2
\$\begingroup\$

While bored recently, I decided to take apart a few old pieces of electronic equipment and attempt to reverse-engineer them. I've been doing pretty well, but I've come to an IC that I can identify but doesn't seem to exist on the manufacturer's website.

Specifically, it's an SOP20 package marked "I87-0205-000 1202S7E", with Microchip's logo on it. I'm fairly new to this, but context clues (looking at the board) suggest that this is some kind of MCU, which makes sense, given the manufacturer. I've tried googling these numbers, and while I get about 8 billion results on Alibaba with vendors willing to sell me hundreds of them, none of them actually tell me what it is, or offer any datasheets. I've tried contacting a few of these vendors asking for datasheets, but none have gotten back to me yet.

So, anecdotes aside, are there any good methods of figuring out the name of a chip/finding the datasheet for a somewhat unidentifiable chip?

\$\endgroup\$
4
\$\begingroup\$

You've pretty much got the process down.

Recognize that some parts, such as mask-programmed microcontrollers and perhaps some pre-programmed flash microcontrollers may be house numbered, which means they have a part number assigned by the customer, not the manufacturer, and no information will be forthcoming from the latter, nor will you likely ever find a datasheet. The part may or may not be basically a standard part.

Sometimes, especially with microcontrollers, you can match the package, manufacturer (if known) and the pin pattern (things like power pins, crystal pins, etc.) to reduce the number of options, but it's not an especially rewarding exercise unless you're being paid to analyze someone else's product. The magic is all in the firmware in such cases, and it will be copyright (as well as hardware locked, though that doesn't slow down some unethical folks much).

\$\endgroup\$
2
\$\begingroup\$

Unfortunately, I believe searching the web the contacting the manufacturer is all you can do. Besides that, using as many clues from the rest of your circuit is your best bet. I searched I87-0205-000, and based on these links:

http://au.alibaba.com/product/1630440539--electronic-component-I87-0205-000.html http://au.alibaba.com/product/733777980-I87-0205-000-IC-Supply-Chain-.html

it looks like it could be a voltage regulator. To see if it is a MCU, so you can look to see if there is a separate power supply circuit on the PCB. Or does this chip appear to be accepting input from a battery or other power source and conditioning it for other ICs? A MCU would also have bypass capacitors nearby. If it's an older device, the MCU would surely have an oscillator nearby as well. If it is a microprocessor, not a microcontroller, there would be external memory on the board too. Good PCB design would have the MCU and high speed signals clustered together, away from the I/O. A voltage regulator would probably have some larger capacitors nearby to filter a dirty input signal.

Based on what the equipment does, it is best to identify the purpose of as many components as you can and see what you are left with.

\$\endgroup\$

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.