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Exar Corporation 48720 Kato Road, Fremont CA, 94538 • 510-668-7000 • www.exar.com SP3485_200_051916

DESCRIPTION

  • RS-485 and RS-422 Transceiver
  • Operates from a single +3.3V Supply
  • Interoperable with +5.0V logic
  • Driver/Receiver Enable
  • -7V to +12V Common-Mode Input Voltage Range
  • Allows up to 32 transceivers on the serial bus
  • Compatibility with industry standard 75176 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 SP481, SP483 and SP485 devices as well as popular industry standards. The SP3485 can meet the electrical specifications of the RS-485 and RS-422 serial protocols up to 10Mbps under load.

Exar Corporation 48720 Kato Road, Fremont CA, 94538 • 510-668-7000 • www.exar.com SP3485_200_051916 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 1 Differential Output Voltage 1.5 Vcc Volts With Load; R = 27Ω (RS-485); Figure 1 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 +/-10 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 10 Mbps RE = VCC, DE = VCC Driver Input to Output, tPLH 17 60 ns Figures 2 & 9 Driver Input to Output, tPHL 17 60 ns Figures 2 & 9 Differential Driver Skew 2 10 ns |tDO1- tDO2|, Figures 2 and 10 Driver Rise or Fall Time 5 20 ns From 10%-90%; Figures 3 and 10

Exar Corporation 48720 Kato Road, Fremont CA, 94538 • 510-668-7000 • www.exar.com SP3485_200_051916 PARAMETERS MIN. TYP. MAX. UNITS CONDITIONS SP3485 DRIVER AC Characteristics continued Driver Enable to Output High 35 120 ns Figures 4 and 11 Driver Enable to Output Low 30 120 ns Figures 5 and 11 Driver Disable Time from Low 20 120 ns Figures 5 and 11 Driver Disable Time from High 20 120 ns Figures 4 and 11 Driver Enable from Shutdown to Output High, tPSH 250 ns CL = 50pF, RL = 500Ω. Figures 4, 5, and 11 Driver Enable from Shutdown to Output Low, tPSL 250 ns Time to Shutdown, tSHDN 50 200 600 ns Notes 1 and 2 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, -1.5mA Output Voltage LOW 0.4 Volts VID = -200mV, 2.5mA Three-State (High Impedance) Output Current +/-1 µA 0V ≤ VO ≤ VCC; RE = VCC Input Resistance 12 kΩ -7V ≤ VCM ≤ +12V Input Current (A, B); VIN = 12V +1.0 mA DE = 0V, VCC = 0V or 3.6V, VIN = 12V 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 10 Mbps RE = 0V, DE = 0V Receiver Input to Output, tPLH 40 100 ns Figures 6 and 12 Receiver Input to Output, tPLH 70 ns TAMB = +25°C, Vcc = 3.3V, Figures 6 and 12 Receiver Input to Output, tPHL 35 100 ns Figures 6 and 12 Receiver Input to Output, tPHL 70 ns TAMB = +25°C, Vcc = 3.3V, Figures 6 and 12 Differential Receiver Skew 4 ns tRSKEW = |tRPHL- tRPLH|, Figures 6 and 12 Receiver Enable to Output Low 10 60 ns Figures 7 and 13, S1 closed, S2 open Receiver Enable to Output High 10 60 ns Figures 7 and 13, S2 closed, S1 open Receiver Disable from Low 10 60 ns Figures 7 and 13, S1 closed, S2 open Receiver Disable from High 10 60 ns Figures 7 and 13, S2 closed, S1 open TAMB = TMIN to TMAX and VCC = +3.3V +/-5% unless otherwise noted.

Exar Corporation 48720 Kato Road, Fremont CA, 94538 • 510-668-7000 • www.exar.com SP3485_200_051916 PIN FUNCTION Pin 1 - 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 TAMB = TMIN to TMAX and VCC = +3.3V +/-5% unless otherwise noted. Notes: 1. The transceivers are put into shutdown by bringing RE High and DE Low simultaneously for at least 600ns. If the control inputs are in this state for less than 50ns, the device is guaranteed to not enter shutdown. If the enable inputs are held in this state for at least 600ns the device is assured to be in shutdown. Note that the receiver and driver enable times increase significantly when coming out of shutdown. 2. This spec is guaranteed by design and bench characterization. PARAMETERS MIN. TYP. MAX. UNITS CONDITIONS Receiver Enable from Shutdown to Output High, tPRSH 1800 ns CL = 15pF, RL = 1kΩ. Figures 7 and 13 Receiver Enable from Shutdown to Output Low, tPRSL 1800 ns Time to Shutdown, tSHDN 50 200 600 ns Notes 1 and 2 POWER REQUIREMENTS Supply Current , No Load 425 2000 µA RE, DI = 0V or VCC ; DE = VCC Supply Current , No Load 300 1500 µA RE = 0V, DI = 0V or VCC, DE = 0V

Exar Corporation 48720 Kato Road, Fremont CA, 94538 • 510-668-7000 • www.exar.com SP3485_200_051916 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 SP481, 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 1.5V 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 10Mbps. The 250mA I SC maximum limit on the driver output allows the SP3485 to withstand an infinite short circuit over the -7.0V to +12V 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 12kΩ minimum. A wide common mode range of -7V to +12V 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 unconnected. The receiver of the SP3485 operates up to 10Mbps. 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. Low Power Shutdown Mode Low-power shutdown mode is initiated by bringing both RE high and DE low. In shutdown, the devices typically draw only 50nA of supply current. RE and DE can be driven simultaneously; the part is guaranteed not to enter shutdown if RE is high and DE is low for less than 50ns. If the inputs are in this state for at least 600ns, the parts are guaranteed to enter shutdown. Enable times tPRZH, tPZH, tPRZL and tPZL assume the part was not in a low-power shutdown state. Enable times t PRSH, tPSH, tPRSL and tPSL assume the parts were shut down. It takes drivers and receivers longer to become enabled from low-power shutdown mode (tPRSH, tPSH, tPRSL, tPSL) than from driver/receiver- disable mode (tPRZH, tPZH, tPRZL, tPZL).

0 X -50mV 1

0 X -200mV 0

Table 1. Transmit Function Truth Table Table 2. Receive Function Truth Table

Exar Corporation 48720 Kato Road, Fremont CA, 94538 • 510-668-7000 • www.exar.com SP3485_200_051916

Exar Corporation 48720 Kato Road, Fremont CA, 94538 • 510-668-7000 • www.exar.com SP3485_200_051916

ORDERING INFORMATION

Model Temperature Range Package Types

REVISION HISTORY

10/15/02 -- Legacy Sipex Datasheet 06/19/12 1.0.0 Convert to Exar Format. Update ordering information and add new Figure 8 - Driver Short Circuit Current Limit Test Circuit. Remove EOL device SP3481. 06/27/16 2.0.0 Update logo. Update description paragraph on page 1. Update timing specifications in electrical characteristics table on pages 2 and 3. Add Driver and Receiver Enable from Shutdown timing information on pages 3 and 4. Update typical supply current information on page 4. Update Figures 2, 4, 6, and 8. Update Figures 11 and 13 to add shutdown timing labels. Add low power shutdown section to page 7. Update transmit and receive truth tables on page 7. Update Receiver section on page 7. 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 2016 EXAR Corporation Datasheet June 2016 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