參數(shù)資料
型號(hào): DS21T07
英文描述: SCSI Terminator
中文描述: SCSI端接器
文件頁(yè)數(shù): 2/7頁(yè)
文件大?。?/td> 101K
代理商: DS21T07
DS21T07
2 of 7
FUNCTIONAL DESCRIPTION
The DS21T07 consists of a bandgap reference, buffer amplifier, and nine termination resistors (Figure 1).
The bandgap reference circuit produces a precise 2.55V level which is fed to a buffer amplifier. The
buffer produces a 2.85V level and is capable of sourcing at least 24 mA into each of the termination
resistors when the signal line is low (active). When the driver for a given signal line turns off, the
terminator will pull the signal line to 2.85V (quiescent state). To handle actively negated SCSI signals,
the buffer can sink at least 200 mA, and V
REF
will move less than 60 mV. When all lines settle in the
quiescent state, the regulator will consume about 5 mA. When the DS21T07 is put into power-down
mode by bringing
PD
low, the power-down circuitry will turn off the transistors on each signal line. This
will isolate the DS21T07 from the signal lines and effectively remove it from the circuit. The power-
down pin (
PD
) has an internal 50K
=
pullup resistor. To place the DS21T07 into an active state, the
PD
pin should be left open circuited. When installed on disk drives or RAID system components, the
DS21T07 will not affect the SCSI bus during a hot plug operation.
To ensure proper operation, both the TERMPWR1 and TERMPWR2 pins must be connected to the SCSI
bus TERMPWR line and both the VREF1 and VREF2 pins must be tied together externally. Each
DS21T07 requires a 4.7 μF capacitor connected between the VREF pins and ground. Figure 2 details a
typical SCSI bus configuration. In an 8-bit wide SCSI bus arrangement, two DS21T07’s would be needed
at each end of the SCSI cable in order to terminate the 18 active signal lines. In a 16-bit wide SCSI bus
arrangement, three DS21T07’s would be needed at each end of the SCSI cable in order to terminate the
27 active signal lines.
DS21T16 BLOCK DIAGRAM
Figure 1
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相關(guān)代理商/技術(shù)參數(shù)
參數(shù)描述
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DS21T07E/T&R/C16 制造商:Rochester Electronics LLC 功能描述: 制造商:Maxim Integrated Products 功能描述:
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