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TPS92360: Dimming Control Frequency

Part Number: TPS92360
Other Parts Discussed in Thread: TPS92380, TPS61169,

Hi,

When I see the datasheet of TPS92360 or TPS61169, I found >5kHz is recommended at PWM dimming signal frequency. Seeing TPS92380, which is similar part number with TPS92360, however, 100Hz is min Fpwm.

Why does TPS92360 require such a high frequency?

There is a description at 7.3.5 of the datasheet of TPS92360. If just for optimum performance, are the customer able to use below 5kHz? Any concern if they use with100Hz PWM dimming? 

For optimum performance, use the PWM dimming frequency in the range of 5 kHz to 100 kHz. If the PWM frequency is lower than 5 kHz, it is out of the low pass filter's filter range, the FB regulation voltage ripple becomes large, causing large output ripple and may generate audible noise.

Best regards,

Hideki

  • Hello Hideki,

      Our experts for this device are currently celebrating Chinese New Year.  Someone will respond to you next week.

    Regards,

    ~Leonard 

  • Hello Hideki,

    TPS92380 uses digital PWM detector to identify the external PWM signal, so the PWM frequency is a little low because the oscillator is 20MHz. However, TPS92360 utilizes low pass filter to identify the input PWM signal.

    Just as the description of datasheet, if PWM frequency is lower than recommended value, the reference voltage of TPS92360 may have large ripple resulting in output current ripple and audible noise.

    Robin