MAX3232串口通信模块
基于电荷泵的单片机串口通信的热插拔设计
基于电荷泵的单片机串口通信的热插拔设计作者：朱雨蔡坚勇郑华等来源：《电子世界》2013年第17期【摘要】本文采用内部集成了电荷泵模块的MAX3232作为单片机串口通信的热插拔保护电路，该方案能够很好抑制热插拔所引入的尖峰电压，且电路简单，元件较少，以较低的成本获得较好的热插拔性能。
【关键词】热插拔；串口通信；热插拔；MAX32321.引言所谓热插拔，也就是在不切断系统电源的情况下，进行插入或者拔出的操作。
但在正常情况下，对正在工作中设备进行“热插拔”操作是不被允许的，并且“热插拔”的操作会带来许多“副作用”，例如会产生浪涌电流，瞬态电压，静电释放等效应[1][2][3]。
其中浪涌电流效应主要发生在系统的供电模块，而瞬态电压和静电释放效应主要发生在信号端口。
这些效应会导致一些严重后果，例如，单片机不正常复位，单片机端口损坏，一些重要的IC芯片乃至整个电路板烧毁。
但是由于各种原因，例如操作人员疏忽和一些特殊的应用需求，必须保证电路板在热插拔操作的情况下仍然能够正常工作。
因此本文根据单片机串口通信模块需要具备热插拔特殊应用需求，针对热插拔操作所带来的后两种危害设计了相应的保护电路。
2.设计方案比较由于不同设备之间存在电位差的缘故，虽然这些电位差是瞬间的，且电流量并不大，但是在进行热插拔操作时，该电位差通常会超过各种IC芯片的最大耐压值，甚至是IC芯片最大耐压值的几倍从而烧毁IC芯片。
解决瞬态电压的方法就是快速钳制电压。
目前常见的手段包括在电压输入端和地之间使用压敏电阻，TVS（Transient Voltage Suppresser）二极管，也可以使用多层变阻器以及电荷泵电路[3][4]。
如表1所示设计方案的比较。
3.电荷泵的工作原理电荷泵的有许多种分类方法，其中按照内部的结构不同可分为三类：（1）开关式调整器升压泵；（2）无调整电容式电荷泵；（3）可调整电容式电荷泵。
按照输出压降不同，可分为倍圧型和负压型两种。
MAX3232中文资料.pdf
MAX3222/MAX3232/MAX3237/MAX32413.0V至5.5V、低功耗、1Mbps、真RS-232收发器，使用四只0.1µF外部电容________________________________________________________________Maxim Integrated Products119-0273; Rev 7; 1/07MegaBaud和UCSP是Maxim Integrated Products, Inc.的商标。
本文是英文数据资料的译文，文中可能存在翻译上的不准确或错误。
如需进一步确认，请在您的设计中参考英文资料。
有关价格、供货及订购信息，请联络Maxim亚洲销售中心：10800 852 1249 (北中国区)，10800 152 1249 (南中国区)，或访问Maxim的中文网站：。
M A X 3222/M A X 3232/M A X 3237/M A X 32413.0V至5.5V、低功耗、1Mbps、真RS-232收发器，使用四只0.1µF外部电容2_______________________________________________________________________________________ABSOLUTE MAXIMUM RATINGSELECTRICAL CHARACTERISTICS(V CC = +3.0V to +5.5V, C1–C4 = 0.1µF (Note 2), T A = T MIN to T MAX , unless otherwise noted. Typical values are at T A = +25°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.Note 1:V+ and V- can have a maximum magnitude of 7V, but their absolute difference cannot exceed 13V.V CC ...........................................................................-0.3V to +6V V+ (Note 1)...............................................................-0.3V to +7V V- (Note 1)................................................................+0.3V to -7V V+ + V- (Note 1)...................................................................+13V Input VoltagesT_IN, SHDN , EN ...................................................-0.3V to +6V MBAUD...................................................-0.3V to (V CC + 0.3V)R_IN.................................................................................±25V Output VoltagesT_OUT...........................................................................±13.2V R_OUT....................................................-0.3V to (V CC + 0.3V)Short-Circuit DurationT_OUT....................................................................ContinuousContinuous Power Dissipation (T A = +70°C)16-Pin TSSOP (derate 6.7mW/°C above +70°C).............533mW 16-Pin Narrow SO (derate 8.70mW/°C above +70°C)....696mW 16-Pin Wide SO (derate 9.52mW/°C above +70°C)........762mW 16-Pin Plastic DIP (derate 10.53mW/°C above +70°C)...842mW 18-Pin SO (derate 9.52mW/°C above +70°C)..............762mW 18-Pin Plastic DIP (derate 11.11mW/°C above +70°C)..889mW 20-Pin SSOP (derate 7.00mW/°C above +70°C).........559mW 20-Pin TSSOP (derate 8.0mW/°C above +70°C).............640mW 28-Pin TSSOP (derate 8.7mW/°C above +70°C).............696mW 28-Pin SSOP (derate 9.52mW/°C above +70°C).........762mW 28-Pin SO (derate 12.50mW/°C above +70°C).....................1W Operating Temperature RangesMAX32_ _C_ _.....................................................0°C to +70°C MAX32_ _E_ _ .................................................-40°C to +85°C Storage Temperature Range.............................-65°C to +150°C Lead Temperature (soldering, 10s).................................+300°CMAX3222/MAX3232/MAX3237/MAX32413.0V至5.5V、低功耗、1Mbps、真RS-232收发器，使用四只0.1µF外部电容_______________________________________________________________________________________3TIMING CHARACTERISTICS—MAX3222/MAX3232/MAX3241(V CC = +3.0V to +5.5V, C1–C4 = 0.1µF (Note 2), T A = T MIN to T MAX , unless otherwise noted. Typical values are at T A = +25°C.)ELECTRICAL CHARACTERISTICS (continued)(V CC = +3.0V to +5.5V, C1–C4 = 0.1µF (Note 2), T A = T MIN to T MAX , unless otherwise noted. Typical values are at T A = +25°C.)A X 3222/M A X 3232/M A X 3237/M A X 32413.0V至5.5V、低功耗、1Mbps、真RS-232收发器，使用四只0.1µF外部电容4_______________________________________________________________________________________典型工作特性Ω, T A = +25°C, unless otherwise noted.)LOAD CAPACITANCE (pF)0246810121416182022150MAX3222/MAX3232SLEW RATEvs. LOAD CAPACITANCELOAD CAPACITANCE (pF)S L E W R A T E (V /µs )20003000100040005000510152025303540MAX3222/MAX3232SUPPLY CURRENT vs. LOAD CAPACITANCEWHEN TRANSMITTING DATALOAD CAPACITANCE (pF)S U P P L Y C U R R E N T (m A )20003000100040005000TIMING CHARACTERISTICS—MAX3237(V CC = +3.0V to +5.5V, C1–C4 = 0.1µF (Note 2), T A = T MIN to T MAX , unless otherwise noted. Typical values are at T A = +25°C.)Note 2:MAX3222/MAX3232/MAX3241: C1–C4 = 0.1µF tested at 3.3V ±10%; C1 = 0.047µF, C2–C4 = 0.33µF tested at 5.0V ±10%.MAX3237: C1–C4 = 0.1µF tested at 3.3V ±5%; C1–C4 = 0.22µF tested at 3.3V ±10%; C1 = 0.047µF, C2–C4 = 0.33µF tested at 5.0V ±10%.Note 3:Transmitter