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TPS3702-Q1 with external resistor

Ryuji
Guru 20090 points
Other Parts Discussed in Thread: TPS3702-Q1, TPS3700-Q1

Hello,

I would like to sense the following voltage. However there is no voltage option for these power rail.
Thus, I would like to use TPS3702-Q1 with external resisotor.
Since the customer request the +/-1% accuracy, we couldn't use the TPS3700-Q1.
Can we use TPS3702-Q1 with external resistor?
If yes could you please let me know the calculation method and recommended resistor value? 

(1) Rail : 1.03V, UV : 0.96V +/- 1%, OV: 1.04V+/- 1%
(2) Rail : 1.35V, UV : 1.3V +/- 1%, OV: 1.4V+/- 1%
(3) Rail : 1.25V, UV : 1.18V +/- 1%, OV: 1.31V+/- 1%

Best Regards,
Ryuji Asaka

  • 0
    TI__Mastermind 43580 points

    HI Asaka-san,

    The minimum monitoring voltage is 1.0V and yes you can use resistors to monitor non-released voltage thresholds. However, without resistors, the best window tolerance we have is +/-3%. So without resistors we are looking at 0.97 for UV and 1.03V for OV detection. Of course when you add in the accuracy over temperature this becomes +/-3.9% worst case. If you add external resistors to adjust the threshold then worst case you are adding two 1% resistors so now the total accuracy would be 5.9%

    Also please note that the input sense current is worst-case 1.5uA so you would need to make sure that the resistor divider chosen uses small enough resistors to swamp out this input leakage current.

    I hope this helps.