TPS82130: Question about OCP

Jayden Qiu

Part Number: TPS82130
Other Parts Discussed in Thread: TPS543320

Hi team,

This is Jayden, I have question about the OCP. The Test conditions is Vin=12V and Vout=3.3V. The waveform below is Vout.

The Vout drops when Iout=3.5A (As I calculate, ΔIL=1.196A in this condition). Then slowly increasing the Iout. When Iout=4.0A and Vout=1.8V, the 82130 shut down. Then the Vout fluctuates between 0V and 1V.

The questions are as follows:

1. The Iout=3.5A has reached the OCP, right? If so, the inductor peak current is limited to current limit. As the Iout increase, the vout decrease. If I don't increase Iout, the Vout remains constant. Is this because of power limitations?

2. 82130 shut down when Iout=4A and Vout=1.8V, Is this because of UVP? I can't find Vout UVP value in datasheet.

3. The TPS82130 do not have the hicccup. So why the Vout fluctuates between 0V and 1V after it shut down?

Thanks

Best regards

Jayden

over 2 years ago

+1 Nancy Zhang over 2 years ago

TI__Mastermind 49470 points

Hi Jayden,

1. Yes, the current limit is peak 3.5A+1.196/2=4.098A. The current limit is cycle by cycle, when the output voltage becomes lower, the peak current limit may not be reached, That is why the Vout stays there.

2. The peak current is 4+0.765/2=4.3825A, it will trigger current limit again, the high side FET turns off and low side FET turns on. If the Vout drops to below 0.5V, the current limit is reduced to 1.6A typically, then shutdown.

3. Not hiccup, just cycle by cycle current limit.

Hope this helps,

Thanks,

Nancy

0 Jayden Qiu over 2 years ago in reply to Nancy Zhang

TI__Intellectual 1405 points

Hi Nancy,

Thank for reply. This resolved my issue. But I have another two questions:

1. When 82130 reaches current limit, why not just shut down? As described above, the Vout stays there, but the Iout increase. Will it affect the load behind? Is there some special application for this design?

2. After shutdown, the high side FET and low side FET are turned off and the Vout should always be 0V，right? If the overload is removed, will it recover to normal 3.3V？

Thanks. Look forward to your reply.

BRS

Jayden

+1 Nancy Zhang over 2 years ago in reply to Jayden Qiu

TI__Mastermind 49470 points

Hi Jayden,

1. TPS82130 current limit is designed as cycle-by-cycle current limit to protect internal MOSFET and peak inductor current. This feature is benefit to some applications with inrush current. It will not shut down immediately. It will not affect the load behind.

2. Yes, if overload is removed, the device will cover to normal 3.3V.

3. You can take a look at the datasheet of TPS543320. It has hiccup OCP and UVP.

Thanks,

Nancy

0 Jayden Qiu over 2 years ago in reply to Nancy Zhang

TI__Intellectual 1405 points

Hi Nancy,

Thanks for your patient response.

BRs

Jayden

0 Zixu Wang over 2 years ago in reply to Jayden Qiu

TI__Expert 8100 points

Hi Jayden,

You are welcome. If no further question, I will close the case.

BRs

Zixu

0 Jayden Qiu over 2 years ago in reply to Zixu Wang

TI__Intellectual 1405 points

Hi Zixu,

You can close it. Thanks.

BRS

Jayden

0 Zixu Wang over 2 years ago in reply to Jayden Qiu

TI__Expert 8100 points

Hi Jayden,

Thanks for reaching out! I will close the case.

BRs

Zixu

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TPS82130: Question about OCP