Rev. 1.10 1 April 18, 2014 Rev. 1.00 PB April 18, 2014

HT7465Step-Down DC to DC Converter

Feature• Inputvoltagerange:4.75Vto24V• Variableoutputvoltagerange:0.92Vto20V• 2Aoutputcurrent• Efficiencyupto92%• Fixed380kHzoperatingfrequency• 20mAshutdowncurrent• InternalpowerMOSFETswitch• StableoperationusinglowESRceramiccapacitors• Overtemperatureprotection• Cycle-by-cycleovercurrentprotection• Undervoltagelockoutprotection• 8-pinSOPpackage

Applications• Batterychargers• Distributedpowersystems• LEDdriver• DSLmodems• Linearregulatorprepowerprocessing• Set-Top-Boxes,DVDplayers,LCDdisplays

General DescriptionTheHT7465isa2Ahighefficiencystep-downDC-DCconverterwhichincludesafullyintegratedMOSpower transistor.Thedeviceuses a current-modecontroloperatingmethodologyandcanoperateoverawideinputvoltagerangeof4.75Vto24Vforwhichitcanprovideastableadjustableoutputvoltage.

Thedevice includesover temperatureprotection,overcurrentprotectionandundervoltage lockoutprotection,featureswhichcombinetopreventdevicedamageduetooverloadconditions.In itsshutdownmode the regulatordrawsamere20uAof supplycurrent.

Thedevice isavailable in8-pinSOPpackage typeandprovidesaverycompactsystemsolutionwithaminimumofexternalcomponents.

Application Circuits

B230A

VIN

EN

GND COMP

HT7465

BS

SW

FB

22uF

10 F

L

10nF

R2

R1

VIN

VOUT

2

21

RRRVV FBOUT

4.75~24V

C4

C1C2

R3

C6C5

10/15 H

Efficiency vs Output Current

Rev. 1.10 2 April 18, 2014

HT7465

Block Diagram

RegulatorUnder-voltage

lockout

EN NC

Amplifier CurrentSense

ControlLogic

Current Sense

Soft-Start

PWM Comparator

OSC240/380kHz

ErrorAmplifier

0.92V

SCP

COMPFB

VIN

BS

SW

5V

GND

+ -

+

-

+

-

Pin Assignment

1234

8765

BSVINSW

GND

NCENCOMPFB

HT74658 SOP-A

(Exposed Pad)

PAD(GND)

Rev. 1.10 3 April 18, 2014

HT7465

Absolute Maximum RatingsMaximumInputSupplyVoltage............................26VSwitchNodeVoltage..............................................26VFeedbackVoltage.....................................................6V

ENVoltage...............................................................6VCompVoltage...........................................................6VMaximumJunctionTemperature....................... 150°C

Pin DescriptionPin No. Pin Name Description

1 BSInternal Power NMOS Gate Drive Boost Input.A 10nF or greater value capacitor should be connected from SW to BS for additional Power NMOS gate driving purposes.

2 VINPower supply input.The input supply pin for the device, VIN, is connected to a supply voltage between 4.75V to 24V.

3 SW Power switching output.The internal power MOS drain is connected to the inductor diode and VIN.

4 GND Ground.Device ground voltage reference.

5 FBFeedback pin.The feedback pin is connected to an external resistor divider to measure the output voltage.

6 COMP

Error Amplifier Output.Used for compensation of the regulation control loop. Connect a series RC network from COMP to GND to compensate the regulation control loop and the COMP pin value is 0.92V.

7 ENEnable Input and dimming control.This pin is set high to turn on the regulator and low to turn it off. The pin should be left unconnected if not used.

8 NC Not used

Exposed Pad GND Ground.Device ground voltage reference.

Note:Thesearestressratingsonly.Stressesexceedingtherangespecifiedunder“AbsoluteMaximumRatings”maycausesubstantialdamagetothedevice.Functionaloperationofthisdeviceatotherconditionsbeyondthoselistedin thespecificationisnot impliedandprolongedexposuretoextremeconditionsmayaffectdevicereliability.

