Richtek RT8813CGQW Schematic [ru]

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RT8813C

Multi-Phase PWM Controller with PWM-VID Reference

General Description

The RT8813C is a 3/2/1 phase synchronous Buck PWM controller which is optimized for high performance graphic microprocessor and computer applications. The IC integrates a Constant-On-Time (COT) PWM controller, two MOSFET drivers with internal bootstrap diodes, as well as channel current balance and protection functions including Over-Voltage Protection (OVP), Under-Voltage Protection (UVP), current limit, and thermal shutdown into the WQFN-24L 4x4 package.

The RT8813C adopts RDS(ON) current sensing technique. Current limit is accomplished through continuous inductor- current-sense, while RDS(ON) current sensing is used for accurate channel current balance. Using the method of current sampling utilizes the best advantages of each technique.

The RT8813C features external reference input and PWMVID dynamic output voltage control, in which the feedback voltage is regulated and tracks external input reference voltage. Other features include adjustable switching frequency, dynamic phase number control, internal/external soft-start, power good indicator, and enable functions.

Features

Multi-Phase PWM Controller

Two Embedded MOSFET Drivers and Embedded Switching Boot Diode

External Reference Input Control

PWM-VID Dynamic Voltage Control

Dynamic Phase Number Control

Lossless RDS(ON) Current Sensing for Current Balance

Internal Fixed and External Adjustable Soft-Start

Adjustable Current Limit Threshold

Adjustable Switching Frequency

UVP/OVP Protection

Shoot Through Protection and Short Pulse Free Technology

Support an Ultra-Low Output Voltage as Standby Voltage

Thermal Alert Indicator in 2/1 Active Phase Application

Thermal Shutdown

Power Good Indicator

RoHS Compliant and Halogen Free

Simplified Application Circuit

VPVCC

 

PVCC

 

VCC/ISEN1

VIN

 

 

 

RTON

 

 

 

BOOT1

 

 

 

 

 

 

 

 

 

VIN

TON

RT8813C

 

RSEN1

V

 

 

 

 

 

 

UGATE1

 

 

OUT

PGOOD

 

PGOOD

 

PHASE1

 

 

 

PSI

 

PSI

 

 

LGATE1

 

 

 

VID

 

VID

 

 

 

 

 

 

Chip Enable

 

EN

TALERT/ISEN2

 

 

 

 

 

VIN

 

 

 

 

 

 

 

BOOT2

 

 

 

 

SS

 

 

 

RSEN2

 

 

 

 

 

UGATE2

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

PHASE2

 

 

 

 

 

 

 

 

LGATE2

 

 

 

 

 

TSEN/ISEN3

RGND

 

 

VGND_SNS

 

 

VSNS

 

 

VOUT_SNS

 

RSET3

 

 

 

Driver

 

 

 

 

 

 

 

 

 

 

PWM3

PWM

PHASE

 

 

 

 

 

 

 

 

 

 

 

GND

 

GND

VCC

VPVCC

Copyright ©2013 Richtek Technology Corporation. All rights reserved.

is a registered trademark of Richtek Technology Corporation.

DS8813C-02 December 2013

www.richtek.com

 

1

RT8813C

Applications

Marking Information

CPU/GPU Core Power Supply

 

 

27= : Product Code

Notebook PC Memory Power Supply

 

27=YM

YMDNN : Date Code

Chipset/RAM Power Supply

 

DNN

 

 

 

 

Generic DC/DC Power Regulator

 

 

 

Ordering Information

RT8813C

Package Type

QW : WQFN-24L 4x4 (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.

