These Intersil RS-485 /RS-422 devices are ESD protected, BiCMOS 5V power supply, single transceiver, and meet the RS-485 and RS-422 balanced communication standards. Each driver output/receiver input is protected from ±15kV ESD strikes without latch-up. Unlike competing devices, this Intersil series is specified for a 10% tolerance supply (4.5V to 5.5V). The ISL8483E employs a slew rate limited driver that reduces EMI and minimizes reflections caused by improper termination of power transmission lines, or multi-drop and multi-drop applications. By using the ISL8485E has a higher slew rate. Both devices provide a "single-unit load" to the RS-485 bus, which allows up to 32 transceivers on the network. The receiver (Rx) input has a "fail-on-open" design if the Rx input is floating. The driver (Tx) outputs are short-circuit protected, even for voltages exceeding the supply voltage. Also, an on-chip thermal shutdown circuit disables the transmit output to prevent damage if the power dissipation is excessive. These half-duplex configurations combine Rx input and Tx output allowing the transceiver to disable the Rx and Tx functions in 8 leader packets.

feature

RS-485 input/output pins are ESD protected. 5kV High Voltage Motor - Class 3 ESD level on all other pins. >7kV high voltage motor

10% tolerance supply specified

High data rate version (ISL8485E). up to 5Mbps

Transition rate limited version transfer with no error data (ISL8483E). up to 250kbps

Single unit load allows up to 32 devices on the bus

1nA Low Current Shutdown Mode (ISL8483E)

Low Quiescent Current: -160µA (ISL8483E) - 340µA (ISL8485E) -7V to +12V Common Mode Input Voltage Range Three-State Rx and Tx Outputs 30ns Propagation Delay, 5ns Slope (ISL8485E) Operates from a Single +5V Supply (10% Tolerance) Driver Current Limit and Thermal Shutdown Overload Protection

application

factory automation

safety net

Building Environment Control System

Industrial/Process Control Networks

Level translator (eg RS-232 to RS-422) RS-232 "extension cable"

Absolute Maximum Ratings Thermal Information

VCC is grounded. 7 volts

Input voltage

Ground, ground, ground. -0.5V to (VCC+0.5V)

input/output voltage

A/Y, B/Z. -8V to +12.5V

reverse osmosis. -0.5V to (VCC+0.5V)

short circuit duration

Y, Z. Continuous electrostatic discharge rating. see spec sheet

operating conditions

temperature range

ISL8485ECX. 0oC to 70oC

ISL848SEIX. -40oC to 85oC

Thermal Resistance (Typical, Note 1) θJA (oC/W)

8 Ld SOIC package. 170

8 Ld PDIP packets. 140

Moisture Sensitivity (see Technical Brief TB363)

All packaging. Level 1

Maximum Junction Temperature (Plastic Packaging). 150 degrees Celsius

Maximum storage temperature range. -65 degrees Celsius to 150 degrees Celsius

Maximum lead temperature (10s for soldering). 300 degrees Celsius

(SOIC - lead only)

CAUTION: Stresses beyond those listed under "Absolute Maximum Ratings" may cause permanent damage to the device. This is a pressure rating and operation

Installation under the above or any other conditions stated in the operating section of this specification is not implied.

Note:

1. θJA is measured with components mounted on a low-efficiency thermal conductivity test board in free air.

Electrical specification test conditions: VCC=4.5V～5.5V; unless otherwise specified. Typical value is VCC=5V, TA=25oC (Note 2)

Electrical specification test conditions: VCC=4.5V～5.5V; unless otherwise specified. Typical values are VCC=5V, TA=25oC (Note 2) (continued)

Note:

2. All current entering the device pins is positive; all current flowing out of the device pins is negative. All voltages are referenced to equipment ground unless

otherwise specified.

3. When DE=0V, the supply current specification is valid for the loaded driver.

4. Applicable to peak current. See "Typical Performance Curves" for details.

5. When testing ISL8483E, keep RE=0 to prevent the device from entering SHDN.

6. When testing the ISL8483E, the high time of the retransmit signal must be short enough (usually <200ns) to prevent the device from entering SHDN.

7. Turn off the ISL8483E by making RE-high and DE-low. If the input is in this state for less than 50ns, the part is guaranteed not to enter a shutdown state. If the input is in this state for at least 600 ns, the part is guaranteed to have entered a shutdown state. See the "Low Power "Shutdown Mode" section.

8. Keep RE=VCC and set DE signal low time to >600ns to ensure the device goes to SHDN.

9. Set the retransmission signal high time to greater than 600ns to ensure that the device enters SHDN.

10. Devices meeting these constraints are denoted as "Single Unit Load (1ul)" transceivers. The RS-485 standard allows up to 32 unit loads on the bus.

