DMOS driver for three-phase brushless DC motor

1 1/25L6235 September 2003nOPERATING SUPPLY VOLTAGE FROM 8 TO OUTPUT PEAK CURRENT ( DC)nRDS(ON) TYP. VALUE @ Tj = 25 CnOPERATING FREQUENCY UP TO 100 KHznNON DISSIPATIVE OVERCURRENT DETECTION AND PROTECTION nDIAGNOSTIC OUTPUTnCONSTANT tOFF PWM CURRENT CONTROLLERnSLOW DECAY SYNCHR. RECTIFICATIONn60 & 120 HALL EFFECT DECODING LOGICnBRAKE FUNCTIONnTACHO OUTPUT FOR SPEED LOOPnCROSS CONDUCTION PROTECTIONnTHERMAL SHUTDOWNnUNDERVOLTAGE LOCKOUTnINTEGRATED FAST FREEWEELING DIODESDESCRIPTIONThe L6235 is a DMOS Fully Integrated three -PhaseMotor driver with Overcurrent Protection. Realized in MultiPower-BCD technology, the devicecombines isolated DMOS Power Transistors withCMOS and bipolar circuits on the same chip. The device includes all the circuitry needed to drive athree-phase BLDC motor including: a three -phaseDMOS Bridge, a constant off time PWM Current Con-troller and the decoding logic for single ended hallsensors that generates the required sequence for thepower in PowerDIP24 (20+2+2), PowerSO36 andSO24 (20+2+2) packages, the L6235 features a non-dissipative overcurrent protection on the high sidePower MOSFETs and thermal DIAGRAMCHARGEPUMPVOLTAGEREGULATORHALL-EF FECTSENSORSDECODINGLOGICTHERMALPROTECTIO NTACHOMONOSTABLEOCD1 OCDOCDOCD210V5 VVCPVSAGATELOGICVBOOTVBOOTOUT1 OUT2 SENSEAVSBOUT3 SENSEBDIAGENFWD/REVBRAKEH3H1 RCPULSED99IN1095 BTACHORCOFFH2 OCD3 ONE SHOTMONOSTABLEMASKINGTIMEVBOOTOCD110 VVBOOTOCD210 VVBOOTOCD310 VSENSECOMPARATOR+-PWMVREFORDERING NUMBERS.

2 L6235NL6235 PDL6235 DPowerDIP24 (20+2+2)PowerSO36SO24 (20+2+2)DMOS driver FORTHREE-PHASE brushless DC MOTORL6235 2/25 ABSOLUTE MAXIMUM RATINGSRECOMMENDED OPERATING CONDITIONS ymbolParameterTest conditionsValueUnitVSSupply VoltageVSA = VSB = VS60 VVODD ifferential Voltage between:VSA, OUT1, OUT2, SENSEA and VSB, OUT3, SENSEBVSA = VSB = VS = 60V;VSENSEA = VSENSEB = GND60 VVBOOTB ootstrap Peak VoltageVSA = VSB = VSVS + 10 VVIN, VENL ogic Inputs Voltage to 7 VVREFV oltage Range at pin to 7 VVRCOFFV oltage Range at pin to 7 VVRCPULSEV oltage Range at pin to 7 VVSENSEV oltage Range at pins SENSEA and SENSEB-1 to 4 VIS(peak)Pulsed Supply Current (for each VSA and VSB pin)VSA = VSB = VS; TPULSE < Supply Current (for each VSA and VSB pin)VSA = VSB = , TOPS torage and Operating Temperature Range-40 to 150 CSymbolParameterTest ConditionsMINMAXUnitVSSupply VoltageVSA = VSB = VS1252 VVODD ifferential Voltage between:VSA, OUT1, OUT2, SENSEA and VSB, OUT3, SENSEBVSA = VSB = VS;VSENSEA = VSENSEB52 VVREFV oltage Range at pin Range at pins SENSEA and SENSEB(pulsed tW < trr)(DC)-6-161 VVIOUTDC Output CurrentVSA = VSB = Junction Temperature-25125 CfSWSwitching Frequency100 KHz3/25L6235 THERMAL DATAPIN CONNECTIONS (Top view)(5) The slug is internally connected to pins 1, 18, 19 and 36 (GND pins).

