SNVSAH5A September 2017 – May 2020 LM73605 , LM73606
PRODUCTION DATA.
In CCM operation, inductor current has a continuous triangular waveform. The HS switch is on at the beginning of a switching cycle and the LS switch is turned off the end of each switching cycle. In auto mode, the LM73605 and LM73606operate in CCM when the load current is higher than ½ of the peak-to-peak inductor current (ILripple). In FPWM mode, the LM73605 and LM73606operate in CCM, regardless of load.
In CCM operation, the switching frequency is typically constant, unless tON-MIN, tOFF-MIN, or IPEAK-MIN conditions are met. The constant switching frequency is determined by RT pin setting, or the external synchronization clock frequency. The duty cycle is also constant in CCM: D = VOUT / VIN if loss is ignored, regardless of load. The peak-to-peak inductor ripple is constant with the same VIN and VOUT, regardless of load.
With very high or very low supply voltages, when the tON-MIN or tOFF-MIN condition is met, the frequency reduces to maintain VOUT regulation with even higher or lower VIN, respectively. When the IPEAK_MIN condition is met in auto mode, the switching frequency folds back to provide higher efficiency. IPEAK_MIN is disabled in FPWM mode.