PSoC 5 KIT -5v output?

[Anonymous]

 Hi Is there a way to get -5 or -3.3V out of PSoC5LP Kit powered by USB?

[Bob_Marlowe]

Since the PSoC input signals must be greater than 0V there was no need to design a negative voltage on the board. Only the UART-interface chip generates a negative voltage to be used for RS232, but that is not stabilized.

   

What do you need negative voltages for?

       

Bob

[Anonymous]

 Thanks Bob, I knew Vssa is the lowest you could get pretty much, I need the differential voltage to power an opamp. Do you think there's a way to stabilize the RS232 port output? 

   

update: more info here thanks to google 

   

http://www.epanorama.net/circuits/rspower.html

[Bob_Marlowe]

Can't you use the PSoC5 opamps with a level-shifter to have their inputs between GND and VCC?

       

Bob

[ETRO_SSN583]

Two approaches -

       

1) Gen the negative supply with didode charge pump or external sw cap

   

chg pump reg.

       

2) Offset signals going into PSOC.

       

Attached some info on doing both.

       

www.dropbox.com/s/k1yn4m7heaixvmg/ADinput%20negative%20inputs.zip

       

Regards, Dana.