| 摘要 |
A charge pump circuit is provided to make the settling time short by shortening the time to the time in which the step-up voltage reaches the desired step-up voltage from the voltage after the overshoot. A charge pump circuit comprises a voltage booster circuit(21), a voltage level detection circuit, an oscillator circuit(20) and a discharge circuit(42). The voltage booster circuit boosts the voltage and outputs the step-up voltage based on the pumping pulse outputted from an oscillator circuit. The voltage level detection circuit operates to make step-up voltage reach the desired voltage. If the step-up voltage is under the desired voltage, the voltage level detection circuit controls the oscillator circuit to operate. If the step-up voltage is over the desired voltage, the voltage level detection circuit controls the oscillator circuit make it stop. In the operation of the oscillator circuit, it outputs the pumping pulse to make the voltage booster circuit operate to boost the voltage, in the stop of the oscillator circuit operation, it does not output the pumping pulse. The discharge circuit does not discharge an output terminal of the charge pump circuit, if the step-up voltage is under the overshoot. If it is over the overshoot, the discharge circuit discharges the output terminal of the charge pump circuit.
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