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LM3429: Heater pad control by LED driver?

Chris van der Aar
Intellectual 480 points
Part Number: LM3429
Other Parts Discussed in Thread: TPS92691

For a new project we are starting we need to control a polyamide heater pad with a maximum power of 160W 24V Hz. We have a temp sensor for measuring the temperature and a T.I. Piccolo DSP for control of the complete system.

Of course we can just switch on and off the heater pad depending on the temperature but probably this causes peak currents on the supply line. Therefore maybe a better solution would be a controller to have a more smooth control of the regulated power.

Do you think it is possible to use a LED driver (e.g. a LM3429 or something else for this application ? Or do you suggest another part for this? 

With our Piccolo DSP we are able to generate PWM so we could use a driver with PWM control.

The heating power we need will be around 90W and is used for heating fluid in a tank. The heater pad can generate max 160W but we don't use that max power.

So we need at least a  driver with a controlled output of 4A at +24V (or e.g. 5A at +20V )

Regards


Chris van der Aar

NTS Systems Development

Eindhoven, The Netherlands

  • 0
    TI__Genius 17690 points
    Hi Chris,

    In reality, your DSP is already a controller so it can provide PWM control to a FET to turn on and off the heater pad but your main concern is the pulsating current on the supply line. You can use an LC filter to filter out this pulsating current if the PWM frequency is high enough like 100KHz.

    If the heating pad is far away from the switching FET then the above suggestion can be an issue because of the impedance and you might want to use the TPS92691. With this part you will have direct control of the ouput current via the IADJ pin so you do not need to PWM the output current to control your temperature. The input current will then be DC after the LC filter. If the input voltage is higher than the output voltage then you would use the BUCK configuration. If you use the BUCK then we have a typo on figure 27...The signals from RCS to pin 9 and 10 are swapped.

    Thanks Tuan