CS51033
CS51033
Fast PFET Buck Controller
Does Not Require Compensation
Description
The CS51033 is a switching con-
troller for use in DC-DC converters.
It can be used in the buck topology
with a minimum number of exter-
nal components. The CS51033 con-
sists of a 1.0A power driver for con-
trolling the gate of a discrete P-
channel transistor, fixed frequency
oscillator, short circuit protection
timer, programmable soft start, pre-
cision reference, fast output voltage
monitoring comparator, and output
stage driver logic with latch.
The high frequency oscillator
allows the use of small inductors
and output capacitors, minimizing
PC board area and systems cost.
The programmable soft start
reduces current surges at start up.
The short circuit protection timer
significantly reduces the PFET duty
cycle to approximately 1/30 of its
normal cycle during short circuit
conditions.
The CS51033 is available in 8L SO
and 8L PDIP plastic packages.
Features
s
1A Totem Pole Output
Driver
s
High Speed Oscillator
(700kHz max)
s
No Stability
Compensation Required
s
Lossless Short Circuit
Protection
s
2% Precision Reference
s
Programmable Soft Start
Typical Application Diagram
3.3V
IN
D
2
1N4148
C
IN
100µF
R
C
10Ω
D
4
1N5818
D
3
1N4148
C
1
0.1µF
Package Options
8 Lead SO Narrow & PDIP
V
GATE
1
V
C
CS
V
CC
V
FB
V
C
V
CC
V
GATE
U1
CS51033
C
OSC
V
FB
R
G
10Ω
IRF 7404
0.01µF
4.7µH
100
1.5V
OUT
@3Amp
.1µF
D
1
1N5821
PGnd
C
OSC
Gnd
C
2
1µF
C
3
100µF
C
OSC
150pF
Gnd
PGnd
CS
CS
0.1µF
C
0
100µF
C
4
0.1µF
100µF
Gnd
R
A
1.5k
NOTE:
Capacitors C
2
, C
3
and C
4
are low ESR tantalum
caps used for noise reduction.
R
B
300
Gnd
Cherry Semiconductor Corporation
2000 South County Trail, East Greenwich, RI 02818
Tel: (401)885-3600 Fax: (401)885-5786
Email: info@cherry-semi.com
Web Site: www.cherry-semi.com
Rev. 2/13/98
1
A
®
Company
CHERRY [ CHERRY SEMICONDUCTOR CORPORATION ]
