# isolated opamps?

Status
Not open for further replies.

#### tmcolby

##### New Member
i am looking for an opamp with an isolated output. does such a chip exist?

i have designed a controller for a continuous wave industrial laser welder. all of my i/o is optically isolated from the laser's i/o. i have one weak link however... the laser output is driven 0-100% by an analog 0-10vdc signal. how can i generate a 0-10v signal with my micro that is isolated from my electronics? any help is appreciated... thanks.

#### dknguyen

##### Well-Known Member
Nope. Two ways to do this:

-Use an variable isolated power supply (a very small one since you just need a voltage signal and not a current) that is being directly controlled by the MCU. Potentially simpler and more straightforward, but slower transient response than the next method.

-Power some regular DAC circuitry off of an isolated power supply. Feed control signals from the MCU to this DAC using digital isolators. Even something as simple as a PWM Lowpass RC Filter DAC will work.

It's easier to pass isolated digital signals than analog ones, so it's better to pass digital signals across the isolation barrier and then generate the analog signal on the isolated side, rather than to generate the analog signal and then pass it through the isolation barrier.

Last edited:

#### Boncuk

##### New Member
Are you sure?

Please have a look at that.

For more examples google "isolated operational amplifier"

Boncuk

#### Attachments

• 585.6 KB Views: 320

#### Papabravo

##### Well-Known Member
As with everything Burr Brown: you can find better components, but you won't pay more for them. Ahhh....cha..cha..cha

#### crutschow

##### Well-Known Member
Burr Brown is now part of TI. Are you saying TI builds poor components?

#### Hero999

##### Banned
You could use an optocoupler with two photodiode or photo transistor outputs so you can use negative feedback to linearise it.

Here are some examples:
IL300
SLC800
http://www.clare.com/home/pdfs.nsf/www/AN-107.pdf/\$file/AN-107.pdf

#### Papabravo

##### Well-Known Member
Burr Brown is now part of TI. Are you saying TI builds poor components?
No! I'm saying you will pay top dollar for all of them.

#### Boncuk

##### New Member
No! I'm saying you will pay top dollar for all of them.
Does the same apply to Analog devices too? They also have isolated amplifiers.

Status
Not open for further replies.