MAX485中文手册.pdf

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19-0122; Rev 8; 10/03 海纳电子资讯网： www.fpga-arm.com _______________________________ 概述 MAX481、MAX483、MAX485、MAX487-MAX491以及 MAX1487是用于RS-485与RS-422通信的低功耗收发器，每个器件中都具有一个驱动器和一个接收器。MAX483、 MAX487、MAX488以及MAX489具有限摆率驱动器，可以减小EMI，并降低由不恰当的终端匹配电缆引起的反射，实现最高 2 5 0 k b p s 的无差错数据传输。 M A X 4 8 1 、 MAX485、MAX490、MAX491、MAX1487的驱动器摆率不受限制，可以实现最高2.5Mbps的传输速率。这些收发器在驱动器禁用的空载或满载状态下，吸取的电源电流在 1 2 0 ( A 至 5 0 0 ( A 之间。另外， M A X 4 8 1 、 MAX483 与 MAX487 具有低电流关断模式，仅消耗 0.1µA。所有器件都工作在5V单电源下。驱动器具有短路电流限制，并可以通过热关断电路将驱动器输出置为高阻状态，防止过度的功率损耗。接收器输入具有失效保护特性，当输入开路时，可以确保逻辑高电平输出。 MAX487与MAX1487具有四分之一单位负载的接收器输入阻抗，使得总线上最多可以有 1 2 8 个 M A X 4 8 7 / MAX1487收发器。使用MAX488-MAX491可以实现全双工通信，而MAX481、MAX483、MAX485、MAX487与 MAX1487则为半双工应用设计。 _______________________________ 应用低功耗RS-485收发器低功耗RS-422收发器电平转换器用于EMI敏感应用的收发器工业控制局域网低功耗、限摆率、 RS-485/RS-422收发器 ____________________ 下一代器件的特性 ♦ 容错应用 MAX3430: ±80V故障保护、失效保护、1/4单位负载、+3.3V、RS-485收发器 MAX3440E-MAX3444E: ±15kV ESD保护、±60V 故障保护、10Mbps、失效保护、 RS-485/J1708收发器 ♦ 对于空间受限应用 MAX3460-MAX3464: +5V、失效保护、20Mbps、 Profibus RS-485/RS-422收发器 MAX3362: +3.3V、高速、RS-485/RS-422收发器，采用SOT23封装 MAX3280E-MAX3284E: ±15kV ESD保护、 52Mbps、+3V至+5.5V、SOT23、 RS-485/RS-422、真失效保护接收器 MAX3293/MAX3294/MAX3295: 20Mbps、+3.3V、 SOT23、RS-485/RS-422发送器 ♦ 对于多通道收发器应用 MAX3030E-MAX3033E: ±15kV ESD保护、 +3.3V、四路RS-422发送器 ♦ 对于失效保护应用 MAX3080-MAX3089: 失效保护、高速(10Mbps)、限摆率RS-485/RS-422收发器 ♦ 对于低电压应用 MAX3483E/MAX3485E/MAX3486E/MAX3488E/ MAX3490E/MAX3491E: +3.3V供电、±15kV ESD 保护、12Mbps、限摆率、真正的RS-485/RS-422 收发器定购信息在本资料的最后给出。 / / M A X 4 8 1 M A X 4 8 3 M A X 4 8 5 M A X 4 8 7 – M A X 4 9 1 M A X 1 4 8 7 / / _____________________________________________________________________ 选择表 PART NUMBER HALF/FULL DUPLEX DATA RATE (Mbps) SLEW-RATE LIMITED LOW-POWER SHUTDOWN RECEIVER/ DRIVER ENABLE QUIESCENT CURRENT (µA) MAX481 MAX483 MAX485 MAX487 MAX488 MAX489 MAX490 MAX491 MAX1487 Half Half Half Half Full Full Full Full Half 2.5 0.25 2.5 0.25 0.25 0.25 2.5 2.5 2.5 No Yes No Yes Yes Yes No No No Yes Yes No Yes No No No No No Yes Yes Yes Yes No Yes No Yes Yes 300 120 300 120 120 120 300 300 230 NUMBER OF TRANSMITTERS ON BUS 32 32 32 128 32 32 32 32 128 PIN COUNT 8 8 8 8 8 14 8 14 8 ________________________________________________________________ Maxim Integrated Products 1 本文是 Maxim正式英文资料的译文，Maxim不对翻译中存在的差异或由此产生的错误负责。请注意译文中可能存在文字组织或翻译错误，如需确认任何词语的准确性，请参考 Maxim提供的英文版资料。索取免费样品和最新版的数据资料，请访问 Maxim的主页：www.maxim-ic.com.cn。

