Low Power PWM Controller With On-Chip Power Switch
NCP1032Low Power PWM Controllerwith On-Chip Power SwitchThe NCP1032 is a miniature high voltage monolithic switchingconverter with on chip power switch and startup circuits. Itincorporates in a single IC all the active power control logic andprotection circuitry required to implement, with minimal externalcomponents several switching regulator applications, such as asecondary side bias supply or a low power DC DC converter. Thisconverter is ideally suited for 24 V and 48 V telecom and medicalisolated power supply applications. The NCP1032 can be configuredin any single ended topology such as forward or flyback converter.The NCP1032 is targeted for applications requiring up to 3 W.The internal error amplifier allows the NCP1032 to be easilyconfigured for secondary or primary side regulation operation inisolated and non isolated configurations. The fixed frequencyoscillator is optimized for operation up to 1 MHz and is capable ofexternal frequency synchronization, providing additional designflexibility. In addition, the NCP1032 incorporates undervoltage andovervoltage line detectors, programmable cycle by cycle currentlimit, internal soft start, and thermal shutdown to protect thecontroller under fault conditions.www.onsemi.comMARKINGDIAGRAMSWDFN8MN SUFFIXCASE 511BH11032xALYW GG1032 Specific Device Markingx A or BA Assembly LocationL Wafer LotY YearW Work WeekG Pb Free Package(Note: Microdot may be in either location)Features On Chip High 200 V Power Switch Circuit and Startup CircuitInternal Startup Regulator with Auxiliary Winding OverrideProgrammable Oscillator Frequency Operation up to 1 MHzExternal Frequency Synchronization CapabilityFrequency Fold down Under Fault ConditionsTrimmed 2% Internal ReferenceProgrammable Cycle by Cycle Current LimitInternal Soft StartActive Leading Edge Blanking CircuitLine Under and Over Voltage ProtectionOver Temperature ProtectionThese are Pb Free DevicesPIN AINGNDVCCUV/OVCLWDFN8 (Top View)ORDERING INFORMATIONSee detailed ordering and shipping information in the packagedimensions section on page 20 of this data sheet.Typical Applications POE (Power Over Ethernet)/PD. Refer to Application Note AND8247Secondary Side Bias Supply for Isolated DC DC ConvertersStand Alone Low Power DC DC ConverterLow Power Bias SupplyLow Power Boost ConverterMedical Isolated Power SuppliesBias Supply for Telecom Systems. Refer to App Note AND8119/D Semiconductor Components Industries, LLC, 2014August, 2019 Rev. 31Publication Order Number:NCP1032/D
NCP1032VOUTVIND1Cin2.2 mFCOUT22 mFD2CVCC2.2 mFUV/OVVDRAINR3VCCCLRCLR4CCNCP 1032RCGNDCTCOMPCPR1VFBR2CCTFigure 1. Typical Application – Dual Output Auxiliary Regulated Isolated FlybackPGNDVDRAINInternal BiasI1150 kWDriverLEBLEBOUT2 kWUVBARDutyCycle 75%3.0 V/3.5 VUVBARFaultCOMPOV/UV2.5 V2 kWOVComp 2.24 V 1.0 V UVCompQSQSETR30 nsOne ShotPWMCOMP ErrorAmplifier 2 kWNLOWVCCDelayCLRFBVCC6.6 VI22 kW12.5 mAnstartNUVLORT2 kW 5.7 VNUVHIVCC10.2 VInternal Bias2 kWNSSLEBOUTNCL3.5 VNOV7.6 VFaultIN1 LogicIN2IN3IN4 OUT2IN5 OUT3IN6IN7NUVLOUVBARNLOWVCCNUVHIVCCNOVThermal TripInternal BiasFaultnstartCurrentLimitSS(all pins except VDRAIN pin are protected by 10 V ESD diodes)Figure 2. NCP1032 Simplified Block Diagramwww.onsemi.com2FaultISET
NCP1032Table 1. FUNCTIONAL PIN DESCRIPTIONPinNameFunction1GNDIC GroundDescription2CTOscillator FrequencySelection3VFBFeedback Signal InputThe regulated voltage is scaled down to 2.5 V by means of a resistor divider. Regulation isachieved by comparing the scaled voltage to an internal 2.5 V reference.4COMPError AmplifierCompensationThe output of the internal error amplifier. External compensation network between COMPand VFB pin is required for stable operation.5CLCurrent Limit ThresholdSelectionA resistor RCL connected between this pin and ground sets the peak current value of thecurrent limit. If the CL pin is left open, the current limit value is set to its initial maximum valueof