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Control to DC DC not working

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rrk

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So for my application I am using the PT4523 DC DC (12V 20W 48V-Input Isolated DC/DC Converter) and to switch the DC DC on and off , I have used the optocoupler tclt1103. The input signal to the optocoupler is 3.3V and the limiting resistor is 1.5K from a MCU.
It works fine for a while and then the DC DC stops responding. When the optocoupler is taken off, the DC DC starts to work.

What parameters should I be looking into in the datasheet?
 

bert_kak

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So for my application I am using the PT4523 DC DC (12V 20W 48V-Input Isolated DC/DC Converter) and to switch the DC DC on and off , I have used the optocoupler tclt1103. The input signal to the optocoupler is 3.3V and the limiting resistor is 1.5K from a MCU.
It works fine for a while and then the DC DC stops responding. When the optocoupler is taken off, the DC DC starts to work.

What parameters should I be looking into in the datasheet?
Can you post your circuit?
 

Orson Cart

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Do you need a pull up resistor on the opto collector? or is there a pull up interrnal to the IC? Very occaisionally there is a current drift or build up of charge across the opto and this can be enough to turn it on and keep it on, one solution to this type of problem is to use an opto with an internal shield that is grounded on the secondary side.
You may be able to solve it by putting a 1Meg resistor from the base of the opto to emitter also.

Regards, Orson Cart.
 
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