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TPS543320: What happens if you use RMODE value NOT in datasheet table

Part Number: TPS543320

I am using a TPS43320 to regulate 12V to 3.3V, and was wondering what the effect of an invalid RMODE resistor is? I just noticed we are using 11.8kΩ for our RMODE, but that isn't a value in the table. Rather, 11.3kΩ is instead.

Would this cause irregular behavior or anything of the sort?

  • Hi Dylan,

    We still recommend to use accurate 11.3k resistor with 1% or less tolerance for mode pin detection even if 11.8k works. 

    Generally 11.8k would be detected as 11.3k since the next gear is 14.3k. 

    The mode detection is realized by forcing a fixed current on the resistor during powering up and detect the voltage using a DAC to figure out which mode is chosen.

  • Hey Athos

    Could there be any adverse effects from using the wrong resistor value?

  • Hi Dylan,

    The wrong resistor value would influence the mode selection including current limitation, ramp compensation and soft-start time.

    For example, if you use a 13k for 11.3k and be detected as 14.3k gear, the soft-start time would be changed from 1ms to 2ms.

    If using a wrong resistor, the device would at least choose a adjacent mode. There couldn't be any serious effect that the device damage or couldn't start up.