LP5520 RGB Backlight LED Driver General Description Features The LP5520 is an RGB backlight LED driver for small format color LCDs. RGB backlight enables better colors on the display and power savings compared with white LED backlight. LP5520 offers small and simple driver solution without need for optical feedback. Calibration in display module production can be done in one temperature. LP5520 produces true white light over wide temperature range. Three independent LED drivers have accurate programmable current sinks and PWM modulation control. Using internal calibration memory and external temperature sensor, the RGB LED currents are adjusted for perfect white balance independent of the brightness setting or temperature. The user programmable calibration memory has intensity vs. temperature data for each color. This white balance calibration data can be programmed to the memory on the production line of a backlight module. The device has a magnetic boost converter that creates up to 20V LED supply voltage from the battery voltage. The output can be set at 1V step from 5V to 20V. In adaptive mode the circuit automatically adjusts the output voltage to minimum sufficient level for lowest power consumption. Temperature is measured using an external temperature sensor placed close to the LEDs. The second ADC input can be used e.g. for ambient light measurement. LP5520 is available in 25 pin microSMD™ package. ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ Temperature compensated LED intensity and color Individual calibration coefficients for each color Color accuracy ΔX and ΔY ≤ 0.003 12 bit ADC for measurement of 2 sensors Adjustable current outputs for R, G and B LED 0.2% typical LED output current matching PWM control inputs for each color SPI and I2C compatible interface Stand-alone mode with 1 wire control Sequential mode for one color at a time Magnetic high efficiency boost converter Programmable output voltage from 5V to 20V Adaptive output voltage control option < 2 µA typical shutdown current MicroSMD-25 package, 2.77 × 2.59 × 0.6mm Applications ■ ■ ■ ■ Color LCD display backlighting LED lighting applications Non-linear temperature compensation Ambient light compensation Typical Application 20186107 © 2007 National Semiconductor Corporation 201861 www.national.com LP5520 RGB Backlight LED Driver May 2007 LP5520 Connection Diagrams Thin microSMD-25 Package, Large Bump NS Package Number TLA25EMA 2.77 x 2.59 × 0.6 mm 20186108 20186109 Top View Bottom View 20186196 Package Mark – Top View Ordering Information www.national.com Order Number Package Marking Supplied As Spec/Flow LP5520TL 5520 250 units, Tape-and-Reel NoPb LP5520TLX 5520 3000 units, Tape-and-Reel NoPb 2 LP5520 Pin Descriptions Pin Name Type Description 5E SW Output Boost Converter Power Switch 5D FB Input Boost Converter Feedback 5C VDDD Power Supply Voltage for Digital Circuitry 5B SI/A0 Logic Input Serial Input (SPI), Address Select (I2C) 5A SO Logic Output Serial Data Out (SPI) 4E GND_SW Ground Power Switch Ground 4D PWMR Logic Input PWM control for Output R 4C IFSEL Logic Input Interface Selection (SPI or I2C compatible, IF_SEL = 1 for SPI) 4B SCK/SCL Logic Input Clock (SPI/I2C) 4A SS/SDA Logic Input/Output Slave Select (SPI), Serial Data In/Out (I2C) 3E GND_LED Ground Ground for LED Currents 3D GNDA Ground Ground for Analog Circuitry 3C PWMG Logic Input PWM control for Output G 3B NRST Logic Input Master Reset, Active Low 3A VDDIO Power Supply Voltage for Input/output Buffers and Drivers 2E ROUT Output Red LED Output 2D PWMB Logic Input PWM control for Output B 2C S2_IN Input ADC input 2, input for optional second sensor 2B BRC Logic Input Brightness Control for All LED Outputs, Pseudo-PWM 2A VLDO Power Internal LDO Output 1E GOUT Output Green LED Output 1D BOUT Output Blue LED Output 1C S1_IN Input ADC input 1, input for temperature sensor 1B GNDT Ground Ground/Test 1A VDDA Power Supply Voltage for Analog Circuitry 3 www.national.com LP5520 Human Body Model: Machine Model: Absolute Maximum Ratings (Notes 1, 2) If Military/Aerospace specified devices are required, please contact the National Semiconductor Sales Office/ Distributors for availability and specifications. V (SW, FB, ROUT, GOUT, BOUT) VDDA, VDDD, VDDIO, VLDO Voltage on Logic Pins Operating Ratings (Notes 1, 2) V (SW, FB, MAIN, SUB) 0 to 21V VDDA,DDD 2.9 to 5.5V VDDIO 1.65V to VDDA Recommended Load Current (ROUT, GOUT, BOUT) 0 mA to 60 mA /driver Junction Temperature (TJ) Range -30°C to 125°C Ambient Temperature (TA) Range (Note 6) -30°C to 85°C -0.3V to 22V -0.3V to 6.0V -0.3V to VDDIO 0.3V with 6.0V max Continuous Power Dissipation (Note 3) Junction Temperature (TJ-MAX) Storage Temperature Range Maximum Lead Temperature (Soldering) (Note 4) ESD Rating (Note 5) 2 kV 200V Internally Limited 125°C -65°C to 150°C Thermal Properties Junction-to-Ambient Thermal Resistance(θJA), TLA25 Package (Note 7) 60 - 100°C/W Electrical Characteristics (Notes 2, 8) Limits in standard typeface are for TJ = 25°C. Limits in boldface type apply over the operating ambient temperature range (-30°C < TJ < 85°C). Unless otherwise noted, specifications apply to the LP5520 Block Diagram with: CVDDA/D = 100 nF, COUT = 2 x 4.7 µF/ 25V, CIN= 10 µF / 6.3V, L1 = 4.7 µH (Note 9). Symbol Parameter Condition Min Typ Max Units 1.7 7 µA Standby supply current (VDDA + VDDD) NSTBY = L, VDDIO ≥ 1.65V 1 µA No-boost supply current (VDDA + VDDD) NSTBY = H, EN_BOOST = L 0.9 mA No-load supply current (VDDA + VDDD) NSTBY = H, EN_BOOST = H AUTOLOAD = L 1.4 mA IVDDIO VDDIO Standby Supply current NSTBY = L VLDO Internal LDO output voltage VIN ≥ 2.9V ILDO Internal LDO output current Current to external load IVDD NSTBY = L , VDDIO = 0V 1 2.77 2.80 µA 2.84 V 1 mA Note 1: Absolute Maximum Ratings indicate limits beyond which damage to the component may occur. Operating Ratings are conditions under which operation of the device is guaranteed. Operating Ratings do not imply guaranteed performance limits. For guaranteed performance limits and associated test conditions, see the Electrical Characteristics tables. Note 2: All voltages are with respect to the potential at the GND pins. Note 3: Internal thermal shutdown circuitry protects the device from permanent damage. Thermal shutdown engages at TJ=160°C (typ.) and disengages at TJ=140°C (typ.). Note 4: For detailed soldering specifications and information, please refer to National Semiconductor Application Note AN1112 : MicroSMD Wafer Level Chip Scale Package Note 5: The Human body model is a 100 pF capacitor discharged through a 1.5 kΩ resistor into each pin. The machine model is a 200 pF capacitor discharged directly into each pin. MIL-STD-883 3015.7 Note 6: In applications where high power dissipation and/or poor package thermal resistance is present, the maximum ambient temperature may have to be derated. Maximum ambient temperature (TA-MAX) is dependent on the maximum operating junction temperature (TJ-MAX-OP = 125°C), the maximum power dissipation of the device in the application (PD-MAX), and