DS2105 Fast Delivery |IC PHOENIX CO.,LIMITED

DS2105 ,SCSI TerminatorFUNCTIONAL DESCRIPTIONThe DS2105 consists of a bandgap reference, buffernal 50KW pull–up resistor. ..
DS2108S ,Differential SCSI Switchable TerminatorFUNCTIONAL DESCRIPTIONThe DS2108 consists of power-down circuitry, eighteen 330-ohm and nine 150-oh ..
DS2108S/T&R ,Differential SCSI Switchable TerminatorFEATURES PIN ASSIGNMENT Fully compliant with SCSI, SCSI-2 and SCSI-3 standards1 24TPWR PD Conform ..
DS2109 ,Plug and Play SCSI TerminatorFUNCTIONAL DESCRIPTIONSCSI–2 (X3.131–1994) The DS2109 is designed to be a single chip terminationSC ..
DS2117M ,Ultra2 LVD/SE SCSI TerminatorFUNCTIONAL DESCRIPTIONThe DS2117 combines LVD and SE termination with DIFFSENSE sourcing and detect ..
DS2118M ,Ultra3 LVD/SE SCSI TerminatorFEATURES PIN CONFIGURATION Fully Compliant with SCSI SPI-2, SPI-3, SPI-4, Ultra160, and Ultra32 ..

