US 4,792,746 A · Non-dissipative series voltage switching regulator having improved switching speed

Abstract

A FET switching regulator has a FET switch which is periodically turned on to couple an unregulated DC input voltage to an output filter which develops a regulated output DC voltage. Regulation of the output DC voltage is determined by the on time or duty cycle of the FET switch. A periodic waveform is developed by a pulse-width modulator. The pulse-width modulator compares the input and output DC voltages to a reference voltage to pulse-width modulate the periodic waveform to determine the duty cycle. When the periodic waveform goes high, it triggers a first regenerative circuit which drives the gate of the FET switch into saturation within 20-30 nanoseconds. When the periodic waveform goes low, a second regenerative circuit is triggered to return the FET switch to an off state within 20-30 nanoseconds. Accordingly, the FET switch may be operated at frequencies approaching 500 kHz without excessive power losses within the FET switch in the transitory states between cutoff and saturation. The regenerative circuits may be blocking oscillators.

Claims14

Dependent claims

In a switching regulator having output filter means for generating a smoothed output voltage from an unregulated input DC voltage, transistor switch means for periodically coupling an unregulated input DC voltage to said output filter means, and means for developing a periodic waveform having a duty cycle determined by said output voltage, said transistor switch means coupling said input voltage to said output filter means during the on portion of said duty cycle to regulate said output voltage, the improvement comprising:

first regenerative circuit means comprising a blocking oscillator, said means responsive to said periodic waveform changing state to the on portion of said duty cycle for developing a first signal of increasing magnitude, said switch means turning on in response to said first signal to couple said input voltage to said output filter means;
and
second regenerative circuit means comprising a blocking oscillator, said means responsive to said periodic waveform changing state to the off portion of said duty cycle for developing a second signal of iincreasing magnitude and having a polarity opposite to said first signal, said transistor switch means turning off in response to said second signal.

A FET switching regulator for devolping a regulated output DC voltage from an unregulated input DC voltage including output filter menas for generating said output voltage, a FET switch having a source coupled to said output filter means, a gate and a drain to which said input voltage is applied, and means for generating a periodic waveform having a duty cycle determined as a function of said output voltage, said FET switch being turned an during the on portion of said duty cycle to couple said input voltage to said output voltage, the improvement comprising:

first regenerative circuit means comprising a blocking oscillator, said means responsive to said periodic waveform changing state to the on portion of said duty cycle for developing a first signal and for coupling said first signal to said gate to turn on said FET switch, said first signal having a voltage which continually increases in magnitude until said FET switch goes on;
and
second regenerative circuit means comprising a blocking oscillator, said means responsive to said periodic waveform changing state to the off portion of said duty cycle for developing a second signal and for coupling said second signal to said gate to turn off said FET switch, said second signal having a voltage which continually incerases in magnitude in the opposite polarity with respect to said first signal until said FET switch goes off.

Dependencies are inferred from the claim text.

Non-dissipative series voltage switching regulator having improved switching speed

Life of this patent

Non-dissipative series voltage switching regulator having improved switching speed

Life of this patent

Abstract

Claims14