Abstract: Disclosed herein is a symmetric split planar transformer in the context of a DC-DC isolated converter. The symmetric split planar transformer reduces or eliminates asymmetry in the distribution of parasitic capacitance across the isolation barrier going from one end to another end of a primary coil, and as a result, undesirable electromagnetic interference (EMI) due to common mode dipole emission across the isolation barrier may be reduced. In some embodiments, the primary winding is split into at least a first coil and a second coil, each occupying a different area side-by-side on a substrate. The transformer is symmetric in the sense that a capacitive coupling of the first coil to a secondary winding is the same as a capacitive coupling of the second coil to the secondary winding, such that common mode EMI may be reduced. Each coil may include stacked spiral coil portions in multiple metal planes to increase inductive density across the isolation barrier.

Abstract: Disclosed herein is a symmetric split planar transformer in the context of a DC-DC isolated converter. The symmetric split planar transformer reduces or eliminates asymmetry in the distribution of parasitic capacitance across the isolation barrier going from one end to another end of a primary coil, and as a result, undesirable electromagnetic interference (EMI) due to common mode dipole emission across the isolation barrier may be reduced. In some embodiments, the primary winding is split into at least a first coil and a second coil, each occupying a different area side-by-side on a substrate. The transformer is symmetric in the sense that a capacitive coupling of the first coil to a secondary winding is the same as a capacitive coupling of the second coil to the secondary winding, such that common mode EMI may be reduced. Each coil may include stacked spiral coil portions in multiple metal planes to increase inductive density across the isolation barrier.

Abstract: Disclosed herein is a symmetric transformer in the context of a DC-DC isolated converter. The symmetric transformer reduces or eliminates asymmetry in the distribution of parasitic capacitance across the isolation barrier going from one end to another end of a primary coil, and as a result, undesirable electromagnetic interference (EMI) due to common mode dipole emission across the isolation barrier may be reduced. In some embodiments, a primary winding is split into separate first and second coils, with a serial impedance connected in between the first and second coils. The transformer is symmetric in the sense that a capacitive coupling of the first coil to a secondary winding is the same as a capacitive coupling of the second coil to the secondary winding, such that common mode EMI may be reduced.

Abstract: In described examples, an isolated DC-DC converter includes: an input node for receiving an input voltage; a transformer including a primary side having first and second terminals and a primary side ground; and first and second low-side switches. The first low-side switch is coupled between the first terminal and the primary side ground. The second low-side switch is coupled between the second terminal and the primary side ground. A first voltage is across the first low-side switch, and a second voltage is across the second low-side switch. Also, the isolated DC-DC converter includes first and second high-side switches. The first high-side switch is coupled between the first terminal and the input node. The second high-side switch is coupled between the second terminal and the input node. Further, the isolated DC-DC converter includes a switch controller.

Abstract: Methods and systems for providing electrical power using an isolated DC-DC converter include: using a power supply to provide multiple amplitudes of open loop current to a primary side of a transformer. The amplitudes are selected to increase stepwise, at predetermined times, to ramp a voltage across output terminals connected to a secondary side of said transformer so that after said power supply provides a maximum open loop current amplitude, said voltage reaches a threshold sufficient to enable a closed loop controller connected to said output terminals to send a feedback signal to said primary side. The threshold voltage is insufficient to fully power said output terminals. The feedback signal is selected to control said power supply to increase current to said primary side at closed loop current levels until said output terminals are fully powered.

Abstract: A converter circuit includes a primary side having a resonator and a first control circuit configured to control the resonator. The converter circuit also includes a secondary side having a resonant rectifier and a second control circuit configured to control the resonant rectifier. The converter circuit further includes a transformer configured to electrically isolate the primary side from the secondary side. The second control circuit is configured to turn the resonant rectifier on and off. The first control circuit may be configured to detect when the resonant rectifier is off and, in response, turn the resonator off without using a feedback signal from the secondary side. The first control circuit may be configured to detect when the resonant rectifier is off by detecting when input power to the primary side decreases. The resonant rectifier could be turned on and off by detuning the resonant rectifier.

