IMP2119

The IMP2119 is a multimode SCSI terminator that conforms to the SCSI Parallel Interconnect-2 (SPI-2) specification developed by the T10 standards committee for low voltage differential (LVD) termination.

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 IMP2119 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 ULTRA3 performance.

When the IMP2119 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 IMP2119 in a high impedance 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 singleended mode.

Recognizing the needs of portable and configurable peripherals, the IMP2119 have a TTL compatible sleep/disable mode. During this sleep/disable mode, power dissipation is reduced to a meager 15µA while also placing all outputs in a high impedance state. Also during sleep/disable mode, the DIFFSENSE function is disabled and is placed in a high impedance state.

Another key feature of the IMP2119 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.