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Surface-mount LDO is easily paralleled

Posted: 25 Jul 2007 ?? ?Print Version ?Bookmark and Share

Keywords:low dropout regulator? capacitors? surface-mount LDO?

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

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 1cm (10m), which functions as the LDO ballast. LT3080 needs two external capacitors; they can be low-cost ceramic versions. Depending on package, LT3080 is priced between $1.88 and $2.20 each, in 1000-piece orders.

- Bill Schweber
Planet Analog

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