TPS82130: TPS82130 PG behaviour

FRA51029

Part Number: TPS82130

Hi,

One of my customers sent me an electronic board that was stuck in reset. After investigation, I found that the reset cause is a TPS82130.

I use a TPS82130 to produce a +3.3 V voltage (1.2 A) from a +12.0V voltage.

See picture below:

The PG output is used as reset source on my electronic board.

My issue is that the TPS82130 seems to start normally, but its PG output has a strange behaviour, causing burst of resets.

Here is what I see (PG output is no more connected to the rest of devices, except to the pull-up resistor).

CH1 is Enable input of TPS82130.

CH2 is Vout of TPS82130 (3.3V).

CH3 is PG output of TPS82130.

At the end of the Vout ramp, the PG signal leaves the 0V level for a 0.68V level, and ~2ms after reaches 3.3V and then falls to 0.68V.

PG voltage never goes to 0V (signalling a default), but does not keep a 3.3V level.

The Vout voltage is stable. If I don't use the PG as reset source, my electronic board behaves normally.

Do you have an explanation for the behaviour of the PG pin ?

I use many TPS82130 on my board without problem (I even have a second one that also produces a 3.3V supply from the same +12.0V input without problem).

Best regards,

Fred.

over 1 year ago

0 Tahar Allag over 1 year ago

TI__Mastermind 28680 points

Hello,

it looks like the PG is no longer pulling down and that how it is expected to behave, it looks like the AUX 3.3 is not able to pull it high.

Try to increase the pull up from 10K to 100Kohms.

Thanks

Tahar

0 Nancy Zhang over 1 year ago in reply to Tahar Allag

TI__Mastermind 45820 points

Hi,

I agree with Tahar.

1. Could you probe 3V3 Aux to see if it has same behavior?

2. Please try PG pull up to 3V3 to instead of 3V3 Aux.

Hope this helps,

Thanks,

Nancy

0 FRA51029 over 1 year ago in reply to Nancy Zhang

Prodigy 70 points

Hi Nancy,

I checked the 3V3aux and the voltage is stable at +3.3V. No problem with this power supply.

I pull up the PG to 3V3 (Vout of TPS82130) instead of 3V3aux, but the behaviour is still the same as shown on the following screenshot:

CH1 is Enable input of TPS82130.

CH2 is Vout of TPS82130 (3.3V).

CH3 is PG output of TPS82130, pull-up with 10kOhm to Vout.

Fred.

0 Tahar Allag over 1 year ago in reply to FRA51029

TI__Mastermind 28680 points

did you try 100K pull up instead?

0 FRA51029 over 1 year ago in reply to Tahar Allag

Prodigy 70 points

Yes, I try 100k but no improvment:

CH1 is Enable input of TPS82130.

CH3 is Vout of TPS82130 (3.3V).

CH2 is PG output of TPS82130, pull-up with 100kOhm to Vout.

With 100k pull-up the PG voltage oscillates between 0.08V and 3.3V. Whereas with 10k pull-up the PG voltage was oscillating between 0.68V and 3.3V.

Could the device be damaged ?

0 Tahar Allag over 1 year ago in reply to FRA51029

TI__Mastermind 28680 points

Hello Fred,

The Power Good function is an open drain, pin goes high impedance once the output is above 95% of the nominal voltage, and is driven low once the output voltage falls below typically 90% of the nominal voltage.

So if toggling like this, I suggest either:

The the pull up you are using is not able to pull up the PG pin or
the VOUT is not regulated well and goes out of regulations and PG start toggling. I do see VOUT is stable from your plot
the device is damaged

try to use another device. and see if the that helps

Thanks

Tahar

0 FRA51029 over 1 year ago in reply to Tahar Allag

Prodigy 70 points

Hello Tahar,

I will try another device.

Fred.

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TPS82130: TPS82130 PG behaviour