MAX485中文资料
MAX485中文资料
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_______________________________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250k b p s 的无差错数据传输。
M A X 481、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120(A 至500(A 之间。
另外，MAX481、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128个M A X 487/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____________________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MAX481/MAX483/MAX485/MAX487–MAX491/MAX1487低功耗、限摆率、RS-485/RS-422收发器_____________________________________________________________________选择表19-0122; Rev 8; 10/03定购信息在本资料的最后给出。
双路SPDT 音频开关MAX4855
MAX4855
0.75Ω、双路 SPDT 音频开关， 具有集成比较器
ABSOLUTE MAXIMUM RATINGS
VCC, IN_, CIN_ to GND ..............................................-0.3V to +6.0V NO_, NC_, COM_, COUT_ (Note 1) ...............-0.3V to (VCC + 0.3V) COUT_ Continuous Current ..................................................±20mA Closed Switch Continuous Current COM_, NO_, NC_.......±300mA Peak Current COM_, NO_, NC_
TA = +25°C TA = -40°C to +85°C
0.18 0.275 Ω
0.3
NO_/NC_ Off-Leakage Current (Note 2)
VCC = 5.5V, VNC_ or VNO_ = TA = +25°C
-2
IOFF 1V or 4.5V, VCOM_ = 4.5V or
(VCC = +2.7V to +5.5V, TA = -40°C to +85°C, unless otherwise noted. Typical values are at VCC = +3.0V, TA = +25°C, unless otherwise noted.) (Note 2)
PARAMETER Turn-Off Time
MAX485中文数据手册资料
MAX485中文资料2009-11-28 14:49MAX485中文资料，MAX485 PDF,DATASHEET,电路图，通讯程序内容介绍：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250kbps 的无差错数据传输。
MAX481、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120(A 至500(A 之间。
另外，MAX481、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。
MAX481,MAX483,MAX485,MAX487,MAX1487引脚（管脚）图及工作电路MAX485通讯程序与MAX232通讯程序在本质上是一样的，只是MAX485通讯程序需要加上通讯方向控制。
下面是基于mega128 16AU的485通信中断接收的程序，调试通过,晶振为外部16M,MAX485的DE和RE短接连PC0口，程序如下：#define SEND_485 PORTC|=0x01#define READ_485 PORTC&=0xfevoid Usart1_init(void) //16Mhz频率，设置波特率9.6k，8位数据位，无校验，接收发送使能，1位停止位{UBRR1H=0;UBRR1L=103;UCSR1B=(1<<RXCIE1)|(1<<RXEN1)|(1<<TXEN1); //发送接收使能，使用中断方式，UCSR1C=(1<<UCSZ10)|(1<<UCSZ11); //0x06 8位数据，1位停止位，无校验}void Usart1_transmit(unsigned char c) //查询方式发送接收字符函数{SEND_485;DelayBus();DelayBus();DelayBus();while( !(UCSR1A&(1<<UDRE1)));//等待发送缓冲区为空UDR1=c;while(!(UCSR1A&(1<<TXC1)));// UDCR0=c;UCSR1A |= _BV(TXC1);//将发送结束标志位清零// SET_BIT(UCSR1A,);READ_485;direction++;}SIGNAL(SIG_UART1_RECV)//serial port 1 {if(UCSR1A&(1<<RXC1)){rec1buff=UDR1;rec1_flag=1;。
MAX485EEPA+中文资料
14-Pin Plastic DIP (derate 10.00mW/°C above +70°C) ..800mW 8-Pin SO (derate 5.88mW/°C above +70°C).................471mW 14-Pin SO (derate 8.33mW/°C above +70°C)...............667mW Operating Temperature Ranges MAX4_ _C_ _/MAX1487EC_ A .............................0°C to +70°C MAX4_ _E_ _/MAX1487EE_ A...........................-40°C to +85°C StorageБайду номын сангаасTemperature Range .............................-65°C to +160°C Lead Temperature (soldering, 10sec) .............................+300°C
Receiver Output Voltage (RO)....................-0.5V to (VCC + 0.5V)
Continuous Power Dissipation (TA = +70°C)
8-Pin Plastic DIP (derate 9.09mW/°C above +70°C) ....727mW
Ordering Information
PART MAX481ECPA MAX481ECSA MAX481EEPA MAX481EESA MAX483ECPA MAX483ECSA MAX483EEPA MAX483EESA
MAX485ECPA中文资料
MAX481E/MAX483E/MAX485E/MAX487E–MAX491E/MAX1487E
19-0410; Rev 3; 7/96
±15kV ESD-Protected, Slew-Rate-Limited, Low-Power, RS-485/RS-422 Transceivers
±15kV ESD-Protected, Slew-Rate-Limited, Low-Power, RS-485/RS-422 Transceivers
ABSOLUTE MAXIMUM RATINGS
Supply Control
Voltage (VCC) Input Voltage
.(.–R—..E.–..,..D..E..)........................................-.0....5..V...t.o...(.V..C...C...+...0...152VV)
Drivers are short-circuit current limited, and are protected against excessive power dissipation by thermal shutdown circuitry that places their 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.
