SP485R EXAR | Alldatasheet

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Technical content

Exar Corporation 48720 Kato Road, Fremont CA, 94538 • 50-668-707 • www.exar.com SP485R_00_072309

DESCRIPTION

FEATURES

  • Allows Over 400 Transceivers On A Transmission Line (/0th Unit Load)
  • High Impedance on Receiver Inputs (RIN = 150kΩ typical)
  • Half-Duplex Configuration Consistent With Industry Standard Pinout
  • -7V to +2V Common Mode Input Voltage Range
  • Low Power Consumption (250mW)
  • Separate Driver and Receiver Enable SP485R 1/10th Unit Load RS-485 Transceiver The SP485R is a pin-to-pin equivalent to our existing SP485 product and offers a high receiver input impedance. The higher receiver input impedance allows for connecting over 400 transceivers on a single transmission line without degrading the RS-485 driver signal. The device is packaged in a 8-pin plastic DIP or 8-pin narrow SOIC.

Figure 1. Typical Application Circuit

Exar Corporation 48720 Kato Road, Fremont CA, 94538 • 50-668-707 • www.exar.com SP485R_00_072309 ABSOLUTE MAXIMUM RATINGS These are stress ratings only and functional operation of the device at these ratings or any other above those indicated in the operation sections of the specifications below is not implied. Exposure to absolute maximum rating conditions for extended periods of time may affect reliability.

ELECTRICAL CHARACTERISTICS

Typically 25ºC @ VCC = +5V unless otherwise noted. PARAMETERS MIN. TYP. MAX. UNITS CONDITIONS LOGIC INPUTS VIL 0.8 Volts VIH 2.0 Volts LOGIC OUTPUTS VOL 0.4 Volts IOUT = -3.2mA VOH 2.4 Volts IOUT = .0mA RS-485 DRIVER DC Characteristics Open Circuit Voltage 6.0 Volts Differential Output Voltage .5 5.0 Volts RL = 54Ω, CL = 50pF Balance +/-0.2 Volts |VT| - |VT| Common-Mode Output 3.0 Volts Output Current 28.0 mA RL = 54Ω Short Circuit Current +/-250 mA Terminated in -7V to +2V RS-485 DRIVER AC Characteristics Maximum Data Rate 5 Mbps RL = 54Ω, Output Transition Time 30 ns Rise/fall time, 0% to 90% Propagation Delay, tPLH 60 00 ns See Figures 4 & 6, RDIFF = 54Ω, CL = CL2 = 00pF Propagation Delay, tPHL 60 00 ns See Figures 4 & 6, RDIFF = 54Ω, CL = CL2 = 00pF Driver Output Skew 5 5 ns see Figures 4 and 6, tSKEW = |tDPHL - tDPLH| RS-485 RECEIVER DC Characteristics Output Voltage Low, VOL 0.4 Volts Output Voltage High, VOH 2.4 Volts Tri-State Output Current +/- µA 0.4V ≤ VOUT ≤ 2.4V; RE = Vcc Power Dissipation (ØJA = 62ºC/W) (ØJA = 62ºC/W)

Exar Corporation 48720 Kato Road, Fremont CA, 94538 • 50-668-707 • www.exar.com SP485R_00_072309 PARAMETERS MIN. TYP. MAX. UNITS CONDITIONS RS-485 RECEIVER DC Characteristics (continued) Common Mode Range -7.0 +2.0 Volts Receiver Sensitivity +/-0.2 Volts -7V ≤ VCM ≤ +12V Input Impedance 20 50 kΩ -7V ≤ VCM ≤ +12V RS-485 RECEIVER AC Characteristics Maximum Data Rate Mbps Propagation Delay; tPHL 200 ns See Figures 4 & 8, RDIFF = 54Ω, CL = CL2 = 00pF Propagation Delay; tPLH 200 ns See Figures 4 & 8, RDIFF = 54Ω, CL = CL2 = 00pF Differential Receiver Skew 60 ns See Figures 4 & 8, RDIFF = 54Ω, CL = CL2 = 00pF, tSKEW = |tPHL - tPLH| RS-485 DRIVER Enable / Disable Time Driver Enable to Output Low 40 500 ns CL = 5pF, see Figures 5 and 7, S closed Driver Enable to Output High 40 500 ns CL = 5pF, see Figures 5 and 7, S2 closed Driver Disable Time from Low 40 500 ns CL = 5pF, see Figures 5 and 7, S closed Driver Disable Time from High 40 500 ns CL = 5pF, see Figures 5 and 7, S2 closed RS-485 RECEIVER Enable / Disable Time Receiver Enable to Output Low 40 500 ns CL = 5pF, see Figures 3 and 9, S closed Receiver Enable to Output High 40 500 ns CL = 5pF, see Figures 3 and 9, S2 closed Receiver Disable from Low 40 500 ns CL = 5pF, see Figures 3 and 9, S closed Receiver Disable from High 40 500 ns CL = 5pF, see Figures 3 and 9, S closed POWER REQUIREMENTS Supply Voltage VCC +4.75 +5.25 Volts Supply Current ICC, No Load 300 500 µA RE = Vcc or 0V, DE = 0V Supply Current ICC, No Load 500 900 µA RE = Vcc or 0V, DE = Vcc ENVIRONMENTAL Operating Temperature Commercial (..C..) 0 +70 ºC Industrial (..E..) -40 +85 ºC Storage Temperature -65 +50 ºC Typically 25ºC @ VCC = +5V unless otherwise noted.

