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Motor Control


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116 Control and Automation Solutions Guide


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117Motor Control

IntroductionMotor control design for industrialapplications requires attentionto both superior performance

and ruggedness. Maxims featureintegration and superior specicationsenhance motor controller equipmentprecision while improving robustnessin harsh industrial environments.

Motor controllers either control variablepower supplies to the motor or toelectronic switches between the powersupply and the motor. These switchesare precisely timed to open and close tomake the motor rotate most effectively. The timing is often governed by complexmathematical equations based on motorarchitecture and electromagnetic theory.Depending on the application, a motorcontroller can be as simple as a variable-voltage generator, a pulsed-DC voltagesource, or a complex signal generatorrequiring sophisticated digital signalprocessing algorithms to generate thecorrect timing. For large motors, those inthe multihorsepower range with multiplepower phases, precise control is essential.At a minimum, the wrong timing canresult in extreme power use. In the

worst case, wrong timing can destroythe motor and the installation itself.

Many electric motors have maximumtorque at zero RPM, so these largemotors must be soft-started. To reducemaintenance to a minimum, themechanical mechanisms (clutches)that traditionally provided this soft-start capability are rapidly beingreplaced by electronic soft-starters orvariable frequency drives (VFDs). Insome applications motors must supplyboth forward and reverse tension tothe load; optimally, braking energyfrom overhauling loads is fed backinto the AC line using regenerativeVFDs instead of being wasted as heatin large braking resistors or in high-maintenance mechanical brakes.

Motor control is a very signicant portionof the Control and Automation market.According to U.S. Department of Energy,motor driven equipment accounts for64% of the electricity consumed by U.S.

industries. Furthermore, electric motorsconsume about 45% of the worldselectricity according to the International

Energy Agency (IEA) report of May2011 on global energy consumptionby electric motor driven systems. Bycomparison, lighting is a distant secondconsuming 19%. With the cost of energyrising steadily, plant operators look forways to reduce energy consumptionwhile maintaining throughput.Furthermore, with the availability ofreasonably priced and highly capablemotor controllers for all types of motors,plant engineers are free to choose motortypes that are less expensive, more

efficient, and require less maintenance. To put the energy savings opportunityin perspective, compare motor powerconsumption vs. speed when drivingfans and centrifugal pumps. The torqueneeded rises with speed, resulting inpower draw that is proportional tothe cube of the speed! In other words,reducing the speed to one-half of fullspeed drops the power to one-eighthof full power. Even dropping the speedto 75% of full speed drops the power

consumption to 42% of full power (0.75cubed = 0.42). It is clear that signicantsavings in energy use can be realizedby even small reductions in speed. Thisfact, in turn, justies the use of VFDs inapplications that can tolerate the speedreduction. Of course, speed reductionequates to performing the work moreslowly, which, in some cases, directlyimpacts throughput. Nonetheless,there are numerous applications wheremotors do not need to run at full speedto accomplish the work quickly enough.

Pumping out a tank of uid may notneed to be done as fast as possible.Venting a room may need a full-speedfan at rst, but once the air is moving aslower speed may suffice. The EIA report(May 2011) states that it is feasible andcost effective to save 20% to 30% of totalmotor power consumption worldwide.

Certainly adding variable-speedcontrollers adds cost to the installation;however, the forecasted energy

savings will soon offset those initialexpenses. The return-on-investmentcalculations are often straightforward.

Interfacing to the MotorControllerA very important aspect of everymotor controller in the industrialcontrol and automation setting is thecommunications interface betweenthe factory control system and theindividual motor controller. All theblock diagrams in the individual motorcontroller sections show a control panelthat provides a direct user interfaceat the controller and a standard

separately wired communicationsinterface that connects to the eldbus. The eldbus ultimately runs back to aPLC (programmable logic controller)that sends commands to the motorcontroller such as motor start, motoracceleration, speed adjustment, motorstop, etc. An additional option exists:powerline communications (PLC, not tobe confused with programmable logiccontroller). This technology gives theoption of sharing command and controlconnections with power connectionsbetween the PLC (programmable logiccontroller) and the motor controller.

Motor TypesBrushed DC Motors (BDCs)Brushed DC (BDC) motors are amongthe rst motor types put to practicaluse and they are still popular where lowinitial cost is required. These motorshave a wound rotor armature and eithera permanent magnet stator or eldwound stator. Brushes slide across thesegments of the commutator on the

rotor to switch the DC power source tothe appropriate windings on the rotor.

