MPQ4423 as 1-10V

Automotive Solutions
1

Hi, I am interest about using IC MPQ4423 like driver for ballast 1-10V. Can I use potentiometer one of resistor of divider to change output from 1 to 10V? Driving line about 40meter, quantity of ballast around 20 pcs. And maybe use terminator 300-500R for improove stability?

2

Hello,
With a wide output range of 1V to 10V, there would be some issues on the inductor because it has Vout as one of its determining factors for its value. You could use the largest inductance but would see inefficiencies at different outputs with varying output Vout ripple amplitudes. It is possible to use a potentiometer, but please be aware that the performance may not be optimal at all outputs.

3

If I understand your question correctly you want to use the MPQ4423 to create a voltage to control multiple connected ballasts (light fixtures). If this is correct than I think you have the wrong approach.

You need to have a circuit which can sink current, not source current to create the desired voltage.

1-10V lines in light fixtures induce a small current (typical 0,1mA) on the 1-10V line. This has 2 advantages;

  1. A current source has an infinite input impedance. (high in practice). This makes it possible to connect many light fixtures parallel without resulting in having a low impedance line and heavy control currents (and thus voltage drop in the control line).
  2. When not connecting the 1-10V control line to anything this means the light fixtures see an infinite high resistance, thus creating 10Vdc by themselves. This results in the light fixtures being at 100% (on). Shorting the 1-10V wires is also allowed as the current will be very small. This means the ballasts see a very low resistance thus creating ~0Vdc and switching off the light fixtures

When connecting 100 light fixtures in parallel you will have a control line current of 100x0,1mA = 10mA. This current will travel from the light fixtures towards your control gear. Your control gear then needs to sink this 10mA current to 1-10V depends on setting. This can be done with an opamp or transistor/fet circuit.

Cable length can be 1000 meter without problems and there is no need of termination.

If you just want to use MPQ4423 as a led driver yet control it with 1-10V then you need to add some circuitry which creates 0,1mA on the control line and converts the read voltage to the dim input voltage of MPS ic. This IC doesn’t seem to have a dim input but MPS has very nice chips which have this analog input.