Function Pin Description

Pin Configurations

(TOP VIEW)

PHASE1 LGATE1 PWM3 PVCC LGATE2 PHASE2

 

24

23

22

21

20

19

 

BOOT1 1

 

 

 

 

18

BOOT2

UGATE1 2

 

 

 

 

17

UGATE2

EN 3

 

GND

 

16

PGOOD

PSI 4

 

 

15

VCC/ISEN1

 

 

 

 

VID 5

 

 

 

25

14

TALERT/ISEN2

REFADJ 6

 

 

 

 

13

TSNS/ISEN3

7

8

9

10

11

12

 

REFIN

VREF

TON

RGND

VSNS

SS

 

WQFN-24L 4x4

 

Pin No.

Pin Name

 

Pin Function

 

 

 

1

BOOT1

Bootstrap Supply for PWM 1. This pin powers the high-side MOSFET driver.

2

UGATE1

High-side Gate Driver of PWM 1. This pin provides the gate drive for the converter's

high-side MOSFET. Connect this pin to the Gate of high-side MOSFET.

 

 

3

EN

Enable Control Input. Active high input.

 

 

Power Saving Interface. When the voltage is pulled below 0.8V, the device will operate

4

PSI

into 1 phase DEM. When the voltage is between 1.2V to 1.8V, the device will operate

into 1 phase force CCM. When the voltage is between 2.4V to 5.5V, the device will

 

 

 

 

operate into active phase force CCM (only for 2 or 3 phase).

5

VID

Programming Output Voltage

Control Input. Refer to PWM-VID Dynamic Voltage

Control.

 

 

 

 

6

REFADJ

Reference Adjustment Output. Refer to PWM-VID Dynamic Voltage Control.

 

 

 

 

7

REFIN

External Reference Input.

 

 

 

 

8

VREF

Reference Voltage Output. This is a high precision voltage reference (2V) from VREF

pin to RGND pin.

 

 

 

 

9

TON

On-Time/Switching Frequency Adjustment Input. Connect a 100pF capacitor between

CTON and ground is optional for noise immunity enhancement.

 

 

10

RGND

Negative Remote Sense Input. Connect this pin to the ground of output load.

 

 

 

11

VSNS

Positive Remote Sense Input. Connect this pin to the positive terminal of output load.

12

SS

Soft-Start Time Setting. Connect an external capacitor to adjust soft-start time.

When the external capacitor is removed, the internal soft-start function will be chose.

 

 

13

TSNS

Temperature Sensing Input for 2/1 Phase Operation.

 

 

 

ISEN3

Phase 3 Current Sense Input for 3-Phase Operation.

 

 

 

 

 

 

 

 

 

Copyright ©2013 Richtek Technology Corporation. All rights reserved.

is a registered trademark of Richtek Technology Corporation.

www.richtek.com

DS8813C-02 December 2013

2

 

 

 

 

 

RT8813C

 

 

 

 

 

Pin No.

 

Pin Name

Pin Function

 

 

 

 

Thermal Alert. Active low open drain output for 2/1 Phase Operation.

14

 

TALERT

 

ISEN2

Phase 2 Current Sense Input for 3-Phase Operation.

 

 

 

 

 

 

 

15

 

VCC

Supply Voltage Input for 2/1 Phase Operation. (Connect to PVCC)

 

 

 

 

 

ISEN1

Phase 1 Current Sense Input for 3-Phase Operation. (Connect to PHASE1)

 

 

 

 

 

 

 

16

 

PGOOD

Power Good Indicator Output. Active high open-drain output.

 

 

 

 

 

 

 

 

 

High-side Gate Driver of PWM 2. This pin provides the gate drive for the

17

 

UGATE2

converter's high-side MOSFET. Connect this pin to the Gate of high-side

 

 

 

 

MOSFET.

18

 

BOOT2

Bootstrap Supply for of PWM 2. This pin powers the high-side MOSFET driver.

 

 

 

 

 

 

 

 

 

Switch Node for PWM2. This pin is return node of the high-side driver of PWM

19

 

PHASE2

2. Connect this pin to the Source of high-side MOSFET together with the Drain

 

 

 

 

of low-side MOSFET and the inductor.

