Sample & Buy Product Folder Support & Community Tools & Software Technical Documents LM3530 SNVS606L – JUNE 2009 – REVISED DECEMBER 2014 LM3530 High-Efficiency White-LED Driver with Programmable Ambient Light Sensing Capability and I2C-Compatible Interface 1 Features 3 Description • • • • The LM3530 current mode boost converter supplies the power and controls the current in up to 11 series white LEDs. The 839-mA current limit and 2.7-V to 5.5-V input voltage range make the device a versatile backlight power source ideal for operation in portable applications. 1 • • • • • • • • Drives up to 11 LEDs in series 1000:1 Dimming Ratio 90% Efficient Programmable Dual Ambient Light Sensor Inputs with Internal ALS Voltage Setting Resistors I2C Programmable Logarithmic or Linear Brightness Control External PWM Input for Simple Brightness Adjustment True Shutdown Isolation for LEDs and Ambient Light Sensors Internal Soft-Start Limits Inrush Current Wide 2.7-V to 5.5-V Input Voltage Range 40-V and 25-V Overvoltage Protection Options 500-kHz Fixed Frequency Operation 839-mA Peak Current Limit The LED current is adjustable from 0 mA to 29.5 mA via an I2C-compatible interface. The 127 different current steps and 8 different maximum LED current levels give over 1000 programmable LED current levels. Additionally, PWM brightness control is possible through an external logic level input. The device also features two Ambient Light Sensor inputs. These are designed to monitor analog output ambient light sensors and provide programmable adjustment of the LED current with changes in ambient light. Each ambient light sensor input has independently programmable internal voltage setting resistors which can be made high impedance to reduce power during shutdown. The 500-kHz switching frequency allows for high converter efficiency over a wide output voltage range accommodating from 2 to 11 series LEDs. Finally, the support of Content Adjusted Backlighting maximizes battery life while maintaining display image quality. 2 Applications • • • Smartphone LCD Backlighting Personal Navigation LCD Backlighting 2 to 11 Series White-LED Backlit Display Power Source space The LM3530 operates over the −40°C to 85°C temperature range. Device Information(1) PART NUMBER LM3530 PACKAGE DSBGA (12) BODY SIZE (MAX) 1.64 mm x 1.24 mm (1) For all available packages, see the orderable addendum at the end of the datasheet. Simplified Schematic L D1 Up to 40V 2.7V to 5.5V C OUT VLOGIC 10 k: SW IN 10 k: 10 k: 10 k: C IN LM3530 SCL OVP SDA HWEN INT PWM ILED VIN Ambient Light Sensor VIN ALS1 ALS2 Ambient Light Sensor GND 1 An IMPORTANT NOTICE at the end of this data sheet addresses availability, warranty, changes, use in safety-critical applications, intellectual property matters and other important disclaimers. PRODUCTION DATA. LM3530 SNVS606L – JUNE 2009 – REVISED DECEMBER 2014 www.ti.com Table of Contents 1 2 3 4 5 6 7 8 Features .................................................................. Applications ........................................................... Description ............................................................. Revision History..................................................... I2C Device Options ................................................ Pin Configuration and Functions ......................... Specifications......................................................... 1 1 1 2 3 3 4 7.1 7.2 7.3 7.4 7.5 7.6 7.7 7.8 4 4 4 4 5 6 6 7 Absolute Maximum Ratings ...................................... ESD Ratings.............................................................. Recommended Operating Conditions....................... Thermal Information .................................................. Electrical Characteristics .......................................... I2C-Compatible Timing Requirements (SCL, SDA) .. Simple Interface Timing ............................................ Typical Characteristics .............................................. Detailed Description ............................................ 11 8.1 Overview ................................................................. 11 8.2 Functional Block Diagram ....................................... 11 8.3 8.4 8.5 8.6 9 Feature Description................................................. Device Functional Modes........................................ Programming .......................................................... Register Maps ......................................................... 12 26 27 28 Application and Implementation ........................ 34 9.1 Application Information............................................ 34 9.2 Typical Application ................................................. 34 10 Power Supply Recommendations ..................... 38 11 Layout................................................................... 38 11.1 Layout Guidelines ................................................. 38 11.2 Layout Example .................................................... 41 12 Device and Documentation Support ................. 43 12.1 12.2 12.3 12.4 12.5 Device Support .................................................... Documentation Support ........................................ Trademarks ........................................................... Electrostatic Discharge Caution ............................ Glossary ................................................................ 43 43 43 43 43 13 Mechanical, Packaging, and Orderable Information ........................................................... 43 4 Revision History NOTE: Page numbers for previous revisions may differ from page numbers in the current version. Changes from Revision K (March 2013) to Revision L • Added Device Information and ESD Ratings tables, Detailed Description, Application and Implementation, Power Supply Recommendations, Layout, Device and Documentation Support and Mechanical, Packaging, and Orderable Information sections; moved some curves to Application Curves section ............................................................................. 1 Changes from Revision J (March 2013) to Revision K • 2 Page Page Changed layout of National Data Sheet to TI format ........................................................................................................... 34 Submit Documentation Feedback Copyright © 2009–2014, Texas Instruments Incorporated Product Folder Links: LM3530 LM3530 www.ti.com SNVS606L – JUNE 2009 – REVISED DECEMBER 2014 5 I2C Device Options ORDERABLE NUMBER I2C DEVICE OPTION LM3530TME-40 0x38 LM3530TMX-40 0x38 LM3530UME-25A 0x36 LM3530UME-40 0x38 LM3530UME-40B 0x39 LM3530UMX-25A 0x36 LM3530UMX-40 0x38 LM3530UMX-40B 0x39 6 Pin Configuration and Functions DSBGA (YFZ or YFQ) Package 12 Pins Top View A1 A2 A3 B1 B2 B3 C1 C2 C3 D1 D2 D3 Pin Functions PIN TYPE DESCRIPTION NUMBER NAME A1 SDA I/O Serial data connection for I2C-compatible interface. A2 SCL I Serial data connection for I2C-compatible interface. A3 SW PWR B1 PWM I External PWM brightness control input and simple enable input. B2 INT O Logic interrupt output signaling the ALS zone has changed. B3 GND C1 ALS2 C2 C3 Inductor connection, diode anode connection, and drain connection for internal NFET. Connect the inductor and diode as close as possible to SW to reduce parasitic inductance and capacitive coupling to nearby traces. Ground I Ambient light sensor input 2 with programmable internal pull-down resistor. HWEN I Active high hardware enable (active low reset). pull this pin high to enable the LM3530. IN PWR D1 ALS1 I Ambient light sensor input 1 with programmable internal pulldown resistor. D2 OVP I Output voltage sense connection for overvoltage sensing. Connect OVP to the positive terminal of the output capacitor. D3 ILED PWR Input voltage connection. Connect a 2.7-V to 5.5-V supply to IN and bypass to GND with a 2.2µF or greater ceramic capacitor. Input terminal to internal current sink. The boost converter regulates ILED to 0.4 V. Submit Documentation Feedback Copyright © 2009–2014, Texas Instruments Incorporated Product Folder Links: LM3530 3 LM3530 SNVS606L – JUNE 2009 – REVISED DECEMBER 2014 www.ti.com 7 Specifications 7.1 Absolute Maximum Ratings over operating free-air temperature range (unless otherwise noted) (1) (2) (3) VIN to GND MIN MAX –0.3 6 VSW, VOVP, VILED to GND 45 VSCL, VSDA, VALS1, VPWM, VINT, VHWEN to GND 6 VALS2 to GND Internally limited Junction temperature (TJ-MAX) Storage temperature, Tstg (3) (4) 150 °C 150 °C See (4) Maximum lead temperature (soldering, 10s) (2) V –0.3 V to VIN + 0.3 V Continuous power dissipation (1) UNIT –65 Stresses beyond those listed under Absolute Maximum Ratings may cause permanent damage to the device. These are stress ratings only, which do not imply functional operation of the device at these or any other conditions beyond those indicated under Recommended Operating Conditions. Exposure to absolute-maximum-rated conditions for extended periods may affect device reliability. If Military/Aerospace specified devices are required, please contact the Texas Instruments Sales Office/ Distributors for availability and specifications. All voltages are with respect to the potential at the GND pin. For detailed soldering specifications and information, please refer to Application Note 1112: DSBGA Wafer Level Chip Scale Package (SNVA009). 