MB3882 Fujitsu Media Devices, MB3882 Datasheet - Page 15

• Manufacturer Part Number: MB3882
• Description: 2-channel DC/DC Converter IC with Synchronous Rectifier
• Manufacturer: Fujitsu Media Devices

SETTING THE TIMER LATCH SHORT CIRCUIT PROTECTOR TIME CONSTANT
Each channel has a short circuit protection comparator (SCP Comp.) which constantly compares the error Amp.
output level to the reference voltage.
When the DC/DC comparator load conditions are stable on all channels, the short circuit protection comparator
output is at “H” level, transistor Q1 is on, and the CSCP terminal (pin 22) is held at input standby voltage
If load conditions change rapidly, such as during a load short, causing output voltage to drop, the short circuit
protection comparator output goes to “L” level. This causes the transistor Q1 to shut off, charging the short circuit
protection capacitor Cscp (connected to the CSCP terminal) at 1 A.
When the capacitor Cscp is charted to the threshold voltage (V
FET off (setting the idle interval to 100 ) . At this time the latch input is closed and the CSCP terminal is held
at the input latch voltage (V
channels are shut off.)
(V
Short detection time
tscp (s) : = 0.68
STB
:
50 mV) .
Cscp ( F)
I
:
50 mV) . (When a short circuit is detected on either of the two channels, both
TH
:
0.68 V) a latch is set, turning the external
MB3882
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