application information

RS-485 and RS-422 are differential (balanced) data transmission standard environments for long distance or noisy environments. RS-422 is a subset of RS-485, so RS-485 transceivers are also RS-422 compliant. RS-422 is a point-to-multipoint (multi-drop) standard that allows only one driver and up to 10 (assuming a unit load device) receivers on each bus. RS-485 is a true multidrop standard that allows up to 32 devices (any combination of drivers and receivers) to be loaded in one unit. Allowed for multidrop operation, the RS-485 specification requires that the driver must not support any corruption. Another important advantage of RS-485 is the common mode range (CMR), which specifies that the driver output and receiver input can tolerate from +12V to -7V. RS-422 and RS-485 are used to run as long as 4000', then need to deal with wide CMR ground potential differences, as well as field cables. Receiver Characteristics These devices take advantage of differential input receiver noise immunity and common-mode rejection. Input sensitivity is ±200mV, meeting the required specifications for RS422 and RS-485. The receiver input impedance exceeds 4kΩ and meets the minimum 12kΩ. Receiver input function, common mode voltage is up to ±7V (ie +12V and -7V) outside the power supply, making it ideal for long network voltage is a real problem. All receivers include a "fail-on-open" feature that guarantees a high level receiver output unconnected (floating) if the receiver input.

The receiver is easy to meet the corresponding. The ISL8483E/85E receiver output is re-input through an active low. Driver Features The RS-485/422 driver is a differential output device that supplies at least 1.5V into a 54Ω load (RS-485) and at least 2V into a 100Ω load (RS-422). The driver features low propagation delay skew to maximize bit width and minimize EMI. The drivers for the ISL8483E/85E are three high DE inputs that can be passed active. The slew rate of the ISL8483E driver output is limited to minimize electromagnetic interference and to minimize unterminated or improperly terminated nets. The data rate limited versions of these transformations are up to 250kbps. The output ISL8485E driver is not limited, so the output faster transition time allows a data rate of at least 5Mbps. Data rates, cables and termination RS-485/422 is suitable for networks up to 4000' in length, but the maximum system data rate increases with transmission length. Devices running at 5Mbps are limited to under 100' in length, while the 250kbps version can be over 1000 feet in length. Twisted pair is the cable of choice for RS-485/422 networks. Twisted pair wires are prone to noise and other common-mode electromagnetically induced voltage signals that are differentially effectively rejected by receivers in these integrated circuits. When using 5Mbps, the device must be properly terminated to minimize reflections. Termination is not required to use the 250kbps version, however, termination is recommended unless power consumption is the most important concern.

For point-to-point or point-to-multipoint (single driver on bus) networks, the main cable should have a characteristic impedance (usually 120Ω) at its farthest end from the driver. In multi-receiver applications, the stub connecting the receiver to the main cable should be kept as short as possible. Multi-drop (multi-driver) systems require characteristic impedance across the main cable. The cables connecting the transceivers to the mains should be as short as possible. Built-In Drive Overload Protection As mentioned earlier, the RS-485 specification requires the drive to survive a worst-case bus race. The ISL848XE device meets this requirement with a driver output short-circuit current limit and on-chip thermal shutdown circuitry. The driver output stage contains a short-circuit current limit circuit that ensures that the output current exceeds the RS-485 specification, even at the limit of the common-mode voltage range. In addition, these devices utilize folding circuits that reduce short-circuit current, and therefore, when competing voltages exceed either supply. In the event of a major short circuit, the ISL848XE device also includes a thermal shutdown function when the mold temperature becomes too extreme. This eliminates power consumption, allowing death cooling. The driver drops about 15 degrees in the mold temperature. If the argument persists, the thermal shutdown/reentrant cycle repeats until the fault is resolved. The receiver is in thermal shutdown.

Low Power Shutdown Mode (ISL8483E only) These CMOS transceivers all use a fraction of the power their bipolar counterparts require, but the IS8483E includes a shutdown feature that reduces the already low quiescent ICC into 1nA fines. flow. Island 8483E enters whenever the receiver and driver are simultaneously disabled (RE=VCC and DE=GND) for at least 600 ns. Disabling the driver and the receiver less than 50ns guarantees that the ISL8483E will not go into shutdown. Note that when the ISL8483E is enabled from shutdown. See note 5-8 at the end of the Electrical Specifications table. ESD Protection All pins on these interface devices include a Class 3 Human Body Model (HBM) ESD protection structure, but the RS-485 pins (driver output and receiver input) include advanced structures that enable them to operate in excess of ±15kV HBM. RS-485 pins are especially vulnerable to ESD damage because they are often connected to exposed ports on the outside of the finished product. Simply touching a port pin or connecting cable can cause an ESD event that can destroy an unprotected IC. These new ESD structures protect the device whether it is powered or not, does not allow any latch protection to activate and does not degrade the RS-485 mechanism for a common mode range of -7V to +12V. This built-in ESD protection eliminates the need for board-level protection structures (eg, TVS diodes) and associated, unwanted capacitive loads.

Human Body Model Testing As the name suggests, this test method simulates the delivery of ESD events to the IC during human handling. The tester plugs the pin under test through a 1.5kΩ current-limiting resistor. This HBM method determines the ability of an IC to withstand ESD events that typically occur during handling and manufacturing. On this high ESD series, the survivability of the RS-485 pin discharge voltage exceeds ±15kV to ground.

Typical Performance Curves VCC=5V, TA=25oC, ISL8483E and ISL8485E; unless otherwise specified

Typical Performance Curves VCC=5V, TA=25oC, ISL8483E and ISL8485E; unless otherwise specified (continued)