approximately 12 mA (CLIM MAX). Programmable current limit threshold, together withinternal soft start feature effectively limits the primary transformer high current peaks duringstartup phase.6UV/OVInput Line Undervoltageand OvervoltageShutdownInput line voltage is scaled down using an external resistor divider. The minimum operatingVin voltage is achieved when the voltage on UV/OV pin reaches UV threshold 1.0 V. Themaximum operating voltage is then limited by 2.4 V on UV/OV pin. A device version withoutOV protection feature is available, see ordering information section.7VCCPowers the InternalCircuitry8VDRAINDrain ConnectionEPEPThermal FlagGround reference pin for the circuit.An external capacitor connected to this pin sets the oscillator frequency up to 1 MHz. Theoscillator can be synchronized to a higher frequency by charging or discharging CT to trip theinternal 3.0 V/3.5 V comparators. If a fault condition exists, the power switch is disabled andthe frequency is reduced.Supplies power to the internal control circuitry. Connect an external capacitor for energystorage during startup. The Vcc voltage should not exceed 16 V during operation.Connects the power switch and startup circuit to the primary transformer windings.This is the thermal flag for the IC and should be soldered to the ground plane.Table 2. MAXIMUM RATINGSRatingSymbolValueUnitBVdss 0.3 to 200VVCC Power Supply VoltageVCC 0.3 to 16VPower Supply Voltage on all Pins, except VDRAIN and VCCVIO 0.3 to 10VIDS(pk)1.0APower Switch and Startup Circuits VoltageDrain Current Peak During Transformer SaturationThermal Resistance Junction to Air –W DFN8 3x3, case 511BH(100 sq mm, 2oz) (Note 4)(500 sq mm, 2oz) (Note 4)(100 sq mm,2oz,) (Note 5)RqJA1096444 C/WMaximum Junction TemperatureTJMAX150 CStorage Temperature RangeTSTG 60 to 150 CESD Capability, Human Body Model Pins 1 7 (Note 1)4.0kVESD Capability, Machine Model Pins 1 7 (Note 1)400VPin 8 is connected to the high voltage startup and power switch which is protected tothe maximum drain voltage200VStresses exceeding those listed in the Maximum Ratings table may damage the device. If any of these limits are exceeded, device functionalityshould not be assumed, damage may occur and reliability may be affected.1. This device series contains ESD protection and passes the following tests:Human Body Model (HBM) 2.0 kV per JEDEC standard: JESD22 A114.Machine Model (MM) 200 V per JEDEC standard: JESD22 A115.2. This device contains latch up protection and it exceeds 100 mA per JEDEC standard: JESD78 class II3. Moisture Sensitivity Level (MSL): 1 per IPC/JEDEC standard: J STD 020A4. EIA JEDEC 51.3, single layer PCB with added heat spreader5. EIA JEDEC 51.7, four layer PCB with added heat spreaderwww.onsemi.com3
NCP1032Table 3. ELECTRICAL CHARACTERISTICS(For typical values Tj 25 C, for min/max values Tj 40 C to 125 C, VDRAIN 48 V, VCC 12 V, unless otherwise noted)SymbolParameterConditionsMinTypMaxUnitSUPPLY SECTION AND VCC MANAGEMENTVCC ONVcc Voltage at Which the SwitcherStarts OperationVCC Increasing9.910.210.5VVCC MINMinimum Operating VCC After Turn onat Which HV Current Source RestartsVCC Decreasing7.407.557.7VVCC RSTVcc Undervoltage Lockout VoltageVCC Decreasing, VFB VCOMP6.756.957.15VICC1Internal IC ConsumptionPower Switch EnabledMOSFET is switching at 300 kHz2.02.94.0mAICC2Internal IC ConsumptionPower Switch DisabledNo Fault condition, VFB 2.7 V 2.02.5mAICC3Internal IC ConsumptionPower Switch DisabledFault condition,VFB 2.7 V, VUV/OV 1.0 V 0.751.5mA 4.24.95.18.0200 20202530POWER SWITCH CIRCUITRDSONPower Switch Circuit On StateResistanceID 100 mATJ 25 CTJ 125 CBVdssPower Switch Circuit and StartupBreakdown VoltageIDS OFF 100 mA, VUV OV 1.0 VTj 25 CIDS OFFPower Switch Circuit and StartupCircuit Off State Leakage CurrentVDRAIN 200 V, VUV OV 1.0 VTJ 25 CTJ 40 C to 125 CtRSwitching Characteristics Rise TimeVDS 48 V, RL 480 W, Time(10% 90%) 7 nstfSwitching Characteristics Fall TimeVDS 48 V, RL 480 W, Time(90% 