Abstract: Disclosed examples include isolated load switch driver circuits to drive a load, including an impedance circuit that receives a digital input voltage signal from a signal source, and selectively allows a current signal to flow from the signal source to charge a buffer capacitor. An impedance control circuit controls the impedance circuit to limit the current signal in response to the buffer capacitor reaching a first threshold voltage, and an output circuit provides an output isolated from the digital input voltage signal to switch the load. A signaling circuit selectively enables the output circuit to draw power from the buffer capacitor in response to the voltage of the buffer capacitor reaching the first threshold voltage.

Abstract: In described examples, an isolated DC-DC converter includes: an input node for receiving an input voltage; a transformer including a primary side having first and second terminals and a primary side ground; and first and second low-side switches. The first low-side switch is coupled between the first terminal and the primary side ground. The second low-side switch is coupled between the second terminal and the primary side ground. A first voltage is across the first low-side switch, and a second voltage is across the second low-side switch. Also, the isolated DC-DC converter includes first and second high-side switches. The first high-side switch is coupled between the first terminal and the input node. The second high-side switch is coupled between the second terminal and the input node. Further, the isolated DC-DC converter includes a switch controller.

Abstract: Disclosed examples include isolated dual active bridge (DAB) DC to DC converters with first and second bridge circuits, a transformer with a sense coil, and a secondary side control circuit to provide secondary side switching control signals to regulate an output voltage or current signal by controlling a phase shift angle between switching transitions of the secondary side switching control signals and switching transitions of a secondary side clock signal, where the secondary side control circuit includes a clock recovery circuit to synchronize the secondary side clock signal to transitions in a sense coil voltage signal of the sense coil.

Abstract: In described examples, an isolated DC-DC converter includes an input node for receiving an input voltage, and a transformer including a primary side having first and second terminals and a ground. First and second high-side switches are coupled between the input node and the first and second terminals, respectively. A first low-side switch is coupled between the first terminal and the ground, and through a first voltage limiter to be activated by a voltage at the second terminal. A second low-side switch is coupled between the second terminal and the ground, and through a second voltage limiter to be activated by a voltage at the first terminal. A switch controller controls the high-side switches so that voltages across the high-side switches are alternatingly zero, using a current through the primary side to alternatingly charge one terminal to an input voltage and discharge the other terminal to a ground voltage.

Abstract: In described examples, an isolated DC-DC converter includes: an input node for receiving an input voltage; a transformer including first and second terminals; first and second low-side switches; and first and second high-side switches. The first low-side switch is coupled between the first terminal and a primary side ground. The second low-side switch is coupled between the second terminal and the primary side ground. The first high-side switch is coupled between the first terminal and the input node and is configured to be activated by a voltage at the second terminal. The second high-side switch is coupled between the second terminal and the input node and is configured to be activated by a voltage at the first terminal. Further, the isolated DC-DC converter includes a switch controller to cause the first and second voltages to alternatingly be zero by opening and closing the first and second low-side switches.

Abstract: Disclosed examples include isolated load switch driver circuits to drive a load, including an impedance circuit that receives a digital input voltage signal from a signal source, and selectively allows a current signal to flow from the signal source to charge a buffer capacitor. An impedance control circuit controls the impedance circuit to limit the current signal in response to the buffer capacitor reaching a first threshold voltage, and an output circuit provides an output isolated from the digital input voltage signal to switch the load. A signaling circuit selectively enables the output circuit to draw power from the buffer capacitor in response to the voltage of the buffer capacitor reaching the first threshold voltage.

Abstract: Disclosed examples include isolated load switch driver circuits to drive a load, including an impedance circuit that receives a digital input voltage signal from a signal source, and selectively allows a current signal to flow from the signal source to charge a buffer capacitor. An impedance control circuit controls the impedance circuit to limit the current signal in response to the buffer capacitor reaching a first threshold voltage, and an output circuit provides an output isolated from the digital input voltage signal to switch the load. A signaling circuit selectively enables the output circuit to draw power from the buffer capacitor in response to the voltage of the buffer capacitor reaching the first threshold voltage.

