National Semiconductor Debuts New LM3525/26 USB Power SwitchesFebruary 06, 2000 by Jeff Shepard
National Semiconductor Corp. (Santa Clara, CA) recently introduced the LM3525/26 single- and dual-port USB power switches and protection devices. According to National, the LM3525/26 provides over-current protection and power switching for USB downstream ports. They supply power to a USB tree of devices, notifying their controllers when over-current, over-temperature or under-voltage fault conditions are detected. The addition of an internal delay for the error flag pin enables the elimination of two external components per port (a resistor and capacitor). The company claims the elimination of these components does not affect pin compatibility with competitors' products, but does provide a cost advantage.
"The LM3525 device provides Rds(on) of 120 milliohms worst case, allowing wider tolerance on the power supply and fewer constraints on PCB layout. The LM3526 provides thermal isolation between ports in over-current conditions, preventing good ports from glitching or asserting the error flag pin unnecessarily. Although our customers have many choices in the USB power-switch market, we're taking a lead in innovation by eliminating external parts, while maintaining the compatibility the industry requires in standard USB switches," said James Schuessler, power-management marketing manager for National.
In quantities of 1,000, pricing for the LM3525 in the SO-8 package is $0.75 each, while the LM3526 is priced at $0.90 each.