IRU3034 & (PbF)

6

www.irf.com

Figure 4 - The circuit in figure 4 is the application of the IRU3034 which is done using a dual layout with IRU3033 in

a switching mode only. This circuit can be used to generate a low cost 5V to 3.3V for either Pentium application

with AGP socket or in Pentium II applications where it is desirable to generate an accurate on-board 3.3V supply.

TYPICAL APPLICATION

5V to 3.3V for Pentium Application with AGP or Pentium II Application without ATX power supply

Switching mode Operation. (IRU3034 and IRU3033 Dual Layout)

Ref Desig

Description

Qty

Part #

Manuf

U1

LDO/Switcher IC

1

IRU3034CS (8-Pin SOIC)

IR

Q2

MOSFET

1

IRL3303 (TO-220)

IR

IRL3103S (TO-263) (Note 1)

D1

Schottky Diode

1

MBR1045CT (TO-220)

MBRB1545CT (TO-263) (Note1)

Motorola

L2

Inductor

1

Core: T50-18, L=4µH

Micro Metal

Turns: 10T, 18 AWG

(core)

L1

Inductor

1

L=2µH

R1

Resistor

1

22Ω, 5%, SMT 1206 size

R9

Resistor

1

Open for IRU3034, 10Ω for IRU3033

R2

Resistor

1

10Ω, 5%, SMT 1206 size

R3

Resistor

1

249KΩ, 1%, SMT 0805 size

R4

Resistor

1

1KΩ, 1%, SMT 0805 size

R5

Resistor

1

576Ω, 1%, SMT 0805 size

R6

Resistor

1

5mΩ, 5%, 2W

R7

Resistor

1

4.99KΩ, 1%, SMT 0805 size

R8

Resistor

1

4.7KΩ, 5% for IRU3034, Open for IRU3033

C1, 2

Capacitor

2

6MV1500GX, 1500µF, 6.3V, Elect

Sanyo

C3

Capacitor

1

1µF, Ceramic, SMT 0805 size

C4

Capacitor

1

470pF, Ceramic, SMT 0805 size

Sanyo

C5

Capacitor

1

10pF, Ceramic, SMT 0805 size

Sanyo

C6

Capacitor

1

4700pF for IRU3034, Open for IRU3033

C7

Capacitor

2

6MV1500GX, 1500µF, 6.3V, Elect

Sanyo

C8

Capacitor

1

0.047µF for IRU3034 , 0.1µF for 3033

HS1

Heat Sink

1

For MOSFET, 577002

Aavid

HS2

Heat Sink

1

For Schottky Diode, 577002

Aavid

Note: For the applications where it is desirable to eliminate the heat sink, the IRL3103S for Q2 and MBR1545CT

for D2 in TO-263 packages with minimum of 1" square copper pad can be used.

5V

C1

L1

C3

Q2

C2

L2

R4

C7

D1

R2

C4

R5

R1

R3

C5

R8

R6

C6

R7

12V

C8

R9

Drv

Gnd

CS-/

CS+/

Drv2

SS/

U1