 

4

 

CM

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

C12

R15

 

R18

5

CPU V

SENSE

 

 

 

 

 

16

SS

 

 

 

 

 

 

 

 

 

 

C14

 

15

 

 

 

 

C15

 

 

 

 

 

 

 

V

R20

R21

R22

R23

14

 

 

 

 

 

 

 

OUT

 

 

 

 

 

 

 

 

 

 

NTC1

C18

 

CPU VCC

SENSE

 

 

R24

 

3

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

R25

 

V

5V

IN

7V to 24V

R1

 

 

 

 

 

 

 

 

 

 

 

RT8856

 

 

C1

 

 

 

 

 

 

 

26

 

 

 

 

 

 

 

 

 

VCC

PVCC

 

 

 

C2

 

 

 

 

 

 

R2

C4

 

 

 

 

 

VID0

BOOT1

21

 

 

 

 

 

 

22

 

 

Q1

 

 

 

 

 

 

VID1

UGATE1

 

 

 

 

 

 

 

 

R3

 

 

 

 

 

L1

 

 

 

 

 

 

 

 

 

 

VID2

PHASE1

23

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Q2

 

 

 

 

 

 

VID3

LGATE1

25

R4

 

R5

D1

 

R6

 

C6

 

 

 

 

VID4

 

 

 

 

PGND1

24

 

 

 

C5

 

 

 

 

 

VID5

 

 

 

 

 

 

 

 

19

 

 

 

 

 

 

 

 

 

ISEN1

 

 

 

 

 

 

 

 

 

VID6

 

 

 

 

 

 

 

 

 

20

 

 

 

 

 

 

 

 

 

ISEN1_N

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

C7

PSI

 

 

 

 

 

V

 

 

 

 

 

 

 

 

 

 

 

 

 

 

31

R9

C9

 

 

IN

 

 

 

 

 

BOOT2

Q3

C8

7V to 21V

 

 

DPRSLPVR

 

 

 

 

30

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

UGATE2

 

 

 

 

 

 

 

 

 

VRON

R10

 

 

 

 

 

L2

 

 

 

 

 

 

 

 

 

 

 

29

 

 

 

 

 

 

 

PGOOD

PHASE2

 

 

 

 

 

 

 

 

V

 

 

 

 

 

 

 

 

 

 

 

R12

 

Q4

 

 

 

 

 

OUT

CLKEN

LGATE2

27

 

R13

D2

 

R14

C10

 

 

 

 

 

 

 

VRTT

PGND2

28

 

 

 

C9

 

 

 

 

C11

CM

 

 

 

 

 

 

 

 

 

 

37

R16

 

R17

 

 

 

 

 

 

 

TON

 

V

 

 

 

 

 

 

 

 

 

 

 

 

 

 

CMSET

 

 

 

C13

IN

 

 

 

 

 

 

 

 

 

 

 

 

 

 

VSEN

 

 

 

 

 

 

 

 

 

ISEN2

33

 

 

 

 

 

 

 

 

 

FB

 

 

 

 

 

 

 

 

 

32

 

 

 

 

 

 

 

 

 

ISEN2_N

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

18

 

 

 

R19

 

 

 

 

C16

 

SOFT

 

 

 

 

 

 

 

 

 

C17

 

 

 

 

 

 

 

COMP

RGND

17

 

 

 

CPU V

 

SENSE

 

 

 

 

 

 

 

NTC

35

 

 

 

 

 

 

SS

 

 

R26

 

 

 

 

 

 

 

 

 

R27

R28

 

 

 

 

 

FS

OCSET

34

 

V

CC

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

GND

 

 

R29

 

 

NTC2

 

 

 

 

 

41 (Exposed pad)

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Copyright ©2014 Richtek Technology Corporation. All rights reserved.

is a registered trademark of Richtek Technology Corporation.

www.richtek.com

DS8856-04 August 2014

2

 

RT8856

Table 1. IMVP6.5 VID code table

VID6

VID5

VID4

VID3

VID2

VID1

VID0

Output

 

 

 

 

 

 

 

 

0

0

0

0

0

0

0

1.5000V

 

 

 

 

 

 

 

 

