US Pat. No. 10,091,844

POWER SUPPLY FOR LED LAMP WITH TRIAC DIMMER

BCD Semiconductor Manufac...

1. A control circuit for an LED (light-emitting diode) lighting system that includes a rectifier circuit for coupling to an AC input voltage through a TRIAC (Triode for Alternating Current) dimmer, the TRIAC dimmer being characterized by a holding current, the rectifier circuit being configured to provide a rectified DC input voltage to an inductor for supplying a constant current to an LED load, the control circuit comprises:a controller for coupling to a power switch for controlling a current flow in the inductor, the controller being configured to control current pulses in the inductor such that an envelope waveform formed by peak points of the current pulses is in phase with the AC input voltage; and
a bleeder circuit coupled to the rectifier circuit, wherein the bleeder circuit is configured to determine if that a current flow through the rectifier circuit is below the holding current of the TRIAC; and
wherein the bleeder circuit is configured to provide a compensation current, upon determining that the current flow through the rectifier circuit is below the holding current of the TRIAC, to maintain a current flow through the rectifier circuit at a magnitude of at least the holding current of the TRIAC;
wherein the bleeder circuit comprises:
a first resistor and a bipolar transistor coupled in series between the first output terminal of the rectifier circuit and a ground, a base of the bipolar transistor being coupled to a bias voltage;
a second resistor coupled between the second output terminal of the rectifier circuit and the ground; and
first and second diodes coupled in series between the second output terminal of the rectifier circuit and the base of the bipolar transistor.

US Pat. No. 9,318,962

CIRCUITS AND METHODS FOR REDUCING OUTPUT VOLTAGE OVERSHOOT OF SWITCH MODE POWER SUPPLY

BCD Semiconductor Manufac...

1. A switching mode power supply (SMPS), comprising:
a transformer having:
a primary winding for coupling to an input power source;
a secondary winding for providing an output voltage of the SMPS; and
an auxiliary winding;
a power transistor coupled to the primary winding;
a primary side control circuit coupled to the auxiliary winding and the power transistor, the primary side control circuit
being configured to regulate the output of the SMPS by controlling the power switch in response to a feedback voltage signal
that is representative of an output of the SMPS; and

a secondary-side control circuit coupled to the secondary winding and being configured to cause the output voltage of the
SMPS to discharge when the output voltage of the SMPS is higher than a first overvoltage reference voltage;

wherein the secondary-side control circuit comprises a discharge control circuit having a power supply terminal coupled to
the output voltage of the SMPS, the discharge control circuit being configured to issue a discharge signal;

wherein the discharge control circuit comprises a comparator having a negative input coupled to the second reference voltage
and a positive input coupled to a third reference voltage that is lower than the second reference voltage, the comparator
also having a power supply terminal coupled to the output voltage of the SMPS.

US Pat. No. 9,134,349

AMPLIFIER CIRCUITS AND METHODS

BCD Semiconductor Manufac...

1. A chopper amplifier circuit for sensing Hall voltage, the amplifier circuit comprising:
a Hall sampling circuit, including a first switching circuit for selectively coupling each of four nodes of a Hall plate to
either a power source or a ground terminal;

a differential amplifier;
a second switching circuit configured for selectively coupling each of the four nodes of the plate to inputs of the differential
amplifier;

a Hall voltage signal retaining circuit, including a first group of four storage devices and a second group of four storage
devices;

a third switching circuit configured for storing a first output of the differential amplifier to one of the first group of
four storage devices and for storing a second output of the differential amplifier to one of the second group of four storage
devices; and

a fourth switching circuit configured for selectively coupling the first group of four storage devices to a first output of
the chopper amplifier circuit and for coupling the second group of four storage devices to a second output of the chopper
amplifier circuit.

US Pat. No. 9,520,868

POWER TRANSISTOR DRIVING CIRCUITS AND METHODS FOR SWITCHING MODE POWER SUPPLIES

BCD Semiconductor Manufac...

1. A driver circuit, the driver circuit comprising:
a current mirror having first and second PMOS transistors;
a bipolar transistor coupled to the second PMOS transistor of the current mirror to receive a first current; and
a plurality of serially connected diode devices coupled between a collector and a base of the bipolar transistor;
wherein the collector of the bipolar transistor is configured to provide a driving voltage according to the number of the
plurality of serially-connected diode devices and the size ratio between the first and the second PMOS transistors.

US Pat. No. 9,853,542

CONSTANT-VOLTAGE AND CONSTANT-CURRENT BUCK CONVERTER AND CONTROL CIRCUIT

BCD SEMICONDUCTOR MANUFAC...

1. A control circuit for a buck converter, the buck converter including at least an inductor coupled to an output of the buck
converter, the control circuit comprises: a power switch configured for coupling to a line voltage and configured for charging
the inductor; an input line voltage sampling circuit configured to provide a sampled input line voltage; and a constant-voltage
(CV) and constant-current (CC) control module coupled to the power switch, wherein the CV and CC control module is configured
to: during a charging period of the inductor, enable the input line voltage sampling circuit to provide the sampled input
line voltage; modify a threshold voltage for controlling a peak inductor current based on the sampled input line voltage;
and control the power switch to provide a constant output current by maintaining a constant peak inductor current in response
to the sampled input line voltage; and during a discharging period of the inductor, to monitor the sensed output voltage to
control the power switch to provide a constant output voltage.

US Pat. No. 10,462,868

CIRCUIT AND METHOD FOR DRIVING LED LAMP WITH A DIMMER

BCD Semiconductor Manufac...

1. A driver circuit for an LED (light-emitting diode) lamp, comprising:a transformer having a primary winding and a secondary winding;
a dimmer circuit coupled to a power source and the primary winding for varying an input voltage to the primary winding;
a power switch coupled to the primary winding for controlling a current flow in the primary winding;
an output rectifying circuit coupled to the secondary winding and the LED lamp for providing an output current to the LED lamp;
a controller coupled to the dimmer circuit to receive an average input voltage signal from the dimmer circuit, the controller being coupled to a control terminal of the power switch and configured to vary the output current according to the average input voltage signal.