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1、MP1495High Efficiency 3A, 16V, 500kHz Synchronous Step Down ConverterThe Future of Analog IC TechnologyMPSDESCRIPTIONAND PROPRIETARY INFORMATION - MTC INTERNAL USE ONLYFEATURESThe MP1495 is a high-frequency, synchronous, rectified, step-down, switch-mode converter with built-in power MOSFETs. It off

2、ers a very compact solution to achieve a 3A continuous output current with excellent load and line regulation over a wide input supply range. The MP1495 has synchronous mode operation for higher efficiency over the output current load range.Current-mode operation provides fast transient response and

3、 eases loop stabilization.··Wide 4.5V-to-16V Operating Input Range 80m/30m Low RDS(ON) Internal Power MOSFETsHigh-Efficiency Synchronous Mode OperationFixed 500kHz Switching Frequency Synchronizes to a 200kHz to 2MHz External ClockAAM Power-Save Mode Internal Soft-Start···&#

4、183;·····OCPand HiccupThermal ShutdownOutput Adjustable from 0.8VAvailable in an 8-pin TSOT-23 packageFullfeatures include over-current and thermal shut down.MP1495 requires a minimal number of ily-available standard external components,TheAPPLICATIONSandisavailableinaspace-

5、saving TSOT23 package.8-pin····Notebook Systems and I/O Power Digital Set-Top BoxesFlat-Panel Television and Monitors Distributed Power SystemsAll MPS parts are lead-and adhere to the RoHS directive. For MPS greenstatus, please visit MPS website under Quality Assurance. “MPS” and

6、 “The Future of Analog IC Technology” are Registered Trademarks of Monolithic Power Systems, Inc.TYPICAL APPLICATIONEfficiency vs. Load CurrentVIN=12V, VOUT=3.3V, AAM=0.5VR4 104.5V-16V52VININBST100C1 22C4 MP1495EN/SYNC9533.3V/2A6SWL1 90EN/C2 47SYNCR1 40.2k7VIN=12VR985VCCFB 833kC3 0.1R38090.9k1R213kA

7、AMGND75R5410k700.010.1110LOAD CURRENT(A)1MP1495 Rev. 1.03 9/19/2012MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited.20121121181713243© 2012 MPS.VIN=16VVIN=5VMP1495 SYNCHRONOUS STEP-DOWN CONVERTERMPSAND PROPRIETARY INFORMATION - MTC INTERNAL USE ON

8、LYORDERING INFORMATIONFor Tape & Reel, add suffix Z (e.g. MP1495DJZ);For RoHS, compliant packaging, add suffix LF (e.g. MP1495DJLFZ).PACKAGE REFERENCEUM RATINGS (1)(5)ABSOLUTEThermalJAJCVIN.-0.3V to 17VTSOT-23-8. 100 . 55. °C/WVSW.-0.3V (-5V for <10ns) to 17V (19V for <10ns)Notes:1)2)

9、Exceeding these ratings may damage the device.VBSVSW+6VAll Other Pins0.3V to 6V (2)About thes of EN pins ABS MAX rating, please refer toPage 9, Enable/SYNC control section.3)Theum allowable power dissipation is a function of theContinuous Power Dissipation (T = +25°C) (3)um junction temperature

10、 TJ (MAX), the junction-to-Aambient thermalJA, and the ambient temperature. 1.25WTA. Theum allowable continuous power dissipation atJunction Temperature150°Cany ambient temperature is calculated by PD (MAX) = (TJLead Temperature260°CStorage Temperature. -65°C to 150°CRecommended

11、Operating Conditions (4)Supply Voltage VINV to 16V Output Voltage VOUTV to VIN-3VOperating Junction Temp. (TJ). -40°C to +125°C(MAX)-TA)/JA. Exceeding theum allowable powerdissipation will cause excessive die temperature, and theregulator will go into thermal shutdown. Internal thermal shu

12、tdown circuitry protects the device from permanent damage.The device is not guaranteed to function outside of its operating conditions.Measured on JESD51-7, 4-layer PCB.4)5)2MP1495 Rev. 1.03 9/19/2012MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited.201

13、21121181713243© 2012 MPS.Part Number*PackageTop MarkingMP1495DJTSOT-23-8ACSMP1495 SYNCHRONOUS STEP-DOWN CONVERTERMPSAND PROPRIETARY INFORMATION - MTC INTERNAL USE ONLY(6)ELECTRICAL CHARACTERISTICSVIN = 12V, TA = 25°C, unless otherwise noted.Notes:6) Guaranteed by design.7) Not tested in pr

