Hong Kong Applied Science and Technology Research Institute Company, Limited

Tak Lok Shum

Ziyang Gao

Xiaoyong Hu

Shek Mong Wong

Yuxie Cheng

Chi Man Cheng

A start-up routine for a Switched-Mode Power Supply (SMPS) gradually increases the duty cycle while reducing an initial dead time to a final optimal dead time for normal operation. Reliability is improved by the larger initial dead time that reduces ringing in switching transistors during low-voltage conditions early in the start-up sequence. Efficiency is improved by reducing the optimal dead time as voltages approach operating levels. The initial dead time is pre-calculated as a function of the input voltage and initial duty cycle. Optimal dead times are pre-calculated as a function of output voltage and output current. The optimal dead time is adjusted for each iteration of a second loop that also increases duty cycle until the target operating output voltage is reached. Pre-calculated dead times are based on the time required to fully charge and discharge parasitic drain-to-source capacitances in the switching transistors in the SMPS circuit.

Adaptive dead-time control of a synchronous buck converter

A DC-DC power converter has an auxiliary tank cascaded to share an efficiency tank's inductor, capacitor, and transformer. Switching transistors pump the auxiliary tank at startup to provide a boost current. The switching frequency is reduced in steps and the voltage gain and power of the converter sensed until the voltage gain matches a voltage gain calculated for the efficiency tank. Then tank switchover occurs and transistors to the efficiency tank are pumped with the last switching frequency used by the auxiliary tank, and the auxiliary tank is not pumped. Since the voltage gains before and after tank switchover are equal, no output voltage deviation or current spike occurs. A voltage sag or failure switches back to the auxiliary tank at a switching frequency determined by a dynamic contour line where the voltage gains of the two tanks are equal for the current power state.

Seamless switching of resonant tanks in power converters by matching voltage gains at tank switchover

A power device package includes a substrate, a high side power device, a low side power device and a driver device. The substrate includes a top surface, a bottom surface and a plurality of vias that extend through the substrate. The high side and low side power devices are disposed on the top surface of the substrate and connected with each other. The driver device is disposed on the bottom surface of the substrate and electrically connected with the high side and low side power devices through the vias to drive the high side and low side power devices in response to a control signal. The distance between the driver device and the high side and low side power devices is determined by the thickness of the substrate such that that a parasitic inductance between the driver device and the high side power device or the low side power device is reduced.

Power device package

Two or more power converters are connected in parallel to supply power current to a joining node through connecting resistors. An output voltage before the connecting resistor in each power converter is sampled and divided by a sampling ratio to generate sampled voltages for each power converter. A current sharing circuit for each power converter receives the local sampled voltage and another sampled voltage from another power converter. The current sharing circuit generates an adjustment voltage that is injected into a feedback loop. The adjustment voltage modifies the output voltage of the power converter, adjusting and balancing the power current delivered by that power converter. Power currents from several power converters are reduced and balanced when the same sampling ratio is used for all power converters. Current hogging by one power converter is prevented.

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Hong Kong, China

Tak Lok Shum