an8011s Panasonic Corporation of North America, an8011s Datasheet - Page 12

• Manufacturer Part Number: an8011s
• Description: 2-channel Step-down, Step-up, Or Inverting Use Dc-dc Converter Control Ic
• Manufacturer: Panasonic Corporation of North America

AN8011S
12
[3] The time constant setting method for timer latch type short-circuit protection circuit (continued)
[4] Explanation of unlatch protection circuit operation
output becomes high-level, then SW1 becomes on state and the charging starts. It is necessary to set the external
capacitor so as to start up the DC-DC converter output voltage before setting the latch circuit in the later stage.
amplifier output terminal of the channel, to low by setting DTC terminal to 0.12 V or less through external signal.
Consequently, by controlling the DTC terminal voltage, it is possible to operate only one channel, or to start and stop
each channel in any required sequence.
Application Notes (continued)
FB2
FB1
When the power supply is turned on, the output is considered to be short-circuited state, so that the error amplifier
Especially, pay attention to the delay of the start-up time when applying the soft-start.
Figure 4 shows the block diagram of the unlatch protection circuit. It is possible to suppress FB terminal, the error
DTC1
IN 1
12
5
FB1
IN
12
14
13
11
Latch comp.
0.12 V typ.
I
1.85 V
DTC1
Error amp.1
I
80 A typ.
CHG
Unlatch protection
comp.1
Figure 4. Unlatch protection circuit
4
To PW1
SW1
10 k
typ.
30 k
typ.
Latch
C
S
4.2 k typ.
Figure 3. Short-circuit protection circuit
Unlatch protection
comp.2
1.25 V
typ.
To PW2
S
Latch
Error amp.2
R
0.12 V typ.
I
R
U.V.L.O.
DTC2
Voltage Regulators
Cut output off
5
4
6
FB2
IN 2
DTC2
V
REF