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SP3485 +3.3V Low Power Half-Duplex RS-485 Transceiver with 10Mbps Data Rate • 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 DESCRIPTION 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. Logic....................................-0.3V to +6.0V Drivers.................................-0.3V to +6.0V Receivers.........................................+/-5V VCC.....................................................................+6.0V Input Voltages Output Voltages Drivers.............................................+/-5V Receivers............................-0.3V to +6.0V Storage Temperature.......................-65˚C to +150˚C Power Dissipation 8-pin NSOIC...................................................600mW (derate 6.90mW/ºC above +70ºC) TAMB = TMIN to TMAX and VCC = +3.3V +/-5% unless otherwise noted. PARAMETERS TYP. SP3485 DRIVER DC Characteristics Differential Output Voltage Differential Output Voltage GND MIN. 2 Differential Output Voltage .5 Change in Magnitude of Driver Differential Output Voltage for Complimentary states Driver Common Mode Output Voltage Input High Voltage Input Low Voltage Input Current Driver Short Circuit Current VOUT = HIGH Driver Short Circuit Current VOUT = LOW SP3485 DRIVER AC Characteristics Maximum Data Rate Driver Input to Output, tPLH Driver Input to Output, tPHL Differential Driver Skew Driver Rise or Fall Time 2.0 0 20 20 ELECTRICAL CHARACTERISTICS MAX. UNITS CONDITIONS Vcc Vcc Vcc 0.2 Unloaded; R = ∞Ω ; Figure 1 Volts Volts With Load; R = 50Ω (RS-422); Figure Volts With Load; R = 27Ω (RS-485); Figure R = 27Ω or R = 50Ω; Figure 1 Volts 3 Volts R = 27Ω or R = 50Ω; Figure 1 0.8 +/-0 +/-250 Volts Volts µA mA Applies to DE, DI, RE Applies to DE, DI, RE Applies to DE, DI, RE -7V ≤ VO ≤ +12V; Figure 8 +/-250 mA -7V ≤ VO ≤ +12V; Figure 8 40 40 2 5 60 60 0 20 Mbps ns ns ns ns RE = VCC, DE = VCC Figures 2 & 9 Figures 2 & 9 |tDO- tDO2|, Figures 2 and 0 From 0%-90%; Figures 3 and 0 Exar Corporation 48720 Kato Road, Fremont CA, 94538 • 50-668-707 • www.exar.com SP3485_00_0692 2

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

PIN FUNCTION Pin Function SP3485 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 Exar Corporation 48720 Kato Road, Fremont CA, 94538 • 50-668-707 • www.exar.com SP3485_00_0692 4

TEST CIRCUITS D VOD Vcc R R VOC GENERATOR (NOTE 1) 50Ω S1 D VCC VDM R L = 27Ω OUT C L = 15pF (NOTE 2) Figure . Driver DC Test Load Circuit Figure 2. Driver Propagation Delay Test Circuit VOM = ≈ 1.5V VOH + VOL 2 CL RL = 60Ω OUT GENERATOR (NOTE 1) 50Ω D VCC S1 D CL = 50pF (NOTE 2) OUT RL = 110Ω GENERATOR (NOTE 1) 50Ω C L = 15pF (NOTE 2) VOM = ≈ 1.5V VOH + VOL 2 Figure 3. Driver Differential Output Delay and Transition Time Circuit. Figure 4. Driver Enable and Disable Timing Circuit, Output High 0V OR 3V D GENERATOR (NOTE 1) 50Ω S1 C L = 50pF (NOTE 2) VCC R L = 110Ω OUT GENERATOR (NOTE 1) 50Ω 1.5V 0V VID R OUT CL = 15pF (NOTE 2) VOM = VCC 2 Figure 5. Driver Enable and Disable Timing Circuit, Output Low Figure 6. Receiver Propagation Delay Test Circuit S1 S2 VCC S3 1.5V -1.5V VID R GENERATOR (NOTE 1) 50Ω 1k CL = 15pF (NOTE 2) DE = 0 or Vcc DI = 0 or Vcc D A/Y B/Z IOS D 100Ω -7V to +12V V Figure 7. Receiver Enable and Disable Timing Circuit Figure 8. Driver Short Circuit Current Limit Test NOTE : The input pulse is supplied by a generator with the following characteristics: PRR = 250kHz, 50% duty cycle, tR < 6.0ns, ZO = 50Ω. NOTE 2: CL includes probe and stray capacitance. Exar Corporation 48720 Kato Road, Fremont CA, 94538 • 50-668-707 • www.exar.com SP3485_00_0692 5

INPUT Y OUTPUT Z OUTPUT 3V 0V VOH VOL VOH VOL 1.5V tPLH 1.5V tPHL VOM VOM tPHL tPLH VOM VOM VOM = VOH + VOL 2 ≈ 1.5V SWITCHING WAVEFORMS IN 1.5V 1.5V tDO1 tDO2 90% 90% OUT 50% 10% tTD 50% 10% tTD 3V 0V 2.0V -2.0V Figure 9. Driver Propagation Delay Waveforms Figure 0. Driver Differential Output Delay and Transition Time Waveforms DE OUTPUT HIGH OUTPUT LOW 3V 0V VOH 0V VCC VOL 1.5V tPZH 1.5V tPHZ VOM 0.25V tPZL tPLZ VOM 0.25V VOM = VOH + VOL 2 ≈ 1.5V Figure . Driver Enable and Disable Timing Waveforms INPUT OUTPUT 3V 0V VCC 0V 1.5V tRPLH 1.5V tRPHL VOM VOM VOM = VCC 2 Figure 2. Receiver Propagation Delay Waveforms S1 is open S2 is closed S3 = 1.5V 1.5V tPRHZ 10% 1.5V tPRZH tPRSH S1 is closed S2 is open S3 = -1.5V 1.5V tPRLZ 10% 1.5V tPRZL tPRSL 1.5V 3V 0V VCC VOL RE 1.5V OUTPUT RE OUTPUT 3V 0V VOH 0V Figure 3. Receiver Enable and Disable Waveforms Exar Corporation 48720 Kato Road, Fremont CA, 94538 • 50-668-707 • www.exar.com SP3485_00_0692 6

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 ISC 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. DESCRIPTION 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. INPUTS OUTPUTS RE X X X DE 0 LINE CONDITION No Fault No Fault X B 0 Z DI 0 X A 0 Z Table . Transmit Function Truth Table INPUTS OUTPUTS RE 0 0 0 DE 0 0 0 0 A - B +0.2V -0.2V Inputs Open X R 0 Z Table 2. Receive Function Truth Table Exar Corporation 48720 Kato Road, Fremont CA, 94538 • 50-668-707 • www.exar.com SP3485_00_0692 7

Exar Corporation 48720 Kato Road, Fremont CA, 94538 • 50-668-707 • www.exar.com SP3485_00_0692 8

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SP3485EEN(SP3485EN).pdf

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