14-Pin Plastic DIP (derate 10.00mW/°C above +70°C) ..800mW 8-Pin SO (derate 5.88mW/°C above +70°C).................471mW 14-Pin SO (derate 8.33mW/°C above +70°C)...............667mW Operating Temperature Ranges MAX4_ _C_ _/MAX1487EC_ A .............................0°C to +70°C MAX4_ _E_ _/MAX1487EE_ A...........................-40°C to +85°C Storage Temperature Range .............................-65°C to +160°C Lead Temperature (soldering, 10sec) .............................+300°C
max485芯片
max485芯片MAX485是一种用于串行通讯的芯片，它可以实现半双工的通信，常用于RS-485网络中。
这款芯片具有低功耗、高速率、低电压、可靠性高等特点，被广泛应用于工业自动化、远程监控、数据采集等领域。
MAX485芯片采用了双绞四线制接口，可以实现长距离传输，通信距离可达1200米。
其通信速率可以高达2.5Mbps，同时还支持多点连接，可以连接最多32个驱动器和接收器。
MAX485芯片的工作电压范围为3.0V至5.25V，因此可以适应不同的工作环境。
在低功耗模式下，它的供电电流仅为1μA，非常适合电池供电的应用。
此外，MAX485还具有过温保护功能，可以保护芯片免受过热损坏。
MAX485芯片的架构采用了低功耗CMOS技术，具有自动接收释放和禁用保护电路，可以有效地降低功耗。
此外，它还配备了过电流保护和过电压保护电路，可以保护芯片免受电路故障的影响。
MAX485芯片的引脚功能如下：- A/B：差分传输线，用于发送和接收数据。
- RE/DE：接收使能/发送使能引脚，用于控制芯片的发送和接收功能。
- RO/RE：发送使能/接收使能引脚，用于选择芯片的发送和接收功能。
- VCC：供电引脚，具有3.0V至5.25V的宽工作电压范围。
- GND：地线引脚，用于接地连接。
MAX485芯片的工作原理如下：- 发送数据时，通过RE/DE引脚将芯片设置为发送模式，将发送的数据信号输入到A/B差分传输线上。
- 接收数据时，通过RE/DE引脚将芯片设置为接收模式，通过RO/RE引脚选择芯片的发送和接收功能。
接收到的数据信号经过差分收发线转换为通用串行总线信号。
- 在半双工通信时，A/B线上只能有一方发送数据，另一方只能接收数据。
总之，MAX485芯片是一款功能强大且灵活的串行通信芯片，具有高速率、低功耗、可靠性高等特点，被广泛应用于工业自动化、远程监控、数据采集等领域。
它的性能优越和稳定性使得它成为RS-485通信领域中的首选芯片。
MAX485ECPA中文资料
General DescriptionThe MAX481E, MAX483E, MAX485E, MAX487E–MAX491E, and MAX1487E are low-power transceivers for RS-485 and RS-422 communications in harsh environ-ments. Each driver output and receiver input is protected against ±15kV electro-static discharge (ESD) shocks,without latchup. These parts contain one driver and one receiver. The MAX483E, MAX487E, MAX488E, and MAX489E feature reduced slew-rate drivers that minimize EMI and reduce reflections caused by improperly termi-nated cables, thus allowing error-free data transmission up to 250kbps. The driver slew rates of the MAX481E,MAX485E, MAX490E, MAX491E, and MAX1487E are not limited, allowing them to transmit up to 2.5Mbps.These transceivers draw as little as 120µA supply cur-rent when unloaded or when fully loaded with disabled drivers (see Selector Guide ). Additionally, the MAX481E,MAX483E, and MAX487E have a low-current shutdown mode in which they consume only 0.5µA. All parts oper-ate from a single +5V supply.Drivers are short-circuit current limited, and are protected against excessive power dissipation by thermal shutdown circuitry that places their outputs into a high-impedance state. The receiver input has a fail-safe feature that guar-antees a logic-high output if the input is open circuit.The MAX487E and MAX1487E feature quarter-unit-load receiver input impedance, allowing up to 128 trans-ceivers on the bus. The MAX488E–MAX491E are designed for full-duplex communications, while the MAX481E, MAX483E, MAX485E, MAX487E, and MAX1487E are designed for half-duplex applications.For applications that are not ESD sensitive see the pin-and function-compatible MAX481, MAX483, MAX485,MAX487–MAX491, and MAX1487.ApplicationsLow-Power RS-485 Transceivers Low-Power RS-422 Transceivers Level TranslatorsTransceivers for EMI-Sensitive Applications Industrial-Control Local Area NetworksNext-Generation Device Features♦For Fault-Tolerant Applications:MAX3430: ±80V Fault-Protected, Fail-Safe, 1/4-Unit Load, +3.3V, RS-485 TransceiverMAX3080–MAX3089: Fail-Safe, High-Speed (10Mbps), Slew-Rate-Limited, RS-485/RS-422Transceivers ♦For Space-Constrained Applications:MAX3460–MAX3464: +5V, Fail-Safe, 20Mbps,Profibus, RS-485/RS-422 TransceiversMAX3362: +3.3V, High-Speed, RS-485/RS-422Transceiver in a SOT23 PackageMAX3280E–MAX3284E: ±15kV ESD-Protected,52Mbps, +3V to +5.5V, SOT23, RS-485/RS-422True Fail-Safe ReceiversMAX3030E–MAX3033E: ±15kV ESD-Protected,+3.3V, Quad RS-422 