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摘要 LMD18200 是美国国家半导体公司(NS)推出的专用于直流电动机驱动的 H 桥组件。同一芯片上集成有 CMOS 控制电路和 DMOS 功率器件， 利用它可以与主处理器、 电机和增量型编码器构成一个完整的运动控制系统。LMD18200 广泛应用于打印机、机器人和各种自动化控制领域。本文介绍了 LMD18200 芯片的结构、原理及其典型应用。 关键词 LMD18200 MC68332 PWM 双极性驱动 单极性驱动 1、 主要性能1、 主要性能 l 峰值输出电流高达 6A，连续输出电流达 3A； l 工作电压高达 55V； l Low RDS(ON) typically 0.3W per switch； l TTL/CMOS 兼容电平的输入； l 无 “shoot-through” 电流； l 具有温度报警和过热与短路保护功能； l 芯片结温达 145，结温达 170时，芯片关断； l 具有良好的抗干扰性。 2、 典型应用2、 典型应用 l 驱动直流电机、步机电机 l 伺服机构系统位置与转速 l 应用于机器人控制系统 l 应用于数字控制系统 l 应用于电脑打印机与绘图仪 3、 内部结构和引脚说明3、 内部结构和引脚说明 LMD18200 外形结构如图 1 所示，内部电路框图 2 如图所示。它有 11 个引脚,采用 TO-220 和双列直插式封装。 各引脚的功能如下： 引脚 名称 功能描述 1、11 桥臂 1，2 的自举输入电容连接端 在脚 1 与脚 2、脚 10 与脚 11 之间应接入 10uF 的自举电容 2、10 H 桥输出端 3 方向输入端 转向时， 输出驱动电流方向见表 1。 该脚控制输出 1 与输出 2 （脚2、10）之间电流的方向，从而控制马达旋转的方向。 4 刹车输入端 刹车时，输出驱动电流方向见表 1。通过该端将马达绕组短路而使其刹车。刹车时，将该脚置逻辑高电平，并将 PWM 信号输入端（脚 5）置逻辑高电平，3 脚的逻辑状态决定于短路马达所用的器件。3 脚为逻辑高电平时，H 桥中 2 个高端晶体管导通；3脚呈逻辑低电平时，H 桥中 2 个低端晶体管导通。脚 4 置逻辑高电平、脚 5 置逻辑低电平时，H 桥中所有晶体管关断，此时，每个输出端只有很小的偏流（1.5mA）。 5 PWM 信号输入端 PWM 信号与驱动电流方向的关系见表 1。 该端与 3 脚 （方向输入）如何使用，决定于 PWM 信号类型。 6、7 电源正端与负端 8 电流取样输出端 提供电流取样信号，典型值为 377 A/A。 9 温度报警输出 温度报警输出，提供温度报警信号。芯片结温达 145时，该端变为低电平；结温达 170时，芯片关断。 表 1 LMD18200 逻辑真值表 PWM 转向 刹车 实际输出驱动电流 电机工作状态 H H L 流出 1、流入 2 正转 H L L 流入 1、流出 2 反转 L L 流出 1、流出 2 停止 H H H 流出 1、流出 2 停止 H L H 流入 1、流入 2 停止 L X H NONE LMD18200 工作原理LMD18200 工作原理： 内部集成了四个 DMOS 管，组成一个标准的 H 型驱动桥。通过充电泵电路为上桥臂的 2 个开关管提供栅极控制电压，充电泵电路由一个 300kHz 左右的工作频率。可在引脚 1、11 外接电容形成第二个充电泵电路，外接电容越大，向开关管栅极输入的电容充电速度越快，电压上升的时间越短，工作频率可以更高。引脚 2、10 接直流电机电枢，正转时电流的方向应该从引脚步到引脚 10；反转时电流的方向应该从引脚 10 到引脚 2。电流检测输出引脚 8 可以接一个对地电阻，通过电阻来输出过流情况。内部保护电路设置的过电流阈值为 10A，当超过该值时会自动封锁输出，并周期性的自动恢复输出。如果过电流持续时间较长，过热保护将关闭整个输出。过热信号还可通过引脚 9 输出，当结温达到 145 度时引脚 9 有输出信号。 4、 典型应用4、 典型应用 LMD18200 典型应用电路如图 3 所示。 LMD18200 提供双极性驱动方式和单极性驱动方式。双极性驱动是指在一个 PWM 周期里，电动机电枢的电压极性呈正负变化。 双极性可逆系统虽然有低速运行平稳性的优点， 但也存在着电流波动大，功率损耗较大的缺点，尤其是必须增加死区来避免开关管直通的危险，限制了开关频率的提高，因此只用于中小功率直流电动机的控制。本文中将介绍单极性可逆驱动方式。单极性驱动方式是指在一个 PWM 周期内,电动机电枢只承受单极性的电压。 该应用电路是 Motorola 68332CPU 与 LMD18200 接口例子，它们组成了一个单极性驱动直流电机的闭环控制电路。在这个电路中，PWM 控制信号是通过引脚 5 输入的，而转向信号则通过引脚 3输入。 根据 PWM 控制信号的占空比来决定直流电机的转速和转向。 采用一个增量型光电编码器来反馈电动机的实际位置，输出 AB 两相，检测电机转速和位置，形成闭环位置反馈，从而达到精确控制电机。 5、 结束语5、 结束语 电动机的数字控制是电动机控制的发展趋势， 用单片机对电动机进行控制是实现电动机数字控制的最常用的手段。使用专门的电机控制芯片 LMD18200 可以减轻单片机负担，工作更可靠。 LMD182003A, 55V H-BridgeGeneral DescriptionThe LMD18200 is a 3A H-Bridge designed for motion controlapplications. The device is built using a multi-technology pro-cess which combines bipolar and CMOS control circuitrywith DMOS power devices on the same monolithic structure.Ideal for driving DC and stepper motors; the LMD18200 ac-commodates peak output currents up to 6A. An innovativecircuit which facilitates low-loss sensing of the output currenthas been implemented.Featuresn Delivers up to 3A continuous outputn Operates at supply voltages up to 55Vn Low RDS(ON) typically 0.3 per switchn TTL and CMOS compatible inputsn No “shoot-through” currentn Thermal warning flag output at 145Cn Thermal shutdown (outputs off) at 170Cn Internal clamp diodesn Shorted load protectionn Internal charge pump with external bootstrap capabilityApplicationsn DC and stepper motor drivesn Position and velocity servomechanismsn Factory automation robotsn Numerically controlled