18-Bit ADC with I2C Interface and Onboard …

1 2015 Microchip Technology 1HV9910 BFeatures Switch mode controller for single switch LED drivers Enhanced drop-in replacement to the HV9910 Open loop peak current controller Internal to 450V linear regulator Constant frequency or constant off-time operation Linear and PWM dimming capability Requires few external components for operationApplications DC/DC or AC/DC LED driver applications RGB backlighting LED driver Back lighting of flat panel displays General purpose constant current source Signage and decorative LED lighting ChargersDescriptionHV9910B is an open loop, current mode control, LEDdriver IC. This IC can be programmed to operate ineither a constant frequency or constant off-time includes an - 450V linear regulator which allows itto work from a wide range of input voltages without theneed for an external low voltage supply.

2 HV9910 Bincludes a PWM-dimming input that can accept anexternal control signal with a duty ratio of 0 - 100% anda frequency of up to a few kilohertz. It also includes a 0- 250mV linear dimming input which can be used for lin-ear dimming of the LED current. HV9910B is ideally suited for buck LED drivers. Sincethe HV9910B operates in open loop current mode con-trol, the controller achieves good output current regula-tion without the need for any loop compensation. PWMdimming response is limited only by the rate of rise andfall of the inductor current, enabling very fast rise andfall times. HV9910B requires only three external com-ponents, apart from the power stage, to produce a con-trolled LED current.

3 This makes HV9910B an idealsolution for low cost LED High-Brightness LED DriverHV9910 BDS20005344A-page 2 2015 Microchip Technology TypeTypical Application circuit 8-Lead SOIC16-Lead SOIC1234567816 15 14 13 12 11 10 9 87651234 VINCSGNDGATERTLDVDDPWMDVINNCNCCSGNDNCNCG ATENCNCRTLDVDDNCNCPWMDSee Table 2-1 for pin informationCDDRTRCSL1Q1D1 COCINHV9910 BVINGATEPWMDVDDLDCSRTGND 2015 Microchip Technology ELECTRICAL CHARACTERISTICSABSOLUTE MAXIMUM RATINGS VIN to to +470 VVDD to , LD, PWMD, GATE, RT to GND .. to (VDD + )Operating temperature ..-40 C to +125 CStorage temperature ..-65 C to +150 CContinuous power dissipation (TA = +25 C)8-lead SOIC.

4 630 mW16-lead SOIC ..1300 mWNote: Stresses above those listed under Absolute MaximumRatings may cause permanent damage to the device. This isa stress rating only and functional operation of the device atthose or any other conditions, above those indicated in theoperational listings of this specification, is not implied. Expo-sure to maximum rating conditions for extended periods mayaffect device SPECIFICATIONSTABLE 1-1:ELECTRICAL CHARACTERISTICS (SHEET 1 OF 2)1 SymbolParameterNoteMinTypMaxUnits ConditionsInputVINDCI nput DC supply voltage input voltageIINSDShut-down mode supply PWMD to GNDI nternal RegulatorVDDI nternally regulated = , IDD(ext) = 0, 500pF at GATE; RT = 226k , PWMD = VDD VDD, lineLine regulation of = - 450V, IDD(ext) = 0, 500pF at GATE; RT = 226k , PWMD = VDD VDD, loadLoad regulation of VDD-0-100mVIDD(ext) = 0 - , 500pF at GATE.

5 RT = 226k , PWMD = VDDUVLOVDD undervoltage lockout rising UVLOVDD undervoltage lockout hysteresis--500-mVVDD fallingIIN,MAXC urrent that the regulator can supply before IC goes into = Dimming VEN(lo)Pin PWMD input low = - 450 VVEN(hi)Pin PWMD input high = - 450 VRENPin PWMD pull-down resis-tance at PWMD-50100150k VPWMD = 4 2015 Microchip Technology Sense ComparatorVCS,THCurrent sense pull-in thresh-old voltage-225250275mV-40 C < TA < +85 C213250287TA < +125 CVOFFSETO ffset voltage for LD com-parator3-12-12mVTBLANKC urrent sense blanking interval-150215280ns0 < TA < +85 C, VLD = VDD, VCS = VCS,TH + 50mV after TBLANK-145215315-40 < TA < +125 C, VLD = VDD, VCS = VCS,TH + 50mV after TBLANKtDELAYD elay to output--80150nsVLD = VDD, VCS = VCS.

