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New Power Distribution Switches From TI Enable Flexible USB Subsystem DesignSingle-chip USB Power Switches Allow Independent OperationDALLAS (Nov. 9, 1998) -- Designers of Universal Serial Bus (USB) devices for personal computers (PCs) and PC peripherals will have a reliable solution for power distribution and over-current protection with new USB power switches announced today by Texas Instruments (TI). The independent switching capabilities and performance of the switches provide advanced flexibility to designers, allowing them to create more reliable USB designs than alternative methods. The devices are ideal for use in PCs with USB hubs and USB peripherals, such as keyboards, mice and printers. TI’s new USB power distribution switches, designated the TPS204X and TPS205X, feature a patented dual-temperature threshold. This allows multiple switches in a single package to operate independently. Furthermore, each device is capable of shutting down when in over-current without impacting the other switches in the same package. The TPS2041/2/4 devices are single, dual and quad devices and feature negative enable logic, while the TPS2051/2/4 (single/dual/quad) feature positive enable logic. All of these power switch devices offer high reliability and levels of protection for USB-equipped computers and peripherals using them. Other solutions such as polyfuses have been used for over-current protection in USB designs but have a much slower response time to over-current situations, thus risking potential system damage. USB Switches Operate Independently TI’s USB power distribution switches are a true, single-chip solution. The switches are more cost-effective and higher performance than alternative switch approaches. Logic level outputs advise the controller of over-current situations, but the controller is not required to shut down the overloaded switch due to the integrated over-current and temperature protection. These devices have a maximum rDS(on) of 135 milliohms (mohm) over the full operating temperature range of -40 to +125 degrees C. This means that designers have more latitude in their designs, due to less voltage loss across the switch. These devices also meet all USB power distribution specifications. Pricing and Availability The TPS204x and TPS205x device samples and production parts are available now from TI and its authorized distributors. Suggested resale pricing in quantities of 1,000 is in a range from $0.88 to $1.72 (SEE TABLE).
More information about TI’s USB power switch distribution products is available on the World Wide Web at
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