Peak voltage and peak slope detector for a battery charger circuit
First Claim
1. A peak voltage and peak slope detector circuit for a battery charger circuit comprising:
- a Voltage to Frequency Converter (VFC) responsive to a battery voltage for providing a VFC signal;
a first counter comparator responsive to said VFC for generating a pulse count of said VFC signal during a predetermined time period wherein said pulse count corresponds to a voltage magnitude of said battery voltage and wherein said pulse count is compared against a previous pulse count to determine when a peak voltage occurs; and
a timer circuit for gating said VFC signal to said first counter comparator for said predetermined time period.
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Abstract
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.
169 Citations
19 Claims
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1. A peak voltage and peak slope detector circuit for a battery charger circuit comprising:
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a Voltage to Frequency Converter (VFC) responsive to a battery voltage for providing a VFC signal; a first counter comparator responsive to said VFC for generating a pulse count of said VFC signal during a predetermined time period wherein said pulse count corresponds to a voltage magnitude of said battery voltage and wherein said pulse count is compared against a previous pulse count to determine when a peak voltage occurs; and a timer circuit for gating said VFC signal to said first counter comparator for said predetermined time period. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
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12. A peak voltage and peak slope detector circuit for a battery charger circuit comprising:
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a Voltage To Frequency Converter (VFC) having a first input coupled to a battery being charged and an output; a logic circuit having a first input coupled to said output of said VFC, a second input, and an output; a first counter comparator having a first input coupled to said output of said logic circuit, a second input, a Peak Voltage output, an Overvoltage output, and a Carry output; and a timer circuit having a first output coupled to said second input of said logic circuit, a second output coupled to said second input of said counter comparator, and a Power Down output for turning off the battery charger circuit prior to a battery voltage sampling sequence wherein said timer circuit provides a signal to said logic circuit for gating a VFC signal for a predetermined time period to said first counter comparator and wherein said first counter comparator generates a pulse count of said VFC signal during said predetermined time period, said pulse count corresponds to a voltage magnitude of said battery, said first counter comparator comparing said pulse count against a previous pulse count for determining when a voltage peak occurs. - View Dependent Claims (13, 14, 15, 16, 17)
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18. A method for detecting peak voltage and peak slope of a battery being charged, the method comprising the steps of:
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converting a battery voltage to a signal wherein a pulse count of said signal over a predetermined time period corresponds to a magnitude of said battery voltage; generating a pulse count of said signal during said predetermined time period; decrementing a previous pulse count corresponding to a previous sampled battery voltage with said signal wherein a peak voltage is detected when said previous pulse count does not reach a zero count; and providing a Carry signal indicating said battery voltage is greater than said previous sampled battery voltage when said previous pulse count is decremented below said zero count. - View Dependent Claims (19)
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Specification