SNVSB29C October 2018 – June 2021 LM5143-Q1
To synchronize the LM5143-Q1 to an external source, apply a logic-level clock signal (greater than 2 V) to DEMB. The LM5143-Q1 can be synchronized to ±20% of the programmed frequency up to a maximum of 2.5 MHz. If there is an RT resistor and a synchronization signal, the LM5143-Q1 ignores the RT resistor and synchronizes to the external clock. Under low VIN conditions when the minimum off-time is reached, the synchronization signal is ignored, allowing the switching frequency to reduce to maintain output voltage regulation.