The TPS65251 features three synchronous wide input range high efficiency buck converters.
The converters are designed to simplify its application while giving the designer the option to
optimize their usage according to the target application.The converters can operate in 5-, 9-, 12- or 15-V systems and have integrated power
transistors. The output voltage can be set externally using a resistor divider to any value between
0.8 V and close to the input supply. Each converter features enable pin that allows a delayed
start-up for sequencing purposes, soft-start pin that allows adjustable soft-start time by choosing
the soft-start capacitor, and a current limit (RLIMx) pin that enables designer to adjust current
limit by selecting an external resistor and optimize the choice of inductor. The current mode
control allows a simple RC compensation.The switching frequency of the converters can either be set with an external resistor
connected to ROSC pin or can be synchronized to an external clock connected to SYNC pin if needed.
The switching regulators are designed to operate from 300 kHz to 2.2 MHz. 180° out of phase
operation between Buck 1 and Buck 2, 3 (Buck 2 and 3 run in phase) minimizes the input filter
requirements.TPS65251 features a supervisor circuit that monitors each converter output. The PGOOD pin
is asserted once sequencing is done, all PG signals are reported and a selectable end of reset time
lapses. The polarity of the PGOOD signal is active high.TPS65251 also features a light load pulse skipping mode (PSM) by allowing the LOW_P pin
tied to V3V. The PSM mode allows for a reduction on the input power supplied to the system when the
host processor is in standby (low-activity) mode.
