TPS40192 and TPS40193 are cost-optimized synchronous buck controllers that operate from
4.5 V to 18 V input. These controllers implement a voltage-mode control architecture with the
switching frequency fixed at either 600 kHz (TPS40192) or 300 kHz (TPS40193). 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.
Short circuit detection is done by sensing the voltage drop across the low-side MOSFET
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 MOSFET 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 MOSFETs are turned off and a timeout period is
observed before attempting to restart. This behavior provides limited power dissipation in the
event of a sustained fault.
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