Abstract: Disclosed examples include isolated dual active bridge (DAB) DC to DC converters with first and second bridge circuits, a transformer with a sense coil, and a secondary side control circuit to provide secondary side switching control signals to regulate an output voltage or current signal by controlling a phase shift angle between switching transitions of the secondary side switching control signals and switching transitions of a secondary side clock signal, where the secondary side control circuit includes a clock recovery circuit to synchronize the secondary side clock signal to transitions in a sense coil voltage signal of the sense coil.

Abstract: Disclosed examples include isolated dual active bridge (DAB) DC to DC converters with first and second bridge circuits, a transformer with a sense coil, and a secondary side control circuit to provide secondary side switching control signals to regulate an output voltage or current signal by controlling a phase shift angle between switching transitions of the secondary side switching control signals and switching transitions of a secondary side clock signal, where the secondary side control circuit includes a clock recovery circuit to synchronize the secondary side clock signal to transitions in a sense coil voltage signal of the sense coil.

Abstract: Described examples include DC to DC converters and systems with switching circuitry formed by four series-connected switches, inductors connected between the ends of the switching circuitry and corresponding output nodes, and with a flying capacitor coupled across interior switches of the switching circuitry and a second capacitor coupled across the ends of the switching circuitry. A control circuit operates the switching circuit to control a voltage signal across the output nodes using a first clock signal and a phase shifted second clock signal to reduce output ripple current and enhance converter efficiency using valley current control. The output inductors are wound on a common core in certain examples.

Abstract: Disclosed examples include isolated dual active bridge (DAB) DC to DC converters with first and second bridge circuits, a transformer with a sense coil, and a secondary side control circuit to provide secondary side switching control signals to regulate an output voltage or current signal by controlling a phase shift angle between switching transitions of the secondary side switching control signals and switching transitions of a secondary side clock signal, where the secondary side control circuit includes a clock recovery circuit to synchronize the secondary side clock signal to transitions in a sense coil voltage signal of the sense coil.

Abstract: Disclosed examples include isolated dual active bridge (DAB) DC to DC converters with first and second bridge circuits, a transformer with a sense coil, and a secondary side control circuit to provide secondary side switching control signals to regulate an output voltage or current signal by controlling a phase shift angle between switching transitions of the secondary side switching control signals and switching transitions of a secondary side clock signal, where the secondary side control circuit includes a clock recovery circuit to synchronize the secondary side clock signal to transitions in a sense coil voltage signal of the sense coil.

Abstract: An isolated DC-DC converter 400 includes a plurality of modules, an output node, and a transformer with a secondary side having first and second terminals and a secondary side ground. Ones of the modules includes a first low-side switch coupled between the first terminal and a low-voltage node, and a second low-side switch is coupled between the second terminal and the low-voltage node. A first high-side switch is coupled between the first terminal and a high-voltage node, and is activated by a voltage at the second terminal. A second high-side switch is coupled between the second terminal and the high-voltage node, and is activated by a voltage at the first terminal. The isolated DC-DC converter also includes a switch controller to open and close the first and second low-side switches at times corresponding to a frequency of the converter.

Abstract: In described examples, an isolated DC-DC converter includes an input node for receiving an input voltage, and a transformer including a primary side having first and second terminals and a ground. First and second high-side switches are coupled between the input node and the first and second terminals, respectively. A first low-side switch is coupled between the first terminal and the ground, and through a first voltage limiter to be activated by a voltage at the second terminal. A second low-side switch is coupled between the second terminal and the ground, and through a second voltage limiter to be activated by a voltage at the first terminal A switch controller controls the high-side switches so that voltages across the high-side switches are alternatingly zero, using a current through the primary side to alternatingly charge one terminal to an input voltage and discharge the other terminal to a ground voltage.