7.1 Overview

The LM25118 high voltage switching regulator features all of the functions necessary to implement an efficient high voltage buck or buck-boost regulator using a minimum of external components. The regulator switches smoothly from buck to buck-boost operation as the input voltage approaches the output voltage, allowing operation with the input greater than or less than the output voltage. This easy-to-use regulator integrates high-side and low-side MOSFET drivers capable of supplying peak currents of 2 A. The regulator control method is based on current mode control using an emulated current ramp. Peak current mode control provides inherent line feedforward, cycle-by-cycle current limiting and ease-of-loop compensation. The use of an emulated control ramp reduces noise sensitivity of the pulse-width modulation circuit, allowing reliable processing of very small duty cycles necessary in high input voltage applications. The operating frequency is user programmable from 50 kHz to 500 kHz. An oscillator synchronization pin allows multiple LM25118 regulators to self synchronize or be synchronized to an external clock. Fault protection features include current limiting, thermal shutdown, and remote shutdown capability. An undervoltage lockout input allows regulator shutdown when the input voltage is below a user selected threshold, and a low state at the enable pin will put the regulator into an extremely low current shutdown state. The device is available in the 20-pin HTSSOP package featuring an exposed pad to aid in thermal dissipation.