TPS2662: Looking for Adjustable Current Limit that can be Changed

Hello George

TPS2662x current limit can changed by changing pull down resistor value on ILIM pin.

If you refer to TPS26624-25 EVM (https://www.ti.com/lit/ug/slvuba5/slvuba5.pdf) , then you can see that we have given a provision for changing current limit setting from 25mA to 880mA. If it is possible to change this resistor setting in your final setting manually then this can be one of the options.

If manual intervention is not possible in your final test solution then digital potentiometer can be another option to switch between two current limits.

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Thanks

Abhijeet

Hello Abhijeet,

I need/want something that can be automated so manual changing of the ILIM resistor is not a good solution for me. A digital potentiometer would also not work because I need to start with the lowest current setting and then progress to the maximum and I don't think there's a pot with 75kΩ to 250kΩ range.

One other issue that I wasn't thinking about is that my system is using 24VAC so this part wouldn't work with AC and I'm not sure there is a part that works with AC. I could potential change to using 24VDC but since the production board will be used in HVAC application it will have 24VAC as it's power source so I prefer to test under the same conditions.

George

Hi George

Thanks for explaining your use case.

Another option I could think of is using 2 channel analog switch / Mux to switch between two current limits. You can go for a respective current limit resistor with a low side switch connecting them to GND.

For 24V AC use case, TPS2662x will block the input voltage during negative half cycle of 24V AC. So output voltage will drop during this time. So ideally rectifier followed by TPS2662x looks to be a solution if you want to provide both 24V AC nd 24V DC support

Please click "This resolved my issue" button if this post answers your question

Thanks & Regards

Abhijeet

Hi Abhijeet,

Yes, I have thought of using either an analog switch or even a MOSFET controlled parallel resistor on the ILIM pin. If I design in the TPS2662 I probably would just switch to powering everything with 24VDC. That's not exactly what I want to do but I'm not finding any good AC solutions. I'm also somewhat concerned that 25mA is not low enough to prevent any damage to the DUT if it does have a short. I was almost expecting to find something that could detect a short circuit but I haven't really found that for some reason.

Why is the EVM for the TPS2662 so expensive?

Thanks,

George

Hi George

TPS2662x EVM allows user to evaluate two out six orderable parts using one EVM. For example

1. TPS26620-23EVM has TPS26620 and TPS26623 and required configuration circuit for each device on one EVM.  

2. TPS26624-25EVM has TPS26624 and TPS26625 and required configuration circuit for each device on one EVM.   

This gives user flexibility to perform various tests based on the end application needs. 

Please click "This resolved my issue" button if this post answers your question

Thanks & Regards

Abhijeet

Hi Abhijeet,

Thank you again for your help in trying to find a solution for my product. In the end, unfortunately, I could not find a suitable part from TI. I found the OnSemi NCV47822 which is a dual current limit switch which can go as low as 10mA. With this switch I can set one switch to 10mA and then the 2nd switch can have the higher current limit after I have confirmed that the DUT does not have any shorts. It doesn't offer the protection that the TPS2662 offers so I may have to add something after this part for full protection.

Best Regards,

George