MAX3485ED

3.3V, 10Mbps Half-Duplex RS-485/RS-422 Transceivers MAX3485 FEATURES • • • • • • • • • Operates from a Single 3.3V Supply Interoperable with +5.0V Logic −7V to 12V Common-Mode Input Voltage Range Three-State Outputs Driver/ Receiver Enable Half-Duplex Communication Allows up to 32 Transceivers on the Bus Data Rate up to 10 Mbps Current-Limiting and Thermal Shutdown for Driver Overload Protection • ESD Specifications ±15kV IEC61000-4-2 Air Discharge ±8kV Human Body Model SOP-8 ORDERING INFORMATION APPLICATIONS • • • • • • • Device Package MAX3485ED SOP-8 Low Power RS-485 Systems Telecommunications Packet Switching Industrial-Control Local Area Networks Data Concentration Data Multiplexers Integrated Services Digital Network (ISDN) DESCRIPTION The MAX3485 is a low-power half-duplex transceiver that meets the specifications of RS-485 and RS-422. IC contains one driver and one receiver. The driver slew rates is not limited, allowing them to transmit up to 10Mbps. These transceivers draw between 120µA and 500µA of supply current when unloaded or fully loaded with disabled drivers. All parts operate from a single 3.3V supply. Drivers are short-circuit current limited and are protected against excessive power dissipation by thermal shutdown circuitry that places the driver outputs into a high-impedance state. The receiver input has a fail-safe feature that guarantees a logic-high output if the input is open circuit. The ESD tolerance is more than ±8kV for both Human Body Model and ±15kV for IEC61000-4-2 Air Discharge Method on this device. Apr. 2020 – R1.0 1/13 HTC 3.3V, 10Mbps Half-Duplex RS-485/RS-422 Transceivers MAX3485 ABSOLUTE MAXIMUM RATINGS (Note 1) CHARACTERISTIC SYMBOL MIN. MAX. UNIT VCC −0.3 6.0 V Control Input Voltage VRE, VDE −0.3 6.0 V Driver Input Voltage VDI −0.3 6.0 V Driver Output Voltage VA, VB −15 15 V Receiver Input Voltage VA, VB −15 15 V VRO −0.3 VCC + 0.3 V Junction Temperature Range TJ −40 125 °C Storage Temperature Range TSTG −65 150 °C Supply Voltage Receiver Output Voltage Note 1. Stresses beyond those listed under Absolute Maximum Ratings may cause permanent damage to the device. These are stress ratings only and functional operation of the device at these or any other conditions beyond those indicated under Recommended Operating Conditions is not implied. Exposure to absolute-maximum-rated conditions for extended periods may affect device reliability. RECOMMENDED OPERATING CONDITIONS (Note 2) CHARACTERISTIC SYMBOL MIN. MAX. UNIT Supply Voltage VCC 0 3.3 ± 5% V Ambient Temperature Range TA −40 85 °C Note 2. The device is not guaranteed to function outside its operating ratings. ORDERING INFORMATION Package Order No. Description Supplied As Status SOP-8 MAX3485ED RS-485/ RS-422 Transceivers Tape & Reel Active Apr. 2020 – R1.0 2/13 HTC 3.3V, 10Mbps Half-Duplex RS-485/RS-422 Transceivers MAX3485 PIN CONFIGURATION RO 1 8 VCC RE 2 7 B DE 3 6 A DI 4 5 GND SOP-8 PIN DESCRIPTION Pin No. Pin Name 1 RO Receiver Output 2 RE Receiver Output Enable. Active Low 3 DE Driver Output Enable. Active High 4 DI Driver Input 5 GND 6 A Non-Inverting Driver Output/ Non-Inverting Receiver Input 7 B Inverting Driver Output/ Inverting Receiver Input 8 VCC Apr. 2020 – R1.0 Pin Function Ground Power Supply 3/13 HTC 3.3V, 10Mbps Half-Duplex RS-485/RS-422 Transceivers MAX3485 BLOCK DIAGRAM VCC RO R RE B DE A DI D GND Apr. 2020 – R1.0 4/13 HTC 3.3V, 10Mbps Half-Duplex RS-485/RS-422 Transceivers MAX3485 TYPICAL APPLICATION RO R RO R B B RE RE RT RT A A DE DI DE D B B A R RO R D RE DE D A DI RO DI D RE DE DI < Typical RS-485 Network with Half-Duplex Transceivers > Apr. 2020 – R1.0 5/13 HTC 3.3V, 10Mbps Half-Duplex RS-485/RS-422 Transceivers MAX3485 DC ELECTRICAL CHARACTERISTICS VCC = 3.3V, TA = 25°C, unless otherwise noted. PARAMETER SYMBOL TEST CONDITIONS MIN TYP MAX GND - VCC With Load, RL = 50Ω (RS-422), Figure 1 1 - VCC With Load, RL = 27Ω (RS-485), Figure 1 0.6 - VCC Unloaded, RL = ∞, Figure 1 Differential Output Voltage VOD UNIT V Change in Magnitude of Driver Differential Output Voltage for (NOTE 3) Complimentary States ΔVOD RL = 27Ω or RL = 50Ω, Figure 1 - - 0.2 V Driver Common- Mode Output Voltage VOC RL = 27Ω or RL = 50Ω, Figure 1 - - 3.0 V Input High Voltage VIH DE, DI, RE 2.0 - - V Input Low Voltage VIL DE, DI, RE - - 0.6 V Logic Input Current IIN1 DE, DI, RE - - ±10 µA Driver Short-Circuit Output Current IOSD VOUT = High or Low, −7V ≤ VOUT ≤ 12V - - ±250 mA Receiver Differential Input Threshold VTH −7V ≤ VCM ≤ 12V −0.2 - 0.2 V Receiver Input Hysteresis ΔVTH VCM = 0V - 20 - mV Receiver Output High Voltage VOH IOUT = −1.5mA, VID = 200mV, Figure 2 VCC−0.4 - - V Receiver Output Low Voltage VOL IOUT = 2.5mA, VID = 200mV, Figure 2 - - 0.4 V Three-State (High Impedance) Output Current at Receiver IOZR 0 ≤ VOUT ≤ VCC, RE = VCC - - ±1.0 µA Receiver Input Resistance RIN −7V ≤ VCM ≤ 12V 12 15 - kΩ VIN = 12V - 1.0 mA IIN2 DE = 0V, VCC = 0V or 3.5V - Receiver Input Current (A, B) VIN = −7V - - −0.8 mA IOSR 0V ≤ VOUTR ≤ VCC 7 - 60 mA DE = VCC, RE = 0V or VCC - 425 2000 DE = 0V, RE = 0V - Receiver Short Circuit Output Current Supply Current ICC No Load, DI = 0V or VCC µA 300 1500 Note 3. ΔVOD and ΔVOC are the changes in VOD and VOC, respectively, when the DI input changes state. Apr. 2020 – R1.0 6/13 HTC 3.3V, 10Mbps Half-Duplex RS-485/RS-422 Transceivers MAX3485 AC ELECTRICAL CHARACTERISTICS VCC = 3.3V, TA = 25°C, unless otherwise noted. PARAMETER SYMBOL Maximum Data Rate TEST CONDITIONS DE = RE = VCC or 0V MIN TYP MAX UNIT 10 - - Mbps Driver Differential Output Transition Time tTD Figure 3 - 5 20 ns Driver Input to Output Propagation Delay, Low-to-High Level tPLH Figure 4 - 17 60 ns Driver Input to Output Propagation Delay, High-to-Low Level tPHL Figure 4 - 17 60 ns Figure 4, |tPLH − tPHL| - 2 10 ns Driver Propagation Delay Skew tSKEW Driver Output Enable Time to High tPZH Figure 5 - 35 120 ns Driver Output Enable Time to Low tPZL Figure 6 - 30 120 ns Driver Output Disable Time from High tPHZ Figure 5 - 20 120 ns Driver Output Disable Time from Low tPLZ Figure 6 - 20 120 ns Receiver Input to Output Propagation Delay, Low-to-High Level tRPLH Figure 7 - 40 100 ns Receiver Input to Output Propagation Delay, High-to-Low Level tRPHL Figure 7 - 35 100 ns Figure 7, |tRPLH − tRPHL| - 4 - ns Differential Receiver Propagation Delay Skew tRSKEW Receiver Output Enable Time to Low tPRZL Figure 8 - 10 60 ns Receiver Output Enable Time to High tPRZH Figure 8 - 10 60 ns Receiver Output Disable Time from Low tPRLZ Figure 8 - 10 60 ns Receiver Output Disable Time from High tPRHZ Figure 8 - 10 60 ns Apr. 2020 – R1.0 7/13 HTC 3.3V, 10Mbps Half-Duplex RS-485/RS-422 Transceivers MAX3485 FUNCTION TABLE Transmitting Receiving Inputs Outputs Inputs Output RE DE DI B A RE DE A−B RO X 1 1 0 1 0 0 ≥ +0.2V 1 X 1 0 1 0 0 0 ≤ −0.2V 0 0 0 X Z Z 0 0 Inputs Open 1 1 0 X Z Z 1 0 X Z X: Don’t Care Apr. 2020 – R1.0 Z: High Impedance 8/13 HTC 3.3V, 10Mbps Half-Duplex RS-485/RS-422 Transceivers MAX3485 PARAMETER MEASUREMENT INFORMATION RL 2 VID R VOD D RL 2 VCC 0V VOC IOL VOL VOH IOH (+) (−) Fig. 2. Receiver VOH and VOL Fig. 1. Driver VOD and VOC 3V IN CL RL = 60Ω D GENERATOR (NOTE 4) 1.5V 1.5V OUT 0V tDO1 50Ω tDO2 OUT CL = 15pF (NOTE 5) ≈ 2V 90% 90% VCC 50% 50% 10% 10% tTD ≈ − 2V tTD Fig. 3. Driver Differential Output Delay and Transition Times 3V IN VOM 1.5V 1.5V 0V tPLH RL = 27Ω tPHL VOH S1 OUT D GENERATOR (NOTE 4) 50Ω A OUT CL = 15pF (NOTE 5) VOM VOM VOL VCC tPHL VOM = VOH + VOL 2 tPLH VOH ≈ 