Hot Swap Controller Eliminates Software Interfaces
Linear Technology’s LTC4242 is a dual-slot PCI Express Hot Swap controller for mid-range networking or storage servers and embedded applications. The device simplifies the application by eliminating complex software interfaces, yet provides a rugged and compact solution for independently controlling the main supplies (12 V and 3.3 V) and the auxiliary (3.3-V AUX) supply on two slots. Each supply is continuously monitored for undervoltage and overcurrent faults. The 12-V supply inputs are protected up to 20 V. Together with analog current-limit amplifiers, electronic circuit breakers with adjustable response time provide dual-level overcurrent protection.
Control for the auxiliary supplies is completely independent with separate ON and FAULT pins. The internal 3.3-V AUX MOSFET features a 0.25-Ω on resistance. This together with the exposed backside metal on the QFN package and thermal shutdown protection minimizes heat in the device. A separate VCC pin allows the part to power up without the main supplies being present and the ability to ride out glitches in the auxiliary supply.
The 5-mm x 7-mm QFN package is narrow enough to fit between the PCI Express connectors if needed for board space optimization. The optional leaded package, 36-pin SSOP, is a proprietary package designed for narrow applications, requiring less than 8 mm, including the landing area for the pins.
Available now, pricing begins at $3.30 each in 1000-piece quantities. For more sophisticated monitoring, the single-slot LTC4245 includes an integrated ADC and I2C interface for high-end PCI Express applications.