BDC motors have their place for twoimportant reasons: low initial cost andruggedness, because no electronics areneeded inside the motor. Because themotors suffer from wear of the brushes,brush springs, and commutators, theyrequire high maintenance in intensive-use applications. Sparking also occursbetween the brushes and the commutator

Overview


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Figure 1. Two control techniques for BDC motors. The upper diagram shows a variable voltage technique that is high efficiency due to the switching power su shows the PWM technique that can be lower cost if the motor is rated for the full supply voltage.

SWITCHDEBOUNCER

P

START

CONTROL PANEL

VARIABLE VOLTAGE TECHNIQUE

STOP

FASTER

SLOWER

DISPLAYDRIVER

DISPLAY SUPERVISOR

VCC

VCC

IOUT

VCC

BUCK

VDC

VDC

DAC

ADC

CURRENT-SENSE AMP

OP AMP

MOTORSPEED,

POSITIONSENSOR

TEMPERATURESENSOR

UART

SENSORINTERFACE

BUCK

SHDN FB

ISOLATION TRANSCEIVER

FIELDBUS

MOTOR

SWITCHDEBOUNCER

START

CONTROL PANEL

PWM TECHNIQUE

STOP

FASTER

SLOWER

DISPLAYDRIVER

DISPLAY SUPERVISOR

VCC

VDCVCC

VCC

BUCK

VDC

MOTOR SPEED,POSITION

SENSOR

TEMPERATURESENSOR

GATEDRIVER

SENSOR

INTERFACE

UART ISOLATION TRANSCEIVER

FIELDBUS

MOTOR

ADC

P

MOTOR

as a part of normal motor operation. This, in turn, creates EMI/RFI and smallamounts of ozone. Where system costis a priority, BDC motors are a low-cost solution. While their efficiency

is generally lower than brushlessDC (BLDC) motors, they approachequality under high-load conditions.

Controllers for BDC Motors The only variable available to controlthe speed of a BDC motor is the supplyvoltage. The voltage can be variedor a xed voltage can be pulsed withvariable duty cycle. For high efficiencyin a variable voltage approach, a switch-mode power supply is required. Most

designers are abandoning linear voltageregulation because of its inherentlylow efficiency. One way to realize avariable-voltage power supply fromany switch-mode voltage regulator is to

inject or extract current into or out ofits feedback node using a current sink/source DAC. See Figure 1 . When the


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Controllers for BLDC MotorsSince the commutation in a BLDC motor(Figure 4 ) is electronic, some means isrequired for detecting rotor positionrelative to the stationary armature. Typical solutions for this are Hall-effectsensors and rotary encoders such asoptical encoders, resolvers, or rotaryvariable differential transformers (RVDTs).More designs are using sensorlessapproaches where stator coil back EMFvariation is sensed, which indicatesrotor position. This information istypically sent to a microprocessor todetermine power FET drive timing.Various user interfaces allow soft-starting, acceleration control, speedcontrol, and response to locked rotor.

Stepper MotorsStepper motors are really more likerotary positioners than motors. They areusually smaller motors with many polesused for precise positioning applications(Figure 5 ). They are often driven openloop, meaning there is no positiondetection. Their position is assumed tofollow the step commands exactly. Lossof step position can occur, however, sosome mechanism must be provided toindicate slippage and to reset properpositioning. At low drive rates, theycome to a complete stop between eachstep. Many drive waveforms are possible,the simplest has each winding energizedone at a time. Other variations arepossible where overlap in energization

occurs between adjacent windings toprovide smaller steps. Microstepping isachieved with sinusoidal, overlappingcurrent waveforms that give verysmooth and quiet rotation.

DISPLAYDRIVER

UART

SUPERVISOR

SWITCHDEBOUNCER

KEYBOARDSCANNER

KEYBOARD

SWITCHES

DISPLAY

FRONT PANELHALF-BRIDGE

DRIVER

ADCs

HALF-BRIDGEDRIVER

HALF-BRIDGEDRIVER

ISOLATIONTRANSCEIVER

FIELDBUS

VCC

RESET

P

I/0

I/0

VCC

OP AMP

CURRENT-SENSEAMP x3 TEMPERATUR

SENSOR

BRUSHLESS DC MOTOR

MOTORSPEED,POSITIONSENSOR

VCC

BUCK

VDCMOSFET H-BRIDGE

SENSORINTERFACE

Figure 4. Controller for BLDC motor.

Figure 5. Stepper motor (windings removed) showintoothed rotor and stator design for fine stepping.