10%) 10 nsWVmAINTERNAL STARTUP CURRENT SOURCEISTART1HV Current SourceVcc 0 V,Tj 25 CTj 40 C to 125 C10.09.012.0 14.015.0ISTART2HV Current SourceVcc VCC ON 0.2 VTj 25 CTj 40 C to 125 C9.08.011.0 13.016.0Minimum Startup VoltageISTART2 0.5 mA,Vcc VCC ON 0.2 V, Tj 25 C 16.3 Vstart minmAmAVERROR AMPLIFIERVREFREGLINEReference VoltageVCOMP VFB, Follower ModeTJ 25 CTJ 40 C to 125 C2.452.402.52.52.552.60VLine RegulationVCC 8 V to 16 V, TJ 25 C 1.03.0mVIVFBInput Bias CurrentVFB 2.3 V 70150nAISRCCOMP Source CurrentVFB 2.3 V8095125mAISNKCOMP Sink CurrentVFB 2.7 V500700900mAVC MAXCOMP Maximum VoltageISRC 0 mA, VFB 2.3 V3.954.174.5VVC MINCOMP Minimum VoltageISNK 0 mA, VFB 2.7 V 91200mVAVOLOpen Loop Voltage Gain(Note 6) 80 dBGBWGain Bandwidth Product(Note 6) 1.0 MHzwww.onsemi.com4
NCP1032Table 3. ELECTRICAL CHARACTERISTICS(For typical values Tj 25 C, for min/max values Tj 40 C to 125 C, VDRAIN 48 V, VCC 12 V, unless otherwise noted)SymbolParameterConditionsMinTypMax420512600 57 UnitCURRENT LIMIT AND PWM COMPARATORCLIM MAXMax Current Limit ThresholdCL pin Floating, TJ 25 C,(di/dt 0.5 A/ms)CLIM MINMin Current Limit ThresholdRCL 20 kW, TJ 25 C,(di/dt 0.1 A/ms)Propagation Delayfrom Current Limit Detection to theDrain OFF State (Note 6) 100 nsMin On Time Pulse WidthFSW 300 kHz (Note 6) 240 nsSoft Start Duration(Note 6) 2.0 ms0.951.0671.18V 70 mV 01mA2.32.412.5V 158 mVTPLHTON MINTssmAmALINE UNDER/OVERVOLTAGE PROTECTIONSVuvUndervoltage Lockout ThresholdVUV hysUndervoltage Lockout HysteresisVFB VCOMP, Vin decreasingIuvInput Bias CurrentVFB 2.3 VVOVOvervoltage Lockout ThresholdVFB VCOMP, Vin increasing (Note 7)Vov hysOvervoltage Lockout HysteresisTEMPERATURE MANAGEMENTTSDThermal Shutdown(Note 6)165 CHysteresis in Shutdown(Note 6)20 CINTERNAL OSCILLATORfOSC1Oscillation Frequency, 300 kHzCT 560 pF (Note 8)TJ 25 CTJ 40 C to 125 C275270300 325335fOSC2Oscillation Frequency, 960 kHzCT 100 pF, TJ 25 C 960 kHzICT CTiming Charge CurrentVCT 3.25 V 172 mAICT DTiming Discharge CurrentVCT 3.25 VVR pkOscillator Ramp Peak Voltage 3.492 VVR VLYOscillator Ramp Valley 2.992 VDCMAxMaximum Duty Cycle7076.580%517kHzmAProduct parametric performance is indicated in the Electrical Characteristics for the listed test conditions, unless otherwise noted. Productperformance may not be indicated by the Electrical Characteristics if operated under different conditions.6. Guaranteed by design and characterized7. The OV/UV option is disabled on the NCP1032B version8. Oscillator frequency can be externally synchronized to the maximum frequency of the devicewww.onsemi.com5
NCP1032TYPICAL OPERATING CHARACTERISTICS – Dual Output Isolated Flyback Converter12.1008018 V12.09572 V12.0906048 V5036 VVOUT (V)EFFICIENCY (%)7024 17520012.06022548 V24 V12.08572 V18 V36 V0255075100125150175200 225IOUT (mA)IOUT (mA)Figure 3. Efficiency vs. IOUT at VIN 24, 36, 48and 72 V, T1 CoilCraft B0226 ELFigure 4. VCC Pin Load Regulation at VIN 24,36, 48 and 72 VFigure 5. Startup Sequence, RCL Open, OutputLoad 80 W (IOUT 150 mA), 1 VCC 3.0 V/div DC, 2 VOUT 3.0 V/div DC, 3 VIN 10.0 V/div DC, 4 IPRI 100 mA/div DC, T 20 ms/divFigure 6. Soft Start, RCL open, Output NoLoad 1 VCC 3.0 V/div DC, 2 VOUT 3.0 V/div DC,3 VIN 10.0 V/div DC, 4 IPRI 100 mA/div DC,T 500 ms/divFigure 7. Soft Start, RCL 32 kW (CLIM 250 mA), Output Load 240 W (IOUT 50 mA),1 VCC 3.0 V/div DC, 2 VOUT 3.0 V/div DC, 3 VIN10.0 V/div DC, 4 IPRI 100 mA/div DC,T 1.0 ms/divFigure 8. Discontinuous Conduction Mode(DCM), IOUT 150 mA, 2 VDRAIN 20 V/div DC,3 ISEC 30 mA/div DC, 4 IPRI 100 mA/div, DC,T 500 ns/divwww.onsemi.com6
