| Patent application number | Description | Published |
|---|
| 20080259650 | Changing switching frequency of a primary side power converter to compensate for inductance variation - A comparing circuit and a control loop are used to maintain the peak level of current flowing through an inductor of a flyback converter. An inductor switch control signal controls a switch through which the inductor current flows. The inductor current increases at a ramp-up rate during a ramp time and stops increasing at the end of the ramp time. The comparing circuit generates a timing signal that indicates a target time at which the inductor current would reach a predetermined current limit if the inductor current continued to increase at the ramp-up rate. The control loop then receives the timing signal and compares the target time to the end of the ramp time. The pulse width of the inductor switch control signal is increased when the target time occurs after the end of the ramp time. Adjusting the frequency and pulse width controls the peak of the inductor current. | 10-23-2008 |
| 20080259651 | Constant current and voltage controller in a four-pin package with dual-use pin - A comparing circuit and a control loop are used to maintain the peak level of current flowing through an inductor of a flyback converter. An inductor switch control signal controls an inductor switch through which the inductor current flows. The inductor current increases at a ramp-up rate during a ramp time and stops increasing at the end of the ramp time. The comparing circuit generates a timing signal that indicates a target time at which the inductor current would reach a predetermined current limit if the inductor current continued to increase at the ramp-up rate. The control loop then receives the timing signal and compares the target time to the end of the ramp time. The pulse width of the inductor switch control signal is increased when the target time occurs after the end of the ramp time. Adjusting the pulse width controls the peak of the inductor current. | 10-23-2008 |
| 20080259652 | Compensating for base current in a primary side power converter that uses an NPN bipolar transistor - A comparing circuit and a control loop are used to maintain the peak level of current flowing through an inductor of a flyback converter. An inductor switch control signal controls a switch through which the inductor current flows. The inductor current increases at a ramp-up rate during a ramp time and stops increasing at the end of the ramp time. The comparing circuit generates a timing signal that indicates a target time at which the inductor current would reach a predetermined current limit if the inductor current continued to increase at the ramp-up rate. The control loop then receives the timing signal and compares the target time to the end of the ramp time. The pulse width of the inductor switch control signal is increased when the target time occurs after the end of the ramp time. Adjusting the frequency and pulse width controls the peak of the inductor current. | 10-23-2008 |
| 20080259654 | Compensating for cord resistance to maintain constant voltage at the end of a power converter cord - A cord correction circuit in a primary-side-controlled flyback converter compensates for the loss of output voltage caused by the resistance of the charger cord. In one embodiment, a correction voltage is subtracted from a feedback voltage received from a primary-side auxiliary inductor. A pre-amplifier then compares a reference voltage to the corrected feedback voltage. In another embodiment, the correction voltage is summed with the reference voltage, and the pre-amplifier compares the feedback voltage to the corrected reference voltage. The difference between the voltages on the input leads of the pre-amplifier is used to increase the output voltage to compensate for the voltage lost through the charger cord. The flyback converter also has a comparing circuit and a control loop that maintain the peak level of current flowing through the primary inductor of the converter. Adjusting the frequency and pulse width of an inductor switch signal controls the converter output current. | 10-23-2008 |
| 20080259656 | Regulating output current from a primary side power converter by clamping an error signal - An inductor current flows through an inductor of a flyback converter. In a constant voltage mode, the pulse width of an inductor switch control signal is adjusted to maintain a constant output voltage of the flyback converter. The inductor switch control signal controls a switch through which the inductor current flows. In a constant current mode, a comparing circuit, a control loop and a clamp generator circuit are used to maintain the peak level of inductor current. The comparing circuit generates a timing signal based on the ramp-up rate of the inductor current. The control loop uses the timing signal and a feedback signal to generate a time error signal. The clamp generator circuit uses the time error signal to generate a clamp signal that adjusts the pulse width of the inductor switch control signal to clamp the peak current output by the flyback converter in the constant current mode. | 10-23-2008 |
| 20090016086 | Secondary side constant voltage and constant current controller - A low-cost integrated circuit is used as a secondary side constant voltage and constant current controller. The integrated circuit has four terminals and two amplifier circuits. A first amplifier circuit is used to sense a voltage on a FB terminal and in response to cause a first current to flow through an OPTO terminal. A second amplifier circuit is used to sense a voltage between a SENSE terminal and a SOURCE terminal and in response to cause a second current to flow through the same OPTO terminal. The FB terminal is used for output voltage feedback and is also used to supply power onto the integrated circuit. The SOURCE terminal is used for output current feedback and is also used as power supply return for the integrated circuit. The cost of the integrated circuit is reduced by having only four terminals. | 01-15-2009 |
| 20090091953 | Compensating for inductance variation in a power converter using a dual-purpose feedback pin - A comparing circuit and a control loop are used to maintain the peak level of current flowing through an inductor of a flyback converter. An inductor switch control signal controls an inductor switch through which the inductor current flows. The inductor current increases at a ramp-up rate during a ramp time and stops increasing at the end of the ramp time. The comparing circuit generates a timing signal that indicates a target time at which the inductor current would reach a predetermined current limit if the inductor current continued to increase at the ramp-up rate. The control loop then receives the timing signal and compares the target time to the end of the ramp time. The pulse width of the inductor switch control signal is increased when the target time occurs after the end of the ramp time. Adjusting the pulse width controls the peak of the inductor current. | 04-09-2009 |
| 20090207636 | Constant current and voltage controller in a small package with dual-use pin - A comparing circuit and a control loop are used to maintain the peak level of current flowing through an inductor of a flyback converter. An inductor switch control signal controls an inductor switch through which the inductor current flows. The inductor current increases at a ramp-up rate during a ramp time and stops increasing at the end of the ramp time. The comparing circuit generates a timing signal that indicates a target time at which the inductor current would reach a predetermined current limit if the inductor current continued to increase at the ramp-up rate. The control loop then receives the timing signal and compares the target time to the end of the ramp time. The pulse width of the inductor switch control signal is increased when the target time occurs after the end of the ramp time. Adjusting the pulse width controls the peak of the inductor current. | 08-20-2009 |
| 20110074352 | Compensating for cord resistance to maintain constant voltage at the end of a power converter cord - A cord correction circuit in a primary-side-controlled flyback converter compensates for the loss of output voltage caused by the resistance of the charger cord. In one embodiment, a correction voltage is subtracted from a feedback voltage received from a primary-side auxiliary inductor. A pre-amplifier then compares a reference voltage to the corrected feedback voltage. In another embodiment, the correction voltage is summed with the reference voltage, and the pre-amplifier compares the feedback voltage to the corrected reference voltage. The difference between the voltages on the input leads of the pre-amplifier is used to increase the output voltage to compensate for the voltage lost through the charger cord. The flyback converter also has a comparing circuit and a control loop that maintain the peak level of current flowing through the primary inductor of the converter. Adjusting the frequency and pulse width of an inductor switch signal controls the converter output current. | 03-31-2011 |
