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Exar Corporation 48720 Kato Road, Fremont CA, 94538 • 50-668-707 • www.exar.com SP3485_00_0692

DESCRIPTION

  • RS-485 and RS-422 Transceiver
  • Operates from a single +3.3V Supply
  • Interoperable with +5.0V logic
  • Driver/Receiver Enable
  • -7V to +2V Common-Mode Input Voltage Range
  • Allows up to 32 transceivers on the serial bus
  • Compatibility with industry standard 7576 pinout
  • Driver Output Short-Circuit Protection SP3485 +3.3V Low Power Half-Duplex RS-485 Transceiver with 10Mbps Data Rate The SP3485 device is a +3.3V low power half-duplex transceiver that meets the specifica - tions of the RS-485 and RS-422 serial protocols. This device is pin-to-pin compatible with the Exar SP48, SP483 and SP485 devices as well as popular industry standards. The SP3485 features the Exar BiCMOS process, allowing low power operation without sacrificing performance. The SP3485 can meet the electrical specifications of the RS-485 and RS-422 serial protocols up to 0Mbps under load.

Exar Corporation 48720 Kato Road, Fremont CA, 94538 • 50-668-707 • www.exar.com SP3485_00_0692 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. Input Voltages Output Voltages Power Dissipation (derate 6.90mW/ºC above +70ºC)

ELECTRICAL CHARACTERISTICS

TAMB = TMIN to TMAX and VCC = +3.3V +/-5% unless otherwise noted. PARAMETERS MIN. TYP. MAX. UNITS CONDITIONS SP3485 DRIVER DC Characteristics Differential Output Voltage GND Vcc Volts Unloaded; R = ∞Ω ; Figure 1 Differential Output Voltage 2 Vcc Volts With Load; R = 50Ω (RS-422); Figure Differential Output Voltage .5 Vcc Volts With Load; R = 27Ω (RS-485); Figure Change in Magnitude of Driver Differential Output Voltage for Complimentary states

0.2 Volts R = 27Ω or R = 50Ω; Figure 1

3 Volts R = 27Ω or R = 50Ω; Figure 1

Input High Voltage 2.0 Volts Applies to DE, DI, RE Input Low Voltage 0.8 Volts Applies to DE, DI, RE Input Current +/-0 µA Applies to DE, DI, RE Driver Short Circuit Current VOUT = HIGH +/-250 mA -7V ≤ VO ≤ +12V; Figure 8 Driver Short Circuit Current VOUT = LOW +/-250 mA -7V ≤ VO ≤ +12V; Figure 8 SP3485 DRIVER AC Characteristics Maximum Data Rate 0 Mbps RE = VCC, DE = VCC Driver Input to Output, tPLH 20 40 60 ns Figures 2 & 9 Driver Input to Output, tPHL 20 40 60 ns Figures 2 & 9 Differential Driver Skew 2 0 ns |tDO- tDO2|, Figures 2 and 0 Driver Rise or Fall Time 5 20 ns From 0%-90%; Figures 3 and 0

Exar Corporation 48720 Kato Road, Fremont CA, 94538 • 50-668-707 • www.exar.com SP3485_00_0692 PARAMETERS MIN. TYP. MAX. UNITS CONDITIONS SP3485 DRIVER AC Characteristics continued Driver Enable to Output High 52 20 ns Figures 4 and Driver Enable to Output Low 60 20 ns Figures 5 and Driver Disable Time from Low 40 20 ns Figures 5 and Driver Disable Time from High 60 20 ns Figures 4 and SP3485 RECEIVER DC Characteristics Differential Input Threshold -0.2 +0.2 Volts -7V ≤ VCM ≤ +12V Input Hysteresis 20 mV VCM = 0V Output Voltage HIGH Vcc-0.4 Volts VID = +200mV, -.5mA Output Voltage LOW 0.4 Volts VID = -200mV, 2.5mA Three-State (High Impedance) Output Current +/- µA 0V ≤ VO ≤ VCC; RE = VCC Input Resistance 2 5 kΩ -7V ≤ VCM ≤ +12V Input Current (A, B); VIN = 2V +.0 mA DE = 0V, VCC = 0V or 3.6V, VIN = 2V Input Current (A, B); VIN = -7V -0.8 mA DE = 0V, VCC = 0V or 3.6V, VIN = -7V Short Circuit Current 7 60 mA 0V ≤ VCM ≤ VCC SP3485 RECEIVER AC Characteristics Maximum Data Rate 0 Mbps RE = 0V, DE = 0V Receiver Input to Output, tPLH 40 70 00 ns Figures 6 and 2 Receiver Input to Output, tPLH 70 ns TAMB = +25°C, Vcc = 3.3V, Figures 6 and 2 Receiver Input to Output, tPHL 40 70 00 ns Figures 6 and 2 Receiver Input to Output, tPHL 70 ns TAMB = +25°C, Vcc = 3.3V, Figures 6 and 2 Differential Receiver Skew 4 ns tRSKEW = |tRPHL- tRPLH|, Figures 6 and 2 Receiver Enable to Output Low 35 60 ns Figures 7 and 3, S closed, S2 open Receiver Enable to Output High 35 60 ns Figures 7 and 3, S2 closed, S open Receiver Disable from Low 35 60 ns Figures 7 and 3, S closed, S2 open Receiver Disable from High 35 60 ns Figures 7 and 3, S2 closed, S open POWER REQUIREMENTS Supply Current , No Load 000 2000 µA RE, DI = 0V or VCC ; DE = VCC Supply Current , No Load 800 500 µA RE = 0V, DI = 0V or VCC, DE = 0V TAMB = TMIN to TMAX and VCC = +3.3V +/-5% unless otherwise noted.

