556 Voltage-Controlled Duty Cycle

556 Volt.-Controlled Duty Cycle. When the input voltage is at 0 V the CONTROL voltage is at ½Vcc. With ramp (rising half portion of triangular) input signal the CONTROL voltage varies from ¼Vcc to 3/4 Vcc. With VCVS at the input the CONTROL voltage varies only from ½Vcc to 3/4 Vcc. When the input voltage is at -Vcc: CONTROL voltage = ¼Vcc Output pulse width = ln(4/3) · RC = 146.718 µs When the input voltage is at 0 V: CONTROL voltage = ½Vcc Output pulse width = ln(2) · RC = 353.505 µs When the input voltage is at Vcc: CONTROL voltage = 3/4 Vcc Output pulse width = ln(4) · RC = 707.010 µs The relationship between the change in input voltage and change in output pulse width is not linear.