Transmitters ♦For Multiple Transceiver Applications:MAX3293/MAX3294/MAX3295: 20Mbps, +3.3V,SOT23, RS-485/RS-422 Transmitters ♦For Fail-Safe Applications:MAX3440E–MAX3444E: ±15kV ESD-Protected,±60V Fault-Protected, 10Mbps, Fail-Safe RS-485/J1708 Transceivers ♦For Low-Voltage Applications:MAX3483E/MAX3485E/MAX3486E/MAX3488E/MAX3490E/MAX3491E: +3.3V Powered, ±15kV ESD-Protected, 12Mbps, Slew-Rate-Limited, True RS-485/RS-422 TransceiversMAX481E/MAX483E/MAX485E/MAX487E–MAX491E/MAX1487E±15kV ESD-Protected, Slew-Rate-Limited, Low-Power, RS-485/RS-422 Transceivers________________________________________________________________Maxim Integrated Products 1Ordering Information19-0410; Rev 4; 10/03For pricing, delivery, and ordering information,please contact Maxim/Dallas Direct!at 1-888-629-4642, or visit Maxim’s website at .Ordering Information continued at end of data sheet.Selector Guide appears at end of data sheet .M A X 481E /M A X 483E /M A X 485E /M A X 487E –M A X 491E /M A X 1487E±15kV ESD-Protected, Slew-Rate-Limited,Low-Power, RS-485/RS-422 Transceivers2_______________________________________________________________________________________Supply Voltage (V CC ) (12V)Control Input Voltage (–R —E –, DE)...................-0.5V to (V CC + 0.5V)Driver Input Voltage (DI).............................-0.5V to (V CC + 0.5V)Driver Output Voltage (Y, Z; A, B)..........................-8V to +12.5V Receiver Input Voltage (A, B).................................-8V to +12.5V Receiver Output Voltage (RO)....................-0.5V to (V CC + 0.5V)Continuous Power Dissipation (T A = +70°C)8-Pin Plastic DIP (derate 9.09mW/°C above +70°C)....727mW14-Pin Plastic DIP (derate 10.00mW/°C above +70°C)..800mW 8-Pin SO (derate 5.88mW/°C above +70°C).................471mW 14-Pin SO (derate 8.33mW/°C above +70°C)...............667mW Operating Temperature RangesMAX4_ _C_ _/MAX1487EC_ A.............................0°C to +70°C MAX4__E_ _/MAX1487EE_ A...........................-40°C to +85°C Storage Temperature Range.............................-65°C to +160°C Lead Temperature (soldering, 10sec).............................+300°CDC ELECTRICAL CHARACTERISTICS(V CC = 5V ±5%, T A = T MIN to T MAX , unless otherwise noted.) (Notes 1, 2)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.ABSOLUTE MAXIMUM RATINGSPARAMETERSYMBOL MINTYPMAX UNITS Driver Common-Mode Output VoltageV OC 3V Change in Magnitude of Driver Differential Output Voltage for Complementary Output States ∆V OD 0.2V Change in Magnitude of Driver Common-Mode Output Voltage for Complementary Output States ∆V OD 0.2V Input High Voltage V IH 2.0V Input Low Voltage V IL 0.8V Input CurrentI IN1±2µADifferential Driver Output (no load)V OD15V 2V Differential Driver Output (with load)V OD2 1.551.0-0.8mA0.25mA -0.2Receiver Differential Threshold Voltage-0.20.2V Receiver Input Hysteresis ∆V TH 70mV Receiver Output High Voltage V OH 3.5Receiver Output Low Voltage V OL 0.4V Three-State (high impedance)Output Current at ReceiverI OZR±1µA 12k ΩCONDITIONSDE = 0V;V CC = 0V or 5.25V,all devices except MAX487E/MAX1487E R = 27Ωor 50Ω, Figure 8R = 27Ωor 50Ω, Figure 8R = 27Ωor 50Ω, Figure 8DE, DI, –R —E–MAX487E/MAX1487E,DE = 0V, V CC = 0V or 5.25VDE, DI, –R —E–DE, DI, –R —E–-7V ≤V CM ≤12V V CM = 0VI O = -4mA, V ID = 200mV I O = 4mA, V ID = -200mV R = 50Ω(RS-422)0.4V ≤V O ≤2.4VR = 27Ω(RS-485), Figure 8-7V ≤V CM ≤12V, all devices except MAX487E/MAX1487EReceiver Input Resistance R IN-7V ≤V CM ≤12V, MAX487E/MAX1487E48k ΩV TH I IN2Input Current (A, B)V IN = 12V V IN = -7V V IN = 12V V IN = -7VVMAX481E/MAX483E/MAX485E/MAX487E–MAX491E/MAX1487E±15kV ESD-Protected, Slew-Rate-Limited,Low-Power, RS-485/RS-422 TransceiversSWITCHING CHARACTERISTICS—MAX481E/MAX485E, MAX490E/MAX491E, MAX1487EDC ELECTRICAL CHARACTERISTICS (continued)(V CC = 5V ±5%, T