直流电机驱动芯片L293与L298

【简要说明】一、尺寸：长71mmX宽43mmX高28mm二、主要芯片：L297、L298N三、工作电压：控制信号直流4.5~5.5V；电机电压直流5V~30V四、最大工作电流：2A五、额定功率25W六、特点：1、具有电源指示。

2、转速可调3、抗干扰能力强4、具有续流保护和过电流保护5、可单独控制一台步进电机6、可控制两相和四相步进电机7、可控制直径在42mm内的任何，两相和四相步进电机适用场合：单片机学习、电子竞赛、产品开发、毕业设计。

【标注图片】【步进电机控制接线图】步进电机的控制实例步进电机是数字控制电机，它将脉冲信号转变成角位移，即给一个脉冲信号，步进电机就转动一个角度，因此非常适合于单片机控制。

步进电机可分为反应式步进电机（简称VR）、永磁式步进电机（简称PM）和混合式步进电机（简称HB）。

一、步进电机最大特点是：1、它是通过输入脉冲信号来进行控制的。

2、电机的总转动角度由输入脉冲数决定。

3、电机的转速由脉冲信号频率决定。

二、步进电机的驱动电路根据控制信号工作，控制信号由单片机产生。

(或者其他信号源)三、控制步进电机的速度如果给步进电机发一个控制脉冲，它就转一步，再发一个脉冲，它会再转一步。

两个脉冲的间隔越短，步进电机就转得越快。

调整单片机发出的脉冲频率，就可以对步进电机进行调速。

（注意：如果脉冲频率的速度大于了电机的反应速度，那么步进电机将会出现失步现象）。

四、此板驱动步进电机测试程序说明：以AT89S52单片机控制单元，C语言编程！【接线图】【测试程序】/********************************************************************汇诚科技实现功能:正转_反转_减速_加速程序使用芯片：AT89S52 或者STC89C52晶振：11.0592MHZ编译环境：Keil作者：zhangxinchun淘宝店：汇诚科技【声明】此程序仅用于学习与参考，引用请注明和作者信息！*********************************************************************/ #include<reg52.h>#define uchar unsigned char#define uint unsigned intuchar Y=1; //初始化速度/********************************************************控制位定义********************************************************/sbit shi_neng=P1^0; // 使能控制位sbit fang_shi=P1^1; // 工作方式控制位sbit fang_xiang=P1^2;// 旋转方向控制位sbit mai_chong=P1^3; // 脉冲控制位sbit zheng_zhuan=P2^0; // 正转sbit fan_zhuan=P2^1; // 反转sbit jia_su=P2^2; // 加速sbit jian_su=P2^3; // 减速/********************************************************延时函数********************************************************/ void delay(uchar i)//延时函数{uchar j,k;for(j=0;j<i;j++)for(k=0;k<180;k++);}/********************************************************加速函数********************************************************/ void jia(){Y=Y-1;if(Y<=1){Y=1;}//如果速度值小于等于1，值保持不变}/********************************************************减速函数********************************************************/ void jian(){Y=Y+1;if(Y>=100){Y=100;}}/********************************************************主函数********************************************************/main(){shi_neng=1; // 使能控制位fang_shi=1; // 工作方式控制位fang_xiang=1;// 旋转方向控制位mai_chong=1; // 脉冲控制位while(1){if(zheng_zhuan==0){fang_xiang=1;}if(fan_zhuan==0){fang_xiang=0;}if(jia_su==0){delay(10);while(!jia_su);jia();}if(jian_su==0){delay(10);while(!jian_su);jian();}mai_chong=~mai_chong; //输出时钟脉冲delay(Y); //延时(括号内数值越小，电机转动速度越快)}}/********************************************************结束********************************************************/【应用原理图】L297_L298芯片混合式步进电机驱动器元件清单序号名称标注名型号封装备注1 电阻R1、R3 1K 贴片0805封装2 电阻R2 3.9K 贴片0805封装3 电阻R4、R5 0.5欧姆直插2W4 电阻R6 22K 贴片0805封装5 电容C1 25V0.22uf 直插电容6 电阻C2 50V100UF 电解电容7 发个二极管DS1 红色二极管区分正负极8 整流二极管D1~D8 IN40079 芯片U1 L297 20P直插10 芯片U2 L29811 排针P1 6针12 端子6针【图片展示】/********************************************************实现功能：正转程序使用芯片：AT89S52晶振：11.0592MHZ编译环境：Keil********************************************************/#include<reg52.h> //库文件#define uchar unsigned char //字符型宏定义#define uint unsigned int //整型宏定义uchar tt; //定时器计数初值定义uint sec; //速度值定义uchar Y=30; //初始化速度/********************************************************控制位定义********************************************************/sbit shi_neng=P1^0; // 使能控制位sbit fang_shi=P1^1; // 工作方式控制位sbit fang_xiang=P1^2;// 旋转方向控制位sbit mai_chong=P1^3; // 脉冲控制位sbit zheng_zhuan=P2^0; // 正转sbit fan_zhuan=P2^1; // 反转sbit jia_su=P2^2; // 加速sbit jian_su=P2^3; // 减速/********************************************************************延时函数*********************************************************************/ void delay(uchar t){uchar i,j;for(i=0;i<t;i++){for(j=13;j>0;j--);{ ;}}}/********************************************************************定时中断服务函数*********************************************************************/ void