19-3624; Rev 0; 3/05 KIT ATION EVALU LE B A IL A AV EEPROM-Programmable TFT VCOM Calibrator with I2C Interface Features ♦ 7-Bit Adjustable Sink-Current Output ♦ Resistor-Adjustable, Full-Scale Range ♦ Guaranteed Monotonic Output Over Operating Range ♦ 2-Wire I2C Interface ♦ EEPROM Stores VCOM Setting ♦ 4.5V to 20V Analog Supply Voltage Range (VAVDD) ♦ 60µA (max) AVDD Supply Current ♦ 16.1V to 28V EEPROM Programming Supply Voltage Range (VHV) ♦ <1µA HV Supply Current (Not in Program Mode) ♦ 8-Pin µMAX Ordering Information TEMP RANGE PIN-PACKAGE MAX8738EUA PART -40oC to +85oC 8 µMAX MAX8738EUA+ -40oC to +85oC 8 µMAX +Denotes lead-free package. Applications Typical Operating Circuit LCD Panels +3.3V Notebook Computers VGON Display Products LCD TVs VDD HV AVDD SDA µMAX is a registered trademark of Maxim Integrated Products, Inc. Pin Configuration I2C R1 BUS MAX8738 OUT SCL GND TOP VIEW AVDD SET R2 VCOM RSET OUT 1 8 SET 7 SCL 3 6 SDA GND 4 5 HV AVDD 2 MAX8738 VDD µMAX Purchase of I2C components from Maxim Integrated Products, Inc., or one of its sublicensed Associated Companies, conveys a license under the Philips I2C Patent Rights to use these components in an I2C system, provided that the system conforms to the I2C Standard Specification as defined by Philips. ________________________________________________________________ Maxim Integrated Products For pricing, delivery, and ordering information, please contact Maxim/Dallas Direct! at 1-888-629-4642, or visit Maxim’s website at www.maxim-ic.com. 1 MAX8738 General Description The MAX8738 is an I2C-programmable VCOM-adjustment solution for thin-film transistor (TFT) liquid-crystal displays (LCDs). The MAX8738 simplifies the labor-intensive VCOM-adjustment process and replaces mechanical potentiometers, which significantly reduces labor costs, increases reliability, and enables automation. The MAX8738 attaches to an external resistive voltagedivider and sinks a programmable current to set the VCOM voltage level. An internal 7-bit digital-to-analog converter (DAC) controls the sink current. The DAC is ratiometric relative to AVDD and is guaranteed to be monotonic over all operating conditions. This VCOM calibrator IC includes an EEPROM to store the desired VCOM voltage level. The EEPROM can be programmed repeatedly, giving TFT LCD manufacturers the flexibility to calibrate the display panel as many times as the manufacturing process requires. The MAX8738 features a 2-wire I2C* interface for DACadjustment commands and EEPROM programming. The interface utilizes the existing I2C bus on the LCD panel connector so no additional panel connector pins are required. The MAX1512 is a similar product with a 1-wire interface and is recommended for applications with no existing I2C interface. The MAX8738 is available in an 8-pin µMAX® package. A complete evaluation kit is available to simplify evaluation and production development. MAX8738 EEPROM-Programmable TFT VCOM Calibrator with I2C Interface ABSOLUTE MAXIMUM RATINGS VDD, SET, SCL, SDA to GND....................................-0.3V to +6V OUT to GND ...........................................................-0.3V to +18V AVDD, HV to GND ..................................................-0.3V to +30V Continuous Power Dissipation 8-Pin µMAX (derate 4.5mW/ °C above +70°C) ............362mW Operating Temperature Range ...........................