Datasheet Linear Technology LTC1535ISW#PBF — 数据表
| 制造商 | Linear Technology |
| 系列 | LTC1535 |
| 零件号 | LTC1535ISW#PBF |
隔离式RS485收发器
数据表
LTC1535
Isolated RS485 Transceiver
Features Description UL Rated Isolated RS485: 2500VRMS
UL Recognized
File #E151738
n Eliminates Ground Loops
n 250kBd Maximum Data Rate
n Self-Powered with 420kHz Converter
n Half-or Full-Duplex
n Fail-Safe Output High for Open or
Shorted Receiver Inputs
n Short-Circuit Current Limit
n Slow Slew Rate Control
n 68kО© Input Impedance Allows Up to 128 Nodes
n Thermal Shutdow 8kV ESD Protection On Driver Outputs and
Receiver Inputs
n Available in 28-Lead SW Package The LTCВ®1535 is an isolated RS485 full-duplex differential
line transceiver. Isolated RS485 is ideal for systems where
the ground loop is broken to allow for much larger common mode voltage ranges. An internal capacitive isolation barrier provides 2500VRMS of isolation between the
line transceiver and the logic level interface. The powered
side contains a 420kHz push-pull converter to power the
isolated RS485 transceiver. Internal full-duplex communication occurs through the capacitive isolation barrier.
The transceiver meets RS485 and RS422 requirements. n В® Applications n n Isolated RS485 Receiver/Driver …
设计须知
- Isolated RS485 Transceiver Breaks Ground Loops &mdash DN228PDF, 992 Kb, 档案已发布: Apr 2, 2001从文件中提取
Isolated RS485 Transceiver Breaks Ground Loops – Design Note 228
Mitchell Lee Previously, isolation was achieved by using at least three
optoisolators and a separate isolated power supply. The
LTC1535 replaces not only the optoisolators, but also the
power supply, as it includes an on-chip DC/DC converter.
Other features include selectable driver slew rate to reduce
EMI and susceptibility to reflections, full-duplex pinout
and fail-safe detection of open and shorted lines.
The LTC1535 consists of two separate dice assembled on
a proprietary, isolated lead frame. The lead frame includes
integral coupling capacitors that bridge the isolation barrier
and exhibit 2,500VRMS guaranteed standoff. Data communication takes place via the coupling capacitors, while
an on-chip, 400kHz push-pull converter sends power to the
isolated side through a small transformer. Total common
mode capacitance across the barrier amounts to less than
20pF, with the transformer accounting for about 16pF of
the total. Figure 1 shows the complete circuit for a fully
isolated RS485 port.
Internally, the two halves of the LTC1535 communicate
in a ping-pong fashion, first sending transmit data to the
isolated side and then sending receive data back to the
nonisolated side. The sampling nature of the internal communications link means that some jitter is introduced into
the data; this limits the useful baud rate to approximately …
文章
- Isolated RS485 Transceiver Breaks Ground Loops &mdash LT JournalPDF, 308 Kb, 档案已发布: Nov 1, 1999从文件中提取
DESIGN IDEAS Isolated RS485 Transceiver
Breaks Ground Loops Linear Technology Magazine November 1999 For example, if the twisted pair is
accidentally miswired or faults to 117V
at some remote location, the floating
section of each LTC1535 and its associated circuitry will also carry 117V.
An unwary user or installer could
then come in contact with what is
assumed to be a safe, low voltage
circuit. Figure 6 shows how to detect
and warn the user that a fault condition exists on the twisted pair or its
shield. A small (3.2mm) glow lamp is
connected between GND2 (the
LTC1535’s floating ground) and the
equipment’s safety “earth” ground. If
a potential of more than 75VAC is
present on the twisted pair or shield,
B1 will light, indicating a wiring fault.
Resistors R3 and R4 are used to ballast the current in B1. Two resistors
are necessary because each resistor
can only stand off 200V, as well as for
reasons of power dissipation. As
shown, the circuit can withstand a
direct fault to a 440V, 3-phase system. …
模型线
- LTC1535CSW#PBF LTC1535CSW#TRPBF LTC1535ISW#PBF LTC1535ISW#TRPBF
制造商分类
- Interface > RS485/RS422 Transceivers
其他名称:
LTC1535ISWPBF, LTC1535ISW PBF