Go Down

Topic: Help designing an op-amp circuit for a galvo driver (Read 355 times) previous topic - next topic

trilithide

Jan 22, 2019, 02:43 am Last Edit: Jan 22, 2019, 05:34 am by trilithide
I have a DAC output that ranges from 0 to 5v, and it's referenced to a power supply that has -15v, 0v, and +15v outputs.

I need to expand my DAC output from 0v->5v to -5v->5v in a way that is still stable at up to 25khz, and doesn't reduce the resolution by much more than half.

Is an opamp circuit the proper way to go about this, or should I be looking at something else?

Grumpy_Mike

Yes an op amp sounds right.
This application note might help you design what you need:-
http://www.ti.com/lit/an/sloa097/sloa097.pdf

MarkT

What resolution is the DAC?  How accurate and/or precise do you want to be?
[ I will NOT respond to personal messages, I WILL delete them, use the forum please ]

TomGeorge

Hi,
Welcome to the Forum.

I assume this is for a laser mirror galvanometer?

Tom... :)
Everything runs on smoke, let the smoke out, it stops running....

trilithide

Hi,
Welcome to the Forum.

I assume this is for a laser mirror galvanometer?

Tom... :)
Yup, trying to build a 30kpps projector!

What resolution is the DAC?  How accurate and/or precise do you want to be?
The DAC is a 12-bit 4096 resolution unit.
Given that I'm shooting for 30,000 updates per second to these DACs, I'm starting to think i2c might not be the best option- opinions?

Grumpy_Mike

Quote
Given that I'm shooting for 30,000 updates per second to these DACs, I'm starting to think i2c might not be the best option- opinions?
I am fully in agreement with you. Standard I2C only runs at 100k bits per second so the fastest you can communicate is 10k bytes per second.

You can up the I2C speed to 400K and even 1M but all devices will not work at that rate.

Better to go the SPI route.

MarkT

Yup, trying to build a 30kpps projector!

The DAC is a 12-bit 4096 resolution unit.
Given that I'm shooting for 30,000 updates per second to these DACs, I'm starting to think i2c might not be the best option- opinions?
So half the resolution is 1 part in 8000?  ie 0.6mV at the output of the DAC - so an opamp would need
to have input offset of 0.5mV or better for that goal, ie a precision opamp of some kind.

What source impedance is the galvo unit?
[ sorry, that should read input impedance ]
[ I will NOT respond to personal messages, I WILL delete them, use the forum please ]

Go Up