Digital Soft Start

Uses Up Counter, DAC and Bus Comparator

  1. Counter counts PWM clocks
  2. Maximum count = MAX_COUNT = T_SS*SW_FREQ. For a 1ms SS @ 500kHz, MAX_COUNT = 500
  3. Need 10 bits = max SS ramp time = 1023/SW_FREQ = 2.046ms
  4. DAC LSB = 1mV, Max Vss = 600mV
  5. Therefore we need to scale DAC output with VCVS