The TPS40197 is a synchronous buck controller that operates from 4.5 V to 14 V input
supply nominally. The controller implements voltage-mode control architecture with the switching
frequency fixed at 520 kHz. The higher switching frequency facilitates the use of smaller inductor and output capacitors, thereby providing a compact power-supply solution. An adaptive anti-cross conduction scheme is used to prevent shoot through current in the power FETs.
The TPS40197 integrates the PWM control and 4-bit VID interface in a single chip to
allow seamless on-the-fly VID changes with programmable transition rate. It provides a simple power
solution for Smart-Reflex™ DSP cores.
Short circuit detection is done by sensing the voltage drop across the low-side FET
when it is on and comparing it with a user selected threshold of 100 mV, 200 mV or 280 mV. The
threshold is set with a single external resistor connected from COMP to GND. This resistor is
sensed at startup and the selected threshold is latched. Pulse by pulse limiting (to prevent
current runaway) is provided by sensing the voltage across the high-side FET when it is on and
terminating the cycle when the voltage drop rises above a fixed threshold of 550 mV. When the
controller senses an output short circuit, both FETs are turned off and a timeout period is
observed before attempting to restart. This provides limited power dissipation in the event of a
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