JAJSOR8 September 2024 LM70840 , LM70860 , LM70880
PRODUCTION DATA
The LM708x0 includes an output voltage monitoring signal for VOUT to simplify sequencing and supervision. The power-good function can be used to enable circuits that are supplied by the corresponding voltage rail or to turn on sequenced supplies. The power-good output (PG) switches to a high impedance open-drain state when the output voltage is in regulation. The PG output switches low when the corresponding output voltage drops below the lower power-good threshold (92% typical) or rises above the upper power-good threshold (110% typical). If the upper PG threshold is exceeded when operating in standalone configuration mode, the high-side switch is turned off immediately and the low-side switch is turn on to prevent overvoltage and discharge the output. A 25µs deglitch filter prevents false tripping of the power-good signal during transients. TI recommends a pull-up resistor of 100kΩ (typical) from PG to the relevant logic rail. PG is asserted low during soft-start and when the buck regulator is disabled via the EN input.
When the LM708x0 is configured as a primary device, the PG pin is converted to a synchronization clock output for the secondary device. The synchronization signal has logic levels and is 180° out of phase (lagging) with the internal high-side gate driver output of the primary device.