Rohm Co., Ltd.

Hiroki Kikuchi

Ryo Shimizu

Taichi Hoshino

Junichi Hagino

Daisuke Uchimoto

Masao Yonemaru

Naoki Inoue

Hiroyuki Hatano

Takashi Oki

Min-Ki Ahn

Takumi Oe

Hiroyuki Murakami

Jung-nam In

The present disclosure provides a power supply control device and a flyback converter. The power supply control device includes: a comparator, comparing a current sensing signal generated by IN conversion of a primary side current flowing in the primary winding with a threshold voltage; a switching controller, turning off a switching element according to a comparing result of the current sensing signal and the threshold voltage by the comparator; an external terminal, connectable to a connection node of an external resistor connected in series between one end of the auxiliary winding and an application end of a ground potential; a current detector, detecting a terminal current flowing through the external terminal; and a threshold voltage corrector, correcting the threshold voltage based on a current detection signal of the current detector.

Power supply control device and flyback converter

A synchronous rectification controller that controls driving a synchronous rectification transistor arranged on secondary side, includes: a gate terminal being electrically connectable to a gate of the synchronous rectification transistor; a drain terminal being electrically connectable to a drain of the synchronous rectification transistor via a first resistor; a first comparator comparing a drain terminal voltage generated at the drain terminal with negative first threshold voltage; a second comparator comparing the drain terminal voltage with negative second threshold voltage higher than the first threshold voltage; and a driver performing on/off control of the synchronous rectification transistor based on result of the comparison by the first comparator and result of the comparison by the second comparator, wherein when the synchronous rectification transistor is turned on, voltage is added to the drain terminal voltage by current flowing through the first resistor according to a second resistor.

Synchronous rectification controller and isolated synchronous rectification type dc/dc converter

A power control device for controlling driving of an LLC resonant converter including a first switching element to one end of which an input voltage is applied, a second switching element of which one end is connected to the other end of the first switching element, and a primary winding and a resonant capacitor connected in series between a first connection node at which the first and second switching elements are connected together and the other end of the second switching element includes an on-timing controller that detects variation of a switching voltage detection signal based on a switching voltage appearing at the first connection node rising up to the input voltage and falling down to 0 V and that, based on the result of the detection, generates a high-side on-signal for turning on the first switching element and a low-side on-signal for turning on the second switching element.

Power supply control device and LLC resonant converter

An isolated synchronous rectifying DC/DC converter includes a drain terminal connected to a drain of a synchronous rectification transistor, a source terminal connected to a source of the synchronous rectification transistor; a comparator configured to compare a drain voltage of the drain terminal with a predetermined threshold voltage which set is based on a potential of the source terminal, a first flip-flop to which an OFF signal output from the comparator is input, a driver configured to output a gate signal to the synchronous rectification transistor based on an output signal of the first flip-flop, and a first abnormality detection circuit including an abnormality detection comparator configured to compare a voltage of the source terminal with a detection threshold voltage, and configured to output a first abnormality detection signal based on an output of the abnormality detection comparator.

Isolated synchronous rectifying DC/DC converter

A synchronous rectification controller includes: a drain terminal connected to a drain of a synchronous rectification transistor; a first comparator configured to compare a drain voltage of the drain terminal with a first threshold voltage; a second comparator configured to compare the drain voltage of the drain terminal with a second threshold voltage; a flip-flop to which an ON signal output from the first comparator and an OFF signal output from the second comparator are input; a driver configured to output a gate signal to the synchronous rectification transistor based on an output signal of the flip-flop; and a threshold adjusting part configured to adjust the second threshold voltage based on the drain voltage.

An isolated synchronous rectification type DC/DC converter, includes: a transformer including primary and secondary windings; a switching transistor connected to the primary winding; a synchronous rectifying transistor installed between the secondary winding and a ground line on the secondary side; a photocoupler including a light emitting device and a light receiving device; a feedback circuit driving the light emitting device such that an output voltage of the DC/DC converter approaches a target voltage; a primary side controller connected to the light receiving device and switching the switching transistor depending on feedback signal from the photocoupler; a synchronous rectification controller controlling the rectifying transistor; and a protection circuit including a temperature detection element, one end of the detection element connected to a drain of the rectifying transistor, the protection circuit configured to detect an overheated state of the rectifying transistor depending on a first signal generated by the temperature detection element.

Insulated synchronous rectification type DC/DC converter, and power adaptor and electronic device

A secondary controller drives a light emitting element of a photocoupler such that a detection voltage Vcorresponding to an output voltage Vgenerated in an output capacitor C approximates to a reference voltage V. A primary controller controls a switching transistor M according to a feedback signal V. A protection circuit is activated and drives the light emitting element of the photocoupler when detecting an abnormal state. An auxiliary power supply circuit includes a power supply capacitor C provided separately from the output capacitor C and supplies a power supply voltage Vto the protection circuit and an anode of the light emitting element of the photocoupler.

