SS6578 ETC-unknow, SS6578 Datasheet - Page 9

• Manufacturer Part Number: SS6578
• Description: High Efficiency Step Down Dc/dc Controller
• Manufacturer: ETC-unknow

Rev.2.02 4/06/2004
B. Short Circuit Protection Design
1. As
2. Design1: shown as Fig. 12.
(abbreviated as SCP) does not always exist in
the DC-DC converter circuit. The fact is usually
the DC-DC converter provides the circuits
attached to VOUT with low power or low
voltage. Sometimes there is less concern about
safety, as the probability of short-circuit is
quite low. That gives users reasons to ignore
the use of an SCP circuit. However, we would still
like to point out the importance of the
protection. With SCP, the system will be well
protected in any situation. Two SCP circuits
are introduced as follows for your reference.
we
+V
Method: Add a fast fuse to V
IN
= 5~18V
know,
*
*** R6 can adjust the duty cycle max. It can be 0
V
V
Short
+
100 F
IN
IN
LL4148
Rs
C1
>15V, R7=15
D2
1 F
15V, R7=0 *
C3
Fig 11. DC/DC Buck Converter V
Circuit
100K
R2
Q2
www.SiliconStandard.com
R1
3K3
Protection
OUT
Q1
SSM4435
C2
0.1uF
.
***
1M
<15V
R6
D1
SS32
1
2
3
4
VIN
DUTY
SHDN
FB
U1 SS6578
3. Design 2: shown as Fig. 13.
L1 33 H
OUT
GND
DRI
CS- 7
CS+ 8
=3.3V
6
5
A fuse can be selected to pass
the start up current, but open quickly
with a large unexpected current. Of
course,
is needed after short circuit.
Method: Add a SCP circuit
Note: 1. The time constant, which is
R7
*
470 F
2. Circuit can be recovered by
3. The condition for applying
C4
replacement
directly related to R1 and C1,
has a serious effect on the
circuit.
removing the short circuit
event from the system.
this design is V
+V
+
OUT
27K
R4
, 3.3V
R3
47K
of
OUT
the
3V.
fuse
SS6578
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