JAJSRI9A October 2023 – March 2024 LM51772
ADVANCE INFORMATION
With the MODE pin low, power save mode is active. In this operating mode, the switching activity is reduced and efficiency is maximized. If the mode pin is high, power save mode is disabled. The converter operates in continuous conduction mode.
In boost or in buck mode, the converter is operating up to the duty cycles with the respective minimum off times or on times. If the timing limits are reached, the output voltage increases. As soon as this happens, the voltage regulation loop detects the increase and turns the device into a TI proprietary sleep mode as the energy consumed by the load is less than what the converter generates during switching. In this mode, both low sides are turned on to provide the high-side gate supply for HB1 and HB2 are charged. Other internal circuits are partially turned off to reduce the current consumption of the converter to a minimum possible. In case the output voltage reaches the nominal output voltage set point, the switching activity starts again.
In the buck-boost area where larger or smaller duty cycle is necessary, switching pulses are skipped. When necessary, the control initiates switching activities with a minimum time of state I or state III to maintain the inductor current as required by the voltage regulation loop.
If you intend operate in Buck operation with on-times smaller than ≈300ns and light load conditions, the recommendation is to turn-on the SYNC output instead of using the SYNC input function to provide low inductor current ripple.