 

 

 

 

Low-Side Gate Driver of PWM 2. This pin provides the gate drive for the

20

 

LGATE2

converter's low-side MOSFET. Connect this pin to the Gate of low-side

 

 

 

 

MOSFET.

21

 

PVCC

Supply Voltage Input. Connect this pin to a 5V bias supply. Place a high quality

 

bypass capacitor from this pin to GND.

 

 

 

 

22

 

PWM3

Third Phase PWM Control Signal Output to Driver for 3-Phase Operation. In 2/1

 

Phase Operation, this pin is high impedance.

 

 

 

 

 

 

 

 

Low-Side Gate Driver of PWM 1. This pin provides the gate drive for the

23

 

LGATE1

converter's low-side MOSFET. Connect this pin to the Gate of low-side

 

 

 

 

MOSFET.

 

 

 

 

Switch Node for PWM1. This pin is return node of the high-side driver of PWM

24

 

PHASE1

1. Connect this pin to the Source of high-side MOSFET together with the Drain

 

 

 

 

of low-side MOSFET and the inductor.

25 (Exposed Pad)

 

GND

Ground. The Exposed pad should be soldered to a large PCB and connected to

 

GND for maximum thermal dissipation.

 

 

 

 

Copyright ©2013 Richtek Technology Corporation. All rights reserved.

is a registered trademark of Richtek Technology Corporation.

DS8813C-02 December 2013

www.richtek.com

 

3

Richtek RT8813CGQW Schematic

RT8813C

Function Block Diagram

 

 

VREF

 

 

 

 

 

 

 

 

 

 

 

 

 

Reference

 

 

 

 

 

VID

 

 

 

Output Gen.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

PVCC

REFADJ

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Power On Reset

 

 

 

 

PSI

 

 

Mode Select

 

 

 

 

 

 

 

 

& Central Logic

 

 

 

 

 

 

 

 

 

 

 

 

 

 

REFIN

OV Threshold

-

 

 

 

 

 

 

PGOOD

 

 

 

 

 

 

 

 

 

Select

 

+

 

 

 

 

 

 

 

 

 

 

 

 

Control & Protection Logic

 

 

 

 

 

 

UV

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

40% REFIN

+

 

 

 

Boot-Phase

 

 

 

 

 

 

-

 

 

 

Detection 1

 

 

 

 

Soft-Start

PWM

 

 

 

Boot-Phase

 

 

 

 

& Slew Rate

CMP

 

 

 

Detection 2

 

 

SS

 

Control

 

 

 

 

 

 

 

 

 

 

+

 

TON

 

 

 

 

BOOT1

 

 

 

 

 

 

 

 

VSNS

 

 

 

-

 

 

 

 

 

UGATE1

 

 

 

 

Gen 1

 

 

 

 

RGND

 

 

 

 

 

 

 

PWM1

 

 

PHASE1

 

 

Enable

To Driver Logic

 

 

 

 

 

LGATE1

EN

 

 

 

 

 

 

 

 

Logic

To Power On Reset

 

 

 

Driver

 

 

 

 

TON

 

 

 

 

To Power On Reset

 

 

 

PWM2

Logic

 

BOOT2

 

 

Gen 2

 

 

 

 

 

 

 

UGATE2

 

 

 

 

 

 

&

 

 

 

 

 

 

VIN

 

 

 

 

 

 

 

PHASE2

TON

 

 

 

 

TON

 

 

 

 

 

Detection

 

 

 

Gen 3

 

 

 

 

LGATE2

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

VCC/

 

Phase

 

 

 

 

 

 

 

 

 

ISEN1

 

Select

 

 

 

 

 

 

 

-

PWM3

TALERT/

 

 

 

 

 

 

 

 

S/H

 

ISEN2

 

 

 

 

 

 

 

 

GM+

VB

TSNS/

+

 

 

 

 

 

Current

 

 

-

 

ISEN3

 

 

 

 

 

 

S/H

 

1V

-

 

 

 

 

 

Balance

 

GM

VB

 

