Matrix user forums

Does someone has a suggestion to realise an DAC with 7Volt maximum output and 30mA?

With kind regards

Jan Lichtenbelt

Hi Jan,

Sounds like a job for an op amp. You should be able to make a basic amplifier and use resistor values to give you say 1.5 x gain so 0-5V becomes 0-7.5V. Of course the op amp will need access to the higher voltage for it's positive rail.

Vout = Vin * (1 + (R2 / R1))

R1 = 2K
R2 = 1K

7.5V = 5V * 1.5

https://en.wikipedia.org/wiki/Operation ... _amplifier

It's a good idea to use an Op Amp With a DAC anyway as often the DAC output has extremely low driving current and so an op amp even in unity gain mode (1:1 Input Voltage to Output Voltage) will provide a level of buffering and current amplification.

Beware not all op amps are made the same, some can handle rail to rail outputs and some cannot.

The forum https://www.circuitsonline.net/forum/ learned me the OpAmp OPA547. This OpApm needs a voltage between 8 and 60V with a 500 mA output.
It is very interesting for microcontroller user, because the DAC output can directly control the output current of this OpAmp. Just what I need.

Kind regards

Jan Lichtenbelt
PS. OPA in Dutch means grandfather in English. That is in agreement with my age.