Hi everyone,

I am working for a company which builds test bench. We have our own standard products but I have a specific need for a project.
I need to have a 0-40V output voltage whereas our product can only provide 0-20V output.
First I would like to say I don't have any experience in PCB design even though I have some basic knowledge.

To be more accurate I need to have 26 channels of 0-40V with at least 10mA max output (no real requirement in term of accuracy). In my system I have more than 60 channels of 0-20V, 14mA max (common ground for all channels).

I see 4 possibilities:
1) Use a Boost converter, but I guess if I double the voltage I will divide the current by 2 (which is not ok since I need 10mA).
2) Use somehow two 0-20V channels to get one 0-40V channel.
3) Use a OPA with gain 2. But it means I need to add a 0-40V PSU in my system for Vs+/Vs- of the OPA (the bench only has 24V PSU). This could be ok but if I have another easier solution that would be great.
4) To buy a board which can already do what I need but I didn't find anything yet (I am also limited by the space, I would say: 25cm*20cm*10cm).

Anyone with good experience could advice me about which direction to take?
Or maybe anyone knows such a 0-40V boost board already existing on the market?

Thank you in advance!
Ludovic

 

Change your PSU from 20V to 40V.

How do you drive 60 channels from one 20V supply?

 

I'm working right now on a circuit that employs a voltage doubler. I think it would be capable of 10mA but not with great efficiency. It probably would need at least 40mA input, I really don't know. A DC-DC converter would do better. I'll post it here if you're interested.

 

What do you exactly mean with "channels"? Are they floating, like in a lab PSU? If that's so, then you should be able to connect two channels in series, right?

 

Thank you all for your comments!

@MrChips
We are using 24V PSU (350W) which is outside of the PCB, and two votage regulators on the PCB (24V=>5V and 24V=> +/-24V) to power the OPAs and other components.
I can't change this 24V PSU since all our system is designed with this 24V PSU, but if it's really needed I could add another 40V PSU to my system to power this "0-40V Boost Voltage Board" and then use OPA with a gain of 2. Each OPA would take one of my 0-20V channel as input and output 0-40V. Do you think it's the best solution? Since I have a common ground on my 0-20V PCB, it means all these gain 2 OPA will have a common minus, I don't know if it can bring issues.

@wayneh
Ok so it seems it's not that easy to use a voltage doubler. I am far to be able to have 40mA as input :/

@Norfindel
These 60 channels have the same ground so it's not floating same as in PSU lab. So I cannot directly connect two channel in series to get 40V. Except if there are some tricks which I am not aware of.

I am not sure I have been clear but my PCB have 60 channels which are controlled by our SW with a range of 0-20V and I need to have a range of 0-40V for a specific project.

 

Only safe way i can think of, is an external 40v PSU with opamps with gain 2. If the opamps can't go to the + rail, the PSU will need to be of a slightly higher voltage (whatever the opamp needs). And make sure that the opamp can supply the output current needed and can work with such a large supply voltage. Remember to use decoupling capacitors on every IC.