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121Motor Control

Controllers for Stepper MotorsStepper motors are constant powermotors if driven with a constant supplyvoltage. As speed increases, torquedecreases. This happens because ofthe limitation on current ramp rates inthe windings due to their inductance.Maximum torque is realized at zerospeed. So to increase torque at higherspeeds, high-voltage drivers withcurrent limiting are sometimes used(Figure 6 ). These are called chopperdrives, and are designed to generatea nearly constant current in eachwinding rather than simply switching aconstant voltage. On each step, a veryhigh voltage is applied to the winding.When the current limit is reached, thevoltage is turned off or chopped. Atthis point the winding current startsramping down to a lower limit wherethe voltage is again turned on, keepingthe winding current relatively constant

for a particular step position. Theadditional electronics to sense windingcurrents and to control the switchingadds some cost and complexity, butit allows stepper motors to be driven

with high torque at high speed.Microprocessors are commonlyincorporated in stepper motor driversto provide the controls needed.Sophisticated control capability iscommon for stepper motors since theyare often employed in machines thatrequire fast precision movements, suchas in robotics. Acceleration/decelerationproles, holding torque, and otherparameters are often provided for.

Switched Reluctance Motors (SRMs)Switched reluctance motors (SRMs)are a form of stepper motor, but areusually much larger and have fewerpoles than the traditional steppermotor. The key to these motors is that

the rotor is made of only ferromagneticmaterial and has no windings. It is avery reliable, low-maintenance motorwith high power density at low cost,all of which come at the expense of

more complex electronic controls.Opposing stator poles are energized insequence and the rotor poles closestto the energized stator poles becomemagnetized and are attracted to them,reducing magnetic reluctance whenbrought into alignment. Before fullalignment is achieved, the next phaseis energized to keep the motor turning. There is no need for any transfer ofelectrical power to the rotor so there areno brushes, commutators, or slip rings.

With electrical commutation there areno sparks so these motors can be usedin explosive environments. They are alsogood for holding a load in a stationaryposition for long periods of time.

DISPLAYDRIVER

SWITCH

DEBOUNCER

KEYBOARDSCANNER

KEYBOARD

SWITCHES

DISPLAY

FRONT PANEL

P

VCC

VCC

BUCK

VDC

OP AMP

UART ISOLATION TRANSCEIVER

FIELDBUS

ADC

GATEDRIVER

GATEDRIVER

STEPPERMOTOR

SUPERVISOR

VCC

VDC

SHDN

BOOST

VDC

TEMPERATURESENSOR

Figure 6. Controller for stepper motor. The boost regulator and the current sense per phase allow current to ramp quickly in each pole of the motor. Motor response i phase is reached, the boost regulator is shut down until the minimum current per phase is reached again. The cycle is repeated until the next step is made.


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Controllers for SRMsSRMs are similar to stepper motorsbecause they need power switched to theproper windings at the appropriate times. The most common conguration is similarto an H-bridge, but differs somewhat. Thedriver is called an N+1 switch and diodeasymmetric bridge converter ( Figure 7 ). It

allows each phase of a 3-phase motorto be energized by the top FET and theappropriate bottom FET, which are bothturned on simultaneously ( Figure 8 ). Thecurrent is allowed to ramp up to a limit,

at which point the top FET is turned off. This is the freewheeling mode, where thewinding inductance keeps the current

relatively constant, ramping down onlyvery slowly with the bottom diodeclosing the loop around the winding. Then to discharge the phase quickly inpreparation for the next step, the bottom

FET is also turned off. The voltage acrossthe winding is now clamped to theopposite polarity by the top and bottomdiodes. This causes the current to rampdown at about the same rate that itramped up, except for the effect of twoadditional diode drops making it rampdown slightly faster. This congurationallows each phase to be switched onand off quickly, especially with a high-voltage supply, allowing for high-speedmotor operation at high torque. Figure 8shows only a single current-sense ampsensing the current on the high-side FET. This is only adequate for simple controlsystems. Complete control also requirescurrent sensing on each low-side FET.

DISPLAYDRIVER

SWITCHDEBOUNCER

KEYBOARDSCANNER

KEYBOARD

SWITCHES

DISPLAY

FRONT PANEL

LOW-SIDE

GATE DRIVERS

HIGH-SIDEGATE DRIVER

325V DC OR 650V DC


DC-DCCONVERTER

FIELDBUS

RESET

P

I/0

CURRENT-SENSE AMPI/0

TEMPERATURESENSOR

SWITCHEDRELUCTANCEMOTOR

VR ORHALL-EFFECT

SENSOR

SENSORINTERFACE

VOLTAGESUPERVISOR

AC-DCCONVERTER

AC MAINS (3-PHASE)230V AC OR 460V AC

UART

ADC

Figure 8. Controller for a switched reluctance motor.

1 2 3

V

0

1

1

2

2 3

3

Figure 7. N+1 switch and diode asymmetric bridge for driving SRMs. The control circuitry needed for the IGBTs shown is shown in Figure 8.