0

0

0

0

0

0

1

1.4875V

 

 

 

 

 

 

 

 

0

0

0

0

0

1

0

1.4750V

 

 

 

 

 

 

 

 

0

0

0

0

0

1

1

1.4625V

 

 

 

 

 

 

 

 

0

0

0

0

1

0

0

1.4500V

 

 

 

 

 

 

 

 

0

0

0

0

1

0

1

1.4375V

 

 

 

 

 

 

 

 

0

0

0

0

1

1

0

1.4250V

 

 

 

 

 

 

 

 

0

0

0

0

1

1

1

1.4125V

 

 

 

 

 

 

 

 

0

0

0

1

0

0

0

1.4000V

 

 

 

 

 

 

 

 

0

0

0

1

0

0

1

1.3875V

 

 

 

 

 

 

 

 

0

0

0

1

0

1

0

1.3750V

 

 

 

 

 

 

 

 

0

0

0

1

0

1

1

1.3625V

 

 

 

 

 

 

 

 

0

0

0

1

1

0

0

1.3500V

 

 

 

 

 

 

 

 

0

0

0

1

1

0

1

1.3375V

 

 

 

 

 

 

 

 

0

0

0

1

1

1

0

1.3250V

 

 

 

 

 

 

 

 

0

0

0

1

1

1

1

1.3125V

 

 

 

 

 

 

 

 

0

0

1

0

0

0

0

1.3000V

 

 

 

 

 

 

 

 

0

0

1

0

0

0

1

1.2875V

 

 

 

 

 

 

 

 

0

0

1

0

0

1

0

1.2750V

 

 

 

 

 

 

 

 

0

0

1

0

0

1

1

1.2625V

 

 

 

 

 

 

 

 

0

0

1

0

1

0

0

1.2500V

 

 

 

 

 

 

 

 

0

0

1

0

1

0

1

1.2375V

 

 

 

 

 

 

 

 

0

0

1

0

1

1

0

1.2250V

 

 

 

 

 

 

 

 

0

0

1

0

1

1

1

1.2125V

 

 

 

 

 

 

 

 

0

0

1

1

0

0

0

1.2000V

 

 

 

 

 

 

 

 

0

0

1

1

0

0

1

1.1875V

 

 

 

 

 

 

 

 

0

0

1

1

0

1

0

1.1750V

 

 

 

 

 

 

 

 

0

0

1

1

0

1

1

1.1625V

 

 

 

 

 

 

 

 

0

0

1

1

1

0

0

1.1500V

 

 

 

 

 

 

 

 

0

0

1

1

1

0

1

1.1375V

 

 

 

 

 

 

 

 

0

0

1

1

1

1

0

1.1250V

 

 

 

 

 

 

 

 

0

0

1

1

1

1

1

1.1125V

 

 

 

 

 

 

 

 

0

1

0

0

0

0

0

1.1000V

 

 

 

 

 

 

 

 

VID6

VID5

VID4

VID3

VID2

VID1

VID0

Output

 

 

 

 

 

 

 

 

0

1

0

0

0

0

1

1.0875V

 

 

 

 

 

 

 

 

0

1

0

0

0

1

0

1.0750V

 

 

 

 

 

 

 

 

0

1

0

0

0

1

1

1.0625V

 

 

 

 

 

 

 

 

0

1

0

0

1

0

0

1.0500V

 

 

 

 

 

 

 

 

0

1

0

0

1

0

1

1.0375V

 

 

 

 

 

 

 

 

0

1

0

0

1

1

0

1.0250V

 

 

 

 

 

 

 

 

0

1

0

0

1

1

1

1.0125V

 

 

 

 

 

 

 

 

0

1

0

1

0

0

0

1.0000V

 

 

 

 

 

 

 

 

0

1

0

1

0

0

1

0.9875V

 

 

 

 

 

 

 

 

0

1

0

1

0

1

0

0.9750V

 

 

 

 

 

 

 

 

0

1

0

1

0

1

1

0.9625V

 

 

 

 

 

 

 

 

0

1

0

1

1

0

0

0.9500V

 

 

 

 

 

 

 

 

0

1

0

1

1

0

1

0.9375V

 

