an8015sh Panasonic Corporation of North America, an8015sh Datasheet - Page 12

• Manufacturer Part Number: an8015sh
• Description: Single-channel Step-down, Step-up, Or Inverting Use Dc-dc Converter Control Ic
• Manufacturer: Panasonic Corporation of North America

AN8015SH
12
[5] Time constant setting method for short-circuit protection circuit with joint-use of soft start/timer latch type
output drive transistor by enabling the low input voltage malfunction prevention circuit, and sets the dead-time at 100%.
approximately 30 mV but the latch circuit is not reset unless the power is turned off.
on. However, since at the beginning of power on, the error amplifier output is high level, and V
voltage is released and charging begins; the external capacitor should be set so that the output voltage of DC-DC
convertor starts to rise before the latching circuit is set. The charging equation is as same as the above. The soft start
time t
Application Notes (continued)
(continued)
When the external capacitor C
The low input voltage malfunction prevention circuit is once enabled, the S.C.P. terminal voltage is discharged to
The S.C.P. terminal voltage is inputted to the PWM comparator, and the soft start is actuated when the power turns
1.25 V
t
SS
IN
IN
SS
FB
until the input standby voltage V
1.22
8
9
10
0.03 V
Error amp.
I
CHG
C
S
I
[s]
CHG
S.C.P. comp.
t
C
SS
S
1.83 V
S
has been charged up to approximately 1.83 V, it sets the latch circuit, cuts off the
1.25 V
Figure 6. Short-circuit protection circuit
STBY
Q1
becomes 1.25 V is given in the following equations:
Clamp
circuit
I
CHG
C
Q2
S
Latch
S R
U.V.L.O.
R
Voltage Regulators
PWM comparator input
PE
of S.C.P. terminal
Output cut-off
V
REF