6 TH + 50mV after TBLANKO scillatorfOSCO scillator frequency-202530kHzRT = -80100120RT = 226k Gate DriverISOURCEGATE sourcing current-165--mAVGATE = 0V, VDD = sinking current-165--mAVGATE = VDD, VDD = output rise time--3050nsCGATE = 500pF, VDD = output fall time--3050nsCGATE = 500pF, VDD = are TA = 25 C, VIN = 15V unless otherwise limited by package-power dissipation limit; Whichever is over the full operating ambient temperature range of -40 C < TA < +125 design guidance onlyTABLE 1-1:ELECTRICAL CHARACTERISTICS (CONTINUED) (SHEET 2 OF 2)1 SymbolParameterNoteMinTypMaxUnits ConditionsTABLE 1-2:THERMAL RESISTANCEP ackage ja8-Lead SOIC101 C/W16-Lead SOIC83 C/W 2015 Microchip Technology PIN DESCRIPTIONThe locations of the pins are listed in Package 2-1:PIN DESCRIPTIONPin #FunctionDescription8-Lead SOIC 16-Lead SOIC11 VINI nput of an - 450V linear sense pin used to sense the FET current by means of an external sense resistor.

7 When this pin exceeds the lower of either the internal 250mV or the voltage at the LD pin, the GATE output goes return for all internal circuitry. This pin must be electrically connected to the ground of the power GATE driver for an external N-channel power dimming input of the IC. When this pin is pulled to GND, the GATE driver is turned off. When the pin is pulled high, the GATE driver operates supply for all internal must be bypassed with a low ESR capacitor to GND ( F).713 LDLinear dimming input and sets the current sense threshold as long as the voltage at the pin is less than 250mV (typ).814 RTSets the oscillator frequency. When a resistor is connected between RT and GND, the HV9910B operates in constant fre-quency mode.

8 When the resistor is connected between RT and GATE, the IC operates in constant off-time , 3, 6, 7, 10, 11, 15, 16 NCNo connectionHV9910 BDS20005344A-page 6 2015 Microchip Technology INFORMATIONHV9910B is optimized to drive buck LED drivers usingopen-loop, peak current mode control. This method ofcontrol enables fairly accurate LED current controlwithout the need for high side current sensing or thedesign of any closed loop controllers. The IC uses veryfew external components and enables both Linear andPWM-dimming of the LED current. A resistor connected to the RT pin programs the fre-quency of operation (or the off-time).

9 The oscillator pro-duces pulses at regular intervals. These pulses set theSR flip-flop in the HV9910B which causes the GATE driver to turn on. The same pulses also start the blank-ing timer, which inhibits the reset input of the SR flip-flop and prevent false turn-offs due to the turn-on the FET turns on, the current through the induc-tor starts ramping up. This current flows through theexternal sense resistor RCS and produces a ramp volt-age at the CS pin. The comparators are constantlycomparing the CS pin voltage to both the voltage at theLD pin and the internal 250mV. Once the blanking timeris complete, the output of these comparators is allowedto reset the flip-flop.

10 When the output of either one ofthe two comparators goes high, the flip flop is reset andthe GATE output goes low. The GATE goes low untilthe SR flip-flop is set by the oscillator. Assuming a 30%ripple in the inductor, the current sense resistor RCScan be set using:Constant frequency peak current mode control has aninherent disadvantage at duty cycles greater , the control scheme goes into subharmonic oscilla-tions. To prevent this, an artificial slope is typicallyadded to the current sense waveform. This slope com-pensation scheme will affect the accuracy of the LEDcurrent in the present form. However, a constant off-time peak current control scheme does not have thisproblem and can easily operate at duty cycles greaterthen This control scheme also gives inherent inputvoltage rejection, making the LED current almostinsensitive to input voltage variations.