The TPS40345 is a synchronous buck controller that operates from 3-V to 20-V input and
which can be used in cost-optimized applications. The controller implements a voltage-mode control
architecture with input-voltage feed-forward compensation that responds instantly to a change in
input voltage. The switching frequency is fixed at 600 kHz.The frequency spread spectrum (FSS) feature adds to the switching frequency,
significantly reducing the peak EMI noise and making it much easier to comply with EMI
standards.The TPS40345 offers design with a variety of user-programmable functions, including
soft-start, overcurrent protection (OCP) levels, and loop compensation.OCP level may be programmed by a single external resistor connected from the LDRV pin to
circuit ground. During initial power on, the TPS40345 enters a calibration cycle, measures the
voltage at the LDRV pin, and sets an internal OCP voltage level. During operation, the programmed
OCP voltage level is compared to the voltage drop across the low-side FET when it is on to
determine whether there is an overcurrent condition. The TPS40345 then enters a shutdown and
restart cycle until the fault is removed.