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123Motor Control

AC Induction Motor The AC induction motor ( Figure 9 )is the workhorse motor for manyindustrial applications such as thosefor driving pumps, blowers, conveyors,cranes, etc. It is one of the simplest andmost reliable motor designs and canrange in size from a few watts to manykilowatts. The induction motor is anasynchronous motor and is basically anAC transformer with a rotating shortedsecondary. The primary winding (stator)is connected to the power source and

the secondary winding (rotor) carriesthe induced secondary current creatinga magnetic eld. Torque is produced asthe rotor eld tries to align itself withthe applied rotating stator eld. No

slip rings or commutators are neededsince no source power is physicallyconnected to the rotor. The mostcommon designs have three statorwindings and are driven from 3-phaseAC sources. Although direct connectionto AC mains is therefore possible, inmost applications, induction motorsrequire some form of soft-starter or VFD.

Induction motors slip under load. Theamount of slip is directly proportionalto the torque required to drive the load.

Under no-load conditions, no torqueis produced and the rotational speedis almost exactly the driving frequencydivided by the number of poles in thestator. These motors are easily speed andtorque controlled by varying the drive

frequency and voltage, respectively.If constant speed is needed, VFDscan use position- or speed-detectionfeedback to increase the drive frequencyas needed to keep the motor speed

constant under varying loads.Controllers for AC Induction MotorsAC induction motors operate withthe least torque ripple when thephase current is sinusoidal. Due to theinductance of the windings, the phasecan be PWM driven from a xed DCsupply to achieve this current waveform. The two most common approaches toinduction motor drive include vectorcontrol and direct torque control. These techniques are beyond the scope

of this document, but informationis readily available. Suffice it to saythat to fully implement these controltechniques, a fairly powerful processoror DSP is required, but the benets aremany. The result is a VFD ( Figure 10 )

DISPLAYDRIVER

SWITCHDEBOUNCER

KEYBOARDSCANNER

KEYBOARD

SWITCHES

DISPLAY

FRONT PANEL

LOW-SIDEGATE DRIVERS

HIGH-SIDEGATE DRIVERS

ANALOG VOLTAGE/ CURRENT SENSORS

IGBT H-BRIDGE325V DC OR 650V DC


DC-DCCONVERTER

FIELDBUSRESET

P

I/0

CURRENT-SENSE AMPSI/0

TEMPERATURSENSOR

AC INDUCTION MOTOR

VR ORHALL-EFFECTSENSOR

SENSORINTERFACE

VOLTAGESUPERVISOR

AC-DCCONVERTER

AC MAINS (3-PHASE)230V AC OR 460V AC

VOLTAGE-SENSE AMPS

UART

ADC

ADC

ADC

ADC

ADC

ADC

Figure 10. Variable frequency drive for an AC induction motor.

Figure 9. An AC induction motor.


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that provides complete controlcapability over motor soft-starting,acceleration, torque, speed maintenance,deceleration, and holding torque.

Synchronous MotorsA synchronous motor runssynchronously with the AC excitationit receives. Various congurations arepossible. One approach applies theAC line to the stator windings aroundthe frame while a DC excitation isapplied through slip rings to therotor. In many synchronous motorsthe rotor has permanent magnetsinstead of DC-excited windings. High-speed synchronous motors are used inmachining applications where the cutter

speed must be maintained at preciselyxed rates or the machined-surfacenish will show signs of speed variation.

When driven mechanically,synchronous motors will produceelectricity, becoming alternators. They are used extensively in powerplants to generate grid power.

DC-excited synchronous motors canalso be used in power plants and largefactories to correct the power factor bybeing run under no load in parallel withthe large loads. As the DC excitationof the rotor is modied, it produceseither a leading or lagging power factorto cancel the nonunity power factorof the load. In this application theyare called synchronous condensers.

Controllers for AC Synchronous MotorsVarious control methods exist for ACsynchronous motors. The motorsstator windings can be driven withvariable-frequency AC signals from aVFD, thereby providing soft-startingand exacting speed control. If a lowfrequency is not rst applied to astopped synchronous motor, it will notself-start. It must be given a chanceto pull in to synchronization. Somesynchronous motors allow the rotorwindings to be shorted, temporarilyconverting it to an induction motorwhile it starts. Then once it is closeto synchronous speed, the short isopened and it becomes synchronous.

If the rotor uses DC excitation, its voltagecan vary with a high-efficiency switchingpower supply and voltage control.

Linear MotorsLinear motors are effectively motors thathave been unrolled and laid out at. The moving part is usually called theforcer and is connected to the externalpower source while the rails are linedwith permanent magnets. The oppositeconguration is also used. Everythingfrom maglev trains ( Figure 11 ) to railguns are based on this principle. Veryprecise machine positioning systemsuse these motors for cutting largeobjects with high accuracy. Linearmotors include linear induction motors

(LIMs) and linear synchronous motors(LSMs). Controllers for linear motorsare quite varied due to the wide rangeof applications for them. Nonetheless,they share similarities with VFDs.