 

 

 

 

 

 

 

0

1

0

1

1

1

0

0.9250V

 

 

 

 

 

 

 

 

0

1

0

1

1

1

1

0.9125V

 

 

 

 

 

 

 

 

0

1

1

0

0

0

0

0.9000V

 

 

 

 

 

 

 

 

0

1

1

0

0

0

1

0.8875V

 

 

 

 

 

 

 

 

0

1

1

0

0

1

0

0.8750V

 

 

 

 

 

 

 

 

0

1

1

0

0

1

1

0.8625V

 

 

 

 

 

 

 

 

0

1

1

0

1

0

0

0.8500V

 

 

 

 

 

 

 

 

0

1

1

0

1

0

1

0.8375V

 

 

 

 

 

 

 

 

0

1

1

0

1

1

0

0.8250V

 

 

 

 

 

 

 

 

0

1

1

0

1

1

1

0.8125V

 

 

 

 

 

 

 

 

0

1

1

1

0

0

0

0.8000V

 

 

 

 

 

 

 

 

0

1

1

1

0

0

1

0.7875V

 

 

 

 

 

 

 

 

0

1

1

1

0

1

0

0.7750V

 

 

 

 

 

 

 

 

0

1

1

1

0

1

1

0.7625V

 

 

 

 

 

 

 

 

0

1

1

1

1

0

0

0.7500V

 

 

 

 

 

 

 

 

0

1

1

1

1

0

1

0.7375V

 

 

 

 

 

 

 

 

0

1

1

1

1

1

0

0.7250V

 

 

 

 

 

 

 

 

0

1

1

1

1

1

1

0.7125V

 

 

 

 

 

 

 

 

1

0

0

0

0

0

0

0.7000V

 

 

 

 

 

 

 

 

1

0

0

0

0

0

1

0.6875V

 

 

 

 

 

 

 

 

Copyright ©2014 Richtek Technology Corporation. All rights reserved.

is a registered trademark of Richtek Technology Corporation.

DS8856-04 August 2014

www.richtek.com

 

3

RT8856

VID6

VID5

VID4

VID3

VID2

VID1

VID0

Output

 

 

 

 

 

 

 

 

1

0

0

0

0

1

0

0.6750V

 

 

 

 

 

 

 

 

1

0

0

0

0

1

1

0.6625V

 

 

 

 

 

 

 

 

1

0

0

0

1

0

0

0.6500V

 

 

 

 

 

 

 

 

1

0

0

0

1

0

1

0.6375V

 

 

 

 

 

 

 

 

1

0

0

0

1

1

0

0.6250V

 

 

 

 

 

 

 

 

1

0

0

0

1

1

1

0.6125V

 

 

 

 

 

 

 

 

1

0

0

1

0

0

0

0.6000V

 

 

 

 

 

 

 

 

1

0

0

1

0

0

1

0.5875V

 

 

 

 

 

 

 

 

1

0

0

1

0

1

0

0.5750V

 

 

 

 

 

 

 

 

1

0

0

1

0

1

1

0.5625V

 

 

 

 

 

 

 

 

1

0

0

1

1

0

0

0.5500V

 

 

 

 

 

 

 

 

1

0

0

1

1

0

1

0.5375V

 

 

 

 

 

 

 

 

1

0

0

1

1

1

0

0.5250V

 

 

 

 

 

 

 

 

1

0

0

1

1

1

1

0.5125V

 

 

 

 

 

 

 

 

1

0

1

0

0

0

0

0.5000V

 

 

 

 

 

 

 

 

1

0

1

0

0

0

1

0.4875V

 

 

 

 

 

 

 

 

1

0

1

0

0

1

0

0.4750V

 

 

 

 

 

 

 

 

1

0

1

0

0

1

1

0.4625V

 

 

 

 

 

 

 

 

1

0

1

0

1

0

0

0.4500V

 

 

 

 

 

 

 

 

1

0

1

0

1

0

1

0.4375V

 

 

 

 

 

 

 

 

1

0

1

0

1

1

0

0.4250V

 

 

 

 

 

 

 

 

1

0

1

0

1

1

1

0.4125V

 

