Linear Technology announced the H-Grade version of the LT3686. The LT3686H is a 1.2A, 37VIN step-down switching regulator. The device operates within a VIN range of 3.6V to 37V with overvoltage lockout, protecting the regulator and load from transients as high as 55V, making it ideal for load dump and cold-crank conditions commonly found in automotive applications as well as 24V industrial supplies. Its internal 1.85A switch can deliver up to 1.2A of continuous output current at voltages as low as 0.8V.
Cycle-by-cycle current limit and DA current sense provide protection against fault conditions. Soft-start and frequency foldback eliminate input current surge during start-up. An optional internal regulated active load at the output via the BD pin keeps the LT3686H at full switching frequency at light loads, resulting in low, predictable output ripple above the audio and AM bands. Internal compensation and an internal boost diode reduce external component count.
The LT3686H's switching frequency is user programmable from 300kHz to 2.5MHz, enabling designers to maximize efficiency while avoiding critical noise-sensitive frequency bands such as the AM broadcast band. Its low minimum on-time enables it to provide high switching frequencies even with high step-down ratios. For example, with an input as high as 16V, it can deliver a 3.3V output using a 2MHz switching frequency. The LT3686H also uses a unique design, which ensures that it maintains constant frequency switching, even in very light load conditions. The device's 3mm x 3mm DFN-10 package and high switching frequency, which keeps the external inductor and capacitors small, provides a compact, thermally efficient footprint. The H-grade version operates up to a junction temperature of 150?C, compared to the E and I grade versions' 125?C maximum junction temperature. All electrical specifications are identical for the E, I and H grade versions. The H-grade versions are tested and guaranteed to the maximum junction temperature of 150?C, making them especially suited to automotive and industrial applications which are subjected to high ambient temperatures.
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