Recommended Operating ConditionsInputSupplyVoltage................................4.75V~24V AmbientTemperatureRange............... -40°C~+85°C

Rev. 1.10 4 April 18, 2014

HT7465

Electrical CharacteristicsVIN=12V,Ta=25°C,unlessotherwisespecifiedrefertocircuitofFigure1.( note 1)

Symbol Parameter Test Condition Min. Typ. Max. Unit

VFB Feedback Voltage 4.75V ≤ VIN ≤ 24V 0.892 0.920 0.948 V

VUVLO Under Voltage Lockout Threshold — — 4.1 — V

— Under Voltage Lockout Threshold Hysteresis — — 200 — mV

IQ Quiescent Current VFB=1.2V, VEN=High — 1.1 1.3 mA

ISS Shutdown Supply Current VEN=0V — 20 30 mA

FOS Oscillator Frequency — — 380 — kHz

— Short Circuit Frequency VFB=0V — 240 — kHz

DMAX Maximum Duty Cycle VFB=0.6V — 90 — %

ISW Switch Leakage VEN=0V, VSW=0V — 0 10 mA

RDS Switch On Resistance (note 2) IOUT=2A — 0.18 — W

ILIMIT Current Limit — — 3.4 — A

— Error Amplifier Voltage Gain (note 2) — — 70 — dB

— Error Amplifier Trans-conductance (note 2) — — 800 — mA/V

VEN Enable Threshold 4.75V ≤ VIN ≤ 24V 0.7 1.0 1.3 V

TJ Thermal Shutdown — — 150 — °C

Note:1.Specificationsareproduction testedatTa=roomtemperature.Specificationsover the-40°C to85°Coperating temperaturerangeareassuredbydesign,characterizationandcorrelationwithStatisticalQualityControls(SQC).

2.Thetestspecificationsbydesigner.

Rev. 1.10 5 April 18, 2014

HT7465

Functional Description

Setting the Output VoltageTheHT7465 is a step down switchingDC/DCconverterdevice.Thedeviceswitchingoutput,SW,isconnectedtoastandardconverterLCfiltercircuitforbuckconversion.Theoutputcurrent issensedusinganexternalvoltagedividernetworkconnectedtotheloadoutputvoltageandground,andthesensevoltagefeedbacktothedeviceontheFBpin.Bycomparingthis sense voltagewith an internally generated0.92voltage reference, suitable regulationcanbeimplementedtoachievetherequiredoutputvoltage.By selecting suitable values of external voltagedivider resistors, thedesiredoutputvoltagecanbeadjustedtotherequiredlevel.Theoutputvoltagecanbecalculatedusingthefollowingformula:

VOUT=x0.92R1+R2R2

whereR2istheresistordividerlowerresistorandR1istheupperresistor.

Compensation ComponentsCare must be taken when selecting externalcomponents.TheCOMPpin is the output of theerroramplifierandmustbeproperlyconnectedtoanexternalRCnetworktoensureregulatorloopstability.Thevaluesof thecompensationcomponentsgiveninTable1yieldastablecontrol loopfor theoutputvoltageandcapacitorgiven.

Table1CompensationValues forTypicalOutputVoltage/CapacitorCombinations.

VOUT L R3 C4 C6 C5

2.5 10/15mH 9.1K 2.2n 22mF Ceramic —

3.3 10/15mH 10K 3.9n 22mF Ceramic —

5.0 10/15mH 18K 1.5n 22mF Ceramic —

Current Limit ProtectionThedevicehas a cycle-by-cycle current limit toprotect the internalpowerMOSFET.If the inductorcurrent reaches thecurrent limit thresholdof3.4A,theMOSFEToscillatorfrequencywillbetransformedfrom380kHztoashortcircuitfrequencyof240kHzandtheoutputcurrentwillremainatitscurrentlimitvalue.

Over — Temperature ProtectionA thermal shutdown function is implemented topreventdamagesdue toexcessiveheatandpowerdissipation.Typicallythethermalshutdownthresholdtemperatureis150°C.Whenthethermalshutdownis

triggeredthedevicestopsswitchingandwillrequireapoweron inputvoltage signal,before resumingswitchingoperation.

Application Information

InductorTheinductorisrequiredtosupplyaconstantcurrenttotheoutputloadwhilebeingdrivenbytheswitchedinputvoltage.Thechoiceof inductoraffectssteadystate operation aswell as transient behavior andloopstability.Thereare three importantelectricalparameterswhich need to be consideredwhenchoosinganinductor:

• Theinductorvalue• DCR-copperwireresistance• ThesaturationcurrentInductor choice is especially important as it isimportant toensure the inductordoesnot saturateunderitspeakcurrentconditions.AlsoensurethattheinductorhasalowDCRtominimisepowerlosses.