input hysteresis is typically 250mV.MAX3222/MAX3232/MAX3237/MAX32413.0V至5.5V、低功耗、1Mbps、真RS-232收发器，使用四只0.1µF外部电容_______________________________________________________________________________________5-7.5-5.0-2.502.55.07.50MAX3241TRANSMITTER OUTPUT VOLTAGEvs. LOAD CAPACITANCELOAD CAPACITANCE (pF)T R A N S M I T T E R O U T P U T V O L T A G E (V )2000300010004000500046810121416182022240MAX3241SLEW RATEvs. LOAD CAPACITANCELOAD CAPACITANCE (pF)S L E W R A T E (V /µs )20003000100040005000510152025303545400MAX3241SUPPLY CURRENT vs. LOADCAPACITANCE WHEN TRANSMITTING DATALOAD CAPACITANCE (pF)S U P P L Y C U R R E N T (m A )20003000100040005000-7.5-5.0-2.502.55.07.50MAX3237TRANSMITTER OUTPUT VOLTAGE vs. LOAD CAPACITANCE (MBAUD = GND)LOAD CAPACITANCE (pF)T R A N S M I T T E R O U T P U T V O L T A G E (V )200030001000400050000102030504060700MAX3237SLEW RATE vs. LOAD CAPACITANCE(MBAUD = V CC )LOAD CAPACITANCE (pF)S L E W R A T E (V /µs )500100015002000-7.5-5.0-2.502.55.07.50MAX3237TRANSMITTER OUTPUT VOLTAGE vs. LOAD CAPACITANCE (MBAUD = V CC )LOAD CAPACITANCE (pF)T R A N S M I T T E R O U T P U T V O L T A G E (V )5001000150020001020304050600MAX3237SUPPLY CURRENT vs.LOAD CAPACITANCE (MBAUD = GND)LOAD CAPACITANCE (pF)S U P P L Y C U R R E N T (m A )200030001000400050000246810120MAX3237SLEW RATE vs. LOAD CAPACITANCE(MBAUD = GND)LOAD CAPACITANCE (pF)S L E W R A T E (V /µs )2000300010004000500010302040506070MAX3237SKEW vs. LOAD CAPACITANCE(t PLH - t PHL )LOAD CAPACITANCE (pF)1000150050020002500____________________________________________________________________典型工作特性(续)(V CC = +3.3V, 235kbps data rate, 0.1µF capacitors, all transmitters loaded with 3k Ω, T A = +25°C, unless otherwise noted.)M A X 3222/M A X 3232/M A X 3237/M A X 32413.0V至5.5V、低功耗、1Mbps、真RS-232收发器，使用四只0.1µF外部电容6_________________________________________________________________________________________________________________________________________________________________引脚说明MAX3222/MAX3232/MAX3237/MAX32413.0V至5.5V、低功耗、1Mbps、真RS-232收发器，使用四只0.1µF外部电容_______________________________________________________________________________________7_______________________________详细说明双电荷泵电压转换器MAX3222/MAX3232/MAX3237/MAX3241的内部电源由两路稳压型电荷泵组成，只要输入电压(V CC )在3.0V至5.5V范围以内，即可提供+5.5V (倍压电荷泵)和-5.5V (反相电荷泵)输出电压。
国产max3232
国产MAX3232简介MAX3232是一款常用的RS232转换芯片，用于在电脑和外部设备之间传递串行数据。
国产MAX3232是国内厂商生产的一种与MAXIM公司生产的MAX3232功能相似的芯片。
国产MAX3232在功能和参数上与MAX3232基本保持一致，但在价格和供货上具有一定优势。
功能特点1.支持RS232标准，实现电平转换。
2.具有高速数据传输能力，通信稳定可靠。
3.低功耗设计，节能环保。
4.集成了保护功能，具有较好的抗干扰能力。
5.独特的设计使其适用于各种工业和通讯场景。
国产MAX3232与进口MAX3232的比较1.价格：国产MAX3232的价格通常比进口MAX3232更为具有竞争力，降低成本。
2.供货周期：国产MAX3232生产商在国内，供货更为便捷，缩短采购周期。
3.技术支持：国产MAX3232的厂商提供本地化的技术支持，解决问题更为便捷。
4.适用性：国产MAX3232根据国内市场的需求进行定制和优化，更适合国内用户需求。
应用场景1.工控设备：国产MAX3232可广泛应用于工控设备中，实现设备之间的稳定通信。
2.通信设备：在通信设备中，国产MAX3232可以帮助设备与中控系统之间实现数据传输。
3.个人DIY项目：爱好者可以利用国产MAX3232进行串口通信的DIY项目，提高通信稳定性。
结论国产MAX3232是一款功能齐全、价格优势明显的RS232转换芯片，可以满足各类通信设备的需求。
国产MAX3232在本地化支持、技术服务等方面具备诸多优势，为用户提供了更好的使用体验。
在未来的发展中，国产MAX3232有望在国内市场越发广泛地应用于各类通信、工控等领域。
MAX3232每次只有在上电后，再连接串口线正常——保护电阻。RS232防雷保护
MAX3232每次只有在上电后，再连接串⼝线正常——保护电阻。
RS232防雷保护原问题：做了块电路板，结果发现，要先对开发板上电, 再打开串⼝超级终端, 串⼝通信才可成功。
但是另外⼀块开发板却没有这个问题。
这⼀般是什么原因造成的？⾃⼰遇到问题：刚焊接好的板⼦，发现串⼝有问题，结果串⼝每次只有在断电上电后需要在上电后重新连接串⼝线才能正常通信原因简述：缺少保护电阻，解决办法：每次断电时拔掉串⼝线下⾯所提到的问题，和上⾯链接中的问题(热插拔才可通信)，其实是同⼀个问题，可能的原因是1. 232收发器芯⽚产⽣电压的那些⼩电容的数值是和数据⼿册上不太⼀致2. 232收发器芯⽚和232插座之间缺少串联保护电阻，或保护电阻数值太⼩。
3. 原来的232收发器芯⽚可能部分失效了如果1和2都已经做到了，将232收发器芯⽚的RXD输⼊管脚和插座RXD之间的串联保护电阻加⼤，⽐如换成1K或10K的，应该就可以了。
如果还不成，就换个232芯⽚吧。
多说⼏句原因吧(以前碰到过该问题所以就研究过)：在不通信的时候，PC串⼝的TXD管脚会输出-5V左右的电压，于是在开发板上的232收发器芯⽚的RXD对应的输⼊管脚(R1IN或R2IN)上维持着-5V左右的电压。
当开发板断电时，232收发器芯⽚的电源管脚没有电压，V+/V-管脚也没有电压，唯独RXD输⼊管脚(R1IN或R2IN)上维持这⼀个-5V左右的电平，不⽤多说就能明⽩这意味着什么。
假如习惯上每次给开发板断电后却让串⼝依旧和 PC保持连接，这意味这232收发器芯⽚长期承受着RXD输⼊管脚-5V但同时⼜让电源管脚和V+/V-为零电平，特别当PC的TXD输出维持这超过-5V甚⾄超过-6V的时候，久⽽久之，这颗芯⽚就会渐渐部分失效或全部失效，于是通信就失败了。
所以换⼀个芯⽚往往就可以解决这个问题。
每次先打开串⼝程序⽽没有通信的时候，-5V或以下的电压就加在TXD管脚上了，如果此时开发板断电但是却接着串⼝，就相当于初始状态是先让232收发器芯⽚处于上述异常的⼯作条件，然后再给开发板上电的时候，就可能出现通信不成功的状况。
MAX3232中文资料_数据手册_参数
单片机与node mcu串口通信的接线方法(一)
单片机与node mcu串口通信的接线方法(一)单片机与NodeMCU串口通信的接线方法介绍在项目开发中，单片机与NodeMCU之间的串口通信是常见的需求。
本文将详细介绍多种串口通信接线方法，包括硬件和软件方面的配置。
硬件接线方法直接连接1.将单片机的TX引脚连接到NodeMCU的RX引脚上。
2.将单片机的RX引脚连接到NodeMCU的TX引脚上。
3.确保单片机和NodeMCU共用一个地线。
使用转接模块1.使用一个串口转接模块，如MAX3232、CP2102等。
2.将单片机的TX引脚连接到转接模块的RX引脚上。
3.将单片机的RX引脚连接到转接模块的TX引脚上。
4.将转接模块的VCC引脚连接到单片机的电源引脚或NodeMCU的5V引脚上。
5.将转接模块的GND引脚连接到单片机的地线或NodeMCU的地线上。
使用逻辑电平转换器1.使用一个逻辑电平转换器模块，如CD4050、74HC4050等。
2.将单片机的TX引脚连接到逻辑电平转换器的输入引脚上。
3.将逻辑电平转换器的输出引脚连接到NodeMCU的RX引脚上。
4.将逻辑电平转换器的VCC引脚连接到单片机的电源引脚或NodeMCU的5V引脚上。
5.将逻辑电平转换器的GND引脚连接到单片机的地线或NodeMCU的地线上。
软件配置方法单片机编程1.在单片机的程序中设置串口通信相关的参数，如波特率、数据位、校验位等。
2.初始化串口，并确保单片机的接收和发送功能都已开启。
3.在主程序中编写发送和接收数据的代码。
NodeMCU编程1.在NodeMCU的程序中引入Serial库。
2.初始化串口，并设置相关的参数，如波特率、数据位、校验位等。
3.在主程序中编写发送和接收数据的代码，使用Serial库提供的函数进行串口通信。
总结本文介绍了单片机与NodeMCU之间串口通信的多种接线方法，包括直接连接、使用转接模块和使用逻辑电平转换器。
同时，也提到了软件配置方面的方法，包括单片机和NodeMCU的编程配置。
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MAX3232电平转换原理图
RS232TO TTL 通讯模块
实现RS232到TTL数据转换。
芯片采用MAX3232适用电压3V-5.5V,具有ESD保护功能、支持流控制、零延时自动收发转换和波特率自适应特点，即插即用，稳定可靠。
主要资源：
一、DB9母头RS232接口带流控功能可直接接电脑
二、2.54排针RS232接口带流控功能可替代DB9接头
三、3个指示灯分别是电源指示灯、数据收指示灯、数据发指示灯
四、2.54排针TTL接口带流控功能可直接接TTL设备
淘宝网站
