Abstract: The teachings presented herein provide a method and apparatus for operating constant on-time DC/DC converters, including pseudo constant on-time variants, with a virtual current-mode slope signal. Use of the slope signal provides, among other advantages and improvements, greater noise immunity and the ability to operate with a wider range of converter output filters. More particularly, incorporating a properly synchronized slope signal into the on-time triggering comparison provides for a maximum slope offset at on-time triggering. Doing so prevent double-pulsing (i.e., erroneous on-time retriggering) and other undesirable behavior of conventional constant on-time DC/DC converters and, as a particular but non-limiting advantage, allows ready and advantageous use of the slope-compensated converter as taught herein with low ESR capacitors in the output filter.

Abstract: The teachings presented herein provide a method and apparatus for operating constant on-time DC/DC converters, including pseudo constant on-time variants, with a virtual current-mode slope signal. Use of the slope signal provides, among other advantages and improvements, greater noise immunity and the ability to operate with a wider range of converter output filters. More particularly, incorporating a properly synchronized slope signal into the on-time triggering comparison provides for a maximum slope offset at on-time triggering. Doing so prevent double-pulsing (i.e., erroneous on-time retriggering) and other undesirable behavior of conventional constant on-time DC/DC converters and, as a particular but non-limiting advantage, allows ready and advantageous use of the slope-compensated converter as taught herein with low ESR capacitors in the output filter.

Abstract: In a switched mode power supply (SMPS) that regulates an output voltage in response to load conditions by switching an inductor circuit between a supply voltage and ground at a switching frequency, under light loading conditions, the switching frequency of the SMPS is reduced down to a variable minimum switching frequency sufficiently high to avoid audible noise generation.

Abstract: In a switched mode power supply (SMPS) then selectively operates in continuous current mode (CCM) and discontinuous current mode (DCM), the minimum switching frequency of the SMPS is adjusted by setting a minimum duration for DCM operation. A resistance value applied to an external pin of the SMPS controls the duration of a timer that is reset in CCM and activated upon entering DCM. Upon expiration of the variable duration, the SMPS reverts to CCM for at least one switching cycle. This allows the SMPS minimum effective switching frequency to be set, for each application in which the SMPS is deployed, at a level that avoids audible noise (but which may be lower than an ultrasonic frequency), thus taking maximum advantage of the efficiencies of DCM operation under light load conditions.

Abstract: In a switched mode power supply (SMPS) then selectively operates in continuous current mode (CCM) and discontinuous current mode (DCM), the minimum switching frequency of the SMPS is adjusted by setting a minimum duration for DCM operation. A resistance value applied to an external pin of the SMPS controls the duration of a timer that is reset in CCM and activated upon entering DCM. Upon expiration of the variable duration, the SMPS reverts to CCM for at least one switching cycle. This allows the SMPS minimum effective switching frequency to be set, for each application in which the SMPS is deployed, at a level that avoids audible noise (but which may be lower than an ultrasonic frequency), thus taking maximum advantage of the efficiencies of DCM operation under light load conditions.

Abstract: A battery charging circuit senses charging current using a sense circuit that includes a time-averaging amplifier circuit that nulls amplifier offset errors from the sensed current signal. With such offset correction, the sense circuit provides accurate current sensing over a wide dynamic range of charging current and thus may be used for low and high charging currents, and accurate detection of trickle and end-of-charge currents. The substantial elimination of amplifier-offset errors from charging current sensing permits use of a single sense resistor over a wide range of charging currents. Such accurate current detection supports zero-current regulation of the battery, which allows the battery to remain connected to the charging circuit even after reaching its end-of-charge condition. The battery charging circuit further may include digital switchover circuitry, which reduces charging control discontinuities by allowing both current and voltage feedback loops to drive the same regulation control circuit.

Abstract: A battery charging circuit senses charging current using a sense circuit that includes a time-averaging amplifier circuit that nulls amplifier offset errors from the sensed current signal. With such offset correction, the sense circuit provides accurate current sensing over a wide dynamic range of charging current and thus may be used for low and high charging currents, and accurate detection of trickle and end-of-charge currents. The substantial elimination of amplifier-offset errors from charging current sensing permits use of a single sense resistor over a wide range of charging currents. Such accurate current detection supports zero-current regulation of the battery, which allows the battery to remain connected to the charging circuit even after reaching its end-of-charge condition. The battery charging circuit further may include digital switchover circuitry, which reduces charging control discontinuities by allowing both current and voltage feedback loops to drive the same regulation control circuit.