| 摘要 |
PURPOSE: A charge pump for a voltage pump converter is provided, which prevents a fail at a low VEXT, by making a smooth chip operation at the low VEXT which occurs during a power down/up. CONSTITUTION: A pair of PMOS transistor are connected between the first and the second boot node and a VPP node in a cross type. The first and the second boot capacitor are connected to the first and the second boot node respectively and receive different clocks as inputs. The second NMOS transistor is connected between the first boot node and an external power supply, and is connected to the external power supply through the first NMOS transistor whose gate is connected to the third boot node and the voltage source. The fourth NMOS transistor is connected between the second boot node and the external power supply and is connected to the external voltage source through the third transistor whose gate is connected to the fourth boot node and the voltage source. The third and the fourth boot capacitor are connected to the third and the fourth boot node and receive different clocks as inputs. And a discharge part discharges voltages of the third and the fourth boot node during a power up or down.
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