My circuit includes the following components:

• PIC16 with internal clock, frequency: 32 MHz
• ST LED2000 LED driver (a buck converter) with a PWM dimming input
• TI BQ24070RHL battery charger
• LED controlled via PWM by the microcontroller.

My question:
Do the following signals qualify as high-speed?
I’m asking this to determine whether I need to ensure a proper return path for them and/or maintain large spacing between them.
If not, can I ignore the return path considerations?

Key signals I believe require attention:

1. Charger outputs – These are open-drain outputs. These outputs are connected to the microcontroller inputs (with internal PU). I couldn't find rise/fall time specifications in the datasheet.
2. PWM outputs from the microcontroller– Base frequency: 200–500 Hz.
   • One output goes to the LED driver (possibly with or without a pull-down resistor).
   • Another output drives an LED.
3. Push button with a pull-down resistor, connected to a microcontroller input.

Thanks in advanced for any answer,
Eyal

 

Nothing special is required for those signals.

 

Those signals need no special consideration, but they do obviously need a return path, as do all signals.

 

I mean - do they need a close ground as a return path, as they have fast edges

 

I mean - do they need a close ground as a return path, as they have fast edges

Certainly that's a consideration, as fast edges can cause ringing on the signal edge if there is a poor ground return path.
It's always good practice to have a short ground return path for all signals.
Decoupling each IC directly from power to ground with a 100nF ceramic capacitor is standard practice to minimize such problems.

 

Thanks!