https:///?spm=2013.1.1000126.d21.lOnOC1
以MCU单片机TTL到PC台式机RS232数据通信为例
1、PC台式机接DB9接口
2、MCU通过杜邦线接排针P1接口
P1接口说明
1GND接GND信号流向：GND
2VCC接3V-5V信号流向：VCC<--MCU_5V/MCU_3.3V
3RX接MCU_TX信号流向：PC_RX<--MAX3232<--RX
4TX接MCU_RX信号流向：PC_TX-->MAX3232-->TX
5CTS接MCU_RTS信号流向：PC_CTS<--MAX3232<--MCU_RTS 6RTS接MCU_CTS信号流向：PC_RTS-->MAX3232-->MCU_CTS
产品附件
1、RS232-TTL小板一个
2、杜邦线十根十种颜色
3、防静电自封袋一个
4、原理图
淘宝
https:///?spm=2013.1.1000126.d21.lOnOC1产品图片。
MAX3232中文资料
MAX3222/MAX3232/MAX3237/MAX32413.0V至5.5V、低功耗、1Mbps、真RS-232收发器，使用四只0.1µF外部电容________________________________________________________________Maxim Integrated Products119-0273; Rev 7; 1/07MegaBaud和UCSP是Maxim Integrated Products, Inc.的商标。
本文是英文数据资料的译文，文中可能存在翻译上的不准确或错误。
如需进一步确认，请在您的设计中参考英文资料。
有关价格、供货及订购信息，请联络Maxim亚洲销售中心：10800 852 1249 (北中国区)，10800 152 1249 (南中国区)，或访问Maxim的中文网站：。
M A X 3222/M A X 3232/M A X 3237/M A X 32413.0V至5.5V、低功耗、1Mbps、真RS-232收发器，使用四只0.1µF外部电容2_______________________________________________________________________________________ABSOLUTE MAXIMUM RATINGSELECTRICAL CHARACTERISTICS(V CC = +3.0V to +5.5V, C1–C4 = 0.1µF (Note 2), T A = T MIN to T MAX , unless otherwise noted. Typical values are at T A = +25°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.Note 1:V+ and V- can have a maximum magnitude of 7V, but their absolute difference cannot exceed 13V.V CC ...........................................................................-0.3V to +6V V+ (Note 1)...............................................................-0.3V to +7V V- (Note 1)................................................................+0.3V to -7V V+ + V- (Note 1)...................................................................+13V Input VoltagesT_IN, SHDN , EN ...................................................-0.3V to +6V MBAUD...................................................-0.3V to (V CC + 0.3V)R_IN.................................................................................±25V Output VoltagesT_OUT...........................................................................±13.2V R_OUT....................................................-0.3V to (V CC + 0.3V)Short-Circuit DurationT_OUT....................................................................ContinuousContinuous Power Dissipation (T A = +70°C)16-Pin TSSOP (derate 6.7mW/°C above +70°C).............533mW 16-Pin Narrow SO (derate 8.70mW/°C above +70°C)....696mW 16-Pin Wide SO (derate 9.52mW/°C above +70°C)........762mW 16-Pin Plastic DIP (derate 10.53mW/°C above +70°C)...842mW 18-Pin SO (derate 9.52mW/°C above +70°C)..............762mW 18-Pin Plastic DIP (derate 11.11mW/°C above +70°C)..889mW 20-Pin SSOP (derate 7.00mW/°C above +70°C).........559mW 20-Pin TSSOP (derate 8.0mW/°C above +70°C).............640mW 28-Pin TSSOP (derate 8.7mW/°C above +70°C).............696mW 28-Pin SSOP (derate 9.52mW/°C above +70°C).........762mW 28-Pin SO (derate 12.50mW/°C above +70°C).....................1W Operating Temperature RangesMAX32_ _C_ _.....................................................0°C to +70°C MAX32_ _E_ _ .................................................-40°C to +85°C Storage Temperature Range.............................-65°C to +150°C Lead Temperature (soldering, 10s).................................+300°CMAX3222/MAX3232/MAX3237/MAX32413.0V至5.5V、低功耗、1Mbps、真RS-232收发器，使用四只0.1µF外部电容_______________________________________________________________________________________3TIMING CHARACTERISTICS—MAX3222/MAX3232/MAX3241(V CC = +3.0V to +5.5V, C1–C4 = 0.1µF (Note 2), T A = T MIN to T MAX , unless otherwise noted. Typical values are at T A = +25°C.)ELECTRICAL CHARACTERISTICS (continued)(V CC = +3.0V to +5.5V, C1–C4 = 0.1µF (Note 2), T A = T MIN to T MAX , unless otherwise noted. Typical values are at T A = +25°C.)M A X 3222/M A X 3232/M A X 3237/M A X 32413.0V至5.5V、低功耗、1Mbps、真RS-232收发器，使用四只0.1µF外部电容4________________________________________________________________________________________________________________________________________________________________典型工作特性(V CC = +3.3V, 235kbps data rate, 0.1µF capacitors, all transmitters loaded with 3k Ω, T A = +25°C, unless otherwise noted.)-6-5-4-3-2-101234560MAX3222/MAX3232TRANSMITTER OUTPUT VOLTAGEvs. LOAD CAPACITANCELOAD CAPACITANCE (pF)T R A N S M I T T E R O U T P U T V O L T A G E (V )20003000100040005000246810121416182022150MAX3222/MAX3232SLEW RATEvs. LOAD CAPACITANCELOAD CAPACITANCE (pF)S L E W R A T E (V /µs )20003000100040005000510152025303540MAX3222/MAX3232SUPPLY CURRENT vs. LOAD CAPACITANCEWHEN TRANSMITTING DATALOAD CAPACITANCE (pF)S U P P L Y C U R R E N T (m A )20003000100040005000TIMING CHARACTERISTICS—MAX3237(V CC = +3.0V to +5.5V, C1–C4 = 0.1µF (Note 2), T A = T MIN to T MAX , unless otherwise noted. Typical values are at T A = +25°C.)Note 2:MAX3222/MAX3232/MAX3241: C1–C4 = 0.1µF tested at 3.3V ±10%; C1 = 0.047µF, C2–C4 = 0.33µF tested at 5.0V ±10%.MAX3237: C1–C4 = 0.1µF tested at 3.3V ±5%; C1–C4 = 0.22µF tested at 3.3V ±10%; C1 = 0.047µF, C2–C4 = 0.33µF tested at 5.0V ±10%.Note 3:Transmitter input hysteresis is typically 250mV.MAX3222/MAX3232/MAX3237/MAX32413.0V至5.5V、低功耗、1Mbps、真RS-232收发器，使用四只0.1µF外部电容_______________________________________________________________________________________5-7.5-5.0-2.502.55.07.50MAX3241TRANSMITTER