IC 7660 showing -2.5 v ?

Sharagim · Jan 3, 2013

Hello,
With a typical circuit as datasheet with a IC 7660 I am getting -2.5v between pin 5 and GND is this correct (Vin is +5v)?

BR,

FvM · Jan 3, 2013

In a (correctly built) typical circuit, 2.5V output would be achieved with about 40 mA load current.

Sharagim · Jan 3, 2013

but isnt it a 5v >>> -5v ? why -2.5?

KonstanU · Jan 3, 2013

No. It is very bad result. It means that you have overload. What is your load and what storage capacitors do you use (nominal capacitance)?

Sharagim · Jan 3, 2013

load is a voltmeter only and I use a 10u capacitor between pin 2 and 4

KonstanU · Jan 3, 2013

But, what about capacitance between output and ground?

Sharagim · Jan 3, 2013

Sorry I forget it , when I put it there (10u) now I see -5
10u is ok ? or I should use more?

KonstanU · Jan 3, 2013

10u is OK. In your case there is no reasons to try change recommended value because you have very low load (high input impedance of voltmeter).

snail888 · Jan 4, 2013

Hi,the exact result should be -5V.And could you post your circuit?

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