DS2105
SCSI Terminator
DS2105
SCSI Terminator
DS2105
022698 1/7
FEATURESFully compliant with SCSI–1, Fast SCSI and Ultra
SCSIFunctionally compatible to the DS21S07A, targeted
for high volume applicationsProvides active termination for nine signal linesLaser–trimmed 110 ohm termination resistors have
5% toleranceLow dropout voltagePower–down mode isolates termination resistors
from the busFully supports actively negated SCSI signalsOnboard thermal shutdown circuitry16–pin plastic SOIC (DS2105)
PIN ASSIGNMENT9
DS2105Z 16–PIN SOIC (150 MIL)
TERMPWR1
VREF1
GND
VREF2
TERMPWR29
DS2105S 16–PIN SOIC (300 MIL)
TERMPWR1
VREF1
GND
VREF2
TERMPWR2
DESCRIPTION
Fast SCSI and Ultra SCSI require the use of active ter-
minations at both ends of every cable segment in a
SCSI system with single–ended drivers and receivers.
The DS2105 SCSI Terminator, which is fully compliant
with these standards, enables the designer to gain the
benefits of active termination: greater immunity to volt-
age drops on the TERMPWR (TERMination PoWeR)
line, enhanced high–level noise immunity, intrinsic
TERMPWR decoupling, and very low quiescent current
consumption. The DS2105, which integrates a regula-
tor and nine precise switched 110 ohm termination re-
sistors into a monolithic IC, is a functionally compatible
version of the DS21S07A. With relaxed output current
and termination tolerances, the DS2105 is intended for
high volume applications which require active termina-
tion but not the high performance of the DS21S07A.
The DS2105 is offered in both 300 mil and 150 mil SOIC
packages.
DS2105
022698 2/7
FUNCTIONAL DESCRIPTION
The DS2105 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 pro-
duces 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 200 mA, and VREF will
move less than 60 mV. When all lines settle in the quies-
cent state, the regulator will consume about 5 mA.
When the DS2105 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
DS2105 from the signal lines and effectively remove it
from the circuit. The power–down pin (PD) has an inter-
nal 50KW pull–up resistor. To place the DS2105 into an
active state, the PD pin should be left open circuited.
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 DS2105 requires
a 4.7 mF capacitor connected between the VREF pins
and ground. Figure 2 details a typical SCSI bus configu-
ration. In an 8–bit wide SCSI bus arrangement (“A”
Cable), two DS2105’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 (“P”
Cable), three DS2105’s would be needed at each end of
the SCSI cable in order to terminate the 27 active signal
lines.
DS2105 BLOCK DIAGRAM Figure 1
GND
TERMPWR1
TERMPWR2
POWER
DOWN
CIRCUITRY50K ohm
BANDGAP
REFERENCE
110 ohms
VREF1
VREF2
110 ohms
110 ohms
110 ohms
110 ohms
110 ohms
110 ohms
110 ohms
110 ohms
DS2105
022698 3/7
TYPICAL SCSI BUS CONFIGURATION Figure 2
Termination Power Line
SCSI
BUS
TRANSCEIVER
SCSI
BUS
TRANSCEIVER
SCSI
BUS
TRANSCEIVER
SCSI
BUS
TRANSCEIVER
DS2105
TERMPWR1
TERMPWR2
VREF1
VREF2
GNDR2R9
DS2105
TERMPWR1
TERMPWR2
VREF1
VREF2
GNDR9
SCSI
CABLE+C1+
NOTES:C1 = 4.7 mF tantalum
C2 = 2.2 mF tantalum or 4.7 mF aluminumIf the DS2105 is to be embedded into a peripheral that will act as a target on a SCSI bus, it is recommended that
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.A high frequency bypass capacitor (0.1 mF recommended) can be added in parallel to C1 for applications using
fast rise/fall time drivers.
DS2105
022698 4/7
PIN DESCRIPTION Table 1
DS2105S
PIN
DS2105Z
PIN
SYMBOLDESCRIPTION1TERMPWR1Termination Power 1. Should be connected to the SCSI
TERMPWR line. Must be decoupled with either a 2.2 mF or 4.7 mF.
See Figure 2.2R1Signal Termination 1. 110 ohm termination.3R2Signal Termination 2. 110 ohm termination.4R3Signal Termination 3. 110 ohm termination.5R4Signal Termination 4. 110 ohm termination.6R5Signal Termination 5. 110 ohm termination.7VREF1Reference Voltage 1. Must be externally connected directly to
the VREF2 pin. Must be decoupled with a 4.7 mF 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 mF or 4.7 mF.
See Figure 2.11R6Signal Termination 6. 110 ohm termination.12R7Signal Termination 7. 110 ohm termination.13R8Signal Termination 8. 110 ohm termination.14R9Signal Termination 9. 110 ohm termination.15VREF2Reference Voltage 2. Must be externally connected directly to
the VREF1 pin. Must be decoupled with a 4.7 mF capacitor as
shown in Figure 2.16PDPower Down. When tied low, the DS2105 enters a power–down
mode. Contains an internal 50K pull–up. Strap low to deactivate
the DS2105, leave open circuited to activate the DS2105.10NCNo Connect. Do not connect any signal to this pin.
DS2105
022698 5/7
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.
RECOMMENDED OPERATING CONDITIONS(0°C to 70°C)
PARAMETERSYMBOLMINTYPMAXUNITSNOTES
TERMPWR VoltageVTP4.005.25V
PD ActiveVPDA–0.3+0.8V
PD InactiveVPDI2.0VTP +0.3V
DC CHARACTERISTICS(0°C to 70°C)
PARAMETERSYMBOLMINTYPMAXUNITSNOTES
TERMPWR CurrentITP
ITP5
1, 3
1, 4
Power Down CurrentIPD500mA1, 2, 5
Termination ResistanceRTERM110118ohm1, 2
Die Thermal ShutdownTSD150°C1
Power Down Termination
Capacitance
CPD3.05.0pF1, 2, 5, 6
Input Leakage HighIIH–1.0mA1, 8
Input Leakage LowIIL1.0mA1, 7
REGULATOR CHARACTERISTICS(0°C to 70°C)
PARAMETERSYMBOLMINTYPMAXUNITSNOTES
Output VoltageVREF2.72.853.0V1, 2
Drop Out VoltageVDROP0.751.0V3, 6
Output CurrentIOUT24.0mA9
Line RegulationLIREG1.02.0%1, 4
Load RegulationLOREG1.33.0%1, 2
Current LimitILIM350mA1
Sink CurrentISINK200mA1
NOTES:4.00V < TERMPWR < 5.25V.0.0V < signal lines < 3.0V.All signal lines = 0.0V.All signal lines open.PD = 0.0V.
DS2105
022698 6/7Guaranteed by design; not production tested.R1 through R9 only.R1 through R9 and PD.VSIGNAL=0.2V.
DS2105Z SCSI TERMINATOR 16–PIN SOIC (150 MIL)
PKG16–PIN
DIMMINMAX
A IN.
A1 IN.
A2 IN.
b IN.
C IN
D IN.
e IN.
0.050 BSC
1.27 BSC
E1 IN.
H IN.
L IN.
0.890°8°

Partno	Mfg	Dc	Qty	Available	Descript
DS2105	DALLAS	N/a	40	avai	SCSI Terminator