A = T MIN to T MAX , unless otherwise noted.) (Notes 1, 2)M A X 481E /M A X 483E /M A X 485E /M A X 487E –M A X 491E /M A X 1487E±15kV ESD-Protected, Slew-Rate-Limited,Low-Power, RS-485/RS-422 Transceivers4_______________________________________________________________________________________SWITCHING CHARACTERISTICS—MAX483E, MAX487E/MAX488E/MAX489E(V CC = 5V ±5%, T A = T MIN to T MAX , unless otherwise noted.) (Notes 1, 2)SWITCHING CHARACTERISTICS—MAX481E/MAX485E, MAX490E/MAX491E, MAX1487E(continued)(V CC = 5V ±5%, T A = T MIN to T MAX , unless otherwise noted.) (Notes 1, 2)2251000Figures 11 and 13, C L = 100pF, S2 closed Figures 11 and 13, C L = 100pF, S1 closed Figures 9 and 15, C L = 15pF, S2 closed,A - B = 2VCONDITIONSns 45100t ZH(SHDN)Driver Enable from Shutdown toOutput High (MAX481E)nsFigures 9 and 15, C L = 15pF, S1 closed,B - A = 2Vt ZL(SHDN)Receiver Enable from Shutdownto Output Low (MAX481E)ns 45100t ZL(SHDN)Driver Enable from Shutdown toOutput Low (MAX481E)ns 2251000t ZH(SHDN)Receiver Enable from Shutdownto Output High (MAX481E)UNITS MINTYP MAX SYMBOLPARAMETERt PLH t SKEW Figures 10 and 12, R DIFF = 54Ω,C L1= C L2= 100pFt PHL Figures 10 and 12, R DIFF = 54Ω,C L1= C L2= 100pFDriver Input to Output Driver Output Skew to Output ns 20800ns ns 2000MAX483E/MAX487E, Figures 11 and 13,C L = 100pF, S2 closedt ZH(SHDN)Driver Enable from Shutdown to Output High2502000ns2500MAX483E/MAX487E, Figures 9 and 15,C L = 15pF, S1 closedt ZL(SHDN)Receiver Enable from Shutdown to Output Lowns 2500MAX483E/MAX487E, Figures 9 and 15,C L = 15pF, S2 closedt ZH(SHDN)Receiver Enable from Shutdown to Output Highns 2000MAX483E/MAX487E, Figures 11 and 13,C L = 100pF, S1 closedt ZL(SHDN)Driver Enable from Shutdown to Output Lowns 50200600MAX483E/MAX487E (Note 5)t SHDN Time to Shutdownt PHL t PLH , t PHL < 50% of data period Figures 9 and 15, C RL = 15pF, S2 closed Figures 9 and 15, C RL = 15pF, S1 closed Figures 9 and 15, C RL = 15pF, S2 closed Figures 9 and 15, C RL = 15pF, S1 closed Figures 11 and 13, C L = 15pF, S2 closed Figures 10 and 14, R DIFF = 54Ω,C L1= C L2= 100pFFigures 11 and 13, C L = 15pF, S1 closed Figures 11 and 13, C L = 100pF, S1 closed Figures 11 and 13, C L = 100pF, S2 closed CONDITIONSkbps 250f MAX 2508002000Maximum Data Rate ns 2550t HZ Receiver Disable Time from High ns 25080020002550t LZ Receiver Disable Time from Low ns 2550t ZH Receiver Enable to Output High ns 2550t ZL Receiver Enable to Output Low ns ns 1003003000t HZ t SKD Driver Disable Time from High I t PLH - t PHL I DifferentialReceiver SkewFigures 10 and 14, R DIFF = 54Ω,C L1= C L2= 100pFns 3003000t LZ Driver Disable Time from Low ns 2502000t ZL Driver Enable to Output Low ns Figures 10 and 12, R DIFF = 54Ω,C L1= C L2= 100pFns 2502000t R , t F 2502000Driver Rise or Fall Time ns t PLH Receiver Input to Output2502000t ZH Driver Enable to Output High UNITS MIN TYP MAX SYMBOL PARAMETERMAX481E/MAX483E/MAX485E/MAX487E–MAX491E/MAX1487E±15kV ESD-Protected, Slew-Rate-Limited,Low-Power, RS-485/RS-422 Transceivers_______________________________________________________________________________________505101520253035404550OUTPUT CURRENT vs.RECEIVER OUTPUT LOW VOLTAGEM A X 481E -01OUTPUT LOW VOLTAGE (V)O U T P U T C U R R E N T (m A )1.52.02.51.00.50.10.20.30.40.50.60.70.80.9-60-2060RECEIVER OUTPUT LOW VOLTAGEvs. TEMPERATURETEMPERATURE (°C)O U T P U T L O W V O L T A G E (V )20100-4040800-5-10-15-20-251.53.0OUTPUT CURRENT vs.RECEIVER OUTPUT HIGH VOLTAGEM A X 481E -02OUTPUT HIGH VOLTAGE (V)O U T P U T C U R R E N T (m A )5.04.54.02.02.53.53.03.23.43.63.84.04.24.44.64.8-60-2060RECEIVER OUTPUT HIGH VOLTAGEvs. TEMPERATURETEMPERATURE (°C)O U T P U T H I G H V O L T A G E (V )20100-4040800102030405060708090DRIVER OUTPUT CURRENT vs. DIFFERENTIAL OUTPUT VOLTAGEM A X 481E -05DIFFERENTIAL OUTPUT