 

 

 

 

 

 

 

1

0

1

1

0

0

0

0.4000V

 

 

 

 

 

 

 

 

1

0

1

1

0

0

1

0.3875V

 

 

 

 

 

 

 

 

1

0

1

1

0

1

0

0.3750V

 

 

 

 

 

 

 

 

1

0

1

1

0

1

1

0.3625V

 

 

 

 

 

 

 

 

1

0

1

1

1

0

0

0.3500V

 

 

 

 

 

 

 

 

1

0

1

1

1

0

1

0.3375V

 

 

 

 

 

 

 

 

1

0

1

1

1

1

0

0.3250V

 

 

 

 

 

 

 

 

1

0

1

1

1

1

1

0.3125V

 

 

 

 

 

 

 

 

1

1

0

0

0

0

0

0.3000V

 

 

 

 

 

 

 

 

VID6

VID5

VID4

VID3

VID2

VID1

VID0

Output

 

 

 

 

 

 

 

 

1

1

0

0

0

0

1

0.2875V

 

 

 

 

 

 

 

 

1

1

0

0

0

1

0

0.2750V

 

 

 

 

 

 

 

 

1

1

0

0

0

1

1

0.2625V

 

 

 

 

 

 

 

 

1

1

0

0

1

0

0

0.2500V

 

 

 

 

 

 

 

 

1

1

0

0

1

0

1

0.2375V

 

 

 

 

 

 

 

 

1

1

0

0

1

1

0

0.2250V

 

 

 

 

 

 

 

 

1

1

0

0

1

1

1

0.2125V

 

 

 

 

 

 

 

 

1

1

0

1

0

0

0

0.2000V

 

 

 

 

 

 

 

 

1

1

0

1

0

0

1

0.1875V

 

 

 

 

 

 

 

 

1

1

0

1

0

1

0

0.1750V

 

 

 

 

 

 

 

 

1

1

0

1

0

1

1

0.1625V

 

 

 

 

 

 

 

 

1

1

0

1

1

0

0

0.1500V

 

 

 

 

 

 

 

 

1

1

0

1

1

0

1

0.1375V

 

 

 

 

 

 

 

 

1

1

0

1

1

1

0

0.1250V

 

 

 

 

 

 

 

 

1

1

0

1

1

1

1

0.1125V

 

 

 

 

 

 

 

 

1

1

1

0

0

0

0

0.1000V

 

 

 

 

 

 

 

 

1

1

1

0

0

0

1

0.0875V

 

 

 

 

 

 

 

 

1

1

1

0

0

1

0

0.0750V

 

 

 

 

 

 

 

 

1

1

1

0

0

1

1

0.0625V

 

 

 

 

 

 

 

 

1

1

1

0

1

0

0

0.0500V

 

 

 

 

 

 

 

 

1

1

1

0

1

0

1

0.0375V

 

 

 

 

 

 

 

 

1

1

1

0

1

1

0

0.0250V

 

 

 

 

 

 

 

 

1

1

1

0

1

1

1

0.0125V

 

 

 

 

 

 

 

 

1

1

1

1

0

0

0

0.0000V

 

 

 

 

 

 

 

 

1

1

1

1

0

0

1

0.0000V

 

 

 

 

 

 

 

 

1

1

1

1

0

1

0

0.0000V

 

 

 

 

 

 

 

 

1

1

1

1

0

1

1

0.0000V

 

 

 

 

 

 

 

 

1

1

1

1

1

0

0

0.0000V

 

 

 

 

 

 

 

 

1

1

1

1

1

0

1

0.0000V

 

 

 

 

 

 

 

 

1

1

1

1

1

1

0

0.0000V

 

 

 

 

 

 

 

 

1

1

1

1

1

1

1

0.0000V

 

 

 

 

 

 

 

 

Copyright ©2014 Richtek Technology Corporation. All rights reserved.

is a registered trademark of Richtek Technology Corporation.

www.richtek.com

DS8856-04 August 2014

4

 

RT8856

Functional Pin Description

 

Pin No.

 

Pin Name

 

Pin Function

 

 

 

 

 

Deeper Sleep Mode Signal. Together with

 

the combination of these two pins

 

1

 

DPRSLPVR

PSI,

 

 

indicates the power management states.

