Pulsed collector current 4n33 optoisolator?

[William At MyBlueRoom]

The continuous collector current of a 4n33 is 150ma, If I vary the duty cycle to 50% can I double the current to 300ma?

The application I have in mind is posted below.

 

[philba]

150 is the absolute max. I try to avoid designing to the maximum. also with Vsat at 1V, 300 mA at 50% duty cycle, you will see 150mW dissipation. This is the spec'd max also. I'd avoid it.

why use an opto? you aren't getting isolation. why not just use a couple of transistors?

 

[William At MyBlueRoom]

Using optos gets me a nice isolation with the HV and I can mux the digit select with only 3 pins. I wonder if there are higher current optos out there?

 

[philba]

unless there are more optos that aren't shown, you are only getting isolation on the 2 CA pins and none of the others. To me, isolation isn't a percentage thing - either you have it or you don.t. also, the power supply needs to be isolated.

when I design isolated circuits, I create a "dmz" that has no electrical connections across it. including the power supply.

 

[ljcox]

You need driver transistors.

The optos could drive two PNP transistors which would drive the display.