Electronics > Repair
CH341A Serial Memory Programmer Power Supply Fix
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PostNubila:
This is my mod of the CH341A. I change it to 3.3V and added 2 ZIFs: 1 for 3.3V and other for 5V (used a YF08E to convert 3.3V to 5V).
The ZIFs are 24 pin so now I can program 24xxx, 25xxx, 95xxx and 93xxx eeproms!
firepower:
Found these two models searching for CH341A Programmer online. Has 3V3 connected to VCC of CH341A as well as socket & ICSP. has area onboard to clamp SOP8 / SOP16 chip using clothes peg :D
No modding needed.
I bought the blue version.
Mcast:
Hello, I have a question. I lifted pin 24 and soldered on pin 2 of the 3.3 volt regulator and it worked perfectly. Why do I need to wire pin 9? What does pin 9 do? Thanks.
johnmx:

--- Quote from: Mcast on January 18, 2021, 07:51:12 pm ---Hello, I have a question. I lifted pin 24 and soldered on pin 2 of the 3.3 volt regulator and it worked perfectly. Why do I need to wire pin 9? What does pin 9 do? Thanks.

--- End quote ---
This chip has an internal +3.3V regulator. It is used when the device is powered by +5V. When the external power supply is +3.3V, it is necessary to bypass/disable this regulator by connecting +3.3V to pin 9.
Mcast:
Thanks for the information.
You're right, I used the datasheet of USB serial converter CH340 as a reference:

"CH340 supports 5V and 3.3V operation. When using 5V operation, supply 5V to VCC pin, and
decouple the internal 3.3V reference with a capacitor of 4.7-20nF from V3 pin to ground.
When using 3.3V operation, tie V3 pin to VCC pin and supply 3.3V power."
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