[SmektHet]

Hi everyone,

I'm working on a high-voltage circuit and I'd like to get some advice before I order the PCB.

The circuit generates around 400 V at low current. The HV section uses a TLC555-based oscillator, an inductor and a switching transistor to step the voltage up from 5 V to around 400 V. There's also a separate impulse detection section.

The lower part of the schematic is the USB-C/battery charging and 5 V power supply.

I've attached both my current schematic and PCB layout.

The stack-up is as follows:

• Signals
• Ground <- only for LV section
• Signals / Power
• Ground <- only for LV section

I'm mainly looking for some advice on the PCB layout:

1. 1. What's the best way to handle the ground in the HV section? Should I use a copper pour or individual traces?
2. 2. How much clearance should I leave between the 400 V traces and GND copper?
3. 3. Are there any particular components or nodes in the schematic that I should give extra spacing around?
4. 4. Is there anything obviously wrong with having the HV section and the USB/battery circuitry on the same PCB?
5. 5. Would an isolation slot or something similar be recommended anywhere?

I'd also appreciate any feedback on the schematic itself.

Thanks!