the junction-to ambient thermal resistance of the part/package in the application (θJA), as given by the following equation: TA-MAX = TJ-MAX-OP – (θJA × PD-MAX). Note 7: Junction-to-ambient thermal resistance is highly application and board-layout dependent. In applications where high maximum power dissipation exists, special care must be paid to thermal dissipation issues in board design. Note 8: Min and Max limits are guaranteed by design, test or statistical analysis. Typical numbers are not guaranteed but do represent the most likely norm. Note 9: Low-ESR Surface-Mount Ceramic Capacitors (MLCCs) used in setting electrical characteristics. www.national.com 4 LP5520 Block Diagram 20186111 Modes of Operation LP5520 has three different operating modes: Manual mode, Automatic mode and Stand-Alone mode. The Automatic mode has two sub modes, normal mode and sequential mode. In manual and automatic modes the chip is controlled <RGB_auto> (RBG control bit 3) <seq_mode[0:1]> (RBG control bits 6 and 7) through the serial interface. In standalone mode only BRC input needs to be controlled and all registers have the default values.The modes are controlled according to the following table. LP5520 Operating Mode 0 00 Manual mode 1 00 Automatic mode, normal operation (overlapping) 1 01, 10 or 11 Automatic mode, sequential operation with 2, 3 or 4 pulses per sequence MANUAL MODE In the manual mode the automatic LED intensity adjustment is not in use. The internal PWM control is disabled and the LEDs are driven with DC current. The user can set the LED currents through the serial port using three Current Control registers, current_control_R/G/B, and use the external PWM control inputs to adjust LED intensities if needed. There is an independent PWM control pin for each output. If PWM control is not used, the PWMR, PWMG and PWMR inputs should be tied to the VDDIO. All the functions implemented with the internal PWM control are unavailable in manual mode (logarithmic brightness control from PWM Control register, temperature compensation, fading, sequential mode). AUTOMATIC MODE In the automatic mode the LED intensities are controlled with the 12-bit PWM values obtained from the EEPROM memory according to the temperature information. PWM values are stored at 16°C intervals for the –40 to 120°C temperature range, and the PWM values for the intermediate temperatures are linearly interpolated. When creating white light from a RGB LED, the intention is to program PWM values, which keep the individual LED intensities constant in all temperatures. For possible other applications, other kind of PWM behavior can be programmed, and also the variable can be other than temperature if the sensor is changed to e.g. a light sensor. 12-bit ADC is used for the measurements. The ADC has two inputs S1_IN and S2_IN. The temperature measurement result from the S1_IN input is converted to EEPROM address 5 www.national.com LP5520 using the sensor calibration data from EEPROM. This EEPROM address is then used to get the PWM values for each output. The second input S2_IN can be used for example for ambient light measurement. The ADC data from selected input can be read through the serial interface. Control bit <comp_sel> can be used to select which input is used for compensation. Current setting for each LED comes from EEPROM in the automatic mode. The same current values should be programmed as were used in the calibration. Current control range is from 0 to 60 mA with 8-bit resolution and the step size is 235 µA. Common Brightness Control for all LEDs can be done using the pwm_brightness (05H) register. The pwm_brightness register makes 8 level logarithmic brightness control with 3 bits. An automatic fade function makes possible smooth turnon, turn-off and brightness changes of the LEDs. White balance is maintained during fading. A brightness correction value can be given for each LED. The PWM value obtained from the EEPROM memory will be multiplied by this correction value. This feature can be used for example for LED aging compensation or for color adjustment by user. These values are kept in R_correction (0AH), G_correction (0BH) and B_correction (0CH) registers. The correction multiplier can be between 0 and 2. Due to LED self-heating, the temperature sensor and the LED temperatures will differ. The difference depends on the thermal structure of the display module and the distance between the sensor and the LEDs. This temperature difference can be compensated by storing the temperature difference value at highest power (100% red LED PWM) in the EEPROM memory. The system then corrects the measured temperature based on the actual PWM value used. The correction assumes that the red LED PWM value is representing the whole RGB LED power consumption. Sequential (non-overlapping) drive is possible using external PWM control inputs to trigger a new sequence in each LED BRC duty cycle threshold values (%) increasing output. 60 mA maximum current setting makes possible 20 mA maximum averaged current for each output in the nonoverlapping mode. STAND-ALONE MODE In stand-alone mode the operation is controlled through a single PWM brightness input, BRC. After power-up or reset the LP5520 is ready for stand-alone operation without any setup through the serial interface. The stand-alone mode is entered with a rising edge in the BRC input. The boost converter will operate in adaptive mode. The LED current settings are read from EEPROM. The LED brightness is controlled with a PWM signal in the BRC input. The BRC PWM frequency should be between 2 and 10 kHz. The PWM signal in the BRC input is not used as such for the LED outputs, but it is converted to 3-bit value and a logarithmic brightness control is based on this 3-bit value, as shown in the following table. There is hysteresis in the conversion to avoid blinking when the BRC duty cycle is close to a threshold. When the PWM pulses end in the BRC input and the input stays low, the circuit will go to the stand-by mode. The following picture shows the waveforms in BRC input and ROUT output in the stand-alone mode. The circuit is in standby mode until the first rising edge in BRC input is detected. The circuit starts up and the outputs activate after 30 ms from the first rising edge in BRC. The BRC frequency is assumed to 2 kHz in this example giving 0.5 ms BRC period. When the duty cycle changes in BRC, it takes two BRC periods before the change is reflected in the output. When BRC goes permanently low, the circuit will enter stand-by mode after 15 ms from the last BRC pulse. All controls through the serial interface can be used in the stand-alone mode. The stand-alone mode must be inhibited in automatic and manual modes by writing the control bit <brc_off> high and by keeping BRC input low. Intensity (% of maximum) decreasing Recommended BRC PWM control values increasing decreasing 0.8 10 10 28 1.6 28 22 42 3.1 40 32 48 52 6.3 53 47 58 62 12.5 63 58 68 75 25 75 70 82 90 50 88 85 100 99 0 off 1 15 20 35 97 0 BRC input PWM duty cycle