-40°C to +85°C Junction Temperature ......................................................+150°C Storage Temperature Range .............................-65°C to +160°C Lead Temperature (soldering, 10s) .................................+300°C Stresses beyond those listed under “Absolute Maximum Ratings” may cause permanent damage to the device. These are stress ratings only, and functional operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to absolute maximum rating conditions for extended periods may affect device reliability. ELECTRICAL CHARACTERISTICS (VAVDD = 15V, VHV = 20V, VOUT = 6.75V, RSET = 30.1kΩ, TA = 0°C to +85°C, unless otherwise noted.) (Figure 1) PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS +1 LSB +2 LSB +4 LSB 120 µA SINK CURRENT ADJUSTMENT SET Voltage Resolution 7 SET Differential Nonlinearity Monotonic overtemperature SET Zero-Scale Error -1 SET Full-Scale Error -4 SET Current ISET SET External Resistance (Note 1) RSET +1 To GND, VAVDD = 20V 10 200 To GND, VAVDD = 4.5V 2.25 45.00 DAC full scale VSET/VAVDD Voltage Ratio Bits -1 Factory set 0.05 0.024 0.025 0.026 kΩ V/V 2-WIRE INTERFACE Logic-Input Low Voltage VIL SDA, SCL Logic-Input High Voltage VIH SDA, SCL 0.8 V 2.1 V mA Logic-Output Low Sink Current SDA forced to 0.4V 6 Logic-Input Current VSDA = +3.3V or GND, VSCL = +3.3V or GND -1 SDA and SCL Input Capacitance SDA, SCL +1 5 µA pF SCL Frequency fCLK DC SCL High Time tCLH 4000 100 ns SCL Low Time tCLL 4700 ns SDA and SCL Rise Time tR (Note 2) 1000 SDA and SCL Fall Time tF (Note 2) 300 START Condition Hold Time tHDSTT 10% of SDA to 90% of SCL 4000 kHz ns ns ns START Condition Setup Time tSUSTT 4700 ns Data Input Hold Time tHDDAT 0 ns Data Input Setup Time tSUDAT 250 ns STOP Condition Setup Time ns tSUSTP 4000 Bus Free Time tBF 4700 Input Filter Spike Suppression tSP SDA, SCL (Note 2) ns 1 µs VDD REGULATOR VDD Output Voltage VDD Power-On Reset Threshold 2 VDD 4.5V < VAVDD < 20V, IVDD = 0 3.1 3.6 Rising edge, 100mV hysteresis _______________________________________________________________________________________ 4.5 V 3.0 V EEPROM-Programmable TFT VCOM Calibrator with I2C Interface (VAVDD = 15V, VHV = 20V, VOUT = 6.75V, RSET = 30.1kΩ, TA = 0°C to +85°C, unless otherwise noted.) (Figure 1) PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS 20.0 V 25 60 µA 28.0 V Rising edge, 60mV hysteresis 15.6 16.0 V Not in program mode (Note 3) 0.1 1 Program mode (Note 3) 15 AVDD SUPPLY AVDD Supply Range VAVDD AVDD Operating Current IAVDD 4.5 VAVDD = 20V HV SUPPLY HV Input Voltage Range VHV HV Power-On Reset Threshold HV Input Bias Current IHV 16.1 During program (Note 4) 30 µA 60 OUTPUT VOLTAGE OUT Leakage Current OUT Settling Time To ±0.5 LSB error band OUT Voltage Range ±100 nA 20 µs VSET + 0.5V VOUT 13 V ELECTRICAL CHARACTERISTICS (VAVDD = 15V, VHV = 20V, VOUT = 6.75V, RSET = 30.1kΩ, TA = -40°C to +85°C, unless otherwise noted.) (Figure 1) (Note 5) PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS -1 +1 LSB SET Zero-Scale Error -1 +2 LSB SET Full-Scale Error -4 +4 LSB 120 µA SINK CURRENT ADJUSTMENT SET Differential Nonlinearity Monotonic overtemperature SET Current ISET SET External Resistance (Note 1) RSET To GND, VAVDD = 20V 10 200 To GND, VAVDD = 4.5V 2.25 45.00 kΩ 2-WIRE INTERFACE Logic-Input Low Voltage VIL SDA, SCL Logic-Input High Voltage VIH