Figure 11. Maglev train driven by a linear motor.


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125Motor Control: Featured Products

Benefits Simplicity of DC motor speed control

via digital interface Easy design reuse due to highly

scalable outputs Dual outputs with individual range

settings provide course and finemotor speed control

Sink/Source Current DAC Adjusts Power-Supply Output Voltage to Vary Supply toMotorsDS4432 The DS4432 contains two I 2C programmable current DACs that are each capable ofsinking and sourcing current up to 200A. Each DAC output has 127 sink and 127source settings that are programmable using the I 2C interface. The current DACoutputs power up in a high-impedance state. Full-scale range for each DAC is setby external resistors providing highly scalable outputs. Fine and course granularitycan be achieved by combining the two outputs when set for different ranges.

DC-DCCONVERTER

FB

OUT

SDA

SCL

OUT0

OUT0GND

RFS0

4.7k4.7k VCC

VCC

SUPPLY TO MOTOR

FS0

RFS1

FS0

R0B

R0A

DS4432

Featured Products

Typical operating circuit of the DS4432.
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Benefits Provide reliable operation in harsh

motor control environments 400V (max) input offset voltage

(VOS) -20V to +75V common-modevoltage range provides reliability formeasuring the current of inductiveloads

-40C to +125C automotivetemperature range

Integrated functionality reducessystem cost and shortens design cycle Uni/bidirectional current sensing Single-supply operation (4.5V to

5.5V) eliminates the need for asecond supply

400V (max) input offset voltage(VOS)

0.6% (max) gain accuracy error

Precise Current Measurements Ensure BetterMotor ControlMAX9918/MAX9919/MAX9920

The MAX9918/MAX9919/MAX9920 are current-sense ampliers with a -20V to +75Vinput range. The devices provide unidirectional/bidirectional current sensing in veryharsh environments where the input common-mode range can become negative.Uni/bidirectional current sensing measures charge and discharge current in a system. The single-supply operation shortens the design time and reduces the costof the overall system.

M

2B

1B

ADC

REF

A

INPUT-STAGELEVEL SHIFTER

RSENSE

VBATT

ADJUSTABLE GAIN

VCC VCC

RS+

RS-

FB

OUT

REFIN

R2

R1

GND

GNDSHDN2B

1A

C

MAX9918 MAX9920

The MAX9918/MAX9920current-sense amplifiers provide precise uni/bidirectional current sensing in very harsh environments.
http://www.maxim-ic.com/MAX9918http://www.maxim-ic.com/MAX9918http://www.maxim-ic.com/MAX9918http://www.maxim-ic.com/MAX9918http://www.maxim-ic.com/MAX9918http://www.maxim-ic.com/MAX9918


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Benefits Integrated functionality eases motor

control design, reduces system cost Select the analog or digital output

to monitor the Hall-effect sensorscondition High-side current-sense architecture

eliminates the need for a ground-return wire and saves 50% of thewiring cost

Reliable operation in a harshenvironment Protects against up to 60V supply

voltage transients Detects a short-to-ground fault

condition to protect the system

Highly Accurate, Reliable Monitoring of MotorSpeed and Position with a Sensor InterfaceMAX9621

The MAX9621 is a dual, 2-wire Hall-effect sensor interface with analog and digitaloutputs. This device enables a microprocessor to monitor the status of two Hall-effect sensors, either through the analog output by mirroring the sensor current forlinear information, or through the ltered digital output. The input current thresholdcan be adjusted to the magnetic eld. The MAX9621 provides a supply currentto two 2-wire Hall-effect sensors and operates in the 5.5V to 18V voltage range. The high-side current-sense architecture eliminates the need for a ground-returnwire without introducing ground shift. This feature saves 50% of the wiring cost.

