TPS2HB16-Q1: Datasheet only provide maximum current limit When R ILIM = GND, open, or out of range.

Thanks for your reply.

If I use internal current limit as primary current limit, what's your concern?

I think the internal current limit is same as external resistance limit, just a comparator input.

Why you don't suggest this application?

Thanks for your reply again~

Ling,

We just do not specify the internal current limit as for the devices with the ILIM pin one of the features is to set the current limit to a custom limit that is closer to your nominal load profile. We do offer the F version of the device that does not have a current limit pin, however has the MIN/MAX specified.

Would you be able to comment on what your nominal load current is as well as what the current limit is required to be? From there- I can suggest an appropriate part.

Best Regards,
Tim

Hi Tim

Thanks for your reply.

This is my loads inrush current & normal current.

Ling,

Allow me some time to get the right loads for the list- I should have something within a day or so.

One thing I did want to mention is that for the HBxx devices, with the exception of the C variants, are all immediate shutoff for the current limit. This means that when the current limit is hit, the device shuts off immediately and would not be suitable for prolonged inrush.

Best Regards,
Tim

Hi Tim

1. I want use internal current limit as primary current limit. I will open limit resistance，but I concern floating PIN will suffer from external interference.

2. For your comments before, you did not descripte clearly what risk will occurr if I use. Can you give me more evidence？

3. I want to know the minimum current limit value when R ILIM = GND, open, or out of range.

Add more information，I will use SNS to get output current realtime through MCU，if  overcurrent occurred， MCU will close this channel.

Ling,

If the current limit resistor cannot be used in the design, the recommendation is to use the F version of the device that has a set internal current limit and repurposes the ILIM pin as a general purpose fault pin. For the F version, we specify the min/max:

TPS2HB16-Q1:

To answer your questions below:

1. The only way that this would be an issue is if there was significant impedance between ILIM and VBB. This is the normal path of the ILIM resistor. Anything else on the line would just be treated as open or out-of-range and the typical value would apply. With the F version, however, the pin is bonded differently and there would be no risk of interference. 
2. There is not explicit risk to the design- it's just the only thing we guarantee in this use case is that the high-side switch will shut down and not be damaged. I checked the backend data and we don't have minimum/maximum values (see #3)
3. Not populating the ILIM pin on an A/B version of the device is considered a failure condition as the "open or out of range" on these devices is not referring to a deliberate design decision, but rather a fault situation where the resistor that is connected to ILIM is damaged/shorted.

Best Regards,
Tim

Thanks for your reply. your comments is very useful.

1. If I open limit resistance，PIN ILIM1 & ILIM2 will floating. There is not significant impedance between ILIM and VBB，my concern is external interference such as EMC.

2. OK

3. I prefer use version A/B，version F‘s limit current is too large.

If I use  version A/B，your datasheet shows Rlimit must >5K，if I use 3.3K or 4.7K，what will happen？and how to define out of range？

Ling,

First, we have the following tool for our HBxx/HAxx family which will show you the min/max current limits for all of the devices and also account for things like resistor tolerance. This might be useful for you. 

https://www.ti.com/tool/download/SLVRBG2

For the EMC question, as long as you have the recommended bypass capacitors on  the input/output you will have optimal EMC performance. For the HBxx device family, this is:

If there is no resistor/diode network on ground- just connect to the same ground.

For the ILIM resistors out of range- there is a point where the device will assume that there is an open or short condition and default to the internal current limit as a failsafe. Generally, what the guidance is to pick an RON device and A/B/F variant that matches your load current. For example, if you cannot set the current limit high enough on the TPS2HB16-Q1 which is a 16mohm device, the recommendation would be to move to the 8mohm TPS1HB08-Q1 which would be able to set higher current limits.

Best Regards,
Tim

Thanks for your reply. I still have some confuse.

You mean R ILIM = GND, open, or out of range just avoid resistance damaged by accident？

If I use Rlimit=3.3K，it calculate limit current is 24.4~41.9A，but your datasheet show Rlimit must >5K.

I want to know if I use Rlimit<5K，such as 3.3K，does it limit feature work normally？If yes, I want to know which limit value will be triggered，external resistance setting limit or internal limit?

add another question.

Does ILIM1 ILIM2 have internal resistance？if yes，is it pull down resistance or  pull up resistance？

Got it.