I need to make a circuit board that has the following inputs and outputs:

Inputs and outputs

Inputs:

• $V_{\text{in1}}$ (0-10VDC) PLC controlled signal
• $V_{\text{in2}}$ (0-10VDC) PLC controlled signal
• $V_{\text{batt}}$ (4.8-5.2VDC) battery power. This fluctuates around 5V based on the charge level.

The input signals will be scaled very slowly. Ramps from 0-10V will happen over 100's of milliseconds to seconds. The inputs will sustain their level for a while. Changes are infrequent (30 seconds to > 10 minutes)

The relation between the input and output scale could probably be within a tolerance of 10% max.

The device outputting the signal and the battery will have their ground terminals connected for a shared reference.

Outputs:

• $V_{\text{out1}}$ (2.5-0VDC*) $\implies$ ($\frac{V_{\text{batt}}}{2}$ - GND)** power output
• $V_{\text{out2}}$ (2.5-5VDC*) $\implies$ ($\frac{V_{\text{batt}}}{2}$ - $V_{\text{batt}}$)** power output

Both power outputs must draw current from the battery, up to 1A sustained. The load is a solenoid with continuous positions based on voltage. 3.3v will be a different position than 3.4v and etc.

* This is with respect to their input voltage signal. See the image below

** The output must scale with the battery voltage as a reference. For the rest of the post I will use the 2.5 and 5V values for simplicity.

High level diagram

This is the higher level design for my circuit. The only difference here is the PWM system highlighted in green.

Circuit Diagram

NOTE: The 2 systems ($V_{\text{in1}}$ to $V_{\text{out1}}$ and $V_{\text{in2}}$ to $V_{\text{out2}}$) only differ by the configuration at the LTC6992-1. The circuit does not show duplicated circuitry for the sake of simplicity.

Questions

• Is this design okay? This is my first time making something like this
• From my simulations, I haven't been able to achieve the upper bounds of both functions. How do I get closer to my bounds? and more accurate in general?
• Any general improvements or redesign suggestions?
• I haven't picked an exact op amp model yet. Suggestions for specifications to look out for would be appreciated. Notes on what to look for with MOSFETs and BJTs for this load switch would also be helpful

Datasheets

• LTC6992 series

posted about 16 hours ago

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2h ago

sandwich1699975‭

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