t0(void) interrupt 1 using 0 //定时中断服务函数{tt++; //每过250ust tt 加一if(tt==1) //当tt满足条件时{tt=0; //计满重新再计sec++;if(sec==Y) //括号内数值越小，电机转动速度越快{sec=0; //计满重新再计mai_chong=~mai_chong; //脉冲输出}}}/********************************************************初始化********************************************************/ void init(){TMOD=0x02; //定时器工作在方式2ET0=1;EA=1;TH0=0xFF; //对TH0 TL0 赋值TL0=0xFE;TR0=1; //开始定时sec=0;mai_chong=1; // 脉冲控制位}/********************************************************加速函数********************************************************/ void jia(){Y=Y-2;if(Y<=1){Y=2;}//如果速度值小于等于1，值保持不变}/********************************************************减速函数********************************************************/ void jian(){Y=Y+2;if(Y>=100){Y=100;}}/********************************************************主函数********************************************************/main(){init(); //程序初始化shi_neng=0; // 使能控制位fang_shi=1; // 工作方式控制fang_xiang=1;// 控制方向为正转while(1){if(zheng_zhuan==0){delay(100);shi_neng=1;fang_xiang=0;}if(fan_zhuan==0){delay(100);shi_neng=1;fang_xiang=1;}if(jia_su==0){delay(10);while(!jia_su);jia();}if(jian_su==0){delay(10);while(!jian_su);jian();}}}/********************************************************结束********************************************************/keil参考程序正转_反转_加速_减速_高速#include<reg52.h>#define uchar unsigned char#define uint unsigned intuchar Y=1; //初始化速度/********************************************************控制位定义********************************************************/sbit shi_neng=P1^0; // 使能控制位sbit fang_shi=P1^1; // 工作方式控制位sbit fang_xiang=P1^2;// 旋转方向控制位sbit mai_chong=P1^3; // 脉冲控制位sbit zheng_zhuan=P2^0; // 正转sbit fan_zhuan=P2^1; // 反转sbit jia_su=P2^2; // 加速sbit jian_su=P2^3; // 减速/********************************************************延时函数********************************************************/void delay(uchar i)//延时函数{uchar j,k;for(j=0;j<i;j++)for(k=0;k<180;k++);}/********************************************************加速函数********************************************************/ void jia(){Y=Y-1;if(Y<=1){Y=1;}//如果速度值小于等于1，值保持不变}/********************************************************减速函数********************************************************/ void jian(){Y=Y+1;if(Y>=100){Y=100;}}/********************************************************主函数********************************************************/main(){shi_neng=1; // 使能控制位fang_shi=1; // 工作方式控制位fang_xiang=1;// 旋转方向控制位mai_chong=1; // 脉冲控制位while(1){if(zheng_zhuan==0){fang_xiang=1;}if(fan_zhuan==0){fang_xiang=0;}if(jia_su==0){delay(10);while(!jia_su);jia();}if(jian_su==0){delay(10);while(!jian_su);jian();}mai_chong=~mai_chong; //输出时钟脉冲delay(Y); //延时(括号内数值越小，电机转动速度越快)}}AVR系列单片机控制参考程序#include <iom16v.h>#include <macros.h>/**********************************************************************函数数据类型说明**********************************************************************/ #define uchar unsigned char#define uint unsigned int/**********************************************************************延时函数**********************************************************************/ void delay(uint MS){uint i,j;for( i=0;i<MS;i++)for(j=0;j<80;j++); //1141是在8MHz晶振下，通过软件仿真反复实验得到的数值}/**********************************************************************主函数**********************************************************************/ void main(){ uint i;i=10;//改变变量i 的大小可以改变速度，i越大速度越慢DDRB=0XFF;//PORTC=0XFF;PORTB|=BIT(0);//00000001 使能控制开PORTB|=BIT(1);//00000010 四拍工作方式PORTB|=BIT(2);//00000100 正方向旋转while(1){PORTB|=BIT(3);//00001000 脉冲输出delay(i);PORTB&=~BIT(3);delay(i);}}/**********************************************************************结束**********************************************************************/。

