Abstract: Embodiments are described for reducing common-mode current in electronic devices. In the various embodiments, a resonant converter is employed, for example in a power supply, and the resonant converter is driven by a DC input to generate an AC primary voltage on the primary windings of a power transformer. The DC input may be derived from an AC line voltage or a DC-to-DC converter. The AC primary voltage drives the primary winding of the transformer to generate an AC secondary voltage on at least one secondary winding of the transformer. The AC secondary voltage may then drive a rectifier, which in turn drives a low-pass filter to produce a DC output voltage. Phase-shift modulation is employed which, in conjunction with the resonant converter, applies a sinusoidal waveform to the primary of the transformer resulting in a reduced amount of common-mode current injected onto the secondary.

Abstract: An energy dissipating device configured to connect to a power supply and to dissipate excess energy from a direct current (DC) rail in response to a change in power supply settings or operating characteristics. The energy dissipating device is connected to the DC rail, which conducts current generated by an AC/DC converter to at least one DC/DC converter. When power demand to the DC/DC converter is reduced, the DC/DC converter generates a supplemental current surge on the DC rail. A rail current monitor monitors the current level on the DC rail and generates the DC rail power signal indicative of the supplemental current surge level generated by the at least one DC/DC converter. The supplemental surge current is used to control dissipative elements connected across the DC rail to modulate a current sink path across the DC rail to dissipate the excess energy from the DC rail.

Abstract: A system for dissipating energy in a power supply includes a bidirectional switching power output stage coupled to a primary power supply side and a secondary power supply side, the bi-directional switching power output stage configured to provide a positive voltage and a positive current, the bi-directional switching power output stage also configured to provide a positive voltage and to receive a current. The system for dissipating energy in a power supply also includes a current sinking circuit coupled to the primary power supply side, the current sinking circuit configured to dissipate energy when the secondary power supply side of the switching power supply is receiving current.

Abstract: An energy dissipating device configured to connect to a power supply and to dissipate excess energy from a direct current (DC) rail in response to a change in power supply settings or operating characteristics. The energy dissipating device is connected to the DC rail, which conducts current generated by an AC/DC converter to at least one DC/DC converter. When power demand to the DC/DC converter is reduced, the DC/DC converter generates a supplemental current surge on the DC rail. A rail current monitor monitors the current level on the DC rail and generates the DC rail power signal indicative of the supplemental current surge level generated by the at least one DC/DC converter. The supplemental surge current is used to control dissipative elements connected across the DC rail to modulate a current sink path across the DC rail to dissipate the excess energy from the DC rail.

Abstract: A device for improving transient response of a power supply includes a diode connected in series with an output of the power supply and configured to provide a predetermined voltage drop to an output voltage of the power supply. The device further includes a source follower transistor connected in parallel with the diode and configured to be selectively activated to remove at least a portion of the predetermined voltage drop of the diode from the output voltage of the power supply during a transient period, in which an output current of the device is increasing.

Abstract: Embodiments are described for reducing common-mode current in electronic devices. In the various embodiments, a resonant converter is employed, for example in a power supply, and the resonant converter is driven by a DC input to generate an AC primary voltage on the primary windings of a power transformer. The DC input may be derived from an AC line voltage or a DC-to-DC converter. The AC primary voltage drives the primary winding of the transformer to generate an AC secondary voltage on at least one secondary winding of the transformer. The AC secondary voltage may then drive a rectifier, which in turn drives a low-pass filter to produce a DC output voltage. Phase-shift modulation is employed which, in conjunction with the resonant converter, applies a sinusoidal waveform to the primary of the transformer resulting in a reduced amount of common-mode current injected onto the secondary.

Abstract: A system for dissipating energy in a power supply includes a bidirectional switching power output stage coupled to a primary power supply side and a secondary power supply side, the bi-directional switching power output stage configured to provide a positive voltage and a positive current, the bi-directional switching power output stage also configured to provide a positive voltage and to receive a current. The system for dissipating energy in a power supply also includes a current sinking circuit coupled to the primary power supply side, the current sinking circuit configured to dissipate energy when the secondary power supply side of the switching power supply is receiving current.

Abstract: A system for controlling mode crossover time in a power supply includes a power output element having a constant voltage control loop and a constant current control loop, the constant voltage control loop having a first error amplifier and the constant current control loop having a second error amplifier. An additional error amplifier is operatively coupled to a compensation capacitance associated with the second error amplifier, the additional error amplifier configured to cause the constant current control loop to provide an additional current to flow from the constant current control loop, thus causing the power output element to transition from a constant voltage mode to a constant current mode responsive to a programmed voltage value.

Abstract: A multi-range measuring circuit for measuring a flow of electrical current between a first node and a second node. A measurement resistor is connected to the first node to develop a voltage having a high range output. A summing node connected in series with the measurement resistor acts as an input to an amplifier for developing a second voltage having a low range output having a higher scale factor than the high range output. If the capacity of the amplifier to maintain the low range as a linear function is exceeded, a bypass circuit bypasses excess current flow to the second node.

Abstract: A multi-range measuring circuit for measuring a flow of electrical current between a first node and a second node. A measurement resistor is connected to the first node to develop a voltage having a high range output. A summing node connected in series with the measurement resistor acts as an input to an amplifier for developing a second voltage having a low range output having a higher scale factor than the high range output. If the capacity of the amplifier to maintain the low range as a linear function is exceeded, a bypass circuit bypasses excess current flow to the second node.

Abstract: A voltage control system that provides an output voltage of constant value to a load. The control system includes voltage supply means for providing the output voltage to the load. A feedback circuit supplies a feedback current. A summing circuit algebraically sums the feedback current and a reference current to provide an error signal that changes as the feedback current changes. These changes affect the amplitude of the output voltage delivered to the load. The error signal is processed by a voltage adjustment means including an error amplifier that amplifies the error signal for use in making an adjustment to the output voltage so as to maintain its constant value. A gain increasing means responds to transient changes in output voltage to momentarily increase the error amplifier gain to shorten system recovery time to constant output voltage.

Abstract: A constant voltage power supply includes one or more sense leads connected to a load and in a feedback control loop. The voltage at the load is fed back via the sense leads for comparison to a reference voltage in the loop to generate an error signal that adjusts the voltage output of the power supply to achieve and maintain the voltage delivered to the load constant at a desired value. The power supply further includes a continuity checking circuit for checking continuity status of the sense leads while the power supply is in a disable mode wherein it is isolated from the load. This allows any detected discontinuity to be repaired before the supply is connected to a load. The detected discontinuity informs the user that the voltage delivered to the load will not be accurately controlled because of the broken or disconnected sense lead.