ADA4700-1 Single Supply

Hi amagyar377 ,

 Yes, you can use the ADA4700-1 with an unbalanced supply, but you should consider the input and output headroom. Based on the specification table, the input headroom must be around 3V away from the supply and the output should be 1.5 away from the supply.  

Hope this information helps.

Thanks,

Mae

Dear Mae,

Thanks a lot for the quick response!

Unfortunately, our input signal is from 0 to 5V to be amplifier to 45 to 55V.

Do you have another amplifier that is also high voltage and can do rail to rail with unbalanced supply?

Regards,

Andras

Hi Andras,

Upon checking the Selection Table for High Voltage Op Amps ≥12V | Parametric Search | Analog Devices, it seems that we don't have an exact rail to rail amplifiers like you need. In order to have an input of 0-5V and an output of 45-55V, you may need to adjust the supply.

For example, as seen in the parametric table, the ADA4099 is categorized as rail-to-rail input and output, but looking at the datasheet, the ADA4099 output voltage swing is typically 45mV away from the voltage rail if there's no load. 

Hence, there's still a headroom for output in reference to supply.

Is your system flexible with extending the supply rail?

Thanks,

Mae

Hi Andras,

Upon checking the Selection Table for High Voltage Op Amps ≥12V | Parametric Search | Analog Devices, it seems that we don't have an exact rail to rail amplifiers like you need. In order to have an input of 0-5V and an output of 45-55V, you may need to adjust the supply.

For example, as seen in the parametric table, the ADA4099 is categorized as rail-to-rail input and output, but looking at the datasheet, the ADA4099 output voltage swing is typically 45mV away from the voltage rail if there's no load. 

Hence, there's still a headroom for output in reference to supply.

Is your system flexible with extending the supply rail?

Thanks,

Mae

Hi Mae,

ADA4099 is a nice one, thanks but we will have to adjust the supply for sure for this. I think zener in series with the V+ will do since it does not consume a lot at all.

I found another one in the meantime:

https://www.analog.com/en/products/ltc2057.html?tab=documentation-pane-1#product-overview

This is also fine, but I think the one you sent  (ADA4099) is more adequate for my application. What do you think?

Thanks,

Andras

Hi Andras, 

Based on the given requirements, specifically the input and output, I think LTC2057 is a better fit because the input and output headroom is much closer to the supply. The LTC2057 output voltage swing is typically 0.2mV away from the voltage rail if there's no load, while ADA4099 is typically 45mV. 

But are there any other critical requirements in your application like the short circuit requirement? 

Regards,

Mae

Hi Mae,

Right! Plus, LTC2057HV has maximum of +60V supply so that is another important point.

Actually we do not want to load the output of the amplifier more than 1-2mA for sure.

Also we will adjust the gain to account for this headroom so for this amount of current we will not have any problem.

I think we are fine with this! Thank you for your assistance and have a great day

Regards,

Andras