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DRV2510-Q1: input PWM

Arie Li
Expert 3390 points
Part Number: DRV2510-Q1

Hi experts,

I'm a little confused about the operation principle of DRV2510-Q1. Could you pleas help on below quesitons?

1. About BD modulation. From my understanding, the BD modulation is working as below picture shows, the input sinewave and its reserve waveform are compared with a triangular wave and then get the PWM control signal to the internal H-bridge MOSFET. But the input of DRV2510-Q1 is PWM, so could you please let me know how DRV2510-Q1 implement the BD modulation?

2. Could you please give some explanation about the relationship between input PWM and output PWM?

1) If input is in single-end mode

My understanding is the output PWM duty ratio is the same as the input PWM signal, but the output PWM frequency is determined by freq_sel, is it right?

2) If input is in differential mode

What's the IN+ and IN- signal requirement? For example, if I want below output PWM, what signal should be added at IN+ and IN- respectively?

3. Shoud customer add LC filter at OUT+ and OUT- like class D audio amplifier? It seems the LC filter is optional.

Arie

  • 0
    TI__Genius 13610 points

    Hey Arie,

    PWM would still go through process comparing with triangle wave with selected frequency except since it is PWM already it will result in an output exactly same except at the peaks and bottoms of the triangle waves there will be dips or peaks that will look like noise. If an LC circuit was implemented than you filter out that switching frequency noise and get a PWM output exactly same as PWM input. Actuators are not affected by such high frequency switching so LC circuit is optional.

    This is assuming PWM is same voltage as Vdd if you do less or and change your gain the PWM then would have wider gaps at the switching frequency making it more and more of a 500kHz PWM but the periods would be tiny compared to whatever your input PWM looks like and like I said before can be filtered- out with LC filter and wont affect actuator performance regarless of there being a filter.

    So there is no relationship in terms of frequency of input PWM and output PWM, just line a sinewave's frequency doesnt affect it.

    Does that answer your question?

    Best,

    Carson

    Low Power Audio Apps

  • 0 in reply to Carson Allen
    TI__Expert 3390 points

    Hi Carson,

    Thanks for your reply, so what's the PWM requirement at IN+ and IN- pin? They should be complementary signals? I mean IN- is the inverse signal of IN+?

    Arie

  • 0 in reply to Arie Li
    TI__Genius 13610 points

    Hi Arie,

    Yes it could be complementary or single ended, this chip is not explicitly made PWM input so you should treat a PWM input signal the same way you would treat a signal like a sinewave.

    I think you might be getting confused with the example circuits they show in the datasheet having a microprocessor output PWM, that PWM goes through a LPF before going into DRV chip. So it gets filtered into sinewave before reaching the device.

    Is that clear?

    Best,

    Carson