TMS320F28384S: Device reset threshold

Luke Chen

Hi champs,

In F28388D controlCARD, we use TPS3702CX12 and TPS3702CX33 to monitor +1.2V and +3.3V respectively.

The UV threshold of TPS3702CX12 is +1.09V, TPS3702CX33 is +3.0V. However, the minimum recommended operating voltage of VDD is +1.14V, VDDIO is +3.14V. My customer would like to know how we determine the UV threshold of VDD and VDDIO to reset F2838x, is there any selection rule?

Please advise your comments.

Thanks and regards,

Luke

over 4 years ago

0 Frank Ankapong over 4 years ago

TI__Mastermind 28275 points

Hi Luke,

The UV threshold to use is indeed the min recommended operating voltage of the rails. i.e 1.14V for VDD and 3.14V for VDDIO.

0 Luke Chen over 4 years ago in reply to Frank Ankapong

TI__Expert 5090 points

Frank,

Do you mean if possible, the best way is to set UV threshold 1.14V for VDD and 3.14V for VDDIO?

Regards,

Luke

+1 Frank Ankapong over 4 years ago in reply to Luke Chen

TI__Mastermind 28275 points

Luke,

The device min recommended operating condition for VDD is 1.14v and VDDIO 3.14v. The usefulness of a supervisor is to trip before the rails dip below those levels. If the supervisor can't trip below those levels, then it is actually not useful since it is not protecting the device and it's no difference from not having a supervisor. Let us know if this is not clear.

0 Luke Chen over 4 years ago in reply to Frank Ankapong

TI__Expert 5090 points

Frank,

In the controlCARD design, we use TPS devices and set UV threshold of VDD is +1.09V and VDDIO is +3.0V, these two UV thresholds are lower than the min recommended operating condition.

My customer wants to know is it any side effect? should he follow this design or look for other supervisors for VDD and VDDIO? Please advise, thanks for help.

Regards,

Luke

0 Frank Ankapong over 4 years ago in reply to Luke Chen

TI__Mastermind 28275 points

Luke,

Let me check with the controlCARD team about the supervisor choice. Will get back to you.

+1 Cody Watkins over 4 years ago in reply to Frank Ankapong

TI__Mastermind 42195 points

Luke,

These voltage monitors are configurable to two different levels. In our implementation the "SET" pin is > VIH(SET). This means the device uses the tighter tolerance ranges as described in Table4 " release devices thresholds".https://www.ti.com/lit/gpn/TPS3702

For example TPS3702CX12 UV is 1.15 and OV is 1.25 when the set pin is pulled high. These are tighter than the F28388D limits of 1.14 and 1.26. Similarly for the 3.3V monitor its ranges are tigher too, all of these ranges can be found in the datasheet linked above.

Regards,
Cody

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TMS320F28384S: Device reset threshold