APPLICATION NOTEAN238/0488EASE STEPPER-MOTOR-DRIVE DESIGNHIGH-POWER,DUAL-BRIDGE ICsIn addition to simplifying design problems,a family of dedicated chips improves stepper-motor drive-circuit reliability by significantly reducing the component count.Figure 1:The Simplest Stepper-motor Drive Technique is the Basic L/R Configuration.Adding Series Re-sistors and Raising the Supply to Make an L/4R Drive Improves Torque at High Steps rates but Reduces Efficiency.The L293,L293E and L298N dual-bridge ICs (see box ,”inside the dual-bridge ICs”)significantly redu-ce the problems encountered in the design of step-per-motor drive circuitry.They can,for example,simplify the design and increase the efficiency ofconstant-current choppers.And with a single chip replacing the transistors and predriver stages,cir-cuit performance improves.Best of all,the devices have applications in complex as well as basic driver networks.1/8SIMPLEST DESIGN IS AN L/R DRIVE The simplest motor-drive configuration (fig.1)con-sists of a µC that performs the translator function in software (see box ,”Generating switching sequen-ces”)and drives the motor through a L293dual brid-ge.Only eight external components are required ;these are diodes that protect the device’s output transistors againstinductive spikes generatedwhen a winding de-energizes.The L293handles 1A continuous(for higher currentuse and L298N).However,if you plan to run the mo-tor continuously with two phases on,dissipation will be the limiting factor.You can improve the performance of this basic L/R drive by increasing the series resistanceand raising the supply voltage to restore the original phase cur-rent.At high speeds,torque improves,but efficiency decreases.Normally,you increase each winding’s resistance by a factor of four through the addition of a 3R series resistance,resulting in the L/4R drive.Dual-bridge driver ICs reducethe partscount ofbipolar steppermotors andsimplify design.The sche-matic of the L298N is functionally similar to those of the L293and L293E.INSIDE THE DUAL-BRIDGE ICsThe L293,L293E and L298N (figure)contain two po-wer-transistor bridges,predriver stages,control logic and protection circuitry.There’s a control input for each bridge and an enable input for each half bridge ;inputs connect directly to µCs,CMOS or TTL.The ICs inte-grate level shifters with a separate logic-supply pin.For current sensing,the L293E and L298N have external emitter connections.A single package drives a 2-phase bipolar stepper mo-tor,challenging the assumption held by many that uni-polar motors are easier to drive.You can use a bipolar motor -simpler and less expen-sive than a unipolar motor -without building complex power stages.Furthermore,you don’t have to worry about simultaneous conduction of a half bridge’s sour-ce and sink transistors -a basic problem with discrete-component bridge circuits.Chip design makes it impossible for both transistors to be on at the same time.Designers should also discard the mistaken idea that constant-current chopper drivers are complicated and expensive.You can build one with two bridge ICs and a few passive components.Type I O I O(PEA K)V S Package Sensing Connections L2931A 1.5A 36V DIP16L293E 1A 1.5A 36V DIP20One per Half Bridge L298N2A2.5A46VMultiwatt15One per BridgeAPPLICATION NOTE2/8MULTIPLE SUPPLIES BOOST PERFOR-MANCEA dual-level supply also improves the performance of a basic L/R circuit.A high supply voltage yields good torque characteristics when the motor is run-ning.A lower-than-rated voltage provides some hol-ding torque when the motor is at rest,therebysaving power when the motor is idle.Fig.2shows a suitable voltage-switch circuit.R x sets the holding current,which can be low because a permanent magnet or hybrid stepper motor provi-des some holding torque at zero current.However, make certain the L293’s motor-supply input never goes below the logic-supply voltage.While there’s no danger of damaging the device,it’s imposssible to drive the output transistors correctly under such conditions.The dual bridge’s enable inputs offera meansof ex-tending the chip’s flexibility.For example,you can connect them directly to the logic supply-no resi-stors are needed-to enable the chip permanently. As an alternative,use the enable inputs to disable the motor during the power-on reset sequence.In wave-drive