海纳电子资讯网： www.fpga-arm.com 低功耗、限摆率、 RS-485/RS-422收发器 ABSOLUTE MAXIMUM RATINGS Supply Voltage (VCC).............................................................12V Control Input Voltage (RE, DE)...................-0.5V to (VCC + 0.5V) Driver Input Voltage (DI).............................-0.5V to (VCC + 0.5V) Driver Output Voltage (A, B)...................................-8V to +12.5V Receiver Input Voltage (A, B).................................-8V to +12.5V Receiver Output Voltage (RO).....................-0.5V to (VCC +0.5V) Continuous Power Dissipation (TA = +70°C) 14-Pin SO (derate 8.33mW/°C above +70°C)...............667mW 8-Pin µMAX (derate 4.1mW/°C above +70°C) ..............830mW 8-Pin CERDIP (derate 8.00mW/°C above +70°C).........640mW 14-Pin CERDIP (derate 9.09mW/°C above +70°C).......727mW Operating Temperature Ranges 8-Pin Plastic DIP (derate 9.09mW/°C above +70°C) ....727mW 14-Pin Plastic DIP (derate 10.00mW/°C above +70°C) ..800mW 8-Pin SO (derate 5.88mW/°C above +70°C).................471mW MAX4_ _C_ _/MAX1487C_ A ...............................0°C to +70°C MAX4_ _E_ _/MAX1487E_ A.............................-40°C to +85°C MAX4_ _MJ_/MAX1487MJA ...........................-55°C to +125°C Storage Temperature Range .............................-65°C to +160°C Lead Temperature (soldering, 10sec) .............................+300°C 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 in the operational sections of the specifications is not implied. Exposure to absolute maximum rating conditions for extended periods may affect device reliability. DC ELECTRICAL CHARACTERISTICS (VCC = 5V ±5%, TA = TMIN to TMAX, unless otherwise noted.) (Notes 1, 2) PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS Differential Driver Output (no load) Differential Driver Output (with load) Change in Magnitude of Driver Differential Output Voltage for Complementary Output States Driver Common-Mode Output Voltage Change in Magnitude of Driver Common-Mode Output Voltage for Complementary Output States Input High Voltage Input Low Voltage Input Current Input Current (A, B) Receiver Differential Threshold Voltage Receiver Input Hysteresis Receiver Output High Voltage Receiver Output Low Voltage Three-State (high impedance) Output Current at Receiver VOD1 VOD2 R = 50Ω (RS-422) R = 27Ω (RS-485), Figure 4 ∆VOD R = 27Ω or 50Ω, Figure 4 VOC R = 27Ω or 50Ω, Figure 4 ∆VOD R = 27Ω or 50Ω, Figure 4 VIH VIL IIN1 IIN2 VTH ∆VTH VOH VOL IOZR DE, DI, RE DE, DI, RE DE, DI, RE DE = 0V; VCC = 0V or 5.25V, all devices except MAX487/MAX1487 MAX487/MAX1487, DE = 0V, VCC = 0V or 5.25V -7V ≤ VCM ≤ 12V VCM = 0V IO = -4mA, VID = 200mV IO = 4mA, VID = -200mV 0.4V ≤ VO ≤ 2.4V VIN = 12V VIN = -7V VIN = 12V VIN = -7V Receiver Input Resistance RIN -7V ≤ VCM ≤ 12V, all devices except MAX487/MAX1487 -7V ≤ VCM ≤ 12V, MAX487/MAX1487 2 1.5 2.0 -0.2 3.5 12 48 70 5 5 0.2 3 0.2 0.8 ±2 1.0 -0.8 0.25 -0.2 0.2 0.4 ±1 V V V V V V V µA mA mA V mV V V µA kΩ kΩ 2 _______________________________________________________________________________________ / 7 8 4 1 X A M 1 9 4 X A M – 7 8 4 X A M 5 8 4 X A M 3 8 4 X A M 1 8 4 X A M / / /

