Looking for a SPI voltage output DAC with an internal buffer amplifier

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Hi All,

I'm looking for a SPI voltage output DAC with an internal buffer amplifier with library support. this will feed into a LT3080 (Adj voltage reg) allowing me to control a laser module that currently runs at full power from a 5V USB connection. Any suggections?

Thanks

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Hi @scarr999

What's the number of bits you're looking for? How many channels? Voltage-buffered, right?

The MCP4912-E/P is a 10-bit, 2-channel, SPI DAC. It is also internally voltage-buffered. There is also an Arduino library for it here:

1 Like
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Hi,

Ideally 16bit double or single channel

Thamks

4

Maybe PT8211 (2 channels, 16 bit DAC) but I don't know if there is an Arduino library for it.

You want to adjust the power of laser LED, right? Why not use a digital potentiometer connected to the LT3080 adjust pin? Or it is best to set the laser LED to full power and modulate its output power via PWM with a logic level MOSFET such as SI2302. This way you will even have a much better efficiency.

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This sounds like a good idea, but I have no spare PWM pins left, have you any knowledge of how to make other none PWM pins into PWM (library etc)

Thanks

6

I don't know if I can help you and hardly anyone else could help you after you haven't said anything about your project - you haven't said which Arduino you use, you haven't published a scheme and you haven't shared your program. We have no idea what you are trying to do with what and how.
Help us to try to help you.

7

Hi, I have no code at the moment or schematic either, I am at the early stage of this. I intend to use a Nano though. I just want to be able to vary the light intensisty of this module that is normally full power via a USB plug.

I have tested the laser module as suggested, varying the current using a PSU didn't really work, then varying the voltage as discussed, it went to about 2.8v without a change and then started to drop quickly until off at about 1.8v. hope this helps :slight_smile:

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That doesn't make sense. When you change the voltage, the current is also change.

Not particularly. We still have no idea what this module is. Publish a datasheet and a link to the module itself.

You haven't said what you want to do yet.

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Sorry, I meant no change in light output as the voltage dropped to 2.8v then the light output started to change until it hit 1.8v (off) The current draw increased.

I have no details on the module, no datasheet or anything it's a 70mw laser module (green) with a USB lead and FC connector to attached it to fiber optic cable.

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You reduce the voltage from 2.8 volts to 1.8 volts but the current increases? Are you sure? This is strange.
Can you post a link from the page where you bought this module?
Can you disassemble it and take picture from inside this module?

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I will double check the statment about the current tonight. I cannot strip the module as it is glued together, here is the link to the module "Here"

Thanks

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Capsule Modules are externally controlled via PWM, and can be hooked up to LED DMX Decoders for easy external dimming.

This is from your link. This means that the brightness can be controlled via PWM, Arduino (maybe Nano) and N channel logic level MOSFET like SI2302.

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