초록 ▼

A battery protection circuit includes a moisture detection circuit, a temperature sensing circuit, and a high-temperature battery discharge circuit. The moisture detection circuit includes a pair of conductive traces closely spaced on a substrate such that a resistive path is formed between the trac

A battery protection circuit includes a moisture detection circuit, a temperature sensing circuit, and a high-temperature battery discharge circuit. The moisture detection circuit includes a pair of conductive traces closely spaced on a substrate such that a resistive path is formed between the traces when moisture forms on the substrate. The traces are connected between the positive battery terminal and a pull-down current source. When moisture forms on the substrate, pull-up current flows between the traces, and a resulting voltage change on one of the traces is detected by circuit element such as a logic inverter. The temperature sensing circuit includes a voltage reference circuit that generates a proportional-to-temperature voltage and temperature-independent voltage reference signals corresponding to various predetermined temperatures. A measuring circuit operates during a sampling interval to compare each temperature-dependent voltage to the proportional-to-temperature voltage and to store the result of each comparison until a subsequent temperature sampling interval. The measuring circuit includes multiplexing circuitry used to sequentially select each temperature-dependent voltage during a sampling interval. The high-temperature discharge circuit connects a discharge load across the battery when the voltage of the battery is above a high voltage threshold and the temperature of the battery is above the high temperature threshold. When no external charger is active, the discharge current flowing through this load works to reduce battery voltage. helping to prolong battery life.

대표청구항 ▼

1. A moisture detection circuit, comprising:a substrate having a reference conductor and a sense conductor formed thereon, the conductors being closely spaced apart such that exposure of the substrate to moisture causes formation of a conductive path carrying a sense current between the conductors w

1. A moisture detection circuit, comprising:a substrate having a reference conductor and a sense conductor formed thereon, the conductors being closely spaced apart such that exposure of the substrate to moisture causes formation of a conductive path carrying a sense current between the conductors when the voltage between the conductors is on the order of a circuit operating voltage; a voltage source coupled between the reference conductor and a reference circuit node to provide substantially the circuit operating voltage therebetween; a current source coupled between the sense conductor and the reference circuit node, the current source generating a bias current sufficient to maintain a first voltage on the sense conductor in the absence of the sense current and to permit the sense conductor to be driven to a second voltage in the presence of the sense current; and a voltage detection component coupled to the sense conductor, the voltage detection component being operative to discriminate between the first and second voltages so as to generate a binary output signal indicating whether the substrate is exposed to moisture.