18-Channel, Gamma Voltage Generator with Two …

1 FEATURESD18- channel Gamma CORRECTIOND2- channel programmable vcom :100mA IOUTD10-BIT RESOLUTIONDRAIL-TO-RAIL OUTPUTDLOW SUPPLY CURRENT: 900 A/chDSUPPLY Voltage : 7V to 18 VDDIGITAL SUPPLY: to , TWO- High-Speed ModeDHIGH ESD RATING:4kV HBM, 1kV CDM, 200V MMDDEMO BOARD AND SOFTWARE AVAILABLEREFH OUTREFHD igital( to )Analog(7V to 18V)REFLAOLDSCLSDAREFL OUTOUT 18 OUT 17 DAC RegistersControl IFOUT 1 OUT Output Channels plusTwo VCOMC hannelsBUF20800 DAC RegistersVCO M OUT1 VCO M OUT2 APPLICATIONSDREPLACES RESISTOR-BASED GAMMASOLUTIONSDTFT-LCD REFERENCE DRIVERSDDYNAMIC Gamma CONTROLDESCRIPTIONThe BUF20800 is a programmable Voltage referencegenerator designed for Gamma correction in TFT-LCDpanels. It provides 18 programmable outputs for gammacorrection and two channels for vcom adjustment, eachwith 10-bit programmability replaces the traditional, time-consuming process of changing resistor values to optimizethe various Gamma voltages and allows designers todetermine the correct Gamma voltages for a panel veryquickly.

2 Required changes can also be easily implementedwithout hardware BUF20800 uses TI s latest, small-geometry analogCMOS process, which makes it a very competitive choicefor full production, not just of each output occurs through an industry-standard, two-wire serial interface. Unlike existingprogrammable buffers, the BUF20800 offers a high-speedmode that allows clock speeds up to lower channel count, please contact your local salesor marketing BUF20800 is available in an HTSSOP-38 PowerPAD package. It is specified from 40 C to +85 RELATED PRODUCTSFEATURESPRODUCT18- channel programmable , Two vcom + OTP MemoryBUF2082012- channel programmable Buffer, 10-BitBUF12800 programmable VCOMBUF0190011-, 6-, 4- channel Gamma Correction Buffer, 18V SupplyBUFxx704 High-Speed vcom , 1 and 2 ChannelsSN10501 Complete LCD DC/DC SolutionTPS65100 BUF20800 SBOS329E JUNE 2005 REVISED DECEMBER 200718- channel Gamma Voltage Generator with Two programmable vcom Channels !

3 ! 2005 2007, Texas Instruments IncorporatedPlease be aware that an important notice concerning availability, standard warranty, and use in critical applications of Texas Instrumentssemiconductor products and disclaimers thereto appears at the end of this data is a registered trademark of Texas Instruments. All other trademarks are the property of their respective owners." #$%&%%SBOS329E JUNE 2005 REVISED DECEMBER integrated circuit can be damaged by ESD. Texas Instruments recommends that all integrated circuits be handled with appropriateprecautions. Failure to observe proper handling and installation procedures can cause damage can range from subtle performance degradation to complete device failure. Precision integrated circuits may be more susceptible todamage because very small parametric changes could cause the device not to meet its published MAXIMUM RATINGS(1)Supply Voltage , VS +19V.

4 Supply Voltage , VSD +6V.. Signal Input Terminals, SCL, SDA, AO, LD: Voltage to +6V.. Current 10mA.. Output Short Circuit(2) Continuous.. Operating Temperature 40 C to +95 C.. Storage Temperature 65 C to +150 C.. Junction Temperature+125 C.. ESD Rating:Human Body Model (HBM)4kV.. Charged-Device Model (CDM)1kV.. Machine Model (MM)200V.. (1)Stresses above these ratings may cause permanent damage. Exposure to absolute maximum conditions for extended periods may degradedevice reliability. These are stress ratings only, and functional operation of the device at these or any other conditions beyond those specified isnot supported.(2)Short-circuit to ground, one amplifier per INFORMATION(1)PRODUCTPACKAGE-LEADPACKAGE DESIGNATORPACKAGE MARKINGBUF20800 HTSSOP-38 DCPBUF20800(1)For the most current package and ordering information, see the Package Option Addendum at the end of this document, or see the TI web siteat " #$%&%%SBOS329E JUNE 2005 REVISED DECEMBER CHARACTERISTICS Boldface limits apply over the specified temperature range, TA = 40 C to +85 TA = +25 C, VS = 18V, VSD = 5V, RL = connected to ground, and CL = 200pF, unless otherwise noted.

