The TPS40077 is a medium-voltage wide-input (4.5v to 28v) synchronous step-down controller that offers flexible design for a variety of user-programmable functions, including soft start, undervoltage lock (UVLO), operating frequency, voltage feedforward, and high-side FET-induced short-circuit protection. The 16-pin PowerPAD package offers excellent heat dissipation and a compact footprint.
Pin Configuration
The TPS40077 drives an external n-channel mosfet using a second generation predictive gate drive to minimize conduction of the low side FEt-body diode and maximize efficiency. The pre-biased output is supported by not allowing the low-side FETs to open until the voltage of the closed-loop soft-start command is greater than the pre-biased voltage.
Simplified application diagram
Voltage feedforward provides good response to input transients and a constant PWM gain over a wide input voltage operating range to mitigate compensation requirements. Programmable short-circuit protection provides fault current limitation and burp recovery to minimize the power consumption of short-circuit output.
The TPS40077 allows users to construct synchronous voltage-mode step-down converters with inputs ranging from 4.5V to 28V and outputs as low as 700 mV. Predictive gate drive circuits optimize switching delay, increase efficiency and improve converter output power capacity. In wide input range designs, voltage feedforward is used to simplify loop compensation and provide better line transient response. The TPS40077 incorporates circuitry that allows startup to a preexisting output voltage without sinking current from a preexisting output voltage source. This avoids damaging sensitive loads at startup. Integrated power good indicator can be used for the output condition of a logic (leak-open) output converter
Functional Block Diagram
