Recording multiple ISD chips at once

Thread Starter


Joined Oct 8, 2019
As part of our product line, we use ISD4003-05MPY chips to record music and sound effects into six different areas of memory. As the part number implies, it holds 5 minutes of audio and takes quite some time to record dozens of chips as needed. Does anyone have an idea how to record multiple chips at one time? If you parallel the chips, they will record but the sound gets distorted. I am guessing the internal oscillators are interfering with each other. The parallel method works when programming PIC microcontrollers but not these ISD Chips. Thank you.


Joined Sep 22, 2012
If you're just tying the analog inputs, I could see that as an issue. A unity gain buffer amp to each chip should provide the isolation they need. The address lines, being digital, should be ok to bus, but easily buffered too. I used ISDs in museum exhibits - fun stuff.

Depending on the number to program for production, I'd think on a micro controller to set addresses and start/stop each audio segment using one ISD as the source and some number of buffered units to be programmed. Set the address bus, enable master play / slave record, run a timer for segment length, then repeat for all segments.
It'd be a fun little project. Good Hunting <<<)))