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.

Abstract: A low noise battery charger includes a rectifier to convert AC line voltage to a rectified sinusoidal voltage that is applied to a primary winding of a transformer. Another rectifier coupled to a first secondary winding applies a charging current to a battery. A switch coupled in series with the primary winding controls current therein. A rectifier coupled to another secondary winding produces a battery condition voltage. An incrementing signal synchronized with the rectified sinusoidal voltage increments a ratchet DAC until its output voltage exceeds the battery condition voltage. A low charging mode signal is produced when the battery condition voltage falls a certain amount below the DAC output voltage.

Abstract: A low noise battery charger includes a rectifier to convert AC line voltage to a rectified sinusoidal voltage that is applied to a primary winding of a transformer. Another rectifier coupled to a first secondary winding applies a charging current to a battery. A switch coupled in series with the primary winding controls current therein. A rectifier coupled to another secondary winding produces a battery condition voltage. An incrementing signal synchronized with the rectified sinusoidal voltage increments a ratchet DAC until its output voltage exceeds the battery condition voltage. A low charging mode signal is produced when the battery condition voltage falls a certain amount below the DAC output voltage. Flow of current through the primary winding is controlled by operating the switch at a relatively high frequency and by producing constant turn off times for the switch and also by modulating turn on times for the switch in response to the signal indicative of primary winding current.

Abstract: A current sense amplifier includes first and second current mirrors cross-coupled to collectors of first and second transistors having a common base connection to a bias voltage circuit. First and second load devices are connected to the collectors of the first and second transistors, the emitters of which are connected to control transistors of the second and first current mirrors, respectively. The control transistors also receive first and second input currents, respectively. The collectors of the first and second transistors are connected to output terminals of the current sense amplifier.

Abstract: A low cost, high frequency isolation amplifier includes a first voltage-to-frequency converter producing a first pair of complementary pulses in response to an analog input signal and applying them to a pair of low capacitance capacitors constituting the isolation barrier. The isolation barrier differentiates edges of the first pair of pulse signals and applies the resulting signals to inputs of a sense amplifier including a differential amplifier, a pair of comparators, and a flip-flop to precisely reconstruct the first pair of complementary pulse signals, which then are fed into a decoder circuit including a phase locked loop. The phase locked loop includes a phase detector receiving the reconstructed pair of complementary pulse signals and a second pair of complementary pulse signals produced by a second voltage-to-frequency converter.

Abstract: A low cost, high frequency isolation amplifier includes a first voltage-to-frequency converter producing a first pair of complementary pulses in response to an analog input signal and applying them to a pair of low capacitance capacitors constituting the isolation barrier. The isolation barrier differentiates edges of the first pair of pulse signals and applies the resulting signals to inputs of a sense amplifier including a differential amplifier, a pair of comparators, and a flip-flop to precisely reconstruct the first pair of complementary pulse signals, which then are fed into a decoder circuit including a phase locked loop. The phase locked loop includes a phase detector receiving the reconstructed pair of complementary pulse signals and a second pair of complementary pulse signals produced by a second voltage-to-frequency converter.

Abstract: In the primary circuit of dc-to-dc converter or a dc-to-ac converter, transistor switching units are associated with two primary windings of a transformer. The transistor switching units each control the flow of current through an associated winding. The first transistor is activated by apparatus that alternatively applies and removes activation signals to the transistor and consequently allows conduction through the transistor and the associated winding. The second transistor receives activation signals from a third primary winding and causes conduction of current through the associated primary transformer winding. The activation signal from the third winding, causing the second transistor to be conductive, is the result of interruption of current in the first primary transformer winding. The activation signals produced by the third primary transformer winding is removed when the first transistor is activated and current is flows in the first primary winding.