 

 

 

 

 

 

2

 

VRON

Voltage Regulator Enabler.

 

 

 

 

3

 

FS

Frequency Setting. Connect this pin with a resistor to ground to set the operating

 

 

frequency.

 

 

 

 

 

 

 

 

 

 

 

 

4

 

CM

Current Monitor Output. This

pin outputs a voltage proportional to the output

 

 

current.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Current Monitor Output Gain Externally Setting. Connect this pin with one resistor

 

5

 

CMSET

to VSEN while CM pin is connected to ground with another resistor. The current

 

 

 

 

 

monitor output gain can be set by the ratio of these two resistors.

 

 

 

 

 

Voltage ID. DAC voltage identification inputs for IMVP6.5.

 

6 to 12

 

VID[6:0]

The logic threshold is 30% of VCCP as the maximum value for low state and 70%

 

 

 

 

 

of VCCP as the minimum value for the high state. VCCP is 1.05V.

 

 

 

 

 

Power Status Indicator II. Together with DPRSLPVR, the combination of these two

 

13

 

PSI

 

 

pins indicates the power management states.

 

 

 

 

 

 

14

 

COMP

Compensation. This pin is the output node of the error amplifier.

 

15

 

FB

Feedback. This is the negative input node of the error amplifier.

 

16

 

VSEN

Positive Voltage Sensing Pin. This pin is the positive node of the differential

 

 

voltage sensing.

 

 

 

 

 

 

 

 

 

 

 

 

17

 

RGND

Return Ground. This pin is the negative node of the differential remote voltage

 

 

sensing.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Soft-Start. This pin provides soft-start function and slew rate control. The

 

 

 

 

 

capacitance of the slew rate control capacitor is restricted to be larger than 10nF.

 

18

 

SOFT

The feedback voltage of the converter follows the ramping voltage on the SOFT pin

 

 

 

 

 

during soft-start and other voltage transitions according to different modes of

 

 

 

 

 

operation and VID change.

 

 

 

 

19

 

ISEN1

Positive Input of Phase1 Current Sense.

 

20

 

ISEN1_N

Negative Input of Phase1 Current Sense.

 

 

 

 

 

Bootstrap Power Pin of Phase1. This pin powers the high side MOSFET drivers.

 

21

 

BOOT1

Connect this pin to the junction of the bootstrap capacitor with the cathode of the

 

 

 

 

 

bootstrap diode. Connect the anode of the bootstrap diode to the PVCC pin.

 

22

 

UGATE1

Upper Gate Drive of Phase1. This pin drives the gate of the high side MOSFETs.

 

23

 

PHASE1

Return Node of Phase1 High Side Driver. Connect this pin to high side MOSFET

 

 

sources together with the low side MOSFET drains and the inductor.

 

 

 

 

 

 

24

 

PGND1

Driver Ground of Phase1.

 

 

 

 

25

 

LGATE1

Lower Gate Drive of Phase1. This pin drives the gate of the low side MOSFETs.

 

26

 

PVCC

Driver Power.

 

 

 

 

27

 

LGATE2

Lower Gate Drive of Phase2. This pin drives the gate of the low side MOSFETs.

 

28

 

PGND2

Driver Ground of Phase2.

 

 

 

 

29

 

PHASE2

Return Node of Phase2 High Side Driver. Connect this pin to high side MOSFET

 

 

sources together with the low side MOSFET drains and the inductor.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Copyright ©2014 Richtek Technology Corporation. All rights reserved.

is a registered trademark of Richtek Technology Corporation.

DS8856-04 August 2014

www.richtek.com

 

5

RT8856

Pin No.

 

Pin Name

 

Pin Function

30

 

UGATE2

Upper Gate Drive of Phase2. This pin drives the gate of the high side

 

MOSFETs.

 

 

 

 

 

 

 

 

 

 

 

 

Bootstrap Power Pin of Phase2. This pin powers the high side MOSFET drivers.

31

 

BOOT2

Connect this pin to the junction of the bootstrap capacitor with the cathode of the

 

 

 

 

 

 

bootstrap diode. Connect the anode of the bootstrap diode to the PVCC pin.

