Negative voltage to PSoC pin

[Anonymous]

 What happens when a negative voltage drives the input pin of PSoC? Is it gonne bias the internal transistors which may lead to malfunctioning or is there a breakdown somewhere?

   

And also is there any method wherein I acn generate a -ve voltage using PSoC?

[Bob_Marlowe]

The absolute maximum ratings state that the input to ANY pin may not be less than -0.5V relative to Vss. That implies when you apply a more negative voltage you'll destroy something. For sure!

   

When there is an AC signal to input to a PSoC you ought to use a level shifter.

       

Bob

[ETRO_SSN583]

A negative voltage to a cmos pin can trigger an internal parasitic SCR which

   

shorts Vdd to Vss and generally will blow out the supply die internal bond wire.

       

You can generate a negative voltage using a PWM or Square wave to a pin followed

   

by a diode multiplier, see http://www.gyraf.dk/schematics/Voltage_multipliers_with_CMOS_gates.pdf

   

and http://www.electronics-tutorials.ws/blog/voltage-multiplier-circuit.html and http://www.edn.com/design/integrated-circuit-design/4368224/Voltage-inverter-employs-PWM

       

Regards, Dana.

[ETRO_SSN583]

If you need to level shift a signal into CM range of an input, here is a simple

   

method using just 2 R's -

       

http://electronicdesign.com/analog/use-excel-calculate-d-level-shifter-resistor-values
 

       

Regards, Dana,

[Anonymous]

 Refer to this blog post - http://www.cypress.com/?rID=50815. This is applicable to any single voltage sourced chip.

       

Regards,

   

Kishore.