DS21T07 Fast Delivery |IC PHOENIX CO.,LIMITED

DS21T07 ,SCSI TerminatorFUNCTIONAL DESCRIPTIONThe DS21T07 consists of a bandgap reference, buffer amplifier, and nine termi ..
DS21T07E ,SCSI TerminatorFUNCTIONAL DESCRIPTIONThe DS21T07 consists of a bandgap reference, buffer amplifier, and nine termi ..
DS21T07S ,SCSI TerminatorFUNCTIONAL DESCRIPTIONThe DS21T07 consists of a bandgap reference, buffer amplifier, and nine termi ..
DS21T07S+ ,SCSI TerminatorFEATURES PIN ASSIGNMENT Fully compliant with SCSI–1, Fast SCSI andUltra SCSI1 16TERMPWR1 PD Backw ..
DS21T07S+T&R ,SCSI TerminatorBLOCK DIAGRAM Figure 12 of 7Downloaded from: http://www.ic-phoenix.com/stock/DS21T07TYPICAL SCSI BU ..
DS21T09 ,Plug and Play SCSI TerminatorFEATURES PIN ASSIGNMENT Fully compliant with SCSI-1, Fast SCSI andUltra SCSI PDI 1 28 GND2 27 R18R ..
E53NA50 ,NABSOLUTE MAXIMUM RATINGSSymbol Parameter Value UnitV Drain-source Voltage (V =0) 500 VDS GSV 500 VD ..

