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Need increased current for switching a solid state relay

Jay Sircar
Prodigy 10 points


Hi

I have a DAQ with output capabilities of 1 mA max, +-10V. I want to use it to control a solid state relay that switches above 3 V. Using a variable voltage supply, I know that the SSR draws >7 mA @5VDC and has a max of 14 mA).

In other words, I want 5-10VDC 1mA 

to become

>3 VDC >7 mA.

I was going to ask if I could use a MCP1703, to do just that. But a simple energy balance says I can't do it with only two inputs (Vin & GND, limiting my power input to10 mW).

Any assistance will be greatly appreciated.

~j

  • 0
    TI__Guru**** 167696 points

    Jay,

    Using an analog signal to drive a digital relay seems odd , unless you have no more digital outputs and have this unused DAC available.

    This is the most simple solution that came to mind. This works if the SSR is normally off as this circuit only sources current to SSR. If DAC could be active with collector supply voltage off, then adding a base resistor is advised and probably a good idea regardless.