Exar Corporation 48720 Kato Road, Fremont CA, 94538 • 50-668-707 • www.exar.com SP3485_00_0692 PIN FUNCTION Pin - RO - Receiver output Pin 2 - RE - Receiver Output Enable Active LOW Pin 3 - DE - Driver Output Enable Active HIGH Pin 4 - DI - Driver Input Pin 5 - GND - Ground Connection Pin 6 - A - Non-Inverting Driver Output/Receiver Input Pin 7 - B - Inverting Driver Output/Receiver Input Pin 8 - Vcc - Positive Supply Pin Function SP3485

Exar Corporation 48720 Kato Road, Fremont CA, 94538 • 50-668-707 • www.exar.com SP3485_00_0692 The SP3485 is a member in the family of +3.3V low power half-duplex transceivers that meet the electrical specifications of the RS-485 and RS-422 serial protocols. This device is pin-to-pin compatible with the Exar SP48, SP483 and SP485 devices as well as popular industry standards. The SP3485 feature Exar's BiCMOS process allowing low power operation without sacrificing performance. Driver The driver outputs of the SP3485 are dif- ferential outputs meeting the RS-485 and RS-422 standards. The typical voltage output swing with no load will be 0 volts to +3.3 Volts. With a load of 54Ω across the differential outputs, the drivers can maintain greater than .5V voltage levels. The driver of the SP3485 has a driver enable control line which is active HIGH. A logic HIGH on DE (pin 3) will enable the differential driver outputs. A logic LOW on the DE (pin 3) will tri-state the driver outputs. The driver of the SP3485 operates up to 0Mbps. The 250mA I SC maximum limit on the driver output allows the SP3485 to withstand an infinite short circuit over the -7.0V to +2V common mode range without catastrophic damage to the IC. Receiver The SP3485 receiver has differential inputs with an input sensitivity of ±200mV. Input impedance of the receiver is typically 15kΩ (12kΩ minimum). A wide common mode range of -7V to +2V allows for large ground potential differences between systems. The receiver is equipped with a fail-safe feature that guarantees the receiver output will be in a HIGH state when the input is left uncon- nected. The receiver of the SP3485 operates up to 0Mbps. The receiver of the SP3485 has an enable control line which is active LOW. A logic LOW on RE (pin 2) will enable the differential receiver. A logic HIGH on RE (pin 2) of the SP3485 will disable the receiver. 0 0 +0.2V 0 0 -0.2V 0 0 0 Inputs Open

0 X Z

Table . Transmit Function Truth Table Table 2. Receive Function Truth Table

Exar Corporation 48720 Kato Road, Fremont CA, 94538 • 50-668-707 • www.exar.com SP3485_00_0692

Exar Corporation 48720 Kato Road, Fremont CA, 94538 • 50-668-707 • www.exar.com SP3485_00_0692

ORDERING INFORMATION

Model Temperature Range Package Types

REVISION HISTORy

0/5/02 -- Legacy Sipex Datasheet 06/9/2 .0.0 Convert to Exar Format. Update ordering information and add new Figure 8 - Driver Short Circuit Current Limit Test Circuit. Remove EOL device SP348. 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 writing, 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 202 EXAR Corporation Datasheet June 202 For technical support please email Exar's Serial Technical Support group at: serialtechsupport@exar.com Reproduction, in part or whole, without the prior written consent of EXAR Corporation is prohibited. Note: /TR = Tape and Reel