OUTPUT VOLTAGEvs. LOAD CAPACITANCELOAD CAPACITANCE (pF)T R A N S M I T T E R O U T P U T V O L T A G E (V )2000300010004000500046810121416182022240MAX3241SLEW RATEvs. LOAD CAPACITANCELOAD CAPACITANCE (pF)S L E W R A T E (V /µs )20003000100040005000510152025303545400MAX3241SUPPLY CURRENT vs. LOADCAPACITANCE WHEN TRANSMITTING DATALOAD CAPACITANCE (pF)S U P P L Y C U R R E N T (m A )20003000100040005000-7.5-5.0-2.502.55.07.50MAX3237TRANSMITTER OUTPUT VOLTAGE vs. LOAD CAPACITANCE (MBAUD = GND)LOAD CAPACITANCE (pF)T R A N S M I T T E R O U T P U T V O L T A G E (V )200030001000400050000102030504060700MAX3237SLEW RATE vs. LOAD CAPACITANCE(MBAUD = V CC )LOAD CAPACITANCE (pF)S L E W R A T E (V /µs )500100015002000-7.5-5.0-2.502.55.07.50MAX3237TRANSMITTER OUTPUT VOLTAGE vs. LOAD CAPACITANCE (MBAUD = V CC )LOAD CAPACITANCE (pF)T R A N S M I T T E R O U T P U T V O L T A G E (V )5001000150020001020304050600MAX3237SUPPLY CURRENT vs.LOAD CAPACITANCE (MBAUD = GND)LOAD CAPACITANCE (pF)S U P P L Y C U R R E N T (m A )200030001000400050000246810120MAX3237SLEW RATE vs. LOAD CAPACITANCE(MBAUD = GND)LOAD CAPACITANCE (pF)S L E W R A T E (V /µs )2000300010004000500010302040506070MAX3237SKEW vs. LOAD CAPACITANCE(t PLH - t PHL )LOAD CAPACITANCE (pF)1000150050020002500____________________________________________________________________典型工作特性(续)(V CC = +3.3V, 235kbps data rate, 0.1µF capacitors, all transmitters loaded with 3k Ω, T A = +25°C, unless otherwise noted.)M A X 3222/M A X 3232/M A X 3237/M A X 32413.0V至5.5V、低功耗、1Mbps、真RS-232收发器，使用四只0.1µF外部电容6_________________________________________________________________________________________________________________________________________________________________引脚说明MAX3222/MAX3232/MAX3237/MAX32413.0V至5.5V、低功耗、1Mbps、真RS-232收发器，使用四只0.1µF外部电容_______________________________________________________________________________________7_______________________________详细说明双电荷泵电压转换器MAX3222/MAX3232/MAX3237/MAX3241的内部电源由两路稳压型电荷泵组成，只要输入电压(V CC )在3.0V至5.5V范围以内，即可提供+5.5V (倍压电荷泵)和-5.5V (反相电荷泵)输出电压。
max3232工作原理
max3232工作原理
MAX3232是一款集成电路，工作原理如下：
1. RS-232转换：MAX3232主要用于将RS-232标准电平转换为适合微控制器或其他低压逻辑电平的电平。
RS-232电平通常为正负12V，而微控制器或其他逻辑电路的工作电平通常为0V和3.3V或5V。
MAX3232通过内部电压调节器和双向电平转换电路实现将RS-232电平转换为适合逻辑电路的电平。
2. 电平转换：MAX3232内部有电平转换电路，能够将RS-232接收和发送的电平转换为适合逻辑电路的电平。
当RS-232接收信号为高电平时，MAX3232将其转换为逻辑电路所能接受的高电平信号。
当RS-232接收信号为低电平时，MAX3232
将其转换为逻辑电路所能接受的低电平信号。
3. 信号调整：MAX3232还能调整RS-232信号的电平幅度。
RS-232标准定义了标准电平和标准电平范围。
不同设备可能对电平范围有不同的要求。
MAX3232内部的电平调整电路可以根据需求调整出适合各种设备的信号电平。
总的来说，MAX3232的工作原理是通过将RS-232标准电平转换为适合逻辑电路的电平，并调整信号的电平幅度，实现RS-232与微控制器或其他逻辑电路的连接。
51单片机串口通信实例
51单片机串口通信实例一、原理简介51 单片机内部有一个全双工串行接口。
什么叫全双工串口呢?一般来说，只能接受或只能发送的称为单工串行;既可接收又可发送，但不能同时进行的称为半双工;能同时接收和发送的串行口称为全双工串行口。
串行通信是指数据一位一位地按顺序传送的通信方式，其突出优点是只需一根传输线，可大大降低硬件成本，适合远距离通信。
其缺点是传输速度较低。
与之前一样，首先我们来了解单片机串口相关的寄存器。
SBUF 寄存器：它是两个在物理上独立的接收、发送缓冲器，可同时发送、接收数据，可通过指令对SBUF 的读写来区别是对接收缓冲器的操作还是对发送缓冲器的操作。
从而控制外部两条独立的收发信号线RXD(P3.0)、TXD(P3.1)，同时发送、接收数据，实现全双工。
串行口控制寄存器SCON(见表1) 。
表1 SCON寄存器表中各位(从左至右为从高位到低位)含义如下。
SM0 和SM1 ：串行口工作方式控制位，其定义如表2 所示。
表2 串行口工作方式控制位其中，fOSC 为单片机的时钟频率;波特率指串行口每秒钟发送(或接收)的位数。
SM2 ：多机通信控制位。
该仅用于方式2 和方式3 的多机通信。
其中发送机SM2 = 1(需要程序控制设置)。
接收机的串行口工作于方式2 或3，SM2=1 时，只有当接收到第9 位数据(RB8)为1 时，才把接收到的前8 位数据送入SBUF，且置位RI 发出中断申请引发串行接收中断，否则会将接受到的数据放弃。
当SM2=0 时，就不管第位数据是0 还是1，都将数据送入SBUF，并置位RI 发出中断申请。
工作于方式0 时，SM2 必须为0。
REN ：串行接收允许位：REN =0 时，禁止接收;REN =1 时，允许接收。
TB8 ：在方式2、3 中，TB8 是发送机要发送的第9 位数据。
在多机通信中它代表传输的地址或数据，TB8=0 为数据，TB8=1 时为地址。
RB8 ：在方式2、3 中，RB8 是接收机接收到的第9 位数据，该数据正好来自发送机的TB8，从而识别接收到的数据特征。
MAX33250E和MAX33251E RS-232 串行转换接收器说明书
MAX33251EELC+General DescriptionThe MAX33250E and MAX33251E are isolated2Tx/2Rx and1Tx/1Rx RS-232transceivers,respectively,with a galvanic isolation of600V RMS(60sec)between the logic UART side and field side.The isolation barrier protects the logic UART side from electrical transient strikes from the field side.It also breaks ground loops and large dif-ferences in ground potentials between the two sides that can potentially corrupt the receiving and sending of data. The MAX33250E and MAX33251E conform to the EIA/ TIA-232E standard and operate at data rates up to1Mbps. The isolated RS-232transceivers have integrated charge pumps and an inverter to eliminate the need for a high positive and negative voltage supply.Both devices also have integrated charge pump and inverter capacitors to help further reduce PCB space.The supply pin V CCA on the UART logic side operates from a dual voltage sup-ply from+3V to+5.5V.V CCB also operates from+3V to +5.5V,simplifying power requirements and enabling lev-el translation between the two voltages.The transmitters and receivers on the field side of these devices are rated for±15kV of ESD HBM protection,suitable for applications where RS-232 cables are frequently worked on.Both are available in a12-pin,6mm x6mm LGA package and operate over the -40ºC to +85ºC temperature range.Applications●Diagnostics Equipment●POS Systems●Industrial Equipment●GPS Equipment●Communication Systems●Medical Equipment Benefits and Features●High Integration Saves Space and Simplifies Designs•Integrated Charge Pumps and Inverter Eliminates Extra Power Supplies•Four Internal Capacitors Saves PCB Space•Integrated Isolator Saves Up to 63% Versus a Discrete Solution●Integrated Protection for Robust Communications•600V RMS Withstand Isolation Voltage for 60 Seconds (V ISO)•200V RMS Working Voltage for >50 years (V IOWM)•Integrated ±15kV ESD Human Body Model (HBM) Ordering Information appears at end of data sheet.Click here for production status of specific part numbers.MAX33250E/ MAX33251E 600V Isolated 2Tx/2Rx and 1Tx/1Rx RS-232Transceiver with ±15kV ESDand Integrated CapacitorsEVALUATION KIT AVAILABLE19-100400, Rev 1; 11/18Absolute Maximum RatingsV CCA to GNDA.........................................................