VOLTAGE (V)O U T P U T C U R R E N T (m A )1.52.0 2.53.0 3.54.0 4.51.00.50__________________________________________Typical Operating Characteristics(V CC = 5V, T A = +25°C, unless otherwise noted.)NOTES FOR ELECTRICAL/SWITCHING CHARACTERISTICSNote 1:All currents into device pins are positive; all currents out of device pins are negative. All voltages are referenced to deviceground unless otherwise specified.Note 2:All typical specifications are given for V CC = 5V and T A = +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 MAX481E/MAX483E/MAX487E are put into shutdown by bringing –R —E –high and DE low. If the inputs are in this state forless 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.M A X 481E /M A X 483E /M A X 485E /M A X 487E –M A X 491E /M A X 1487E±15kV ESD-Protected, Slew-Rate-Limited,Low-Power, RS-485/RS-422 Transceivers6___________________________________________________________________________________________________________________Typical Operating Characteristics (continued)(V CC = 5V, T A = +25°C, unless otherwise noted.)1.52.32.22.12.01.91.81.71.6-60-2060DRIVER DIFFERENTIAL OUTPUT VOLTAGE vs. TEMPERATURETEMPERATURE (°C)D I F FE R E N T I A L O U T P U T V O L T A G E (V )20100-404080020406080100120140OUTPUT CURRENT vs. DRIVER OUTPUT LOW VOLTAGEM A X 481E -07OUTPUT LOW VOLTAGE (V)O U T P U T C U R R E N T (m A )246810120-10-20-30-40-50-60-70-80-90-100-8-2OUTPUT CURRENT vs. DRIVER OUTPUT HIGH VOLTAGEM A X 481E -08OUTPUT HIGH VOLTAGE (V)O U T P U T C U R R E N T (m A )642-6-400100200300400500600-60-2060MAX481E/MAX485E/MAX490E/MAX491E SUPPLY CURRENT vs. TEMPERATURETEMPERATURE (°C)S U P P L Y C U R R E N T (µA )20100-4040800100200300400500600-60-2060MAX483E/MAX487E–MAX489E SUPPLY CURRENT vs. TEMPERATURETEMPERATURE (°C)S U P P L Y C U R R E N T (µA )20100-404080100200300400500600-60-2060MAX1487ESUPPLY CURRENT vs. TEMPERATURETEMPERATURE (°C)S U P P L Y C U R R E N T (µA )20100-404080±15kV ESD-Protected, Slew-Rate-Limited, Low-Power, RS-485/RS-422 Transceivers_______________________________________________________________________________________7MAX481E/MAX483E/MAX485E/MAX487E–MAX491E/MAX1487E______________________________________________________________Pin DescriptionM A X 481E /M A X 483E /M A X 485E /M A X 487E –M A X 491E /M A X 1487E±15kV ESD-Protected, Slew-Rate-Limited,Low-Power, RS-485/RS-422 Transceivers8_________________________________________________________________________________________________Function Tables (MAX481E/MAX483E/MAX485E/MAX487E/MAX1487E) Table 1. Transmitting__________Applications Information The MAX481E/MAX483E/MAX485E/MAX487E–MAX491E and MAX1487E are low-power transceivers for RS-485 and RS-422 communications. These “E” versions of the MAX481, MAX483, MAX485, MAX487–MAX491, and MAX1487 provide extra protection against ESD. The rugged MAX481E, MAX483E, MAX485E, MAX497E–MAX491E, and MAX1487E are intended for harsh envi-ronments where high-speed communication is important. These devices eliminate the need for transient suppres-sor diodes and the associated high capacitance loading. The standard (non-“E”) MAX481, MAX483, MAX485, MAX487–MAX491, and MAX1487 are recommended for applications where cost is critical.The MAX481E, MAX485E, MAX490E, MAX491E, and MAX1487E can transmit and receive at data rates up to 2.5Mbps, while the MAX483E, MAX487E, MAX488E, and MAX489E are specified for data rates up to 250kbps. The MAX488E–MAX491E are full-duplex transceivers, while the MAX481E, MAX483E, MAX487E, and MAX1487E are half-duplex. In addition, driver-enable (DE) and receiver-enable (RE) pins are included on the MAX481E, MAX483E, MAX485E, MAX487E, MAX489E, MAX491E, and MAX1487E. When disabled, the driver and receiver outputs are high impedance.