REMOTEGROUND GND

REMOTEGROUND

NS

NS

0.1 F

BATRSET

BATTERY: 5.5V TO 18VOPERATING,

60V WITHSTANDRPU

10kRPU10k

5k

5k

1.8V TO 5.5V

MICROPROCESSOR

ADC

ADC

SLEEP

AOUT1

AOUT2

DOUT2

DOUT1

FILTER

SLEEP-MODECONTROL

REFERENCEISET REF

REF

BAT

BAT

FILTERREF

0.01 F

IN2

IN1

INPUTSHORT

DETECTION

0.01 F

100k

E C U C O N N E C T O R

MAX9621

Functional diagram of the MAX9621 Hall-effect sensor interface.
http://www.maxim-ic.com/MAX9621http://www.maxim-ic.com/MAX9621http://www.maxim-ic.com/MAX9621http://www.maxim-ic.com/MAX9621http://www.maxim-ic.com/MAX9621http://www.maxim-ic.com/MAX9621http://www.maxim-ic.com/MAX9621http://www.maxim-ic.com/MAX9621


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Benefits High integration provides accurate

phase information for precise sensingof rotor position

Differential input stage providesenhanced noise immunity Precision amplifier and comparator

allow small-signal detection Zero-crossing detection provides

accurate phase information

Improve Performance and Reliability inMotor Applications with a Differential VRSensor InterfaceMAX9924MAX9927 The MAX9924MAX9927 VR, or magnetic coil, sensor interface devices are idealfor sensing the position and speed of motor shafts, camshafts, transmissionshafts, and other rotating wheel shafts. These devices integrate a precisionamplier and comparator with selectable adaptive peak threshold and zero-crossing circuit blocks that generate robust output pulses, even in the presenceof substantial system noise or extremely weak VR signals. The MAX9924MAX9927 interface to both single-ended and differential-ended VR sensors.

Simplified block diagram of the MAX9924 VR sensor interface to a motor.

C

DIFFERENTIALAMPLIFIER

ADAPTIVE/MINIMUMAND

ZERO-CROSSINGTHRESHOLDS

INTERNAL/EXTERNALBIAS VOLTAGE

VR SENSOR

MOTOR BLOCK

MAX9924
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Benefits Industry-leading dynamic range

allows early detection of error signals 93dB SNR and -105dB THD

Simultaneous sampling eliminatesphase-adjust firmware requirements 8-, 6-, or 4-channel ADC options Lower system cost by as much as

15% over competing simultaneous-sampling ADCs

High-impedance input saves costlyprecision op amp

Bipolar input eliminates level shifter Single 5V voltage supply 20mA surge protection

Eliminate external protection

components, saving space and cost Integrated analog-input clamps and

small 8mm x 8mm TQFN packageprovide the highest density perchannel

Resolve Very Fine Motor Adjustments andOperate Higher Accuracy Systems withSimultaneous-Sampling ADCsMAX11044/MAX11045/MAX11046MAX11047/MAX11048/MAX11049

The MAX11044MAX11049 ADCs are an ideal t for motor control applicationsthat require a wide dynamic range. With a 93dB signal-to-noise ratio (SNR), theseADCs detect very ne changes to motor currents and voltages, which enables amore precise reading of motor performance over time. The MAX11044/MAX11045/MAX11046 simultaneously sample four, six, or eight analog inputs, respectively. AllADCs operate from a single 5V supply. The MAX11044MAX11046 ADCs measure5V analog inputs, and the MAX11047MAX11049 measure 0 to 5V. These ADCs alsoinclude analog input clamps that eliminate an external buffer on each channel.

The MAX11046 ADC simultaneously samples up to 8 analog-input channels.

16-BITADC

16-BITADC

16-BITADC

16-BIT

ADC

16-BITADC

POSITION

ENCODER

DSP-BASED DIGITALPROCESSING ENGINE

IGBT CURRENT DRIVERS

IPHASE1

THREE-PHASE ELECTRIC MOTOR

IPHASE3

IPHASE2

MAX11046
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Recommended Solutions

Part Description Features Benefits

AC-DC and DC-DC Converters and Controllers

MAX17499/500 Isolated/nonisolated current-modePWM controllers ideal for flyback/forward topologies

85V AC to 265V AC universal offlineinput voltage range ( MAX17500),9.5V DC to 24V DC input voltagerange (MAX17499), programmableswitching frequency up to 625kHz,1.5% reference accuracy

Primary-side regulation eliminatesoptocouplers, allowing low-costisolated supplies.

MAX5069 Isolated/nonisolated currentmode PWM controller with dualFET drivers ideal for push-pull andhalf/full-bridge power supplies

85V AC to 265V AC universaloffline input voltage range(MAX5069A/B), 10.8V DC to24V DC input voltage range(MAX5069C/D), programmableswitching frequency up to 2.5MHz,programmable UVLO and UVLOhysteresis

Minimizes footprint due to widerange programmable switchingfrequency; programmableUVLO/hysteresis ensures properoperation during brownoutconditions.

MAX15062* High-voltage synchronous, microbuck regulator

4V to 36V input voltage range,fixed 700kHz switching frequency,

integrated high-side and low-sideFETs, internal compensation

Reduces total solution size andcost with high integration and

small package.