5 BUF20800 PARAMETERCONDITIONSMINTYPMAXUNITANALOGG amma Output Swing HighOUT 1 9, Sourcing 10mA, VREFH = , Code 10 18, Sourcing 10mA, VREFH = , Code Output Swing LowOUT 1 9, Sinking 10mA, VREFL = , Code 10 18, Sinking 10mA, VREFL = , Code Buffer Output Swing HighVCOM, Sourcing 100mA, VREFH = Buffer Output Swing LowVCOM, Sinking 100mA, VREFL = Current(1)IOAll Channels, Code 512, Sinking/Sourcing4045mAREFH Input Range(2)4 VSVREFL Input Range(2)GNDVS 4 VIntegral NonlinearityINLNo Load, VREFH = 17V, VREFL = NonlinearityDNLNo Load, VREFH = 17V, VREFL = to Out DelaytD5 sOutput AccuracyNo Load, VREFH = 17V, VREFL = 1V 20 50mVOver Temperature 25mVInput Resistance at VREFH and VREFLRINH100M Load Regulation, All ReferencesREGVOUT = VS/2, IOUT = +5mA to 5mA , All ChannelsVOUT = VS/2, ISINKING = 40mA, ISOURCING = POWER SUPPLYO perating RangeVS718 VTotal Analog Supply CurrentISNo Load1828mAover Temperature28mADIGITALL ogic 1 Input VSDVL ogic 0 Input VSDVL ogic 0 Output VoltageVOLISINK = Leakage 10 AClock FrequencyfCLKS tandard/Fast Mode400kHzHigh-Speed POWER SUPPLYO perating Voltage Supply Current(3)

6 ISDO utputs at Reset Values, No-Load, Two-Wire Bus Inactive2550 Aover Temperature100 ATEMPERATURES pecified Temperature Range 40+85 COperating Temperature RangeJunction Temperature < +125 C 40+95 CStorage Temperature Range 65+150 CThermal Resistance, HTSSOP-38 Junction-to-AmbientqJA30 C/WJunction-to-CaseqJC15 C/W(1)See typical characteristic Output Voltage vs Output Current.(2)See applications information section REFH and REFL Input Range.(3)See typical characteristic Digital Supply Current vs Temperature." #$%&%%SBOS329E JUNE 2005 REVISED DECEMBER CONFIGURATIONSTop ViewHTSSOP(1) NC denotes no connection.(2) GNDD and GNDA are internally connected and must be at the same Voltage OUT 2 REFHNC(1)NC(1)OUT 1 OUT 2 OUT 3 OUT 4 OUT 5 OUT 6 GNDA(2)VSOUT 7 OUT 8 OUT 9 REFH OUTVSDSCLSDAVCOM OUT 1 REFLNC(1)NC(1)REFL OUTOUT 18 OUT 17 OUT 16 OUT 15 OUT 14 GNDA(2)VSOUT 13 OUT 12 OUT 11 OUT 10 GNDD(2)LDAO12345678910111213141516171819 38373635343332313029282726252423222120 PowerPADLead FrameDie PadExposed onUnderside" #$%&%%SBOS329E JUNE 2005 REVISED DECEMBER CHARACTERISTICSAt TA = +25 C, VS = 18V, VSD = 5V, VREFH = 17V, VREFL = 1V, RL = connected to ground, and CL = 200pF, unless otherwise 11614121086420 Analog IQ(mA)ANALOG SUPPLY CURRENT vs TEMPERATURE 40 20010040608020 Temperature (_C)VS= 18 VVS= 10 VFigure 2302520151050 Digital IQ( A)DIGITAL SUPPLY CURRENT vs TEMPERATURE 40 20010040608020Te m p e r a t u r e (_C)VS= Voltage (5V/div)FULL SCALE OUTPUT SWINGTime (1 s/div)

