Switching techniques to reduce current overshoot in a DC to DC converter
AssigneeFairchild Semiconductor Corporation
InventorHangseok Choi
Life of this patent
Estimating the term…
Abstract
A DC/DC converter system includes gate control circuitry, a transformer, a second stage, and soft start control circuitry. The gate control circuitry is configured to generate a first and a second gate control signal configured to open and close first and second switches of an inverter circuitry, respectively, to generate an AC signal from a DC input signal. The transformer transforms the AC signal and the second stage rectifies the AC signal to a DC output signal. The soft start control circuitry generates a signal to delay a closing of the first switch during an initial portion (Td) of a first cycle of the first switch. A method of soft-starting a DC/DC converter includes generating first and second gate control signals and delaying closing of the first switch during Td.
Claims16
A DC to DC converter system, comprising:
- gate control circuitry including inverter circuitry having a first and a second switch, the gate control circuitry further configured to generate a first and a second gate control signals configured to open and close the first and the second switch, respectively, and generate an AC signal from a DC input signal;
- a transformer configured to transform the AC signal;
- a second stage configured to rectify the AC signal to a DC output signal;
- current controlled oscillator circuitry configured to sequentially charge and discharge a pulse frequency modulated capacitor (PFMcap) such that the voltage (VCT) of PFMcap oscillated between a high voltage threshold (VTH) and a low voltage threshold (VTL) in a triangular waveform;
- and
- soft start control circuitry configured to generate a signal to delay a closing of the first switch during an initial portion (Td) of a first cycle of the first switch based on the VCT signal, a clock signal (CLK), and a run signal (RUN), the soft start control circuitry including a timing block configured to generate an initialization signal (INITIALIZE) for a predetermined amount of time (Ti) upon startup of the DC to DC converter system, the timing block further configured to generate the RUN signal after Ti.
A method of soft-starting a DC to DC converter, the method comprising:
- generating a first and a second gate control signal configured to open and close a first and a second switch of an inverter circuitry, respectively;
- sequentially charging and discharging a pulse frequency modulated capacitor (PFMcap) such that the voltage (VCT) of PFMcap oscillates between a high voltage threshold (VTH) and a low voltage threshold (VTL) in a triangular waveform;
- and
- delaying a closing of the first switch during an initial portion (Td) of a first cycle of the first switch based on the VCT signal, a clock signal (CLK), and a run signal (RUN), wherein an initialization signal (INITIALIZE) is generated for a predetermined amount of time (Ti) upon startup of the DC to DC converter system, and wherein the RUN signal is generated after Ti.
Dependencies are inferred from the claim text.