DS21T07
SCSI Terminator
FEATURESFully compliant with SCSI–1, Fast SCSI and
Ultra SCSIBackward compatible to the DS2107,
DS2107A, and DS21S07Provides active termination for nine signal
linesLaser–trimmed 110 ohms termination
resistors have 2% toleranceLow dropout voltage regulatorPower–down mode isolates termination
resistors from the busSCSI bus hot–plug compatibleFully supports actively negated SCSI signalsOnboard thermal shutdown circuitry16–pin plastic SOIC (DS21T07S) and 20–pin
plastic TSSOP (Thin Shrink Small Outline
Package) (DS21T07E)
PIN ASSIGNMENT
ACTUAL FOOTPRINT SIZE
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.
DS21T07
SCSI Terminator
www.dalsemi.com
VREF2
HS-GND
HS-GND
TERMPWR2
TERMPWR1
HS-GND
HS-GND
VREF1
GND
DS21T07E 20-pin TSSOP (173-mil)
VREF2
TERMPWR2
TERMPWR1
VREF1
GND
DS21T07S 16-pin SOIC (300-mil)
0.41”
0.41”
0.26”
0.27”
DS21T07SDS21T07E
DS21T07
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 VREF 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 50KΩ=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
DS21T07
TYPICAL SCSI BUS CONFIGURATION Figure 2
NOTES:
1. C1 = 4.7 μF tantalum
C2 = 2.2 μF tantalum or 4.7 μF aluminum
2. If the DS21T07 is to be embedded into a peripheral that will act as a target on a SCSI bus, it is that
recommended TERMPWR be derived from the SCSI cable, not generated locally. In this
configuration, if a power failure occurs in the peripheral, it will not affect the bus.
3. A high frequency bypass capacitor (0.1 μF recommended) can be added in parallel to C1 for
applications using fast rise/fall time drivers.
DS21T07DS21T07
DS21T07
PIN DESCRIPTION Table 1
DS21T16E
PIN
DS21T16S
PIN
SYMBOLDESCRIPTION1TERMPWR1Termination Power 1. Should be connected to the SCSI
TERMPWR line. Must be decoupled with either a 2.2
μF or 4.7 μF. See Figure 2.R1Signal Termination 1. 110 ohms termination.R2Signal Termination 2. 110 ohms termination.R3Signal Termination 3. 110 ohms termination.R4Signal Termination 4. 110 ohms termination.R5Signal Termination 5. 110 ohms termination.VREF1Reference Voltage 1. Must be externally connected
directly to the VREF2 pin. Must be decoupled with a 4.7
μF capacitor as shown in Figure 2.8GNDGround. Signal ground; 0.0V.9TERMPWR2Termination Power 2. Should be connected to the SCSI
TERMPWR line. Must be decoupled with either a 2.2
μF or 4.7 μF. See Figure 2.10R6Signal Termination 6. 110 ohms termination.11R7Signal Termination 7. 110 ohms termination.12R8Signal Termination 8. 110 ohms termination.13R9Signal Termination 9. 110 ohms termination.14NCNo Connect. Do not connect any signal to this pin.15VREF2Reference Voltage 2. Must be externally connected
directly to the VREF1 pin. Must be decoupled with a 4.7
μF capacitor as shown in Figure 2.16PDPower Down. When tied low, the DS21T07 enters a
power-down mode. Contains an internal 50K pullup.
Strap low to deactivate the DS21T07, leave open
circuited to activate the DS21T07.
2, 8,
12, 18
N/AHS-GNDHeat Sink Ground. Internally connected to the
mounting pad. Should be either grounded or electrically
isolated from other circuitry.
DS21T07
ABSOLUTE MAXIMUM RATINGS*
Voltage on Any Pin Relative to Ground-1.0V to +7.0V
Operating Temperature0°C to 70°C
Storage Temperature-55°C to +125°C
Soldering Temperature260°C for 10 secondsThis is a stress rating only and functional operation of the device at these or any other conditions
above those indicated in the operation sections of this specification is not implied. Exposure to
absolute maximum rating conditions for extended periods of time may affect reliability.
The Dallas Semiconductor DS21T07 is built to the highest quality standards and manufactured for long-
term reliability. All Dallas Semiconductor devices are made using the same quality materials and
manufacturing methods. However, the DS21T07 is not exposed to environmental stresses, such as burn-
in, that some industrial applications require. For specific reliability information on this product, please
contact the factory in Dallas at (972) 371-4448.
RECOMMENDED OPERATING CONDITIONS(0°C to 70°C)
PARAMETERSYMMINTYPMAXUNITSNOTES
TERMPWR VoltageVTP4.005.50V ActiveVPDA-0.3+0.8V InactiveVPDI2.0VTP + 0.3V
DC CHARACTERISTICS(0°C to 70°C)
PARAMETERSYMBOLMINTYPMAXUNITSNOTES
TERMPWR CurrentITP
ITP5
1, 3
1, 4
Power-Down CurrentIPD100150μA1, 2, 5
Termination ResistanceRTERM108110112ohms1, 2
Die Thermal ShutdownTSD150150°C1, 6
Power-Down
Termination Capacitance
CPD3.0pF1, 2, 5, 6
Input Leakage HighIIH-1.0μA1, 8
Input Leakage LowIIL1.0μA1, 7
REGULATOR CHARACTERISTICS(0°C to 70°C)
PARAMETERSYMBOLMINTYPMAXUNITSNOTES
Output VoltageVREF2.792.852.93V1, 2
Drop Out VoltageVDROP0.500.75V3, 6
Output CurrentIOUT25.2mA9
Line RegulationLIREG1.02.0%1, 4
Load RegulationLOREG1.33.0%1, 3
Current LimitILIM350mA1
Sink CurrentISINK200mA1
DS21T07
NOTES:
1. 4.00V < TERMPWR < 5.50V.
2. 0.0V < signal lines < 3.0V.
3. All signal lines = 0.0V.
4. All signal lines open.
5. PD = 0.0V.
6. Guaranteed by design; not production tested.
7. R1 through R9 only.
8. R1 through R9 and PD.
9. VSIGNAL = 0.2V.
DS21T07S SCSI TERMINATOR 16-PIN SOIC (300-mil)
PKG16-PIN
DIMMINMAX
A IN.
B IN.
C IN.
E IN.
F IN.
G IN.
0.050 BSC
1.27 BSC
H IN.
J IN.
K IN.
L IN.
phi0°8°

Partno	Mfg	Dc	Qty	Available	Descript
DS21T07	DALLAS	N/a	10	avai	SCSI Terminator