CH340K - Unknown USB Device (Device Descriptor Request failed)

Question

I have a Arduino Nano clone working fine with the CH340 drivers. It has a CH340C on it.

I made a custom PCB. CH340 chips are hard to come by these days, so I opted for the CH340K, From the datasheet, seems like it should work similar to the CH340C and CH340G that are quite common.

My PCB has a footprint for both the CH340K and CH340C/CH340G (Yes, I'm aware I'm missing the load capacitors for the CH340G). CH340C/N/K/E and CH340B have built-in clocks without external crystal oscillator. So no need for a crystal.

After soldering on the CH340K and USB port, I plugged the device in, and I'm getting an error in Windows 10 Device Manager:

Unknown USB Device (Device Descriptor Request failed)

Windows has stopped this device because it has reported problems. (Code 43)

The USB set address request failed.

I've uninstalled and reinstalled the CH340 drivers several times. Tried to force the driver onto the device in device manager, and it didn't let me.

There's no short to ground or vcc.

Any help to get this recognized would be great! thanks!

CH340K Pinout

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PCB

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• jsotola: i think that i remember that the driver has inf and ini files associated with it ... they are text files ... some editing may be required ... google CH340K inf
• Thomas Weller: What is "the CH340 drivers"? When I google this, I get 967000 results.
• Majenko: Schematic? PCB design? Without those we can't help you
• EdHayes3: I checked the board, the traces are fine. Just updated post with the Windows error specifics. Maybe I should contact the manufacturer and see if there's an updated driver? I'm not expecting much support from them as the cheap manufacturer they are.
• EdHayes3: Majenko, was the 100nf capacitor for the win! Thought I didn't need it since I wasn't going to be using the LDO output for anything else on the board. Want to make the official answer?

Answer 1

Needed a 100nf capacitor on the v3 pin, per Majenko's suggestion, and per datasheet.

I thought this was only needed if you were going to use the 3.3v output for other purposes. I was wrong!

Same requirement for the CH340C!

Answer 2

on you Pcb the Footprint is not correct! UD+ is on GND, UD- is on UD+ and GND is on UD- . The CH340K has a differnt Footprint.

• Juraj: did you read the other answer by OP?
• EdHayes3: Pin 0 is the exposed pad.