Optoisolator question

[rnielsen]

Greetings!

I need to ask for advice on an appropriate optoisolator to use in my current project. I have used them quite a bit but not for communications so I'm not that knowledgeable on their timing characteristics.

I am trying to interface a PIC to a motor controller that uses +/- 15v on it's inputs. I have a 4N36 opto hooked up but the slew rate is killing me. It responds just fine to the first edge but when the input is removed the output acts like a cap that is slowly discharging. I have the output emitter tied to ground and the collector tied to VDD thru a resistor. I'm then taking the signal from the collector.

I am trying to communicate to a digital potentiometer, that is connected to the controller's input, via a 3-wire serial line. I need to isolate these lines from the higher voltages. Any suggestions on an good opto that will allow the digital signals to go through it at a higher rate?

I've looked around a bit but I'm not sure which ones will work the best for me so I figured that there's plenty of people here that have used them a lot. A dual or quad output configuration would be ideal in order to keep the pc board area down.

Thanks,
Ronald

[valemike]

I once tried designing in a hi speed HCPL-0531 which is a dual opto, but never did use it.

To communicate between a PIC and a motor drive module (15V), my partner/Dad likes to use the H11L1 from Fairchild. It's a schmitt trigger output and hi-speed opto, but it's only a single one. It does cost cheaper though.

[Humberto]

The way is using an optoisolator with logic gate outputs, they are fast enough
(propagation delay time in ns range) and the outputs are sharp logic levels,
most of them open collector type. I used the 6N137 but Fairchild has a wide line,
try the HCPL-26xx family.

Humberto

[Alexander]

Hello,

in a similar project i have used the ADUM1300 - Triple-Channel Digital Isolator from Analog Devices.

http://www.analog.com/en/prod/0%2C2877%2CADUM1300%2C00.html

Best regards