Richtek RT8856GQW Schematic [ru]

®

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

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
8