DS21T07 Datasheet, PDF (1/7 Pages) Dallas Semiconductor – SCSI Terminator

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DS21T07
SCSI Terminator
FEATURES
Fully compliant with SCSI–1, Fast SCSI and
Ultra SCSI
Backward compatible to the DS2107,
DS2107A, and DS21S07
Provides active termination for nine signal
lines
Laser–trimmed 110 ohms termination
resistors have 2% tolerance
Low dropout voltage regulator
Power–down mode isolates termination
resistors from the bus
SCSI bus hot–plug compatible
Fully supports actively negated SCSI signals
Onboard thermal shutdown circuitry
16–pin plastic SOIC (DS21T07S) and 20–pin
plastic TSSOP (Thin Shrink Small Outline
Package) (DS21T07E)
PIN ASSIGNMENT
TERMPWR1 1
R1 2
R2 3
R3 4
R4 5
R5 6
VREF1 7
GND 8
16 PD
15 VREF2
14 NC
13 R9
12 R8
11 R7
10 R6
9 TERMPWR2
DS21T07S 16-pin SOIC (300-mil)
TERMPWR1 1
HS-GND 2
R1 3
R2 4
R3 5
R4 6
R5 7
HS-GND 8
VREF1 9
GND 10
20 PD
19 VREF2
18 HS-GND
17 NC
16 R9
15 R8
14 R7
13 R6
12 HS-GND
11 TERMPWR2
DS21T07E 20-pin TSSOP (173-mil)
ACTUAL FOOTPRINT SIZE
0.41”
0.26”
0.41”
0.27”
DS21T07S
DS21T07E
DESCRIPTION
Fast SCSI and Ultra SCSI require the use of active terminations at both ends of every cable segment in a
SCSI system with single-ended drivers and receivers. The DS21T07 SCSI Terminator, which is fully
compliant with these standards, enables the designer to gain the benefits of active termination: greater
immunity to voltage drops on the TERMPWR (TERMination PoWeR) line, enhanced high-level noise
immunity, intrinsic TERMPWR decoupling, and very low quiescent current consumption. The DS21T07
integrates a regulator and nine precise switched 110 ohms termination resistors into a monolithic IC. The
DS21T07 can be electrically isolated from the SCSI bus without physical removal from the SCSI device.
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