Input/Output CapacitorInput CapacitorBecausetheVINpinisconnectedtotheinternalpowerMOSFET,whenthepowerMOSFETisswitchingandtheinputcurrentisdiscontinuous,thereforeaninputcapacitorC1 is required to supply theACcurrentto the step-downconverterwhilemaintaining theDCinputvoltage.A lowESRceramiccapacitor isrequiredtokeepnoisetoaminimum.

Output CapacitorTheoutputcapacitor isrequiredtomaintaintheDCoutput voltage.Ceramicor lowESRelectrolyticcapacitors is the rule to choice of external loadcapacitorisalsocriticalandlowESRvaluecapacitorsmustbeusedtoensurestability.Thiscapacitormustbeconnectedveryclose to the inductor,withshorttracesforgoodnoiseperformance.

Schottky DiodeTheoutputdiodeconductswhenthe internalpowerMOSFETisswitchedoff.Therearethreeimportantelectricalparameters toconsiderwhenchoosingthediode:

• Thediodemaximumreversevoltagevaluemustgreaterthanthemaximuminputvoltage

• Shortrecoverytime--useSchottkydiode• Diodecurrentratingshouldbegreaterthanthemaximumloadcurrent

Rev. 1.10 6 April 18, 2014

HT7465

Layout ConsiderationsCircuitboardlayoutisaveryimportantconsiderationfor switching regulators if they are to functionproperly.Poorcircuit layoutmay result in relatednoise problems. In order tominimise EMI andswitchingnoise,followtheguidelinesbelow:

• Alltracksshouldbeaswideaspossible.• Theinputandoutputcapacitors,C1(C8)andC6(C7),shouldbeplacedclosetotheVIN,VOUTandGNDpins(C1andC8isparallel;C6andC7isparallel).

• TheSchottkydiodeDandinductorLmustbeplacedclosectotheSWpin.

• Feedbackresistor,R1(R1-1)andR2,mustbeplacedclosetotheFBandGNDpins(R1andR1-1isseries).

• AfullgroundplaneisalwayshelpfulforbetterEMIperformance.

A recommended PCB layout with componentlocationsisshownbelow.

Top Layer

Bottom Layer

Rev. 1.10 7 April 18, 2014

HT7465

Package Information

Notethat thepackageinformationprovidedhereisforconsultationpurposesonly.Asthis informationmaybeupdatedatregularintervalsusersareremindedtoconsulttheHoltekwebsiteforthelatestversionofthePackage/CartonInformation.

Additionalsupplementaryinformationwithregardtopackagingislistedbelow.Clickontherelevantsectiontobetransferredtotherelevantwebsitepage.

• FurtherPackageInformation(includeOutlineDimensions,ProductTapeandReelSpecifications)

• PackingMeterialsInformation

• Cartoninformation

Rev. 1.10 8 April 18, 2014

HT7465

8-pin SOP_EP (150mil) Outline Dimensions for Thermally Enhanced Variations Only (Exposed Pad)

�

�

� � ��

��

�

�� �

�

�

�

SymbolDimensions in inch

Min. Nom. Max.A ― 0.236 BSC ―B ― 0.154 BSC ―C 0.012 ― 0.020C' ― 0.193 BSC ―D ― ― 0.069

D1 0.059 ― ―E ― 0.050 BSC ―

E2 0.039 ― ―F 0.004 ― 0.010G 0.016 ― 0.050H 0.004 ― 0.010α 0° ― 8°

SymbolDimensions in mm

Min. Nom. Max.A ― 6.00 BSC ―B ― 3.90 BSC ―C 0.31 ― 0.51C' ― 4.90 BSC ―D ― ― 1.75

D1 1.50 ― ―E ― 1.27 BSC ―

E2 1.00 ― ―F 0.10 ― 0.25G 0.40 ― 1.27H 0.10 ― 0.25α 0° ― 8°

Rev. 1.10 9 April 18, 2014

HT7465

Copyright© 2014 by HOLTEK SEMICONDUCTOR INC.

The information appearing in this Data Sheet is believed to be accurate at the time of publication. However, Holtek assumes no responsibility arising from the use of the specifications described. The applications mentioned herein are used solely for the purpose of illustration and Holtek makes no warranty or representation that such applications will be suitable without further modification, nor recommends the use of its products for application that may present a risk to human life due to malfunction or otherwise. Holtek's products are not authorized for use as critical components in life support devices or systems. Holtek reserves the right to alter its products without prior notification. For the most up-to-date information, please visit our web site at http://www.holtek.com.