14、oduction and guaranteed by over temperature correlation.3MP1495 Rev. 1.03 9/19/2012MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited.20121121181713243© 2012 MPS.ParameterSymbolConditionMinTypMaxUnitsSupply Current (Shutdown)IINVEN = 0V1ASupply Curr

15、ent (Quiescent)IqVEN = 2V, VFB = 1V, AAM=0.5V0.51mAHS Switch-ONHSRDS-ONVBST-SW=5V80mLS Switch-ONLSRDS-ONVCC =5V30mSwitch LeakageSWLKGVEN = 0V, VSW =12V1ACurrent Limit (6)ILIMITUnder 40% Duty Cycle4.25AOscillator FrequencyfSWVFB=0.75V440500580kHzFold-Back FrequencyfFBVFB<400mV0.25fSWum Duty CycleD

16、MAXVFB=700mV9095%Minimum ON Time(6)tON_MIN60nsSync Frequency RangefSYNC0.22MHzFeedback VoltageVFBTA =25°C791807823mV-40°C<TA<85°C (7)787807827Feedback CurrentIFBVFB=820mV1050nAEN Rising ThresholdVEN_RISINGVEN Falling ThresholdVEN_FALLINGVEN Input CurrentIENVEN

17、=2V2AVEN=00AEN Turn-Off DelayENtd-off8sVIN Under-Voltage Lockout Threshold-RisingINUVVthVVIN Under-Voltage Lockout Threshold-HysteresisINUVHYS650mVVCC RegulatorVCC5VVCC Load RegulationICC=5mA3%Soft-Start PeriodtSS1.5msThermal Shutdown (6)150°CThermal Hysteresis (6)20°CMP1495 SYNCH

18、RONOUS STEP-DOWN CONVERTERMPSAND PROPRIETARY INFORMATION - MTC INTERNAL USE ONLYTYPICAL PERFORMANCE CHARACTERISTICSPerformance waveforms are tested on the evaluation board of the Design Example section. VIN = 12V, VOUT = 3.3V, AAM=0.5V, TA = 25°C, unless otherwise noted.Load RegulationVIN=4.5V-

19、16V, IOUT=0-2A00.050.00-0.05-0.10-0.151001009595V =12VINVIN=5VVIN=12V9090VIN=5VVIN=16V8585VIN=16VVIN=12VVIN=4.5V8080VIN=16V75757070-0.2000.511.522.5300.511.522.5300.511.522.53LOAD CURRENT(A)LOAD CURRENT(A)OUTPUT CURRENT(A)Line RegulationVIN=5-16VPeak Current vs. Duty CycleDisabled Supply

20、Current vs. Input VoltageVIN=6-16V, IOUT=0A1.00.20.0-0.2-0.4-0.6-0.8-1.05.950403020100IOUT=0A5.55.1I=1.5AOUT4.74.3IOUT=3A-10-203.93.5-30468 1012141610203040506070468 10 12 14 1INPUT VOLTAGE(V)INPUT VOLTAGE(V)Enabled Supply Current vs. Input VoltageCase Temperature Rise vs. Output CurrentVIN

21、=6-16V, IOUT=0A540IOUT=0-3A3053553052552051525201510500468 10 1214 16 180.511.522.53INPUT VOLTAGE(V)OUTPUT CURRENT(A)4MP1495 Rev. 1.03 9/19/2012MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited.20121121181713243© 2012 MPS.PEAK CURRENT(A)INPUT CURRE

22、NT(nA)MP1495 SYNCHRONOUS STEP-DOWN CONVERTERMPSAND PROPRIETARY INFORMATION - MTC INTERNAL USE ONLYTYPICAL PERFORMANCE CHARACTERISTICS (continued)Performance waveforms are tested on the evaluation board of the Design Example section. VIN = 12V, VOUT = 3.3V, AAM=0.5V, TA = 25°C, unless otherwise

23、noted.Start up through Input VoltageIOUT=0AShutdown through Input VoltageIOUT=0AVEN5V/div.VEN5V/div.VOUT/AC100mV/div.VOUT2V/div.VOUT2V/div.VSW5V/div. I-inductor 2A/div.VSW5V/div. I-inductor 2A/div.IOUT1A/div.Start up through Input VoltageIOUT=3AShutdown through Input VoltageIOUT=3AStartup through En

