The ISL8308xE is a BiCMOS, ESD protected, 5V power supply that meets the RS-485 and RS-422 single-transceiver balanced communication standards. Each driver output, and receiver input, is protected against ±15kV ESD strikes without latching, and unlike competing products, this Intersil series is specified for a 10% tolerance supply (4.5V to 5.5V). The bus current of these devices is very low (+125µA/-75µA), so they provide a true "1/8 unit load" to the RS-485 bus. This allows up to 256 transceivers on the network to use repeaters without violating the RS-485 specification's maximum 32 unit load. For example, in a remote utility meter reading system, a single meter reading is transmitted to the concentrator over an RS-485 network, thus allowing the high node count to minimize the number of repeaters required. All data then goes through an access port or wireless link. The receiver (Rx) input has a "complete fail-safe" design, where if the Rx input is floating, the Rx output is guaranteed to be logic high, shorted, terminated but not torn. ISL 83080E, ISL 83082E, ISL 83083E, ISL 83084E, ISL83085E utilize slew rate limiting drivers that reduce EMI and minimize improperly terminated reflective transmission lines, or multi-drop and multi-drop applications. The slew rate limited version also includes receiver input filtering to enhance the presence of slow input signals. Hot-swap circuitry ensures that the Tx and Rx outputs remain in a high-impedance state until the power supply stabilizes and the Tx output is fully short-circuit protected. Island 83080E, Island 83083E, Island 83084E, Island 83086E are configured for full duplex (separate Rx input and Tx output pins) applications. The half-duplex version of the multiplexed Rx allows the input of the transceiver output and the transmit output to disable functions in the 8 Ld packets.

feature

Lead-free available (RoHS compliant)

RS-485 input/output pins are ESD protected. Level 3 ESD protection (HBM…) on all pins of 5kV high voltage motors. >7kV

Miniature MSOP package saves 50% board space

Fully fail-safe (open, shorted, terminated and floating) receiver

Hot Swap Circuitry (ISL83080E, ISL83082E, ISL83083E, Island 83085E) - Tx and Rx outputs on power up/down

True 1/8 unit load allows up to 256 devices on the bus

Specified as a single 5V, 10% tolerance, supply

high data rate. up to 10Mbps

Low quiescent supply current. 530µA ultra-low shutdown supply current. 70 nanometers

-7V to +12V Common Mode Input Voltage Range

Half and full duplex pins

Tri-state Rx and Tx outputs (except ISL83084E)

Drive Current Limit and Thermal Shutdown Overload Protection

application

Automatic utility meter reading system

High Node Count Systems

factory automation

Fieldbus network

security camera network

Building Environment Control System

Industrial/Process Control Networks

notes:

1. Add "-T" suffix for tapes and reels. See TB347 for reel specifications.

2. These Intersil lead-free plastic packaged products feature a special lead-free material set, molding compound/mold join material and 100% matte tinplate plus annealing (e3 termination treatment, RoHS compliant, with SnPb and lead-free soldering operations compatible). Intersil's lead-free products are classified as MSL at lead-free peak reflow temperatures and meet or exceed the lead-free requirements of the IPC/JEDEC J standard - 020.

Absolute Maximum Ratings Thermal Information

VCC is grounded. 7V input voltage ground, ground, ground. -0.3V to (VCC+0.3V) input/output voltages A, B, Y, Z. -9V to +13VA, B, Y, Z (transient pulse via 100, Note 14). ±75V reverse osmosis. -0.3V to (VCC+0.3V) Short Circuit Duration Y, Z. Continuous electrostatic discharge rating. See Spec Sheet Thermal Resistance (Typical, Note 3) θJA (°C/Watt)

8 Ld SOIC package. 105

8 Ld MSOP packs. 140

Pack of 10 Ld MSOPs. 190

14 Ld SOIC package. 128

Maximum Junction Temperature (Plastic Packaging). +150 degrees Celsius

Maximum storage temperature range. -65°C to +150°C

operating conditions

temperature range. -40°C to +85°C

NOTE: Do not operate at or near the maximum ratings listed for extended periods of time. Exposure to these conditions may compromise product reliability and cause failures not covered by warranty.

Note:

3. In free air, measure JA with components mounted on a high-efficiency thermal conductivity test board.

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

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

notes:

4. Unless otherwise specified, parameters with minimum and/or maximum limits are 100% tested at +25°C. Temperature limits determined by characterization are also not production testing.

5. All currents into device pins are positive; all currents out of device pins are negative. All voltages are referenced to equipment ground unless otherwise specified.

