Richtek RT8813AGQW Schematic [ru]

RT8813A

Multi-Phase PWM Controller with PWM-VID Reference

General Description

The RT8813A 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 RT8813A adopts R

Current limit is accomplished through continuous inductor-

current-sense, while R

accurate channel current balance. Using the method of

current sampling utilizes the best advantages of each

technique.

The RT8813A features external reference input and PWM-

VID 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.

current sensing technique.

DS(ON)

current sensing is used for

DS(ON)

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 R



 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



Current Sensing for Current Balance

DS(ON)

Simplified Application Circuit

VCC/ISEN1

BOOT1

RT8813A

UGATE1

PHASE1

LGATE1

TALERT/ISEN2

BOOT2

UGATE2

PHASE2

LGATE2

RGND

VSNS

PWM3

GND

SEN1

SEN2

Driver

PWM PHASE

GND

VCC

GND_SNS

OUT_SNS

OUT

PVCC

SET3

PVCC

TON

PGOOD

PSI

VID

TSEN/ISEN3

PVCC

TON

PGOOD

PSI

VID

Chip Enable

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RT8813A

Applications

 CPU/GPU Core Power Supply

 Notebook PC Memory Power Supply

 Chipset/RAM Power Supply

 Generic DC/DC Power Regulator

Ordering Information

RT8813A

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 require-

ments of IPC/JEDEC J-STD-020.

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

Function Pin Description

Marking Information

0P= : Product Code

0P=YM

YMDNN : Date Code

DNN

Pin Configurations

(TOP VIEW)

PVCC

LGATE1

PWM3

LGATE2

21 20 1924 2223

GND

TON

VREF

VSNS

RGND

WQFN-24L 4x4

BOOT1

UGATE1

EN PSI VID

REFADJ

PHASE1

78910 1211

REFIN

PHASE2

BOOT2

UGATE2

PGOOD

VCC/ISEN1

TALERT/ISEN2

TSNS/ISEN3

Pin No. Pin Name Pin Function

1 BOOT1 Bootstrap Suppl y for PWM 1. This pin powers the high side MOSFE T driver.

2 UGATE1

High Side Gate Driver of PWM 1. This pin prov ides the gate drive for the converter's high side MOSFET. Connect this pin to the Gate of high s ide MOSFET.

3 EN Enable Contro l I nput. Active hig h 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 bet ween 1.2V to 1.8V, the dev ice will operate into 1 phase f orce CCM. W hen t he 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 Contr ol Input. Ref er to PWM-VID Dynamic Voltage Control .

6 REFADJ Refere nce Ad justment Output. Refer t o PWM-VID Dynamic Voltage Contro l.

7 REF IN External Reference Input.

8 VREF

9 TON

Refere nce Voltage Output. This is a high precision voltage refere nce (2V ) from VREF pin to RGND pi n.

On-Time/ Switching Freq uency Adjustment Input. Connect a 100pF capacito r between C

and gr ound is optional for noise imm unity enhancem ent.

TON

10 RGND Negative Remote Sense Input. Connect this pin to the ground of output lo ad.

11 V SNS Positive Remote Sense Input. Connect t his pin to the positive terminal of output load.

12 SS

Soft-Start Time Sett in g. Connect an ext erna l capacitor to adjust soft -start time. When the ex ternal capacitor is remove d, t he i nt ernal soft-start function will be chose.

TSNS Temperatu re Sensing Inp ut f or 2/1 Phase Operati on.

ISEN3 Phase 3 Current Sense Inp ut f or 3 Phase Operation.

DS8813A-05 December 2013www.richtek.com

Pin No. Pin Name Pin Function

RT8813A

16 PGOOD Power Good Indicator Output. Active high open drain output.

17 UGATE2

18 BOOT2 Bootstrap Supply for of PWM 2. This pin powers the high side MOSFET driver.

19 PHASE2

20 LG ATE2

21 PVCC

22 PW M 3

23 LG ATE1

24 PHASE1

25 (Exposed Pad) GND

TALERT

ISEN2 Phase 2 Current Sense Input for 3 Phase Operation.

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)

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

High Side Gate Driver of PWM 2. This pin provides the gate drive for the converter's high side MOSFET. Connect this pin to the Gate of high side MOS FET.

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

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

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

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

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

1. Connect this pin to the Source of high side MOSFET together with the Drain of low side MOSFET and the inductor.

Ground. The Exposed pad should be soldered to a large PCB and connected to GND for maximum thermal dissipation.

DS8813A-05 December 2013 www.richtek.com

RT8813A

Function Block Diagram

VREF

VID

REFADJ

PSI

REFIN

OV Threshold

Select

40% REFIN

Mode Select

Reference

Output Gen.

Power On Reset

& Central Logic

Control & Protection Logic

Boot-Phase Detection 1

PVCC

PGOOD

VSNS

RGND

TON

VCC/

ISEN1

TALERT/

ISEN2

TSNS/ ISEN3

Soft-Start

& Slew Rate

Control

Enable

Logic

To Power On Reset

VIN

Detection

Phase Select

Internal

OTP

To Central Logic

PWM

CMP

To Driver Logic To Power On Reset

To Protection Logic

ZCDPHASE1

TON

Gen 1

TON

Gen 2

TON

Gen 3

To Driver Logic

Current

Balance

Current

Limit

Boot-Phase Detection 2

PWM1

Driver

Logic

PWM2

S/H

ISEN3

BOOT1 UGATE1 PHASE1

LGATE1

BOOT2 UGATE2

PHASE2

LGATE2

PWM3

DS8813A-05 December 2013www.richtek.com

Operation

RT8813A

The RT8813A 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 TON Genx, 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 RT8813A 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.

