TPS2HB35-Q1: TPS2HB35BQPWPRQ1 current foldback feature

Hi Scarlett,

Firstly, it is not recommended to use the device with current limit pin floating. Please let the customer know that this is a fault state of the device and it is not recommended! Please ask the customer to use Version F for highest current limit or to move to 2HB16 with an appropriate current limit resistor. Can you please ask the customer to make this change and retest it?

We also would like to see a schematic and a description of how the short is introduced. Also please ask the customer to provide waveforms that are more detailed by zooming into the initial turn off event and then the following turn off events to make sure that the peak is not being missed due to sampling.

Thanks,

Shreyas

Hi Shreyas

1. Datasheet description is Rlim GND, open or out of range. Is it not recommended for all these configs or just not recommended left floating?

2. Please see below waveforms ( C3 is the current, UBR is power supply 12V)

The total shutoff procedure 

the first shutoff, 29A

The second shutoff, 16A

Thank you

Scarlett

Hi Scarlett,

Thank you for the new scopeshots. This helps a bit but can you ask the customer to provide a schematic and a description of the test? How is the short circuit performed on the device?

Please let the customer know that using the ILIM pin in any setting of ILIM=GND, out of rang or floating is the same thing for the device and this setting is not allowed for the device. This is a fault state of the device that is only meant to be used if the RILIM resistance fails. 

Thanks,

Shreyas

Hi Shreyas, 

Thank you, customer has tried use Rlimit resistor and there's foldback after 7 retry. The new question is, it only happens with first enable. When the short circuit happens another time, there's no 7 times retry then foldback. Could you help explain why?

Thanks

Scarlett

Hi Shreyas, 

This figure shows the overcurrent phenomenon after the chip is first enabled through EN

This figure shows the phenomenon of the chip experiencing an overcurrent fault once and then overcurrent again without being enabled through EN again

The LATCH pin is always low, but it can be seen whether re enabling has a different impact on the overcurrent phenomenon of the chip.

Jiaojiao,

As Shreyas mentioned, we really need a schematic of how the TPS2HB35-Q1 device is setup to understand the issue and help isolate the problem. If you do not want to post it on E2E, please just email it to Scarlett and she will be able to it it to us. 

In this test setup, could you comment on how the short-to-ground is being introduced into a system? Is there some sort of relay setup, or is it going through some sort of eLoad? Somewhat related note, but keep in mind that for our automotive devices we test the output conditions to AEC-Q100-012 with an impedance of 100mOhm 5uH on the output short condition.

I am double checking on the LATCH functionality with the backend team and will update shortly.

Best Regards,
Tim

Hi，Shreyas：

Thank you for your reply, it's very helpful.

I would like to confirm again that as long as the LATCH pin status is low, the chip can automatically restart. However, to achieve the function of halving the 7x current limits , we need to lower the EN pin again and then raise it again.

Thanks,

Jiaojiao