LMK00306: Power Supply Sequence

masahiko shimizu

Part Number: LMK00306

Hi,

Could you let me know about Power Supply Sequence of Vcc and Vcco, please?
Which description below is correct?

-In datasheet page of 6
=>"(2) Vcco should be less than or equal to Vcc (Vcco ≤ Vcc)."

-In datasheet page of 20
=>"Care should be taken to ensure the Vcco voltages do not exceed the Vcc voltage to prevent turning-on the internal ESD protection circuitry"

- In datasheet page of 29
=>By below description, I think below is showed Vcc ≤ Vcco.
"Using simultaneous or ratiometric power supply sequencing prevents internal current flow from Vcc to Vcco pins that could occur when Vcc is powered before Vcco."

Best regards,
Shimizu

over 5 years ago

0 Lane Boyd over 5 years ago

TI__Genius 16845 points

This is correct: Vcco ≤ Vcc

Kind regards,
Lane Boyd

0 masahiko shimizu over 5 years ago in reply to Lane Boyd

Guru 11235 points

Hi Lane,

Thank you for your support.

If Vcc is powered before Vcco, Does internal current flow from Vcc pin to Vcco pins?
-> I think this description in datasheet(page of 29) is mistake. Is my idea correct?

Best regards,
Shimizu

0 Shawn Han over 5 years ago in reply to masahiko shimizu

TI__Genius 9920 points

Hi Shimizu,
P6, P20 describe the same thing for Vcco ≤ Vcc .
P29 solved a startup issue.

Regards,
Shawn

0 masahiko shimizu over 5 years ago in reply to Shawn Han

Guru 11235 points

Hi Shawn,

Thank you for your support.
I add questions about P29 description

Q1: How much does current flow?
Q2: Does this device have a damage when Vcc is powered before Vcco?
Q3: Is the device affected to operation when Vcc is powered before Vcco?

Best regards,
Shimizu

0 Shawn Han over 5 years ago in reply to masahiko shimizu

TI__Genius 9920 points

Hi Shimizu,
The current value depends on the gap between Vcco and 1.7V , more gap, more flow from Vcc. It could reach 200mA, device has a risk to be damaged in long time running in such situation. That's why Page 29 recommended the power supply sequencing.

If you have difficulty to control the power supply sequencing as page 29 recommended, please use LMK00301A, which has no requirement for power supply sequencing.

Regards,
Shawn

0 masahiko shimizu over 5 years ago in reply to Shawn Han

Guru 11235 points

Hi Shawn,

Thank you for your support.
I want to confirm about your answer.

When the gap between Vcco and Vcc is less then 1.7V, current doesn't flow.
Is this my understand correct?

Best regards,
Shimizu

0 Shawn Han over 5 years ago in reply to masahiko shimizu

TI__Genius 9920 points

Hi Shimizu,
No.
Vcco reaches 1.7V, the current returned to normal (not 0). If Vcco is too low, there is a high current from Vcc to Vcco.

Regards,
Shawn

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LMK00306: Power Supply Sequence