High Voltage  Op Amps - Page 1
Forum section: electronics / beginners

author: JoeyG
author_rank: Regular Contributor
timestamp: June 29, 2022, 12:40:58 am
content: Why would you use a high voltage Op Amp instead of resistor dividers etc.?Higher input impedance ? Faster rise time? Other

author: David Hess
author_rank: Super Contributor
timestamp: June 29, 2022, 12:47:57 am
content: Some applications require or are made simpler with a high voltage operational amplifier. It is possible to bootstrap a low voltage operational amplifier for higher voltage operation or use level shifters but this can get complicated fast.

author: coppercone2
author_rank: Super Contributor
timestamp: June 29, 2022, 02:20:04 am
content: for stuff like electrometers, maybewhen you come across the need it will be obviouswhen you experiment with modified op-amp circuits, you will likely experience frustration. I recommend just getting HV op-amps if you can. The modification of a LV op amp to HV op amp is like something that you should be expect to be paid for, since in most cases it just a BOM cost reduction based on opportunity for certain parts and volumes of scale etc, unless you need something specific, which can be effected by the modification you made.

author: danieljfarrell
author_rank: Contributor
timestamp: June 29, 2022, 06:12:08 am
content: I was looking into high voltage opamps to make a simulated inductor / gyrator for an audio amplifier. But far to expensive for the ones I need.

author: Kleinstein
author_rank: Super Contributor
timestamp: June 29, 2022, 06:16:39 am
content: A divider is not an alternative to an amplifier, it is more like the opposite direction. It is only a few special cases that a divider directly at the input may allow to get away without a high voltage amplifier (more like a buffer).Operational amplifier are conventient building blocks and sometimes the more normal models for a 30-40V supply are not enough. It is possibly to build an amplifier from separate parts (this may include a more more normal OP-amp, but could also be fully discrete). For higher voltage this is sometimes done, as the choice of high voltage OP-amps is limited and power dissipation can become an issue. So the normal SO8 or similar case may not be such a good option.

author: Terry Bites
author_rank: Super Contributor
timestamp: June 29, 2022, 10:23:01 am
content: There is a cheap way to get an HV opamp. Seehttps://www.digikey.co.uk/en/articles/how-to-solve-analog-high-voltage-delivery-challenges

author: Kleinstein
author_rank: Super Contributor
timestamp: June 29, 2022, 10:49:46 am
content: The depeletion mode mosfets are a neat way for bootstrapping, but this only works easy for a buffer and without much capacitive load.

author: mawyatt
author_rank: Super Contributor
timestamp: June 29, 2022, 12:45:32 pm
content: Quote from: danieljfarrell on June 29, 2022, 06:12:08 amThe TI OPA462 might be worth considering, not too expensive (~$20) and somewhat available. We recently selected and used ~300 of these in an experimental phased array controller (basically a 16 bit 256 channel HV AWG), and they have some "additional" features like Overload indication and Enable.https://www.ti.com/lit/ds/symlink/opa462.pdfBest,

author: Zero999
author_rank: Super Contributor
timestamp: June 29, 2022, 02:52:23 pm
content: When a high output voltage is required.It's also possible to add components around an existing op-amp to increase the output voltage and current.