海纳电子资讯网： www.fpga-arm.com 低功耗、限摆率、 RS-485/RS-422收发器 MAX UNITS DC ELECTRICAL CHARACTERISTICS (continued) (VCC = 5V ±5%, TA = TMIN to TMAX, unless otherwise noted.) (Notes 1, 2) PARAMETER SYMBOL CONDITIONS MIN No-Load Supply Current (Note 3) ICC MAX488/MAX489, DE, DI, RE = 0V or VCC MAX490/MAX491, DE, DI, RE = 0V or VCC MAX481/MAX485, RE = 0V or VCC MAX1487, RE = 0V or VCC MAX483/MAX487, RE = 0V or VCC DE = VCC DE = 0V DE = VCC DE = 0V DE = 5V DE = 0V MAX483 MAX487 Supply Current in Shutdown Driver Short-Circuit Current, VO = High Driver Short-Circuit Current, VO = Low Receiver Short-Circuit Current ISHDN IOSD1 IOSD2 IOSR MAX481/483/487, DE = 0V, RE = VCC -7V ≤ VO ≤12V (Note 4) -7V ≤ VO ≤12V (Note 4) 0V ≤ VO ≤ VCC 35 35 7 TYP 120 300 500 300 300 230 350 250 120 0.1 250 500 900 500 500 400 650 400 250 10 250 250 95 SWITCHING CHARACTERISTICS—MAX481/MAX485, MAX490/MAX491, MAX1487 (VCC = 5V ±5%, TA = TMIN to TMAX, unless otherwise noted.) (Notes 1, 2) PARAMETER SYMBOL Driver Input to Output Driver Output Skew to Output Driver Rise or Fall Time Driver Enable to Output High Driver Enable to Output Low Driver Disable Time from Low Driver Disable Time from High tPLH tPHL tSKEW tR, tF tZH tZL tLZ tHZ Receiver Input to Output tPLH, tPHL | tPLH - tPHL | Differential Receiver Skew Receiver Enable to Output Low Receiver Enable to Output High Receiver Disable Time from Low Receiver Disable Time from High Maximum Data Rate Time to Shutdown tSKD tZL tZH tLZ tHZ fMAX tSHDN CONDITIONS Figures 6 and 8, RDIFF = 54Ω, CL1 = CL2 = 100pF Figures 6 and 8, RDIFF = 54Ω, CL1 = CL2 = 100pF MAX481, MAX485, MAX1487 Figures 6 and 8, RDIFF = 54Ω, MAX490C/E, MAX491C/E CL1 = CL2 = 100pF MAX490M, MAX491M Figures 7 and 9, CL = 100pF, S2 closed Figures 7 and 9, CL = 100pF, S1 closed Figures 7 and 9, CL = 15pF, S1 closed Figures 7 and 9, CL = 15pF, S2 closed Figures 6 and 10, RDIFF = 54Ω, CL1 = CL2 = 100pF Figures 6 and 10, RDIFF = 54Ω, CL1 = CL2 = 100pF Figures 5 and 11, CRL = 15pF, S1 closed Figures 5 and 11, CRL = 15pF, S2 closed Figures 5 and 11, CRL = 15pF, S1 closed Figures 5 and 11, CRL = 15pF, S2 closed MAX481, MAX485, MAX1487 MAX490C/E, MAX491C/E MAX490M, MAX491M MAX481 (Note 5) MIN 10 10 3 5 3 20 20 20 2.5 50 TYP 30 30 5 15 15 15 40 40 40 40 90 90 90 13 20 20 20 20 MAX 60 60 10 40 25 40 70 70 70 70 200 150 200 50 50 50 50 200 600 Mbps ns _______________________________________________________________________________________ 3 / / / M A X 4 8 1 M A X 4 8 3 M A X 4 8 5 M A X 4 8 7 – M A X 4 9 1 M A X 1 4 8 7 / µA µA mA mA mA UNITS ns ns ns ns ns ns ns ns ns ns ns ns ns

