Telecom, industrial, avionic, and automotive applications are targets of Linear Technology’s LTC3638, a 140-V, input-capable buck converter that offers up to 250 mA of continuous output current. Input voltage ranges from 4 to 140 V. Internal synchronous rectification and a programmable hysteretic-mode design help optimize efficiency over a broad range of output currents—efficiencies reach as high as 88%. It requires a mere 12 µA of quiescent current to maximize battery run time. A user-programmable output-current limit can be set from 20 to 250 mA, per application requirements. The converter is programmable with fixed output voltages of 1.8, 3.3, or 5 V, or a resistor divider can be used to program outputs from 0.8 V to VIN. No external compensation is required. Other features include a precise, 0.8-V ±1% feedback voltage reference, internal or external soft-start, and a feedback comparator output. The LTC3638 comes in a thermally enhanced skipped-lead MSOP package.