Passive termination does no work to regulate power. Instead, it relies on the host adapter or device to supply TERMPWR voltage. Passive termination is the original termination method used for parallel SCSI. Passive terminators provide an impedance match that is close to the impedance of the cable to minimize possible signal reflections.
Passive termination is reliable for bus speeds up to 10 MHz. Passive termi-nators connect a 220-Ohm resistor to the TERMPWR line and 330-Ohm resistor to ground with an optimum impedance match of 132 Ohms. Passive termination is adequate for short distances (less than 1 meter) or for low speed SCSI devices such as CD-ROMs and scanners. Passive termination is not recommended if there are more than two peripheral devices on the bus.
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