海纳电子资讯网： www.fpga-arm.com 低功耗、限摆率、 RS-485/RS-422收发器 SWITCHING CHARACTERISTICS—MAX481/MAX485, MAX490/MAX491, MAX1487 (continued) (VCC = 5V ±5%, TA = TMIN to TMAX, unless otherwise noted.) (Notes 1, 2) PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS Driver Enable from Shutdown to Output High (MAX481) Driver Enable from Shutdown to Output Low (MAX481) tZH(SHDN) Figures 7 and 9, CL = 100pF, S2 closed tZL(SHDN) Figures 7 and 9, CL = 100pF, S1 closed Receiver Enable from Shutdown to Output High (MAX481) tZH(SHDN) Figures 5 and 11, CL = 15pF, S2 closed, A - B = 2V Receiver Enable from Shutdown to Output Low (MAX481) tZL(SHDN) Figures 5 and 11, CL = 15pF, S1 closed, B - A = 2V 40 40 100 100 300 1000 300 1000 ns ns ns ns SWITCHING CHARACTERISTICS—MAX483, MAX487/MAX488/MAX489 (VCC = 5V ±5%, TA = TMIN to TMAX, unless otherwise noted.) (Notes 1, 2) PARAMETER SYMBOL Driver Input to Output Driver Output Skew to Output Driver Rise or Fall Time Driver Enable to Output High Driver Enable to Output Low Driver Disable Time from Low Driver Disable Time from High Receiver Input to Output I tPLH - tPHL I Differential Receiver Skew Receiver Enable to Output Low Receiver Enable to Output High Receiver Disable Time from Low Receiver Disable Time from High Maximum Data Rate Time to Shutdown Driver Enable from Shutdown to Output High Driver Enable from Shutdown to Output Low Receiver Enable from Shutdown to Output High Receiver Enable from Shutdown to Output Low tPLH tPHL tSKEW tR, tF tZH tZL tLZ tHZ tPLH tPHL tSKD tZL tZH tLZ tHZ fMAX tSHDN tZH(SHDN) tZL(SHDN) tZH(SHDN) tZL(SHDN) CONDITIONS Figures 6 and 8, RDIFF = 54Ω, CL1 = CL2 = 100pF Figures 6 and 8, RDIFF = 54Ω, CL1 = CL2 = 100pF Figures 6 and 8, RDIFF = 54Ω, CL1 = CL2 = 100pF Figures 7 and 9, CL = 100pF, S2 closed Figures 7 and 9, CL = 100pF, S1 closed Figures 7 and 9, CL = 15pF, S1 closed Figures 7 and 9, CL = 15pF, S2 closed Figures 6 and 10, RDIFF = 54Ω, CL1 = CL2 = 100pF Figures 6 and 10, RDIFF = 54Ω, CL1 = CL2 = 100pF Figures 5 and 11, CRL = 15pF, S1 closed Figures 5 and 11, CRL = 15pF, S2 closed Figures 5 and 11, CRL = 15pF, S1 closed Figures 5 and 11, CRL = 15pF, S2 closed tPLH, tPHL < 50% of data period MAX483/MAX487 (Note 5) MAX483/MAX487, Figures 7 and 9, CL = 100pF, S2 closed MAX483/MAX487, Figures 7 and 9, CL = 100pF, S1 closed MAX483/MAX487, Figures 5 and 11, CL = 15pF, S2 closed MAX483/MAX487, Figures 5 and 11, CL = 15pF, S1 closed MIN 250 250 250 250 250 300 300 250 250 250 50 TYP 800 800 100 100 20 20 20 20 200 MAX 2000 2000 800 2000 2000 2000 3000 3000 2000 2000 50 50 50 50 600 2000 2000 2500 2500 UNITS ns ns ns ns ns ns ns ns ns ns ns ns ns kbps ns ns ns ns ns 4 _______________________________________________________________________________________ / 7 8 4 1 X A M 1 9 4 X A M – 7 8 4 X A M 5 8 4 X A M 3 8 4 X A M 1 8 4 X A M / / /

