The DS2125 Ultra3 LVD/SE SCSI terminator is both a low-voltage differential (LVD) and single-ended (SE) terminator. The multimode operation enables the designer to implement LVD in current products while allowing the end user SE backward compatibility with legacy devices. If the device is connected in an LVD-only bus, the DS2125 uses LVD termination. If any SE devices are connected to the bus, the DS2125 uses SE termination, which is accomplished automatically inside the part by sensing the voltage on the SCSI bus DIFFSENS line. For the LVD termination, the DS2125 integrates two current sources with 15 precision resistor strings. For the SE termination, one regulator and 15 precision 110� resistors are used. Two DS2125 terminators are needed for a wide SCSI bus.
The DS2125 is an integrated circuit designed to provide both low-voltage differential (LVD) and single-ended (SE) termination for Ultra3 SCSI buses. It features automatic mode selection by sensing the DIFFSENS line, allowing it to support legacy SE devices while enabling current LVD products. The device integrates precision resistor strings and regulators to maintain accurate impedance in either mode.
| Supply Current (LVD Mode) | 20 µA typical |
|---|---|
| Supply Voltage Range (LVD) | 2.7V to 5.5V |
| Pin Count | 48 pins |
The device supports both low-voltage differential (LVD) and single-ended (SE) termination.
It automatically selects the appropriate mode by sensing the voltage on the DIFFSENS line.
A 4.7µF capacitor is required between the Vref pin and ground to maintain specified regulation.