Description
The SP3070E-3078E differential line transceivers are suitable for bidirectional communication on balanced multipoint bus transmission lines and comply with both RS485 and RS422 EIA Standards. Each device consists of a differential driver and differential receiver. All devices operate from a 3.3V power supply.High receiver input impedance allows a large number of transceivers to share a common data bus while maintaining signal margin and without excessive loading or use of expensive repeaters. The high impedance driver output is maintained over the entire common-mode voltage range from -7 to +12V. Receivers will failsafe to logic 1 output when inputs are open, shorted or terminated. Drivers include built-in short-circuit protection and a thermal-overload shutdown to protect against excessive power dissipation from bus contention or cable faults. All RS485 receiver inputs and driver outputs are ESD protected up to ±15kV (Air-Gap and Human Body Model) and up to ±8kV Contact discharge (IEC 1000-4-2).
For technical support or help choosing a product please email Exar’s Serial Technical Support group at: serialtechsupport@exar.com.
Features
- ±15kV ESD protection for RS485 pins
- 3.3V low-power operation
- Advanced receiver-failsafe protection for open, shorted or terminated lines
- Up to 256 Transceivers may share bus
- Very low load for 8x greater fan-out
- Hot Swap glitch protection RE and DE
- Thermal shutdown protects against driver contention
- Available in three industry standard footprints
- SP3070E, SP3073E and SP3076E in Full-Duplex (14 pin)
- SP3071E, SP3074E and SP3077E in Full-Duplex (8 pin)
- SP3072E, SP3075E and SP3078E in Half-Duplex (8 pin)
- Three applications-optimized speed grades
- SP3070-72E: 250kbps fully slew-limited
- SP3073-75E: 500kbps slew-limited
- SP3076-78E: 16Mbps high speed
- Small form factor SO-narrow packages
- Industrial (-40 to +85ºC) & Extended (-40 to +85ºC) temperature grades
Documentation
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Datasheet
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Application Notes
- ANI-13, RS-485 and RS-422 Physical Topologies
- ANI-20, Advanced Features of the SP3070E-SP3078E and SP3080E- SP3088E High Performance RS-485 Transceivers
- ANI-21, SP3070E-SP3078E Guidelines for Failsafe Biasing when Applied in Multi-Voltage Networks
- AN-207, Advantages of Enhanced Receiver Failsafe Features
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Product FAQs
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Product Brochure
Application
Design Tools
Packaging
Parts & Purchasing
| Part Number | Pkg Code | RoHS | Min Temp | Max Temp | Status | Buy Now | Order Samples |
|---|---|---|---|---|---|---|---|
| SP3077EEN-L | NSOIC8 | -40 | 85 | Active | Order | ||
| SP3077EEN-L/TR | NSOIC8 | -40 | 85 | Active | Order | ||
| SP3077EMN-L | NSOIC8 | -40 | 125 | OBS |
Suggested: SP3077EEN-L/TR |
||
| SP3077EMN-L/TR | NSOIC8 | -40 | 125 | OBS |
Suggested: SP3077EEN-L/TR |
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.
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.
Additional Quality Documentation may be available, please contact customersupport@maxlinear.com.
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.
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
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 kΩ, which equates to 1/10 of a unit load. Therefore, XR33152 allows more than 320 devices (32 x 10) on the bus.
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.
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.
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.