ADCs

MAX11044/45/46

MAX11047/48/49

16-bit, 4-/6-/8-channel,simultaneous-sampling SAR ADCs

93dB SNR: -105dB THD; 0 to 5Vor 5V inputs; parallel interfaceoutputs, all eight data results in250ksps; high-input impedance(> 1M)

High-impedance input savesthe cost and space of externalamplifier.

MAX1377/MAX1379/MAX1383 12-bit, dual, 1.25Msps,simultaneous-sampling SAR ADCs

0 to 5V, 0 to 10V, or 10V inputs:70dB SNR; SPI interface

Serial interface saves cost andspace on digital isolators.

MAX11040K 24-bit, 4-channel, simultaneous-sampling, sigma-delta ADC

117dB SNR, 64ksps, internalreference, SPI interface, 38-pinTSSOP package

Reduces motor control firmwarecomplexity.

MAX11203 16-bit single-channel, ultra-low-power, delta-sigma ADC

Programmable gain, GPIO, highresolution per unit power ratio

Eases achieving high-efficiencydesigns.

DACs

DS4432 Dual sink/source current DACwith sink and source settingsprogrammable via I 2C interface;range settable with resistors

50A to 200A sink/source range,127 sink, 127 source set tings

Provides simple and precise digitalspeed control for a wide range ofDC motor control applications.

Current-Sense Amplifiers

MAX34406 Quad current-sense amplifier withovercurrent threshold comparators

Unidirectional current sensing;fixed gains of 25, 50, 100, and200V/V;0.6% gain error; 2V to28V common-mode range

Wide dynamic range supportswide range of motor current-sensing applications.

MAX9918/19/20 -20V to +75V input range; uni/bidirectional current-senseamplifiers

0.6% max gain error, 120kHz -3dBBW, -40 C to +125 C operatingtemperature range

Wide dynamic range and highaccuracy supports wide range ofmotor current-sensing applications.

MAX9643 High-speed current-senseamplifier

15MHz bandwidth, -1.5V to +60Vinput range, 50V max VOS, -40

C to+125 C operating temperature range

Provides very fast response toquickly changing currents in motorcontrol applications.

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*Future productcontact the factory for availability.
http://www.maxim-ic.com/MAX17499http://www.maxim-ic.com/MAX17500http://www.maxim-ic.com/MAX17499http://www.maxim-ic.com/MAX5069http://www.maxim-ic.com/MAX5069http://www.maxim-ic.com/MAX5069http://www.maxim-ic.com/MAX15062http://www.maxim-ic.com/MAX11044http://www.maxim-ic.com/MAX11047http://www.maxim-ic.com/MAX1377http://www.maxim-ic.com/MAX11040Khttp://www.maxim-ic.com/MAX11203http://www.maxim-ic.com/DS4432http://www.maxim-ic.com/MAX34406http://www.maxim-ic.com/MAX9918http://www.maxim-ic.com/MAX9643http://www.maxim-ic.com/MAX9643http://www.maxim-ic.com/MAX9918http://www.maxim-ic.com/MAX34406http://www.maxim-ic.com/DS4432http://www.maxim-ic.com/MAX11203http://www.maxim-ic.com/MAX11040Khttp://www.maxim-ic.com/MAX1377http://www.maxim-ic.com/MAX11047http://www.maxim-ic.com/MAX11044http://www.maxim-ic.com/MAX15062http://www.maxim-ic.com/MAX5069http://www.maxim-ic.com/MAX5069http://www.maxim-ic.com/MAX5069http://www.maxim-ic.com/MAX17499http://www.maxim-ic.com/MAX17500http://www.maxim-ic.com/MAX17499


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131Motor Control: Recommended Solutions


Operational Amplifiers

MAX9617/18/19/20 High efficiency, zero drift, op ampswith low noise and RRIO

10V (max)VOS over time andtemperature range of -40C to+125C, 59A supply current,1.5MHz GBW, SC70 package

Allow sensing low-side motorcurrent with high accuracy at lowpower consumption.

MAX9943/44 38V precision, single and dual opamps

Wide 6V to 38V supply range, low100V (max) input offset voltage,drives 1nF loads

Wide operating voltage rangeand precision performance undermost capacitive loads providesignal processing in wide range ofapplications.

Hall-Effect Sensor Interface

MAX9621 Dual, 2-wire Hall-effect sensorinterface

Analog and filtered digitaloutputs, high-side current sense,60V capability, detects short toground fault

Integration eases motor controldesign.

Temperature Sensors

MAX31723 Digital thermostat with SPI/3-wireinterface No external components, -55Cto +125C measurement range,0.5C accuracy, configurable9- to 12-bit resolution, nonvolatilethermostat thresholds

Eases processor burden by storingtemperature thresholds internallyin nonvolatile memory.