海纳电子资讯网： www.fpga-arm.com 低功耗、限摆率、 RS-485/RS-422收发器 NOTES FOR ELECTRICAL/SWITCHING CHARACTERISTICS Note 1: All currents into device pins are positive; all currents out of device pins are negative. All voltages are referenced to device ground unless otherwise specified. Note 2: All typical specifications are given for VCC = 5V and TA = +25°C. Note 3: Supply current specification is valid for loaded transmitters when DE = 0V. Note 4: Applies to peak current. See Typical Operating Characteristics. Note 5: The MAX481/MAX483/MAX487 are put into shutdown by bringing RE high and DE low. If the inputs are in this state for less than 50ns, the parts are guaranteed not to enter shutdown. If the inputs are in this state for at least 600ns, the parts are guaranteed to have entered shutdown. See Low-Power Shutdown Mode section. _______________________________________________________________ 典型工作特性 (VCC = 5V, TA = +25°C, unless otherwise noted.) OUTPUT CURRENT vs. RECEIVER OUTPUT LOW VOLTAGE OUTPUT CURRENT vs. RECEIVER OUTPUT HIGH VOLTAGE RECEIVER OUTPUT HIGH VOLTAGE vs. TEMPERATURE ) A m ( T N E R R U C T U P T U O ) V ( E G A T L O V W O L T U P T U O 45 40 35 30 25 20 15 10 5 0 0.9 0.8 0.7 0.6 0.5 0.4 0.3 0.2 0.1 0 1 0 - 1 8 4 X A M ) A m ( T N E R R U C T U P T U O -20 -18 -16 -14 -12 -10 -8 -6 -4 -2 0 2 0 - 1 8 4 X A M ) V ( E G A T L O V H G H T U P T U O I IRO = 8mA 3 0 - 1 8 4 X A M 4.8 4.6 4.4 4.2 4.0 3.8 3.6 3.4 3.2 3.0 0 1.0 0.5 2.0 OUTPUT LOW VOLTAGE (V) 1.5 2.5 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0 -50 -25 OUTPUT HIGH VOLTAGE (V) 25 75 0 TEMPERATURE (°C) 50 100 125 RECEIVER OUTPUT LOW VOLTAGE vs. TEMPERATURE DRIVER OUTPUT CURRENT vs. DIFFERENTIAL OUTPUT VOLTAGE DRIVER DIFFERENTIAL OUTPUT VOLTAGE vs. TEMPERATURE IRO = 8mA 4 0 - 1 8 4 X A M -50 -25 25 75 0 TEMPERATURE (°C) 50 100 125 ) A m ( T N E R R U C T U P T U O 90 80 70 60 50 40 30 20 10 0 0 5 0 - 1 8 4 X A M ) V ( E G A T L O V T U P T U O L A I T N E R E F F I D 4.5 1.5 1.0 4.0 0.5 DIFFERENTIAL OUTPUT VOLTAGE (V) 2.5 3.0 2.0 3.5 2.4 2.3 2.2 2.1 2.0 1.9 1.8 1.7 1.6 1.5 -50 -25 R = 54Ω 6 0 - 1 8 4 X A M 25 0 75 TEMPERATURE (°C) 50 100 125 _______________________________________________________________________________________ 5 / / / M A X 4 8 1 M A X 4 8 3 M A X 4 8 5 M A X 4 8 7 – M A X 4 9 1 M A X 1 4 8 7 /

