Charge pump with controlled ramp rate

摘要

A charge pump with controlled ramp rate (200) includes a charge pump (65), an RC differentiator circuit (258), and a trigger circuit (238). The charge pump (65) receives a clock signal and provides a high output voltage for programming and erasing an EEPROM. The RC differentiator circuit (258) provides a control voltage that is proportional to the ramp-up rate of the high output voltage. The trigger circuit (238) receives the control voltage, and provides a control signal to disable the charge pump (65) if the ramp-up rate exceeds a predetermined rate. When the ramp-up rate falls below the predetermined rate, the trigger circuit (238) provides a control signal to enable the charge pump (65). The trigger circuit (238) has hysteresis to regulate its switching point. Controlling the ramp-up rate of the output voltage reduces the peak tunneling current in the EEPROM cell to increase reliability.