-0.3V to +6V V CCB to GNDB.........................................................-0.3V to +6V T_IN to GNDA..........................................................-0.3V to +6V T_OUT to GNDB...............................................................±13.2V R_IN to GNDB......................................................................±25V R_OUT to GNDA......................................................-0.3V to +6V Short-Circuit Duration (T_OUT to GNDB)..................Continuous Short-Circuit Duration (R_OUT to GNDA)..................ContinuousSide A (V CCA , T1IN, T2IN, R1OUT, R2OUT) to GNDA ESD±2kV Side B (V CCB ) to GNDB ESD...............................................±2kV Side B (T1OUT, T2OUT, R1IN, R2IN) to GNDB ESD HBM±15kV Continuous Power Dissipation (Single Layer Board)(T A =+70°C,derate 10mW/°C above +70°C.)...........................510mW Continuous Power Dissipation (Multilayer Board)(T A =+70°C,derate 10mW/°C above +70°C.)...........................700mW Operating Temperature Range.............................-40°C to +85°CStresses 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.Package InformationLGA-12For the latest package outline information and land patterns (footprints), go to /packages .Note that a “+”, “#”, or “-” in the package code indicates RoHS status only. Package drawings may show a different suffix character, but the drawing pertains to the package regardless of RoHS status.Package thermal resistances were obtained using the method described in JEDEC specification JESD51-7, using a four-layer board. For detailed information on package thermal considerations, refer to /thermal-tutorial .MAX33250E/MAX33251E600V Isolated 2Tx/2Rx and 1Tx/1Rx RS-232Transceiver with ±15kV ESD and Integrated CapacitorsElectrical Characteristics(V CCA -V GNDA =3.0V to 5.5V,V CCB -V GNDB =3.0V to 5.5V,T A =T MIN to T MAX ,unless otherwise noted.Typical values are at V CCA -V GNDA =3.3V,V CCB -V GNDB =3.3V,V GNDA =V GNDB ,and T A =+25°C.(Note 1),Limits are 100%tested at T A =+25°C.Limits over the operating temperature range and relevant supply voltage range are guaranteed by design and characterization.Specifications marked "GBD" are guaranteed by design and not production tested.)PARAMETER SYMBOLCONDITIONSMINTYPMAXUNITSPOWER Supply VoltageV CCA , V CCB3.05.5VSupply CurrentI CCAV CCA = 5V, R_IN and T_IN idle 12mA V CCA = 3.3V, R_IN and T_IN idle 10I CCBV CCB = 5V, R_IN and T_IN idle, no load 12V CCB = 3.3V, R_IN and T_IN idle, no load10Undervoltage-Lockout ThresholdV UVLO V CCA - V GNDA (Note 2) 2.0V Undervoltage-Lockout HysteresisV UVLOHYSV CCA - V GNDA (Note 2)0.1V INPUT INTERFACE (T_IN, R_IN)Input Low VoltageV ILT_IN relative to GNDA0.8VR_IN relative to GNDB, T A = 25ºC,V CC = 3.3V0.6R_IN relative to GNDB, T A = 25ºC,V CC = 5V0.8Input High VoltageV IHT_IN relative to GNDA0.7 x V CCA VR_IN relative to GNDB, V CCB = 3.3V and 5V, T A = 25°C 2.4Transmitter Input Hysteresis (T_IN)0.5V Receiver Input Hysteresis (R_IN)0.5V Transmitter Input Leakage(T_IN)±1μA Input Resistance (R_IN)T A = 25ºC357kΩRECEIVER OUTPUT INTERFACE (R_OUT)Output Low Voltage V OL R_OUT relative to GNDA,sink current = 4mA 0.8V Output High Voltage V OHR_OUT relative to GNDA,source current = 4mAV CCA -0.4V Output Short-Circuit Current±110mATRANSMITTER OUTPUT (T_OUT)Output Voltage SwingT_OUT loaded with 3kΩ to GNDB±5VMAX33250E/MAX33251E600V Isolated 2Tx/2Rx and 1Tx/1Rx RS-232Transceiver with ±15kV ESD and Integrated CapacitorsElectrical Characteristics (continued)(V CCA -V GNDA =3.0V to 5.5V,V CCB -V GNDB =3.0V to 5.5V,T A =T MIN to T MAX ,unless otherwise noted.Typical values are at V CCA -V GNDA =3.3V,V CCB -V GNDB =3.3V,V GNDA =V GNDB ,and T A =+25°C.