TPS92692-Q1: GATE-pin handling when VIN=OFF

Yuto Kitamura

Part Number: TPS92692-Q1

Tool/software:

Hi team,

I are turning off VIN with high side switch to minimize the current consumption. But I am concerning about Qm and Gate-pin status when IC is off. It may be undefined, so I think Gate-source resistor will be needed. It is not placed usually but my case it may need. But I am concerning if it affect boost circuit because it will be connected IS-pin.

Please give me your comment.

We are adding the resistor for Qdim alredy as we got advise on e2e before.

Best regards,
Yuto Kitamura

over 1 year ago

0 Daniel Louis over 1 year ago

TI__Expert 6170 points

Hello Yuto,

I do not recommend powering this device with a high side switch as it will need to be synchronized properly with the control signals to ensure power is delivered effectively when the converter needs it. If an external switch is not properly controlled , it could cause irregular operation of the converter, leading to efficiency loss or potential damage

Best,
Daniel

0 Yuto Kitamura over 1 year ago in reply to Daniel Louis

TI__Expert 6905 points

Hi Daniel,

We are considering this configuration based on the internal e2e below.

https://e2e.ti.com/support/power-management-group/power-management---internal/f/power-management---internal-forum/1358737/tps92692-q1-current-consumption-in-shutdown-mode?tisearch=e2e-sitesearch&keymatch=tps92692-q1#

We will handle the power-on timing properly and make sure it will not cause irregularity.

Please give us the comments on Qm Gate handling.

Best regards,
Yuto Kitamura

0 Yuto Kitamura over 1 year ago in reply to Yuto Kitamura

TI__Expert 6905 points

Additional comments on my side, that we confirmed if the resistor is placed, the circuit does not work properly. and it causes OVP and hiccup operation.
Even we do not place the resistor, PDRV was around 12V and can operate as expected. Therefore we think we do not need the additional resistor. Please give me your thoughts.

Waiting for your update.

Thank you.

0 Daniel Louis over 1 year ago

TI__Expert 6170 points

Hi Yuto, that is correct: attaching that resistor will disrupt the normal operation of the converter, as the current sensing will be inaccurate when that resistor is placed between the GATE and IS pins

0 Yuto Kitamura over 1 year ago in reply to Daniel Louis

TI__Expert 6905 points

Hi Daniel,

Let me correct some information.

They found the hiccup operation by adding R2 in the image below. Would you please give me the comment?

1. Is R2 needed? -> customer found unappropriated behavior.

2. Is R1 needed? -> you mentioned it may cause in accurate CS.

best regards,
yuto

0 Daniel Louis over 1 year ago in reply to Yuto Kitamura

TI__Expert 6170 points

At the beginning of this post, you do not have R2 in the schematic. When did this change? You are sending me a different schematic then originally posted

0 Daniel Louis over 1 year ago in reply to Yuto Kitamura

TI__Expert 6170 points

To answer your question, R2 can adversely affect current sensing

R1 can also affect switch current sensing

0 Yuto Kitamura over 1 year ago in reply to Daniel Louis

TI__Expert 6905 points

Hi Daniel,

How about the case when R1 is pulled down to GND, not IS-pin. Do you think it will be the problem?

Best regards,
Yuto Kitamura

+1 Daniel Louis over 1 year ago in reply to Yuto Kitamura

TI__Expert 6170 points

Hi Yuto,

If you intend to turn off VIN with a HSS, please place it BEFORE the capacitor as it will help you avoid unnecessary transients at the input of the inductor.
Also, you are more than welcome to tie R1 to GND, however, this is only useful in the event of a fault as this device already produces a known value at the gate pin.

Best,
Daniel

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TPS92692-Q1: GATE-pin handling when VIN=OFF