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参数资料
| 型号： | DS2117MB |
| 厂商： | DALLAS SEMICONDUCTOR |
| 元件分类： | Bus Terminator |
| 英文描述： | 9-LINE 52 ohm SCSI BUS TERMINATOR, PDSO36 |
| 封装： | SSOP-36 |
| 文件页数： | 2/9页 |
| 文件大小： | 265K |
| 代理商： | DS2117MB |
DS2117M
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REFERENCE DOCUMENTS
Small Computer Systems Interface (SCSI-3) SCSI Parallel Interface (SPI)
Project: 0855-M, 1995
Small Computer Systems Interface (SCSI-3) SCSI Parallel Interface 2 (SPI-2) Project: 1142-M, 1998
Small Computer Systems Interface (SCSI-3) SCSI Parallel Interface 3 (SPI-3) Project: 1302-D, 1999
Small Computer Systems Interface (SCSI-3) SCSI Parallel Interface 4 (SPI-4) Project: 1365-D, xxxx
Available from:
American National Standards Institute (ANSI) Phone: (212) 642-4900
Global Engineering Documents 15 Inverness Way East; Englewood, CO 80112 Phone: (800) 854-7179
FUNCTIONAL DESCRIPTION
The DS2117 combines LVD and SE termination with DIFFSENSE sourcing and detection.
A bandgap reference is fed into two amplifiers, which creates a 1.25V reference voltage and a 2.85V
reference voltage. The control logic determines which of these references will be applied to the
termination resistors. If the SCSI bus is in LVD mode, then the 1.25V reference will be used. If the SCSI
bus is in SE mode, then the 2.85V reference will be used. That same control logic will switch in/out
parallel resistors to change the total termination resistance accordingly. Finally, in SE mode the Rp pins
will be switched to ground.
The DIFFSENSE circuitry decodes trinary logic. There will be one of three voltages on the SCSI control
line called DIFFSENS. Two comparators and a NAND gate determine if the voltage is below 0.6V, above
2.15V, or in between. That indicates the mode of the bus to be HVD, SE, or LVD, respectively.
The DS2117M’s DIFF_CAP pin monitors the DIFFSENS line to determine the proper operating mode of
the device; this mode is indicated by the SE/LVD/HVD outputs. The DIFFSENSE pin can also drive the
SCSI DIFFSENS line (when MSTR/SLV = 1) to determine the SCSI bus operating mode. The DS2117M
switches to the termination mode that is appropriate for the bus based on the value of the DIFFSENS
voltage. These modes are:
LVD mode LVD termination is provided by a precision laser trimmed resistor string with two current
sources. This configuration yields a 105
differential and 150 common mode impedance. A fail-safe
bias of 112 mV is maintained when no drivers are connected to the SCSI bus.
SE mode When the external driver for a given signal line turns off, the active terminator will pull that
signal line to 2.85 volts (quiescent state). When used with an active negation driver, the power amp can
sink 22 mA per line while keeping the voltage reference in regulation. The terminating resistors maintain
their 110
value.
HVD Isolation Mode The DS2117M identifies that there is an HVD (high voltage differential) device on
the SCSI bus and isolates the termination pins from the bus.
When ISO is pulled high, the termination pins are isolated from the SCSI bus, Vref is grounded, and the
bus mode indicators (SE/LVD/HVD) remain active. During thermal shutdown, the termination pins are
isolated from the SCSI bus, Vref is grounded, and the bus mode indicators (SE/LVD/HVD) remain
active. The DIFFSENSE driver is shut down during either of these two events.
相关PDF资料 |
PDF描述 |
|---|---|
| DS2118M | 9-LINE SCSI BUS TERMINATOR, PDSO36 |
| DS2119ME | 9-LINE 52 ohm SCSI BUS TERMINATOR, PDSO28 |
| DS2154LN | DATACOM, FRAMER, PQFP100 |
| DS2155GN | DATACOM, FRAMER, PBGA100 |
| DS2155L | DATACOM, FRAMER, PQFP100 |
相关代理商/技术参数 |
参数描述 |
|---|---|
| DS2117MB/T&R | 制造商:Maxim Integrated Products 功能描述:IC TERM SCSI LVD/SE ULT-3 36SSOP |
| DS2117MB/T&R | 功能描述:SCSI 接口集成电路 RoHS:否 制造商:Texas Instruments 工作电源电压:2.7 V to 5.25 V 电源电流:13 mA 最大工作温度:+ 70 C 最小工作温度:0 C 安装风格:SMD/SMT 封装 / 箱体:SSOP-36 封装:Tube |
| DS2117MB/T&R/ | 功能描述:SCSI 接口集成电路 RoHS:否 制造商:Texas Instruments 工作电源电压:2.7 V to 5.25 V 电源电流:13 mA 最大工作温度:+ 70 C 最小工作温度:0 C 安装风格:SMD/SMT 封装 / 箱体:SSOP-36 封装:Tube |
| DS2117MX/T&R | 制造商:Maxim Integrated Products 功能描述:IC TERM SCSI LVD/SE ULT-3 FCHIP |
| DS2117MX/T&R | 功能描述:IC TERM SCSI LVD/SE ULT-3 FCHIP RoHS:否 类别:集成电路 (IC) >> 接口 - 信号终端器 系列:- 产品培训模块:Lead (SnPb) Finish for COTS Obsolescence Mitigation Program 标准包装:50 系列:- 类型:SCSI，SE 端子数:9 电源电压:4 V ~ 5.25 V 工作温度:0°C ~ 70°C 安装类型:表面贴装 封装/外壳:16-SOIC（0.154"，3.90mm 宽） 供应商设备封装:16-SOIC 包装:管件 |
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