conversion to brightness control www.national.com 6 LP5520 20186112 LP5520 control and output waveforms in stand-alone mode 20186113 LP5520 connection in stand-alone mode Start-Up START-UP POWERING VDDD and VDDA should be tied together and turned on first. VDDIO must be turned on at the same time as VDDD or later. In the power off sequence VDDIO must be turned off before VDDD or at the same time. 20186115 Power-on signal timing 7 www.national.com LP5520 START-UP SEQUENCE RESET: In the RESET mode all the internal registers are reset to the default values and the chip goes to STANDBY mode after reset. <NSTBY> control bit is low after reset by default. Reset is entered always if NRST input is low or internal Power On Reset is active. Power On Reset (POR) will activate during the chip startup or when the supply voltage VDD falls below 1.5V. Once VDD rises above 1.5V, POR will inactivate and the chip will continue to the STANDBY mode. STANDBY: The STANDBY mode is entered if the register bit <NSTBY> is LOW. This is the low power consumption mode, when all circuit functions are disabled. Registers can be written in this mode and the control bits are effective immediately after power up. STARTUP: When <NSTBY> bit is written high or there is a rising edge in the BRC input, the INTERNAL STARTUP SEQUENCE powers up all the needed internal blocks (Vref, Bias, Oscillator etc..). To ensure the correct initialization, a 10 ms delay is generated by the internal state-machine after the trim EEPROM values are read. If the chip temperature rises too high, the Thermal Shutdown (TSD) disables the chip operation and STARTUP mode is entered until no thermal shutdown event is present. BOOST STARTUP: Soft start for boost output is generated in the BOOST STARTUP mode. The boost output is raised in PWM mode during the 20 ms delay generated by the state-machine. All LED outputs are off during the 20 ms delay to ensure smooth startup. The Boost startup is entered from Internal Startup Sequence if <EN_BOOST> is HIGH or from Normal mode when <EN_BOOST> is written HIGH. NORMAL: During NORMAL mode the user controls the chip using the Control Registers or the BRC input in stand-alone mode. The registers can be written in any sequence and any number of bits can be altered in a register in one write. 20186114 www.national.com 8 Typical Color Coordinates vs. Temperature for uncompensated RGB LED WHITE BALANCE CONTROL LP5520 is designed to provide spectrally rich white light using a three color RGB LED. White light is obtained when the Red, Green and Blue LED intensities are in proper balance. The LED intensities change independently with temperature. For maintaining the purity of the white color and the targeted total intensity, precise temperature dependent intensity control for each LED is required. The color coordinates in this document refer to the CIE 1931 color graph (x,y system). CIE 1931 Color Graph 20186199 The compensation values for the measured temperatures can be easily calculated when the intensity vs. temperature information is available. For the best accuracy the iterative calibration approach should be used. The calibration procedure is described in the Application Note AN1459, LP5520 RGB Backlight Driver Calibration. Compensation PWM Values 20186197 The Intensity vs. Temperature graph shows a typical RGB LED intensity behavior on a 12-bit scale (0 to 4095) at constant 20mA LED currents. The next graph shows the typical color coordinate change for an uncompensated RGB LED. The Compensation PWM Values graph shows the corresponding PWM values for achieving constant intensity white light across the temperature range. The PWM values have been saturated at 104°C to avoid overheating the LED and to better utilize the PWM range. The white balance is not maintained above 104°C in this case. LED Intensity vs. Temperature 20186135 The compensation values need to be converted to 16°C intervals when they are programmed to the calibration EEPROM. The evaluation software has import function, which can be used to convert the measured compensation data to the 16°C interval format. The measured data can have any temperature points and the software will fit a curve through the measured points and calculate new PWM values in fixed temperatures using the curves. The procedure is explained in the Application Note AN1462, LP5520 RGB Backlight Driver Evaluation Kit. By using the evaluation software to convert the measurement results to EEPROM memory map the user does not need to care about the details of the EEPROM structure. Typical color coordinate and intensity stability over temperature are shown in the following two graphs. 20186134 9 www.national.com LP5520 RGB Driver Functionality LP5520 Compensated Color Coordinates vs. Temperature Compensated Blue LED Intensity vs. Temperature 20186141 20186142 CALIBRATION MEMORY The 1 kbit calibration EEPROM memory is organized as 128 x 8 bits. It stores the 12-bit calibration PWM values for each output at 16°C intervals. 10 temperature points are used to cover the range from –40 to 120°C. The temperature or light sensor calibration data, self heating factor and LED currents are also stored in the memory. The memory contents and detailed memory map are shown in the following tables. The EEPROM contents Data www.national.com Length Total bits 10 PWM values for red 12 120 10 coefficients for red between the points 8 80 10 PWM values for green 12 120 10 coefficients for green between the points 8 80 10 PWM values for blue 12 120 10 coefficients for blue between the points 8 80 0°C reading for temperature sensor 12 12 Coefficient for temperature sensor 12 12 Maximum self-heating (100% red PWM) 8 8 Default current for ROUT 8 8 Default current for GOUT 8 8 Default current for BOUT 8 8 Free memory for user data 8 368 10 LP5520 EEPROM memory map Address Bits [7:4] Bits [3:0] Definition 00 RB0[7:0] 01 RB1[7:0] 02 RB2[7:0] 03 RB3[7:0] +8...+23 04 RB4[7:0] +24...+39 05 RB5[7:0] +40...+55 06 RB6[7:0] +56...+71 07 RB7[7:0] +72...+87 08 RB8[7:0] +88...+103 09 RB9[7:0] From +104 0a GB0[7:0] 0b GB1[7:0] 0c GB2[7:0] 0d GB3[7:0] +8...+23 0e GB4[7:0] +24...+39 0f GB5[7:0] +40...+55 10 GB6[7:0] +56...+71 11 GB7[7:0] +72...+87 12 GB8[7:0] +88...+103 13 GB9[7:0] 14 BB0[7:0] 15 BB1[7:0] 16 BB2[7:0] 17 BB3[7:0] +8...+23 18 BB4[7:0] +24...+39 19 BB5[7:0] +40...+55 1a BB6[7:0] +56...+71 1b BB7[7:0] +72...+87 1c BB8[7:0] +88...+103 1d BB9[7:0] 1e LM20K[7:0] 1f LM20B[7:0] Base PWM-value for red (8 LSB bits) -40...-25 -24...-9 -8...+7 Base PWM-value for green (8 LSB bits) -40...-25 -24...-9 -8...+7 From +104 Base PWM-value for blue (8 LSB bits) -40...-25 -24...-9 -8...+7 From +104 Scaling values for LM20 sensor K B 20 Not used ... 3f 40 RC0[7:0] Coefficient PWM-value for red -40...-25 41 RC1[7:0] 42 RC2[7:0] -8...+7 43 RC3[7:0] +8...+23 44 RC4[7:0] +24...+39 45 RC5[7:0] +40...+55 46 RC6[7:0] +56...+71 47 RC7[7:0] +72...+87 48 RC8[7:0] +88...+103 49 RC9[7:0] From +104 -24...-9 11 www.national.com LP5520 Address Bits [7:4] Bits [3:0] Definition 4a GC0[7:0] 4b GC1[7:0] -24...