±15kV ESD Protection As with all Maxim devices, ESD-protection structures are incorporated on all pins to protect against electro-static discharges encountered during handling and assembly. The driver outputs and receiver inputs have extra protection against static electricity. Maxim’s engi-neers developed state-of-the-art structures to protect these pins against ESD of ±15kV without damage. The ESD structures withstand high ESD in all states: normal operation, shutdown, and powered down. After an ESD event, Maxim’s MAX481E, MAX483E, MAX485E, MAX487E–MAX491E, and MAX1487E keep working without latchup.ESD protection can be tested in various ways; the transmitter outputs and receiver inputs of this product family are characterized for protection to ±15kV using the Human Body Model.Other ESD test methodologies include IEC10004-2 con-tact discharge and IEC1000-4-2 air-gap discharge (for-merly IEC801-2).ESD Test Conditions ESD performance depends on a variety of conditions. Contact Maxim for a reliability report that documents test set-up, test methodology, and test results.Human Body Model Figure 4 shows the Human Body Model, and Figure 5 shows the current waveform it generates when dis-charged into a low impedance. This model consists of a 100pF capacitor charged to the ESD voltage of inter-est, which is then discharged into the test device through a 1.5kΩresistor.IEC1000-4-2 The IEC1000-4-2 standard covers ESD testing and per-formance of finished equipment; it does not specifically refer to integrated circuits (Figure 6).MAX481E/MAX483E/MAX485E/MAX487E–MAX491E/MAX1487E±15kV ESD-Protected, Slew-Rate-Limited,Low-Power, RS-485/RS-422 Transceivers_______________________________________________________________________________________9M A X 481E /M A X 483E /M A X 485E /M A X 487E –M A X 491E /M A X 1487E±15kV ESD-Protected, Slew-Rate-Limited,Low-Power, RS-485/RS-422 Transceivers10______________________________________________________________________________________Figure 8. Driver DC Test LoadFigure 9. Receiver Timing Test LoadMAX481E/MAX483E/MAX485E/MAX487E–MAX491E/MAX1487E±15kV ESD-Protected, Slew-Rate-Limited,Low-Power, RS-485/RS-422 Transceivers______________________________________________________________________________________11Figure 10. Driver/Receiver Timing Test Circuit Figure 11. Driver Timing Test LoadFigure 12. Driver Propagation DelaysFigure 13. Driver Enable and Disable Times (except MAX488E and MAX490E)Figure 14. Receiver Propagation DelaysFigure 15. Receiver Enable and Disable Times (except MAX488E and MAX490E)M A X 481E /M A X 483E /M A X 485E /M A X 487E –M A X 491E /M A X 1487E±15kV ESD-Protected, Slew-Rate-Limited,Low-Power, RS-485/RS-422 Transceivers12______________________________________________________________________________________The major difference between tests done using the Human Body Model and IEC1000-4-2 is higher peak current in IEC1000-4-2, because series resistance is lower in the IEC1000-4-2 model. Hence, the ESD with-stand voltage measured to IEC1000-4-2 is generally lower than that measured using the Human Body Model. Figure 7 shows the current waveform for the 8kV IEC1000-4-2 ESD contact-discharge test.The air-gap test involves approaching the device with a charged probe. The contact-discharge method connects the probe to the device before the probe is energized.Machine ModelThe Machine Model for ESD tests all pins using a 200pF storage capacitor and zero discharge resis-tance. Its objective is to emulate the stress caused by contact that occurs with handling and assembly during manufacturing. Of course, all pins require this protec-tion during manufacturing—not just inputs and outputs.Therefore,after PC board assembly,the Machine Model is less relevant to I/O ports.MAX487E/MAX1487E:128 Transceivers on the BusThe 48k Ω, 1/4-unit-load receiver input impedance