reference voltage generation of -2V

[sofia_huze]

reference generation

hello all,

i have a voltage which varies as vdd= 5v to 30v, i need to generate a voltage which is vdd-2v.

any circuits ideas or references

please help me

sofia

 

[gevy]

Re: reference generation

You can generate floating reference voltage -2V relatively supply line, i.e. create floating voltage source connected to supply.

 

[erikl]

Re: reference generation

If it doesn't have to be very precise, you could use an LED with appropriate forward voltage of about 2V (a yellow one, perhaps) from VDD in series with a resistor (or better: a constant current source, e.g. a JFET) to GND .

 

[Siniša]

Re: reference generation

Shunt regulator like lmv431 will do the job.