SP3082E

Advanced Failsafe RS-485/RS-422 Transceivers 1/8th Unit Load, Slew-Rate Limited, ±15kV ESD-Protected
Data Sheet

Description

The SP3080E-SP3088E family of RS-485 devices are designed for reliable, bidirectional communication on multipoint bus transmission lines. Each device contains one differential driver and one differential receiver. The SP3082E, SP3085E and SP3088E are half-duplex devices; other part numbers are full-duplex. All devices comply with TIA/EIA-485 and TIA/EIA-422 standards. Lead-free and RoHS compliant packages are available for all models.

These devices are ruggedized for use in harsh operating conditions over the entire common-mode voltage range from -7V to +12V. Receivers are specially designed to fail-safe to a logic high output state if the inputs are left un-driven or shorted. All RS-485 bus-pins are protected against severe ESD events up to ±15kV (Air-Gap and Human Body Model) and up to ±8kV Contact Discharge (IEC 1000- 4-2). Drivers are protected from excess current flow caused by bus contention or output short-circuits by both an internal current limit and a thermal-overload shutdown. Devices are rated for industrial (-40 to +85oC) operating temperatures. Receivers have exceptionally high input impedance, which places only 1/8th the standard load on a shared bus. Up to 256 transceivers may coexist while preserving full signal margin.

All devices operate from a single 5.0V power supply and draw negligible quiescent power. All versions except the SP3081E, SP3084E, and SP3087E may independently enable and disable their driver and receiver and enter a low power shutdown mode if both driver and receiver are disabled. All outputs maintain high impedance in shutdown or when powered-off.

For technical support or help choosing a product please email Exar’s Serial Technical Support group at:  serialtechsupport@exar.com.

Features

  • Half Duplex RS485 Transceiver
  • 5.0V Single Supply Operation
  • Slew rate controlled driver, Low EMI
  • 115kbps data rate
  • Receiver failsafe on open, short or terminated lines
  • 1/8th Unit Load, 256 transceivers on bus
  • Hot Swap glitch protection on control inputs
  • Driver short circuit current limit and thermal shutdown for overload protection
  • Ultra-low 400μA Quiescent Current
  • 1μA shutdown mode
  • Industry standard package footprints
  • Robust ESD Specifications:
    • ±15KV Human Body Model
    • ±8KV IEC1000-4-2 Contact Discharge

Application

Design Tools

Packaging

Pkg Code Details Quantities Dimensions PDF
NSOIC8
  • JEDEC Reference: MS-012
  • MSL Pb-Free: L1 @ 260ºC
  • MSL SnPb Eutectic: n/a
  • ThetaJA: 128.4ºC/W (std); 96.8ºC/W (fused)
  • Bulk Pack Style: Tube
  • Quantity per Bulk Pack: 98
  • Quantity per Reel: 2500
  • Quantity per Tube: 98
  • Quantity per Tray: n/a
  • Reel Size (Dia. x Width x Pitch): 330 x 12 x 8
  • Tape & Reel Unit Orientation: Quadrant 1
  • Dimensions: mm
  • Length: 4.90
  • Width: 3.90
  • Thickness: 1.75
  • Lead Pitch: 1.27

Parts & Purchasing

Part Number Pkg Code RoHS Min Temp Max Temp Status Buy Now Order Samples
SP3082EEN-L NSOIC8 -40 85 Active Order
SP3082EEN-L/TR NSOIC8 -40 85 Active Order
Show obsolete parts
Part Status Legend
Active - the part is released for sale, standard product.
EOL (End of Life) - the part is no longer being manufactured, there may or may not be inventory still in stock.
CF (Contact Factory) - the part is still active but customers should check with the factory for availability. Longer lead-times may apply.
PRE (Pre-introduction) - the part has not been introduced or the part number is an early version available for sample only.
OBS (Obsolete) - the part is no longer being manufactured and may not be ordered.
NRND (Not Recommended for New Designs) - the part is not recommended for new designs.

