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參數(shù)資料
| 型號(hào)： | DS2127+T&R |
| 廠(chǎng)商： | Maxim Integrated Products |
| 文件頁(yè)數(shù)： | 5/6頁(yè) |
| 文件大?。?/td> | 0K |
| 描述： | IC TERM SCSI LVD/SE 48-LQFP |
| 標(biāo)準(zhǔn)包裝： | 2,000 |
| 類(lèi)型： | SCSI，LVD，SE |
| 端子數(shù)： | 14 |
| 電源電壓： | 2.7 V ~ 5.5 V |
| 工作溫度： | 0°C ~ 70°C |
| 安裝類(lèi)型： | 表面貼裝 |
| 封裝/外殼： | 48-LQFP |
| 供應(yīng)商設(shè)備封裝： | 48-LQFP（7x7） |
| 包裝： | 帶卷 (TR) |
Detailed Description
The DS2127 provides dual-mode active terminators
with auto-switching SE and LVD termination for 14 SCSI
lines. The DIFFSENSE signal performs mode detection
and selection.
In LVD mode, the termination configuration is a y-type
terminator with a 105
differential resistance and a
150
common-mode resistance. The termination resis-
tor is biased with two current sources and the common-
mode node is connected to a 1.25V voltage regulator.
A fail-safe bias of 112mV is maintained when no drivers
are connected to the SCSI bus.
In SE mode, each negative signal input pin is connect-
ed to 2.85V through a 110
resistor.
In HVD mode, the termination resistors are isolated
from the SCSI bus and the resistor pins are left floating.
The voltage regulator is powered down and the VREF
pin is in a high-impedance state.
The DIFF_CAP pin is connected to the SCSI DIFFSENSE
line and monitors the voltage to determine the proper
operating mode of the device. Any DIFFSENSE voltage
below 0.5V indicates single ended; any DIFFSENSE volt-
age between 0.7V and 1.9V is LVD, and above 2.4V is
an HVD SCSI. On power-up, the DS2127 assumes SE
mode. If the voltage on the DIFF_CAP is between 0.7V
and 1.9V, the device waits tDELAY before entering the
LVD mode. The delay is the same when changing
modes. A new mode change can start at any time after a
previous mode change has been detected.
Typically, four DS2127s are used in a SCSI bus seg-
ment. On two chips, the DIFF_CAP inputs at each end
of the bus should be connected together. There should
be a 50Hz noise filter implemented on DIFF_CAP at
each end of the bus, as close as possible to the
DIFF_CAP pins. This filter consists of a 20k
resistor
between the DIFFSENS and DIFF_CAP pins, and a
0.1F capacitor from DIFF_CAP to GND. See Figure 2
for the typical operating circuit.
When ISO is connected to TPWR, the termination pins
are isolated from the SCSI bus and VREF becomes
inactive, and the device is in a low-power state. During
thermal shutdown, the termination pins are isolated
from the SCSI bus and VREF becomes high impedance.
The DIFFSENS driver is shut down during either of
these two events. LVD and SE signals indicate whether
the SCSI bus segment is in LVD or SE mode.
Chip Information
TRANSISTOR COUNT: 8114 CMOS and 87 Bipolar
PROCESS: BiCMOS
SUBSTRATE CONNECTED TO GROUND
Thermal Information
Thermal Resistance (junction-to-ambient):
θJA = +29°C/W
Thermal Resistance (junction-to-case):
θJC = +10°C/W
DS2127
Ultra3 LVD/SE SCSI 14-Line Terminator
_____________________________________________________________________
5
TPWR
ISO
TPWR
ISO
DIFF_CAP
DIFFSENS
4.7
F
0.1
F
4.7
F
2.2
F
2.2
F
2.2
F
2.2
F
0.1
F
DIFFSENS
20k
20k
VREF
DIFFSENS
ISO
GND
TPWR
ISO
GND
TPWR
DIFFSENS
DIFF_CAP
4.7
F
4.7
F
DATA LINES (8) + PARITY
DATA LINES (4) + PARITY
CONTROL LINES (9)
DATA LINES (4)
GND
Figure 2. Typical Operating Circuit
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相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| DS2129 | 制造商:DALLAS 制造商全稱(chēng):Dallas Semiconductor 功能描述:LVD SCSI 27-Line Regulator |
| DS2129S | 功能描述:SCSI 接口集成電路 RoHS:否 制造商:Texas Instruments 工作電源電壓:2.7 V to 5.25 V 電源電流:13 mA 最大工作溫度:+ 70 C 最小工作溫度:0 C 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:SSOP-36 封裝:Tube |
| DS2129S/R | 制造商:DALLAS 制造商全稱(chēng):Dallas Semiconductor 功能描述:LVD SCSI 27-Line Regulator |
| DS2129S/T | 制造商:DALLAS 制造商全稱(chēng):Dallas Semiconductor 功能描述:LVD SCSI 27-Line Regulator |
| DS2129S/T&R | 功能描述:SCSI 接口集成電路 RoHS:否 制造商:Texas Instruments 工作電源電壓:2.7 V to 5.25 V 電源電流:13 mA 最大工作溫度:+ 70 C 最小工作溫度:0 C 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:SSOP-36 封裝:Tube |
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