7.2 ESD Ratings V(ESD) (1) Human-body model (HBM), per ANSI/ESDA/JEDEC JS-001 (1) Electrostatic discharge VALUE UNIT ±2000 V JEDEC document JEP155 states that 500-V HBM allows safe manufacturing with a standard ESD control process. 7.3 Recommended Operating Conditions over operating free-air temperature range (unless otherwise noted) MIN VIN to GND NOM MAX 2.7 5.5 0 40 Junction temperature (TJ) (1) –40 125 Ambient temperature (TA) (2) –40 85 VSW, VOVP, VILED, to GND (1) (2) UNIT V °C Internal thermal shutdown circuitry protects the device from permanent damage. Thermal shutdown engages at TJ= 140°C (typ.) and disengages at TJ= 125°C (typ.). 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 (RθJA), as given by the following equation: TA-MAX = TJ-MAX-OP – (RθJA × PD-MAX). 7.4 Thermal Information DSBGA THERMAL METRIC (1) YFQ YFZ UNIT 12 PINS RθJA (1) (2) 4 Junction-to-ambient thermal resistance (2) 61.7 °C/W For more information about traditional and new thermal metrics, see the IC Package Thermal Metrics application report, SPRA953. Junction-to-ambient thermal resistance (RθJA) is taken from a thermal modeling result, performed under the conditions and guidelines set forth in the JEDEC standard JESD51-7. The test board is a 4-layer FR-4 board measuring 102 mm x 76 mm x 1.6 mm with a 2 x 1 array of thermal vias. The ground plane on the board is 50 mm x 50 mm. Thickness of copper layers are 36 µm/18 µm/18 µm/3 6µm (1.5oz/1oz/1oz/1.5oz). Ambient temperature in simulation is 22°C in still air. Power dissipation is 1W. The value of RθJA of this product in the DSBGA package could fall in a range as wide as 60ºC/W to 110ºC/W (if not wider), depending on PCB material, layout, and environmental conditions. In applications where high maximum power dissipation exists special care must be paid to thermal dissipation issues. Submit Documentation Feedback Copyright © 2009–2014, Texas Instruments Incorporated Product Folder Links: LM3530 LM3530 www.ti.com SNVS606L – JUNE 2009 – REVISED DECEMBER 2014 7.5 Electrical Characteristics Typical (TYP) limits are for TA = 25°C; minimum (MIN) and maximum (MAX) apply over the full operating ambient temperature range (−40°C ≤ TA ≤ 85°C); VIN = 3.6 V, unless otherwise specified. (1) (2) PARAMETER TEST CONDITIONS 2.7 V ≥ VIN ≥ 5.5 V, Full-scale current = 19 mA, BRT Code = 0x7F, ALS Select Bit = 0, I2C Enable = 1 ILED Output current regulation VREG_CS Regulated current sink headroom voltage VHR Current sink minimum headroom voltage ILED = 95% of nominal RDSON NMOS switch on resistance ISW = 100 mA ICL NMOS switch current limit 2.7 V ≤ VIN ≤ 5.5 V MIN TYP MAX UNIT 17.11 18.6 20.08 mA 400 mV 200 mV 839 936 ON Threshold, 2.7 V ≤ VIN ≤ 5.5 40-V V version 40 41 42 25-V version 23.6 24 24.6 450 500 VOVP Output overvoltage protection fSW Switching frequency DMAX Maximum duty cycle DMIN Minimum duty cycle IQ Quiescent current, device not switching VHWEN = VIN 490 IQ_SW Switching supply current ILED = 19 mA, VOUT = 36 V 1.35 ISHDN Shutdown current VHWEN = GND, 2.7 V ≥ VIN ≥ 5.5 V ILED_MIN Minimum LED current Full-scale current = 19 mA setting BRT = 0x01 VALS Ambient light sensor reference voltage 2.7 V ≥ VIN ≥ 5.5 V Hysteresis VHWEN TSD (3) V 550 kHz 600 µA 94% 10% 1 mA 2 9.5 µA µA (3) Logic thresholds - logic low Logic thresholds - logic high 0.97 1 1.03 0 0.4 1.2 VIN 140 Hysteresis (1) (2) mA 1 2.7 V ≤ VIN ≤ 5.5 V Thermal shutdown RALS1, RALS2 Ω 0.25 739 V °C 15 ALS input internal pull-down 2.7 V ≥ VIN ≥ 5.5 V resistors V 12.77 13.531 14.29 8.504 9.011 9.518 5.107 5.411 5.715 2.143 2.271 2.399 1.836 1.946 2.055 1.713 1.815 1.917 1.510 1.6 1.69 1.074 1.138 1.202 0.991 1.050 1.109 0.954 1.011 1.068 0.888 0.941 0.994 0.717 0.759 0.802 0.679 0.719 0.760 0.661 0.700 0.740 0.629 0.666 0.704 kΩ All voltages are with respect to the potential at the GND pin. Min and Max limits are verified by design, test, or statistical analysis. Typical (typ.) numbers are not verified, but represent the most likely norm. The ALS voltage specification is the maximum trip threshold for the ALS zone boundary (Code 0xFF). Due to random offsets and the mechanism for which the hysteresis voltage varies, it is recommended that only Codes 0x04 and above be used for Zone Boundary Thresholds. See Zone Boundary Trip Points and Hysteresis and Minimum Zone Boundary Settings sections. Submit Documentation Feedback Copyright © 2009–2014, Texas Instruments Incorporated Product Folder Links: LM3530 5 LM3530 SNVS606L – JUNE 2009 – REVISED DECEMBER 2014 www.ti.com Electrical Characteristics (continued) Typical (TYP) limits are for TA = 25°C; minimum (MIN) and maximum (MAX) apply over the full operating ambient temperature range (−40°C ≤ TA ≤ 85°C); VIN = 3.6 V, unless otherwise specified.(1)(2) PARAMETER TEST CONDITIONS MIN TYP MAX UNIT V LOGIC VOLTAGE SPECIFICATIONS (SCL, SDA, PWM, INT) VIL Input logic low 2.7 V ≤ VIN ≤ 5.5 V 0 0.54 VIH Input logic high 2.7 V ≤ VIN ≤ 5.5 V 1.26 VIN V VOL Output logic low (SDA, INT) ILOAD = 3 mA 400 mV 7.6 I2C-Compatible Timing Requirements (SCL, SDA) (1) MIN NOM MAX UNIT t1 SCL (Clock Period) 2.5 µs t2 Data in setup time to SCL high 100 ns t3 Data out stable after SCL low 0 ns t4 SDA low setup time to SCL low (start) 100 ns t5 SDA high hold time after SCL High (stop) 100 ns (1) SCL and SDA must be glitch-free in order for proper brightness control to be realized. 7.7 Simple Interface Timing MIN NOM MAX tPWM_HIGH Enable time, PWM pin must be held high 1.5 2 2.6 tPWM_LOW Disable time, PWM pin must be held low 1.48 2 2.69 UNIT ms t1 SCL t5 t4 SDIO Data In t2 SDIO Data Out t3 2 Figure 1. I C-Compatible Timing t > tPWM_HIGH(MAX) t < tPWM_HIGH(MIN) t > tPWM_LOW(MAX) t < tPWM_LOW(MIN) Figure 2. Simple Enable/Disable Timing 6 Submit Documentation Feedback Copyright © 2009–2014, Texas Instruments Incorporated Product Folder Links: LM3530 LM3530 www.ti.com SNVS606L – JUNE 2009 – REVISED DECEMBER 2014 7.8 Typical Characteristics VIN = 3.6 V, LEDs are OVSRWAC1R6 from OPTEK Technology, COUT = 1 µF, CIN = 1 µF, L = TDK VLF5012ST-100M1R0, (RL = 0.24 Ω), ILED = 19 mA, TA = 25°C, unless otherwise specified. IFULL_SCALE = 19 mA Figure 3. LED Current vs VIN Figure 4. Shutdown Current vs VIN ALS Resistor Select Register = 0x44 TA = 85°C Figure 5. Internal ALS Resistor vs VIN TA = −40°C ALS Resistor Select Register = 0x44 ALS Resistor Select Register = 0x44 Figure 6. Internal ALS Resistor vs VIN VOUT Rising Figure 7. Internal ALS Resistor vs VIN Figure 8. Overvoltage Protection vs VIN Submit Documentation Feedback Copyright © 2009–2014, Texas Instruments Incorporated Product Folder Links: LM3530 7 LM3530 SNVS606L – JUNE 2009 – REVISED DECEMBER 2014 www.ti.com Typical Characteristics (continued) VIN = 3.6 V, LEDs are OVSRWAC1R6 from OPTEK Technology, COUT = 1 µF, CIN = 1 µF, L = TDK VLF5012ST-100M1R0, (RL = 0.24 Ω), ILED = 19 mA, TA = 25°C, unless otherwise specified. Figure 9. Max Duty Cycle vs VIN Figure 10. NFET Switch On-Resistance vs VIN Figure 11. Switching Frequency vs VIN Figure 12. Simple Enable Time vs VIN ILED Full Scale = 19 mA Figure 13. Simple Disable Time vs VIN 8 Submit Documentation Feedback 50% Duty Cycle Figure 14. ILED vs FPWM Copyright © 2009–2014, Texas Instruments Incorporated Product Folder Links: LM3530 LM3530 www.ti.com SNVS606L – JUNE 2009 – REVISED DECEMBER 2014 Typical Characteristics (continued) VIN = 3.6 V, LEDs are OVSRWAC1R6 from OPTEK Technology, COUT = 1 µF, CIN = 1 µF, L = TDK VLF5012ST-100M1R0, (RL = 0.24 Ω), ILED = 19 mA, TA = 25°C, unless otherwise specified. Channel 2: SDA (5V/div) Channel 3: ILED (10mA/div) 1.024ms/Step Up And Down Time Base (40ms/div) Channel 2: SDA (5V/div) Channel 3: ILED (10mA/div) 2.048ms/Step Up And Down Figure 15. Ramp Rate (Exponential) Channel 2: SDA (5V/div) Channel 3: ILED (10mA/div) 4.096ms/Step Up And Down Time Base (200ms/div) Figure 16. Ramp Rate (Exponential) Channel 2: SDA (5V/div) Channel 3: ILED (10mA/div) 8.192ms/Step Up And Down Time Base (1s/div) Time Base (400ms/div) Figure 18. Ramp Rate (Exponential) Figure 17. Ramp Rate (Exponential) Channel 2: SDA (5V/div) Channel 3: ILED (10mA/div) 16.384ms/Step Up And Down Time Base (100ms/div) Channel 2: SDA (5V/div) Channel 3: ILED (10mA/div) 32.768ms/Step Up And Down Figure 19. Ramp Rate (Exponential) Time