VoltLog Addresses a CH341 USB Programmer Design Flaw with a Quick and Easy Hack
Putting out 5V where 3.3V is expected is a problem, but one which can thankfully be fixed with relative ease.
Electronics enthusiast Florin "VoltLog" C. has published a video detailing a flaw in the popular CH341A EEPROM and flash memory programmer — and how to fix it so it doesn't damage your components.
"If you watched the previous mailbag video I showed getting this CH341 programmer tool for EEPROMS and flash chips and my viewers were quick to point out this actually has a design problem regarding the voltage levels it puts out," VoltLog explains of the core issue. "It appears there is a 3.3V regulator on board for providing power to the EEPROM or flash chip via the ZIF socket but the CH341 itself is running at 5V - which means it outputs 5V signals on the SPI bus.
"Connecting a 3.3V rated part for programming might result in damaging that part. You might get lucky, you might have a chip that will tolerate that but in general that’s bad practice and so we’re going to attempt to fix it by simply cutting the 5V line going into the CH341 pin 28 and supplying it with 3.3V from the onboard regulator instead."
Armed with a schematic provided through reverse engineering, confirmed with a multimeter that VCC is indeed connected erroneously to 5V, VoltLog sets about fixing the design flaw — a surprisingly simple process which, once complete, helps to guarantee the safety of chips inserted into the programmer.
The full video is available on VoltLog's YouTube channel, with more information available on the blog.