machineryn Computer printers and plottersFunctional DiagramDS010568-1FIGURE 1. Functional Block Diagram of LMD18200December 1999LMD18200 3A, 55V H-Bridge 1999 National Semiconductor CorporationDS010568Connection Diagrams and Ordering InformationDS010568-211-Lead TO-220 PackageTop ViewOrder Number LMD18200TSee NS Package TA11BDS010568-2524-Lead Dual-in-Line PackageTop ViewOrder Number LMD18200-2D-QV5962-9232501VXALMD18200-2D/8835962-9232501MXASee NS Package DA24BLMD182002Absolute Maximum Ratings(Note 1)If Military/Aerospace specified devices are required,please contact the National Semiconductor Sales Office/Distributors for availability and specifications.Total Supply Voltage (VS, Pin 6)60VVoltage at Pins 3, 4, 5, 8 and 912VVoltage at Bootstrap Pins(Pins 1 and 11)VOUT+16VPeak Output Current (200 ms)6AContinuous Output Current (Note 2)3APower Dissipation (Note 3)25WPower Dissipation (TA= 25C, Free Air)3WJunction Temperature, TJ(max)150CESD Susceptibility (Note 4)1500VStorage Temperature, TSTG40C to +150CLead Temperature (Soldering, 10 sec.)300COperating Ratings(Note 1)Junction Temperature, TJ40C to +125CVSSupply Voltage+12V to +55VElectrical Characteristics(Note 5)The following specifications apply for VS= 42V, unless otherwise specified. Boldface limits apply over the entire operatingtemperature range, 40C TJ +125C, all other limits are for TA= TJ= 25C.SymbolParameterConditionsTypLimitUnitsRDS(ON)Switch ON ResistanceOutput Current = 3A (Note 6)0.330.4/0.6 (max)RDS(ON)Switch ON ResistanceOutput Current = 6A (Note 6)0.330.4/0.6 (max)VCLAMPClamp Diode Forward DropClamp Current = 3A (Note 6)1.21.5V (max)VILLogic Low Input VoltagePins 3, 4, 50.1V (min)0.8V (max)IILLogic Low Input CurrentVIN= 0.1V, Pins = 3, 4, 510A (max)VIHLogic High Input VoltagePins 3, 4, 52V (min)12V (max)IIHLogic High Input CurrentVIN= 12V, Pins = 3, 4, 510A (max)Current Sense OutputIOUT= 1A (Note 8)377325/300A (min)425/450A (max)Current Sense Linearity1A IOUT 3A (Note 7)69%Undervoltage LockoutOutputs turn OFF9V (min)11V (max)TJWWarning Flag TemperaturePin 9 0.8V, IL= 2 mA145CVF(ON)Flag Output Saturation VoltageTJ= TJW, IL= 2 mA0.15VIF(OFF)Flag Output LeakageVF= 12V0.210A (max)TJSDShutdown TemperatureOutputs Turn OFF170CISQuiescent Supply CurrentAll Logic Inputs Low1325mA (max)tDonOutput Turn-On Delay TimeSourcing Outputs, IOUT= 3A300nsSinking Outputs, IOUT= 3A300nstonOutput Turn-On Switching TimeBootstrap Capacitor = 10 nFSourcing Outputs, IOUT= 3A100nsSinking Outputs, IOUT= 3A80nstDoffOutput Turn-Off Delay TimesSourcing Outputs, IOUT= 3A200nsSinking Outputs, IOUT= 3A200nstoffOutput Turn-Off Switching TimesBootstrap Capacitor=10 nFSourcing Outputs, IOUT= 3A75nsSinking Outputs, IOUT= 3A70nstpwMinimum Input Pulse WidthPins 3, 4 and 51stcprCharge Pump Rise TimeNo Bootstrap Capacitor20sLMD182003Electrical Characteristics NotesNote 1: Absolute Maximum Ratings indicate limits beyond which damage to the device may occur. DC and AC electrical specifications do not apply when op-erating the device beyond its rated operating conditions.Note 2: See Application Information for details regarding current limiting.Note 3: The maximum power dissipation must be derated at elevated temperatures and is a function of TJ(max), JA, and