Isolated synchronous rectification-type DC/DC converter

A secondary-side module comprises: a synchronous rectification controller that controls a synchronous rectification transistor; and a shunt regulator that generates a current that corresponds to the difference between an output voltage Vof a DC/DC converter and the target value of the output voltage, which are housed in a single package. The multiple pins to be connected to the shunt regulator are all laid out along a first side of the package.

Insulated synchronous rectification DC/DC converter

A rectifier IC seals, in a single package, a first transistor chip which integrates a first transistor, a second transistor chip which integrates a second transistor and a controller chip which detects a first node voltage and a second node voltage of each of the transistors so as to perform on/off control on the transistors, and the rectifier IC functions as a secondary-side rectification means of an isolated switching power supply.

Rectifier IC and isolated switching power supply using same

A synchronous rectification controller includes a first gate pin coupled to a gate of a first synchronous rectification transistor, a first drain pin coupled to a drain of the first synchronous rectification transistor, a second gate pin coupled to a gate of a second synchronous rectification transistor, a second drain pin coupled to a drain of the second synchronous rectification transistor, a source pin coupled to a ground, a multiplexer selecting a voltage applied to the first drain pin in a first state, and selecting a voltage applied to the second drain pin in a second state, a pulse generator generating a pulse signal based on an output voltage of the multiplexer, a driving circuit switching the first synchronous rectification transistor according to the pulse signal in the first state, and switching the second synchronous rectification transistor according to the pulse signal in the second state.

Synchronous rectification controller including synchronous rectification transistor for insulated synchronous rectification DC/DC converter

A synchronous rectification controller configured to control a synchronous rectification transistor is provided on the secondary side of an insulated synchronous rectification DC/DC converter. A DRAIN pin receives the drain voltage Vof the synchronous rectification transistor. A pulse generator generates a pulse signal Sbased on the voltage at the DRAIN pin. A driver drives the synchronous rectification transistor based on the pulse signal S. Upon detecting an open-circuit fault of the DRAIN pin, an abnormality detection circuit asserts an abnormality detection signal S.

Insulated synchronous rectification DC/DC converter including synchronous rectification controller controlling synchronous rectification transistor

An isolated DC/DC converter includes a transformer having a first winding and a secondary winding, a switching transistor connected to the primary winding of the transformer, a rectifier element connected to the secondary winding of the transformer, a photocoupler, a feedback circuit configured to drive a light emitting element on an input side of the photocoupler by a forward current corresponding to an error between an output voltage of the DC/DC converter and a target voltage of the DC/DC converter, a conversion circuit configured to convert a collector current flowing in a light receiving element on an output side of the photocoupler into a feedback voltage having a negative correlation with the collector current, a pulse signal generator configured to generate a pulse signal corresponding to the feedback voltage, and a driver configured to drive the switching transistor depending on the pulse signal.

Isolated DC/DC converter, primary side controller, power adapter, and electronic device

When a pulse generator detects that a switching transistor on a primary side of a DC/DC converter turns off, the pulse generator sets a pulse signal Sto an on level configured as an instruction to turn on a synchronous rectification transistor. When the pulse generator detects that the current that flows through the secondary winding of a transformer becomes substantially zero, the pulse generator sets the pulse signal Sto an off level configured as an instruction to turn off the synchronous rectification transistor. After a predetermined time-up period elapses after the detection of the turn-on of the switching transistor, a forced turn-off circuit forcibly turns off the synchronous rectification transistor.

An insulated DC/DC converter includes: a transformer; a switching transistor; a rectifier circuit; a photocoupler; a feedback circuit configured to drive a light emitting element of the photocoupler such that an output voltage of the DC/DC converter approaches a target voltage; a primary side controller having a feedback terminal which is connected to a light receiving element of the photocoupler and receives a feedback signal from the photocoupler, a zero current detection terminal which receives a zero current detection signal corresponding to a voltage generated at one end of an auxiliary winding of the transformer, and a pulse modulator of a quasi-resonant mode configured to generate a pulse signal depending on the feedback signal and the zero current detection signal; and a starting control circuit which, in start-up of the DC/DC converter, electrically affects the zero current detection terminal such that an OFF time of the switching transistor lengthens.

Insulated DC/DC converter, and power adaptor and electronic device using the same

A synchronous rectifying controller on secondary side of insulating synchronous rectifying converter to control synchronous rectifying transistor, comprising: first comparator to compare drain voltage of the transistor with first negative threshold voltage, and assert set signal based on the comparison of them; second comparator to compare drain voltage with second negative threshold voltage, and assert reset signal based on the comparison of them; third comparator to compare drain voltage with third positive threshold voltage, and assert release signal based on the comparison of them; control circuit set in response to the assertion of the set signal and to adjust control pulse to have ON level, and reset in response to the assertion of the reset signal and to adjust the control pulse to have OFF level; and driver to drive the transistor, wherein set operation of the control circuit is inhibited until the release signal is asserted.

Insulating synchronous rectifying DC/DC converter, synchronous rectifying controller, power supply using the same, power adapter and electronic device, and control method of synchronous rectifying controller

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Kyoto, Japan

Hiroki Kikuchi