DS21T09S Dallas Semiconducotr, DS21T09S Datasheet - Page 3

• Manufacturer Part Number: DS21T09S
• Description: Plug and Play SCSI Terminator
• Manufacturer: Dallas Semiconducotr

The DS21T09 consists of three major functional blocks, Figure 2:
When the Bus Ground Sensing Circuitry or Bus Current Sensing Circuitry determines that the SCSI bus
is properly terminated without the DS21T09, the power-down buffer isolates the resistors from the SCSI
bus and disables the power amp, thereby placing the DS21T09 in a low power mode (the bus sensing
circuitry always stays active). The
DS21T07 SCSI terminator for Wide SCSI configurations, Figure 8.
DS21T09 BLOCK DIAGRAM Figure 2
Voltage reference, terminating resistors, and isolation switches
Bus current sensing circuitry
Bus ground sensing circuitry
PDO
(Power-Down Output) pin can be connected to the pin of a
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