of the MAX487E and MAX1487E allows up to 128 transceivers on a bus, compared to the 1-unit load (12k Ωinput impedance) of standard RS-485 drivers (32 transceivers maximum). Any combination of MAX487E/MAX1487E and other RS-485 transceivers with a total of 32 unit loads or less can be put on the bus. The MAX481E,MAX483E, MAX485E, and MAX488E–MAX491E have standard 12k Ωreceiver input impedance.MAX483E/MAX487E/MAX488E/MAX489E:Reduced EMI and Reflections The MAX483E and MAX487E–MAX489E are slew-rate limited, minimizing EMI and reducing reflections caused by improperly terminated cables. Figure 16shows the driver output waveform and its Fourier analy-sis of a 150kHz signal transmitted by a MAX481E,MAX485E, MAX490E, MAX491E, or MAX1487E. High-frequency harmonics with large amplitudes are evident.Figure 17 shows the same information displayed for a MAX483E, MAX487E, MAX488E, or MAX489E transmit-ting under the same conditions. Figure 17’s high-fre-quency harmonics have much lower amplitudes, and the potential for EMI is significantly reduced.Low-Power Shutdown Mode (MAX481E/MAX483E/MAX487E)A low-power shutdown mode is initiated by bringing both RE high and DE low. The devices will not shut down unless both the driver and receiver are disabled.In shutdown, the devices typically draw only 0.5µA of supply current.RE and DE may be driven simultaneously; the parts are 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.For the MAX481E, MAX483E, and MAX487E, the t ZH and t ZL enable times assume the part was not in the low-power shutdown state (the MAX485E, MAX488E–MAX491E, and MAX1487E can not be shut down). The t ZH(SHDN)and t ZL(SHDN)enable times assume the parts were shut down (see Electrical Characteristics ).500kHz/div0Hz5MHz 10dB/div Figure 16. Driver Output Waveform and FFT Plot ofMAX485E/MAX490E/MAX491E/MAX1487E Transmitting a 150kHz Signal500kHz/div0Hz5MHz10dB/divFigure 17. Driver Output Waveform and FFT Plot ofMAX483E/MAX487E–MAX489E Transmitting a 150kHz SignalIt takes the drivers and receivers longer to become enabled from the low-power shutdown state (t ZH(SHDN), t ZL(SHDN)) than from the operating mode (t ZH, t ZL). (The parts are in operating mode if the RE, DE inputs equal a logical 0,1 or 1,1 or 0, 0.)Driver Output Protection Excessive output current and power dissipation caused by faults or by bus contention are prevented by two mechanisms. A foldback current limit on the output stage provides immediate protection against short circuits over the whole common-mode voltage range (see Typical Operating Characteristics). In addition, a thermal shut-down circuit forces the driver outputs into a high-imped-ance state if the die temperature rises excessively.Propagation Delay Many digital encoding schemes depend on the differ-ence between the driver and receiver propagation delay times. Typical propagation delays are shown in Figures 19–22 using Figure 18’s test circuit.The difference in receiver delay times, t PLH- t PHL, is typically under 13ns for the MAX481E, MAX485E, MAX490E, MAX491E, and MAX1487E, and is typically less than 100ns for the MAX483E and MAX487E–MAX489E.The driver skew times are typically 5ns (10ns max) for the MAX481E, MAX485E, MAX490E, MAX491E, and MAX1487E, and are typically 100ns (800ns max) for the MAX483E and MAX487E–MAX489E.Typical Applications The MAX481E, MAX483E, MAX485E, MAX487E–MAX491E, and MAX1487E transceivers are designed for bidirectional data communications on multipoint bus transmission lines. Figures 25 and 26 show typical net-work application circuits. These parts can also be used as line repeaters, with cable lengths longer than 4000 feet. To minimize reflections, the line should be terminated at both ends in its characteristic impedance, and stub lengths off the main line should be kept as short