and half-step modes,use the enable inputs to increase torque at high speeds.When a winding de-energizes,flux collapse is a function of the current-decay rate.During this decay,the de-energized winding opposes the efforts of the next winding in sequence,partially cancelling the torque.You can minimize this effect by disabling a bridge only when the winding it drives is turned off;becau-se the∆i/∆t of an inductor equals E/L,disabling the bridge acceleratesthe current decay.This action di-scharges the winding’s stored energy through its supply and maintains the terminal voltage E at V s plus two diode drops.If you were to leave the bridge enabled,the current would flow to ground through one diode and one transistor,and it would lower the terminalvoltage.This scheme doesn’t applywith dri-veswithtwophaseson becauseno winding ever de-energizes.Figure2:Switching the Supply to a Lower Volt-age when the Motor is Idle Saves Cur-rent without Compromising DrivingPower.Figure3:Maintaining a Constant-average Phase Current this Fixed-ripple Chopper Provides Improved Performance and Efficiency V REF Controls the Phase Current.APPLICATION NOTE3/8GENERATING SWITCHING SEQUENCESIn addition to selecting a motor and determining power-stage design,you must also decide how to generate the switchingsequences thatstepthe motor.Programming a µC or using a special piece of hardware called a tran-sistor accomplishes this task.Software translation is more economical,and it is the first choice for large-volume products.Fig.A shows a basic step procedure (a)that you can integrate into a routine (b);the routine executes a clockwise rotation of N steps at a fixed rate.The step rate is defined by a software loop,but you can also use programmed timer interrupts.Fig.A :A µC can generate the phase sequence (a)for a stepper motor.A routine (b)expands a single-step routine into are that executes a move of N steps.A simpler approach uses the software equivalent of a shift register.For example,you can load a 99(hex)into a register and take the phases from bits 0to 3.A Rotate Left instruction yields a clockwise step ;a Rotate Right instruction causes a counterclockwise move.When software translation ties up your µC,lighten the load by adding a hardware translator.In applications in-volving unidirectional motors,this logic circuit (fig.B)re-quires only one pulse for each step ;you’ll also need a direction signal (b)if your motor rotates in both direc-tions.By adding a 7408to a 2-phase translator,you can satisfy a wave-drive application (c),while the addition of two OR gates provides fast turn-off in wave-drive mode.Fig.B :Built a simple 2-phase hardware translatorusing a dual flip-flop,for single (a)or bidirec-tional (b)rotation.Add some extra ICs for wave-drive signals (c)and to provide fast turn-off (d).a)b)b)c)d)a)APPLICATION NOTE4/8Often aµC controls the translator,setting the direction line and providing a pulse for each step.Software is thus simplified,and if you use a programmed interrupt scheme,theµC is free to handle other tasks.Fig.C de-scribes an absolute-positioning routine for a step with a direction-control translator;Fig.D outlines how pro-grammed timer interrupts are used to relieve the bur-den on the C.Two special cases call for hardware translation.The first is in a system for which you have already designed in control circuitry to provide step and direction signals. The second case involves single-quantity and small-run applications,in which thecost of a fewICs is a small price to pay for simplified software.Figure C:For use with a Hardware Trans-lator this a Absolute-positioningRoutine Sets the Direction Lineand Sends the AppropriateNumber of Step Pulses. Figure D:To Set a motor Step Rate,usedProgrammed Timer Interruptsin Place of Software TimingLoops.Notes:Enter with de-sired position current po-sition in register or mem-APPLICATION NOTE5/8CHOPPER CIRCUIT OFFERS MORE EN-HANCEMENTSAdding a chopper circuit to maintain a constant-ave-rage phase current improves performance and effi-ciency.Fig.3showna simple constant-currentdrive that employs a dual bridge,dual comparator and a few passive components.This circuit requires an L293E,because this dual-bridge IC offers access to the lower emitter connections,thus letting you insert current-sensing resistors.Operation of this fixed-ripple chopper drive is