Base (2s/div) Figure 20. Ramp Rate (Exponential) Submit Documentation Feedback Copyright © 2009–2014, Texas Instruments Incorporated Product Folder Links: LM3530 9 LM3530 SNVS606L – JUNE 2009 – REVISED DECEMBER 2014 www.ti.com Typical Characteristics (continued) VIN = 3.6 V, LEDs are OVSRWAC1R6 from OPTEK Technology, COUT = 1 µF, CIN = 1 µF, L = TDK VLF5012ST-100M1R0, (RL = 0.24 Ω), ILED = 19 mA, TA = 25°C, unless otherwise specified. Channel 2: SDA (5V/div) Channel 3: ILED (10mA/div) 65.538ms/Step Up And Down Time Base (4s/div) Channel 1: IIN (200mA/div) Channel 3: VOUT (20V/div) Channel 4 (10mA/div) L = 22 µH VIN = 3.6V Figure 21. Ramp Rate (Exponential) Channel 1: VIN (500mV/div) Channel 2: VOUT (500mV/div) Channel 3: ILED (500µA/div) VIN From 3.6 V To 3.2 V Figure 22. Start-up Plot Time Base (400µs/div) L = 22 µH ILED = 19 mA Figure 23. Line Step Response Time Base (2ms/div) Ramp Rate = 8µs/Step ILED = 19mA Channel 2: PWM (5V/div) Channel 4: ILED (5mA/div) DPWM From 30% To 70% Time Base (2ms/div) ILED Full Scale = 19 mA FPWM = 5 kHz Figure 24. ILED Response To Step Change In PWM Duty Cycle Closed Loop L = 22 µH The value for current limit given in the Electrical Characteristics is measured in an open loop test by forcing current into SW until the current limit comparator threshold is reached. The typical curve for current limit is measured in closed loop using the typical application circuit by increasing IOUT until the peak inductor current stops increasing. Closed loop data appears higher due to the delay between the comparator trip point and the NFET turning off. This delay allows the closed loop inductor current to ramp higher after the trip point by approximately 100 ns × VIN/L. Figure 25. Current Limit vs VIN 10 Submit Documentation Feedback Copyright © 2009–2014, Texas Instruments Incorporated Product Folder Links: LM3530 LM3530 www.ti.com SNVS606L – JUNE 2009 – REVISED DECEMBER 2014 8 Detailed Description 8.1 Overview The LM3530 utilizes an asynchronous step-up, current mode, PWM controller and regulated current sink to provide an efficient and accurate LED current for white LED bias. The device powers a single series string of LEDs with output voltages of up to 40 V and a peak inductor current of typically 839 mA. The input active voltage range is from 2.7 V to 5.5 V. 8.2 Functional Block Diagram IN OVP Boost Control 40V Thermal shutdown 400mV SOFT START SW Light Load OVP 140C ERROR AMP + - R RZ R R R 250m: S HWEN R Driver CC Osc/ Ramp SCL Over Current Protection I2C/CONTROL SDA ¦ GND gm INT Zone Change Flag Current Control Mapping Mode Select Bit (0 = Exponental, 1 = Linear) 1bit Dig Code Active Zone Target Register 7 bits 1 Zone Targets X 5 BRT Register Note 1 7 bits A 3 bits ALS Input Select DAC 7 bits 0 7 bits 7 bits LED Ramp Rate Control Averager/ Discriminator ALS Select Ramp Rate Increasing 3 bits Ramp Rate Decreasing Zone Change Flag Full Scale Current Select Bits ALS2 8 bits ALS1 Resistor Select (4 Bits) Zone Boundaries X4 ALS2 Resistor Select (4 Bits) PWM Polarity Bit (0 = active high, 1 = active low) I FS ILED ( 5 mA - 30 mA ) ALS1 ADC CODE Full Scale Current Note 3 EN_PWM bit LPF Note 2 D PWM PWM Note 1: ACODE Is a Scaler between 0 and 1 based on the Brightness Data or Zone Target Data Depending on the ALS Select Bit Note 2: DPWM Is a Scaler between 0 and 1 and corresponds to the duty cycle of the PWM input signal Note 3: For EN_PWM bit = 1 ILED = IFS x ACODE x DPWM For EN_PWM bit = 0 ILED = IFS x ACODE Submit Documentation Feedback Copyright © 2009–2014, Texas Instruments Incorporated Product Folder Links: LM3530 11 LM3530 SNVS606L – JUNE 2009 – REVISED DECEMBER 2014 www.ti.com 8.3 Feature Description 8.3.1 Start-Up An internal soft-start prevents large inrush currents during start-up that can cause excessive current spikes at the input. For the typical application circuit (using a 10-µH inductor, a 2.2-µF input capacitor, and a 1-µF output capacitor) the average input current during start-up ramps from 0 to 300 mA in 3 ms. See Figure 22 in the Typical Characteristics. 8.3.2 Light Load Operation The LM3530 boost converter operates in three modes: continuous conduction, discontinuous conduction, and skip mode. Under heavy loads when the inductor current does not reach zero before the end of the switching period, the device switches at a constant frequency (500 kHz typical). As the output current decreases and the inductor current reaches zero before the end of the switching period, the device operates in discontinuous conduction. At very light loads the LM3530 will enter skip mode operation causing the switching period to lengthen and the device to only switch as required to maintain regulation at the output. Light load operation provides for improved efficiency at lighter LED currents compared to continuous and discontinuous conduction. This is due to the pulsed frequency operation resulting in decreased switching losses in the boost converter. 8.3.3 Ambient Light Sensor The LM3530 incorporates a dual input Ambient Light Sensing interface (ALS1 and ALS2) which translates an analog output ambient light sensor to a user-specified brightness level. The ambient light sensing circuit has 4 programmable boundaries (ZB0 – ZB3) which define 5 ambient brightness zones. Each ambient brightness zone corresponds to a programmable brightness threshold (Z0T – Z4T). The ALS interface is programmable to accept the ambient light information from either the highest voltage of ALS1 or ALS2, the average voltage of ALS1 or ALS2, or selectable from either ALS1 or ALS2. Furthermore, each ambient light sensing input (ALS1 or ALS2) features 15 internal software selectable voltage setting resistors. This allows the LM3530 the capability of interfacing with a wide selection of ambient light sensors. Additionally, the ALS inputs can be configured as high impedance, thus providing for a true shutdown during low power modes. The ALS resistors are selectable through the ALS Resistor Select Register (see Table 9). Figure 26 shows a functional block diagram of the ambient light sensor input. VSNS represents the active input as described in Table 6 bits [6:5]. Vdd ALS Path Functional Diagram Vsns VOUT Zone Averager (LPF) 0 Zline 1 Zline 2 Zline 3 Zline Input Light Zone Definiton Registers A/D Discriminator 7 bits ALS Resistor Select Register 8 bits ALSRS User Selectable w/ Typical Defaults Light output Targets for Each of 5 Ambient Light zones Z0 target light 7 bits Z1 target light Z 2 target light Z 3 target light Z 4 target light 0 1 2 3 4 7 bits Brightness User Selectable w/ Typical Defaults 1 0 7 bits Ramp control 7 bits LED Driver 3 bits ALS Select Ramp Rate Selection Figure 26. Ambient Light Sensor Functional Block Diagram 12 Submit Documentation Feedback Copyright © 2009–2014, Texas Instruments Incorporated Product Folder Links: LM3530 LM3530 www.ti.com SNVS606L – JUNE 2009 – REVISED DECEMBER 2014 Feature Description (continued) 8.3.4 ALS Operation The ambient light sensor input has a 0-V to 1-V operational input voltage range. LM3530 Typical Application shows the LM3530 with dual ambient light sensors (AVAGO, APDS-9005) and the internal ALS Resistor Select Register set to 0x44 (2.27 kΩ). This circuit converts 0 to 1000 LUX light into approximately a 0-mV to 850-mV linear output voltage. The voltage at the active ambient light sensor input (ALS1 or ALS2) is compared against the 8 bit values programmed into the Zone Boundary Registers (ZB0-ZB3). When the ambient light sensor output crosses one of the ZB0 – ZB3 programmed thresholds the internal ALS circuitry will smoothly transition the LED current to the new 7 bit brightness level as programmed into the appropriate Zone Target Register (Z0T – Z4T) (see Figure 27). The ALS Configuration Register bits [6:5] programs which input is the active input, bits [4:3] control the on/off state of the ALS circuitry, and bits [2:0] control the ALS input averaging time. Additionally, the ALS Information Register is a read-only register which contains a flag (bit 3) which is set each time the active ALS input changes to a new zone. This flag is reset when the register is read back. Bits [2:0] of this register contain the current active zone information. Vals_ref = 1V Full Scale Zone 4 ZB3 ZB1 Zone 2 LED Current Vsense Zone 3 ZB2 Zone 1 ZB0 Zone 0 Z0T Ambient Light (lux) Z1T Z2T Z3T Z4T LED Driver Input Code (0-127) Figure 27. Ambient Light Input To Backlight Mapping 8.3.5 ALS Averaging Time The ALS Averaging Time is the time over which the Averager block collects samples from the A/D converter and then averages them to pass to the discriminator block (see Figure 26). Ambient light sensor samples are averaged and then further processed by the discriminator block to provide rejection of noise and transient signals. The averager is configurable with 8 different averaging times to provide varying amounts of noise and transient rejection (see Table 5). The discriminator block algorithm has a maximum latency of two averaging cycles; therefore, the averaging time selection determines the amount of delay that will exist between a steadystate change in the ambient light conditions and the associated change of the backlight illumination. For example, the A/D converter samples the ALS inputs at 16 kHz. If the averaging time is set to 1024 ms then the Averager will send the updated zone information to the discriminator every 1024 ms. This zone information contains the average of 16384 samples (1024 ms × 16 kHz). Due to the latency of 2 averaging cycles, the LED current will not change until there has been a steady-state change in the ambient light for at least 2 averaging periods. 