| 摘要 |
PROBLEM TO BE SOLVED: To provide a PWM circuit device capable of improving responsiveness to drastic fluctuation in input/output and current capacity by increasing the maximum duty. SOLUTION: The PWM circuit device wherein a coil load (5) is PWM-driven to output an output voltage (E) comprises an error amp (8) to compare a reference voltage (REF1) with the output voltage (E), a minimum value circuit (3) which compares the output (C) from the error amp (8) with the other input (B) to output the lower voltage of both of them, an oscillator (1) outputting reference frequency (F), a comparator (2) to compare the output from the minimum value circuit (3) with the output from the oscillator (1), a counter (9) using the output (D) from the comparator and the output from the oscillator (1) to count the output from the comparator (2), and a reference voltage source generating circuit (14) to vary the output voltage corresponding to the output from the counter (9). The output from the reference voltage source generating circuit (14) is applied as the other input of the minimum value circuit (3) to drive the coil load (5) with the signal on the output side of the comparator (2). COPYRIGHT: (C)2005,JPO&NCIPI
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