Quality Documents

Additional Quality Documentation may be available, please contact customersupport@maxlinear.com.
Distribution Date Description File
07/11/2017 Product Discontinuation Notification
02/15/2017 Qualification of alternate assembly subcon, ANST.
04/28/2016 Qualification of alternate assembly subcon, JCET.
07/03/2013 Addition of qualified 6 inch wafer processing line in Episil, in addition to the currently qualified 5 inch wafer processing line. Other change (foundry 6 inch wafer qualification).
07/02/2013 Qualification of an alternate qualified assembly supplier, ASE Chung-Li (Taiwan) for the 8L NSOIC package using copper wire bonding. Material change and alternate assembly supplier qualified.
05/06/2013 Qualified TSMC as an alternate foundry supplier. Qualified Cu wire bonding assembly process at Carsem, Ipoh, Malaysia and ASE, Chung-Li, Taiwan. Alternate foundry supplier.
03/08/2012 Wafer Fabrication Facility Wafer foundry request.
12/07/2009 Enhancement of NSOIC 8, NSOIC14 and NSOIC16 packages to Green (halogen-free) via Mold Compound & Die Attach Material. Enhance packages to be Green (halogen-free).
10/03/2008 Wafer Fabrication – Episil 1.2um CMOS To correct auto-doping of N-Well causing Vtp variation and to eliminate device leakage.

Frequently Asked Questions

For RS-232 it is 50 feet (15 meters), or the cable length equal to a capacitance of 2500 pF, at a maximum transmission rate of 19.2kbps. When we reduce the baud rate, it allows for longer cable length. For Example:

 

Baud Rate (bps)

Maximum RS-232 Cable Length (ft)

19200

50

9600

500

4800

1000

2400

3000

 
For RS-485 / RS-422 the data rate can exceed 10Mbps depending on the cable length. A cable length of 15 meters (50 feet) will do a maximum of 10Mbps. A cable length of 1200 meters (4000 feet) will do a maximum of 90kbps over 24 AWG gauge twisted pair cable (with 10 pF/ft). Refer to Annex A TIA/EIA-422-B.
 
 

As RS-422/RS-485 uses differential signaling, it is more immune to noise and longer cables and/or high data rates can be used, especially in noisy environments. Also, RS-485 allows for multi-point operation, up to 32 unit loads. Transceivers may use a fraction of a unit load, increasing the number of devices on the bus. For example, the XR33152 receiver input impedance is at least 120 k, which equates to 1/10 of a unit load. Therefore, XR33152 allows more than 320 devices (32 x 10) on the bus.

Fail Safe is an attempt to keep the output of the RS-485 receiver to a known state. Transceivers may have standard fail safe or advanced / enhanced receiver fail safe features. Standard fail safe supports open inputs while enhanced fail safe transceivers such as the SP339 and XR34350 support open input, shorted input and undriven terminated lines without external biasing. See Application Note ANI-22 for more detail.

 

Figure 1:  Standard Failsafe Receiver Sensitivity Range
 


 

 
Figure 2: Standard Failsafe with Open Input
 
 
 
Figure 3: Enhanced Failsafe Receiver Sensitivity Range
 
 
 
Figure 4:  Enhanced Failsafe with Open Input
 
 
 
Figure 5:  Enhanced Failsafe with Shorted Input
 
 
 
Figure 6:  Enhanced Failsafe with Un-driven terminated lines
 
 
 

Yes, this is possible using one RS-485 transceiver. The microcontrollers will have to be addressable and have tri-state outputs. The RS-485 device can be controlled by the host via the DE/RE pin. The micros will have to be in either receiving mode or tri-state mode when the RS-485 transceiver is transmitting data. When the host transmits it will have to send an address to the specific micro. If any micro transmits the transceiver will have to be in receiving mode and all other micros will have to be in receive or tri-state. So the host would have to initiate this sequence by addressing the micro first then switch the transceiver to receive.
The half duplex system would have a bus with one transceiver and multiple microcontrollers all tied to the bus. For 5V systems the SP485 family can be used. For 3V systems the SP3070 family can be used. The require speed will determine the part number. The SP3078 part runs up to speeds of 16Mbps.  See the parametric search on https://www.exar.com/products/interface/serial-transceivers/rs485-422 for more options.
Care must be taken to assure the transceiver can drive the multiple micros in RX mode.