NCP1032TYPICAL OPERATING CHARACTERISTICS1100SWITCHING FREQUENCY (kHz)1600FREQUENCY (kHz)8004002001005080560104015202000700CT 220 pF6005004002480CT 560 pF 20020406080100 120AMBIENT TEMPERATURE ( C)Figure 9. Frequency vs. Timing Capacitor CTat 255CFigure 10. Oscillator Frequency vs. JunctionTemperature75.5VDRAIN 100 V597 kHz320 kHz75.675.21.04 MHz75.4DUTY CYCLE (%)DUTY CYCLE (%)800CAPACITANCE (pF)75.875.275.0128 kHz74.874.674.4VDRAIN 48 V74.9VDRAIN 15 V74.674.3 2002040608010089101112131415AMBIENT TEMPERATURE ( C)VCC (V)Figure 11. Maximum Duty Ratio vs.TemperatureFigure 12. Maximum Duty Ratio vs. VCCVoltage300280260VDRAIN 15 V240220200VDRAIN 48 V180160140VDRAIN 100 V874.0120910111213141516IDS(off), POWER SWITCH AND STARTUPCIRCUITS LEAKAGE CURRENT (mA)74.274.0 40MIN ON TIME (ns)900300 4076.0120100CT 82 pF100030282624222018161412108642016125 C25 C 40 C04080120160200240VCC (V)DRAIN VOLTAGE (V)Figure 13. Minimum On Time vs. VCCFigure 14. Power Switch Circuit and StartupCircuit Leakage Current vs. Drain Voltagewww.onsemi.com7
NCP10325.55.35.14.94.74.54.34.13.93.73.53.33.12.9 40VCC 8 VVCC 12 VVCC 16 V 20020406080100VCC(reset), UNDERVOLTAGELOCKOUT THRESHOLD (V)RDS(on), POWER SWITCH ONRESISTANCE (W)TYPICAL OPERATING .2816.2616.2416.2216.2016.1816.1616.1416.1216.10 40 20TJ, JUNCTION TEMPERATURE ( C)6080100120VCC(reset), UNDERVOLTAGELOCKOUT THRESHOLD (V)6.965VCC 0 VVCC VCC(on) 0.2 V 200204060801006.9606.9556.9506.9456.9406.9356.930 40120 20020406080100120TJ, JUNCTION TEMPERATURE ( C)TJ, JUNCTION TEMPERATURE ( C)Figure 17. Startup Current vs. JunctionTemperatureFigure 18. Undervoltage Lockout Thresholdvs. Junction TemperatureStartup ThresholdINPUT CURRENT (mA)ISTART, STARTUP CURRENT (mA)40Figure 16. Vdrain Startup Threshold overTemperatureUV THRESHOLD 7.757.507.25 4020TJ, JUNCTION TEMPERATURE ( C)Figure 15. Power Switch RDSON vs. 411.211.010.810.610.410.2 400Minimum Operating Threshold .253.002.752.502.252.00100 200 300400500600700800 900 1000TJ, JUNCTION TEMPERATURE ( C)FREQUENCY (kHz)Figure 19. Supply Voltage Thresholds vs.Junction TemperatureFigure 20. VCC Input Current at 12 V with an18 V applied Drain voltage 255C VS OscillatorFrequencywww.onsemi.com8
NCP1032TYPICAL OPERATING 11213145.04.5597 kHz4.03.5320 kHz3.0128 kHz2.0 401615020406080100120AMBIENT TEMPERATURE ( C)Figure 21. Operating Supply Current vs.Supply Voltage at 320 kHzFigure 22. VCC Input Current vs. Temperatureover Frequency span VDrain 48 V4.204.194.184.174.164.154.144.134.124.11 40 20VCC, SUPPLY VOLTAGE (V)REFERENCE VOLTAGE (V)Vc CLAMP (V)5.52.54.234.224.21 200204060801002.5002.4992.4982.4952.494VCC 12 VVCC 8 V2.4932.4922.4912.4902.4892.488 40120VCC 16 V2.4972.496 20020406080100TJ, JUNCTION TEMPERATURE ( C)TJ, JUNCTION TEMPERATURE ( C)Figure 23. COMP Clamp Voltage vs. JunctionTemperatureFigure 24. Reference Voltage vs. JunctionTemperature12080096.5096.25780VCC 16 V96.0095.75SINK CURRENT (mA)SOURCE CURRENT (mA)1.04 MHz6.0INPUT CURRENT (mA)ICC1, OPERATING SUPPLYCURRENT (mA)6.5VDRAIN 48 VTJ 25 CCT 560 pF3.9VCC 12 V95.5095.2595.00VCC 8 V94.7594.5094.2594.00 40760740720700680660640 20020406080100120620 40 20020406080100TJ, JUNCTION TEMPERATURE ( C)TJ, JUNCTION TEMPERATURE ( C)Figure 25. COMP Source Current vs. JunctionTemperatureFigure 26. COMP Sink Current vs. JunctionTemperaturewww.onsemi.com9120
NCP1032TYPICAL OPERATING CHARACTERISTICSVCC 16 V1.0701.069OV THRESHOLD (V)UV THRESHOLD (V)1.0721.071VCC 8 V1.0681.0671.066VCC 12 V1.0651.0641.0631.062 20020406080120100UV Hysteresis 1501005020406080100120140160180 200TJ, JUNCTION TEMPERATURE ( C)RISET (kW)Figure 29. Under/Overvoltage Hysteresis vs.Junction TemperatureFigure 30. Current Limit Threshold vs. RCL,Current Slew Rate 0.5 A/ms34033025 V72 V120 mH3103002902800ILIM, CURRENT LIMIT THRESHOLD (mA)110100270 20Figure 28. Overvoltage Threshold vs. JunctionTemperature140130120320VCC 12 VFigure 27. Undervoltage Threshold vs.Junction TemperatureOV Hysteresis90807060 40VCC 8 VTJ, JUNCTION TEMPERATURE ( C)180170160150VCC 16 VTJ, JUNCTION TEMPERATURE ( C)100 200 300 400 500 600 700 800 900 1000ILIM, CURRENT LIMIT THRESHOLD (mA)ILIM, CURRENT LIMIT THRESHOLD (mA)VUV/OV(hys), HYSTERESIS (mV)1.0611.060 042.4022.4002.3982.3962.394 40550500RISET OPEN450400350300RISET 50 kW25020015010050 40RISET 22 kW 20020406080100120CURRENT SLEW RATE (mA/mS)TJ, JUNCTION TEMPERATURE ( C)Figure 31. Current Limit Threshold vs. CurrentSlew RateFigure 32. Current Limit Threshold vs. TJ,Current Slew RISET Open 0.5 A/ms, RISET 55 kW 0.3 A/ms, RISET 22 kW 0.1 A/mswww.onsemi.com10
