Ultra3 LVD/SE SCSI 14-Line Terminator

The DS2127 Ultra3 LVD/SE SCSI terminator provides low-voltage differential (LVD)/single-ended (SE) terminations for 14 SCSI lines. Through the voltage on the DIFFCAP pin, the device detects the types of drivers on the bus. If the device is connected in an LVD-only bus, the DS2127 provides LVD termination. If any single- ended devices are connected to the bus, the DS2127 uses SE termination. If any high-voltage differential (HVD) devices are connected to the bus, the DS2127 isolates itself from the SCSI bus. The mode change has a built-in delay that is determined by an integrated SPI-3 mode change filter/delay. The terminating resistors can also be disconnected from the bus by asserting the ISO pin.

For the LVD termination, the DS2127 provides 14 precisely trimmed resistors. Each resistor is biased with two current sources to a fail-safe state. For SE termination, the DS2127 provides 14 precision 110Ω resistors and one regulator for active-negation bias.

Applications

* SCSI Array Backplane * SCSI Cables

* Fully Compliant with Ultra2, Ultra3, Ultra160, and Ultra320 SCSI Standards

* Provides LVD/SE Termination for 14 Signal Pairs

* Auto-Selection of LVD or SE Termination

* 5% Tolerance on SE and LVD Termination Resistance

* Low 3pF Power-Down Capacitance

* Built-In Mode-Change Filter/Delay

* On-Board Thermal-Shutdown Circuitry

* SCSI Bus Hot-Plug Compatible

* Fully Supports Actively Negated SE SCSI Signals