MAX31855 Thermocouple-to-digital converter Cold-junction compensated; workswith K, J, N, T, or E types; 14-bit, SPIinterface; -270C to +1800C

Simplifies system design whileproviding flexibility for variousthermocouple types.

Variable Reluctance (VR) Sensor Interface

MAX9924MAX9927 Reluctance (VR or magnetic coil)sensor interfaces

Integrated precision amplifierand comparator for small-signaldetection, flexible thresholdoptions, differential input stage,zero-crossing detection

Improve performance byaccurately detecting position andspeed of motors and rotatingshafts.

MOSFET Drivers

MAX15012 Half-bridge gate driver for high-and low-side MOSFETs with 2Apeak source/sink current drive

UVLO, fast (35ns typ) and matched(8ns max) propagation delays,175V high-side MOSFET voltagecapability

Prevents MOSFET damage due tosupply brownout; allows higherfrequency switching applications;allows use in high voltageapplications.

MAX15024 Low-side, 4A MOSFET drivers Single/dual operation, 16nspropagation delay, high sink/source current, 1.9W thermallyenhanced TDFN package

Shrinks designs with smallpackage and allows fast switchingwith tightly matched propagationdelays.

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http://www.maxim-ic.com/MAX9617http://www.maxim-ic.com/MAX9943http://www.maxim-ic.com/MAX9621http://www.maxim-ic.com/MAX31723http://www.maxim-ic.com/MAX31855http://www.maxim-ic.com/MAX9924http://www.maxim-ic.com/MAX15012http://www.maxim-ic.com/MAX15024http://www.maxim-ic.com/MAX15024http://www.maxim-ic.com/MAX15012http://www.maxim-ic.com/MAX9924http://www.maxim-ic.com/MAX31855http://www.maxim-ic.com/MAX31723http://www.maxim-ic.com/MAX9621http://www.maxim-ic.com/MAX9943http://www.maxim-ic.com/MAX9617


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Interface Transceivers

MAX13448E Fault-protected RS-485 transceiver 80V fault protected, full-duplexoperation, 3V to 5.5V operation

Makes equipment more robustand tolerant of misconnectionfaults.

MAX14840E High-speed RS-485 transceiver 40Mbps data rates, 35kV (HBM)ESD tolerance, 3.3V, +125Coperating temperature, small 3mmx 3mm TQFN package

High receiver sensitivity andhysteresis extend cable lengths inharsh motor control environments.

MAX14770E PROFIBUS transceiver 35kV (HBM) ESD protection,-40C to +125C temperaturerange, small 3mm x 3mm TQFNpackage

Industrys highest ESD protectionmakes motor control more robust.

MAX13171E/3E/5E Multiprotocol data interfacechipset

Complete RS-232 and relatedprotocols equipment interfacesolution, up to 40Mbps, truefail-safe receivers, 15kV ESDprotection

Enable flexible interfaces with pin-selectable protocols.

MAX13051 CAN transceiver 80V fault protection, autobaud,ISO 11898 compatible, up to1Mbps, -40C to +125C operation

Provides robust industrial strengthCAN interface solution.

Voltage Supervisors

MAX16052/3 High-voltage supervisor Adjustable voltage thresholds andtimeout; VCC to 16V and open-drain output to 28V

Ease supervisory designs forindustrial applications with high-voltage capability.

MAX6495 72V overvoltage protector Protects against t ransients up to72V, small 6-pin TDFN-EP package

Increases system reliability bypreventing component damagefrom high-voltage transients.

Control Interfaces

MAX6816/17/18 Single, dual, octal switch

debouncer

15kV ESD (HBM) protection Assure high reliability, clean

pushbutton signal from motorcontrol panels.

MAX7370 Key-switch controller plus LEDbacklight drive with dimming

Up to 64-key, separate press/release codes, 14kV Air Gap ESD,LED drive with PWM dimmingcontrol and blink, optional GPIO

Enables high reliability keyboardscanning and display illuminationin one IC.

MAX16054 Pushbutton on/off controller withdebounce and ESD protection

Handles 25V input levels,15kV ESD, deterministic outputon power-up, no externalcomponents

Enables simple, robust controlpanel interface in small SOT23package.

MAX6971 16-port, 36V constant current LEDdriver

25Mb 4-wire serial interface,up to 55mA current per output,fault detection, high dissipation

package, -40C to +125Coperation

Eases design of robust controlpanel indicators.

UARTs

MAX3108 Serial UART, SPI, I2C compatible 24Mbps (max) data rate, 128-word FIFOs, automatic RS-485transceiver control, 4 GPIOs, 24-pinSSOP or small 3.5mm x 3.5mmTQFN packages

Reduces host controllerperformance requirements andcost.
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