strai-ghtforward.When theµC or translator activates a bridge,theincreasing load current raises thevoltage across the sensing resistor until it equals the com-parator’s reference voltage.The comparator then switches,clamping the translator signals through the diodes to deactivate the bridge.As the current decays,the voltage across the sensing resistor de-creases until it equals the comparator’s lower thre-shold.The comparator switches again,allowing the µC or translator to activate a bridge and restart the cycle.Aslong as the translatordrives the bridge,this sequence repeats to provide a constant-average phase current with fixed ripple.V ref adjuststhe lower current limit,while the compa-rator’s hysteresis sets the ripple,and hence the peak current.Although a divider establishes the va-lue of V ref in this case,you can employ the dual-sup-ply design approachand switch V ref toa lower value when the motor is idle.In addition,use of a D/A con-verter establishes V ref for micro-stepping applica-tions.This drive circuit,with its fixed-ripple current characteristics,is well suited for such service. FIXED-FREQUENCY CHOPPER IS MOTOR INDEPENDENTFig.3’s drive has some disadvantages.First,the chopper frequency depends on motor characteris-tics,and these parameters vary from unit to unit.In addition,it’s impossible to synchronize the chop-pers,and this shortcoming can cause trouble on the ground plane.Using a flip flop/comparator arrangement(fig.4)to develop a fixed-frequency chopper overcomes the-se problems.In this circuit,the NE555timer gene-rates negative pulses that reset the flip flops to enable the phase-controlsignalsfrom the translator. If these signals are set to energize a winding,theFigure4:This Fixed-frequency Constant-current Chopper Driver Enables the Synchronization of Several Drives,thus Minimizing Potential Ground-plane Problems.APPLICATION NOTE6/8Figure5:A Special Translator-chopper Control Circuit cuts the Drivers Components Count to the Mini-mum.current in that winding rises until the voltage across the sensing resistor switches the comparator,thus setting the flip flop.This disables the phase signals and deactivates the bridge.Current in the winding falls until the next clock pulseresets the flip flop,and the sequence repeats to maintain a constant cur-rent.CONTROLLER IC REDUCES COMPONENT COUNTIf you’re using a hardware translation and constant-current choppers,you can further reduce the com-ponent count by using a controller chip such as the L297–a20-pin DIP that houses a translator and a dual fixed-frequencychoppercircuit.Under the con-trol of step and direction inputs,the L297generates normal,wave-drive and half-step sequences.As shown in fig.5,the controller connectsdirectly to a dualbridge.Externalcomponentrequirementsare minimal:and RC network to set the chopper fre-quency and a resistive divider to establish the com-parator reference voltage(V ref).To accommodatemotorswith a phase currentasgreat as3.5A,replace the single dual-bridge ICwith two de-vices configured in parallel(input to input,enable to enable,etc)to form a single bridge.It’s extremely im-portant thatyou pair the half bridges–1with4and2 with3–to ensure optimum current sharing.Reprinted from EDN.11/24/83©1986CahnersPublishing Company Division ofReed Publishing USA.APPLICATION NOTE7/8APPLICATION NOTEInformation furnished is believed to be accurate and reliable.However,SGS-THOMSON Microelectronics assumes no responsibility for the consequences of use of such information nor for any infringement of patents or other rights of third parties which may result from its use. No license is granted by implication or otherwise under any patent or patent rights of SGS-THOMSON Microelectronics.Specifications mentioned in this publication are subject to change without notice.This publication supersedes and replaces all information previously supplied.SGS-THOMSON Microelectronics products are not authorized for use as critical components in life support devices or systems without express written approval of SGS-THOMSON Microelectronics.©1995SGS-THOMSON Microelectronics-All Rights ReservedSGS-THOMSON Microelectronics GROUP OF COMPANIESAustralia-Brazil-France-Germany-Hong Kong-Italy-Japan-Korea-Malaysia-Malta-Morocco-The Netherlands-Singapore-Spain-Sweden-Switzerland-Taiwan-Thaliand-United Kingdom-U.S.A.8/8。

