Decoupling 3.3v to 5v

Eugeneo · Joined: 30 Aug 2005 Posts: 155 Location: Calgary, AB

I'm interfacing a M25P20 (2mbit cheap flash ram chip) and a pic 16LF819. The problem is my ICP is 5 volts so I need to decouple the flash chip from the power circuit, clock and data lines. Since there are all surface mount components, I can't just pull it off during programming. I've thought about dropping my ICP voltage to 3.3 but the programmer chip is not a low voltage device. Just so I can develop this thing, I've got jumpers on the board to completely disconnect it. For future is there any other options available that you guys could recomend?

MikeValencia · Joined: 04 Aug 2004 Posts: 238 Location: Chicago

I once had a simple circuit where two AA batteries got me 3V. All I powered up was an LCD and a PIC. I used a self-powered ICD-2 to flash the PIC 16LFxxx chip.

The ICD-2 can use its own power from an adapter. Can't you directly program the PIC with a self-powered ICD-2?

Guest · Posted: Mon Sep 05, 2005 2:37 pm

That's the problem, my ICD doesn't function at 3 volts. But now that you mention it, finding an ICD that runs at 3v then self powering it, sounds like a great idea. As long as the charge pump puts out enough for MCLR. Or I guess I could go to LVP as well.

Thanks for you help

kender · Joined: 09 Aug 2004 Posts: 768 Location: Silicon Valley

Here's a monologue on the subject, which might be useful:
http://www.ccsinfo.com/forum/viewtopic.php?t=20395

Eugeneo · Joined: 30 Aug 2005 Posts: 155 Location: Calgary, AB

Very helpful, thanks you for that.