The LM25149-Q1 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 controller is disabled.

When the LM25149-Q1 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.