13.24.1.1 Charge Pump Capacitors

Figure 13-7. Charge Pump

Let:

  • IOUT = 20 mA
  • fCP = 75 kHz (charge/discharge in one cycle)
  • 50% duty cycle
  • VDDH = 5.5V (worst case)
    • RDSON = 7.5Ω (RPMOS), 3.5Ω (RNMOS)
    • V12P = 2 × VDDH (ideal)
    • CESR = 20 mΩ (ceramic capacitors)
    • VDROP = 100 mV (VOUT ripple)
    • TCHG = TDCHG = 0.5 × 1/75 kHz = 6.67 µs