MB3825A Fujitsu Microelectronics, Inc., MB3825A Datasheet - Page 19

• Manufacturer Part Number: MB3825A
• Description: 6-ch DC/DC Converter ic With Synchronous Rectifier
• Manufacturer: Fujitsu Microelectronics, Inc.

3. Protective Functions
(1) Timer-latch short-circuit protection circuit
(2) Under voltage lockout protection circuit
(3) Output Supply Monitor Comparator (Vcc Comp.)
The short detection comparator in each channel detects the output voltage level, and when any channel output
voltage falls below the short detection voltage, or the SCP terminal (pin 13) voltage falls below the reference
voltage, the timer circuit starts operating and the capacitor C
charging.
When the capacitor charge reaches approximately 0.7 V, the output transistor is turned off and the idle interval
becomes 100 .
When actuated, this protection circuit can be reset by turning on the power supply again. (See “METHOD OF
SETTING TIME CONSTANT FOR TIMER-LATCH SHORT PROTECTION CIRCUIT”.)
A transient state at power-on or a momentary drop of the power supply voltage causes the control IC to mal-
function, resulting in system breakdown or system deterioration. By detecting the internal reference voltage with
respect to the power supply voltage, this protection circuit resets the latch circuit to turn off the output transistor
and set the duty (OFF)
is cleared when the power supply voltage becomes greater than or equal to the threshold voltage level of this
protection circuit.
The output supply monitor comparator compares the output circuit power supply (VCC (O) 1, 3, VCC (O) 2, VCC
(O) 4, 5, 6) to the VCC level, and operates the timer-latch short protection circuit if any of the output circuit power
supplies fall below Vcc
0.65 V.
100 , while at the same time holding the CSCP terminal (pin 23) at the “L”. The reset
SCP
connected to the CSCP terminal (pin 23) starts
MB3825A
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