Datasheet RT9224ECS Datasheet (RICHTEK)

Preliminary

RT9224E

VRM 8.5 Synchronous PWM Buck Converter

Controller and Output Voltage Monitor

General Description

The RT9224E is a high speed switching controller

designed for use in Synchronous DC/DC buck

converter for modern CPUs. The regulated output

voltage is digitally programmable from 1.05V to

1.825V by a 5-bit DAC which provides initial

accuracy of ±1%. The RT9224E drives two external

N-channel MOSFETs, providing high efficiency and

eliminating the need for high cost P-channel devices.

It senses the output current across the on-resistance

of the N-channel MOSFET and provides an

adjustable current limit without external sense

resistor.

RT9224E monitors the output voltage and provides

the output signal for power-good and over-voltage

protections. The switching frequency is 200kHz. The

high switching frequency cooperating with a high

speed error amplifier maintains a fast response to

the dynamic load of modern CPUs.

Ordering Information

RT9224E

Package type
S : SOP-20

Operating temperature range

C: Commercial standard

Features

z

Simple Voltage-mode PWM Control with Buck

Rectification

z ±

±1% DAC Output Voltage Accuracy

±±

z

5-Bit Digital-to-Analog Output Voltage Range

from 1.05V to 1.825V

z

Fast Transient Response and Excellent Output

Voltage Regulation

z

Fault Protection for Over-voltage and Over-

current

z

Power-good Output Voltage Monitor

Applications

Power Supply for VRM 8.5 Microprocessors

z

Low-voltage Distributed Power Supplies

z

High Power 5V to 1.05V ~ 1.85V Switching

z

Regulator

Pin Configurations

Part Number Pin Configurations

RT9224ECS

(Plastic SOP-20)

VSEN

OCSET

SS

VID25

VID0

VID1

VID2

VID3

NC

FB

TOP VIEW

1

2

3

4

5

6

7

8

9

10

20

19

18

17

16

15

14

13

12

11

NC

OVP
VCC

LGATE
PGND

BOOT

UGATE

PHASE

PGOOD

GND

DS9224E-01 May 2001 www.richtek-ic.com.tw

1

RT9224E

Preliminary

Absolute Maximum Ratings

z Supply Voltage +15V

z Boot Voltage +15V

z Input, Output or I/O Voltage GND – 0.3V to V

z Storage Temperature Range –65°C ~150°C

z Package Thermal Resistance

SOP-20, θ

JA

87°C/W

+ 0.3V

CC

Recommended Operating Conditions

z Supply Voltage +12V±10%

z Ambient Temperature Range 0°C to 70°C

z Junction Temperature Range 0°C

to 125°C

Electrical Characteristics

(TA = 25°C, recommended operating conditions, unless otherwise specified)

Parameter Symbol Test Conditions Min Typ Max Units

VCC Supply Current

Nominal Supply

I

CC

UGATE and LGATE -- 3 -- mA

Power-on Reset

VCC Rising Threshold

VCC Falling Threshold

Rising V

OCSET

Threshold

V

OCSET

V

OCSET

= 4.5V

= 4.5V

-- 9.5 -- V

-- 7.5 -- V

-- 1.6 -- V

Oscillator

Free Running Frequency 170 200 230 KHz

Ramp Amplitude

∆V

OSC

-- 1.9 -- V

P-P

Reference and DAC

DAC (VID0-VID25) Input Low Voltage -- -- 0.8 V

DAC (VID0-VID25) Input High Voltage 2.0 -- -- V

DACOUT Voltage Accuracy -1.0 -- +1.0 %

Error Amplifier

DC Gain -- 65 -- dB

Gate Drivers

UGATE Source

UGATE Sink

LGATE Source

LGATE Sink

R

UGATEVBOOT

R

UGATEVUGATE

I

LGATE

R

LGATEVLGATE

VCC = 12V, VLGATE = 6V

– V

– V

= 1V

PHASE

PHASE

= 12V

= 1V

-- 8 --

-- 5 --

-- 500 --

-- 5 --

Ω

Ω

mA

Ω

To be continued

www.richtek-ic.com.tw DS9224E-01 May 2001

2

Preliminary

RT9224E

Parameter Symbol Test Conditions Min Typ Max Units

Protection

Over-voltage Trip (VSEN/DACOUT) -- 115 120 %

OCSET Current Source

OVP Sourcing Current

Soft-Start Current

I

OCSET

I

OVP

I

SS

V

OCSET

V

SEN

V

SS

= 4.5V

= 5.5V, V

= 1.5V

OVP

= 0V

167 200 233

60 -- -- mA

-- 10 --

Power Good

Upper Threshold (VSEN/DACOUT) VSEN Rising 106 -- 114 %

Lower Threshold (VSEN/DACOUT) VSEN Falling 89 -- 96 %

Hysteresis (VSEN/DACOUT) Upper and Lower Threshold -- 2 -- %

PGOOD Voltage Low

V

PGOOD

I

CPGOOD

= -5mA

-- 0.5 -- V

Function Block Diagram

VCC

VSEN

OCSET

REFE RENCE

110%

90%

115%

200µA

+

_

+

_

OVER-

VOLTAGE

+

_

+

_

OVER-

CURRENT

4. 5V

POWER-ON

RESET (POR)

