The LM25149 includes an output voltage monitoring signal for V_OUT to simplify sequencing and supervision. The power-good signal is used for start-up sequencing of downstream converters, fault protection, and output monitoring. The power-good output (PG) switches to a high impedance open-drain state when the output voltage is in regulation. The PG switches low when the output voltage drops below the lower power-good threshold (92% typical) or rises above the upper power-good threshold (110% typical). A 25-μs deglitch filter prevents false tripping of the power-good signal during transients. TI recommends a pullup resistor of 100 kΩ (typical) from PG to the relevant logic rail. PG is asserted low during soft start and when the buck regulator is disabled.

When the LM25149 is configured as a primary controller, the PG/SYNC pin becomes a synchronization clock output for the secondary controller. The synchronization signal is 180° out-of-phase with the primary HO driver output.