SDA, SCL Logic-Output Low Sink Current Logic-Input Current ILI 0.8 V 2.1 V SDA forced to 0.4V 6 mA VSDA = +3.3V or GND, VSCL = +3.3V or GND -1 +1 µA 100 kHz SCL Frequency fCLK DC SCL High Time tCLH 4000 ns SCL Low Time tCLL 4700 ns SDA and SCL Rise Time tR (Note 2) 1000 ns SDA and SCL Fall Time tF (Note 2) 300 ns _______________________________________________________________________________________ 3 MAX8738 ELECTRICAL CHARACTERISTICS (continued) MAX8738 EEPROM-Programmable TFT VCOM Calibrator with I2C Interface ELECTRICAL CHARACTERISTICS (continued) (VAVDD = 15V, VHV = 20V, VOUT = 6.75V, RSET = 30.1kΩ, TA = -40°C to +85°C, unless otherwise noted.) (Figure 1) (Note 5) PARAMETER SYMBOL START Condition Hold Time tHDSTT CONDITIONS 10% of SDA to 90% of SCL MIN TYP MAX 4000 UNITS ns START Condition Setup Time tSUSTT 4700 ns Data Input Hold Time tHDDAT 0 ns Data Input Setup Time tSUDAT 250 ns STOP Condition Setup Time tSUSTP 4000 ns tBF 4700 ns Bus Free Time VDD REGULATOR VDD Output Voltage VDD VDD Power-On Reset Threshold 4.5V < VAVDD < 20V, IVDD = 0 3.1 Rising edge, 100mV hysteresis 4.5 V 3.0 V AVDD SUPPLY AVDD Supply Range VAVDD AVDD Operating Current IAVDD 4.5 20.0 V 60 µA VAVDD = 20V HV SUPPLY HV Input Voltage Range VHV HV Power-On Reset Threshold 16.1 Rising edge, 60mV hysteresis HV Input Bias Current IHV 28.0 V 16.0 V Not in program mode (Note 3) 1 Program mode (Note 3) 30 During program (Note 4) 60 µA OUTPUT VOLTAGE OUT Voltage Range Note 1: Note 2: Note 3: Note 4: Note 5: VSET + 0.5V VOUT 13 SET resistors are only checked at full scale. Guaranteed by design. Not production tested. The MAX8738 enters program mode after any valid command is received, except the AAh command. Program time lasts for 11ms. Specifications from 0°C to -40°C are guaranteed by design, not production tested. tHDSTT tR tCLH tCLL SCL tF SDA tHDDAT tSUDAT tSUSTP VIH VIL Figure 1. Timing Definitions Used in the Electrical Characteristics 4 _______________________________________________________________________________________ tBF V EEPROM-Programmable TFT VCOM Calibrator with I2C Interface (VAVDD = 9V, VHV = 18V, RSET = 24.9kΩ, TA = unless otherwise noted.) AVDD SUPPLY CURRENT vs. TEMPERATURE 100 VAVDD = 4.5V 10 1 0 20 40 60 80 100 0.4 0.3 0.2 0.1 0 0.1 -20 -40 MAX8738 toc03 MAX8738 toc02 0.5 IOUT SINK-CURRENT ERROR (LSB) 20 15 1 0.1 10 100 4 1000 8 12 20 16 TEMPERATURE (°C) RSET (kΩ) VAVDD (V) IOUT SINK-CURRENT ERROR vs. VOUT IOUT SINK-CURRENT ERROR vs. TEMPERATURE TOTAL UNADJUSTED ERROR vs. DAC SETTING 0.2 0.1 0.3 0.2 0.1 VAVDD = 9V 1 10 -40 -20 0 VOUT (V) 20 40 60 80 0 -0.1 -0.2 -0.3 0 100 16 32 48 0.2 0.1 0 -0.1 -0.2 -0.3 0.4 0.3 0 -0.1 -0.2 -0.3 -0.4 -0.5 48 64 80 DAC SETTING 96 112 128 0.1 -0.5 32 96 0.2 -0.4 16 80 112 128 MAX8738 toc08 0.3 0.5 DIFFERENTIAL NONLINEARITY (LSB) 0.4 64 DAC SETTING DIFFERENTIAL NONLINEARITY vs. DAC SETTING MAX8738 toc07 0.5 INTEGRAL NONLINEARITY (LSB) 0.1 TEMPERATURE (°C) INTEGRAL NONLINEARITY vs. DAC SETTING 0 0.2 -0.5 0 0.1 0.3 -0.4 VAVDD = 9V 0 MAX8738 toc06 0.4 0.4 TOTAL UNADJUSTED ERROR (LSB) 0.3 0.5 MAX8738 toc05 0.4 0.5 IOUT SINK-CURRENT ERROR (LSB) MAX8738 toc04 0.5 IOUT SINK-CURRENT ERROR (LSB) IOUT SINK-CURRENT ERROR vs. VAVDD VAVDD = 20V FULL-SCALE IOUT (µA) VAVDD = 9V AVDD SUPPLY CURRENT (µA) FULL-SCALE IOUT vs. RSET 1000 MAX8738 toc01 25 0 16 32 48 64 80 96 112 128 DAC SETTING _______________________________________________________________________________________ 5 MAX8738 Typical Operating Characteristics +25°C, MAX8738 EEPROM-Programmable TFT VCOM Calibrator with I2C Interface Typical Operating Characteristics (continued) (VAVDD = 9V, VHV = 18V, RSET = 24.9kΩ, TA = +25°C, unless otherwise noted.) AVDD POWER-UP RESPONSE AVDD POWER-DOWN RESPONSE MAX8738 toc09 SINGLE LSB STEP-UP RESPONSE MAX8738 toc10 9V MAX8738 toc11 9V A 0 A B 3.6V C 4V A 0 B 0 B 0 C C 0 D 325mV D D 0 0 20µs/div A. VAVDD, 5V/div B. VOUT, 2V/div 5ms/div C. VDD, 2V/div D. VSET, 0.2V/div A. VAVDD, 5V/div B. VOUT, 2V/div SINGLE LSB STEP-DOWN RESPONSE 50µs/div WRITE 00H RESPONSE MAX8738 toc12 B 0 C. VSET, 5mV/div D. VOUT, 5mV/div WRITE FFH RESPONSE MAX8738 toc13 A 0 A. SCL, 5V/div B. SDA, 5V/div C. VDD, 2V/div D. VSET, 0.2V/div MAX8738 toc14 A 0 B 0 3.95V A 0 B 0 3.95V C C C 3.45V 3.45V 400mV 450mV D D D 0 0 50µs/div A. SCL, 5V/div B. SDA, 5V/div 6 C. VSET, 5mV/div D. VOUT, 5mV/div 50µs/div A. SCL, 5V/div B. SDA, 5V/div C. VOUT, 500mV/div D. VSET, 200mV/div 50µs/div A. SCL, 5V/div B. SDA, 5V/div _______________________________________________________________________________________ C. VOUT, 500mV/div D. VSET, 200mV/div EEPROM-Programmable TFT VCOM Calibrator with I2C Interface PIN NAME FUNCTION 1 OUT Adjustable Sink-Current Output. OUT connects to the resistive voltage-divider between AVDD and GND that sets the VCOM voltage. IOUT lowers the divider voltage by an adjustable amount. See the SET pin description. 2 AVDD 3 VDD 4 GND High-Voltage Analog Supply. Bypass to GND with a 0.1µF capacitor. 3.6V Regulator Output. VDD provides the supply voltage to the entire IC. VDD is not for external use. Bypass to GND with a 0.1µF capacitor. Ground. Connect to system ground. EEPROM High-Voltage Programming Supply. Bypass to GND with a 0.1µF capacitor. Connect this pin to the TFT LCD VGON supply. VGON should be between 16.1V and 28V. The HV pin supplies the power for the internal EEPROM writing cycle. The internal writing circuits are disabled when HV is less than 15.6V (typ). 5 HV 6 SDA I2C-Compatible Clock Input 7 SCL I2C-Compatible Serial Bidirectional Data Line Full-Scale Sink-Current Adjustment Input. Connect a resistor, RSET, from SET to GND to set the full-scale adjustable sink current. The full-scale adjustable sink current is equal to: 8 ⎛ V ⎞ AVDD ⎜ ⎟ ⎝ 20 × RSET ⎠ SET IOUT is equal to the current through RSET. VGON 0.1µF 0.1µF +3.3V 2 x 3.9kΩ VDD HV 0.1µF AVDD SDA I 2C BUS AVDD R1 64.9kΩ MAX8738 SCL OUT GND SET R2 51.1kΩ VCOM RSET 24.9kΩ Figure 2. Standard Application Circuit _______________________________________________________________________________________ 7 MAX8738 Pin Description MAX8738 EEPROM-Programmable TFT VCOM Calibrator with I2C Interface AVDD +3.3V VDD LINEAR REGULATOR AVDD 19R R1 MAX8738 SDA I2C BUS SCL OUT 7 I2C CONTROL INTERFACE R DAC 7 R2 VCOM SET EEPROM BLOCK VGON RSET HV GND Figure 3. Simplified Functional Diagram Detailed Description The MAX8738 is a solid-state alternative to mechanical potentiometers used for adjusting the LCD backplane voltage (VCOM) in TFT LCD displays. The MAX8738 attaches to an external resistive voltage-divider and sinks a programmable current (IOUT), which sets the VCOM level (Figure 2). An internal 7-bit DAC controls the sink current and allows the user to increase or decrease