2.8 V Bandgap Voltage to 1.8 V

[ccw27]

If I have a Bandgap Voltage under 2.8V supply at 1.2 V and I want to use this for my 1.8 V supply bandgap reference current, can I simply buffer the bandgap voltage and supply this voltage to my 1.8 V current reference?

Thanks

 

[pokemon]

I think that you can use only one buffer

 

[lastdance]

yes, u can do that, since your BG is ground referenced.

But u have to be aware of situations where the output from your 2.5V system(the buffered bandgap)exceeding the common mode of ur 1.8V bandgap referred current buffer. therefore, u have to check, in transient, what happened when supply glitches high(simulate both high and slow slew rate), during power up, again, high and low slew rate, across Process and temperature. Normally not a problem, but good to do as a sanity check.

You also have to watch for one supply coming up before another supply. u should handle this kind of situation by having some kind of undervoltage lockout circuitry.

 

[ccw27]

For sanity I have used a 3.3V device for the input of the buffer. Also I will carry out the simulations you suggested.

Thanks