8.3.5.1 Averager Operation The magnitude and direction (either increasing or decreasing) of the Averager output is used to determine whether the LM3530 should change brightness zones. The Averager block functions as follows: 1. First, the Averager always begins with a Zone 0 reading stored at start-up. If the main display LEDs are active before the ALS block is enabled, it is recommended that the ALS Enable 1 bit is set to '1' at least 3 averaging periods before the ALS Enable 2 bit is set. Submit Documentation Feedback Copyright © 2009–2014, Texas Instruments Incorporated Product Folder Links: LM3530 13 LM3530 SNVS606L – JUNE 2009 – REVISED DECEMBER 2014 www.ti.com Feature Description (continued) 2. The Averager will always round down to the lower zone in the event of a non-integer zone average. For example, if during an averaging period the ALS input transitions between zones 1 and 2 resulting in an averager output of 1.75, then the averager output will round down to 1 (see Figure 28). 3. The two most current averaging samples are used to make zone change decisions. 4. To make a zone change, data from three averaging cycles are needed. (Starting Value, First Transition, Second Transition or Rest). 5. To Increase the brightness zone, the Averager output must have increased for at least 2 averaging periods or increased and remained at the new level for at least two averaging periods ('+' to '+' or '+' to 'Rest' in Figure 29). 6. To decrease the brightness zone, the Averager output must have decreased for at least 2 averaging periods or decreased and remained at the new level for at least two averaging periods ('-' to '-' or '-' to 'Rest' in Figure 29). In the case of two consecutive increases or decreases in the Averager output, the LM3530 will transition to zone equal to the last averager output (Figure 29). Using the diagram for the ALS block (Figure 26), the flow of information is shown in (Figure 30). This starts with the ALS input into the A/D, into the Averager, and then into the Discriminator. Each state filters the previous output to help prevent unwanted zone to zone transitions. When using the ALS averaging function, it is important to remember that the averaging cycle is free running and is not synchronized with changing ambient lighting conditions. Due to the nature of the averager round down, an increase in brightness can take between 2 and 3 averaging cycles to change zones, while a decrease in brightness can take between 1 and 2 averaging cycles. See Table 6 for a list of possible Averager periods. Figure 31 shows an example of how the perceived brightness change time can vary. Zone 4 Zone 3 Averager Output Zone 2 µ5¶= Rest, µ+¶= Increase, µ-µ= Decrease Zone 1 Zone 4 Zone 0 Zone Average Averager Output Zone 3 1.0 1.75 3.5 4.0 2.25 2.25 1.5 1 1 3 4 2 2 1 Zone 2 Zone 1 Zone 0 R Figure 28. Averager Calculation Brightness Zone + 0 R 0 + 1 + 1 + 3 R 4 R 4 4 Zone 4 Zone 3 Zone 2 Zone 1 Zone 0 R Brightness Zone 4 R 4 3 3 1 R 0 R 0 0 Zone 4 Zone 3 Zone 2 Zone 1 Zone 0 R Brightness Zone + 0 + 0 4 + 4 4 4 R 1 1 Figure 29. Brightness Zone Change Examples 14 Submit Documentation Feedback Copyright © 2009–2014, Texas Instruments Incorporated Product Folder Links: LM3530 LM3530 www.ti.com SNVS606L – JUNE 2009 – REVISED DECEMBER 2014 1 Ave Period 1 Ave Period Zone4 Zone3 ALS Input Zone2 Zone4 Zone1 Zone3 Zone0 Averager Output Zone2 1 1 3 4 2 2 Zone1 1 Zone0 tBRGT-CHANGE = 2.75 Average Time Averager Output Zone4 tBRGT-CHANGE = 1.75 Average Time Zone3 Zone2 Figure 30. Ambient Light Input To Backlight Transition Zone1 Zone0 LED Brightness Zone Zone4 Zone3 Zone2 Zone1 Zone0 Figure 31. Perceived Brightness Change Time 8.3.6 Zone Boundary Settings Registers 0x60, 0x61, 0x62, and 0x63 set the 4 zone boundaries (thresholds) for the ALS inputs. These 4 zone boundaries create 5 brightness zones which map over to 5 separate brightness zone targets (see Figure 27). Each 8-bit zone boundary register can set a threshold from typically 0 to 1 V with linear step sizes of approximately 1/255 = 3.92 mV. Additionally, each zone boundary has built in hysteresis which can be either lower or higher then the programmed Zone Boundary depending on the last direction (either up or down) of the ALS input voltage. 8.3.7 Zone Boundary Trip Points and Hysteresis For each zone boundary setting, the trip point will vary above or below the nominal set point depending on the direction (either up or down) of the ALS input voltage. This is designed to keep the ALS input from oscillating back and forth between zones in the event that the ALS voltage is residing near to the programmed zone boundary threshold. The Zone Boundary Hysteresis will follow these 2 rules: 1. If the last zone transition was from low to high, then the trip point (VTRIP) will be VZONE_BOUNDARY - VHYST/2, where VZONE_BOUNDARY is the zone boundary set point as programmed into the Zone Boundary registers, and VHYST is typically 7 mV. 2. If the last zone transition was from high to low then the trip point (VTRIP) will be VZONE_BOUNDARY + VHYST/2. Figure 32 details how the LM3530 ALS Input Zone Boundary Thresholds vary depending on the direction of the ALS input voltage. Referring to Figure 32, each numbered trip point shown is determined from the direction of the previous ALS zone transition. Submit Documentation Feedback Copyright © 2009–2014, Texas Instruments Incorporated Product Folder Links: LM3530 15 LM3530 SNVS606L – JUNE 2009 – REVISED DECEMBER 2014 www.ti.com 1V Zone 4 VHYST 2 VZB3 + Zone Boundary 3 VZB3 - VHYST 2 Zone 3 ALS Input Voltage #1 VHYST VZB2 + 2 Zone Boundary 2 VZB2 - VHYST 2 #8 #3 Zone 2 #2 VHYST VZB1 + 2 Zone Boundary 1 VZB1 - VHYST 2 #4 #7 Zone 1 #5 #6 VHYST VZB0 + 2 Zone Boundary 0 VZB0 - VHYST 2 Zone 0 Figure 32. Zone Boundaries With Hysteresis 8.3.8 Minimum Zone Boundary Settings The actual minimum zone boundary setting is code 0x03. Codes of 0x00, 0x01, and 0x02 are all mapped to code 0x03. Table 1 shows the Zone Boundary codes 0x00 through 0x04, the typical thresholds, and the high and low hysteresis values. The remapping of codes 0x00 - 0x02 plus the additional 4mV of offset voltage is necessary to prevent random offsets and noise on the ALS inputs from creating threshold levels that are below GND. This essentially guarantees that any Zone Boundary threshold selected is achievable with positive ALS voltages. Table 1. Ideal Zone Boundary Settings with Hysteresis (Lower 5 Codes) 16 ZONE BOUNDARY CODE TYPICAL ZONE BOUNDARY THRESHOLD (mV) TYPICAL THRESHOLD + HYSTERESIS (mV) TYPICAL THRESHOLD HYSTERESIS (mV) 0x00 15.8 19.3 12.3 0x01 15.8 19.3 12.3 0x02 15.8 19.3 12.3 0x03 15.8 19.3 12.3 0x04 19.7 23.2 16.2 Submit Documentation Feedback Copyright © 2009–2014, Texas Instruments Incorporated Product Folder Links: LM3530 LM3530 www.ti.com SNVS606L – JUNE 2009 – REVISED DECEMBER 2014 8.3.9 LED Current Control The LED current is is a function of the Full Scale Current, the Brightness Code, and the PWM input duty cycle. The Brightness Code can either come from the BRT Register (0xA0) in I2C-Compatible Current Control, or from the ALS Zone Target Registers (Address 0x70-0x74) in Ambient Light Current Control. Figure 33 shows the current control block diagram. VOUT Mapping Mode Select Bit (0 = Exponental, 1 = Linear) Active Zone Target Register BRT Register Dig Code 7 bits 1 1bit 7 bits LED Ramp Rate Control DAC 7 bits 0 7 bits Note 1 3 bits ALS Select Ramp Rate Increasing Full Scale Current Select Bits 3 bits A CODE 3 bits Ramp Rate Decreasing IFS ( 5 mA - 30 mA) Full Scale Current LED Driver I LED PWM Polarity Bit (0 = active high, 1 = active low) EN_PWM bit Note 3 LPF PWM Note 2 DPWM Note 1: ACODE Is a Scaler between 0 and 1 based on the Brightness Data or Zone Target Data Depending on the ALS Select Bit Note 2: DPWM Is a Scaler between 0 and 1 and corresponds to the duty cycle of the PWM input signal Note 3: For EN_PWM bit = 1 ILED = IFS x ACODE x DPWM For EN_PWM bit = 0 ILED = IFS x ACODE Figure 33. Current Control Block Diagram 8.3.10 Exponential or Linear Brightness Mapping Modes With bit [1] of the General Configuration Register set to 0 (default) exponential mapping is selected and the code in the Brightness Control Register corresponds to the Full-Scale LED current percentages in Table 2 and Figure 34. With bit [1] set to 1 linear mapping is selected and the code in the Brightness Control Register corresponds to the Full-Scale LED current percentages in Table 3 and Figure 35. 