-9 4c GC2[7:0] -8...+7 4d GC3[7:0] +8...+23 4e GC4[7:0] +24...+39 4f GC5[7:0] +40...+55 50 GC6[7:0] +56...+71 51 GC7[7:0] +72...+87 52 GC8[7:0] +88...+103 53 GC9[7:0] From +104 54 BC0[7:0] 55 BC1[7:0] -24...-9 56 BC2[7:0] -8...+7 57 BC3[7:0] +8...+23 58 BC4[7:0] +24...+39 59 BC5[7:0] +40...+55 5a BC6[7:0] +56...+71 5b BC7[7:0] +72...+87 5c BC8[7:0] +88...+103 5d BC9[7:0] 5e SHF[7:0] Coefficient PWM-value for green Coefficient PWM-value for blue -40...-25 -40...-25 From +104 Self heating factor 5f RED_CUR Red LED current 60 GREEN_CUR Green LED current 61 BLUE_CUR Blue LED current 62 Not used ... 6f 70 LM20B[11:8] LM20K[11:8] Scaling values for LM20 sensor 71 BB9[11:8] BB8[11:8] Base PWM-value for blue (high bits) 72 BB7[11:8] BB6[11:8] 73 BB5[11:8] BB4[11:8] 74 BB3[11:8] BB2[11:8] 75 BB1[11:8] BB0[11:8] 76 GB9[11:8] GB8[11:8] 77 GB7[11:8] GB6[11:8] 78 GB5[11:8] GB4[11:8] 79 GB3[11:8] GB2[11:8] 7a GB1[11:8] GB0[11:8] 7b RB9[11:8] RB8[11:8] 7c RB7[11:8] RB6[11:8] 7d RB5[11:8] RB4[11:8] 7e RB3[11:8] RB2[11:8] 7f RB1[11:8] RB0[11:8] www.national.com Base PWM-value for green (high bits) Base PWM-value for red (high bits) 12 <ee_page[1:0]> (bits1-0) 00 page0 (00H-1FH) 01 page1 (20H-3FH) 10 page2 (40H-5FH) 11 page3 (60H-7FH) Actually the EEPROM consist of two type of memory, 128 x 8 EEPROM (Non Volatile Memory) and 128 x 8 SRAM (Synchronous Random Access Memory). The EEPROM is used to store calibrated RGB control values when the system is powered off. SRAM is used as working memory during operation. 20186116 EEPROM content is copied into SRAM always when the chip is taken from stand-by mode to active mode. Copying to SRAM can also be made during operation by writing the <ee_read> bit high and low in the EEPROM control (0DH) register. For reading the data from the SRAM, the page number must be set with <ee_page[1:0]> bits and the page read from addresses 40H – 5FH. The EEPROM must be erased before programming. The erase command will erase one page at time, which must be selected with <ee_page[1:0]> bits. This operation starts after setting and resetting <ee_erase> and takes about 100 ms after rising <ee_erase> bit. During erasing <ee_prog> bit of the EEPROM_CONTROL register is low. Corresponding SRAM area will be erased with this operation also. <ee_erase> and <ee_prog> can be set only one command at a time (erase or program). During programming the content of SRAM is copied to EEPROM. EEPROM programming cycle has two steps. At first, write the whole content of the SRAM, all 4 pages. The whole page can be written during one SPI/I2C cycle in the auto-increment mode. Second step is programming the EEPROM. This operation starts after writing <ee_prog> high and back low and takes about 100 ms after rising <ee_prog> bit. During programming <ee_prog> bit of the EEPROM_CONTROL register is low. For EEPROM erasing and programming the chip has to be in active mode (<NSTBY> high), the boost must be off (<in_boost> low) and the boost voltage set to 18V (boost output register value 12H). 13 www.national.com LP5520 The EEPROM data can be read, written and erased through the serial interface. The boost converter is used to generate the write and erase voltage for the memory. All operations are done in page mode. The page address has to be written in the EEPROM_control register before access to the EEPROM. Incremental access can be used both in I2C and SPI modes to speed up access. During EEPROM access the <rgb_auto> control bit in rgb control register must be low. The EEPROM has 4 pages; only one page at time can be mirrored at the register map. For getting access to page, the number of page must be set by <ee_page[1:0]> bits in the EEPROM_control register(0DH). The page register address range is from 40H to 5FH. LP5520 fines a multiplier for the 12-bit PWM value obtained from the memory according to the following table. LED BRIGHTNESS CONTROL The LED brightness is defined by two factors, the current through the LED and the PWM duty cycle. The constant current outputs ROUT, GOUT and BOUT can be independently set to sink between 0 and 60 mA. The 8-bit current control has 255 levels and the step size is 235 µA. In manual mode the current is defined with the current control (R/G/B) registers (01H, 02H and 03H). In automatic mode the current settings come from the EEPROM. The PWM control has 12-bit resolution, which means 4095 steps. The minimum pulse width is 200 ns and the frequency can be set to either 1.2 kHz or 19.2 kHz. The duty cycle range is from 0 to 100% (0 to 4095). The output PWM value is obtained by multiplication of three factors. The first factor is the temperature-based value from the EEPROM. The second factor is the correction register setting, which is independent for each color. The third factor is the brightness register setting, which is common to all colors. The temperature based PWM values are stored in the EEPROM at 16°C intervals starting from -40°C and ending to 120° C. PWM values for the temperatures between the stored points are interpolated. LED brightness has 3-bit logarithmic control. The control bits are in the pwm_brightness (04H) register. The 3-bit value de- Control byte <bri[2:0]> Multiplier Intensity % 0 0.008 0.8 1 0.016 1.6 2 0.031 3.1 3 0.063 6.3 4 0.125 12.5 5 0.250 25.0 6 0.500 50.0 7 1.000 100.0 PWM Brightness register control The brightness correction can be used for aging compensation or other fine-tuning. There is an 8-bit correction register for each output. The PWM value obtained from the memory is multiplied by the correction value. The default correction value is 1. Correction range is from 0 to 2 and the lsb is 0.78% (1/128). 20186155 LED control principle, shown complete only for red channel LED PWM CONTROL The PWM frequency can be selected of two alternatives, slow and fast, with the control bit <pwm_fast>. The slow frequency is 1.2 kHz. In the fast mode the PWM frequency is multiplied by 16 and the frequency is 19.2 kHz. Fast mode is the default mode after reset. The single pulse in normal PWM is split in 16 narrow pulses in fast PWM. Higher frequency helps eliminate possible noise from the ceramic capacitors and it also reduces the ripple in the boost voltage. Minimum pulse length is 200 ns in both modes. www.national.com The PWM pulses of each output do not start simultaneously in order to avoid high current spike. Red starts in the beginning of the PWM cycle, Green is symmetric with the cycle center and Blue ends in the end of the cycle. For PWM values less than 33% for each output, the output currents are completely non-overlapping. With higher PWM values the overlapping increases. 