To be able to connect some peripheral to digital input, I'm designing the circuit protection to avoid any possible failure due to over/under-voltage issue. So, I will add a clamp protection circuit.
The requirements I need to accomplish are:
- Power Source (Vcc): 3V3
- Max Voltage: 3V9 (3V3 + 0V6)
- Min Voltage: -0V3 (GND – 0V3)
- Max Logic input current: +/- 300nA
The circuit is next:
R1000 is added to limit the current to 10mA.
R1001 is added to limit the input current below 300nA.
My doubts are:
- Might the circuit be modified in case it need to support up to 30V input?
- Which would be the best option for both diodes (Forward voltage, breakdown voltage, forward current, etc)?
- As digital inputs may need to produce a rising interrupt, will be better to add a schottky instead of a zener on D1000?