Power: Regulators Reduce Power Consumption Without Redesign

Three high-efficiency step-down voltage regulators are pin- and size-compatible with older and less efficient LM78xx devices. The 78SR regulators can be used as "drop-in" replacements that reduce the power consumption of applications without circuit redesign. Output options are +5 V/0.5 A, +12 V/0.4 A, and +3.3 V/0.5 A. A 260-kHz switching frequency produces efficiencies as high as 95% for the 12-V part and 85% for the 3.3-V and 5-V regulators. Full-load operation from 9-, 12-, 24-, 28-, or 36-V supplies at ambient temperatures as high as 70°C requires no heatsinks, no forced-air cooling, and no temperature derating. Other improvements include lower quiescent current (3 versus 5 mA), higher operating input voltage (36 versus 32 V), and tighter output accuracy (±1.5 versus 5%). A standard vertical-mount SIP occupies less than 645 mm² (0.1 in.²). A horizontal-mount version allows for an installed height of less than 8.9 mm (0.35 in.). Unit pricing in OEM quantities is $4.95.