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参数资料
| 型号： | ISL31485EIBZ-T7A |
| 厂商： | Intersil |
| 文件页数： | 7/24页 |
| 文件大小： | 0K |
| 描述： | IC TXRX RS485 FAULT PROT 8SOIC |
| 标准包装： | 1 |
| 类型： | 收发器 |
| 驱动器/接收器数： | 1/1 |
| 规程： | RS422，RS485 |
| 电源电压： | 4.5 V ~ 5.5 V |
| 安装类型： | 表面贴装 |
| 封装/外壳： | 8-SOIC（0.154"，3.90mm 宽） |
| 供应商设备封装： | 8-SOICN |
| 包装： | 标准包装 |
| 其它名称： | ISL31485EIBZ-T7ADKR |
ISL31480E, ISL31483E, ISL31485E, ISL31486E
15
FN7638.2
and Z being inverting. With the invert pin high, the corresponding
bus pins reverse their polarity, so B and Z are now noninverting
and A and Y become inverting.
Intersil’s unique cable invert function is superior to that found on
competing devices because the Rx full failsafe function is
maintained even when the Rx polarity is reversed. Competitor
devices implement the Rx invert function simply by inverting the
Rx output. This means that with the Rx inputs floating or shorted
together, the Rx appropriately delivers a logic 1 in normal
polarity, but outputs a logic low when the IC is operated in the
inverted mode. Intersil’s innovative Rx design guarantees that
with the Rx inputs floating, or shorted together (VID =0V), the Rx
output remains high regardless of the state of the invert pins.
The full duplex ISL31483E includes two invert pins that allow for
separate control of the Rx and Tx polarities. If only the Rx cable is
miswired, then only the RINV pin need be driven to a logic 1. If
the Tx cable is miswired, then DINV must be connected to a logic
high. The two half duplex versions have only one logic pin (INV)
that, when high, switches the polarity of both the Tx and the Rx
blocks.
Logic Supply (VL Pin)
Note: Power up VCC before powering up the VL supply, and keep
VL ≤ VCC.
The ISL31480E and ISL31486E include a VL pin that powers the logic
inputs (Tx input and control pins) and the Rx output. These pins
interface with “logic” devices such as UARTs, ASICs, and controllers,
and today many of these devices use power supplies significantly lower
than 5V. Thus, a 5V output level from this transceiver IC might seriously
overdrive and damage the logic device input (see Figure 9). Similarly,
the logic device’s low VOH might not exceed the VIH of a 5V powered
transceiver input. Connecting the VL pin to the power supply of the logic
VL voltage, and reduces the Tx and control input switching points to
values compatible with the logic device output levels. Tailoring the logic
pin input switching points and output levels to the supply voltage of the
UART, ASIC, or controller eliminates the need for a level
shifter/translator between the two ICs.
VL can be anywhere from VCC down to 1.62V, and the
transceivers easily operate at the 1Mbps data rate over this
range as long as the VCM doesn’t exceed ±15V. Table 2 indicates
typical VIH and VIL values for various VL voltages so the user can
ascertain whether or not a particular VL voltage meets his/her
needs.
The VL supply current (IL) is typically less than 6A. All of the DC
VL current is due to current through the DE input internal pull-up
resistor when the pin is driven to the low input state.
Transceiver logic inputs that are externally tied high in an application
should use the VL supply for the high voltage level to minimize input
currents. Except for DI, all logic inputs have 800k pull-up (DE) or pull-
down (all other pins) resistors, so connecting an input to the lower
voltage VL supply minimizes current. The DE pull-up internally connects
to VL, so connecting the DE pin to VCC induces an input current of (VCC -
VL)/800k.
High VOD Improves Noise Immunity and
Flexibility
The ISL3148xE driver design delivers larger differential output
voltages (VOD) than the RS-485 standard requires, or than most
RS-485 transmitters can deliver. The typical ±2.5V VOD provides
more noise immunity than networks built using many other
transceivers.
Another advantage of the large VOD is the ability to drive more
than two bus terminations, which allows for utilizing the
ISL3148xE in “star” and other multi-terminated, nonstandard
network topologies.
and includes load lines for four (30) and six (20) 120
terminations. The figure shows that the driver typically delivers
±1.3V into six terminations, and the “Electrical Specification”
table guarantees a VOD of ±0.8V at 21 over the full temperature
range. The RS-485 standard requires a minimum 1.5V VOD into
two terminations, but the ISL3148xE deliver RS-485 voltage
levels with 2x to 3x the number of terminations.
Hot Plug Function
When a piece of equipment powers up, there is a period of time
where the processor or ASIC driving the RS-485 control lines (DE,
RE) is unable to ensure that the RS-485 Tx and Rx outputs are
TABLE 2. VIH AND VIL vs. VL FOR VCC = 5V
VL (V)
VIH (V)
VIL (V)
1.6
1.0
0.6
1.8
1.1
0.7
2.3
1.3
0.9
2.7
1.4
1.1
3.3
1.6
1.3
FIGURE 9. USING VL PIN TO ADJUST LOGIC LEVELS
GND
RXD
TXD
VCC = +1.8V
UART/PROCESSOR
GND
RO
DI
VCC = +5V
ISL31483E
VOH ≈ 1.8V
VOH = 5V
VIH ≥ 2V
ESD
DIODE
GND
RXD
TXD
VCC = +1.8V
UART/PROCESSOR
GND
RO
DI
VCC = +5V
ISL31480E
VOH ≈ 1.8V
VOH = 1.8V
VIH = 1.1V
ESD
DIODE
VL
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相关代理商/技术参数 |
参数描述 |
|---|---|
| ISL31486E | 制造商:INTERSIL 制造商全称:Intersil Corporation 功能描述:Fault Protected, Extended CMR, RS-485/RS-422 Transceivers with Cable Invert |
| ISL31486EIBZ | 制造商:INTERSIL 制造商全称:Intersil Corporation 功能描述:Fault Protected, Extended CMR, RS-485/RS-422 Transceivers with Cable Invert |
| ISL31486EIRTZ | 制造商:INTERSIL 制造商全称:Intersil Corporation 功能描述:Fault Protected, Extended CMR, RS-485/RS-422 Transceivers with Cable Invert |
| ISL31486EIUZ | 制造商:INTERSIL 制造商全称:Intersil Corporation 功能描述:Fault Protected, Extended CMR, RS-485/RS-422 Transceivers with Cable Invert |
| ISL31490E | 制造商:INTERSIL 制造商全称:Intersil Corporation 功能描述:?±60V Fault Protected, 5V, RS-485/RS-422 Transceivers with ?±25V Common Mode Range |
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