7 REFH = 17 VREFL = 1 VCode 3FF 000 Code 000 3 FFFigure 3 Figure 4181716153210 Output Voltage (V)OUTPUT Voltage vs OUTPUT CURRENT0102010040506070809030 Output Current (mA)OUT1 9, VCOM1 2 (sinking)Code = 000hVREFL=1V,VREFH= 18 (sourcing), Code = 3 FFhVREFL= ,VREFH=17 VRLOADC onnected to GNDOUT10 18 (sinking), Code = 000hVREFL= ,VREFH= 17 VRLO ADConnected to 18 VOUT1 9, VCOM1 2 (sourcing)Code = 3 FFhVREFL=1V,VREFH= to Error (LSB)INTEGRAL NONLINEARITY ERROR vs INPUT CODE02001000400600800 Input CodeFigure Error (LSB)DIFFERENTIAL NONLINEARITY ERROR vs INPUT CODE02001000400600800 Input CodeFigure 6" #$%&%%SBOS329E JUNE 2005 REVISED DECEMBER INFORMATIONThe BUF20800 programmable Voltage reference allowsfast, easy adjustment of 18 programmable referenceoutputs and two channels for vcom adjustment, each with10-bit resolution. It offers very simple, time-efficientadjustment of the Gamma reference and vcom BUF20800 is programmed through a high-speed,standard, two-wire interface.

8 The BUF20800 features adouble-register structure for each DAC channel to simplifythe implementation of dynamic Gamma control. Thisstructure allows pre-loading of register data and rapidupdating of all channels 1 9 are able to swing to within 200mV of thepositive supply rail, and to within of the negativesupply rail. Buffers 10 18 are able to swing to within the positive supply rail and to within 200mV of thenegative supply BUF20800 can be powered using an analog supplyvoltage from 7V to 18V, and a digital supply from 2V The digital supply must be applied prior to orsimultaneously with the analog supply to avoid excessivecurrent and power consumption; damage to the devicemay occur if it is left connected only to the analog supplyfor extended periods of time. Figure 7 shows the powersupply timing Supply:Analog Supply:t1: 0s minimum delay between Digital Supply and Analog 7.

9 Power Supply Timing RequirementsFigure 8 shows the BUF20800 in a typical this configuration, the BUF20800 device address is output of each digital-to-analog converter (DAC) isimmediately updated as soon as data are received in thecorresponding register (LD = 0). For maximum dynamicrange, set VREFH = VS and VREFL = GND + BUS OVERVIEWThe BUF20800 communicates through an industry-standard, two-wire interface to receive data in slave standard uses a two-wire, open-drain interface thatsupports multiple devices on a single bus. Bus lines aredriven to a logic low level only. The device that initiates thecommunication is called a master, and the devicescontrolled by the master are slaves. The master generatesthe serial clock on the clock signal line (SCL), controls thebus access, and generates the START and address a specific device, the master initiates a START condition by pulling the data signal line (SDA) from a HIGHto a LOW logic level while SCL is HIGH.

10 All slaves on thebus shift in the slave address byte, with the last bitindicating whether a read or write operation is the 9th clock pulse, the slave being addressedresponds to the master by generating an Acknowledgeand pulling SDA transfer is then initiated and eight bits of data are sentfollowed by an Acknowledge Bit. During data transfer,SDA must remain stable while SCL is HIGH. Any changein SDA while SCL is HIGH will be interpreted as a STARTor STOP all data has been transferred, the master generatesa STOP condition indicated by pulling SDA from LOW toHIGH while SCL is BUF20800 can act only as a slave device; therefore,it never drives SCL. SCL is only an input for the 1 and Table 2 summarize the address andcommand codes, respectively, for the THE BUF20800 The address of the BUF20800 is 111010x, where x is thestate of the A0 pin.