NCP1032CT RampCT ChargeSignalPWMComparatorOutputCurrent LimitPropagationDelayPWM LatchOutputPower SwitchCircuit Gate DriveCurrent LimitThresholdLeading EdgeBlanking OutputNormal PWM Operating RangeOutput OverloadFigure 33. Pulse Width Modulation Timing DiagramVCC(on)VCC(off)VCC(reset)0VISTART0 mA3.0 VVUV0V2.5 VVFB0VVDRAIN0VStartupModeDynamicSelf SupplyNormal OperationOutput OverloadFigure 34. Auxiliary Winding Operation with Output Overload Timing Diagramwww.onsemi.com11
NCP1032Introductionits minimum value to its maximum value. The soft starttime is load and RCL dependent and can be computed in thesoft start section. The designer must evaluate the currentdraw of the regulator at the desired switching frequency overthe VCC and temperature operating range shown in Figures20 22. CVCC is calculated using the following equation:The NCP1032 is a monolithic voltage mode switchingregulator designed for isolated and non isolated bias supplyapplications. The internal startup circuit and the MOSFETare rated at 200 V, making them ideal for 24 V through 48 Vtelecom and 42 V automotive applications. In addition, theNCP1032 can operate from an existing 12 V supply. Theregulator is optimized for operation up to 1 MHz.The NCP1032 device incorporates all of the active power,control logic, protection circuitry, and power switch in asingle IC. The compact design allows the designer to useminimal external components on several switchingregulator applications, such as a secondary side bias supplyor a low power DC DC converter.The NCP1032 is available in the space saving WDFN83 x 3 mm package and is targeted for applications requiringup to 3 W.The NCP1032 has an extensive set of features includingprogrammable cycle by cycle current limit, internalsoft start, input line under and over voltage detectioncomparators with hysteresis, regulator output undervoltagelockout with hysteresis and over temperature protectionproviding protection during fault conditions. A descriptionof each of the functional blocks is given below and thefunctional block diagram is shown in Figure 2.C VCC ǒTSS Delay ) TSSǓI CCV CC ON * V CC MIN2.95 mF ³(eq. 1)ǒ0.4 ms ) 2.0 msǓ4.0 mA10.2 V * 6.95 VICC includes the NCP1032 bias current (ICC1 MAX) andany additional current used to bias the feedback (if used).Assuming an ICC1 MAX of 3.5 mA plus a 0.5 mA biascurrent for the feedback sensing resistors (if used), and Tssof 2 ms, CVCC is calculated at 2.95 mF and should be roundedup to ensure design margin to 3.3 mF. Please note that if thefeedback sensing resistors are connected to the VCC pin(isolated main output topology) and CVCC is increased tomatch COUT, the transient response of the converter willsuffer. The poor transient response is due to the imbalancedcapacitance to current ratio. The auxiliary winding has asignificantly greater capacitance to current ratio than theoutput winding, taking it longer for CVCC to follow COUTduring a transient condition.After initial startup, the VCC pin should be biased aboveVCC min using an auxiliary winding. This will prevent thestartup regulator from turning on during normal operation,reducing device power dissipation. A load should not bedirectly connected to the VCC pin. A load greater than12 mA will override the startup circuit possibly damagingthe part. The maximum voltage rating of the startup circuitis 200 V. Power dissipation should be observed to avoidexceeding the maximum power dissipation of the package.Figure 35 shows the recommended configuration for anon isolated flyback converter.Startup Supply Circuit and Undervoltage LockoutThe NCP1032 contains an internal 200 V startup regulatorthat eliminates the need for external startup components.The startup regulator consists of a 12 mA (typical) currentsource that supplies power from the input line (VDRAIN)pin to charge the capacitor