MB3759 Datasheet, PDF (14/27 Pages) Fujitsu Component Limited. – Switching Regulator Controller (Switchable between push-pull and single-end functions)

MB3759
s APPLICATION IN PRACTICAL CIRCUITS
1. Error Amplifier Gain Adjustment
Take care that the bias current does not become large when connecting an external circuit to the FB pin (pin 3)
for adjusting the amplifier gain. As the FB pin is biased to the low level by a sink current, the duty cycle of the
output signal will be affected if the current from the external circuit is greater than the amplifier can sink.
The figure below shows a suitable circuit for adjusting the gain.
It is very important that you avoid having a capacitive load connected to the output stage as this will affect the
response time.
OUT
R1
+
VREF
Vo
−
RIN
R2
RF
2. Synchronized Oscillator Operation
The oscillator can be halted by connecting the CT pin to the GND pin. If supplying the signal externally, halt the
internal oscillator and input to the CT pin.
Using this method, multiple ICs can be used together in synchronized operation. For synchronized operation,
set one IC as the master and connect the other ICs as shown in the diagram.
Master
RT
CT
Slave
VREF RT CT
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