海纳电子资讯网： www.fpga-arm.com 低功耗、限摆率、 RS-485/RS-422收发器 __________________________________________________________ 典型工作特性（续） (VCC = 5V, TA = +25°C, unless otherwise noted.) ) A m ( T N E R R U C T U P T U O 140 120 100 80 60 40 20 0 OUTPUT CURRENT vs. DRIVER OUTPUT LOW VOLTAGE OUTPUT CURRENT vs. DRIVER OUTPUT HIGH VOLTAGE 7 0 - 1 8 4 X A M ) A m ( T N E R R U C T U P T U O -120 -100 -80 -60 -40 -20 0 MAX481/MAX485/MAX490/MAX491 SUPPLY CURRENT vs. TEMPERATURE MAX481/MAX485; DE = VCC, RE = X 1 1 - 1 8 4 X A M MAX485; DE = 0, RE = X, MAX481; DE = RE = 0 MAX490/MAX491; DE = RE = X MAX481; DE = 0, RE = VCC 8 0 - 1 8 4 X A M ) A µ ( T N E R R U C Y L P P U S 600 500 400 300 200 100 0 0 2 4 6 8 10 12 -7 -6 -5 -4 -3 -2 -1 0 1 2 3 4 5 -50 -25 OUTPUT LOW VOLTAGE (V) OUTPUT HIGH VOLTAGE (V) 25 75 0 TEMPERATURE (°C) 50 100 125 ) A µ ( T N E R R U C Y L P P U S 600 500 400 300 200 100 0 MAX483/MAX487–MAX489 SUPPLY CURRENT vs. TEMPERATURE 2 1 - 1 8 4 X A M MAX483; DE = VCC, RE = X MAX487; DE = VCC, RE = X MAX483/MAX487; DE = RE = 0, MAX488/MAX489; DE = RE = X MAX483/MAX487; DE = 0, RE = VCC ) A µ ( T N E R R U C Y L P P U S 600 500 400 300 200 100 0 MAX1487 SUPPLY CURRENT vs. TEMPERATURE 3 1 - 1 8 4 X A M MAX1487; DE = VCC, RE = X MAX1487; DE = 0V, RE = X -50 -25 25 75 0 TEMPERATURE (°C) 50 100 125 -60 -40 -20 40 20 60 80 0 TEMPERATURE (°C) 100 120 140 / 7 8 4 1 X A M 1 9 4 X A M – 7 8 4 X A M 5 8 4 X A M 3 8 4 X A M 1 8 4 X A M / / / 6 _______________________________________________________________________________________

海纳电子资讯网： www.fpga-arm.com 低功耗、限摆率、 RS-485/RS-422收发器 ___________________________________________________________________ 引脚说明 PIN 引脚 MAX481/MAX483/ MAX485/MAX487/ MAX1487 MAX488/ MAX490 MAX489/ MAX491 NAME NAME 名称 DIP/SO µMAX DIP/SO µMAX DIP/SO FUNCTION FUNCTION 功能 3 4 5 6 7 — — 8 — 1 — 2 — 1 2 3 4 5 — — 6 — 7 — 8 — TOP VIEW 2 — — 3 4 5 6 — 8 — 7 1 — 4 — — 5 6 7 8 — 2 — 1 3 — 2 3 4 5 RO RE DE DI Receiver Output: If A > B by 200mV, RO will be high; 接收器输出：若A > B 200mV，则RO为高电平； If A < B by 200mV, RO will be low. 若A < B 200mV，则RO为低电平。 Receiver Output Enable. RO is enabled when RE is low; RO is 接收器输出使能。当RE为低电平时，RO有效； high impedance when RE is high. 当RE为高电平时，RO为高阻状态。 Driver Output Enable. The driver outputs, Y and Z, are enabled 驱动器输出使能。DE变为高电平时，驱动器输出Y与Z有效； by bringing DE high. They are high impedance when DE is low. If 当DE为低电平时，驱动器输出为高阻状态。 the driver outputs are enabled, the parts function as line drivers. 当驱动器输出有效时，器件被用作线驱动器。而高阻状态下， While they are high impedance, they function as line receivers if 若RE为低电平，则器件被用作线接收器。 RE is low. Driver Input. A low on DI forces output Y low and output Z high. 