 

 

 

 

 

 

 

+

Internal

 

 

 

 

 

 

S/H

GM-

ISEN3

 

 

To Protection Logic

Current

 

 

+

VB

 

OTP

To Central Logic

 

 

 

 

 

 

 

PHASE1

ZCD

 

To Driver Logic

Limit

 

 

 

 

 

 

 

 

 

 

 

 

 

Copyright ©2013 Richtek Technology Corporation. All rights reserved.

is a registered trademark of Richtek Technology Corporation.

www.richtek.com

DS8813C-02 December 2013

4

 

RT8813C

Operation

The RT8813C is a 3/2/1 phase synchronous Buck PWM controller with integrated drivers which are optimized for high performance graphic microprocessor and computer applications. The IC integrates a COT (Constant-On-Time) PWM controller with two MOSFET drivers, as well as output current monitoring and protection functions. Referring to the function block diagram of TONGenx, the synchronous UGATE driver is turned on at the beginning of each cycle. After the internal one-shot timer expires, the UGATE driver will be turned off. The pulse width of this one-shot is determined by the converter's input voltage and the output voltage to keep the frequency fairly constant over the input voltage range and output voltage. Another one-shot sets a minimum off-time.

The RT8813C also features a PWM-VID dynamic voltage control circuit driven by the pulse width modulation method. This circuit reduces the device pin count and enables a wide dynamic voltage range.

Soft-Start (SS)

For internal soft-start function, an internal current source charges an internal capacitor to build the soft-start ramp voltage. The output voltage will track the internal ramp voltage during soft-start interval. For external soft-start function, an additional capacitor connected from SS to the GND will be charged by a current source and determines the soft-start time.

PGOOD

The power good output is an open-drain architecture.

When the soft-start is finished, the PGOOD open-drain output will be high impedance.

Current Balance

The RT8813C implements internal current balance mechanism in the current loop. The RT8813C senses per phase current and compares it with the average current. If the sensed current of any particular phase is higher than average current, the on-time of this phase will be adjusted to be shorter.

Current Limit

The current limit circuit employs a unique “valley” current sensing algorithm. If the magnitude of the current sense signal at PHASE is above the current limit threshold, the PWM is not allowed to initiate a new cycle. Thus, the current to the load exceeds the average output inductor current, the output voltage falls and eventually crosses the under-voltage protection threshold, inducing IC shutdown.

Over-Voltage Protection (OVP) & Under-Voltage Protection (UVP)

The output voltage is continuously monitored for over-voltage and under-voltage protection. When the output voltage exceeds its set voltage threshold (If VREFIN 1.33V, OV = 2V, or VREFIN > 1.33V, OV = 1.5 x VREFIN), UGATE goes low and LGATE is forced high; when it is less than 40% of its set voltage, under-voltage protection is triggered and then both UGATE and LGATE gate drivers are forced low. The controller is latched until PVCC is resupplied and exceeds the POR rising threshold voltage or EN is reset.

Copyright ©2013 Richtek Technology Corporation. All rights reserved.

is a registered trademark of Richtek Technology Corporation.

DS8813C-02 December 2013

www.richtek.com

 

5

RT8813C

Absolute Maximum Ratings

(Note 1)

 

 

 

 

 

TONtoGND ------------------------------------------------------------------------------------------------------------------

 

 

 

 

−0.3V to 30V

RGNDtoGND ---------------------------------------------------------------------------------------------------------------

 

 

 

 

−0.7V to 0.7V

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

 

 

 

 

−0.3V to 6V

PHASEx to GND

 

 

 

 

 

 

 

DC ------------------------------------------------------------------------------------------------------------------------------

 

 

 

 

−0.3V to 30V

<20ns -------------------------------------------------------------------------------------------------------------------------

 

 

 

 

−8V to 36V

UGATEx to PHASEx

 

 

 

 

 

 

 

DC ------------------------------------------------------------------------------------------------------------------------------

