Santa Clara, Calif. National Semiconductor Corp. has squeezed its LM4871 bridge-connected Boomer audio amplifier into a leadless lead frame package (LLP) about half the size of the small-outline package it had been using.
Steve Kaufman, marketing manager for National's audio amplifier product group, said the new package enables the part to drive a speaker with an output of up to 2.4 watts at 3 ohms and 1 percent total harmonic distortion, and to operate from power supplies as low as 2 volts. The SOP package had limited the amplifier to 1.1 watts at 8 ohms.
"Board space is extremely valuable-to makers of cell phones especially-because the products are getting smaller, and because manufacturers are providing more functionality," Kaufman explained.
"One of the major trends in cell phones is to add features like FM radio or an MP3 player, and another is the growing importance of hands-free operation for safety reasons. Both trends make it critical for sound-system components to shrink in size at the same time they increase in output capacity." In addition to cell phones, the LM4871 can be used in information appliances and notebook and desktop computers.
Kaufman said it was the SOP package and not the LM4871 die that limited the part's output. The leadless package has an exposed die attach pad (DAP) that dissipates heat more efficiently. National is making extensive use of the LLP package across its entire analog product line, but Kaufman said the LM4871 is the first product to take full advantage of the exposed DAP.
"The LLP is revolutionary in terms of its small footprint and high power dissipation capabilities, and will enable our customers to design-in audio solutions in half the size of previous solutions with no loss of performance," he said.
The LM4871 has a shutdown mode that reduces supply current consumption to less than 1 microamp (typical) and eliminates the need for an external FET. An internal thermal-shutdown mechanism protects the device from overheating.
Kaufman said the device also features circuitry to suppress the pops and clicks often associated with turn-on or turn-off. It operates without the aid of bootstrap capacitors or snubber networks. National's LM4871 in the LLP is priced at 95 cents in quantities of 1,000.
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EETInfo No. 613