8.3.11 PWM Input Polarity Bit [6] of the General Configuration Register controls the PWM input polarity. Setting this bit to 0 (default) selects positive polarity and makes the LED current (with PWM mode enabled) a function of the positive duty cycle at PWM. With this bit set to ‘0’ the LED current (with PWM mode enabled) becomes a function of the negative duty cycle at PWM. The PWM input is a logic level input with a frequency range of 400 Hz to 50 kHz. Internal filtering of the PWM input signal converts the duty cycle information to an average (analog) control signal which directly controls the LED current. Submit Documentation Feedback Copyright © 2009–2014, Texas Instruments Incorporated Product Folder Links: LM3530 17 LM3530 SNVS606L – JUNE 2009 – REVISED DECEMBER 2014 www.ti.com Example: PWM + I2C-Compatible Current Control: As an example, assume the the General Configuration Register is loaded with (0x2D). From Table 5, this sets up the LM3530 with: Simple Enable OFF (bit 7 = 0) Positive PWM Polarity (bit 6 = 0) PWM Enabled (bit 5 = 1) Full-Scale Current set at 15.5 mA (bits [4:2] = 100) Brightness Mapping set for Exponential (bit 1 = 0) Device Enabled via I2C (bit 0 = 1) Next, the Brightness Control Register is loaded with 0x73. This sets the LED current to 51.406% of full scale (see Equation 1). Finally, the PWM input is driven with a 0-V to 2-V pulse waveform at 70% duty cycle. The LED current under these conditions will be: ILED = ILED _ FS x BRT x D = 15. 5 mA x 51. 4% x 70% | 5. 58 mA. where • BRT is the percentage of ILED_FS as set in the Brightness Control Register (1) 8.3.12 I2C-Compatible Current Control Only I2C-Compatible Control is enabled by writing a '1' to the I2C Device Enable bit (bit [0] of the General Configuration Register), a '0' to the Simple Enable bit (bit 7), and a '0' to the PWM Enable bit (bit 5). With bit 5 = 0, the duty cycle information at the PWM input is not used in setting the LED current. In this mode the LED current is a function of the Full-Scale LED current bits (bits [4:2] of the General Configuration Register) and the code in the Brightness Control Register. The LED current mapping for the Brightness Control Register can be linear or exponential depending on bit [1] in the General Configuration Register (see Exponential or Linear Brightness Mapping Modes section). Using I2C-Compatible Control Only, the Full-Scale LED Current bits and the Brightness Control Register code provides nearly 1016 possible current levels selectable over the I2C-compatible interface. Example: I2C-Compatible Current Control Only: As an example, assume the General Configuration Register is loaded with 0x15. From Table 5 this sets up the LM3530 with: Simple Enable OFF (bit 7 = 0) Positive PWM Polarity (bit 6 = 0) PWM Disabled (bit 5 = 0) Full-Scale Current set at 22.5mA (bits [4:2] = 101) Brightness Mapping set for Exponential (bit 1 = 0) Device Enabled via I2C (bit 0 = 1) The Brightness Control Register is then loaded with 0x72 (48.438% of full-scale current from Equation 2). The LED current with this configuration becomes: ILED = ILED _ FS x BRT = 22 . 5 mA x 0.48438 | 10.9 mA. where • BRT is the % of ILED_FS as set in the Brightness Control Register. (2) Next, the brightness mapping is set to linear mapping mode (bit [1] in General Configuration Register set to 1). Using the same Full-Scale current settings and Brightness Control Register settings as before, the LED current becomes: ILED = ILED _ FS x BRT = 22 . 5 mA x 0.8976 | 20.2 mA. (3) Which is higher now since the code in the Brightness Control Register (0x72) corresponds to 89.76% of FullScale LED Current due to the different mapping mode given in Figure 34. 18 Submit Documentation Feedback Copyright © 2009–2014, Texas Instruments Incorporated Product Folder Links: LM3530 LM3530 SNVS606L – JUNE 2009 – REVISED DECEMBER 2014 LED CURRENT (% of ILED_MAX SETTING) www.ti.com 100 10 1 0.1 0.01 1 8 15 22 29 36 43 50 57 64 71 78 85 92 99 106 113 120 127 CODE (DECMIL) Figure 34. Exponential Brightness Mapping Table 2. ILED vs. Brightness Register Data (Exponential Mapping) BRT DATA (HEX) % FULL-SCALE CURRENT BRT DATA (HEX) % OF FULLSCALE CURRENT BRT DATA (HEX) % OF FULLSCALE CURRENT BRT DATA (HEX) % OF FULLSCALE CURRENT 0x00 0.00% 0x20 0.500% 0x40 2.953% 0x60 17.813% 0x01 0.080% 0x21 0.523% 0x41 3.125% 0x61 18.750% 0x02 0.086% 0x22 0.555% 0x42 3.336% 0x62 19.922% 0x03 0.094% 0x23 0.586% 0x43 3.500% 0x63 20.859% 0x04 0.102% 0x24 0.617% 0x44 3.719% 0x64 22.266% 0x05 0.109% 0x25 0.656% 0x45 3.906% 0x65 23.438% 0x06 0.117% 0x26 0.695% 0x46 4.141% 0x66 24.844% 0x07 0.125% 0x27 0.734% 0x47 4.375% 0x67 26.250% 0x08 0.133% 0x28 0.773% 0x48 4.648% 0x68 27.656% 0x09 0.141% 0x29 0.820% 0x49 4.922% 0x69 29.297% 0x0A 0.148% 0x2A 0.867% 0x4A 5.195% 0x6A 31.172% 0x0B 0.156% 0x2B 0.914% 0x4B 5.469% 0x6B 32.813% 0x0C 0.164% 0x2C 0.969% 0x4C 5.781% 0x6C 34.453% 0x0D 0.172% 0x2D 1.031% 0x4D 6.125% 0x6D 35.547% 0x0E 0.180% 0x2E 1.078% 0x4E 6.484% 0x6E 38.828% 0x0F 0.188% 0x2F 1.148% 0x4F 6.875% 0x6F 41.016% 0x10 0.203% 0x30 1.219% 0x50 7.266% 0x70 43.203% 0x11 0.211% 0x31 1.281% 0x51 7.656% 0x71 45.938% 0x12 0.227% 0x32 1.359% 0x52 8.047% 0x72 48.438% 0x13 0.242% 0x33 1.430% 0x53 8.594% 0x73 51.406% 0x14 0.250% 0x34 1.523% 0x54 9.063% 0x74 54.141% 0x15 0.266% 0x35 1.594% 0x55 9.609% 0x75 57.031% 0x16 0.281% 0x36 1.688% 0x56 10.078% 0x76 60.703% 0x17 0.297% 0x37 1.781% 0x57 10.781% 0x77 63.984% 0x18 0.320% 0x38 1.898% 0x58 11.250% 0x78 67.813% 0x19 0.336% 0x39 2.016% 0x59 11.953% 0x79 71.875% 0x1A 0.352% 0x3A 2.109% 0x5A 12.656% 0x7A 75.781% 0x1B 0.375% 0x3B 2.250% 0x5B 13.359% 0x7B 79.688% 0x1C 0.398% 0x3C 2.367% 0x5C 14.219% 0x7C 84.375% Submit Documentation Feedback Copyright © 2009–2014, Texas Instruments Incorporated Product Folder Links: LM3530 19 LM3530 SNVS606L – JUNE 2009 – REVISED DECEMBER 2014 www.ti.com Table 2. ILED vs. Brightness Register Data (Exponential Mapping) (continued) % FULL-SCALE CURRENT BRT DATA (HEX) % OF FULLSCALE CURRENT BRT DATA (HEX) % OF FULLSCALE CURRENT BRT DATA (HEX) % OF FULLSCALE CURRENT 0x1D 0.422% 0x3D 2.508% 0x5D 15.000% 0x7D 89.844% 0x1E 0.445% 0x3E 2.648% 0x5E 15.859% 0x7E 94.531% 0x1F 0.469% 0x3F 2.789% 0x5F 16.875% 0x7F 100.00% LED CURRENT (% of ILED_MAX SETTING) BRT DATA (HEX) 100 90 80 70 60 50 40 30 20 10 0 1 8 15 22 29 36 43 50 57 64 71 78 85 92 99 106 113 120 127 CODE (DECMIL) Figure 35. Linear Brightness Mapping Table 3. ILED vs. Brightness Register Data (Linear Mapping) 20 BRT DATA (HEX) % FULLSCALE CURREN T (LINEAR) BRT DATA (HEX) % OF FULLSCALE CURRENT (LINEAR) BRT DATA (HEX) % OF FULLSCALE CURRE NT (LINEA R) BRT DATA (HEX) % OF FULL-SCALE CURRENT (LINEAR) 0x00 0.00% 0x20 25.79% 0x40 50.78% 0x60 75.78% 0x01 1.57% 0x21 26.57% 0x41 51.57% 0x61 76.56% 0x02 2.35% 0x22 27.35% 0x42 52.35% 0x62 77.35% 0x03 3.13% 0x23 28.13% 0x43 53.13% 0x63 78.13% 0x04 3.91% 0x24 28.91% 0x44 53.91% 0x64 78.91% 0x05 4.69% 0x25 29.69% 0x45 54.69% 0x65 79.69% 0x06 5.48% 0x26 30.47% 0x46 55.47% 0x66 80.47% 0x07 6.26% 0x27 31.25% 0x47 56.25% 0x67 81.25% 0x08 7.04% 0x28 32.04% 0x48 57.03% 0x68 82.03% 0x09 7.82% 0x29 32.82% 0x49 57.82% 0x69 82.81% 0x0A 8.60% 0x2A 33.60% 0x4A 58.60% 0x6A 83.59% 0x0B 9.38% 0x2B 34.38% 0x4B 59.38% 0x6B 84.38% 0x0C 10.16% 0x2C 35.16% 0x4C 60.16% 0x6C 85.16% 0x0D 10.94% 0x2D 35.94% 0x4D 60.94% 0x6D 85.94% 0x0E 11.72% 0x2E 36.72% 0x4E 61.72% 0x6E 86.72% 0x0F 12.51% 0x2F 37.50% 0x4F 62.50% 0x6F 87.50% 0x10 13.29% 0x30 38.29% 0x50 63.28% 0x70 88.28% 0x11 14.07% 0x31 39.07% 0x51 64.06% 0x71 89.06% 0x12 14.85% 0x32 39.85% 0x52 64.85% 0x72 89.84% Submit Documentation Feedback Copyright © 2009–2014, Texas Instruments Incorporated Product Folder Links: LM3530 LM3530 www.ti.com SNVS606L – JUNE 2009 – REVISED DECEMBER 2014 Table 3. ILED vs. Brightness Register Data (Linear Mapping) (continued) BRT DATA (HEX) % FULLSCALE CURREN T (LINEAR) BRT DATA (HEX) % OF FULLSCALE CURRENT (LINEAR) BRT DATA (HEX) % OF FULLSCALE CURRE NT (LINEA R) BRT DATA (HEX) % OF FULL-SCALE CURRENT (LINEAR) 0x13 15.63% 0x33 40.63% 0x53 65.63% 0x73 90.63% 0x14 16.41% 0x34 41.41% 0x54 66.41% 0x74 91.41% 0x15 17.19% 0x35 42.19% 0x55 67.19% 0x75 92.19% 0x16 17.97% 0x36 42.97% 0x56 67.97% 0x76 92.97% 0x17 18.76% 0x37 43.75% 0x57 68.75% 0x77 93.75% 0x18 19.54% 0x38 44.53% 0x58 69.53% 0x78 94.53% 0x19 20.32% 0x39 45.32% 0x59 70.39% 0x79 95.31% 0x1A 21.10% 0x3A 46.10% 0x5A 71.10% 0x7A 96.09% 0x1B 21.88% 0x3B 46.88% 0x5B 71.88% 0x7B 96.88% 0x1C 22.66% 0x3C 47.66% 0x5C 72.66% 0x7C 97.66% 0x1D 23.44% 0x3D 48.44% 0x5D 73.44% 0x7D 98.44% 0x1E 24.22% 0x3E 49.22% 0x5E 74.22% 0x7E 99.22% 0x1F 25.00% 0x3F 50.00% 0x5F 75.00% 0x7F 100.00% NOTE When determining the LED current from (Table 2 and Table 3 ) there is a typical offset of 113 µA with a ±300-µA variation that must be added to the calculated value for codes 0x0A and below. For example, in linear mode with IFULL_SCALE = 19 mA and brightness code 0x09 chosen, the nominal current setting is 0.0782 × 19 mA = 1.4858 mA. Adding in the 113-µA typical offset gives 1.4858 mA + 0.113 mA = 1.5988 mA. With the typical ±300-µA range, the high and low currents can be ILOW = 1.2988 mA, IHIGH = 1.8988 mA. For exponential mode with codes 0x0A and below, this offset and variation error gets divided down by 10 (11.3 µA offset with ±30-µA typical range). 