驱动器输入。DI上的低电平强制输出Y为低电平，而输出Z为高电平。 Similarly, a high on DI forces output Y high and output Z low. 同理，DI上的高电平强制输出Y为高电平，而输出Z为低电平。 6, 7 GND Ground 地 9 10 — 12 — 11 14 1, 8, 13 Y Z A A B B VCC N.C. Noninverting Driver Output 驱动器同相输出端 Inverting Driver Output 驱动器反相输出端 Noninverting Receiver Input and Noninverting Driver Output 接收器同相输入端和驱动器同相输出端 Noninverting Receiver Input 接收器同相输入端 Inverting Receiver Input and Inverting Driver Output 接收器反相输入端和驱动器反相输出端 Inverting Receiver Input 接收器反相输入端 Positive Supply: 4.75V ≤ VCC ≤ 5.25V 正电源：4.75V ≤ VCC ≤ 5.25V No Connect—not internally connected 未连接——内部未连接 RO RE DE DI B VCC RO RE 1 2 3 4 1 2 3 4 R D DIP/SO MAX481 MAX483 MAX485 MAX487 MAX1487 µMAX 8 7 6 5 8 7 6 5 VCC B A GND A GND DI DE RO RE DE DI 1 2 3 4 R D 8 7 6 5 B VCC Rt A GND MAX481 MAX483 MAX485 MAX487 MAX1487 Rt B A DE D R RE DI RO NOTE: PIN LABELS Y AND Z ON TIMING, TEST, AND WAVEFORM DIAGRAMS REFER TO PINS A AND B WHEN DE IS HIGH. TYPICAL OPERATING CIRCUIT SHOWN WITH DIP/SO PACKAGE. 图1. MAX481/MAX483/MAX485/MAX487/MAX1487引脚配置与典型工作电路 _______________________________________________________________________________________ 7 / / / M A X 4 8 1 M A X 4 8 3 M A X 4 8 5 M A X 4 8 7 – M A X 4 9 1 M A X 1 4 8 7 /

海纳电子资讯网： www.fpga-arm.com 低功耗、限摆率、 RS-485/RS-422收发器 / 7 8 4 1 X A M 1 9 4 X A M – 7 8 4 X A M 5 8 4 X A M 3 8 4 X A M 1 8 4 X A M / / / TOP VIEW VCC RO DI GND B A VCC RO 1 2 3 4 1 2 3 4 R D DIP/SO MAX488 MAX490 µMAX 8 7 6 5 8 7 6 5 A B Z Y Z Y GND DI 图2. MAX488/MAX490引脚配置与典型工作电路 TOP VIEW N.C. RO RE DE DI GND GND 1 2 3 4 5 6 7 R D DIP/SO 14 13 12 11 10 9 8 VCC N.C. A B Z Y N.C. 5 2 1, 8, 13 DI RO NC 3 2 DI RO VCC 1 D R 4 GND 5 6 8 7 Y Z A B Rt MAX488 MAX490 Rt R VCC D GND NOTE: TYPICAL OPERATING CIRCUIT SHOWN WITH DIP/SO PACKAGE. DE 4 VCC 14 D R 9 10 12 11 Y Z A B Rt 3 6, 7 RE GND MAX489 MAX491 VCC RE Rt R D GND DE RO DI RO DI 图3. MAX489/MAX491引脚配置与典型工作电路 ____________________________ 应用说明 MAX481/MAX483/MAX485/MAX487-MAX491 以及 MAX1487是用于RS-485与RS-422通信的低功耗收发器。 MAX481、MAX485、MAX490、MAX491以及MAX1487 能够以最高 2.5Mbps 的数据速率发送并接收数据；而 MAX483、MAX487、MAX488以及MAX489则用于最高 250kbps 的数据速率。MAX488-MAX491 是全双工收发器，MAX481、MAX483、MAX485、MAX487 以及 MAX1487是半双工收发器。另外，MAX481、MAX483、 MAX485、MAX487、MAX489、MAX491以及MAX1487 中包含驱动器使能(DE)与接收器使能(RE)控制引脚，被禁用时，驱动器或接收器输出为高阻态。 MAX487/MAX1487: 总线上可以接128个收发器与标准 RS-485 驱动器 ( 最多 32 个收发器 ) 的单位负载 ( 12kΩ输入阻抗 ) 相比，MAX487与MAX1487具有48kΩ 输入电阻，1/4单位负载的接收器输入阻抗，在一条总线上允许最多挂接128个收发器。MAX487/MAX1487与其他 RS-485收发器的任意组合可以允许32个收发器或更少的收发器连接在同一条总线上。MAX481/MAX483/MAX485 与MAX488-MAX491具有标准的12 kΩ接收器输入阻抗。 8 _______________________________________________________________________________________

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