Yes, the SP3080 family (SP3082E, SP3083E, SP3084E, SP3085E, SP3088E) also have the hot swap glitch protection on control inputs.

ESD tests are “destructive tests.” The part is tested until it suffers damage. Therefore parts cannot be 100% tested in production, instead a sample of parts are characterized during the product qualification. The test procedure consists of “zapping” pins with a given voltage using the appropriate model and then running the part through electrical tests to check for functionality or performance degradation.

ESD is caused by static electricity. In order for an ESD event to occur there must be a buildup of static charge. Very high charge levels are actually quite rare. In a normal factory environment, taking basic ESD precautions (grounding-straps, anti-static smocks, ionizers, humidity control, etc.) static levels can be kept below a few tens of volts. In an uncontrolled environment, like an office, static levels rarely get above 2000 volts. Under some worstcase conditions (wearing synthetic fabrics, rubbing against synthetic upholstered furniture, extremely low humidity)
levels can go as high as 12 to 15 thousand volts. Actually to get to 15000 volts or higher you would need to be in an uncomfortably dry environment (humidity below 10%) otherwise static charge will naturally dissipate through corona discharge. It would definitely be considered a “bad hair day.” Humans can generally feel a static shock only above 3000 volts. A discharge greater than 4000 volts can cause an audible “pop.” But repeated lower level discharges can be imperceptible and still may have a cumulative damaging effect on sensitive ICs. All ICs, even those with robust protection, can be damaged if they are hit hard enough or often enough.

Most ICs in a typical system are at greatest risk of ESD damage in the factory when the PCB is assembled and the system is being built. After the system is put together they are soldered onto the PCB and shielded within a metal or plastic system enclosure. Interface ICs are designed to attach to an external connector that could be exposed to ESD when a cable is plugged in or when a person or object touches the connector. These interface pins are most likely to see ESD exposure and therefore benefit from additional protection.

Actually the letter “E” could have two different meanings, depending on where it is in the part number. Most of our interface devices are available in different temperature grades. Commercial temperature (0 to 70C) has a “C” after the numeric part number. Industrial-extended temperature (-40 to +85C) use the letter E. So for example SP485CN is commercial and SP485EN is industrial. The second letter indicates the package type, in this case N for narrow-SOIC. Another E in the suffix indicates that this device has enhanced ESD protection, typically of ±15000Volts on the interface pins. Devices that do not have the enhanced ESD still contain built-in ESD protection of at least ±2000Volts. For example the SP485ECN is ESD rated up to ±15kV, and the SP485CN is rated for ±2kV HBM.

The best way to determine this is to go to exar.com and type the part into the search function. At or near the top of the results you should see something that looks like
 
 

In this example, we looked for XRA1201. When you hover over it, it will turn grey and you can click anywhere in the grey box. This brings you to the product page. For example:

 
 

Click on Parts & Purchasing, highlighted in yellow above. The screen changes to:

 

Notice the status column and the “Show obsolete parts” link:

 

A legend tells you the definition of the different statuses. Click on the “Show obsolete parts” link to see EOL or OBS part numbers along with the Active part numbers:

 
 

Another method to find out if a part is OBS or EOL is to click on SUPPORT:

 

And then Product Change Notifications

 
 

Type the part into the search, and click on one of the part numbers from the drop down menu. Then you can look for the Product Discontinuation Notice, which generally is at the top of the list, for example:

 
 

If you see this, it tells you that this particular orderable part has been discontinued and when the last order date is, or was. If you click on the file, then you can view the notice we sent about this if you purchased the part in the recent past. It may also advise of a replacement part. When an orderable part first becomes discontinued, Product Discontinuation Notices are sent are sent to those who have purchased the parts in the recent past, if purchased directly, with a dated opportunity to place a last order.