PWM SIGNAL OUTPUT DEVICE AND SWITCHING POWER SUPPLY DEVICE

Japanese Patent JP2016066861

A

PROBLEM TO BE SOLVED: To provide a PWM signal output device that is enhanced in responsibility by properly clamping a PWM instruction signal at all times.SOLUTION: In a configuration of a PWM signal output device in which a comparator generates and outputs a PWM signal according to the difference between a PWM instruction signal output by an error amplifier 8 and a PWM carrier output by an oscillation circuit 10, an upper limit side clamp for clamping the output voltage of the error amplifier 8 as the PWM instruction signal to an upper limit voltage V, and a lower limit side clamp for clamping the output voltage to a lower limit voltage Vare performed by a series circuit 30 of resistance elements 31 to 35 and amplifiers 28 and 29. Voltages corresponding to the maximum value Vand the minimum value Vof the PWM carrier amplitude are generated by the series circuit 30. An offset voltage is applied to each of the voltages to generate an upper limit voltage V(>V)and a lower limit voltage V(