8.3.13 Simple Enable Disable With PWM Current Control With bits [7 and 5] of the General Configuration Register set to ‘1’ the PWM input is enabled as a simple enable/disable. The simple enable/disable feature operates as described in Figure 36. In this mode, when the PWM input is held high (PWM Polarity bit = 0) for > 2 ms the LM3530 will turn on the LED current at the programmed Full-Scale Current × % of Full-Scale Current as set by the code in the Brightness Control Register. When the PWM input is held low for > 2 ms the device will shut down. With the PWM Polarity bit = 1 the PWM input is configured for active low operation. In this configuration holding PWM low for > 2 ms will turn on the device at the programmed Full-Scale Current × % of Full-Scale Current as set by the code in the Brightness Control Register. Likewise, holding PWM high for > 2 ms will put the device in shutdown. Driving the PWM input with a pulsed waveform at a variable duty cycle is also possible in simple enable/Disable mode, so long as the low pulse width is < 2 ms. When a PWM signal is used in this mode the input duty cycle information is internally filtered, and an analog voltage is used to control the LED current. This type of PWM control (PWM to Analog current control) prevents large voltage excursions across the output capacitor that can result in audible noise. Simple Enable/Disable mode can be useful since the default bit setting for the General Configuration Register is 0xCC (Simple Enable bit = 1, PWM Enable = 1, and Full-Scale Current = 19mA). Additionally, the default Brightness Register setting is 0x7F (100% of Full-Scale current). This gives the LM3530 the ability to turn on after power up (or after reset) without having to do any writes to the I2C-compatible bus. Submit Documentation Feedback Copyright © 2009–2014, Texas Instruments Incorporated Product Folder Links: LM3530 21 LM3530 SNVS606L – JUNE 2009 – REVISED DECEMBER 2014 www.ti.com t > tPWM_HIGH(MAX) t < tPWM_HIGH(MIN) t > tPWM_LOW(MAX) t < tPWM_LOW(MIN) Figure 36. Simple Enable/Disable Timing Example: Simple Enable Disable with PWM Current Control): As an example, assume that the HWEN input is toggled low then high. This resets the LM3530 and sets all the registers to their default value. When the PWM input is then pulled high for > 2 ms the LED current becomes: ILED = ILED _ FS x BRT x D = 19 mA x 1.00 x 100 % | 19 mA. where • BRT is the % of ILED_FS as set in the Brightness Control Register. (4) If then the PWM input is fed with a 5-kHz pulsed waveform at 40% duty cycle the LED current becomes: ILED = ILED _ FS x BRT x D = 19 mA x 1.00 x 0.4 | 7.6 mA. (5) Then, if the Brightness Control Register is loaded with 0x55 (9.6% of Full-Scale Current) the LED current becomes: ILED = ILED _ FS x BRT x D = 19 mA x 9.65 x 0.4 | 0.73 mA. (6) 8.3.14 Ambient Light Current Control With bits [4:3] of the ALS Configuration Register both set to 1, the LM3530 is configured for Ambient Light Current Control. In this mode the ambient light sensing inputs (ALS1, and/or ALS2) monitor the outputs of analog output ambient light sensing photo diodes and adjust the LED current depending on the ambient light. The ambient light sensing circuit has 4 configurable Ambient Light Boundaries (ZB0 – ZB3) programmed through the four (8-bit) Zone Boundary Registers. These zone boundaries define 5 ambient brightness zones (Figure 27). Each zone corresponds to a programmable brightness setting which is programmable through the 5 Zone Target Registers (Z0T – Z4T). When the ALS1, and/or ALS2 input (depending on the bit settings of the ALS Input Select bits) detects that the ambient light has crossed to a new zone (as defined by one of the Zone Boundary Registers) the LED current becomes a function of the Brightness Code loaded in the Zone Target Register which corresponds to the new ambient light brightness zone. On start-up the 4 Zone Boundary Registers are pre-loaded with 0x33 (51d), 0x66 (102d), 0x99 (153d), and 0xCC (204d). Each ALS input has a 1-V active input voltage range with a 4mV offset voltage which makes the default Zone Boundaries set at: Zone Boundary 0 = 1V × 51/255 + 4 mV = 204 mV Zone Boundary 1 = 1V × 102/255 + 4 mV = 404 mV Zone Boundary 2 = 1V × 153/255 + 4 mV = 604 mV Zone Boundary 3 = 1V × 204/255 + 4 mV = 804 mV These Zone Boundary Registers are all 8-bit (readable and writable) registers. The first zone (Z0) is defined between 0 and 204 mV, the Z1 default is defined between 204 mV and 404 mV, the Z2 default is defined between 404 mV and 604 mV, the Z3 default is defined between 604 mV and 804 mV, and the Z4 default is defined between 804 mV and 1.004 V. The default settings for the 5 Zone Target Registers are 0x19, 0x33, 0x4C, 0x66, and 0x7F. This corresponds to LED brightness settings of 0.336%, 1.43%, 5.781%, 24.844%, and 100% of full-scale current respectively (assuming exponential backlight mapping). Example: Ambient Light Control Current: 22 Submit Documentation Feedback Copyright © 2009–2014, Texas Instruments Incorporated Product Folder Links: LM3530 LM3530 www.ti.com SNVS606L – JUNE 2009 – REVISED DECEMBER 2014 As an example, assume that the APDS-9005 is used as the ambient light sensing photo diode with its output connected to the ALS1 input. The ALS Resistor Select Register is loaded with 0x04 which configures the ALS1 input for a 2.27-kΩ internal pull-down resistor (see Table 9). The APDS-9005 has a typical 400nA/LUX response. With a 2.27-kΩ resistor the sensor output would see a 0-mV to 908-mV swing with a 0 to 1000 LUX change in ambient light. Next, the ALS Configuration Register is programmed with 0x3C. From Table 6, this configures the LM3530’s ambient light sensing interface for: ALS1 as the active ALS input (bits [6:5] = 01) Ambient Light Current Control Enabled (bit 4 = 1) ALS circuitry Enabled (bit 3 = 1) Sets the ALS Averaging Time to 512 ms (bits [2:0] = 100) Next, the General Configuration Register is programmed with 0x19 which sets the Full-Scale Current to 26 mA, selects Exponential Brightness Mapping, and enables the device via the I2C-compatible interface. Now assume that the APDS-9005 ambient light sensor detects a 100 LUX ambient light at its input. This forces the ambient light sensors output (and the ALS1 input) to 87.5mV corresponding to Zone 0. Since Zone 0 points to the brightness code programmed in Zone Target Register 0 (loaded with code 0x19), the LED current becomes: ILED = ILED_FS u ZoneTarget0 = 26 mA u 0.336% | 87 PA. (7) Where the code in Zone Target Register 0 points to the % of ILED_FS as given by Table 2 or Table 3, depending on whether Exponential or Linear Mapping are selected. Next, assume that the ambient light changes to 500 LUX (corresponding to an ALS1 voltage of 454 mV). This moves the ambient light into Zone 2 which corresponds to Zone Target Register 2 (loaded with code 0x4C) the LED current then becomes: ILED = ILED _ FS x ZoneTarget2 = 26 mA x 5.781% | 1.5 mA. (8) 8.3.15 Ambient Light Current Control + PWM The Ambient Light Current Control can also be a function of the PWM input duty cycle. Assume the LM3530 is configured as described in the above Ambient Light Current Control example, but this time the Enable PWM bit set to ‘1’ (General Configuration Register bit [5]). Example: Ambient Light Current Control + PWM In this example, the APDS-9005 detects that the ambient light has changed to 1 kLUX. The voltage at ALS1 is now around 908 mV, and the ambient light falls within Zone 5. This causes the LED brightness to be a function of Zone Target Register 5 (loaded with 0x7F). Now assume the PWM input is also driven with a 50% duty cycle pulsed waveform. The LED current now becomes: ILED = ILED _ FS x ZoneTarget5 x D = 26 mA x 100% x 50% | 13 mA. (9) Submit Documentation