Stmicroelectronics S.r.l.

Stmicroelectronics Design and Application S.r.o.

Alberto Iorio

Maurizio Foresta

Emilio Volpi

Jeanpierre Vicquery

Alberto Bianco

Claudio Adragna

Giuseppe Scappatura

Silvio De Simone

Jan Novotny

A synchronous rectifier driver circuit is configured to drive a synchronous rectifier FET and includes a first terminal configured to be connected to a source terminal of the synchronous rectifier FET. A second terminal is configured to be connected to a drain terminal of the synchronous rectifier FET, and a third terminal is configured to be connected to a gate terminal of the synchronous rectifier FET. The synchronous rectifier driver circuit is configured to measure the voltage between the second terminal and the first terminal, and detect a switch-on instant in which the measured voltage reaches a first threshold value and a switch-off instant in which the measured voltage reaches a second threshold value. The synchronous rectifier driver circuit generates a drive signal between the third terminal and the first terminal as a function of the measured voltage.

Synchronous rectifier driver circuit, related integrated circuit, electronic resonant converter and method

A method of controlling synchronous rectification transistors in a switching converter includes sensing a drain-to-source voltage across each synchronous rectification transistor each switching half-cycle of the switching converter. An average of the sensed drain-to-source voltage is calculated for each synchronous rectification transistor over N prior switching half-cycles. A load current transient in the switching converter is sensed based on the sensed drain-to-source voltage of each synchronous rectification transistor and the calculated average of the sensed drain-to-source voltage for each synchronous rectification transistor over the N prior switching half-cycles.

Control method and system for prevention of current inversion in rectifiers of switching converters

Various embodiments provide a resonant converter that includes a synchronous rectifier driver. The synchronous rectifier driver reduces voltage spikes on drains of transistors within the resonant converter by placing an active clamp between the drains of the transistors and an output terminal of the resonant converter. The active clamp reduces the voltage spikes by sinking current at the drains of the transistors to an output capacitor. By sinking the current to the output terminal, power loss is minimized and efficiency of the resonant converter is improved.

Synchronous rectifier gate driver with active clamp

A voltage comparator for detecting a voltage difference in a high-voltage domain, wherein said comparator receives an input voltage and compares it with a reference voltage also received in input, in which the output voltage from the comparator assumes the logic value 1 if the input voltage is greater than the reference voltage and assumes the logic value 0 if the input voltage is less than or equal to the reference voltage, wherein said comparator comprises low-voltage components and a single high-voltage component. In particular, the low-voltage components are MOS transistors and the high-voltage component is a high-voltage PMOS.

High voltage comparator with low-sensitivity to variations of process/temperature and supply

A driver includes a high-side driver transistor coupled between supply voltage and the gate drive nodes and provides a first charge current to a high side gate node of the high-side driver transistor until the gate drive node reaches a first gate drive threshold. Then a second charge current is provided to the high side gate node that is less than the first charge current. The gate drive node is limited to a first clamped threshold for a delay time. A gate drive current rise signal sets the value of the second charge current that charges the high side gate node and after the delay time the gate drive voltage is limited to a second clamped threshold greater than the first clamped threshold but less than the supply voltage. A gate drive programmable control signal sets the value of the second clamped threshold.

Driver for a power field-effect transistor with a programmable drive voltage, and related systems and methods

A driver circuit for synchronous rectifier electronic switches, such as SR MOSFETs in resonant converters controls a pair of synchronous rectifier electronic switches to apply thereto a drive voltage to switch the synchronous rectifier electronic switches on and off synchronously with a converter current. The driver circuit includes a programming module to produce a first signal indicative of the figure of merit of the synchronous rectifier electronic switches, and, optionally, a current sensing module to produce a second signal indicative of the output current of the synchronous rectifier electronic switches. An output module is included to generate a value for the drive voltage which is a function of the first signal indicative of the figure of merit and, optionally, of the second signal indicative of the output current of the synchronous rectifier electronic switches.

Driver circuit for synchronous rectifier switches in resonant converters, corresponding converter and method

A control device controls a rectifier of a switching converter that is supplied with an input voltage and provides an output current. The rectifier is configured to rectify the output current of the converter and has at least one transistor. The control device, when the at least one transistor is turned off, provides a slow discharge path to ground in a normal operation condition and provides a fast discharge path to ground for discharging the control terminal of the at least one transistor in response to detecting a zero cross event of the current flowing through said at least one transistor.

Control device for rectifiers of switching converters

A control device for a transistor of a switching converter rectifier generates a control signal of the transistor and includes a circuit to measure the conduction time of the body diode of the transistor cycle by cycle. When the conduction time is greater than a first threshold, the off time instant of the transistor is delayed by a first quantity in the next cycles, until the conduction time is less than the first threshold and greater than a second threshold. When the conduction time is between the first and second thresholds, the off time instant is delayed by a fixed second quantity in the next cycles until the conduction time is lower than the second threshold, with the second quantity less than the first quantity. When the conduction time is lower than the second threshold, the off time instant is advanced by the second quantity in the next cycle.

Control method for rectifier of switching converters

A control device detects zero crossings of a current through a rectifier transistor during plural cycles; generates a turn-on signal of the transistor and inserts a turn-on delay equal to a fixed first quantity from the start time of for each cycle. The control device starts counting consecutive cycles after inserting the turn-on delay; detects whether a zero crossing of the current through the transistor after turning on said transistor has occurred; if no zero crossing is detected before counting a number N of consecutive cycles, decreases the turn-on delay by a fixed second quantity for the next cycle; if a zero crossing is detected, maintains turned on the transistor; if the turn-on delay is smaller than first quantity, increases the turn-on delay o for the next switching cycle; and if the turn-on delay is equal to the first quantity, maintains the turn-on delay for the next switching cycle.

A control device for a rectifier of a switching converter that includes a rectifier with at least one MOS transistor and a control device that is configured to generate a turn on and off signal for the at least one transistor. The control device also includes a measuring circuit to measure the conduction time of the body diode of the at least one transistor during each converter switching half-cycle. The control device is configured to, cycle by cycle: verify if the drain-source voltage of the at least one transistor is greater or less than a voltage threshold, and if the drain-source voltage is greater than the voltage threshold to turn off the at least one transistor, measure the conduction time of the body diode and increase the voltage threshold by a quantity in the next switching cycle.

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Aosta, Italy

Alberto Iorio