 

 

 

 

−0.3V to 6V

<20ns -------------------------------------------------------------------------------------------------------------------------

 

 

 

 

−5V to 7.5V

LGATEx to GND

 

 

 

 

 

 

 

DC ------------------------------------------------------------------------------------------------------------------------------

 

 

 

 

−0.3V to 6V

<20ns -------------------------------------------------------------------------------------------------------------------------

 

 

 

 

−2.5V to 7.5V

Other Pins--------------------------------------------------------------------------------------------------------------------

 

 

 

 

−0.3V to 6V

Power Dissipation, PD @ TA = 25°C

 

 

 

 

 

 

WQFN-24L 4x4 -------------------------------------------------------------------------------------------------------------

 

 

 

 

3.57W

 

Package Thermal Resistance

(Note 2)

 

 

 

 

 

 

WQFN-24L 4x4, θJA --------------------------------------------------------------------------------------------------------

 

 

 

 

28°C/W

 

WQFN-24L 4x4, θJC -------------------------------------------------------------------------------------------------------

 

 

 

 

7°C/W

 

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

 

 

 

260°C

 

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

 

 

 

 

150°C

 

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

 

 

 

 

−65°C to 150°C

ESD Susceptibility (Note 3)

 

 

 

 

 

 

 

HBM (Human Body Model) -----------------------------------------------------------------------------------------------

 

 

 

 

2kV

 

Recommended Operating Conditions (Note 4)

 

 

 

 

 

Input Voltage, VIN -----------------------------------------------------------------------------------------------------------

 

 

 

 

7V to 26V

Supply Voltage, VPVCC ----------------------------------------------------------------------------------------------------

 

 

 

 

4.5V to 5.5V

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

 

 

 

 

−40°C to 125°C

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

 

 

 

 

−40°C to 85°C

Electrical Characteristics

 

 

 

 

 

 

(TA = 25°C unless otherwise specified)

 

 

 

 

 

 

Parameter

Symbol

Test Conditions

Min

Typ

Max

 

Unit

PWM Controller

 

 

 

 

 

 

 

PVCC Supply Voltage

VPVCC

 

4.5

--

5.5

 

V

PVCC Supply Current

ISUPPLY

EN = 3.3V, Not Switching

--

1.5

2

 

mA

PVCC Shutdown Current

ISHDN

EN = 0V

--

--

10

 

A

PVCC POR Threshold

 

 

3.8

4.1

4.4

 

V

 

 

 

 

 

 

 

 

POR Hysteresis

 

 

--

0.3

--

 

V

 

 

 

 

 

 

 

 

Copyright ©2013 Richtek Technology Corporation. All rights reserved.

is a registered trademark of Richtek Technology Corporation.

www.richtek.com

DS8813C-02 December 2013

6

 

RT8813C

Parameter

Symbol

Test Conditions

Min

Typ

Max

Unit

Switching Frequency

fSW

RTON = 500k (Note 5)

270

300

330

kHz

Minimum On-Time

 

tON(MIN)

 

--

70

--

ns

Minimum Off-Time

 

tOFF(MIN)

 

--

300

--

ns

EN Threshold

 

 

 

 

 

 

 

EN Input Voltage

Logic-High

VENH

 

1.6

--

--

V

Logic-Low

VENL

 

--

--

0.8

V

 

 

Mode Decision

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

PSI High Threshold

VPSIH

Enables Two Phases with FCCM

2.4

--

--

V

PSI Intermediate Threshold

VPSIM

Enables One Phases with FCCM

1.2

--

1.8

V

PSI Low Threshold

VPSIL

Enables One Phases with DEM

--

--

0.8

V

VID Input Voltage

Logic-High

VVIDH

 

2

--

--

V

Logic-Low

VVIDL

 

--

--

1

V

Protection Function

 

 

 

 

 

 

Zero Current Crossing

 

 

8

--

8

mV

Threshold

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Current Limit Setting Current