14 LP5520 20186117 Pulse positions in the PWM cycle trigger pulse width in the PWM inputs is 1 µs. There is no limitation on the maximum width of the pulse as long as it is shorter than the whole sequence. SEQUENTIAL MODE Completely non-overlapping timing can be obtained by using the sequential mode as shown in the graph below. The timing is defined with external PWM control inputs. The minimum 20186118 Non-overlapping external synchronized sequential mode In sequential mode the PWM cycle is synchronized to trigger pulses and the amount of PWM pulses per trigger can be defined to 2, 3 or 4 using the <seq_mode0> and <seq_mode1> control bits. This makes possible to use sequence lengths of about 5 ms, 7.5 ms or 10 ms. Fast PWM can be used in sequential mode, but the frame timing is as with normal PWM. The PWM timing and synchronization timing originate from different clock sources. Some margin should be allowed for clock tolerances. This margin shows as a dead time in the waveform graph. Some dead time should be allowed so that no PWM pulse will be clipped. Clipping would distort the intensity balance between the LEDs. The dead time will cause some intensity reduction, but will assure the current balance. 15 www.national.com LP5520 PWM mode defined by <seq_mode1> and <seq_mode2> control bits of rgb_control (00H) register: <seq_mode1> (bit 7) <seq_mode0> (bit 6) 0 0 Normal mode 0 1 Sequential mode with 2 PWM pulses per trigger 1 0 Sequential mode with 3 PWM pulses per trigger 1 1 Sequential mode with 4 PWM pulses per trigger Mode PWM control inputs PWMR, PWMG and PWMB can be used as external output enables in normal and automatic mode. In the sequential mode these inputs are the trigger inputs for respective outputs. CURRENT CONTROL OF THE LEDS LP5520 has separate 8-bit current control for each LED output. In manual mode the current for red LED is controlled with current_control_r (01H) register, for green LED with current_control_g (02H) and for blue LED with current_control_b (03H). Output current can be calculated with formula: current (mA) = code x 0.235, for example 20 mA current is obtained with code 85 (55H). In automatic and stand-alone modes the LED current values programmed in EEPROM are used, and the current control registers have no effect. There are two ways to change the default current if needed. The defaults can be changed permanently by programming new values to the EEPROM. The other option is to make a temporary change by writing new current values in SRAM. Since this is not normally needed, it is only described in the Calibration Application Note AN1459. FADE IN / FADE OUT LP5520 has an automatic fade in and out for the LED outputs. Fading makes the transitions smooth in on/off switching or when brightness is changed. It is not applied for the changes caused by the compensation algorithm. The fade can be turned on and off using the <en_fade> bit in the rgb_control (00H) register. The fade time is constant 520 ms and it does not depend on how big the brightness change is. The white balance is maintained during fading. Fading is off in the Stand-alone mode. <en_fade>(bit 5) OUTPUT ENABLES ROUT, GOUT and BOUT output activity is controlled with 3 enable bits of the rgb_control (00H) register: <en_b> (bit 2) 0 Blue LED output BOUT disabled 1 Blue LED output BOUT enabled <en_g> (bit 1) 0 Green LED output GOUT disabled 1 Green LED output GOUT enabled <en_r> (bit 0) 0 Red LED output ROUT disabled 1 Red LED output ROUT enabled www.national.com 0 Automatic fade disabled 1 Automatic fade enabled Fading only works in automatic mode. The LED current registers should be written to 0 for proper Fade operation. When the LEDs are turned on with Fading, it is best to set the brightness first and then enable the outputs and automatic mode. The LEDs can be turned off then by turning off the automatic mode (write rgb_auto to 0). 16 Symbol Parameter ILEAKAGE ROUT, GOUT and BOUT pin leakage current Condition Min Typ Max Units 0.1 1 µA IMAX Maximum Sink Current Outputs ROUT, GOUT and BOUT Control = 255 (FFH) 60 mA IR Current accuracy of ROUT, GOUT and BOUT Output current set to 20 mA 19 -5 20 21 +5 mA % Output current set to 60 mA 54 -10 60 66 +10 mA % ±0.2 ±2 % IMATCH Matching (Note 10) Between ROUT, GOUT and BOUT at 20 mA current tPWM PWM cycle time Accuracy proportional to internal clock frequency 820 µs fRGB RGB switching frequency <pwm_fast> = 0 1.22 kHz <pwm_fast> = 1 19.52 kHz VSAT Saturation voltage (Note 11) I(LED) = 60 mA 550 mV fMAX External PWM maximum frequency I(LED) = 60 mA 1 MHz Note 10: Matching is the maximum difference from the average when all outputs are set to same current. Note 11: Saturation voltage is defined as the voltage when the LED current has dropped 10% from the value measured at 2V. RGB DRIVER TYPICAL PERFORMANCE CHARACTERISTICS VSAT vs ILED 20186110 17 www.national.com LP5520 RGB DRIVER ELECTRICAL CHARACTERISTICS (ROUT, GOUT, BOUT Outputs) LP5520 Temperature and Light Measurement LP5520 has a 12-bit Analog-to-Digital Converter for the measurements. The ADC has two inputs. S1_IN input is intended for the LM20 temperature sensor and S2_IN input for light measurement or any DC voltage measurement. The conversion results are filtered with average filter for 134 ms. The <adc_ch> bit in the Control register selects, which conversion result can be read out from the registers ADC_hi_byte and ADC_low_byte. The ADC_hi_byte has to be read first. adc_ch(bit5) comp_sel(bit4) The <comp_ch> bit selects, which input is used for compensation. The ADC uses the LDO voltage 2.8V as the reference voltage. The input signal range is 0 – 2.8V and the inputs are buffered on the chip. If S2_IN is used for light measurement using TDK optical sensor BCS2015G1 as shown in the Block Diagram on page 5, the measurement range is from 10 to 20.000 lux when using 100k resistor. 0 S1 input can be read 1 S2 input can be read 0 S1 input is used for compensation 1 S2 input is used for compensation 20186119 www.national.com 18 The LP5520 Boost DC/DC Converter generates a 5 to 20V supply voltage for the LEDs from single Li-Ion battery (2.9 to 4.5V). The output voltage is controlled with four bits in 18 steps. In adaptive mode the output voltage is automatically adjusted so that the LED drivers have enough voltage for <en_autoload> (bit 3) <vout_auto> (bit 2) <en_boost> (bit 1) <nstby> (bit 0) proper operation. The converter is a magnetic switching PWM mode DC/DC converter with a current limit. Switching frequency is 1 MHz. Boost converter options are controlled with few bits of Control (06H) register. 0 Internal boost converter loader off 1 Internal boost converter loader on 0 Manual boost output adjustment 1 Adaptive boost output adjustment 0 Boost converter standby mode 1 Boost converter active mode 0 LP5520 standby mode 1 LP5520 active mode The LP5520 Boost Converter uses pulse-skipping elimination to stabilize the noise spectrum. Even with light load or no load a minimum length current pulse is fed to the inductor. An active load is used to remove the excess charge from the output capacitor at very light loads. Active load can be disabled with the <en_autoload> bit. Disabling active load will increase slightly the efficiency at light loads, but the downside is that pulse skipping will occur. The Boost Converter should be stopped when there is no load to minimize the current consumption. The topology of the magnetic boost converter is called CPM control, current programmed mode, where the inductor current is measured and controlled with the feedback. The user can program the output voltage of the boost converter. The output voltage control changes the resistor divider in the feedback loop. The following figure shows the boost topology with the protection circuitry. Four different protection schemes are implemented: 1. 