LT3650 Status Pins' Pull Up Voltage.

Hello All,

I am using a LT3650-8.4 Polymer Li-Ion battery charger for two cells. The IC run well when the pull up voltage

at the status pins /SHDN, /FAULT, and /CHRG is the same as the input voltage Vin.

According to the datasheet, /FAULT and /CHRG are open collector pins, so should be possible to drive  these pins

at a lower voltage,  such as +3.3VDC with the purpose of interfacing to logic.

However, when these pins (all of them, or only these two with /SHDN = Vin) are driven at +3.3VDC, the current consumption

doubles after a minute or so, after it started charging the battery. This immediately leads to potentially destructive overheating

of the device.

When all the pins are pulled up at Vin, this phenomenon does not happen and the charge process completes successfully.

There is no information in the datasheet about driving this pins any voltage below Vin. Why is not possible if these are open collectors?

There is any issue at silicon level?

Thanks.