(Note 1),Limits are 100%tested at T A =+25°C.Limits over the operating temperature range and relevant supply voltage range are guaranteed by design and characterization.Specifications marked "GBD" are guaranteed by design and not production tested.)PARAMETER SYMBOLCONDITIONSMIN TYP MAXUNITS Output Resistance V CCB = 0V,transmitters = ±2V30010MΩOutput Short-Circuit Current±70mA Output Leakage CurrentV CCB = 0V, V OUT =±12V±25μAESD AND ISOLATION PROTECTIONESD for R_IN, T_OUTIEC 61000-4-2 Air Discharge±12kVIEC 61000-4-2 Contact Discharge ±6ESD Human Body Model JEDEC JS-001-2014±15Isolation Voltage V ISO t = 60s (Note 3)600V RMS Working Isolation VoltageV IOWM> 50 years (Note 3)200V RMS TIMING CHARACTERISTICS Maximum Data Rate V CCB = 5V, R L = 3kΩ, C L = 1000pF 1000kbps Receiver Propagation Delayt PHL , t PLH R_IN to R_OUT, C L = 150pF0.15μs Transmitter Skew | t PHL - t PLH |(Note 4)35ns Receiver Skew | t PHL - t PLH |60ns Transition-Region Slew RateV CCA = V CCB = 3.3V, T A = +25C, R L =3k to 7k, C L = 150pF to 1000pF,measured from +3V to -3V or -3V to +3V24150V/μsNote 1:All units are production tested at T A =25°C.Specifications over temperature are guaranteed by design.All voltages of side Aare referenced to GNDA. All voltages of side B are referenced to GNDB.Note 2:The undervoltage lockout threshold and hysteresis guarantee that the outputs are in a known state when the supply voltagedips.Note 3:The isolation is guaranteed by design and not production tested.Note 4:Transmitter skew is measured at the transmitter zero cross points.MAX33250E/MAX33251E600V Isolated 2Tx/2Rx and 1Tx/1Rx RS-232Transceiver with ±15kV ESD and Integrated CapacitorsTypical Operating Characteristics (V DD= 5V, V L= 3.3V, R L= 60Ω, C L= 15pF, T A= +25°C, unless otherwise noted.)MAX33250E/MAX33251E600V Isolated 2Tx/2Rx and 1Tx/1Rx RS-232Transceiver with ±15kV ESDand Integrated CapacitorsTypical Operating Characteristics (continued) (V DD= 5V, V L= 3.3V, R L= 60Ω, C L= 15pF, T A= +25°C, unless otherwise noted.)MAX33250E/MAX33251E600V Isolated 2Tx/2Rx and 1Tx/1Rx RS-232Transceiver with ±15kV ESDand Integrated CapacitorsMAX33250E/MAX33251E600V Isolated 2Tx/2Rx and 1Tx/1Rx RS-232Transceiver with ±15kV ESDand Integrated Capacitors Pin ConfigurationsPin DescriptionPINNAME FUNCTIONMAX33250EMAX33251E11V CCA Supply Voltage of Logic Side A. Bypass V CCA with a 0.1μF ceramic capacitor to GNDA 22T1IN TTL/CMOS Transmitter Input 13---T2IN TTL/CMOS Transmitter Input 244R1OUT TTL/CMOS Receiver Output 15---R2OUT TTL/CMOS Receiver Output 266GNDA Ground for Logic Side A 77GNDB Ground for Field Side B 8---R2IN RS-232 Receiver Input 299R1IN RS-232 Receiver Input 110---T2OUT RS-232 Transmitter Output 21111T1OUT RS-232 Transmitter Output 11212V CCBSupply Voltage of Logic Side B. Bypass V CCB with a 0.1μF ceramic capacitor to GNDBMAX33250E/MAX33251E600V Isolated 2Tx/2Rx and 1Tx/1Rx RS-232Transceiver with ±15kV ESD and Integrated CapacitorsMAX33250E/MAX33251E600V Isolated 2Tx/2Rx and 1Tx/1Rx RS-232Transceiver with ±15kV ESDand Integrated Capacitors Detailed DescriptionThe MAX33250E and MAX33251E are1Mbps,600V RMS isolated RS-232transceivers.The MAX33250E has2 transmitters and2receivers(2Tx/2Rx),and the MAX33251E has1transmitter and1receiver(1Tx/1Rx).The isolation is provided by Maxim’s proprietary insulation material that can withstand600V RMS for60seconds.The MAX33250E and MAX33251E conform to the EIA/TIA-232standard and operates at data rates up to1Mbps over the temperature range of -40ºC to 85ºC.Digital IsolationThe MAX33250E and MAX33251E provide galvanic isolation and protection for digital signals from the local microcontroller’s logic UART port(primary side)to the field lines(secondary side).A capacitive design is utilized where the insulation material for the isolation barrier is rated for600V RMS withstand voltage(V ISO)for60seconds.The same material can also be exposed to a differential of200V RMS of working voltage(V IOWM)for more than50years,providing longevity for many different types of end equipment.The isolation barrier also breaks ground loops and level translation for two different systems where it could potentially create inadvertent or misinterpret data signals.Dual Charge Pump Voltage Converter and InverterBoth parts have internal RS-232power supplies that consist of a regulated dual charge pump that provides output voltages of+5.5V(doubling charge pump)and-5.5V(inverting charge pump),over the+3.0V to+5.5V range.Each charge pump is internally connected to a pair of flying capacitors and a pair of reservoir capacitors to generate the internal V+ and V- supplies, as shown in Typical Application Diagram.Startup and Undervoltage LockoutThe V CCA and V CCB supplies are both internally monitored for undervoltage conditions.Undervoltage events can occur during power-up,power-down,or during normal operation due to a dip in either power supply line.When an undervoltage event is detected on either of the supplies,all outputs on both sides are automatically controlled,regardless of the status of the inputs.Table 1. Output Control Truth TableINPUTS V CCA V CCB RxOUT TxOUT RxIN = 1Undervoltage Powered High---RxIN = 0Undervoltage Powered Follows V CCA---TxIN = 1Undervoltage Powered—LowTxIN = 0Undervoltage Powered—LowRxIN = 1Powered Undervoltage High---RxIN = 0Powered Undervoltage High---TxIN = 1Powered Undervoltage—*LowTxIN = 0Powered Undervoltage—*Low*TxOUT will be out of compliance with the RS-232 specification as V CCB falls below 2.9V.Transceiver with ±15kV ESDand Integrated CapacitorsRS-232 TransmittersThe transmitters are inverting level translators that convert CMOS-logic levels from the UART or equivalent output port to+5V EIA/TIA-232levels.The two devices guarantee1Mbps with worst-case loads of3kΩin parallel with1000pF, providing compatibility with PC-to-PC communication