DS2121A LVD SCSI Terminator is a Low Voltage Differential (LVD) terminator produced by Dalsemi. It supports Ultra2, Ultra3, and Ultra 160 LVD-only SCSI, and can provide LVD termination for 9 signal line pairs. The tolerance on SE and LVD termination resistance is not more than 5%. Its power-down capacitance is only 3 pF. It has onboard thermal shutdown circuitry and is SCSI bus hot plug compatible. It can be widely used in various electronic devices.
The DS2121A is a Low Voltage Differential (LVD) SCSI terminator designed for Ultra2, Ultra3, and Ultra 160 LVD-only SCSI buses. It automatically detects the bus mode (LVD, SE, or HVD) by sensing the voltage on the DIFFSENS line and switches its termination accordingly. In LVD mode, it provides precise termination with 105Ω differential and 150Ω common mode impedance. If Single-Ended (SE) or High Voltage Differential (HVD) devices are detected, the device isolates its termination pins from the bus to prevent signal degradation.
| Operating Temperature Range | 0 to 70 °C |
|---|---|
| Thermal Shutdown Temperature | 150 °C |
| Low Power-down Capacitance | 3 pF |
| Termpower Voltage (LVD mode) | 2.7 to 5.5 V |
The device automatically switches termination modes by sensing the voltage on the DIFFSENS line to detect if the bus is SE, HVD, or LVD.
Three DS2121A terminators are required for a wide SCSI bus.
The DS2121A identifies the SE device and isolates its termination pins from the SCSI bus.