In the circuit above, 3 of 5 prototype boards fully charge the battery (determined by 0.00 v drop across the PTC) and yet the CHG- pin never goes high (i.e. is always low). nCURRENT_ISET is set low and CHRGR_EN is FLOATING ISET max is 300 mA. The resistance of the PTC is 0.4R. There is minimal noise on the pins. Do you have any ideas what could be causing this problem? The battery is a Tenergy14500 800 mAH.