Feedback Copyright © 2009–2014, Texas Instruments Incorporated Product Folder Links: LM3530 23 LM3530 SNVS606L – JUNE 2009 – REVISED DECEMBER 2014 www.ti.com Example: ALS Averaging: As an example, suppose the LM3530 ALS Configuration Register is loaded with 0x3B. This configures the device for: ALS1 as the active ALS input (bits [6:5] = 01) Enables Ambient Light Current Control (bit 4 = 1) Enables the ALS circuitry (bit 3 = 1) Sets the ALS Averaging Time to 256 ms (bits [2:0] = 011) Next, the ALS Resistor Select Register is loaded with 0x04. This configures the ALS2 input as high impedance and configures the ALS1 input with a 2.27-kΩ internal pull-down resistor. The Zone Boundary Registers and Zone Target Registers are left with their default values. The Brightness Ramp Rate Register is loaded with 0x2D. This sets up the LED current ramp rate at 16.384 ms/step. Finally, the General Configuration Register is loaded with 0x15. This sets up the device with: Simple Enable OFF (bit 7 = 0) PWM Polarity High (bit 6 = 0) PWM Input Disabled (bit 5 = 0) Full-Scale Current = 22.5mA (bits [4:2] = 101) Brightness Mapping Mode as Exponential (bit 1 = 0) Device Enabled via I2C (bit 0 = 1) As the device starts up the APDS-9005 ambient light sensor (connected to the ALS1 input) detects 500 LUX. This puts approximately 437.5 mV at ALS1 (see Figure 37). This places the measured ambient light between Zone Boundary Registers 1 and 2, thus corresponding to Zone Target Register 2. The default value for this register is 0x4C. The LED current is programmed to: ILED = ILED _ FS x ZoneTarget2 = 22.5 mA x 5.781% | 1.3 mA . (10) Referring to Figure 37, initially the Averager is loaded with Zone 0 so it takes 2 averaging periods for the LM3530 to change to the new zone. After the ALS1 voltage remains at 437.5 mV for two averaging periods (end of period 2) the LM3530 repeats Zone 2 and signals the LED current to begin ramping to the Zone 2 target beginning at average period 3. Since the ramp rate is set at 16.384 ms/step the LED current goes from 0 to 1.3 mA in 76 × 16.384 ms = 1.245s (approximately 5 average periods). After the LED current has been at its steady state of 1.3 mA for a while, the ambient light suddenly steps to 900 LUX for 500 ms and then steps back to 500 LUX. In this case the 900 LUX will place the ALS1 voltage at approximately 979 mV corresponding to Zone 4 somewhere during average period 10 and fall back to 437.5 mV somewhere during average period 12. The averager output during period #10 goes to 3, and then during period 11, goes to 4. Since there have been 2 increases in the average during period 10 and period 11, the beginning of average period #12 shows a change in the brightness zone to Zone 4. This results in the LED current ramping to the new value of 22.5 mA (the Zone 4 target). During period #12 the ambient light steps back to 500 LUX and forces ALS1 to 437.5 mV (corresponding to Zone 2). After average period 12 and period 13 have shown that the averager transitioned lower two times, the brightness zone changes to the new target at the beginning of period 14. This signals the LED current to ramp down to the zone 2 target of 1.3 mA. Looking back at average period 12 and period 13, the LED current was only able to ramp up to 7.38 mA due to the ramp rate of 16.384 ms/step (2 average periods of 256 ms each) before it was instructed to ramp back to the Zone 2 target at the start of period 14. This example demonstrates not only the averaging feature, but how additional filtering of transient events on the ALS inputs can be accomplished by using the LED current ramp rates. 24 Submit Documentation Feedback Copyright © 2009–2014, Texas Instruments Incorporated Product Folder Links: LM3530 LM3530 www.ti.com SNVS606L – JUNE 2009 – REVISED DECEMBER 2014 LM3530 turns on and averaging begins 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 979 mV (900 LUX) VALS1 437.5 mV (500 LUX) 0 mV 4 3 3 2 2 ALS Average Zone 4 Zone 2 Zone 2 Brightness Zone Zone 0 7.38 mA LED Current 1.3 mA 0 Figure 37. ALS Averaging Example 8.3.16 Interrupt Output INT is an open-drain output which pulls low when the Ambient Light Sensing circuit has transitioned to a new ambient brightness zone. When a read-back of the ALS Information Register is done INT is reset to the open drain state. 8.3.17 Overvoltage Protection Overvoltage protection is set at 40 V (minimum) for the LM3530-40 and 23.6 V minimum for the LM3530-25. The 40-V version allows typically up to 11 series white LEDs (assuming 3.5 V per LED + 400 mV headroom voltage for the current sink = 38.9 V). When the OVP threshold is reached the LM3530 switching converter stops switching, allowing the output voltage to discharge. Switching will resume when the output voltage falls to typically 1 V below the OVP threshold. In the event of an LED open circuit the output will be limited to around 40 V with a small amount of voltage ripple. The 25-V version allows up to 6 series white LEDs (assuming 3.5-V per LED + 400 mV headroom voltage for the current sink = 21.4 V). The 25-V OVP option allows for the use of lower voltage and smaller sized (25 V) output capacitors. The 40-V device would typically require a 50-V output capacitor. 8.3.18 Hardware Enable The HWEN input is an active high hardware enable which must be pulled high to enable the device. Pulling this pin low disables the I2C-compatible interface, the simple enable/disable input, the PWM input, and resets all registers to their default state (see Table 4). Submit Documentation Feedback Copyright © 2009–2014, Texas Instruments Incorporated Product Folder Links: LM3530 25 LM3530 SNVS606L – JUNE 2009 – REVISED DECEMBER 2014 www.ti.com 8.3.19 Thermal Shutdown In the event the die temperature reaches 140°C, the LM3530 will stop switching until the die temperature cools by 15°C. In a thermal shutdown event the device is not placed in reset; therefore, the contents of the registers are left in their current state. 8.4 Device Functional Modes 8.4.1 Shutdown With HWEN Low, or bit 0 in register 0x10 set to 0, the device is in shutdown. In this mode the boost converter and the current sink are both off and the supply current into IN is reduced to typically 1 µA. 8.4.2 I2C Mode I2C-Compatible Control Mode is enabled by writing a '1' to the I2C Device Enable bit (bit [0] of the General Configuration Register), a '0' to the Simple Enable bit (bit 7), and a '0' to the PWM Enable bit (bit 5). With bit 5 = 0, the duty cycle information at the PWM input is not used in setting the LED current. In this mode the LED current is a function of the Full-Scale LED current bits (bits [4:2] of the General Configuration Register) and the code in the Brightness Control Register. The LED current mapping for the Brightness Control Register can be linear or exponential depending on bit [1] in the General Configuration Register (see Exponential or Linear Brightness Mapping Modes section). Using I2C-Compatible Control Only, the Full-Scale LED Current bits and the Brightness Control Register code provides nearly 1016 possible current levels selectable over the I2C-compatible interface. 8.4.3 PWM + I2C Mode PWM + I2C-compatible current control mode is enabled by writing a ‘1’ to the Enable PWM bit (General Configuration Register bit [5]) and writing a ‘1’ to the I2C Device Enable bit (General Configuration Register bit 0). This makes the LED current a function of the PWM input duty cycle (D), the Full-Scale LED current (ILED_FS), and the % of full-scale LED current . The % of Full-Scale LED current is set by the code in the Brightness Control Register. The LED current using PWM + I2C-Compatible Control is given by Equation 11: ILED = I LED_ FS x BRT x D (11) BRT is the percentage of Full Scale Current as set in the Brightness Control Register. The Brightness Control Register can have either exponential or linear brightness mapping depending on the setting of the BMM bit (bit [1] in General Configuration Register). 8.4.4 ALS Mode With bits [4:3] of the ALS Configuration Register both set to 1, the LM3530 is configured for Ambient Light Current Control. In this mode the ambient light sensing inputs (ALS1, and/or ALS2) monitor the outputs of analog output ambient light sensing photo diodes and adjust the LED current depending on the ambient light. 