LTC4124 charge complete behavior


LTC4124 datasheet page 10 says “After the 3-hour charge termination time expires, charging stops completely”, but does not clarify what it means:

Does it mean the ACIN input (resonant tank) is being grounded?

Does it mean the CHRG led is to go off?

I have seen it continues taking power from transmitter even after several hours, so it seems the ACIN is never grounded. Why not? if charging is off.

I have also seen the led remains ON (no blinking) forever.

If it is the normal behavior, it does not make much sense for me:

in my particular implementation the transmitter is also battery powered and takes 5mA at idle (no RX coil coupled) and 55mA when RX coil is coupled EVEN AT CHARGING COMPLETE STAGE. It is too much power just for nothing.

From my point of view, a “charging stops completely” should also include ACIN grounded and led to go off (CHRG high impedance). My doubt is if it is so and I have something wrong at my setup.

Thank you,

Alberto Farre