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Original question:

ULC1001-DRV290XEVM: How to control ULC1001

ULC1001-DRV290XEVM: ULC1001-DRV290XEVM, eval question.

Jin-Suk Choi
Intellectual 2280 points
Part Number: ULC1001-DRV290XEVM
Other Parts Discussed in Thread: DRV2901, ULC1001

Hi~

Customer is under evaluating ULC1001-DRV290XEVM board and got several question as below.,

1. At DRV2901,how to boost output voltage? When see bootstrap, looks charge pump architecture and let me know details. Also can we estimate output amplitude voltage? Is it related to amplitude 0.8puV?

2. Output after LC filter could see sinusoidal wave when input is square wave, can we get filter equation? C, V, Freq? etc...

3. In DRV2901 datasheet, FPWM range is 192~432kHz but EVM has 40-400kHz, which one is right? Also in EVM, no output under 50kHz even though EVM input range, why doesn't work?

4. At EVM GUI,what Freq means at region parameters setting area? Is it resonance freq?

Thanks.

  • 0
    TI__Genius 17630 points

    Hello,

    Thanks for reaching out.

    1. The output voltage of DRV2901 is based on the PVDD voltage as well as the amplitude as it alters the signal coming from ULC1001. The amplitude is essentially controlling the duty cycle. DRV2901 works like a full bridge output stage that switches between ground and PVDD. 

    There is no charge pump architecture, the device uses bootstrap circuitry.

    2. The output LC filter provides a voltage boost. Unfortunately there is not a simple equation to calculate this. Simulation + trial and error is typically needed to optimize this and it is heavily dependent on the lens cover system (LCS) being used. As for the square vs sine wave, the LC filter is also filtering the signal. 

    3. The ULC system has an upper frequency limit of around 400kHz due to the driver and a lower frequency limit of around 40kHz due to ULC1001. The driver has a much lower frequency limit (we need to update this spec in the datasheet), but again the system lower limit is due to ULC1001. 

    4. The region 1 and 2 parameters are based on calibration bursts 2 and 3, respectively. The calibration bursts have a frequency start and frequency stop value which is set around our LCS resonance peaks. The calibration bursts will the measure and calculate the min impendence, peak power, peak apparent power, and min impedance values along with their corresponding frequencies. The calculations are within the frequency range of the respective calibration bursts. 

    Regards,
    Sydney Northcutt 

  • 0 in reply to Sydney Northcutt
    TI__Intellectual 2280 points

    Thanks for your feedback and few more questions.

    1) If OUT A/B frequency is match with LC filter resonance frequency, output makes more higher gain than 1 so make output amplify? am I understood correctly?

    2) amp(puV) change -> PWM duty change -> sinusoidal amplitude change  checked, but duty vs sinusoidal amplitude relationship is reverse, and can I get more detail explanation why? and can we see more detail diagram?

  • 0 in reply to Jin-Suk Choi
    TI__Genius 17630 points

    Hello,

    1. Yes, I think you have the right understanding. Essentially, the LC filter brings the magnitude of the impedance lower, which combined with the equivalent Q of the LC filter will lead to voltage gain (and reactive power) – this is commonly referred to as a ringing system. 

    2. 

    Jin-Suk Choi said:
    amp(puV) change -> PWM duty change -> sinusoidal amplitude change

    Correct. The duty cycle vs sinusoidal amplitude is not inverse though. As you increase the duty cycle the output pwm signals of ULC1001 are higher for a longer period of time and so the amplitude is increased. I might be miss understanding your question though. If so, it would be helpful if you could provide some oscilloscope images of what you are seeing.

    Regards,
    Sydney Northcutt