The TPS40195 is a flexible synchronous buck controller that operates from a nominal 4.5-V
to 20-V supply. This controller implements voltage mode control with the switching frequency
adjustable from 100 kHz to 600 kHz. Flexible features found on this device include selectable
soft-start time, programmable short-circuit limit, programmable undervoltage lockout (UVLO) and
synchronization capability. An adaptive anti-cross conduction scheme is used to prevent shoot
through current in the power FETs. Overcurrent detection is done by sensing the voltage drop across
the low-side MOSFET when it is on, and comparing it with a user-programmable threshold.
The threshold is set with a single external resistor connected from ILIM to GND.
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 provides limited power
dissipation in the event of a sustained fault. Synchronization on this device is bi-directional.
Devices can be synchronized 180° out of phase to a chosen master TPS40195 running at a fixed 250
kHz or 500 kHz, or can be synchronized to an outside clock source anywhere in the 100 kHz to 600
kHz range.