24、ableIOUT=0AVEN5V/div.VEN5V/div.VOUT2V/div.VEN5V/div.VOUT2V/div.VOUT2V/div.VSW5V/div.VSW5V/div.I-inductor 2A/div.VSW5V/div.I-inductor 2A/div.I-inductor2A/div.Shuthdown through EnableIOUT=0AStartup through EnableIOUT=3AShutdown through EnableIOUT=3AVEN5V/div.VEN5V/div.VEN5V/div.VOUT2V/div.VOUT2V/div.V

25、OUT2V/div.VSW5V/div.VSW5V/div.VSW5V/div.I-inductor 2A/div.II-inductor2A/div.-inductor2A/div.5MP1495 Rev. 1.03 9/19/2012MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited.20121121181713243© 2012 MPS.MP1495 SYNCHRONOUS STEP-DOWN CONVERTERMPSAND PROPRI

26、ETARY INFORMATION - MTC INTERNAL USE ONLYTYPICAL PERFORMANCE CHARACTERISTICS (continued)Performance waveforms are tested on the evaluation board of the Design Example section. VIN = 12V, VOUT = 3.3V, AAM=0.5V, TA = 25°C, unless otherwise noted.Input / Output RippleIOUT=3AShort Circuit EntryIOUT

27、=0AShort Circuit RecoveryIOUT=0AVIN/AC200mV/div.VOUT2V/div.VOUT2V/div.VOUT/AC20mV/div.VSW5V/div.VSW5V/div.VSW10V/div.I-inductor 5A/div.I-inductor 5A/div.I-inductor 2A/div.6MP1495 Rev. 1.03 9/19/2012MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited.20121

28、121181713243© 2012 MPS.MP1495 SYNCHRONOUS STEP-DOWN CONVERTERMPSAND PROPRIETARY INFORMATION - MTC INTERNAL USE ONLYPIN FUNCTIONS7MP1495 Rev. 1.03 9/19/2012MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited.20121121181713243© 2012 MPS.Package Pi

29、n #NameDescription1AAMAdvanced Asynchronous Modulation. Connect the tap of 2 resistor dividers to force the MP1495 into non-synchronous mode under light loads. Drive AAM pin high (VCC) to force the MP1495 into CCM.2INSupply Voltage. The MP1495 operates from a 4.5V to 16V input rail. Requires C1 to d

30、ecouple the input rail. Connect using a wide PCB trace.3SWSwitch Output. Connect using a wide PCB trace.4GNDSystem Ground. This pin is the reference ground of the regulated output voltage, and PCB layout requires special care. For best results, connect to GND with copper traces and vias.5BSTBootstra

31、p. Requires a capacitor connected between SW and BST pins to form a floating supply across the high-side switch driver. A 10 resistor placed between SW and BST cap is strongly recommended to reduce SW spike voltage.6EN/SYNCEnable/Synchronize. EN high to enable the MP1495. Apply an external clock to

32、the EN pin to change the switching frequency.7VCCBias Supply. Decouple with 0.1F-to-0.22F capacitor. Select a capacitor that does not exceed 0.22F. VCC capacitor should be putly to Vin and GND pin.8FBFeedback. Connect to the tap of an external resistor divider from the output to GND, to set the outp

33、ut voltage. The frequency fold-back comparator lowers the oscillator frequency when the FB voltage is below 400mV to prevent current limit runaway during a short-circuit fault condition.MP1495 SYNCHRONOUS STEP-DOWN CONVERTERMPSAND PROPRIETARY INFORMATION - MTC INTERNAL USE ONLYBLOCK DIAGRAMFigure 1:

34、 Functional Block Diagram8MP1495 Rev. 1.03 9/19/2012MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited.20121121181713243© 2012 MPS.MP1495 SYNCHRONOUS STEP-DOWN CONVERTERMPSAND PROPRIETARY INFORMATION - MTC INTERNAL USE ONLYOPERATIONThe MP1495 is a h

35、igh-frequency, synchronous, rectified, step-down, switch-mode converter with built-in power MOSFETs. It offers a very compact solution to achieve 3A continuous output current with excellent load and line regulation over a wide input supply range.The MP1495 operates in a fixed-frequency, peak-current

36、controlmodetoregulatethe output voltage. An internal clock initiates a cycle. The integrated high-side power MOSFET turns on and remains on until its current reaches the value set by the COMP voltage. When the power switch is off, it remains off until the next clock cycle starts. If the current in t