L293D采用16引脚DIP封装，其内部集成了双极型H-桥电路，所有的开量都做成n型。

这种双极型脉冲调宽方式具有很多优点，如电流连续；电机可四角限运行；电机停止时有微振电流，起到“动力润滑”作用，消除正反向时的静摩擦死区：低速平稳性好等。

L293D通过内部逻辑生成使能信号。

H-桥电路的输入量可以用来设置马达转动方向，使能信号可以用于脉宽调整（PWM）。

另外，L293D 将2个H-桥电路集成到1片芯片上，这就意味着用1片芯片可以同时控制2个电机。

每1个电机需要3个控制信号EN12、IN1、IN2，其中EN12是使能信号，IN1、IN2为电机转动方向控制信号，IN1、IN2分别为1，0时，电机正转，反之，电机反转。

选用一路PWM连接EN12引脚，通过调整PWM的占空比可以调整电机的转速。

选择一路I/O口，经反向器74HC14分别接IN1和IN2引脚，控制电机的正反转L293D集成电路说明L293DPUSH-PULL FOUR CHANNEL DRIVER WITH DIODES推拉4通道驱动带二极管600mA. OUTPUT CURRENT CAPABILITY PER CHANNEL600mA输出电流每通道1.2A PEAK OUTPUT CURRENT (NON REPETITIVE) PER CHANNEL1.2A峰值输出电流每通道(不可重复，估计将会损坏)ENABLE FACILITY使用简易OVERTEMPERATURE PROTECTION温度过高保护LOGICAL ”0” INPUT VOLTAGE UP TO 1.5v(HIGH NOISE IMMUNITY逻辑"0"输入电压为1.5V,可以免除1.5V以下的干扰INTERNAL CLAMPS DIODES内置钳位二极管DESCRIPTION描述The L293D is a monolithic integrated high voltage,high current four channel vriver designed to acceptstandard DTL or TTL logic levels and drive induc-tiveloads (such as relays solenoides, DC andstepping motors) and switching power transistors.L293D 是单块集成电路，高电压，高电流，四通道驱动，设计用来接受DTL或者TTL逻辑电平，驱动感性负载(比如继电器，直流和步近马达)，和开关电源晶体管。

L293D介绍L293D是一种常见的集成电路芯片，用于驱动直流电机和步进电机。

它具有多种功能，包括电机驱动、电流放大器、逻辑电平转换等。

L293D可广泛应用于机器人、无人机、汽车等电动装置中。

在本文档中，我们将介绍L293D的主要特点和功能，并提供使用L293D驱动电机的示例电路。

特点以下是L293D的主要特点：1.可同时控制两个直流电机或一个步进电机。

2.具有过热保护功能，确保芯片在超过额定温度时能自动断电。

3.具有内部电流限制功能，可确保电机不会超过额定电流。

4.可以通过外部电源提供电源电压以驱动电机。

5.具有4个输入引脚，用于控制电机的运行方向和速度。

引脚配置L293D芯片的引脚配置如下：L293D引脚配置L293D引脚配置以下是每个引脚的功能：•1号引脚：使能1（Enable 1）- 连接到控制电机1的PWM输入引脚。

•2号引脚：输出1（Output 1）- 与电机1的正极连接。

•3号引脚：输出2（Output 2）- 与电机1的负极连接。

•4号引脚：地（Ground）- 连接到电路的地线。

•5号引脚：输入1（Input 1）- 连接到控制电机1的方向控制引脚。

•6号引脚：输入2（Input 2）- 连接到控制电机1的方向控制引脚。

•7号引脚：使能2（Enable 2）- 连接到控制电机2的PWM输入引脚。

•8号引脚：输出3（Output 3）- 与电机2的正极连接。

•9号引脚：输出4（Output 4）- 与电机2的负极连接。

•10号引脚：电源电压（VCC2）- 连接到外部电源电压引脚。

•11号引脚：地（Ground）- 连接到电路的地线。

•12号引脚：输入3（Input 3）- 连接到控制电机2的方向控制引脚。

•13号引脚：输入4（Input 4）- 连接到控制电机2的方向控制引脚。

•14号引脚：电源电压（VCC1）- 连接到外部电源电压引脚。

使用示例下面是使用L293D驱动直流电机的示例电路图：- 将电源正极连接到VCC1引脚，电源负极连接到地引脚和V CC2引脚。