SP335

RS232/RS485/RS422 Transceiver with Internal Termination
Data Sheet

Description

The SP335 is an advanced multiprotocol transceiver supporting RS-232, RS-485, and RS-422 serial standards. Integrated cable termination and multiple configuration modes allow all three protocols to be used interchangeably over a single cable or connector with no additional switching components. Full operation requires only four external charge pump capacitors.

The RS-485/RS-232 mode pin selects RS-485 mode when high, and RS-232 mode when low. In RS-485 mode, the TERM pin enables the differential 120Ω termination, and the HALF/FULL pin configures the transceiver as either half or full duplex.

The high speed drivers operate up to 20Mbps in RS-485/422 modes, and up to 1Mbps in RS-232 mode. All drivers can be slew limited to 250kbps in any mode to minimize electromagnetic interference (EMI) by setting the dedicated SLEW pin low.

All transmitter outputs and receiver inputs feature robust electrostatic discharge (ESD) protection to ±15kV IEC 61000-4-2 Airgap, ±15kV Human Body Model (HBM) and ±8kV IEC 61000-4-2 Contact. Each receiver output has full fail-safe protection to avoid system lockup, oscillation, or indeterminate states by defaulting to logic-high output level when the inputs are open, shorted, or terminated but undriven. No external biasing resistors are required.

The RS-232 receiver inputs include a 5kΩ pull-down to ground when in RS-232 mode. The RS-485/422 receiver inputs are high impedance (>96kΩ when termination is disabled), allowing up to 256 devices on a single communication bus (1/8th unit load).

The SP335 operates from a single power supply, either 3.3V or 5V, with low idle current. The shutdown mode consumes less than 1µA in low power standby operation with RS-232 receivers enabled.

Features

  • Pin-Selectable Cable Termination
  • No External Resistors Required for RS-485/422 Termination or Biasing
  • Robust ESD Protection:
    • ±15kV IEC 61000-4-2 Air Gap Discharge
    • ± 8kV IEC 61000-4-2 Contact Discharge
    • ±15kV Human Body Model (HBM)
  • 20Mbps RS-485 and 1Mbps RS-232 Data Rates
  • Pin-Selectable 250kbps Slew Limiting
  • Single Supply Operation from +3V to +5.5V
  • 1.65V to 5.5V Logic Interface VL pin
  • 2 Drivers, 2 Receivers RS-232/V.28
  • 1 Driver, 1 Receiver RS-485/422
    • Full or Half Duplex Configuration
    • 1/8th Unit Load, up to 256 receivers on bus
  • RS-485/422 Enhanced Receiver Fail-safe for open, shorted, or terminated but idle inputs
  • 10nA Shutdown Supply Current (typical)
  • Small 32 QFN package (5mm x 5mm)

Application

  • Software Programmable Serial Ports (RS-232, RS-422, RS-485)
  • Industrial and Single Board Computers
  • Industrial and Process Control Equipment
  • Point-Of-Sale Equipment
  • HVAC Controls and Networking Equipment
  • Building Security and Automation

Design Tools

Packaging

Pkg Code Details Quantities Dimensions PDF
QFN32 5x5 OPT3
  • JEDEC Reference:
  • MSL Pb-Free: L2 @ 260ºC
  • MSL SnPb Eutectic:
  • ThetaJA: 30
  • Bulk Pack Style: Tray
  • Quantity per Bulk Pack: 490
  • Quantity per Reel: 3000
  • Quantity per Tube: n/a
  • Quantity per Tray: 490
  • Reel Size (Dia. x Width x Pitch): 330 x 12 x 8
  • Tape & Reel Unit Orientation: Quadrant 1
  • Dimensions: mm
  • Length: 5
  • Width: 5
  • Thickness: 1.00
  • Lead Pitch: 0.5

Parts & Purchasing

Part Number Pkg Code RoHS Min Temp Max Temp Status Buy Now Order Samples
SP335ECR1-L QFN32 5x5 OPT3 0 70 Active Order
SP335ECR1-L/TR QFN32 5x5 OPT3 0 70 Active Order
SP335EER1-L QFN32 5x5 OPT3 -40 85 Active Order
SP335EER1-L/TR QFN32 5x5 OPT3 -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

Part Number MDS REACH
SP335ECR1-L Download Download
SP335EER1-L Download
SP335ECR1-L/TR Download
SP335EER1-L/TR Download
Additional Quality Documentation may be available, please contact customersupport@maxlinear.com.
Distribution Date Description File
07/21/2017 Qualification of alternate assembly subcon, ANST.

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.
 
 

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.

Yes, the center pad should be connected to ground with a minimum of 5 vias to the GND plane (one at each corner and one in the middle). It is common to use 9 vias to GND (3 rows of 3 vias inside the pad). This helps thermal dissipation / conduction and electrical requirements for the device.

No, the maximum fault tolerance of the above devices is ±18V only. However, the XR3305x and XR3315x families DO support up to ±60V fault tolerance. To find the device in the XR3305x and XR3315x families with the configuration you are looking for, use the parametric search https://www.exar.com/products/interface/serial-transceivers/rs485-422. The Fault Tolerance column is on the right side of the table. See the filters on the left for device selection. See Application Note ANI-23 https://www.exar.com/ani-23.pdf for more on fault testing of these devices.

For any voltage above ±60V, refer to diode manufacturers, such as the Bourns RS-485 transient protection for example below, for an external diode to absorb the transient or surge voltage for protection.

https://www.digikey.com/product-detail/en/bourns-inc/RS-485EVALBOARD1/RS-485EVALBOARD1-ND/2658335

or

https://www.digikey.com/product-detail/en/bourns-inc/RS-485EVALBOARD2/RS-485EVALBOARD2-ND/2658336

The best way to determine this is to go to maxlinear.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. Click on part number header or on the link at the bottom of the result.  This brings you to the product page. For example:

 
 
 

Click on Parts & Purchasing, highlighted with the blue arrow 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, the legend still present:

 
 
 

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

 
 
 

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.