US3034
TYPICAL APPLICATION
5V to 3.3V with lossles short cicuit protection(output UVLO detection).
C8
8
7 6 5
R7
SS CS+ CS- Gnd
US3034
Drv V12 Vfb Vhyst
C6
R6
1
2
3
4
12V
5V
C3
R3
C5
L2
R1
Vout
C7
L1
C4
Q2
R4
R5
C1
C2
R2
D1
3034app5-1.1
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.
Ref Desig Description
Qty
1
1
Part #
Manufacturer
Unisem
International
Rectifier
U1
Q2
Switcher IC
MOSFET
US3034CS ( 8 pin SOIC)
IRL3303 (TO263)
D1
L2
Schottky Diode
Inductor
1
1
PBYR735(Axial Thr Hole pkg)
PBYR1035B(SMT, TO263 pkg)
Core:T50-18,L=4 uH
Turns: 7T, 18 AWG
L=1 uH
10 ohm,5%, SMT
182 kohm,1%, SMT
1 kohm,1%, SMT
576ohm,1%, SMT
3.83 kohm,1%, SMT
1 kohm,1% , SMT
470uF, Elect
6MV1000GX, 1000uF,6.3V, Elect
1 uF,Ceramic, SMT
10 pF,Ceramic, SMT
0.1 uF
Motorola
Micro Metal
(core)
L1
Inductor
1
2
1
1
1
1
1
1
1
1
1
1
2
1
R1,2
R3
R4
R5
R7
R6
C1
C2
C3
C5
C6
C7
C8
Resistor
Resistor
Resistor
Resistor
Resistor
Resistor
Capacitor
Capacitor
Capacitor
Capacitor
Capacitor
Capacitor
Capacitor
Sanyo
Sanyo
Sanyo
6MV1000GX, 1000uF,6.3V, Elect
0.047 uF
Rev. 1.8
1/13/99
4-7
UNISEM [ UNISEM ]