3 SymbolDescriptionPDIP24SO24 PowerSO36 UnitRth(j-pins)Maximum Thermal Resistance Junction-Pins1814 C/WRth(j-case)Maximum Thermal Resistance Junction-Case1 C/WRth(j-amb)1 MaximumThermal Resistance Junction-Ambient (1)(1) Mounted on a multi-layer FR4 PCB with a dissipating copper surface on the bottom side of 6 cm2 (with a thickness of 35 m).4351- C/WRth(j-amb)1 Maximum Thermal Resistance Junction-Ambient (2)(2) Mounted on a multi-layer FR4 PCB with a dissipating copper surface on the top side of 6 cm2 (with a thickness of 35 m).--35 C/WRth(j-amb)1 MaximumThermal Resistance Junction-Ambient (3)(3) Mounted on a multi-layer FR4 PCB with a dissipating copper surface on the top side of 6 cm2 (with a thickness of 35 m), 16 via holes and a ground C/WRth(j-amb)2 Maximum Thermal Resistance Junction-Ambient (4)(4) Mounted on a multi-layer FR4 PCB without any heat-sinking surface on the C/ (5)PowerDIP24/SO24L6235 4/25 PIN DESCRIPTION PACKAGENameTypeFunctionSO24/PowerDIP24 PowerSO36 PIN #PIN #110H1 Sensor InputSingle Ended Hall Effect Sensor Input Drain OutputOvercurrent Detection and Thermal Protection pin.

4 Aninternal open drain transistor pulls to GND when anovercurrent on one of the High Side MOSFETs isdetected or during Thermal Supply Half Bridge 1 and Half Bridge 2 Source Pin. This pinmust be connected together with pin SENSEB toPower Ground through a sensing power PinRC Network Pin. A parallel RC network connectedbetween this pin and ground sets the CurrentController Output Output 16, 7,18, 191, 18,19, 36 GNDGNDG round terminals. On PowerDIP24 and SO24packages, these pins are also used for heatdissipation toward the PCB. On PowerSO36 packagethe slug is connected on these Drain OutputFrequency-to-Voltage open drain output. Every pulsefrom pin H1 is shaped as a fixed and adjustable PinRC Network Pin. A parallel RC network connectedbetween this pin and ground sets the duration of theMonostable Pulse used for the Supply Half Bridge 3 Source Pin.

5 This pin must be connectedtogether with pin SENSEA to Power Ground through asensing power resistor. At this pin also the InvertingInput of the Sense Comparator is InputSelects the direction of the rotation. HIGH logic levelsets Forward Operation, whereas LOW logic level setsReverse Operation. If not used, it has to be connected to GND or + InputChip Enable. LOW logic level switches OFF all not used, it has to be connected to + InputCurrent Controller Reference Voltage. Do not leave this pin open or connect to InputBrake Input pin. LOW logic level switches ON all HighSide Power MOSFETs, implementing the not used, it has to be connected to + Voltage Bootstrap Voltage needed for driving the upper Output Output Supply Half Bridge 3 Power Supply Voltage. It must beconnected to the supply voltage together with pin #PIN #204 VSAP ower Supply Half Bridge 1 and Half Bridge 2 Power Supply must be connected to the supply voltage togetherwith pin Output Output Pump Oscillator InputSingle Ended Hall Effect Sensor Input InputSingle Ended Hall Effect Sensor Input CHARACTERISTICS (VS = 48V , Tamb = 25 C , unless otherwise specified)SymbolParameter Test ConditionsMinTypMax UnitVSth(ON)Turn ON (OFF)Turn OFF Supply CurrentAll Bridges OFF;Tj = -25 to 125 C (6)510mATJ(OFF)Thermal Shutdown Temperature165 COutput DMOS TransistorsRDS(ON)High-Side Switch ON ResistanceTj = 25 Tj =125 C (6) Low-Side Switch ON ResistanceTj = 25 Tj =125 C (6) IDSSL eakage CurrentEN = Low; OUT = VCC2mAEN = Low.

6 OUT = Drain DiodesVSDF orward ON VoltageISD = , EN = Recovery TimeIf = Recovery Time200nsLogic Input (H1, H2, H3, EN, FWD/REV, BRAKE)VILLow level logic input level logic input voltage27 VIILLow level logic input currentGND Logic Input Voltage-10 AIIHHigh level logic input current7V Logic Input Voltage10 AVth(ON)Turn-ON Input (OFF)Turn-OFF Input Thresholds DESCRIPTION (continued)L6235 6/25(6) Tested at 25 C in a restricted range and guaranteed by characterization.(7) See Fig. 1.(8) Measured applying a voltage of 1V to pin SENSE and a voltage drop from 2V to 0V to pin VREF.(9) See Fig. Test ConditionsMinTypMax UnitSwitching CharacteristicstD(on)ENEnable to out turn-ON delay time (7)ILOAD = A, Resistive Load110250400nstD(off)ENEnable to out turn-OFF delay time (7)ILOAD = A, Resistive Load300550800nstD(on)INOther Logic Inputs to Output Turn-ON delay TimeILOAD = A, Resistive Load2 stD(off)INOther Logic Inputs to out Turn-OFF delay TimeILOAD = A, Resistive Load2 stRISEO utput Rise Time (7)ILOAD = A, Resistive Load40250nstFA L LOutput Fall Time (7)ILOAD = A, Resistive Load40250nstDTDead sfCPCharge Pump FrequencyTj = -25 to 125 C (6) Comparator and MonostableIRCOFFS ource current at pin RCOFF VRCOFF = Voltage on Sense ComparatorVref = V 5mVtpropTurn OFF Propagation delay (8)Vref = V500nstblankInternal Blanking Time on Sense Comparator1 stON(min)