SOFT­START

PGOOD

OVP

10µA

SS

BOOT
UGATE

µA

µA

PHASE

LG ATE
PGND

GND

_

INHIBIT

GATE

CONTROL

LO GIC

PWM

VID0
VID1
VID2
VID3

VID25

FB

DS9224E-01 May 2001 www.richtek-ic.com.tw

TTL D/A

CONVERTER

(DAC)

DACO UT

ERRO R
AMP

+

OSCILLATOR

PWM

COMPARATOR

+

_

3

RT9224E

Preliminary

Pin Description

Pin No. Pin Name Pin Function

1 VSEN Output Voltage Monitoring Input for OVP and PGOOD

Over current set pin, sinks 200µA through a resistor (R
set the trip point:

×µ

RA200

2 OCSET

3SS

4 VID25 Switching regulator output voltage setting

5 VID0 Switching regulator output voltage setting

6 VID1 Switching regulator output voltage setting

7 VID2 Switching regulator output voltage setting

8 VID3 Switching regulator output voltage setting

9 NC No connection

10 FB Feedback input pin

11 GND IC signal ground

12 PGOOD

13 PHASE Current limit sense input

=

I

PEAK

An over-current trip cycles the soft-start function

Soft start speed is set by internal 10µA current source and capacitor from this pin to GND

Open drain logic output
This pin is pulled low when the converter output is not within ±10% of the DACOUT
reference voltage

OCS

−

cetanresisonMOSFET

) from this upper N-MOSFET to

OCS

14 UGATE High side driver output

15 BOOT Driver power

16 PGND Low-side driver GND

17 LGATE Low side driver output

18 VCC Power supply input

Over voltage protection

19 OVP

20 NC No connection

This pin is pulled high when the VSEN voltage is over 15% of the DACOUT reference
voltage

www.richtek-ic.com.tw DS9224E-01 May 2001

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Preliminary

Table 1 Output Voltage Program

RT9224E

Pin Name

VID25 VID3 VID2 VID1 VID0

00100 1.050V

10100 1.075V

00011 1.100V

10011 1.125V

00010 1.150V

10010 1.175V

00001 1.200V

10001 1.225V

00000 1.250V

10000 1.275V

01111 1.300V

11111 1.325V

01110 1.350V

11110 1.375V

01101 1.400V

11101 1.425V

01100 1.450V

Nominal Output Voltage DACOUT

11100 1.475V

01011 1.500V

11011 1.525V

01010 1.550V

11010 1.575V

01001 1.600V

11001 1.625V

01000 1.650V

11000 1.675V

00111 1.700V

10111 1.725V

00110 1.750V

10110 1.775V

00101 1.800V

10101 1.825V

Note: (1) 0:Connected to GND (2) 1:Open

DS9224E-01 May 2001 www.richtek-ic.com.tw

5

RT9224E

Typical Application Circuit

L1

VIN = 5V

F1

1µHC

IN

+

5×1000µF

Preliminary

2N6394

2×1µF

+12V

0.1µF

10

0.1µF

VSEN

RT

VID25
VID0

VID1
VID2

VID3

SS

Ω

15V

19

_

_

+

FB

10

3

1

20

4

5

6
7
8

18

MONI TOR AND

PROTECTION

OSC

D/A

+

2K

1000 pF

OVPVCC

11

OCSET

2

12

15

14

13

17

16

GND

PGOOD

BOOT

UGATE

PHASE

LGATE

PGND

1K

D2

Q2

Q1

L2 - 3µH

C

OUT

9×1000µF

4.99K

0.68µF

750K

+V

O

+

Component Selection Notes:

C

, C

– Each 1000µF 6.3WV DC, Sanyo MV-GX or Equivalent.

IN

OUT

L2 – Core: Micrometals T50-52B; Winding: 10 Turns of 16AWG.

L1 – Core: Micrometals T50-52; Winding: 5 Turns of 18AWG.

D2 – 3A, 40V Schottky, Motorola MBR340 or Equivalent.

Q1, Q2 – PHB83N03LT; PHB95N03LT

www.richtek-ic.com.tw DS9224E-01 May 2001

6

Package Information

Preliminary

RT9224E

H

M

B

A

C

FD

Dimensions In Millimeters Dimensions In Inches

Symbol

Min Max Min Max

A 12.598 13.005 0.496 0.512

B 7.391 7.595 0.291 0.299

C 2.362 2.642 0.093 0.104

D 0.330 0.508 0.013 0.020

I

B

J

F 1.194 1.346 0.047 0.053

H 0.229 0.330 0.009 0.013

I 0.102 0.305 0.004 0.012

J 10.008 10.643 0.394 0.419

M 0.381 1.270

0.015 0.050

DS9224E-01 May 2001 www.richtek-ic.com.tw

7

RT9224E

Preliminary

RICHTEK TECHNOLOGY CORP.

Headquarter

6F, No. 35, Hsintai Road, Chupei City

Hsinchu, Taiwan, R.O.C.

Tel: [phone] Fax: [phone]

www.richtek-ic.com.tw DS9224E-01 May 2001

RICHTEK TECHNOLOGY CORP.

Taipei Office (Marketing)

8F-1, No. 137, Lane 235, Paochiao Road, Hsintien City

Taipei County, Taiwan, R.O.C.

Tel: [phone] Fax: [phone]

Email: [e-mail]

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