1.5V B OUT VOM VOM VOL Fig. 4. Driver Propagation Delay Apr. 2020 – R1.0 9/13 HTC 3.3V, 10Mbps Half-Duplex RS-485/RS-422 Transceivers MAX3485 3V S1 0V or 3V D OUT DE 1.5V 1.5V RL = 110Ω CL = 50pF 0V (NOTE 5) GENERATOR (NOTE 4) t PHZ t PZH 50Ω VOH 0.25V VOM = VOH + VOL 2 VOM OUT ≈ 1.5V 0V Fig. 5. Driver Enable and Disable Times, Output High VOM 3V DE RL = 110Ω 1.5V 1.5V S1 0V or 3V 0V OUT D tPLZ tPZL CL = 50pF (NOTE 5) GENERATOR (NOTE 4) VCC OUT 50Ω VOM 0.25V VOL Fig. 6. Driver Enable and Disable Times, Output Low 3V GENERATOR (NOTE 4) 50Ω VID R OUT IN 1.5V 1.5V 0V CL = 15pF tRPLH (NOTE 5) tRPHL VCC 1.5V 0V VOM = VCC OUT VOM VOM 2 0V Fig. 7. Receiver Propagation Delay Apr. 2020 – R1.0 10/13 HTC 3.3V, 10Mbps Half-Duplex RS-485/RS-422 Transceivers 1.5V S1 S3 VCC 1kΩ −1.5V MAX3485 VID R S2 CL = 15pF (NOTE 5) GENERATOR (NOTE 4) 50Ω 3V 3V RE 1.5V S1 OPEN S2 CLOSED S3 = 1.5V 1.5V RE 1.5V S1 CLOSED S2 OPEN S3 = ?1.5V 1.5V 0V 0V tPRHZ tPRLZ tPRZH VCC VOH 10% OUT tPRZL OUT 1.5V 0V 1.5V 10% VOL Fig. 8. Receiver Enable and Disable Times Note 4. The input pulse is supplied by a generator with the following characteristics: PRR = 250kHz, 50% duty cycle, tr ≤ 6.0ns, ZO = 50Ω. Note 5. CL includes probe and stray capacitance. Apr. 2020 – R1.0 11/13 HTC 3.3V, 10Mbps Half-Duplex RS-485/RS-422 Transceivers MAX3485 APPLICATION INFORMATION Functional Description The MAX3485 is 3.3V low power half-duplex differential transceiver that meets the requirements of RS-485 and RS-422. The RS-485 Standard is ideal for multi-drop applications and for long-distance interfaces. RS-485 allows up to 32 drivers and 32 receivers to be connected to a data bus, making it an ideal choice for multi-drop applications. Since the cabling can be as long as 4,000 feet, RS-485 transceivers are equipped with a wide common mode range of −7V to 12V to accommodate ground potential differences. Because RS-485 is a differential interface, data is virtually immune to noise in the transmission line. Output Enable The receiver output RO is enabled when ���� RE is low. RO is high impedance when ���� RE is high. The driver outputs are enabled by bringing DE high. They are high impedance when DE is low. If the driver outputs are enabled, the parts function as line drivers. While they are high impedance, they function as line receivers if ���� RE is low. Driver The driver outputs of the MAX3485 are differential 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 worst case loading of 54Ω across the differential outputs, the driver can maintain greater than 1.5V levels. The driver of the MAX3485 has an enable control line which is active high. A logic high on DE (pin 3) will enable the differential driver outputs. A logic low on DE (pin 3) will tri-state the driver outputs. The transmitter of the MAX3485 will operate up to 10Mbps. Receiver The MAX3485 receiver has differential inputs with an input sensitivity as low as ±200mV. Input impedance of the receiver is typically 15kΩ (12kΩ minimum). A wide common mode range of −7V to +12V allows for large ground potential differences between systems. The receiver of the MAX3485 has a tri-state enable control pin. A logic low on ���� RE (pin 2) will enable the receiver, a logic high on ���� RE (pin 2) will disable the receiver. The receiver for the MAX3485 will operate up to 10Mbps. The receiver is equipped with the fail-safe feature. Fail-safe feature guarantees that the receiver output will be in a high state when the input is left unconnected. Apr. 2020 – R1.0 12/13 HTC 3.3V, 10Mbps Half-Duplex RS-485/RS-422 Transceivers MAX3485 REVISION NOTICE The description in this data sheet is subject to change without any notice to describe its electrical characteristics properly. Apr. 2020 – R1.0 13/13 HTC