on the VCC pin (CVCC). The actof charging the CVCC capacitor until it reaches 10.2 V whileholding the power switch off is called Startup Mode (SM).Once the current source charges the VCC voltage to 10.2 V(typical) the startup circuit is disabled and if no faults arepresent, the power switch circuit is enabled. The internalcontrol circuitry will draw its current from the energy heldby the CVCC capacitor. The startup regulator turns on againonce VCC reaches 7.55 V. The charging of the CVCCcapacitor to 10.2 V by the current source and the dischargingby the control circuitry to 7.55 V will be henceforth referredto as Dynamic Self Supply (DSS).If VCC falls below 7.55 V while switching, the deviceenters a Restart Mode (RM). While in the RM the CVCCcapacitor is allowed to discharge to 6.95 V while the powerswitch is enabled. Once the 6.95 V threshold is reached, thepower switch circuit is disabled, and the startup regulator isenabled to charge the CVCC capacitor. The power switch isenabled again once the VCC voltage reaches 10.2 V.Therefore, the external CVCC capacitor must be sized suchthat a voltage greater than 6.95 V is maintained on the VCCpin while the converter output reaches regulation. Theoutput is delayed 0.4 ms (TSS Delay) from the releasedundervoltage lockout to the first switching pulse. Thesoft start time TSS is fixed at 2 ms to ramp the current DUV/OVVDRAINR3VCCCLRCLCCRCR1COMPVFBCPNCP1032Figure 35. Non Isolated Bias SupplyConfigurationwww.onsemi.com12R2
NCP1032Soft Startand the soft start time will be 2 ms as shown in Figure 36.The equation below can be used to calculate the soft starttime for all other current limit set values.The NCP1032 features an internal soft start whichreduces power on stress and also contributes to the loweroutput overshoot. Once the VCC ON threshold is reachedand there are no fault conditions, the power switch is enabledand the cycle by cycle current limit is ramped up slowly tothe current limit threshold set by the CL pin. If the CL pinis open, the current limit will be set to its maximum valueTSSR Set Current * Min CurrentMax Current * Min Current1.07 ms 300 mA * 57 mA512 mA * 57 mAT SS ³(eq. 2)2 msPWM SignalCOMP Voltage4.2 V3.5Ramp3.0 VSet LimitCurrent Limit57 mAInductor CurrentCorrectionTimeSoft Start TimeFigure 36. Soft Start TimeThe compensation of the converter must be manipulatedto minimize the overshoot of the output voltage duringstartup, details are in the compensation section.OV EnableOVComparatorVINLine Under and Over Voltage DetectorsThe NCP1032 incorporates Vin input line under voltage(UV) and over voltage (OV) shutdown circuits. If theUV/OV pin is set below 1.0 V or above 2.4 V thresholds thepower switch will stop switching and the part will use DSSuntil the problem is corrected. The comparators incorporatetypical voltage hysteresis of 70 mV (UV) and 158 mV (OV)to prevent noise from inadvertently triggering the shutdowncircuit. The UV/OV sense pin can be biased using anexternal resistor divider from the input line as shown inFigure 37. The UV/OV pin should be bypassed using a 1 nFcapacitor to prevent triggering the UV/OV circuit duringnormal switching operation.CUV1 nFR32.4 VR41VFaultLogicUVComparatorFigure 37. UV/OV Resistor Dividerfrom the Input LineThe resistive network impedance must not be too high tokeep good voltage accuracy and not too low to minimizepower losses. A 200 kW to 1.2 MW range is recommendedfor the high side resistor R3. If the designer wanted to set theundervoltage threshold to 32 V, the resistor divider should bedesigned according to the following equation:R4 V UV R3³V IN UV * V UV34.49 kW www.onsemi.com131.0671 MW32 V * 1.067(eq. 3)[ 34.0 kW (R96 Value)
