LX5240CDB数据手册Microchip中文资料规格书

描述 Description

Key Features:
• Auto-Selectable LVD OrSingle-Ended Termination
• 3.0pF Maximum Disabled OutputCapacitance
• Fast Response, No External CapacitorsRequired
• Compatible With Active NegationDrivers
• 15µA Supply Current In DisconnectMode
• Logic Command Disconnects AllTermination Lines
• Diffsense Line Driver
• Ground Driver Integrated For Single-EndedOperation
• Current Limit And Thermal Protection
• Hot-Swap Compatible(Single-Ended)
• Compatible With SCSI 1, 2, 3, Fast-20,And The Pending SPI-2 LVD
• Plug And Play Compatible
• See LX5245/5246, LVD Termination OnlyThe LX5240 is a multimode SCSI terminator with plug-and-play capability that conforms to the SCSI Parallel Interconnect-2 (SPI-2) specification developed by the T10 standards committee for low voltage differential (LVD) termination, while providing backwards compatibility to the SCSI, SCSI-2, and SPI single-ended specifications. Multimode compatibility permits the use of legacy devices on the bus without hardware alterations. Automatic mode selection is achieved through voltage detection on the diffsense line. The LX5240 utilizes Linfinity’s UltraMAX technology which delivers the ultimate in SCSI bus performance while saving component cost and board area. Elimination of the external capacitors also mitigates the need for a lengthy capacitor selection process. The individual high bandwidth drivers also maximize channel separation and reduce channel to channel noise and cross talk. The high bandwidth architecture insures ULTRA2 performance while providing a clear migration path to ULTRA3 and beyond. When the LX5240 is enabled, the differential sense (DIFFSENSE) pin supplies a voltage between 1.2V and 1.4V. In application, this pin is tied to the DIFFSENSE input of the corresponding LVD transceivers. This action enables the LVD transceiver function. DIFFSENSE is capable of supplying a maximum of 15mA. Tying the DIFFSENSE pin high places the LX5240 in a HI Z state indicating the presence of an HVD device. Tying the pin low places the part in a single-ended mode while also signaling the multimode transceiver to operate in a single-ended mode. The LX5240 supports full Plug and Play functionality with the DISCONNECT A and B pins. These logic compatible pins place the device in operational or sleep modes. During sleep mode, power dissipation is reduced to a meager 15µA while also placing all outputs in a HI Z state. Also during sleep mode, the DIFFSENSE function is disabled and is placed in a HI Z state.Another key feature of the LX5240 is the master / slave function. Driving this pin high or floating the pin enables the 1.3V DIFFSENSE reference. Driving the pin low disables the on board DIFFSENSE reference and enables use of an external master reference device.