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DRV103: Driving a proportional valve

Michele Valdes
Prodigy 10 points
Part Number: DRV103

Hi,

For a new project I will use some proportional valve (SMC PVQ31 - 12V).

All the logic will be handled by a microcontroller and as a proportional valve driver I’ll use the DRV103.

I need to drive the proportional valve in a two step way. 

When a certain output on the uP is high the valve should be driven at about 20% duty cycle. After a certain period of time (about 0,5 sec.) it will be driven at 90% to 100% duty cycle.

I’m planning to use a digital pot to set the duty cycle control pin (1) on the DRV103 and a Voltage reference  IC as a voltage source for this input.

The digital pot value and timing will be handled by the uP.

This is my first time with a driver like DRV103 and I have some question.

1.- Is the digital pot a correct solution to handle different duty cycle ? 

2.- Is there any latency when increasing the duty cycle changing the voltage applied to the duty cycle adj. pin?

3.- how many mA duty cycle adj. input sink ? Is it enough for the voltage reference IC (LM4050AIM3-5.0) to work properly ?

4.- The proportional valve PVQ31 have a working voltage of 12V. Is it ok to supply 12V to the DRV 103 or is better to increase the supply voltage to say 14/15 volt ?

8420.Schematic.pdf

  • 0
    TI__Genius 10855 points

    Hi Michael,

    Welcome to E2E! Thanks for your questions!

    Please keep in mind that these are older devices and we might not have all the technical data you require.

    1: A digital pot can be used to adjust the duty cycle. Here's an example of a Solenoid valve driver using the DRV101. A 1M pot is used to adjust the duty cycle. This design could also provide you with a few tips while making your design; the DRV101 is very similar to the 103. 

    2: Yes, there will be a little latency while changing the duty cycle from 20% up to 90/100% cycle. Unfortunately, we do not have any timing analysis to provide an accurate measurement of this latency. However, I have seen many designs using potentiometers to adjust the duty cycle on the fly.  

    3: Page 10 of the datasheet contains more information on the calculation for the Duty Cycle Adjust input. The current source will provide 2.75 * Iref to the pin. 

    4: The on-resistance of the DRV103 is not significant enough to substantially lower the voltage by itself. Input/output capacitance and resistance could affect the circuit and cause a larger voltage drop, but you'll have to calculate any possible drops across the design. 

    Let me know if you have any more questions!

    Thanks,

    Arthur Huang