NCP1032Oscillator, Voltage Feed Forward, and Sync CapabilityThe OV threshold monitored at the UV/OV pin is 2.41times higher than the UV threshold, leading to an OVthreshold of 73.3 V for the calculated R96 value. Designerscan quickly set the OV/UV thresholds by referencingFigure 38.The oscillator is optimized for operation up to 1 MHz andits frequency is set by the external timing capacitor (CT)connected to the CT pin. The oscillator has two modes ofoperation: free running and synchronized (sync). While infree running mode, an internal current source sequentiallycharges and discharges CT generating a voltage rampbetween 3.0 V and 3.5 V. Under normal operatingconditions, the charge (ICT C) and discharge (ICT D)currents are typically 172 mA and 515 mA, respectively. Thecharge/discharge current ratio of 1:3 discharges CT in 25%of the total period. The power switch is disabled while CT isdischarging, guaranteeing a maximum duty cycle of 75% asshown in Figure 39.120110INPUT VOLTAGE (V)100Overvoltage Threshold9080706050Undervoltage Threshold40COMP302010CT Ramp150200250300350400450500Power SwitchEnabledR3 (kW)Figure 38. UV/OV Resistor Divider Thresholdswith R4 Set to 10 kCT ChargeSignalThe UV/OV pin can also be used to implement a remoteenable/disable function. If an external transistor pulls theUV/OV pin below 1.0 V (or above 2.4 V) the converter willbe disabled and no switching is allowed. A device version isavailable without the OV protection feature, see the orderinginformation section.Max DutyCycle75%25%Figure 39. Auxiliary Winding Operation withOutput Overload Timing DiagramThe oscillator frequency should be set no more than 25%below the target sync frequency to maintain an adequatevoltage ramp and provide good noise immunity. A possiblecircuit to synchronize the oscillator is shown in Figure 40.Error AmplifierThe internal error amplifier (EA) regulates the outputvoltage of the bias supply. The scaled signal is fed into thefeedback pin (VFB) which is the inverting input of the erroramplifier. It compares a scaled voltage signal to an internaltrimmed 2.5 V reference connected to its non invertinginput.The output of the error amplifier is internally connectedto a PWM comparator and also available externally throughthe COMP pin for frequency compensation. To insurenormal operation, the EA compensation should be selectedsuch that the EA frequency response crosses 0 dB below80 kHz.The error amplifier feedback bias current is less than200 nA over the operating range. The output source and sinkcurrents are typically 95 mA and 700 mA, respectively.Under load transient conditions, COMP may need tomove from the bottom to the top of the CT ramp. A largecurrent is required to complete the COMP swing if smallresistors or large capacitors are used to implement thecompensation network. In which case, the COMP swing willbe limited by the EA source current. Optimum transientresponses are obtained if the compensation componentsallow the COMP pin to swing across its operating range in1 cycle.CTCTR1C1R2Figure 40. External FrequencySynchronization Circuitwww.onsemi.com142
NCP1032Voltage feed forward can be implemented by connectinga resistor from the input voltage to the CT pin. RFF suppliesa current that allows the input voltage to modify themaximum duty cycle rather than the standard 75%maximum. If the designer wanted to implement a fixedlower duty cycle, a resistor can be tied to a fixed voltagesource such as VAUX or a voltage reference. If voltage feedforward is used, the frequency can shift dramaticallydepending on the value of the resistor.The PWM comparator and latch propagation delay areless than 200 ns. If the system is designed to operate with aminimum on time less than 200 ns (no or light load), theconverter will skip pulses. Skipping pulses is usually not aproblem, unless operating at a frequency close to the audiblerange. Skipping pulses is more likely when operating at highfrequencies during high input voltage and minimum loadconditions.A 2 kW series resistor is included for ESD protectionbetween the internal EA output and the COMP pin. Undernormal operation, a 220 mV offset is observed between theCT ramp and the COMP crossing points. The series resistordoes not interact with the error