7 Minimum on stOFFPWM RecirculationTimeROFF= 20k ; COFF =1nF13 sROFF= 100k ; COFF =1nF61 sIBIASI nput Bias Current at pin VREF 10 ATacho MonostableIRCPULSES ource Current at pin RCPULSEVRCPULSE = of TimeRPUL = 20k ; CPUL =1nF12 sRPUL = 100k ; CPUL =1nF60 sRTACHOOpen Drain ON Resistance4060 Over Current Detection & ProtectionISOVERS upply Overcurrent Protection ThresholdTJ = -25 to 125 C (6) Drain ON ResistanceIDIAG = 4mA4060 IOHOCD high level leakage currentVDIAG = 5V1 AtOCD(ON)OCD Turn-ON Delay Time (9)IDIAG = 4mA; CDIAG < 100pF200nstOCD(OFF)OCD Turn-OFF Delay Time (9)IDIAG = 4mA; CDIAG < 100pF100nsELECTRICAL CHARACTERISTICS (continued)(VS = 48V , Tamb = 25 C , unless otherwise specified)7/25L6235 Figure 1. Switching Characteristic DefinitionFigure 2. Overcurrent Detection Timing DefinitionVth(ON)Vth(OFF)90%10%ENIOUTttt FALLtD(OFF)ENtRISEtD(ON)END01IN1316 ISOVER90%10%IOUTVDIAGtOCD(OFF)tOCD(ON)D0 2IN1387 ONOFFBRIDGEL6235 8/25 CIRCUIT DESCRIPTIONPOWER STAGES and CHARGE PUMPThe L6235 integrates a three -Phase Bridge, whichconsists of 6 Power MOSFETs connected as shownon the Block Diagram.

8 Each Power MOS has anRDS(ON) = (typical value @25 C) with intrinsicfast freewheeling diode. Switching patterns are gen-erated by the PWM Current Controller and the HallEffect Sensor Decoding Logic (see relative para-graphs). Cross conduction protection is implementedby using a dead time (tDT = 1 s typical value) set byinternal timing circuit between the turn off and turn onof two Power MOSFETs in one leg of a VSA and VSB MUST be connected together tothe supply voltage (VS).Using N-Channel Power MOS for the upper transis-tors in the bridge requires a gate drive voltage abovethe power supply voltage. The Bootstrapped Supply(VBOOT) is obtained through an internal oscillator andfew external components to realize a charge pumpcircuit as shown in Figure 3. The oscillator output (pinVCP) is a square wave at 600 KHz (typically) with 10 Vamplitude. Recommended values/part numbers forthe charge pump circuit are shown in 1.

9 Charge Pump External 3. Charge Pump CircuitLOGIC INPUTSPins FWD/REV, BRAKE, EN, H1, H2 and H3 are TTL/CMOS and C compatible logic inputs. The internalstructure is shown in Figure 4. Typical value for turn-ON and turn-OFF thresholds are respectively Vth(ON)= and Vth(OFF) = EN (enable) may be used to implement Overcurrentand Thermal protection by connecting it to the open col-lector DIAG output If the protection and an external dis-able function are both desired, the appropriateconnection must be implemented. When the externalsignal is from an open collector output, the circuit in Fig-ure 5 can be used . For external circuits that are pushpull outputs the circuit in Figure 6 could be used. The re-sistor REN should be chosen in the range from to180K . Recommended values for REN and CEN are re-spectively 100K and More information for se-lecting the values can be found in the OvercurrentProtection 4.

10 Logic Input Internal StructureFigure 5. Pin EN Open Collector DrivingFigure 6. Pin EN Push-Pull DrivingCBOOT220nFCP10nFRP100 D11N4148D21N4148D2 CBOOTD1 RPCPVSVSAVCPVBOOTVSBD01IN13285VD01IN1329 ESDPROTECTION5V5 VOPENCOLLECTOROUTPUTRENCENENDIAGD02IN137 8 ESDPROTECTION5 VPUSH-PULLOUTPUTRENCENEND02IN1379 DIAGESDPROTECTION9/25L6235 PWM CURRENT CONTROLThe L6235 includes a constant off time PWM Current Controller. The current control circuit senses the bridgecurrent by sensing the voltage drop across an external sense resistor connected between the source of thethree lower power MOS transistors and ground, as shown in Figure 7. As the current in the motor increases thevoltage across the sense resistor increases proportionally. When the voltage drop across the sense resistor be-comes greater than the voltage at the reference input pin VREF the sense comparator triggers the monostableswitching the bridge off. The power MOS remain off for the time set by the monostable and the motor currentrecirculates around the upper half of the bridge in Slow Decay Mode as described in the next section.