Figure 2. Driver DC Test Load Circuit Figure 4. RS-485 Driver/Receiver Timing Test Figure 5. Driver Timing Test Load #2 Circuit Figure 3. Receiver Timing Test Load Circuit

1 Unit Load

Exar Corporation 48720 Kato Road, Fremont CA, 94538 • 50-668-707 • www.exar.com SP485R_00_072309 The SP485R is a low power RS-485 dif - ferential transceiver. Similar to the SP485, the SP485R contains a half-duplex driver and receiver with tri-state control. However, the SP485R is intended for increased con- nections on a single bus compared to the original RS-485 specifcation. The RS-485 standard is ideal for multi-drop applications where one bus can contain many drivers and/or receivers.The RS-485 standard implementation allows up to 32 transceivers to be connected on to the data bus. RS-485 is also specified for driving higher speeds over long cable lengths of up to 4000 feet. The SP485R exceeds the standard by allowing up to 400 receivers to share the bus DRIVERS The driver output complies with the RS- 485 electrical characteristics as specified by the standard. The output swings from 0V to Vcc and maintains greater than +.5V with a 54Ω load attached between the two outputs. In adhering to the RS-485 specifi- cation, the driver outputs inherently comply with the RS-422 standard. With a load of 100Ω between the two outputs, the driver can sustain at least +2.0V. The driver contains an enable pin (DE) which tri-states the output when DE is logic LOW. The outputs during the tri-state condition are at high impedance (>100kΩ). A logic HIGH enables the driver for normal operation. The driver can operate to at least 5Mbps. RECEIVERS The SP485R receiver has differential in - puts with an input sensitivity of lower than ±200mV. As mentioned above, the RS-485 specification allows up to 32 transceivers on the same bus. The SP485R allows over 400 transceivers on the same bus due to its high impedance of at least 120kΩ. This higher capacity allows more components to be at- tached to the same bus without degrading the signal quality. The drivers are still able to drive an equivalent 54Ω from the 320 transceivers with an input impedance of at least 120kΩ in parallel along with the two 125Ω cable termination resistors on each end. The receiver contains an enable pin (RE) which enables the receiver when a logic LOW is asserted. A logic HIGH will tri-state the receiver output and the inputs will maintain at least 120kΩ impedance. The reciever can operate to at least Mbps The receiver also contains a fail-safe feature which outputs a logic HIGH when the inputs are open as in a disconnected cable.

Exar Corporation 48720 Kato Road, Fremont CA, 94538 • 50-668-707 • www.exar.com SP485R_00_072309

Exar Corporation 48720 Kato Road, Fremont CA, 94538 • 50-668-707 • www.exar.com SP485R_00_072309

Exar Corporation 48720 Kato Road, Fremont CA, 94538 • 50-668-707 • www.exar.com SP485R_00_072309

ORDERING INFORMATION

Model Temperature Range Package Types

REVISION HISTORy

06/2/04 -- Legacy Sipex Datasheet 07/23/09 .0.0 Convert to Exar Format. Update ordering information as a result of discontinued Lead type package options per PDN 081126-01. Remove all reference to the dis- continued SP48R. Notice EXAR Corporation reserves the right to make changes to any products contained in this publication in order to improve design, performance or reliabil- ity. EXAR Corporation assumes no representation that the circuits are free of patent infringement. Charts and schedules contained herein are only for illustration purposes and may vary depending upon a user's specific application. While the information in this publication has been carefully checked; no responsibility, however, is assumed for inaccuracies. EXAR Corporation does not recommend the use of any of its products in life support applications where the failure or malfunction of the product can reasonably be expected to cause failure of the life support system or to significantly affect its safety or effectiveness. Products are not authorized for use in such applications unless EXAR Corporation receives, in writting, assurances to its satisfaction that: (a) the risk of injury or damage has been minimized ; (b) the user assumes all such risks; (c) potential liability of EXAR Corporation is adequately protected under the circumstances. Copyright 2009 EXAR Corporation Datasheet July 2009 Send your Interface technical inquiry with technical details to: uarttechsupport@exar.com Reproduction, in part or whole, without the prior written consent of EXAR Corporation is prohibited. Note: /TR = Tape and Reel