TA. The maximum allowable power dis-sipation at any temperature is PD(max)=(TJ(max) TA)/JA, or the number given in theAbsolute Ratings, whichever is lower. The typical thermal resistance from junc-tion to case (JC) is 1.0C/W and from junction to ambient (JA) is 30C/W. For guaranteed operation TJ(max)=125C.Note 4: Human-body model, 100 pF discharged through a 1.5 k resistor. Except Bootstrap pins (pins 1 and 11) which are protected to 1000V of ESD.Note 5: All limits are 100% production tested at 25C. Temperature extreme limits are guaranteed via correlation using accepted SQC (Statistical Quality Control)methods. All limits are used to calculate AOQL, (Average Outgoing Quality Level).Note 6: Output currents are pulsed (tW2 ms, Duty Cycle30V) so someprecautions are in order. Proper heat sink design is essentialand it is normally necessary to heat sink the VCCsupply pin(pin 6) with 1 square inch of copper on the PCB.DS010568-24FIGURE 4. Transitions in Brake, Direction, or PWM Must Be Separated By At Least 1 secLMD182007Application Information(Continued)INTERNAL CHARGE PUMP AND USE OF BOOTSTRAPCAPACITORSTo turn on the high-side (sourcing) DMOS power devices,the gate of each device must be driven approximately 8Vmore positive than the supply voltage. To achieve this an in-ternal charge pump is used to provide the gate drive voltage.As shown inFigure 5, an internal capacitor is alternatelyswitched to ground and charged to about 14V, then switchedto V supply thereby providing a gate drive voltage greaterthan V supply. This switching action is controlled by a con-tinuously running internal 300 kHz oscillator. The rise time ofthis drive voltage is typically 20 s which is suitable for oper-ating frequencies up to 1 kHz.For higher switching frequencies, the LMD18200 providesfor the use of external bootstrap capacitors. The bootstrapprinciple is in essence a second charge pump whereby alarge value capacitor is used which has enough energy toquickly charge the parasitic gate input capacitance of thepower device resulting in much faster rise times. The switch-ing action is accomplished by the power switches them-selvesFigure 6. External 10 nF capacitors, connected fromthe outputs to the bootstrap pins of each high-side switchprovide typically less than 100 ns rise times allowing switch-ing frequencies up to 500 kHz.INTERNAL PROTECTION DIODESA major consideration when switching current through induc-tive loads is protection of the switching power devices fromthe large voltage transients that occur. Each of the fourswitches in the LMD18200 have a built-in protection diode toclamp transient voltages exceeding the positive supply orground to a safe diode voltage drop across the switch.The reverse recovery characteristics of these diodes, oncethe transient has subsided, is important. These diodes mustcome out of conduction quickly and the power switches mustbe able to conduct the additional reverse recovery current ofthe diodes. The reverse recovery time of the diodes protect-ing the sourcing power devices is typically only 70 ns with areverse recovery current of 1A when tested with a full 6A offorward current through the diode. For the sinking devicesthe recovery time is typically 100 ns with 4A