| 摘要 |
PROBLEM TO BE SOLVED: To stably generate a high precision PWM signal even in an overvoltage input condition.SOLUTION: In a pulse width modulation scheme adapted to perform, in integration circuits 4, 5, a charge/discharge operation of charge with a current i=I+G*|e| for half a period (T/2) of a reference clock MCLK and subsequent discharge of a constant current, alternately with a shift of half the period, generate in flip-flop circuits 7, 8 pulse signals /S1, /S2 of a pulse width equivalent to a discharge time tof the integration circuits 4, 5, respectively, and combine in a pulse signal combination circuit 11 both pulse signals to generate a PWM signal S, when voltage levels V1, V2 of the integration circuits 4, 5 are clipped at a reference level Vin a negative overvoltage condition, switch circuits SW2, SW3 are turned off to prohibit the discharge operation of the integration circuits 4, 5. |
