Electronics > Beginners

0-10V controlled via I2C

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permal:
Hi,

My kitchen LED lights are currently driven by one of these DC Maxi Jolly, (English text starts at page 5). The current controller is in turn controlled via RF signal and very unreliable. To remedy that I want to build a new controller.


* Output: 0-10V, 35mA
* Interface: I2C - I'm going to use an ESP32 as the MCU.
* Powered by a single 12V supply (the AUX power from the Dolly driver)
What I need guidance on is with the 0-10V output circuitry:
- Would a DAC101C085 (0-5V DAC, I2C) with a single-supply OpAmp (LM2904?) (non-inverting with a gain of 2; negative voltages not needed) attached to the output do the trick?
- How do I design the output to deliver, say 100mA to have some margin on the required 35mA?

Thanks in advance!

frozenfrogz:
How about using a DAC like this one and an op-amp with x2 gain setting?

permal:

--- Quote from: frozenfrogz on July 20, 2018, 11:35:41 pm ---How about using a DAC like this one and an op-amp with x2 gain setting?

--- End quote ---
You're suggesting the same kind of setup as I did; so my thinking wasn't all wrong then. The MCP4725 and DAC101C085 seems pretty equal except that the former one is half the price.

So what about the sourcing ability of this circuit? For example, LM2904 can only source 30mA (Vcc at 15V), how do I increase that to the required >35mA? Are there any Single-supply OpAmps that are capable of sourcing ~100mA or more?

HB9EVI:
Controlling led brightness over the voltage is nonsense; what you need is a voltage controlled current source; so use a fet with a current sense resistor to build a variable current source

permal:

--- Quote from: HB9EVI on July 21, 2018, 07:54:20 am ---Controlling led brightness over the voltage is nonsense; what you need is a voltage controlled current source; so use a fet with a current sense resistor to build a variable current source

--- End quote ---
I already have the LED driver (linked above). It uses a 0-10V control input signal to determine what current it should drive the LEDs with. I don't see how a variable current source would help in controlling it?

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