2. 3. 4. Over voltage protection, limits the maximum output voltage — Keeps the output below breakdown voltage. — Prevents boost operation if battery voltage is much higher than desired output. Over current protection, limits the maximum inductor current — Voltage over switching NMOS is monitored; too high voltages turn the switch off. Feedback break protection. Prevents uncontrolled operation if FB pin gets disconnected. Duty cycle limiting, done with digital control. 20186120 Boost Converter Topology 19 www.national.com LP5520 Magnetic High Voltage Boost DC/DC Converter LP5520 MAGNETIC BOOST DC/DC CONVERTER ELECTRICAL CHARACTERISTICS Symbol Parameter Conditions ILOAD Maximum 2.9V = VIN Continuous Load VOUT = 20V Current VOUT Output Voltage Accuracy (FB Pin) 2.9V ≤ VIN ≤ 5.5V VOUT = 20V RDSON Switch ON Resistance ISW = 0.5A fPWM Frequency Accuracy tPULSE Switch Pulse Minimum Width tSTARTUP Startup Time IMAX SW Pin Current Limit Min 1.7 +5 −6 −9 no load Dec 5 5.0V 00110 6 6.0V 00111 7 7.0V ... ... ... 01100 12 12.0V 01101 13 13.0V 01110 14 14.0V ... ... ... 10010 18 18.0V 10011 19 19.0V 10100 20 20.0V ±3 % +6 +9 % 50 ns 20 ms 1100 mA If register value is lower than 5, then value of 5 is used internally. If register value is higher than 20, then value of 20 is used internally. ADAPTIVE OUTPUT VOLTAGE CONTROL When automatic boost voltage control is selected using the <vout_auto> bit in Control (06H) register, the user defined boost output voltage is ignored. The boost output voltage is adjusted for sufficient operating headroom by monitoring all enabled LED driver outputs. The boosted voltage is adjusted so that the lowest driver voltage is between 0.85 and 1.35V when the LED output currents are below 30 mA and to 1.0 – 1.5V when any LED current is above 30 mA. The output voltage range is from 5.0 to 20V in adaptive mode. The adaptive voltage control helps saving energy by always setting the boost voltage to minimum sufficient value. It eliminates the need for extra voltage margins due to LED forward voltage variation or temperature variation. With very small brightness settings, when the PWM pulses in LED outputs are very narrow, the adaptive voltage setting will give higher than necessary boost voltage. This does not harm the overall efficiency, since this happens only when the power used is very small. After reset the adaptive control is on by default. In stand-alone mode the adaptive output voltage is always used. Boost Output Voltage (typical) Bin Units Ω 0.3 00101 www.national.com Max mA -1.7 -5 BOOST CONTROL User can set the Boost Converter to STANDBY mode by writing the register bit <en_boost> low. When <en_boost> is written high, the converter starts for 50 ms in low current PWM mode and then goes to normal PWM mode. User can control the boost output voltage by boost output boost_output (05H) register. Boost Output [7:0] Register 0DH Typ 70 20 LP5520 Boost Converter Typical Performance Characteristics VIN = 3.6V, VOUT = 15.0V if not otherwise stated Boost Converter Efficiency Boost Typical Waveforms at 60 mA Load 20186121 20186122 Boost Max. Output Voltage vs. Current Battery Current vs. Voltage 20186124 20186123 Adaptive Output Voltage Operation Autoload Effect on Input Current, No Load 20186129 20186128 21 www.national.com LP5520 Logic Interface Characteristics Symbol Parameter Conditions Min Typ Max Units 0.2 × VDDIO V Logic Inputs SS, SI/A0, SCK/SCL, IFSEL, NRST, PWMR, PWMG, PWMB and BRC VIL Input Low Level VIH Input High Level II Logic Input Current fSCK/SLC Clock Frequency 0.8 × VDDIO V −1.0 µA 1.0 I2C Mode 0.4 SPI Mode VDDIO > 1.8V 13 SPI Mode 1.65V < VDDIO < 1.8V 5 MHz Logic input NRST VIL Input Low Level VIH Input High Level 1.2 II Logic Input Current -1.0 tNRST Reset Pulse Width 10 V 0.5 V µA 1.0 µs Logic Output SO VOL VOH IL Output Low Level Output High Level Output Leakage Current ISO = 3 mA VDDIO > 1.8V 0.3 0.5 V ISO = 2 mA 1.65V < VDDIO < 1.8V 0.3 0.5 V ISO = -3 mA VDDIO > 1.8V VDDIO − 0.5 VDDIO − 0.3 V ISO = -2 mA 1.65V < VDDIO < 1.8V VDDIO − 0.5 VDDIO − 0.3 V VSO = 2.8V 1.0 µA 0.5 V Logic Output SDA VOL Output Low Level ISDA = 3 mA 0.3 and Read Cycles. One cycle consists of 7 Address bits, 1 Read/Write (RW) bit and 8 Data bits. RW bit high state defines a Write Cycle and low defines a Read Cycle. SO output is normally in high-impedance state and it is active only when Data is sent out during a Read Cycle. The Address and Data are transmitted MSB first. The Slave Select signal SS must be low during the Cycle transmission. SS resets the interface when high and it has to be taken high between successive Cycles. Data is clocked in on the rising edge of the SCK clock signal, while data is clocked out on the falling edge of SCK. Control Interface LP5520 supports two different interface modes: • SPI interface (4 wire, serial) • I2C compatible interface (2 wire, serial) User can define the serial interface by IF_SEL pin. IF_SEL = 0 selects the I2C mode. SPI Interface LP5520 is compatible with SPI serial bus specification and it operates as a slave. The transmission consists of 16-bit Write 20186130 SPI Write Cycle www.national.com 22 LP5520 20186131 SPI Read Cycle 20186132 SPI Timing Diagram SPI TIMING PARAMETERS VDDA = VDDD = VDD_IO = 2.775V Symbol Parameter Limit Min Units Max 1 Cycle Time 70 ns 2 Enable Lead Time 35 ns 3 Enable Lag Time 35 ns 4 Clock Low Time 35 ns 5 Clock High Time 35 ns 6 Data Setup Time 0 ns 7 Data Hold Time 25 8 Data Access Time 30 ns 9 Disable Time 20 ns 40 ns 10 Data Valid 11 Data Hold Time 0 ns ns NOTE: Data guaranteed by design. SPI INCREMENTAL ADDRESSING LP5520 supports incremental addressing for memory read and write. 23 www.national.com LP5520 I2C Compatible Interface I2C SIGNALS The serial interface is in I2C mode when IF_SEL = 0. The SCL pin is used for the I2C clock and the SDA pin is used for bidirectional data transfer. Both these signals need a pull-up resistor according to I2C specification. The values of the pullup resistors are determined by the capacitance of the bus (typical resistance is 1.8k). Signal timing specifications are shown in table I2C Timing Parameters. 