the VCOM level (Figure 3). The DAC is ratiometric relative to VAVDD and is monotonic over all operating conditions. The user can store the DAC setting in an internal EEPROM. On power-up, the EEPROM presets the DAC to the last stored setting. The 2-wire I2C interface between the LCD panel and the programming circuit adjusts the DAC and programs the EEPROM. The resistive voltage-divider and the AVDD supply set the maximum value of VCOM. The MAX8738 sinks current from the voltage-divider to reduce the VCOM level. The external resistor RSET sets the full-scale sink current and the minimum value of VCOM. Supply Voltages AVDD and VDD The MAX8738 has an internal linear regulator that generates a 3.6V VDD voltage from the AVDD supply voltage. The VDD voltage supplies power to the MAX8738 and should not be used for external loads. AVDD accepts voltages from 4.5V to 20V. Bypass AVDD and VDD to GND with a 0.1µF capacitor each. 8 HV The HV input provides the high voltage required to program the EEPROM. The HV pin is typically connected to the TFT LCD positive gate driver supply (VGON) supply. VGON should be between 16.1V and 28V. EEPROM programming is disabled when HV is below 15.6V (typ). Bypass HV to GND with a 0.1µF capacitor. The EEPROM programming block is turned off when the MAX8738 first powers up, and also immediately after the EEPROM is programmed. When the EEPROM programming block is off, the HV supply current is less than 1µA. After the MAX8738 receives any command that changes the DAC value, the EEPROM programming block is enabled, and the HV supply current increases to 15µA (typ). During the programming of the EEPROM, the HV supply current may draw up to 60µA (max). Setting the VCOM Adjustment Range (RSET) The external resistive voltage-divider sets the maximum value of the VCOM adjustment range. RSET sets the full-scale sink current, IOUT, which determines the minimum value of the VCOM adjustment range. Large RSET values increase resolution but decrease the VCOM adjustment range. Calculate R1, R2, and RSET using the following procedure: _______________________________________________________________________________________ EEPROM-Programmable TFT VCOM Calibrator with I2C Interface 7) The resulting resolution is: MAX8738 1) Choose the maximum VCOM level (VMAX), the minimum VCOM level (V MIN), and the AVDD supply voltage (VAVDD). (VMAX − VMIN ) 2) Select R1 between 10kΩ and 500kΩ based on the acceptable power loss from the AVDD supply rail. 127 A complete design example is given below: 1) VMAX = 5V, VMIN = 3V, VAVDD = 10V. 3) Calculate R2: R2 ≅ VMAX (VAVDD − VMAX ) × R1 3) ISET(MAX) = 20µA. 4) Calculate RSET: RSET = 2) If R1 = 200kΩ, then R2 = 200kΩ and RSET = 24.9kΩ. 4) Resolution = 15.75mV. VMAX 20 × (VMAX − VMIN ) 5) Verify that ISET(MAX) does not exceed 120µA: ISET(MAX) = Translating Existing Potentiometer Circuits × R1 VAVDD ≤ 120µA 20 × RSET Existing VCOM adjustment circuits using conventional mechanical potentiometers can be translated into MAX8738 circuits. Figures 4 and 5 show two common adjustment circuits and their equivalent MAX8738 circuits. 