TPS274160: Minimum Current programming/limit

Antenna_Head

Part Number: TPS274160

The datasheet for TPS274160 mentions that the lower bound of the current limit is 250 mA.

We're working on an implementation that requires a much lower limit so that the load can be probed. Due to a connector issue, the load on the cable attached to TPS274160 could be connected backwards. The idea is to use a very low current limit on TPS274160 to strobe the load to see if it is plugged in correctly.

The do this properly, a very low current needs to be used to avoid damaging the load (an FPGA). Something on the order of a few 10's of mA should be OK. An ADC or comparator will check the load voltage when strobed to determine the position of the load.

What is the minimum possible current that can be reliably set? Understood that the accuracy will suffer- an accurate current isn't required, just that it be reproducible and low.
Is it OK to use an analog switch or FET to dynamically change the current limit via the programming resistor?

Thanks!

-Steve

4 months ago

0 Alex Bhandari-Young 4 months ago

TI__Mastermind 26345 points

Hi,

We will get back on this early next week

Best,

Alex

0 Filip Rados 4 months ago in reply to Alex Bhandari-Young

TI__Expert 6460 points

Hi Steve,

I will have to take a look at this tomorrow (3/17).

Thanks,

Filip

0 Filip Rados 4 months ago in reply to Filip Rados

TI__Expert 6460 points

Hi Steve,

Using an analog switch/ FET to change the current limit is fine. I'll check internally to find the minimum current limit, regardless of accuracy.

Thanks,

Filip

0 Filip Rados 4 months ago in reply to Filip Rados

TI__Expert 6460 points

Hi Steve,

I am still looking internally.

Thanks,

Filip

0 Antenna_Head 4 months ago in reply to Filip Rados

TI__Genius 13580 points

Thanks, I appreciate the updates.

0 Filip Rados 4 months ago in reply to Antenna_Head

TI__Expert 6460 points

Hi Steve,

I apologize for the delay. Our team in India is on holiday today (3/19).

Thanks,

Filip

0 Filip Rados 4 months ago in reply to Filip Rados

TI__Expert 6460 points

Hi Steve,

As a reference, using a 20kOhm resistor would give an ICL of 100mA at ~+/- 50% accuracy.

Technically, you can use a 200kOhm resistor to get an ICL of 10mA, but the accuracy will easily be above ~+/- 50%.

If this amount of inaccuracy is okay, then feel free to use a large RCL to minimize the strobe current.

Additionally, I would recommend using a well-regulated supply to adjust the current going into the TPS274160. Current limiting is more for protection rather than control. Otherwise, the current difference will be absorbed by the device, and it could heat up dramatically. Granted, short pulses to confirm a connection should be okay, so long as the device is not held at this low current limit for an extended period of time.

Thanks,

Filip

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TPS274160: Minimum Current programming/limit