amplifier transfer function.VINIFFCin2.2 mFVDRAINRFFProgrammable Current LimitThe power switch circuit incorporates SENSEFET technology to monitor the drain current. A sense voltage isgenerated by driving a sense element, RSENSE, with a currentproportional to the drain current. The sense voltage iscompared to an externally programmable reference voltageon the non inverting input of the current limit comparator.If the sense voltage exceeds the setup reference level, thecomparator resets the PWM latch and the switching cycle isterminated. The reference level threshold is programmableby a resistor (RCL) connected to the CL pin shown inFigure 42.By limiting the peak current to the needs of theapplication, the transformer sizing can be scaledappropriately to the specific requirements which allows thePCB footprint to be minimized. The NCP1032 maximumdrain current limit thresholds are 512 mA.Please refer to Figure 30 for ILIM vs. RCL relationship.Z14VGNDCTNCP1032CCTFeed Forward VoltageCT PIN VoltageOnOffTime75%OnOffTime66%OnOffTime me38%OnOffTime29%OffTime21%OnFigure 41. Voltage Feed ForwardR VFF VIN MIN * RampI CT D * D MAX320 kW ǒICT C ) ICT DǓ32 V * 3.25 V517 mA * 62%³(eq. 4)3.2 mAǒ172 mA ) 517 mAǓCurrent LimitComparator Fault Logic PWM Comparator and LatchThe Pulse Width Modulator (
Power Switch Enabled MOSFET is switching at 300 kHz 2.0 2.9 4.0 mA ICC2 Internal IC Consumption Power Switch Disabled No Fault condition, VFB 2.7 V 2.0 2.5 mA ICC3 Internal IC Consumption Power Switch Disabled Fault condition, VFB 2.7 V, VUV/OV 1.0 V 0.75 1.5 mA POWER SWITCH CIRCUIT RDSON Powe
Fan speed response to PWM control signal The fan‘s speed scales broadly linear with the duty-cycle of the PWM signal between maximum speed at 100% PWM and the specified minimum speed at 20% PWM (see www.noctua.at for individual fan specifications): For example, the NF-A12x25 PWM has a maximum speed of 2000r
,minimum ripple current PWM, Space vector PWM (SVM),Random PWM, hysteresis band current control PWM, Sinusoidal PWM with instantaneous current control etc.PWM feed forward or feedback methods, carrier or non carrier based control methods etc[1-3]. In [8] digital simulation of sinusoidal pulse width modulation presented, at rated
The PWM input wire (orange) and the feedback wire (white) for each servo will be attached to the Arduino pins as follows: Servo One - PWM - Digital 8, Feedback - Analog 1 Servo Two - PWM - Digital 9, Feedback - Analog 2 Servo Three - PWM - Digital 10, Feedback - Analog 3 Servo Four - PWM - Digital 11,
sinusoidal PWM and space Vector PWM. With the development of DSPs, space-vector modulation (SVM) has become one of the most important PWM methods for three-phase voltage source inverters. In this technique, Space-vector concept is used to compute the duty cycle of the switches. It is simply the digital implementation of PWM modulators.
The buck converters support 100% duty cycle operation to extend battery life. If the PWM pin is held low, the buck converters automatically transition from Burst Mode operation to PWM mode at high loads. With the PWM pin held high, the buck converters remain in low noise, 1.1MHz PWM mode. The buc
DSP TI 240LF with PWM outputs. DSP TI 240LF. With PWM outputs. DSP TI 240LF. With PWM outputs. DSP TI 240LF. With PWM outputs. WHEEL/Motor. WHEEL/Motor. WHEEL/Motor. WHEEL/Motor. Central 32 bit Micro-Controller. With GPS. CAN network. CAN Port. CAN Port. CAN Port. CAN Port. Self Guided Ve
Figure 2: Schematic of the digital current to PWM converter B. Analog Current to PWM Converter: The analog current to PWM converter in Fig. 3 consists of a capacitive TIA, a comparator, and digital logics. It is also operated by a clock. When the clock is low, the conversion operation is performed and when th
A Liteon Semiconductor Company - 1 - V2.1 OB2268 OB2269 Current Mode PWM Controller GENERAL DESCRIPTION OB2268/9 is a highly integrated current mode PWM control IC optimized for high performance, low
