Electronics > Repair

CH341A Serial Memory Programmer Power Supply Fix

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md5001996:

--- Quote from: likorna on July 04, 2024, 07:57:49 am ---My modification of the black programmer. It can be switched from 5V to 3.3V and from 3.3V to 5V. For 1.8V chips I use a simple adapter.

--- End quote ---

See my pics... i cant solder as says in your photos...

Tantratron:

--- Quote from: fulda on February 12, 2019, 12:38:16 pm ---
--- Quote from: johnmx on October 14, 2017, 12:29:37 pm ---All Vcc connections in the ZIF socket are 3.3V but the CH341A is powered at 5V.
So all I2C and SPI signals are 5V while the external memory is powered at 3.3V.
There are no limiting series resistors on those signals.

One simple solution to fix this issue is to simply bypass the 1117-3.3V regulator.
I can use the hot air station to remove the 1117 and then short-circuit the input with the output.

My question is, is it safe to just do the short-circuit without removing the 1117 linear regulator?

--- End quote ---

Hi,

The trick is, that you miss 2nd LDO, that is inside CH341A chip.
Check datasheet.

At end of chapter 5.2 硬件说明 (Hardware description) is stated:
CH341芯片支持5V电源电压或者3.3V 电源电压。当使用5V 工作电压时,CH341 芯片的VCC 引脚 输入外部5V 电源,并且V3 引脚应该外接容量为0.01uF~0.1uF 的电源退耦电容。当使用3.3V 工作
电压时,CH341 芯片的V3引脚应该与VCC引脚相连接,同时输入外部的3.3V电源,并且与CH341芯
片相连接的其它电路的工作电压不能超过3.3V。
It can be translated:
The CH341 chip supports a 5V supply voltage or a 3.3V supply voltage. When using a 5V supply voltage, the VCC pin of the CH341 chip inputs an external 5V power supply, and the V3 pin should be externally connected with a power supply decoupling capacitor of 0.01uF to 0.1uF. When working with 3.3V voltage, the V3 pin of the CH341 chip should be connected to the VCC pin, and an external 3.3V power supply is input, and the CH341 core is connected.
The operating voltage of other circuits connected to the chip cannot exceed 3.3V.

As far as I understand, that mean, that chip have internal 3.3V regulator and IO pins are NOT 5V tolerant. It mean, it always use 3V3 for communication with eeprom.

--- End quote ---

Hello, I've purchased this week from Amazon this model https://www.amazon.fr/gp/product/B07SNTL5V6 but I would need some confirmation or help regarding if the 5V issue is solved nowadays.

Attached 2 pictures of the programmer, I've only connected to my USB port from my iMac then used my DDM to check the 8 pins corresponding to target SPI NOR chip (25D40 so 3.3V). I have not yet connected the SPI NOR memory to avoid any frying so the voltage values read from the CH431A connector are not loaded. It seems that Vcc (pin 8) Hold (pin 7) Write Protect (pin 3) do show 3.3V but how about the 4 pins (Chip Select, MISO, MOSI and CLK) which show 5V ?

The jumper supposed to select 3.3V is shown in the pciture but does this model will self-shift to 3.3V on all pins, why some pins are 5V and other 3.3V ?

Thank you in advance, Albert

Ian.M:
A CH341A chip with no additional dual supply level shifters cant "self-shift to 3.3V" when a serial EEPROM or FLASH memory is connected.
What is actually happening is the  memory is dragging down the signal voltages, and possibly dragging its Vcc supply above 3.3V, via the memory's input clamping diodes.  As David said back in reply #81

--- Quote from: DavidAlfa on June 16, 2023, 07:38:51 pm ---You're forcing the pins to clamp the voltage coming from the ch341, it's up to you to "freak out" or take the risk.
But one day you might want to read some important memory and get a surprise.

--- End quote ---

You have the same issue the O.P. did when he started the topic, and you need to do the mod to work safely with 3.3V memory chips - either the permanent 3.3V mod or the switchable version if you also need 5V capability.

flachyjoe:
Hi !

I've buy this one https://www.ebay.fr/itm/324505422583 I've received a black card labelled "CH341 Pro" on front side and "CH341 MinProgramment" on back. No "a" !? and no version number.

The top pin row is marked "1 2 3 TX RX GND 3.3V" when I see "1 2 3 TX RX GND 5V" on the previous posted picture. Could it be a fixed design ?

Tantratron:
Bonjour flachyjoe,

Ther seems to be a slight difference between CH341 and CH341A, look this here which part of is translated in french

En mode port d'imprimante, le CH341 fournit un port d'imprimante USB standard qui combine le protocole USB et le système d'exploitation Windows utilisé pour mettre à niveau une imprimante parallèle ordinaire directement vers le bus USB. En mode parallèle, le CH341 fournit un parallèle 8 bits en mode EPP ou MEM. Il peut être utilisé pour entrer/sortir des données directement sans MCU/DSP. En outre, le CH341A prend également en charge certaines interfaces série synchrones courantes telles que les interfaces 2 fils (SCL, SDA) et 4 fils (CS, SCK/CLK, MISO/SDI/DIN et MOSI/SDO/DOUT).

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