US3034

4-7

Rev. 1.8

1/13/99

Figure 5- The circuit in figure 5 is designed to provide lossles output short detection by detecting the dc voltage across the inductor

and shutting down the MOSFET and entering HICCUP mode. Note that the current limit point is a function of the inductor resistance

and in this application with approximately 8 mil ohm resistance the peak C.L is set at 10A. See application note on how to set the

current limiting threshold.

TYPICAL APPLICATION

TYPICAL APPLICATION

5V to 3.3V with lossles short cicuit protection(output UVLO detection).

Ref Desig

Description

Qty

Part #

Manufacturer

U1

Switcher IC

1

US3034CS ( 8 pin SOIC)

Unisem

Q2

MOSFET

1

IRL3303 (TO263)

International

Rectifier

D1

Schottky Diode

1

PBYR735(Axial Thr Hole pkg)

PBYR1035B(SMT, TO263 pkg)

Motorola

L2

Inductor

1

Core:T50-18,L=4 uH

Micro Metal

Turns: 7T, 18 AWG

(core)

L1

Inductor

1

L=1 uH

R1,2

Resistor

2

10 ohm,5%, SMT

R3

Resistor

1

182 kohm,1%, SMT

R4

Resistor

1

1 kohm,1%, SMT

R5

Resistor

1

576ohm,1%, SMT

R7

Resistor

1

3.83 kohm,1%, SMT

R6

Resistor

1

1 kohm,1% , SMT

C1

Capacitor

1

470uF, Elect

C2

Capacitor

1

6MV1000GX, 1000uF,6.3V, Elect

Sanyo

C3

Capacitor

1

1 uF,Ceramic, SMT

C5

Capacitor

1

10 pF,Ceramic, SMT

Sanyo

C6

Capacitor

1

0.1 uF

C7

Capacitor

2

6MV1000GX, 1000uF,6.3V, Elect

Sanyo

C8

Capacitor

1

0.047 uF

3034app5-1.1

Vout

5V

C1

L1

C3

Q2

C2

L2

R4

C7

D1

R2

C4

R5

R1

12V

R3

C5

C8

1

2

3

4

5

6

7

8

Drv V12 Vfb Vhyst

Gnd

CS-

CS+

SS

US3034

R6

C6

R7