37、he power MOSFET does not reach the current value set by COMP withinFor example, with 12V connected to VIN, RPULLUP (12V 6.5V) ÷ 100µA = 55k.Connecting the EN pin is directly to a voltage source without any pullup resistor requires limiting voltage amplitude to 6V to prevent damage to the Z

38、ener diode.Figure 2: 6.5V-type Zener Diode Connect an external clock with a range of 200kHz to 2MHz 2ms after output voltage is set to synchronize the internal clock rising edge to the external clock rising edge. The pulse width of external clock signal should be less than 1.7s.Under-Voltage Lockout

39、Under-voltage lockout (UVLO) protects the chip from operating at an insufficient supply voltage. The MP1495 UVLO comparator monitors the output voltage of the internal regulator, VCC. The UVLO rising threshold is about 3.9V while its falling threshold is 3.25V.Internal Soft-StartThe soft-start preve

40、nts the converter output voltage from overshooting during startup. When the chip starts, the internal circuitry generates a soft-start voltage (SS) that ramps up from 0V to 1.2V. When SS is lower than REF, SS overrides REF so the error amplifier uses SS as the reference. When SS exceeds REF, the err

41、or amplifier uses REF as the reference. The SS time is internally set to 1.5ms.95% of oneperiod, the power MOSFETwill be forced to turn off.Internal RegulatorThe 5V internal regulatorpower most of theinternal circuitries. This regulator takes theVINinput and operates in the fullrange: WhenVINVIN exc

42、eeds 5.0V, the output of the regulator is in full regulation; when VIN falls below 5.0V, the output decreases and requires a 0.1µF decoupling ceramic capacitor.Error AmplifierThe error amplifier compares the FB pin voltage the internal 0.8V reference (REF) andoutputs a COMP voltagethis COMP vol

43、tage controls the power MOSFET current. Theoptimizedinternalcompensationnetworkminimizes the external component count and simplifies the control loop design.Enable/SYNC controlEN/Sync is a digital control pin that turns the regulator on and off: Drive EN high to turn on the regulator, drive it low t

44、o turn it off. An internal 1M resistor from EN/Sync to GND allows EN/Sync to be floated to shut down the chip.The EN pin is clamped internally using a 6.7V series Zener diode, as shown in Figure 2. Connect the EN input pin through a pullupOver-Currentand HiccupThe MP1495 has cycle-by-cycle over curr

45、ent limit for when the inductor current peak value exceeds the set current limit threshold. If the output voltage starts to drop until FB is below the Under-Voltage (UV) thresholdtypically 50% below the referencethe MP1495 enters hiccup mode to periodically restart the part.resistor to any voltage c

46、onnected to theVINpinthe pullup resistor limits the EN input current to less than 100µA.9MP1495 Rev. 1.03 9/19/2012MPS Proprietary Information. Patent Protected. Unauthorized Photocopy and Duplication Prohibited.20121121181713243© 2012 MPS.MP1495 SYNCHRONOUS STEP-DOWN CONVERTERMPSAND PROPR

47、IETARY INFORMATION - MTC INTERNAL USE ONLYThismode is especially useful whenthe output is dead-shorted to ground. Theaverage short-circuit current is greatly reduced to alleviate the thermal issue and to protect the regulator. The MP1495 exits the hiccup mode once the over-current condition is remov

48、ed.Thermal ShutdownThermal shutdown prevents the chip from operating at exceedingly high temperatures. When the silicon die temperature exceeds 150°C, it shuts down the whole chip. When the temperature drops below its lower threshold (typically 130°C) the chip is enabled again.Floating Dri

49、ver and Bootstrap ChargingAn external bootstrap capacitor powers the floating power MOSFET driver. This floatingdriver has its own UVLO rising threshold of 2.2V and, with a hysteresis of150mV. The bootstrap capacitor voltage isregulated internally by VIN through D1, M1, C4, L1 and C2 (Figure 3). If

50、(VIN-VSW) exceeds 5V, U1 regulates M1 to maintain a 5V BST voltage across C4. A 10 resistor placed between SW and BST cap is strongly recommended to reduce SW spike voltage.Figure 3: Internal Bootstrap Charging Circuit, Startup and ShutdownIf bothVINand EN exceed their appropriatethresholds, the chip starts: The reference block starts first, generating stable reference voltage and currents, and then the internal regulator is enabled. The regulator provides stable