An Improved Charge Pump and Its Application in Hot Swap Controller

To prevent charge pump from degradation in its applications to power management IC (integrate circuit) like hot swap controller, the influence of the clock frequency and duty cycle on charge pump was analyzed. And a new oscillator structure featuring the immunity from changes of frequency and duty cycle, which is originated from the supply voltage fluctuation, was proposed. The new charge pump was applied to a hot swap controller IC to lift up the gate drive voltage of the external FET. Simulation results showed that by using it, the hot swap controller worked well while supply voltage swung from 3V to 10V. And all circuits were designed and realized in 1.5μm BCD (Bipolar-CMOS-DMOS) process.