32

 

ISEN2_N

Negative Input of Phase2 Current Sense.

33

 

ISEN2

Positive input of Phase2 Current Sense.

 

 

 

 

 

 

Over Current Protection Setting. Connect a resistive voltage divider from VCC to

34

 

OCSET

ground and connect the joint of the voltage divider to the OCSET pin. The

 

 

 

 

 

 

voltage, VOCSET, determines the over current threshold, ILIM.

 

 

 

 

 

 

Thermal Detection Input for

 

Circuit. Connect this pin with a resistive

 

 

 

 

 

 

VRTT

35

 

NTC

voltage divider from VCC using NTC on the top to set the thermal management

 

 

 

 

 

 

threshold level.

36

 

 

 

 

 

Voltage Regulator Thermal Throttling. This open-drain output pin indicates the

 

VRTT

 

temperature exceeding the preset level when it is pulled low.

 

 

 

 

 

 

37

 

TON

Connect this pin to VIN with one resistor. This resistor value sets the ripple size

 

in ringing free mode.

 

 

 

 

 

 

38

 

VCC

Chip Power.

39

 

 

 

 

 

Inverted Clock Enable. This open-drain pin is an output indicating the start of the

 

 

CLKEN

 

PLL locking of the clock chip.

 

 

 

 

 

 

40

 

PGOOD

Power Good Indicator.

41 (Exposed Pad)

 

GND

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

 

GND for maximum power dissipation.

 

 

 

 

 

 

Copyright ©2014 Richtek Technology Corporation. All rights reserved.

is a registered trademark of Richtek Technology Corporation.

www.richtek.com

DS8856-04 August 2014

6

 

RT8856

Function Block Diagram

 

 

BOOT1

UGATE1

PHASE1 PVCC

LGATE1

PGND1 BOOT2

UGATE2

PHASE2

LGATE2

PGND2

ISEN1 N

ISEN1

 

ISEN2 N

ISEN2

CM CMSET

 

 

 

 

 

 

 

 

 

 

 

+

-

 

+

-

 

 

 

 

 

 

 

 

 

 

 

 

20

 

ONE PHASE

20

 

FS

 

OSC

 

 

Driver Logic Control

PWMCP

 

PWMCP

1/2

 

 

 

 

CM

TON

FB

Ringing Free Mode

 

 

 

+ -

+ -

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

OCSET

 

OCP Setting

 

 

 

 

 

 

 

 

 

 

+

 

 

 

PSI

 

Mode Selection

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

VRON VCC DPRSLPVR

 

Power On Reset & Central Logic

 

+ -

+ -

OTP

 

 

 

 

 

 

Offset Cancellation

 

 

 

PGOODCLKEN

 

 

 

+

+ -

+ -

 

 

 

 

 

 

 

 

 

 

 

NVPTrip Point -

 

OVPTrip Point

UVPTrip Point

 

 

ERROR

AMP

 

 

 

 

 

 

 

 

 

+ -

 

 

 

VRTT

 

 

 

 

 

 

 

 

 

SOFT START

 

 

 

 

 

 

 

 

+ -

 

 

 

MUX

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

NTC

VCC

 

 

 

1.2V

 

 

DAC

 

 

 

 

 

 

 

 

 

 

 

 

GND

 

 

VID0 VID1 VID2 VID3 VID4 VID5 VID6

RGND

 

 

SOFT FB

COMP VSEN

Copyright ©2014 Richtek Technology Corporation. All rights reserved.

is a registered trademark of Richtek Technology Corporation.

