TPS659037: VRTC of TPS659037 use for GPIO7(POWER HOLD)

KOKI NISHIBU

Prodigy 10 points

Part Number: TPS659037
Other Parts Discussed in Thread: AM5746

Hi,

I have a question and can't resolve.

We used TPS659037(PMIC) for AM5746 in our created the circuit board.

This PMIC has a power hold function, and this function is assigned to GPIO7.

So, we tie LDOOUT_VRTC(1.8V) to GPIO7, Reset in, nSLEEP, Boot1 through 10kΩ Pullup resister.

"issue point"

However, the voltage level of the output VRTC exceeds the maximum value.

This case, voltage value of output VRTC is about 1.95V.

But, VRTC output maximum range is 1.85V.

"question"

Maximum range of VRTC output is real 1.85V ?

If this range is upper 1.85V, what is issue for PMIC.

VRTC is used only pullup for PMIC secondary function pin.

Therefore, the value of VRTC cannot be adjusted.

We think mistake in datasheet of this PMIC or PMIC has any issue.

Best regured,

Koki Nishibu

9 months ago

0 KOKI NISHIBU 9 months ago

Prodigy 10 points

I have second question.

Can be disable Power-Hold function ?

We think, If the power hold function is disabled GPIO7 does not need to be connected to VRTC.

So, we below set resister and circuit.

# smps_powergood_mask2 resister bit 2 : 0 (※GPIO_7 line is enabled)

# GPIO7:GPIO output mode (primary function)

# GPIO7:internal pullup is disable

# GPIO7 pin is tied to VRTC (1.8V)

But, PMIC is shutdown.

0 Phil Yi40 9 months ago in reply to KOKI NISHIBU

TI__Mastermind 35620 points

Hi Nishibu-san,

Please refer to the UG linked here for answers to your questions.

Thanks!

Phil

0 KOKI NISHIBU 9 months ago in reply to Phil Yi40

Prodigy 10 points

Hi Phil-san,

Thanks for the comment.

However, we did not find the best answer to our question.

So, we would change the way we ask the question.

・Can the voltage on LDOVTRC exceed 1.85V even though "LDOVRTC_OUT" is connected only to this PMIC (GPIO7, Reset In, nSLEEP, Boot1 through a 10kΩ pull-up resistor) ?

In the above case, the LDOVTRC voltage is 1.95 V on my circuit.

0 Phil Yi40 9 months ago in reply to KOKI NISHIBU

TI__Mastermind 35620 points

Hi Nishibu-san,

If any pin of this PMIC (GPIO7, Reset In, nSLEEP and Boot1) through a 10kΩ pull-up resistor pulled up >1.8V can cause LDOVRTC exceed 1.85V since the LDOVRTC output can source current only no sinking current at all.

Thanks!

Phil

0 KOKI NISHIBU 9 months ago in reply to Phil Yi40

Prodigy 10 points

Hi Phil-san

Thanks your replay.

I have add a question.

If voltage on LDOVRTC exceed 1.85V, any issue or effect for LDOVRTC_OUT ?

LDOVRTC_OUT breakdown electrical isolation ?

I think the PMIC function pins (e.g. GPIO7) are 5.25V tolerant, so there should be no problem if the LDOVRTC voltage exceeds 1.85V.

Best regured,

0 Phil Yi40 9 months ago in reply to KOKI NISHIBU

TI__Mastermind 35620 points

Hi Koki-san,

It's better to keep the LDOVRTC output voltage not exceeding 1.85V. Can you please try to follow the UG as showing by picture below?

Thanks!

Phil

0 KOKI NISHIBU 9 months ago in reply to Phil Yi40

Prodigy 10 points

Hi Phil-san

What is the name of the pmic internal module that outputs Vdds1v8?

I referred to the same explanation when designing the circuit.

But another design documents are described that GPIO7 is tied VRTC.

And VRTC voltage is1.8V on data sheet typical , so I tied gpio7 to VRTC

I'm confused

0 Phil Yi40 9 months ago in reply to KOKI NISHIBU

TI__Mastermind 35620 points

Hi Koki-san,

I found the VRTC is 5.25V tolerance from attached design checklist.

TPS659037 Design Checklist Revision B.xlsm

Thanks!

Phil

0 KOKI NISHIBU 9 months ago in reply to Phil Yi40

Prodigy 10 points

Hi Phil san

I checked your found checklist.

LEVEL column is described below
2.5-5.25 during on mode

Since there is a 5.25V tolerant at this level, does this mean that the output of the VRTC can exceed 1.8V?

0 Phil Yi40 9 months ago in reply to KOKI NISHIBU

TI__Mastermind 35620 points

Hi Koki-san,

Yes; the output of the VRTC can exceed 1.8V and it's safe no damage until >5.25V.

Thanks!

Phil

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TPS659037: VRTC of TPS659037 use for GPIO7(POWER HOLD)