as possi-ble. The slew-rate-limited MAX483E and MAX487E–MAX489E are more tolerant of imperfect termination. Bypass the V CC pin with 0.1µF.Isolated RS-485 For isolated RS-485 applications, see the MAX253 and MAX1480 data sheets.Line Length vs. Data Rate The RS-485/RS-422 standard covers line lengths up to 4000 feet. Figures 23 and 24 show the system differen-tial voltage for the parts driving 4000 feet of 26AWG twisted-pair wire at 110kHz into 100Ωloads.Figure 18. Receiver Propagation Delay Test CircuitMAX481E/MAX483E/MAX485E/MAX487E–MAX491E/MAX1487E±15kV ESD-Protected, Slew-Rate-Limited,Low-Power, RS-485/RS-422 Transceivers ______________________________________________________________________________________13M A X 481E /M A X 483E /M A X 485E /M A X 487E –M A X 491E /M A X 1487E±15kV ESD-Protected, Slew-Rate-Limited,Low-Power, RS-485/RS-422 Transceivers14______________________________________________________________________________________25ns/div 5V/divRO B A500mV/div Figure 19. MAX481E/MAX485E/MAX490E/MAX1487E Receiver t PHL25ns/div5V/div ROBA500mV/divFigure 20. MAX481E/MAX485E/MAX490E/MAX491E/MAX1487E Receiver t PLH200ns/div 5V/divRO B A500mV/div Figure 21. MAX483E/MAX487E–MAX489E Receiver t PHL200ns/div5V/div ROBA500mV/divFigure 22. MAX483E/MAX487E–MAX489E Receiver t PLH2µs/div DO 0V0V5V5V -1V 0DIV A - V BFigure 23. MAX481E/MAX485E/MAX490E/MAX491E/MAX1487E System Differential Voltage at 110kHz Driving 4000ft of Cable 2µs/divDO0V0V 5V 5V -1V1V0DIV B - V AFigure 24. MAX483E/MAX1487E–MAX489E System Differential Voltage at 110kHz Driving 4000ft of CableMAX481E/MAX483E/MAX485E/MAX487E–MAX491E/MAX1487E±15kV ESD-Protected, Slew-Rate-Limited,Low-Power, RS-485/RS-422 Transceivers______________________________________________________________________________________15Figure 26. MAX488E–MAX491E Full-Duplex RS-485 NetworkFigure 25. MAX481E/MAX483E/MAX485E/MAX487E/MAX1487E Typical Half-Duplex RS-485 NetworkM A X 481E /M A X 483E /M A X 485E /M A X 487E –M A X 491E /M A X 1487E±15kV ESD-Protected, Slew-Rate-Limited, Low-Power, RS-485/RS-422 Transceivers Maxim cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim product. No circuit patent licenses are implied. Maxim reserves the right to change the circuitry and specifications without notice at any time.16____________________Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600©2003 Maxim Integrated ProductsPrinted USAis a registered trademark of Maxim Integrated Products.Package InformationFor the latest package outline information, go to /packages .Ordering Information (continued)Selector GuideChip InformationTRANSISTOR COUNT: 295。
MAX485中文资料
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{ UBRR1H=0; UBRR1L=103; UCSR1B=(1<<RXCIE1)|(1<<RXEN1)|(1<<TXEN1); //发送接收使能，使用中断方式， UCSR1C=(1<<UCSZ10)|(1<<UCSZ11); //0x06 8 位数据，1 位停止位，无校验
SIGNAL(SIG_UART1_RECV)//serial port 1 {
if(UCSR1A&(1<<RXC1)) {
rec1buff=UDR1; rec1_flag=1; } }
MAX481,MAX483,MAX485,MAX487,MAX1487 引脚（管脚）图及工作电路
MAX485 通讯程序与 MAX232 通讯程序在本质上是一样的，只是 MAX485 通讯程序需要加上通讯方向控制。下面 是基于 mega128 16AU 的 485 通信中断接收的程序，调试通过,晶振为外部 16M,MAX485 的 DE 和 RE 短接连 PC
Generated by Foxit PDF Creator © Foxit Software For evaluation only. MAX485 中文资料，MAX485 PDF,DATASHEET,电路图，通讯程序内容介绍： 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、MAX48 7、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 250kbps 的无差错数据传输。MAX481、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 120(A 至 500(A 之间。另外，MAX481、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。
} void Usart1_tr式发送接收字符函数
Generated by Foxit PDF Creator © Foxit Software For evaluation only. { SEND_485; DelayBus();DelayBus();DelayBus(); while( !(UCSR1A&(1<<UDRE1)));//等待发送缓冲区为空 UDR1=c; while(!(UCSR1A&(1<<TXC1))); // UDCR0=c; UCSR1A |= _BV(TXC1);//将发送结束标志位清零 // SET_BIT(UCSR1A,); READ_485; direction++; }