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

7. Applicable to peak current. See "Typical Performance Curves" at the beginning of page 13 for details.

8. Keep RE=0 to prevent the device from entering SHDN.

9. The retransmit high time must be short enough (typically <100ns) to prevent the device from entering SHDN.

10. Turn off the transceiver by driving RE high and DE low. If the input is in this state for less than 60ns, the part is guaranteed not to enter the 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 "Low Power Shutdown Mode",

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

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

13. Not applicable to ISL83084E.

14. Tested per TIA/EIA-485-A Section 4.2.6 (±75V for 15µs at 1% duty cycle).

15. Limits determined by characterization, no production testing.

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 one 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 signals in the range of +12V to -7V. RS-422 and RS-485 are used for lengths up to 4000' and therefore 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 RS-422 and RS-485. The receiver input resistance of 96k exceeds the RS-4224k specification and is 8 times the load (UL) requirement for RS-485” devices with a minimum of 12k. Therefore, these products are called "one-eighth UL" transceivers, and there can be up to 256 of these devices on a network and still comply with the RS-485 loading specification. 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 "complete fail-safe" feature that guarantees a high level receiver output if the receiver input is left unconnected (floating) or shorted. The receivers are easily catered for by the corresponding drivers, and all receiver outputs are via the active low RE input (except the island 83084E).

Driver function

The RS-485/RS-422 driver is a differential output device that supplies at least 1.5V across a 54 load (RS-485) and at least 2V across a 100 load (RS-422). The driver features low propagation delay skew to maximize bit width and minimize EMI. All drives are active through the three states of the high DE input (except for the island 83084E). The 115kbps and 500kbps driver outputs are slew rate limited to minimize EMI and minimize reflections on unterminated or improperly terminated networks. Output ISL83086E, ISL83088E drivers are not limited, so faster output transition time allows data rates of at least 10Mbps.

Hot plug function

When a device is powered, there is a time when the processor or ASIC driving the RS-485 controlled timing lines (DE, RE) cannot ensure that the RS-485 Tx and Rx outputs remain disabled. If the device is connected to the bus, the driver may crash the car if it starts up too early when the power is turned on. To avoid this, the ISL83080, ISL83082, ISL83083, ISL83085 versions include a "plug" function. The circuit monitors VCC to ensure power-up and power-down, the Tx and Rx outputs remain disabled, regardless of the state of DE and RE, if VCC is less than 3.4 V. This gives the processor/ASIC a chance to stabilize and drive the RS-485 control lines to the correct state.

ESD protection

All pins on these devices include a Level 3 Human Body Model (HBM) ESD protection structure, but the RS-485 pins (driver output and receiver input) include advanced structures that allow them to survive ESD events 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 or not it is powered on, 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. Data Rates, Cables, and Terminations RS-485/RS-422 are used for network lengths up to 4000', but the maximum system data rate increases with transmission length. Devices operating at 10Mbps are limited to under 100' in length, while the 115kbps version can operate at full data rate up to 1000 feet in length. Twisted pair is the cable network of choice for RS-485/RS-422. Twisted-pair cables are prone to noise other common electromagnetically induced voltage-mode signals that are effectively used by differential receivers in these integrated circuits. Must be properly terminated (devices when using 10Mbps) to minimize reflections. Termination is not required to use the 115kbps 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 120) 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 drivers to survive the worst bus accidents unscathed. These devices meet this requirement by shorting the driver outputs to circuit current limiting, and chip thermal shutdown circuits. 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. Additionally, these devices utilize folding circuits to reduce short circuits when competing voltages exceed either supply. In the event of a major short circuit, the device also includes a thermal shutdown feature that disables the driver when the die temperature is too high. This eliminates power consumption and allows the die to cool. The drive is automatically re-enabled after this mold temperature drops about +15°C. If contention persists, the shutdown/reenable cycle repeats until the fault clears. The receiver remains operational during thermal shutdown. Low-Power Shutdown Mode These CMOS transceivers all use a fraction of the power requirements of their bipolar counterparts, but they also include a shutdown function (except for the ISL83084E) that reduces the already low quiescent ICC to a trickle of 70nA. These are disabled whenever the receiver and driver are simultaneously disabled (RE=VCC and DE=GND) for a period of at least 600 ns. Disabling the driver and the receiver less than 60ns guarantees that the transceiver will not go into a shutdown state. Note that the transceiver is enabled from shutdown. See Notes 8 to 12, page 9 at the end of the "Electrical Specifications Sheet" for more information.

Typical performance curve VCC=5V, TA=+25°C; unless otherwise specified

Typical Performance Curve VCC=5V, TA=+25°C; unless otherwise specified (continued)

Typical Performance Curve VCC=5V, TA=+25°C; unless otherwise specified (continued)