Abstract: A system and method for battery isolation in a charging system includes an isolation diode connected to a charger input voltage and a PNP pass transistor connected in series between the isolation diode and a battery. The pass device conducts a charging current in response to a drive signal applied to its base; the pass transistor side of the diode is at a voltage Vchg. A first switch couples the pass transistor's base to Vchg when Vchg>Vbat such that the pass transistor's base-collector junction blocks current from Vchg from flowing through the pass transistor when the charger is not in use, and a second switch couples the base to Vbat when Vbat>Vchg such that the pass transistor's base-emitter junction blocks current from the battery from flowing through the pass transistor when the charger is not in use.

Abstract: A programmable temperature detector for simple detection applications is described. The programmable temperature detector has three terminals and a plurality of temperature-transitions points from which to choose. A first terminal receives power from a supply, a second terminal receives a ground reference, and a third terminal provides an indication of an object's temperature crossing a selected temperature-transition point. The desired temperature transition point is specified by a single non-precision resistor coupled in series with the power terminal of the detector. The non-precision resistor and a power supply set a program signal, in the form of a current, into the power terminal of the detector. The programmable temperature detector comprises circuitry for quantizing the program signal into a discrete signal level and for selecting a temperature transition point in response.