DS8856-04 August 2014

www.richtek.com

 

7

RT8856

Absolute Maximum Ratings

(Note 1)

 

 

 

 

 

 

VCC to GND ------------------------------------------------------------------------------------------------

 

 

 

 

−0.3V to 6.5V

 

RGND, PGNDx to GND ----------------------------------------------------------------------------------

 

 

 

 

−0.3V to 0.3V

 

VIDx to GND ------------------------------------------------------------------------------------------------

 

 

 

 

−0.3V to (VCC + 0.3V)

 

VRON to GND

 

 

 

 

−0.3V to (VCC + 0.3V)

PSI,

 

 

 

 

PGOOD,

CLKEN,

 

VRTT

-----------------------------------------------------------------------to GND

 

 

 

−0.3V to (VCC + 0.3V)

VSEN, FB, COMP, SOFT, FS, OCSET, CM, CMSET, NTC to GND ---------------------------

 

−0.3V to (VCC + 0.3V)

ISENx, ISEN1_N, ISEN2_N to GND -----------------------------------------------------------------

 

 

 

−0.3V to (VCC + 0.3V)

PVCC to PGNDx ------------------------------------------------------------------------------------------

 

 

 

 

−0.3V to 6.5V

 

LGATEx to PGNDx ---------------------------------------------------------------------------------------

 

 

 

 

−0.3V to (PVCC + 0.3V)

PHASEx to PGNDx --------------------------------------------------------------------------------------

 

 

 

 

−3V to 28V

 

 

BOOTx to PHASEx ---------------------------------------------------------------------------------------

 

 

 

 

−0.3V to 6.5V

 

UGATEx to PHASEx -------------------------------------------------------------------------------------

 

 

 

 

−0.3V to (BOOTx − PHASEx)

PGOOD ------------------------------------------------------------------------------------------------------

 

 

 

 

−0.3V to (VCC + 0.3V)

Power Dissipation, PD @ TA = 25°C

 

 

 

 

 

 

 

 

 

WQFN−40L 6x6 --------------------------------------------------------------------------------------------

 

 

 

 

2.941W

 

 

Package Thermal Resistance (Note 2)

 

 

 

 

 

 

 

 

 

WQFN-40L 6x6, θJA ---------------------------------------------------------------------------------------

 

 

 

 

34°C/W

 

 

 

 

WQFN-40L 6x6, θJC --------------------------------------------------------------------------------------

 

 

 

 

6°C/W

 

 

Junction Temperature -------------------------------------------------------------------------------------

 

 

 

 

150°C

 

 

Lead Temperature (Soldering, 10 sec.) ---------------------------------------------------------------

 

 

 

260°C

 

 

Storage Temperature Range ----------------------------------------------------------------------------

 

 

 

−65°C to 150°C

 

ESD Susceptibility (Note 3)

 

 

 

 

 

 

 

 

 

HBM (Human Body Mode)

------------------------------------------------------------------------------

 

 

 

2kV

 

 

 

 

MM (Machine Mode) --------------------------------------------------------------------------------------

 

 

 

 

200V

 

 

Recommended Operating Conditions

(Note 4)

 

 

 

 

 

Supply Voltage, VCC --------------------------------------------------------------------------------------

 

 

 

 

4.5V to 5.5V

 

Battery Voltage, VIN --------------------------------------------------------------------------------------

 

 

 

 

7V to 24V

 

 

Junction Temperature Range ----------------------------------------------------------------------------

 

 

 

−40°C to 125°C

 

Ambient Temperature Range ----------------------------------------------------------------------------

 

 

 

−40°C to 85°C

 

Electrical Characteristics

 

 

 

 

 

 

 

(VCC = 5V, TA = 25°C, unless otherwise specified)

 

 

 

 

 

 

 

 

 

Parameter

Symbol

Test Conditions

Min

Typ

 

Max

Unit

 

Supply Input

 

 

 

 

 

 

 

 

 

Supply Current

IVCC + IPVCC

RFS = 33k , VVRON = 3.3V,

--

--

 

10

mA

 

Not Switching

 

 

 

Shutdown Current

ICC + IPVCC

VVRON = 0V

 

--

--

 

5

A

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Soft-Start/Slew Rate Control (based on 10nF CSS)

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Soft-Start / Soft-Shutdown

ISS1

VSOFT = 1.5V

 

16

20

 

24

A

 

Deeper Sleep Exit/VID

ISS2

VSOFT = 1.5V

 

80

100

 

120

A

 

Change Slew Current

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Copyright ©2014 Richtek Technology Corporation. All rights reserved.

is a registered trademark of Richtek Technology Corporation.

www.richtek.com

DS8856-04 August 2014

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