DS2109 is a Plug and Play SCSI terminator that is fully compliant with SCSI-1, Fast SCSI, and Ultra SCSI. It provides active termination for 18 signal lines with 2% tolerance on termination resistors and voltage regulator. It also features bus termination sensing and low power down capacitance. The DS2109 integrates a low drop-out regulator, 18 precise switched 110 ohm termination resistors, and bus termination sensors.
The DS2109 is an integrated circuit designed as a one-chip Plug and Play (PnP) SCSI termination solution. It integrates a low drop-out regulator, 18 precise switched 110 ohm termination resistors, and bus termination sensors into a 28-pin SOIC package.
The device supports two automatic methods for disconnecting from the SCSI bus: Bus Ground Sensing and Bus Current Sensing. When an external device is connected or the bus is properly terminated without the DS2109, it isolates its resistors to maintain proper system termination while entering a low power mode.
| Output Voltage (VREF) | 2.79 to 2.91 V |
|---|---|
| Power Down Current | 1 to 2 mA |
The power down capacitance of the terminating resistors is low, with a specific value of 3 pF.
It uses either onboard current sensing circuitry or onboard ground detect circuitry to automatically switch off if an external device is connected.