of reverse cur-rent under the same conditions.Typical ApplicationsFIXED OFF-TIME CONTROLThis circuit controls the current through the motor by apply-ing an average voltage equal to zero to the motor terminalsfor a fixed period of time, whenever the current through themotor exceeds the commanded current. This action causesthe motor current to vary slightly about an externally con-trolled average level. The duration of the Off-period is ad-justed by the resistor and capacitor combination of theLM555. In this circuit the Sign/Magnitude mode of operationis implemented (see Types of PWM Signals).DS010568-6FIGURE 5. Internal Charge Pump CircuitryDS010568-7FIGURE 6. Bootstrap CircuitryLMD182008Typical Applications(Continued)TORQUE REGULATIONLocked Anti-Phase Control of a brushed DC motor. Current sense output of the LMD18200 provides load sensing. The LM3525Ais a general purpose PWM controller. The relationship of peak motor current to adjustment voltage is shown inFigure 10.DS010568-10FIGURE 7. Fixed Off-Time ControlDS010568-11FIGURE 8. Switching WaveformsLMD182009Typical Applications(Continued)VELOCITY REGULATIONUtilizes tachometer output from the motor to sense motor speed for a locked anti-phase control loop. The relationship of motorspeed to the speed adjustment control voltage is shown inFigure 12.DS010568-12FIGURE 9. Locked Anti-Phase Control Regulates TorqueDS010568-13FIGURE 10. Peak Motor Currentvs Adjustment VoltageLMD1820010Typical Applications(Continued)DS010568-14FIGURE 11. Regulate Velocity with Tachometer FeedbackDS010568-15FIGURE 12. Motor Speed vsControl VoltageLMD1820011Physical Dimensionsinches (millimeters) unless otherwise noted11-Lead TO-220 Power Package (T)Order Number LMD18200TNS Package Number TA11BLMD1820012Physical Dimensionsinches (millimeters) unless otherwise noted (Continued)LIFE SUPPORT POLICYNATIONALS PRODUCTS ARE NOT AUTHORIZED FOR USE AS CRITICAL COMPONENTS IN LIFE SUPPORTDEVICES OR SYSTEMS WITHOUT THE EXPRESS WRITTEN APPROVAL OF THE PRESIDENT AND GENERALCOUNSEL OF NATIONAL SEMICONDUCTOR CORPORATION. As used herein:1. Life support devices or systems are devices orsystems which, (a) are intended for surgical implantinto the body, or (b) support or sustain life, andwhose failure to perform when properly used inaccordance with instructions for use provided in thelabeling, can be reasonably expected to result in asignificant injury to the user.2. A critical component is any component of a lifesupport device or system whose failure to performcan be reasonably expected to cause the failure ofthe life support device or system, or to affect itssafety or effectiveness.National SemiconductorCorporationAmericasTel: 1-800-272-9959Fax: 1-800-737-7018Email: supportNational SemiconductorEuropeFax: +49 (0) 1 80-530 85 86Email: europe.supportDeutsch Tel: +49 (0) 1 80-530 85 85EnglishTel: +49 (0) 1 80-532 78 32Franais Tel: +49 (0) 1 80-532 93 58ItalianoTel: +49 (0) 1 80-534 16 80National SemiconductorAsia Pacific CustomerResponse GroupTel: 65-2544466Fax: 65-2504466Email: sea.supportNational SemiconductorJapan Ltd.Tel: 81-3-5639-7560Fax: 81-3-5639-750724-Lead Dual-in-Line PackageOrder Number LMD18200-2D-QV5962-9232501VXALMD18200-2D/8835962-9232501MXANS Package Number DA