20186150 I2C Start and Stop Conditions I2C DATA VALIDITY The data on SDA line must be stable during the HIGH period of the clock signal (SCL). In other words, state of the data line can only be changed when CLK is LOW. TRANSFERRING DATA Every byte put on the SDA line must be eight bits long, with the most significant bit (MSB) being transferred first. Each byte of data has to be followed by an acknowledge bit. The acknowledge related clock pulse is generated by the master. The transmitter releases the SDA line (HIGH) during the acknowledge clock pulse. The receiver must pull down the SDA line during the 9th clock pulse, signifying an acknowledge. A receiver which has been addressed must generate an acknowledge after each byte has been received. After the START condition, the I2C master sends a chip address. This address is seven bits long followed by an eighth bit which is a data direction bit (R/W). The LP5520 address is 20h when SI=0 and 21h when SI=1. For the eighth bit, a “0” indicates a WRITE and a “1” indicates a READ. The second byte selects the register to which the data will be written. The third byte contains data to write to the selected register. 20186149 I2C Signals: Data Validity I2C START AND STOP CONDITIONS START and STOP bits classify the beginning and the end of the I2C session. START condition is defined as SDA signal transitioning from HIGH to LOW while SCL line is HIGH. STOP condition is defined as the SDA transitioning from LOW to HIGH while SCL is HIGH. The I2C master always generates START and STOP bits. The I2C bus is considered to be busy after START condition and free after STOP condition. During data transmission, I2C master can generate repeated START conditions. First START and repeated START conditions are equivalent, function-wise. 20186151 I2C Chip Address 20186136 w = write (SDA = “0”) r = read (SDA = “1”) ack = acknowledge (SDA pulled down by either master or slave) rs = repeated start id = 7-bit chip address, 20h when SI=0 and 21h when SI=1 for LP5520. I2C Write Cycle www.national.com 24 LP5520 When a READ function is to be accomplished, a WRITE function must precede the READ function, as shown in the I2C Read Cycle waveform. 20186137 I2C Read Cycle 20186154 I2C Timing Diagram I2C TIMING PARAMETERS (VDD1,2 = 3.0 to 4.5V, VDDIO = 1.8V to VDD1,2) Symbol Limit Parameter Min Max Units 1 Hold Time (repeated) START Condition 0.6 µs 2 Clock Low Time 1.3 µs 3 Clock High Time 600 ns 4 Setup Time for a Repeated START Condition 600 ns 5 Data Hold Time (Output direction, delay generated by LP5520) 300 900 ns 5 Data Hold Time (Input direction, delay generated by Master) 0 900 ns 6 Data Setup Time 7 Rise Time of SDA and SCL 20 + 0.1Cb 300 ns 8 Fall Time of SDA and SCL 15 + 0.1Cb 300 ns 100 9 Set-up Time for STOP condition 600 10 Bus Free Time between a STOP and a START Condition 1.3 Cb Capacitive Load for Each Bus Line 10 ns ns µs 200 pF NOTE: Data guaranteed by design 25 www.national.com LP5520 Recommended External Components load regulation to suffer. A schottky diode with low parasitic capacitance helps in reducing EMI noise. Examples of suitable diodes are: Central Semiconductor CMMSH1-40 and Infineon BAS52-02V. OUTPUT CAPACITOR: COUT The output capacitor COUT directly affects the magnitude of the output ripple voltage. In general, the higher the value of COUT, the lower the output ripple magnitude. Multilayer ceramic capacitors with low ESR are the best choice. Capacitor voltage rating must be sufficient, 25V or greater is recommended. Examples of suitable capacitors are: TDK C3216X5R1E475K, Panasonic ECJ3YB1E475K and ECJ4YB1E475K. Some ceramic capacitors, especially those in small packages, exhibit a strong capacitance reduction with the increased applied voltage (DC bias effect). The capacitance value can fall below half of the nominal capacitance. Too low output capacitance can make the boost converter unstable. Output capacitor value reduction due to DC bias should be less than 70% at 20V (minimum 3 µF of real capacitance remaining). EMI FILTER COMPONENTS: CSW, RSW, LSW and CHF EMI filter (RSW, CSW and LSW ) on the SW pin may be needed to slow down the fast switching edges and reduce ringing. These components should be as near as possible to the SW pin to ensure reliable operation. High frequency capacitor (CSW) in the boost output helps in suppressing the high frequency noise from the switcher. 50V or greater voltage rating is recommended for the capacitors. The ferrite bead DC resistance should be less than 0.1Ω and current rating 1A or above. The impedance at 100 MHz should be 30 – 300Ω. Examples of suitable types are TDK MPZ1608S101A and Taiyo-Yuden FBMH 1608HM600-T. INDUCTOR: L1 A 4.7 µH shielded inductor is suggested for LP5520 boost converter. The inductor should have a saturation current rating higher than the peak current it will experience during circuit operation (0.5 – 1.0A depending on the output current). Less than 500 mΩ ESR is suggested for high efficiency. Open core inductors cause flux linkage with circuit components and interfere with the normal operation of the circuit. This should be avoided. For high efficiency, choose an inductor with a high frequency core material such as ferrite to reduce the core losses. To minimize radiated noise, use a toroid, pot core or shielded core inductor. The inductor should be connected to the SW pin as close to the IC as possible. Examples of suitable inductors are: TDK VLF3010AT-4R7MR70 and Coilcraft LPS3010-472NL. INPUT CAPACITOR: CIN The input capacitor CIN directly affects the magnitude of the input ripple voltage and to a lesser degree the VOUT ripple. A higher value CIN will give a lower VIN ripple. OUTPUT DIODE: DOUT A schottky diode should be used for the output diode. To maintain high efficiency the average current rating of the schottky diode should be greater than the peak inductor current (1A). Schottky diodes with a low forward drop and fast switching speeds are ideal for increasing efficiency in portable applications. Choose a reverse breakdown voltage of the schottky diode significantly larger (~30V) than the output voltage. Do not use ordinary rectifier diodes, since slow switching speeds and long recovery times cause the efficiency and the LIST OF RECOMMENDED EXTERNAL COMPONENTS Symbol Value Unit CVDDA Symbol Explanation C between VDDA and GND 100 nF Ceramic, X7R / X5R CVDDD C between VDDD and GND 100 nF Ceramic, X7R, X5R CVLDO C between VLDO and GND CVDDIO C between VDDIO and GND C between FB and GND Type 1 µF Ceramic, X7R / X5R 100 nF Ceramic, X7R / X5R 2 x 4.7 µF Ceramic, X7R / X5R, tolerance ±10%, DC bias effect ~ –30% at 20V COUT CIN C between battery voltage and GND 10 µF Ceramic, X7R / X5R L1 L between SW and VBAT 4.7 µH Shielded, low ESR, ISAT 0.5A 0. 