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 V

OV = 2V, or V

> 1.33V, OV = 1.5 x V

REFIN

≤ 1.33V,

), 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 re-supplied

and exceeds the POR rising threshold voltage or EN is

reset.

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 RT8813A implements internal current balance

mechanism in the current loop. The RT8813A 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.

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RT8813A

Absolute Maximum Ratings (Note 1)

 TON to GND ------------------------------------------------------------------------------------------------------------------ −0.3V to 30V

 RGND to GND --------------------------------------------------------------------------------------------------------------- −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, P

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

@ T

= 25°C

Recommended Operating Conditions (Note 4)

 Input Voltage, V

 Supply Voltage, V

 Junction Temperature Range --------------------------------------------------------------------------------------------- −40°C to 125°C

 Ambient Temperature Range --------------------------------------------------------------------------------------------- −40°C to 85°C

----------------------------------------------------------------------------------------------------------- 7V to 26V

---------------------------------------------------------------------------------------------------- 4.5V to 5.5V

PVCC

Electrical Characteristics

= 25°C unless otherwise specified)

Parameter Symbol Test Conditions Min Typ Max Unit

PWM Controller

PVCC Supply Voltage V

PVCC Supply Current I

PVCC Shutdown Current I

PVCC POR Threshold 3.8 4.1 4.4 V

POR Hysteresis -- 0.3 -- V

4.5 -- 5.5 V

PVCC

SUPPLY

SHDN

EN = 3.3V, Not Switching -- 1.5 2 mA

EN = 0V -- -- 10 A

DS8813A-05 December 2013www.richtek.com

Parameter Symbol Test Conditions Min Typ Max Unit

Switching Frequ ency fSW R

Minimum On-Time t

Minimum Off-Time t

ON(MIN)

OFF(MI N)

-- 70 -- ns

= 500k (Note 5) 270 300 330 k Hz

TON

-- 300 -- ns

EN Threshold

RT8813A

EN Input Voltage

Logic-High V

Logic-Low V

1.6 -- -- V

ENH

-- -- 0.8 V

ENL

Mode Decision

PSI High Threshold V

PSI In termediate Thr eshold V

PSI Low Threshold V

Logic-High V

VID Input Voltage

Logic-Low V

Enables Two Phases with FCCM 2.4 -- -- V

PSIH

Enables One Phases with FCCM 1.2 -- 1.8 V

PSIM

Enables One Phases with DEM -- -- 0.8 V

PSIL

2 -- -- V

VIDH

-- -- 1 V

VIDL

Protection Function

Zero Current Crossing Threshold

Current Limit Setting Current I

Current Limit Setting Current Temperature Coef ficient

8 -- 8 mV

9 10 11 A

OCSET

OCSET_TC

-- 6300 -- ppm/C

Current Limit Threshold R

Absolute Over Voltage Prote ction Threshold

Relative Over Voltage Prote ction Threshold

OVP, Absolute

OVP, Relative VRE FIN

= 10k -- 60 -- mV

OCSET

 1.33V 1.9 2 2.1 V

RE FIN

> 1.33V 145 150 155 %

OV Fault Delay FB forced above OV th resh old -- 5 -- s

Relative Under Voltage Prote ction Threshold

UVP 35 40 45 %

UVP

UV Fault Delay FB forced above UV threshol d -- 3 -- s

Thermal Shutdown Th reshold TSD -- 150 -- C

Minim um TM Threshold V

PGOOD Blanking Time (Interna l)

(No Shutting Do wn) 0.98 1 1.02 V

TSEN

From EN = high to PGOOD = high with VSNS withi n regulation poin t

-- 2.5 -- ms

From first UGATE to VSNS

VSNS Soft-Start (Internal)

regulation point, V

RE FIN

= 1V and

-- 0.7 -- ms

VSNS initial = 0 V

Soft-Start Current Source ISS -- 5 -- A

Er ror Amp l if ier

VSNS Error Comparator Threshold (Valley)

= 1V 17.5 12.5 7.5 mV

RE FIN

DS8813A-05 December 2013 www.richtek.com

RT8813A

Parameter Symbol Test Conditions Min Typ Max Unit

Refer ence

Reference Voltage V

Driver On-Resi s tance

VREF

Sourcing Current = 1mA, VID no Switching

1.98 2 2.02 V

UGATE Driver Source R

UGATE Driver Sink R

LGATE Driver Source R

LGATE Driver Sink R

UGATEsr

UGATEsk

LGATEsr

LGATEsk

BOOT x  PHASEx Forced to 5V -- 2 4 

BOOT x  PHASEx Forced to 5V -- 1 2 

LGATEx, High State -- 1.5 3 

LGATEx, Low State -- 0.7 1.5 

From LGATE Falling to UGATE Rising -- 30 --

Dead-Time

From UGATE Falling to LGATE Rising -- 20 --

Internal Boost Charging 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. θ

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 V

is measured at T

measured at the exposed pad of the package.

PVCC to BOOTx, I

BOOT

= 25°C on a high effective thermal conductivity four-layer test board per JEDEC 51-7. θJC is

= 8V, V

OUT

= 1V, I

= 10mA -- 40 80 

BOOT

= 20A using application circuit.

OUT

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Richtek RT8813AGQW Schematic [ru]

Specifications and Main Features

Frequently Asked Questions

User Manual