software.Transmitters can be paralleled to drive multiple receivers. RS-232 ReceiversThe receivers convert RS-232signals to CMOS-logic output levels to the UART or equivalent input port.The devices feature inverting outputs that always remain active.Power Supply DecouplingTo reduce ripple and the chance of introducing data errors,bypass V CCA and V CCB with0.1μF ceramic capacitors to GNDA and GNDB, respectively. Place the bypass capacitors as close to the power-supply input pins as possible.Insulation and Safety CharacteristicsPARAMETERSYMBOL CONDITIONSVALUE UNIT IEC INSULATION AND SAFETY RELATED FOR SPECIFICATIONSExternal Tracking (Creepage)CPG IEC 60664-1 4.4mm External Air Gap (Clearance)CLRIEC 60664-1 4.4mm Minimum Internal Gap Insulation Thickness 0.0026mm Tracking Resistance(Comparative Tracking Index)CTI IEC 112/VDE 030 Part 1175V Insulation Resistance Across Barrier R ISO 1GΩCapacitance Across Isolation BarrierC IOf = 1MHz12pFVDE IEC INSULATION CHARACTERISTICS Surge Isolation VoltageV IOSM IEC 60747-17,section 5.3.1.6and 5.4.6for basic insulation1kV PEAK Repetitive Peak Isolation Voltage V IORM IEC 60747-17, section 5.3.1.3282kV PEAK Rated Transient Isolation Voltage V IOTM IEC 60747-17, section 5.3.1.4850kV PEAK Safety Limiting Temperature T S IEC 60747-17, section 7.2.1150°C Safety Limiting SideAPowerDissipation P SAIEC 60747-17, section 7.2.10.75WSafety Limiting Side B PowerDissipationP SB IEC 60747-17, section 7.2.10.75W Apparent Charge Method q pdIEC 60747-17, section 7.4 method a and b 5pC Overvoltage Category IEC 60664-1, single or three phase 50V DC or AC I,II —Overvoltage Category IEC 60664-1,single or three phase 100V DC or AC I —Climatic Category 40/125/21—Pollution DegreeDIN VDE 01102—Transceiver with ±15kV ESD and Integrated CapacitorsTransceiver with ±15kV ESDand Integrated Capacitors Typical Application CircuitOrdering InformationPART NUMBER TEMPERATURERANGE CHANNEL-CONFIGURATION DATA RATE PIN-PACKAGE MAX33250EELC+-40°C to +85°C 2 Transmitters, 2 Receivers 1Mbps 12 (6mm x 6mm) LGA MAX33251EELC+-40°C to +85°C1 Transmitter, 1 Receiver1Mbps12 (6mm x 6mm) LGA+Denotes a lead(Pb)-free/RoHS-compliant package.T = Tape-and-reel.Transceiver with ±15kV ESD and Integrated CapacitorsRevision HistoryREVISION NUMBERREVISION DATE DESCRIPTIONPAGES CHANGED09/18Initial release—111/18Updated Ordering Information13For pricing, delivery, and ordering information, please visit Maxim Integrated’s online storefront at https:///en/storefront/storefront.html.Maxim Integrated cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim Integrated product. No circuit patentlicenses are implied. Maxim Integrated reserves the right to change the circuitry and specifications without notice at any time. The parametric values (min and max limits) shown in the Electrical Characteristics table are guaranteed. Other parametric values quoted in this data sheet are provided for guidance.Transceiver with ±15kV ESD and Integrated CapacitorsMAX33251EELC+。
MAX232 与 MAX3232 外部电路电容
MAX232 与MAX3232 外部电路电容
这几天开始忙于调试我们自己的STM32 主板，2.4G RF 模块已经调试成功，然后接着调试串口，也就是如此，问题来了。
我们的主板是按照神舟IV 板上的原理图进行扩展和延伸，串口电路图自然和神舟IV 板上的同一类型MAX3232。
我们在网上采购的芯片是MAX232，一开始都没有注意，
调试程序时发现不论什幺波特率，串口调试助手都能收到数据，但数据都
是错误的。
而同样的代码放在神舟IV 板上，两个串口都能正常工作。
很明显可以断定是我们
板子的问题。
于是连夜加班查找问题，电路重新检查过，我们板上使用的是串口1，对
应IO 口为PA9、PA10。
电压也测过是一样的，唯一当时没有怀疑过的就是外设电容。
直到今天
早上，我仍然在怀疑是串口芯片坏了。
也就是这个时候，脑海中突然灵光
一现，我们焊接的串口芯片和神舟IV 上的是不是一样的呢? 赶忙拿起来一看，不一致，看起来
似乎区别也不大，就名字不一样。
翻开手册，看到手册上描述的外部电容。
中文芯片手册MAX3222EMAX3232EMAX3237EMAX3241EMAX3246E
MAX3222E/MAX3232E/MAX3237E/MAX3241E†/ MAX3246E的中文芯片手册±15kV ESD保护，电流低至10nA，3.0V至5.5V，高达1Mbps，的RS-232收发器概述该MAX3222E/MAX3232E/MAX3237E/MAX3241E /MAX3246E +3.0 V供电EIA/TIA-232和V.28/V.24通信接口器件具有低功耗，高数据速率的能力，以及增强的静电放电（ESD）保护。
增强型ESD结构保护所有发送器输出和接收器输入采用IEC 1000-4-2气隙放电，±8kV使用IEC 1000-4-2接触放电（MAX3246E为±9kV ），±15kV使用人体模型。
基于上述标准，MAX3237E的逻辑和接收I / O 引脚将被保护，而发射机输出引脚的保护利用人体模型±15kV的。
一个专有的低压差发送器输出级可以提供+3.0 V至+5.5 V电源真正的RS -232性能，利用内部双电荷泵。
充电泵仅需要四个工作在+3.3 V电源的0.1μF的小电容。
每款器件保证工作在250kbps数据速率下维持RS - 232输出电平。
该MAX3237E保证操作在250kbps在正常工作模式和1Mbps的中MegaBaud™工作模式，同时保持RS- 232兼容的输出电平。
MAX3222E/MAX3232E包括两个接收器和两个发射器。
MAX3222E具有1μA关断模式，可降低功耗的电池供电的便携式系统。
该MAX3222E接收器仍活跃在关断模式下，允许监控外部设备的同时仅需耗电1μA供应电流。
TheMAX3222E和MAX3232E的引脚，封装，并与业界标准的MAX242和MAX232，分别为功能兼容。
该MAX3241E/MAX3246E是专为笔记本电脑和小型笔记本电脑设计完整串口（3个驱动器/5个接收器）。
该MAX3237E（5驱动器/ 三个接收器），非常适合那些需要快速数据传输的外围设备。
立创商城自制低成本串口转以太网网关
自制低成本串口转以太网网关1、作品简介串口转以太网网关可以将串口的数据转发到网络上特定服务器的特定端口 上，实现设备的远程控制、数据的远程传输，现在已经广泛应用于人们的生产生 活中了，但是目前价格普遍偏高。
我设计了一种低成本（约 50 元）的串口转以 太网网关方案， 性能和可靠性能与商业串口转以太网网关相媲美，成本降低一多 半，值得推广。
我承诺，本系统所有资料全部开源。
很多人问我作品的创新点在哪里，我说没有创新点，这个产品市场上已经很 多了，然后别人说没有创新点那么做这个有啥意义。
这里我想说的是，虽然市场 上有很多这样的设备，但那毕竟是别人的，或许我自己做的东西没有别人的好， 但那毕竟是属于自己的， 以后当需要这个设备的时候就不用低三下四的从别人那 里购买了。
2、系统架构系统架构图如图 2.1 所示。
ZigBee模块座 （预留）UART串口 MAX3232UARTMCU STM32F103C8UARTSPI以太网 W5500GPRS SIM800C （预留）图 2.1 串口转以太网网关架构图系统由五大部分组成：MAX3232 模块、ZigBee 模块座、SIM800C 模块、以太网模块、MCU 组成，其中 ZigBee 模块座和 SIM800C 模块为预留，可以暂不 焊接。
MCU 外围的这四种模块之间均可以实现相互通信，可以通过程序设置成 “串口 GPRS 网关”、“ZigBee 以太网网关”等等。
3、部分原理图（如需原理图和 PCB 可联系立创商城）3.1 电源部分电路 电源部分框图如图 3.1 所示。
外部12V输入 TPS5430 4.1V 4.1V 4.1V 4.1V 3.3V 3.3V 3.3V SIM800C供电 SP6205 SP6205 SP6205 MCU及外围 器件供电 W5500以太 网模块供电 ZigBee模块 供电图 3.1 系统电源 Tree主供电芯片为德州仪器 TPS5430 电源芯片， 5.5~36V 输入， 3A 输出， 500kHz， 性能稳定，应用广泛。
