-DELTAV DETECTING CIRCUIT FOR BATTERY CHARGER

摘要

PROBLEM TO BE SOLVED: To provide a -V detecting circuit which can detect the completion of the full charging of a secondary battery with high accuracy by holding the peak value of the charging voltage with high accuracy by using the down-side borrow signal of an up-down counter as a full-charging completion detecting signal. SOLUTION: A voltage comparator compares the output voltage VA of an analog adder 5 with the terminal voltage VB of a secondary battery and a gate logic circuit 7 distributes clock signals to the clock input terminal of an up counter 1 and the up-count and down-count input terminals of an up-down counter 2 based on the compared output of the comparator 6 and the up-side carry signal of the counter 2. The up-counter 1 holds the peak value of the terminal voltage VB of the battery and, when the down-side borrow signal of the counter 2 is outputted, the borrow signal is used as a full-charging completion detecting signal. Therefore, the completion of the full charging of the secondary battery can be detected with high accuracy.