3 - 0.5 V Schottky diode, reverse voltage 30V, repetitive peak current 0.5A 330 pF Ceramic, X7R / X5R, 50V D1 Rectifying Diode (Vf @ maxload) CSW Optional C in EMI filter RSW Optional R in EMI filter 3.9 Ω ±1% CHF Optional high frequency output C 33 - 100 pF Ceramic, X7R, X5R, 50V LSW Ferrite bead in SW pin 30 - 300 Ω at 100 Mhz LEDs www.national.com User Defined 26 All registers will have their default value after power-on or reset. Default value for correction registers is 1000 0000 (multiplier = 1). Default value for adaptive voltage control and fast PWM is on. Default value for current set registers is 55H which will set the current to 20 mA. Default value for all other register bits is 0. Note, that in automatic compensation mode the LED currents are obtained from the EEPROM. Bits with r/o are read-only bits. ADR REG NAME D7 D6 D5 D4 D3 D2 D1 D0 DEFAULT 00H rgb control seq_ mode[1] seq_ mode[0] en_fade pwm_ fast rgb_auto en_b en_g en_r 0001 0000 01H current control (R) cc_r[7] cc_r[6] cc_r[5] cc_r[4] cc_r[3] cc_r[2] cc_r[1] cc_r[0] 0101 0101 02H current control (G) cc_g[7] cc_g[6] cc_g[5] cc_g[4] cc_g[3] cc_g[2] cc_g[1] cc_g[0] 0101 0101 03H current control (B) cc_b[7] cc_b[6] cc_b[5] cc_b[4] cc_b[3] cc_b[2] cc_b[1] cc_b[0] 0101 0101 04H pwm brightness brc_off bri2 bri1 bri0 0000 0000 05H boost output vprog[4] vprog[3] vprog[2] vprog[1] vprog[0] 0000 0000 06H control comp_ sel en_ autoload vout_ auto en_boost nstby 0000 0100 08H ADC_ hi_byte bit11 (r/o) bit10 (r/o) bit9 (r/o) bit8 (r/o) 09H ADC_ low_byte bit7 (r/o) bit6 (r/o) bit3 (r/o) bit2 (r/o) bit1 (r/o) bit0 (r/o) 0AH R correction corr_r[7] corr_r[6] corr_r[2] corr_r[1] corr_r[0] 1000 0000 0BH G correction corr_g[7] corr_g[6] corr_g[5] corr_g[4] corr_g[3] corr_g[2] corr_g[1] corr_g[0] 1000 0000 0CH B correction corr_b[7] corr_b[6] corr_b[5] corr_b[4] corr_b[3] corr_b[2] corr_b[1] corr_b[0] 1000 0000 0DH EEPROM Control ee_page [1] ee_page [0] 0000 0000 adc_ch ee_ready ee_erase (r/o) bit5 (r/o) bit4 (r/o) corr_r[5] corr_r[4] corr_r[3] ee_prog ee_read Register addresses from 40H to 5FH contain the EEPROM page. EEPROM access is described in the Calibration Memory chapter. 27 www.national.com LP5520 LP5520 Registers, Control Bits and Default Values LP5520 REGISTER BIT CONVENTIONS Each register is shown with a key indicating the accessibility of the each individual bit, and the initial condition: Register Bit Accessibility and Initial Condition Key Bit Accessibility rw Read/write r Read only –0, –1 Condition after POR rgb_control (00H) – RGB LEDs Control Register 7 6 5 4 3 2 1 0 seq_mode1 seq_mode0 en_fade pwm_fast rgb_auto en_b en_g en_r rw-0 rw-0 rw-0 rw-1 rw-0 rw-0 rw-0 rw-0 0 0 – overlapping PWM mode 0 1 – sequential mode with 2 PWM pulses 1 0 – sequential mode with 3 PWM pulses 1 1 – sequential mode with 4 PWM pulses seq_mode[1:0] Bits 6 - 7 en_fade Bit 5 0 – automatic fade disabled 1 – automatic fade enabled pwm_fast Bit 4 0 – normal PWM frequency 1.22 kHz 1 – high PWM frequency 19.52 kHz rgb_auto Bit 3 0 – automatic compensation disabled 1 – automatic compensation enabled en_b Bit 2 0 – blue LED output BOUT disabled 1 – blue LED output BOUT enabled en_g Bit 1 0 – green LED output GOUT disabled 1 – green LED output GOUT enabled en_r Bit 0 0 – red LED output ROUT disabled 1 – red LED output ROUT enabled current_control_R (01H) – Red LED Current Control Register 7 6 5 4 3 2 1 0 cc_r[7] cc_r[6] cc_r[5] cc_r[4] cc_r[3] cc_r[2] cc_r[1] cc_r[0] rw-0 rw-1 rw-0 rw-1 rw-0 rw-1 rw-0 rw-1 Adjustment cc_r[7:0] www.national.com Bits 7 - 0 cc_r[7:0] Typical driver current (mA) 0000 0000 0 0000 0001 0.234 0000 0010 0.468 0000 0011 0.702 ... ... 1111 1101 59.202 1111 1110 59.436 1111 1111 59.670 28 LP5520 current_control_G (02H) – Green LED Current Control Register 7 6 5 4 3 2 1 0 cc_g[7] cc_g[6] cc_g[5] cc_g[4] cc_g[3] cc_g[2] cc_g[1] cc_g[0] rw-0 rw-1 rw-0 rw-1 rw-0 rw-1 rw-0 rw-1 current_control_B (03H) – Blue LED Current Control Register 7 6 5 4 3 2 1 0 cc_b[7] cc_b[6] cc_b[5] cc_b[4] cc_b[3] cc_b[2] cc_b[1] cc_b[0] rw-0 rw-1 rw-0 rw-1 rw-0 rw-1 rw-0 rw-1 pwm_brightness (04H) – Brightness Control Register 7 r-0 6 5 r-0 4 r-0 rw-0 3 2 1 0 brc_off bri[2] bri[1] bri[0] r-0 rw-0 rw-0 rw-0 brc_off = 0 - stand-alone mode, brightness is defined with external BRC signal brc_off = 1 - brightness is defined with bri[2:0] brc_off bri[2:0] Bit 4 Bits 2-0 Control Multiplier Intensity % 0 0.008 0.8 1 0.016 1.6 10 0.031 3.1 11 0.063 6.3 100 0.125 12.5 101 0.250 25 110 0.500 50 111 1.000 100 29 www.national.com LP5520 boost_output (05H) – Boost Output Voltage Control Register 7 6 r-0 5 r-0 4 3 2 1 0 vprog[4] vprog[3] vprog[2] vprog[1] vprog[0] r-0 rw-0 rw-0 rw-0 rw-0 r-0 Adjustment Bits 4 - 0 vprog[4:0] vprog[4:0] Typical boost output voltage (V) 00101 5.0 00110 6.0 00111 7.0 01000 8.0 01001 9.0 01010 10.0 01011 11.0 01100 12.0 01101 13.0 01110 14.0 01111 15.0 10000 16.0 10001 17.0 10010 18.0 10011 19.0 10100 20.0 control (06H) – Control Register 7 r-0 6 5 4 3 2 1 0 adc_ch comp_sel en_autoload vout_auto en_boost nstby rw-0 rw-0 rw-0 rw-1 rw-0 rw-0 r-0 adc_ch Bit 5 0 – compensation depends from the external LM20 temperature sensor 1 – compensation depends from forward voltage of the red LED as temperature sensor comp_sel Bit 4 0 – compensation based on S1_IN input 1 – compensation based on S2_IN input en_autoload Bit 3 0 – internal boost converter loader off 1 – internal boost converter loader off vout_auto Bit 2 0 – manual boost output adjustment with boost_output register 1 – automatic adaptive boost output adjustment en_boost Bit 1 0 – boost converter disabled 1 – boost converter enabled nstby Bit 0 0 – LP5520 standby mode 1 – LP5520 active mode ADC_hi_byte (08H) – Analog Digital Converter Output, bits 8-11 7 r-0 www.national.com 6 r-0 5 r-0 4 r-0 30 3 2 1 0 adc[11] adc[10] adc[9] adc[8] r-0 r-0 r-0 r-0 7 6 5 4 3 2 1 0 adc[7] adc[6] adc[5] adc[4] adc[3] adc[2] adc[1] adc[0] r-0 r-0 r-0 r-0 r-0 r-0 r-0 r-0 r_correction (0AH) – Additional Brightness Correction Value Register for Red LED 7 6 5 4 3 2 1 0 corr_r[7] corr_r[6] corr_r[5] corr_r[4] corr_r[3] corr_r[2] corr_r[1] corr_r[0] rw-1 rw-0 rw-0 rw-0 rw-0 rw-0 rw-0 rw-0 Correction corr_r[7:0] corr_r[7:0] Multiplier 0000 0000 0 0000 0001 0.0078 0000 0010 0.0156 Bits 7-0 ... ... 1000 0000 1.000 ... ... 1111 1101 1.991 1111 1110 1.999 1111 1111 2.000 g_correction (0BH) – Additional Brightness Correction Value Register for Green LED 7 6 5 4 3 2 1 0 corr_g[7] corr_g[6] corr_g[5] corr_g[4] corr_g[3] corr_g[2] corr_g[1] corr_g[0] rw-1 rw-0 rw-0 rw-0 rw-0 rw-0 rw-0 rw-0 b_correction (0CH) – Additional Brightness Correction Value Register for Blue LED 7 6 5 4 3 2 1 0 corr_b[7] corr_b[6] corr_b[5] corr_b[4] corr_b[3] corr_b[2] corr_b[1] corr_b[0] rw-1 rw-0 rw-0 rw-0 rw-0 rw-0 rw-0 rw-0 3 2 EEPROM_control (0DH) – EEPROM Control Register 7 6 5 4 ee_ready ee_erase ee_prog ee_read r-1 rw-0 rw-0 r-0 r-0 ee_ready Bit 7 EEPROM operations ready bit (read only) ee_erase Bit 6 Start bit for erasing sequence ee_prog Bit 5 Start bit for programming sequence Bit 4 Read EEPROM data to SRAM ee_read Bits 1-0 ee_page[1:0] r-0 1 0 ee_page[1] ee_page[0] rw-0 rw-0 ee_page[1] ee_page[0] page 0 0 0 00H-1FH (0-31) 0 1 1 20H-3FH (32-63) 1 0 2 40H-5FH (64-95) 1 1 4 60H-7FH (96-127) 31 EEPROM addresses www.national.com LP5520 ADC_low_byte (09H) – Analog Digital Converter Output, bits 0-7 LP5520 Physical Dimensions inches (millimeters) unless otherwise noted The dimension for X1 ,X2 and X3 are as given: — X1 = 2.77 mm ± 0.03 mm — X2 = 2.59 mm ± 0.03 mm — X3 = 0.6 mm ± 0.075 mm microSMD-25 Package: 2.77 x 2.59 x 0.60 mm NS Package Number TLA25EMA www.national.com 32 LP5520 Notes 33 www.national.com LP5520 RGB Backlight LED Driver Notes THE CONTENTS OF THIS DOCUMENT ARE PROVIDED IN CONNECTION WITH NATIONAL SEMICONDUCTOR CORPORATION (“NATIONAL”) PRODUCTS. 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