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PACKAGING INFORMATIONOrderable Device Status(1)PackageType PackageDrawingPins PackageQtyEco Plan(2)Lead/Ball Finish MSL Peak Temp(3)MAX3232CD ACTIVE SOIC D1640Green(RoHS&no Sb/Br)CU NIPDAU Level-1-260C-UNLIMMAX3232CDB ACTIVE SSOP DB1680Green(RoHS&no Sb/Br)CU NIPDAU Level-1-260C-UNLIMMAX3232CDBE4ACTIVE SSOP DB1680Green(RoHS&no Sb/Br)CU NIPDAU Level-1-260C-UNLIMMAX3232CDBR ACTIVE SSOP DB162000Green(RoHS&no Sb/Br)CU NIPDAU Level-1-260C-UNLIMMAX3232CDBRE4ACTIVE SSOP DB162000Green(RoHS&no Sb/Br)CU NIPDAU Level-1-260C-UNLIMMAX3232CDE4ACTIVE SOIC D1640Green(RoHS&no Sb/Br)CU NIPDAU Level-1-260C-UNLIMMAX3232CDR ACTIVE SOIC D162500Green(RoHS&no Sb/Br)CU NIPDAU Level-1-260C-UNLIMMAX3232CDRE4ACTIVE SOIC D162500Green(RoHS&no Sb/Br)CU NIPDAU Level-1-260C-UNLIMMAX3232CDW ACTIVE SOIC DW1640Green(RoHS&no Sb/Br)CU NIPDAU Level-1-260C-UNLIMMAX3232CDWG4ACTIVE SOIC DW1640Green(RoHS&no Sb/Br)CU NIPDAU Level-1-260C-UNLIMMAX3232CDWR ACTIVE SOIC DW162000Green(RoHS&no Sb/Br)CU NIPDAU Level-1-260C-UNLIMMAX3232CDWRG4ACTIVE SOIC DW162000Green(RoHS&no Sb/Br)CU NIPDAU Level-1-260C-UNLIMMAX3232CPW ACTIVE TSSOP PW1690Green(RoHS&no Sb/Br)CU NIPDAU Level-1-260C-UNLIMMAX3232CPWE4ACTIVE TSSOP PW1690Green(RoHS&no Sb/Br)CU NIPDAU Level-1-260C-UNLIMMAX3232CPWG4ACTIVE TSSOP PW1690Green(RoHS&no Sb/Br)CU NIPDAU Level-1-260C-UNLIMMAX3232CPWR ACTIVE TSSOP PW162000Green(RoHS&no Sb/Br)CU NIPDAU Level-1-260C-UNLIMMAX3232CPWRE4ACTIVE TSSOP PW162000Green(RoHS&no Sb/Br)CU NIPDAU Level-1-260C-UNLIMMAX3232CPWRG4ACTIVE TSSOP PW162000Green(RoHS&no Sb/Br)CU NIPDAU Level-1-260C-UNLIMMAX3232ID ACTIVE SOIC D1640Green(RoHS&no Sb/Br)CU NIPDAU Level-1-260C-UNLIMMAX3232IDB ACTIVE SSOP DB1680Green(RoHS&no Sb/Br)CU NIPDAU Level-1-260C-UNLIMMAX3232IDBE4ACTIVE SSOP DB1680Green(RoHS&no Sb/Br)CU NIPDAU Level-1-260C-UNLIMMAX3232IDBR ACTIVE SSOP DB162000Green(RoHS&no Sb/Br)CU NIPDAU Level-1-260C-UNLIMMAX3232IDBRE4ACTIVE SSOP DB162000Green(RoHS&no Sb/Br)CU NIPDAU Level-1-260C-UNLIMMAX3232IDE4ACTIVE SOIC D1640Green(RoHS&no Sb/Br)CU NIPDAU Level-1-260C-UNLIMMAX3232IDR ACTIVE SOIC D162500Green(RoHS&no Sb/Br)CU NIPDAU Level-1-260C-UNLIMOrderable Device Status(1)PackageType PackageDrawingPins PackageQtyEco Plan(2)Lead/Ball Finish MSL Peak Temp(3)MAX3232IDRE4ACTIVE SOIC D162500Green(RoHS&no Sb/Br)CU NIPDAU Level-1-260C-UNLIMMAX3232IDW ACTIVE SOIC DW1640Green(RoHS&no Sb/Br)CU NIPDAU Level-1-260C-UNLIMMAX3232IDWE4ACTIVE SOIC DW1640Green(RoHS&no Sb/Br)CU NIPDAU Level-1-260C-UNLIMMAX3232IDWR ACTIVE SOIC DW162000Green(RoHS&no Sb/Br)CU NIPDAU Level-1-260C-UNLIMMAX3232IDWRE4ACTIVE SOIC DW162000Green(RoHS&no Sb/Br)CU NIPDAU Level-1-260C-UNLIMMAX3232IPW ACTIVE TSSOP PW1690Green(RoHS&no Sb/Br)CU NIPDAU Level-1-260C-UNLIMMAX3232IPWE4ACTIVE TSSOP PW1690Green(RoHS&no Sb/Br)CU NIPDAU Level-1-260C-UNLIMMAX3232IPWR ACTIVE TSSOP PW162000Green(RoHS&no Sb/Br)CU NIPDAU Level-1-260C-UNLIMMAX3232IPWRE4ACTIVE TSSOP PW162000Green(RoHS&no Sb/Br)CU NIPDAU Level-1-260C-UNLIM(1)The marketing status values are defined as follows:ACTIVE:Product device recommended for new designs.LIFEBUY:TI has announced that the device will be discontinued,and a lifetime-buy period is in effect.NRND:Not recommended for new designs.Device is in production to support existing customers,but TI does not recommend using this part in a new design.PREVIEW:Device has been announced but is not in production.Samples may or may not be available.OBSOLETE:TI has discontinued the production of the device.(2)Eco Plan-The planned eco-friendly classification:Pb-Free(RoHS),Pb-Free(RoHS Exempt),or Green(RoHS&no Sb/Br)-please check /productcontent for the latest availability information and additional product content details.TBD:The Pb-Free/Green conversion plan has not been defined.Pb-Free(RoHS):TI's terms"Lead-Free"or"Pb-Free"mean semiconductor products that are compatible with the current RoHS requirements for all6substances,including the requirement that lead not exceed0.1%by weight in homogeneous materials.Where designed to be soldered at high temperatures,TI Pb-Free products are suitable for use in specified lead-free processes.Pb-Free(RoHS Exempt):This component has a RoHS exemption for either1)lead-based flip-chip solder bumps used between the die and package,or2)lead-based die adhesive used between the die and leadframe.The component is otherwise considered Pb-Free(RoHS compatible)as defined above.Green(RoHS&no Sb/Br):TI defines"Green"to mean Pb-Free(RoHS compatible),and free of Bromine(Br)and Antimony(Sb)based flame retardants(Br or Sb do not exceed0.1%by weight in homogeneous material)(3)MSL,Peak Temp.--The Moisture Sensitivity Level rating according to the JEDEC industry standard classifications,and peak solder temperature.Important Information and Disclaimer:The information provided on this page represents TI's knowledge and belief as of the date that it is provided.TI bases its knowledge and belief on information provided by third parties,and makes no representation or warranty as to the accuracy of 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