| 摘要 |
A DC to DC switching regulator includes a first pulse width modulator (PWM) (26) and two switching transistors (48) and (50) that are coupled to a transformer (18) to generate an output signal that has pulse widths variable in response to the PWM (26). The output of the transformer (18) is rectified to provide a regulated DC output. A second PWM (78) is provided to convert the amplitude of the regulated DC output to a stream of pulses that are input to an isolation transformer (112) by a push-pull arrangement of transistors (118) and (120). The pulse width of the pulses input to the isolation transformer (112) is variable as a function of the level of the regulated DC and the amplitude thereof is a constant referenced to the internal reference of the PWM (78). The output of the isolation transformer (112) is rectified and filtered to provide an error signal that varies in response to the pulse width of the output pulses from the PWM (78). The constant amplitude, variable width pulses output by the PWM (78) provides a signal that does not vary in response to noise on the regulated DC output and the error signal derived therefrom is input to the PWM (26) to vary the pulse width thereof to maintain regulation on the regulated DC output.
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