IOCSET

 

9

10

11

A

Current Limit Setting Current

IOCSET_TC

 

--

6300

--

ppm/ C

Temperature Coefficient

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Current Limit Threshold

 

ROCSET = 10k

--

60

--

mV

Absolute Over-Voltage

VOVP, Absolute

VREFIN 1.33V

1.9

2

2.1

V

Protection Threshold

Relative Over-Voltage

VOVP, Relative

VREFIN > 1.33V

145

150

155

%

Protection Threshold

 

 

 

 

 

 

OV Fault Delay

 

 

FB forced above OV threshold

--

5

--

s

 

 

 

 

 

 

 

Relative Under-Voltage

VUVP

UVP

35

40

45

%

Protection Threshold

 

 

 

 

 

 

UV Fault Delay

 

 

FB forced above UV threshold

--

3

--

s

 

 

 

 

 

 

 

Thermal Shutdown Threshold

TSD

 

--

150

--

C

Minimum TM Threshold

VTSEN

(No Shutting Down)

0.98

1

1.02

V

PGOOD Blanking Time

 

From EN = high to PGOOD = high

--

2.5

--

ms

(Internal)

 

 

with VSNS within regulation point

 

 

 

 

 

 

 

 

 

From first UGATE to VSNS

 

 

 

 

VSNS Soft-Start (Internal)

 

regulation point, VREFIN = 1V and

--

0.7

--

ms

 

 

 

VSNS initial = 0V

 

 

 

 

Soft-Start Current Source

ISS

 

--

5

--

A

Error Amplifier

 

 

 

 

 

 

 

VSNS Error Comparator

 

VREFIN = 1V

17.5

12.5

7.5

mV

Threshold (Valley)

 

 

 

 

 

 

 

 

 

 

Copyright ©2013 Richtek Technology Corporation. All rights reserved.

is a registered trademark of Richtek Technology Corporation.

DS8813C-02 December 2013

www.richtek.com

 

7

RT8813C

Parameter

Symbol

Test Conditions

Min

Typ

Max

Unit

Reference

 

 

 

 

 

 

Reference Voltage

VVREF

Sourcing Current = 1mA, VID no

1.98

2

2.02

V

Switching

 

 

 

 

 

 

Driver On-Resistance

 

 

 

 

 

 

UGATE Driver Source

RUGATEsr

BOOTx PHASEx Forced to 5V

--

2

4

 

UGATE Driver Sink

RUGATEsk

BOOTx PHASEx Forced to 5V

--

1

2

 

LGATE Driver Source

RLGATEsr

LGATEx, High State

--

1.5

3

 

LGATE Driver Sink

RLGATEsk

LGATEx, Low State

--

0.7

1.5

 

Dead-Time

 

From LGATE Falling to UGATE Rising

--

30

--

ns

 

 

 

 

 

 

From UGATE Falling to LGATE Rising

--

20

--

 

 

 

 

 

 

 

 

 

 

Internal Boost Charging

RBOOT

PVCC to BOOTx, IBOOT = 10mA

--

40

80

 

Switch On-Resistance

 

 

 

 

 

 

Note 1. Stresses beyond those listed “Absolute Maximum Ratings” may cause permanent damage to the device. These are stress ratings only, and functional operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to absolute maximum rating conditions may affect device reliability.

Note 2. θJA is measured at TA = 25°C on a high effective thermal conductivity four-layer test board per JEDEC 51-7. θJC is measured at the exposed pad of the package.

Note 3. Devices are ESD sensitive. Handling precaution is recommended.

Note 4. The device is not guaranteed to function outside its operating conditions.

Note 5. Not production tested. Test condition is VIN = 8V, VOUT = 1V, IOUT = 20A using application circuit.

Copyright ©2013 Richtek Technology Corporation. All rights reserved.

is a registered trademark of Richtek Technology Corporation.

www.richtek.com

DS8813C-02 December 2013

8

 

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