Hi all,

I am using dual supply opamps in the front end of my prototype USB scope, s=
o=20
I need to generate -5V from the USB +5V.
In the current prototype I am using 2 TPS60401 charge pumps to invert and=20
double the voltage to -10V then regulating to -5 with a standard -5V=20
regulator (I want to keep it as quiet as possible hence the regulation=20
afterwards - this will be replaced with an LDO in the next version also)
This worked okay for supplying one opamp, but drops voltage when supplying=
=20
all three of them (it was only a "temporary" measure until I found a better=
=20
solution)

I guess I could put the TPS60401s in parallel to lower output resistance bu=
t=20
then I would be looking at 4 of them, which seems a bit messy.
Basically I would like to hear of any decent and cheap ways of doing this=20
from anyone who has tackled it before - cheap is important but if there is=
=20
nothing similar in price to the above (~=A30.50) I will pay the extra.
Any advice would be much much appreciated as I can't seem to find anything=
=20
really suitable.=20


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