The DS2118M is a Ultra2 LVD/SE SCSI terminator from Dalsemi. It supports both LVD and SE modes and can be used on LVD and SE buses. It has auto-selection of LVD or SE termination and has a 5% tolerance on SE and LVD termination resistance. Its power down capacitance is low and it is hot plug compatible.
The DS2118M is an Ultra2 LVD/SE SCSI terminator designed to provide multimode low voltage VREF differential/single-ended termination for 9 signal line pairs. It features auto-selection of LVD or SE termination based on the voltage on the SCSI bus DIFFSENS line, ensuring compatibility with both current LVD products and legacy SE devices. The device integrates two regulated supplies with nine precision resistor strings for LVD termination and one regulator with nine precision 110-ohm resistors for SE termination.
The document provides a comprehensive functional description, including the DIFFSENSE circuitry that decodes trinary logic to determine bus mode (HVD, SE, or LVD). It details the recommended operating conditions, single-ended and low voltage differential characteristics, DC characteristics, and regulator characteristics. Additionally, it includes a block diagram, a typical SCSI bus configuration, a pin description table, and mechanical package dimensions for the 36-pin SSOP package.
| Termination Resistance (LVD) | 105 Ohm differential |
|---|---|
| Output Capacitance | 3 pF |
| Operating Temperature | 0 to 70 °C |
| SE Voltage Reference | 2.85 volts |
| DIFFSENSE Driver Current | 5 mA |
| Package Type | 36-Pin SSOP |
The device automatically selects the termination mode by sensing the voltage on the SCSI bus DIFFSENS line.
Three DS2118M terminators are required for a Wide SCSI bus.
A 4.7 uF capacitor is required between the Vref pin and ground of each DS2118M.