6) If ISET exceeds 120µA, return to step 2 and choose a larger value for R1. MAX8738 EQUIVALENT CIRCUIT MECHANICAL POTENTIOMETER AVDD RA AVDD RB AVDD VCOM R1 MAX8738 RC OUT R1 = RA R2 = RB + RC R x (RB + RC) RSET = A 20 x RB GND SET R2 VCOM RSET Figure 4. Replacement of Mechanical Potentiometer Circuit _______________________________________________________________________________________ 9 MAX8738 EEPROM-Programmable TFT VCOM Calibrator with I2C Interface MECHANICAL POTENTIOMETER MAX8738 EQUIVALENT CIRCUIT AVDD RD AVDD RE AVDD VCOM R1 MAX8738 RF OUT GND R1 = RD R2 = RF RSET = SET R2 VCOM RSET RD x (RD + RE + RF) 20 x RE Figure 5. Replacement of Mechanical Potentiometer Circuit Applications Information I2C-Bus-Compatible Interface The MAX8738 is a receive-only device with an I 2 C address of 5Eh. The 2-wire, I2C-bus-compatible serial interface (pins SCL and SDA) is designed to attach to a I2C bus. Connect both SCL and SDA lines to the positive bus supply through individual pullup resistors. Calculate the required value of the pullup resistors using: RPULLUP ≤ tR CBUS where t R is the rise time in the Electrical Characteristics, and CBUS is the total capacitance on the bus. The MAX8738 is compatible with the standard I2C interface protocol as defined in the following subsections. See Figure 6. Bus Not Busy The I2C bus is not busy when both data and clock lines remain HIGH. Data transfers may be initiated only when the bus is not busy. START Data Transfer (S) Starting from an idle bus state (both SDA and SCL are high), a START condition consists of a HIGH to LOW transition of the SDA line while the clock (SCL) is HIGH. All commands must be preceded by a START condition. STOP Data Transfer (P) A STOP condition consists of a LOW to HIGH transition of the SDA line while the clock (SCL) is HIGH. All operations must be ended with a STOP condition. SDA SCL S START CONDITION DATA LINE STABLE DATA VALID CHANGE OF DATA ALLOWED P STOP CONDITION Figure 6. I2C Bus START, STOP, and Data Change Conditions 10 ______________________________________________________________________________________ EEPROM-Programmable TFT VCOM Calibrator with I2C Interface SDA Data Valid The state of the data line represents valid data when, after a START condition, the data line is stable for the duration of the HIGH period of the clock signal. The data on the line must be changed during the LOW period of the clock signal. There is one clock pulse per bit of data. Acknowledge Each receiving device, when addressed, is obliged to generate an acknowledge after the reception of each DATA OUTPUT BY MASTER D7 D6 byte. The master device must generate an extra clock pulse that is associated with this acknowledge bit. The device that acknowledges has to pull down the SDA line during the acknowledge clock pulse so that the SDA line is stable LOW during the HIGH period of the acknowledge-related clock pulse. Of course, setup and hold times must be taken into account. See Figure 7. The MAX8738 does not acknowledge the program EEPROM command (AAh) if HV is below 15.6V (typ) or if the MAX8738 is not in program mode. The MAX8738 does not acknowledge any command while an internal programming cycle is in progress. Once the internally timed EEPROM write cycle has started, acknowledge polling can be initiated. This involves repeatedly sending a 55h command. Only if the internal write cycle has completed does the MAX8738 acknowledge the command. D0 NOT ACKNOWLEDGE DATA OUTPUT BY MAX8738 ACKNOWLEDGE SCL FROM MASTER S START CONDITION 1 2 8 9 CLK1 CLK2 CLK8 CLK9 ACKNOWLEDGE CLOCK PULSE Figure 7. I2C Bus Acknowledge ______________________________________________________________________________________ 11 MAX8738 Slave Address After generating a START condition, the bus master transmits the slave address consisting of a 7-bit device code (0b0101111 or 5Eh) for the MAX8738. Since the MAX8738 is a write-only device, the eighth bit of the slave address is zero. The MAX8738 monitors the bus for its corresponding slave address continuously. It generates an acknowledge bit when it recognizes its address. MAX8738 EEPROM-Programmable TFT VCOM Calibrator with I2C Interface Table 1. Command Byte Functions BYTE FUNCTION Table 2. DAC Settings FIGURE DAC VALUE ISET VSET (V) VOUT (V) FFh ISET(MAX) VSET(MAX) VMIN FEh ISET(MAX) 1 LSB VSET(MAX) 1 LSB VMIN + 1 LSB . . . . . . . . . . . . 01h ISET(MIN) + 1 LSB VSET(MIN) + 1 LSB VMAX 1 LSB 00h ISET(MIN) VSET(MIN) VMAX 00h Decrement the DAC setting by 1 LSB 8A FFh Increment the DAC setting by 1 LSB 8A AAh Write the current DAC setting to EEPROM 8A 55h Load the EEPROM setting to the DAC 8A 11h Write a specific value to the DAC 8B Command Byte A complete command consists of a START condition (S) followed by the MAX8738’s slave address (5Eh) and a command byte, or a command byte and a DAC value, followed by a STOP condition (P). There are five commands, and their functions are listed in Table 1. DAC Values Table 2 lists the DAC values and the corresponding ISET, VSET, and VOUT values. 3) Bypass V DD and AVDD with 0.1µF capacitors placed close to the IC with short connections to the pins. 4) Refer to the MAX8738 evaluation kit for an example of proper board layout. Layout Information Chip Information Use the following guidelines for good layout: 1) Place the VCOM buffer and the R1/R2 voltagedivider close to the OUT pin (Figure 2). TRANSISTOR COUNT: 6198 PROCESS: BiCMOS 2) Place RSET close to SET. START S STOP SLAVE ADDRESS COMMAND BYTE ACK P ACK (A) FOR THE 00H, FFH, AAH, AND 55H COMMANDS STOP START S SLAVE ADDRESS SET DAC VALUE (11H) ACK DAC VALUE ACK (B) FOR THE DAC INITIAL VALUE-SETTING COMMAND Figure 8. I2C Bus Data Transfer Summary 12 ______________________________________________________________________________________ P ACK EEPROM-Programmable TFT VCOM Calibrator with I2C Interface E Ø0.50±0.1 8 INCHES DIM A A1 A2 b H c D e E H 0.6±0.1 1 L 1 α 0.6±0.1 S BOTTOM VIEW D MIN 0.002 0.030 MAX 0.043 0.006 0.037 0.010 0.014 0.005 0.007 0.116 0.120 0.0256 BSC 0.116 0.120 0.188 0.198 0.016 0.026 0∞ 6∞ 0.0207 BSC 8LUMAXD.EPS 4X S 8 MILLIMETERS MAX MIN 0.05 0.75 1.10 0.15 0.95 0.25 0.36 0.13 0.18 2.95 3.05 0.65 BSC 2.95 3.05 4.78 5.03 0.41 0.66 0∞ 6∞ 0.5250 BSC TOP VIEW A1 A2 e A α c b L SIDE VIEW FRONT VIEW PROPRIETARY INFORMATION TITLE: PACKAGE OUTLINE, 8L uMAX/uSOP APPROVAL DOCUMENT CONTROL NO. 21-0036 REV. J 1 1 Maxim cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim product. No circuit patent licenses are implied. Maxim reserves the right to change the circuitry and specifications without notice at any time. Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600 ____________________ 13 © 2005 Maxim Integrated Products Printed USA is a registered trademark of Maxim Integrated Products, Inc. MAX8738 Package Information (The package drawing(s) in this data sheet may not reflect the most current specifications. For the latest package outline information, go to www.maxim-ic.com/packages.)