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Protection switch aimed at portable, adapter-powered devices

Posted: 11 Aug 2014 ?? ?Print Version ?Bookmark and Share

Keywords:Texas Instruments? FET? protection switch? power management unit? portable?

Texas Instruments (TI) has rolled out what it says is the industry's smallest bidirectional 18V, 5A protection switches with high power efficiency. According to the company, the small devices cut solution size and extend battery life in portable and adapter-powered devices, and enterprise and client solid state drives (SSDs).

Enterprise SSDs are reading and writing more data than ever before, which is driving a requirement for increased speed and reliability in smaller form factors. TI's TPS25940 and TPS25942 ICs include back-to-back FETs to provide bidirectional current control, while reducing system size by 50 per cent compared to discrete solutions. The smart eFuse ICs save board space by maintaining over/under voltage threshold accuracy of two per cent, eliminating the need for a separate supply voltage supervisor chip.


The TPS25940 eFuse power switch integrates DevSleep mode, which enables hosts and devices to completely hibernate an SSD serial ATA (SATA) interface to reduce power consumption to less than 5mW. The TPS25942 eFuse power multiplex (MUX) integrates an enable block function that allows the system to select between non-ideal diode mode and ideal diode mode.

The TPS2594x devices extend battery life and reduce power loss. In addition to DevSleep mode, the smart-eFuse devices integrate an active mode to reduce power consumption by providing an internal low-resistance switch (42m? typical). The switches also boast fast short-circuit response of 200ns that minimises bus droop and supply stress during short-circuit events. They also allow two supplies of equivalent voltage to be designated primary and secondary without turning off the overcurrent protection NFET of either, which reduces holdup capacitor requirements by up to 70 per cent.

TI also introduced a power management unit (PMU) with six integrated buck regulators designed for the SandForce SF3700 SSD controllers for notebooks and PCs. The LM10692 provides phase-shifted operation at 2MHz switching frequency to reduce the input-current ripple. In addition, the integrated PMU cuts inductor and capacitor size to save valuable board space. Using TI's LM10692 and MSP430 with SandForce's SF3700 controller reduces system size to a tiny 13.5 x 9.3mm footprint. As part of this collaboration, TI joined the SandForce Trusted program in order to provide premium support and enable faster time-to-market for customers using TI solutions with the SandForce controller.

These SSD power management devices are shipping in volume production in the following package options and prices in 1,000-unit quantities: TPS25940 eFuse power switch: 20-pin, WQFN package at $0.85; TPS25942 eFuse power MUX: 20-pin, WQFN package at $1.10, and LM10692 PMU: 36-pin, VQFN package at $2.80.

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