We use the PDM to switch a lot of LED's and would like an undercurrent warning for blown LED.
Would it be possible to have a feedback setting for the PDM so that can measure 10- 100 mA. It seems to only detect currents over 400 mA.

The FETs used to control the outputs on the PDM are set to high current mode, which according to their datasheet means the typical low end of current detection is ~500mA. The absolute minimum according to the datasheet would be 200mA, so your report of 400mA is right in the expected range.

Even if the FET current detection was sensitive enough, the communication specification details a minimum of 125mA for the current feedback message. This is because the current feedback value is contained in a single byte, and it needs to be able to cover the full current range for the output. This limits the current feedback resolution to 125mA per bit.

It doesn't seem like the PDM's current detection is sensitive enough for this application, as it's more suited to high-current applications.

Thank you

Joe
thanks for the detailed reply. Would it be possible to drive the FET in a low current mode?.., reduce the current range by 10% then the feedback range could be 12. mA increments ?
I do realise the PDM is design for more high current uses . but there is an increasingly large amount of LED being used and think it would be a welcome feature.

At this time, it is not possible to place the output FETs into low current mode at runtime. This would require both a PDM firmware and PowerVision software change.

According to the datasheet for our FETs, when they are in low-current mode the minimum detectable current would typically be 7mA, but the current measurement is relatively inaccurate (+/-30%) in this mode. Also, the maximum continuous current would be reduced from 15A to 5A.

We've added this feature to our request list. I'll PM you contact details for further discussion.

Thank you