Peak voltage and peak slope detector for a battery charger circuit

摘要

A peak voltage and peak slope detector circuit (41) of high resolution is disclosed for sensing a battery voltage during a battery charging sequence. Battery charging circuitry is disabled when a battery voltage is being sampled to eliminate error due to noise. The battery voltage is sampled at predetermined intervals for a predetermined time period which is determined by a sample timer (46). A Voltage To Frequency Converter (42) converts the battery voltage to a signal. The signal frequency corresponds to the magnitude of the battery voltage. The number of pulses output by the VFC (42) are counted during the predetermined time period. The number of pulses are counted and compared against a previous sample by a counter comparator (44) to determine peak voltage. The peak voltage occurs when the sampled count is less than the previous sample count. The rate of change of the battery voltage is monitored by a second counter comparator (47) for determining peak slope during the battery charging sequence.