TPS3808: Reset width of MR

Dice-K

Mastermind 6827 points

Part Number: TPS3808
Other Parts Discussed in Thread: TLV840, TPS3435, TPS3840, TPS3890

Hi support team,

I have a question about reset width of MR pin of TPS3808.

According to the SBVS050M, it is 0.001μs (typ), which is considerably shorter than SENSE's 20μs (typ).

Isn't it a typo?
Isn't it 0.001ms (1μs) instead of 0.001μs (1ns)?

For example,
TLV840 is 500ns (0.5μs).

TPS3435 is 100ns (0.1μs) .

Regards,
Dice-K

over 1 year ago

0 Sila Atalar over 1 year ago

TI__Expert 5420 points

Hi Dice-k,

There is no typo in the datasheet. I checked earliest revisions and they have all 0.001 us

If you look at the functional block diagram for MR_bar pin is not flooding. MR_bar pin has that internal pull up resistor for glitch protection, that's why it has shorter width than sense pin.

Best Regards,

Sila Atalar

0 Dice-K over 1 year ago in reply to Sila Atalar

Mastermind 6827 points

Hi Sila,
Thank you for your reply.

1ns is extremely short compared to other devices.
Why is it so much shorter than other devices?

It's an old device from 2004 and I think it's hard to get information about it.

Best regards,
Dice-K

+1 Sila Atalar over 1 year ago in reply to Dice-K

TI__Expert 5420 points

Hi Dice-K,

The MR pulse can be as short as 1 ns for flexibility. This was a design choice and we do not have background on a device this old on why the design choice was made. Please feel free to use a much longer pulse depending on your requirements. TI has other supervisors with longer MR pulse.

Best Regards,

Sila Atalar

0 Dice-K over 1 year ago in reply to Sila Atalar

Mastermind 6827 points

Hi Sila,
Thank you for your answer.

I have understood that 1ns is definitely correct.

In the threads below, MAX is written as 20ns, and the other thread is written as less than 10ns.
e2e.ti.com/.../tps3808-mr-pulse-width
e2e.ti.com/.../about-mr-pin-of-tps3808
For safety, I want to secure 20ns or more.

Either way, the TPS3808 MR pin can be sensitive to noise.
e2e.ti.com/.../tps3808-ep-mr-pulse-width

I would also like to consider the TPS3890 (MIN:1000ns), TLV840 (TYP:500ns) and TPS3840 (TYP:300ns), which require longer MR pulses.

Best regards,
Dice-K

0 Sila Atalar over 1 year ago in reply to Dice-K

TI__Expert 5420 points

Hi Dice-K

I'm happy to help. I need to close the thread if there are no further questions.

Best Regards,

Sila Atalar

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TPS3808: Reset width of MR