Abstract: A signal isolator circuit employing a pulse transformer overcomes the disadvantages of both prior art opto-coupler and pulse transformer signal isolator circuits by employing an active signal retrieval circuit which, in a higher accuracy configuration, repetitively performs the following steps on the electrical side of the pulse transformer where the signal information is required: 1) drives a current pulse into the pulse transformer; 2) samples or detects the voltage across the pulse transformer after it has been stabilized; 3) holds or stores the sampled voltage for a full cycle of operation; and, if necessary, 4) filters the sampled signal. On the other electrical side of the pulse transformer, the retrieval circuitry is configured such that when the pulse transformer is being driven by the current pulse, the voltage will be clamped by the source signal reset.

Abstract: A MOSFET driver integrated circuit or other peripheral circuit interfaced to a controller that operates on the primary side of a DC to DC converter having a high input voltage relative to the supply voltage powering both the controller and the MOSFET driver or other peripheral circuit is controlled by an under-voltage lockout circuit to transition from a standby mode to a normal operating mode of the MOSFET driver or other peripheral circuit only when the supply voltage is sufficient to sustain normal operation and the driver or other peripheral circuit senses activity at an input that indicates that the controller has previously transitioned from a standby mode to a normal operating mode.

Abstract: A controller for a two-switch buck-boost converter accomplishes one-at-a-time switch control by simultaneously employing an analog error signal to control one drive output and an analog inversion of that error signal, with respect to a voltage that is equal to the voltage excursion limit of a timing ramp signal, to control the other drive output. In a second embodiment of the invention, a controller employs a comparator to compare an analog error signal against a given voltage excursion limit of a timing ramp signal to perform the functions of determining which of two drive outputs is to be enabled to be modulated and of modifying the voltage excursion limits of the timing ramp signal such that the voltage excursion limit compared by the comparator is switched between two different voltage excursion limits.

Abstract: An error signal isolator circuit for conveying an error signal across an electrical isolation boundary such as an external pulse transformer employs a level shifting process whereby a controllable voltage is measured with respect to a reference voltage and, with any gain implemented in the process, is level shifted upward such that the higher potential is referenced to a supply voltage and the lower potential is used dynamically to control the magnitude of voltage conveyed in a pulse amplitude modulation (PAM) process. In the PAM process, an ON pulse is terminated by monitoring when a PAM current has increased to a predetermined and controllable level. An ON pulse is initiated by monitoring when the voltage across a clamp diode has decayed below its normal forward bias level, indicating a commensurate decay in PAM current, following termination of the previous ON pulse.

Abstract: A primary side controller for regulated power converters may be implemented as a monolithic integrated circuit in which fewer pins are required as compared to the prior art 3842 controller. The present controller includes a current limit protection function having an extended time period over which a predetermined current value is reached.

Abstract: A gate charge recovery circuit prevents generation of the voltage spike that would otherwise appear across the sense resistor that is employed to detect the current flowing through the switched terminal of a gate-driven semiconductor device when the device is turned on. The gate charge recovery circuit comprises the combination of a capacitor connected between the reference terminal of the semiconductor device and the positive terminal of a driver and a filter resistor connected between the positive terminal of the driver and the positive terminal of a voltage source.