Surface-mount 1.2 to 40 V LDO can easily be paralleled

Pity the poor low dropout regulator (LDO). It's been around since the mid-1970s, gets little respect due its assumed low efficiency, is available in literally thousands of versions, so who needs another one? And what sort of substantial innovation is possible with this mundane, well-explored device?

Linear Technology Corp (LTC) says there's room for another, radically different LDO. The LT3080 is a 1.1 A device with 300 mV dropout at full load; it accepts inputs from 1.2 to 40 V, and has adjustable output (via a single resistor) of 40 V down to 0 V (useful for asserting a power-down function). An internal 1% reference yields high output accuracy for LDO, and wideband noise is 40 μVrms to 100 kHz. It is available in a variety of packages including surface mount DFN, MSOP, and SOT-223, as well as thru-hole TO-220.

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But the total LDO story doesn't end there. Due to its new internal design (which is transparent to the user), this LDO can be paralleled with other LT3080s for greater output current capability (while maintaining an all-SMT LDO function). All that is required to use multiple regulators is a small length of PCB trace, approximately 1 cm (10 mΩ), which functions as the LDO ballast. The LT3080 needs two external capacitors; they can be low-cost ceramic versions. Depending on package, the LT3080 is priced between $1.88 and $2.20 each, in 1000-piece orders.

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For more information, contact Linear Technology Corp., Milpitas, CA.—Bill Schweber

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