TPS65400: TPS65400 external clock related question

Lee HongGyo

Part Number: TPS65400

I have the following inquiry regarding the external clock of the TPS65400.

TI provides an AC coupling structure as shown in Figure 8-10 when operating the TPS65400 with an external clock.

The datasheet specifies that the absolute minimum value of the clock pin RCLOCK_SYNC is -0.3V.

However, Section 8.3.5 "Clock Synchronization" explains that the clock minimum value of RCLOCK_SYNC is -0.5V when using the AC coupling structure.

-0.5V is a value that exceeds the absolute minimum.

I would like to inquire whether an external Schottky diode or a buffer structure is required.

Thanks and Best regards
Lee HongGyo

4 months ago

0 Haseen Reddy Siripi Reddy 4 months ago

TI__Mastermind 18610 points

Hi Lee HongGyo,

We will check and get back on this.

Regards,

Haseen.

0 Manish Gautam 4 months ago in reply to Haseen Reddy Siripi Reddy

TI__Genius 12180 points

Hi Lee,

No Schottky diode will be required, you can directly use the external clock.

Regards,

Manish

0 Lee HongGyo 4 months ago in reply to Manish Gautam

Intellectual 340 points

Dear Manish

Please provide a detailed explanation regarding my question.

I am curious about the following content mentioned in the question.
"The datasheet specifies that the absolute minimum value of the clock pin RCLOCK_SYNC is -0.3V.
However, Section 8.3.5 "Clock Synchronization" explains that the clock minimum value of RCLOCK_SYNC is -0.5V when using the AC coupling structure.
-0.5V is a value that exceeds the absolute minimum."

Thanks and Best regards
Lee HongGyo

0 Lee HongGyo 4 months ago in reply to Haseen Reddy Siripi Reddy

Intellectual 340 points

Dear Haseen

Please share the results of your check.

Thanks and Best regards
Lee HongGyo

0 Manish Gautam 4 months ago in reply to Lee HongGyo

TI__Genius 12180 points

Hi Lee,

In the section 8.3.5, it does not want to convey that the lower value for ROSC_SYNC pin was -0.5V. The proper meaning of that statement is the diode which they are using for safety of that pin, that diode reverse breakdown value is -0.5V.

It means if Somehow, ROSC_SYNC pin value tries to go less than -0.5V then that diode will go into breakdown and prevent that pin.

Regards,

Manish

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TPS65400: TPS65400 external clock related question