8.4.5 Simple Enable Mode Simple Enable Mode With bits [7 and 5] of the General Configuration Register set to ‘1’ the PWM input is enabled as a simple enable/disable. The simple enable/disable feature operates as described in Figure 36. In this mode, when the PWM input is held high (PWM Polarity bit = 0) for > 2 ms the LM3530 will turn on the LED current at the programmed Full-Scale Current × % of Full-Scale Current as set by the code in the Brightness Control Register. When the PWM input is held low for > 2 ms the device will shut down. 26 Submit Documentation Feedback Copyright © 2009–2014, Texas Instruments Incorporated Product Folder Links: LM3530 LM3530 www.ti.com SNVS606L – JUNE 2009 – REVISED DECEMBER 2014 8.5 Programming 8.5.1 I2C-Compatible Interface 8.5.1.1 Start and Stop Condition The LM3530 is controlled via an I2C-compatible interface. START and STOP conditions classify the beginning and the end of the I2C session. A START condition is defined as SDA transitioning from HIGH to LOW while SCL is HIGH. A STOP condition is defined as SDA transitioning from LOW to HIGH while SCL is HIGH. The I2C master always generates the START and STOP conditions. The I2C bus is considered busy after a START condition and free after a STOP condition. During data transmission, the I2C master can generate repeated START conditions. A START and a repeated START conditions are equivalent function-wise. The data on SDA must be stable during the HIGH period of the clock signal (SCL). In other words, the state of SDA can only be changed when SCL is LOW. SDA SCL S P Start Condition Stop Condition Figure 38. Start and Stop Sequences 8.5.1.2 I2C-Compatible Address The 7bit chip address for the LM3530 is (0x38, or 0x39) for the 40-V version and (0x36) for the 25-V version. After the START condition, the IC master sends the 7-bit chip address followed by an eighth bit (LSB) read or write (R/W). R/W= 0 indicates a WRITE and R/W = 1 indicates a READ2. The second byte following the chip address selects the register address to which the data will be written. The third byte contains the data for the selected register. I2C Compatible Address MSB 0 Bit 7 1 Bit 6 1 Bit 5 1 Bit 4 0 Bit 3 LSB 0 Bit 2 0 Bit 1 R/W Bit 0 Figure 39. I2C-Compatible Chip Address (0x38) I2C Compatible Address MSB 0 Bit 7 LSB 1 Bit 6 1 Bit 5 0 Bit 4 1 Bit 3 1 Bit 2 0 Bit 1 R/W Bit 0 Figure 40. I2C-Compatible Chip Address (0x36) 8.5.1.3 Transferring Data Every byte on the SDA line must be eight bits long, with the most significant bit (MSB) transferred first. Each byte of data must be followed by an acknowledge bit (ACK). The acknowledge related clock pulse (9th clock pulse) is generated by the master. The master then releases SDA (HIGH) during the 9th clock pulse. The LM3530 pulls down SDA during the 9th clock pulse, signifying an acknowledge. An acknowledge is generated after each byte has been received. There are fourteen 8-bit registers within the LM3530 as detailed in Table 4. Submit Documentation Feedback Copyright © 2009–2014, Texas Instruments Incorporated Product Folder Links: LM3530 27 LM3530 SNVS606L – JUNE 2009 – REVISED DECEMBER 2014 www.ti.com 8.6 Register Maps 8.6.1 Register Descriptions Table 4. LM3530 Register Definition REGISTER NAME ADDRESS POR VALUE General Configuration 1. Simple Interface Enable 2. PWM Polarity 3. PWM enable 4. Full-Scale Current Selection 5. Brightness Mapping Mode Select 6. I2C Device Enable FUNCTION 0x10 0xB0 ALS Configuration 1. ALS Current Control Enable 2. ALS Input Enable 3. ALS Input Select 4. ALS Averaging Times 0x20 0x2C Brightness Ramp Rate Programs the rate of rise and fall of the LED current 0x30 0x00 ALS Zone Information 1. Zone Boundary Change Flag 2. Zone Brightness Information 0x40 0x00 ALS Resistor Select Internal ALS1 and ALS2 Resistances 0x41 0x00 Brightness Control (BRT) Holds the 7 bit Brightness Data 0xA0 0x7F Zone Boundary 0 (ZB0) ALS Zone Boundary #0 0x60 0x33 Zone Boundary 1 (ZB1) ALS Zone Boundary #1 0x61 0x66 Zone Boundary 2 (ZB2) ALS Zone Boundary #2 0x62 0x99 Zone Boundary 3 (ZB3) ALS Zone Boundary #3 0x63 0xCC Zone Target 0 (Z0T) Zone 0 LED Current Data. The LED Current Source transitions to the brightness code in Z0T when the ALS_ input is less than the zone boundary programmed in ZB0. 0x70 0x19 Zone Target 1 (Z1T) Zone 1 LED Current Data. The LED Current Source transitions to the brightness code in Z1T when the ALS_ input is between the zone boundaries programmed in ZB1 and ZB0. 0x71 0x33 Zone Target 2 (Z2T) Zone 2 LED Current Data. The LED Current Source transitions to the brightness code in Z2T when the ALS_ input is between the zone boundaries programmed in ZB2 and ZB1. 0x72 0x4C Zone Target 3 (Z3T) Zone 3 LED Current Data. The LED Current Source transitions to the brightness code in Z3T when the ALS_ input is between the zone boundaries programmed in ZB3 and ZB2. 0x73 0x66 Zone Target 4 (Z4T) Zone 4 LED Current Data. The LED Current Source transitions to the brightness code in Z4T when the ALS_ input is between the zone boundaries programmed in ZB4 and ZB3. 0x74 0x7F 28 Submit Documentation Feedback Copyright © 2009–2014, Texas Instruments Incorporated Product Folder Links: LM3530 LM3530 www.ti.com SNVS606L – JUNE 2009 – REVISED DECEMBER 2014 *Note: Unused bits in the LM3530 Registers default to a logic '1'. 8.6.1.1 General Configuration Register (GP) The General Configuration Register (address 0x10) is described in Figure 41 and Table 5. General Configuration Register Address 0x10, Default Value 0xB0 MSB Bit 7 Simple Interface Enable Bit 6 PWM Polarity Bit 5 PWM Enable Bit 4 Full Scale Current Select Bit 3 Full Scale Current Select LSB Bit 2 Full Scale Current Select Bit 1 Brightness Mapping Mode Select Bit 0 I2C Interface Enable Figure 41. General Configuration Register Table 5. General Configuration Register Description (0x10) Bit 7 (PWM Simple Enable 0 = Simple Interface at PWM Input is Disabled 1 = Simple Interface at PWM Input is Enabled Bit 6 (PWM Polarity) Bit 5 (EN_PWM) see Figure 31 0 = PWM active high 1 = PWM active low 0 = LED current is not a function of PWM duty cycle 1 = LED current is a function of duty cycle Bit 4 (Full-Scale Current Select) Bit 3 (Full-Scale Current Select) Bit 2 (Full-Scale Current Select) Bit 1 (Mapping Mode Select) 000 = 5 mA full-scale current 001 = 8.5 mA full-scale current 010 = 12 mA full-scale current 011 = 15.5 mA full-scale current 100 = 19 mA full-scale current 101 = 22.5 mA full-scale current 110 = 26 mA full-scale current 111 = 29.5 mA full-scale current 0 = exponential mapping 1 = linear mapping Bit 0 (I2C Device Enable) 0 = Device Disabled 1 = Device Enabled 8.6.1.2 ALS Configuration Register The ALS Configuration Register controls the Ambient Light Sensing input functions and is described in Figure 42 and Table 6. ALS Configuration Register Address 0x20, Default Value 0x2C MSB Bit 7 (Not Used) Bit 6 ALS Input Select 2 Bit 5 ALS Input Select 1 Bit 4 ALS Mode Bit 3 ALS Enable LSB Bit 2 ALS Averaging Time Bit 1 ALS Averaging Time Bit 0 ALS Averaging Time Figure 42. ALS Configuration Register Table 6. ALS Configuration Register Description (0x20) Bit 7 N/A Bit 6 ALS Input Select Bit 5 ALS Input Select 00 = The Average of ALS1 and ALS2 is used to control the LED brightness 01 = ALS1 is used to control the LED brightness 10 = ALS2 is used to control the LED brightness 11 = The ALS input with the highest voltage is used to control the LED brightness Bit 4 ALS Enable Bit 3 ALS Enable 00 or 10 = ALS is disabled. The Brightness Register is used to determine the LED current. 01 = ALS is enabled. The Brightness Register is used to determine the LED Current. 11 = ALS inputs are enabled. Ambient light determines the LED current. Bit 2 ALS Averaging Time Bit 1 ALS Averaging Time Bit 0 ALS Averaging Time 000 = 32 ms 001 = 64 ms 010 = 128 ms 011 = 256 ms 100 = 512 ms 101 = 1024 ms 110 = 2048 ms 111 = 4096 ms Submit Documentation Feedback Copyright © 2009–2014, Texas Instruments Incorporated Product Folder Links: LM3530 29 LM3530 SNVS606L – JUNE 2009 – REVISED DECEMBER 2014 www.ti.com 8.6.1.3 Brightness Ramp Rate Register The Brightness Ramp Rate Register controls the rate of rise or fall of the LED current. Both the rising rate and falling rate are independently adjustable Figure 43 and Table 7 describe the bit settings. Brightness Ramp Rate Register Address 0x30, Default Value 0x00 MSB Bit 7 Not Used Bit 6 Not Used Bit 5 BRRI2 Bit 4 BRRI1 LSB Bit 2 BRRD2 Bit 3 BRRI0 Bit 1 BRRD1 Bit 0 BRRD0 Figure 43. Brightness Ramp Rate Register Table 7. Brightness Ramp Rate Register Description (0x30) Bit 7 Bit 6 N/A N/A Bit 5 (BRRI2) Bit 4 (BRRI1) Bit 3 (BRRI0) 000 = 8 µs/step (1.106 ms from 0 to Full Scale) 001 = 1.024 ms/step (130 ms from 0 to Full Scale) 010 = 2.048 ms/step (260 ms from 0 to Full Scale) 011 = 4.096 ms/step (520 ms from 0 to Full Scale) 100 = 8.192 ms/step (1.04 s from 0 to Full Scale) 101 = 16.384 ms/step (2.08 s from 0 to Full Scale) 110 = 32.768 ms/step (4.16 s from 0 to Full Scale) 111 = 65.538 ms/step (8.32 s from 0 to Full Scale) Bit 2 (BRRD2) Bit 1 (BRRD1) Bit 0 (BRRD0) 000 = 8 µs/step (1.106 ms from Full Scale to 0) 001 = 1.024 ms/step (130 ms from Full Scale to 0) 010 = 2.048 ms/step (260 ms from Full Scale to 0) 011 = 4.096 ms/step (520 ms from Full Scale to 0) 100 = 8.192 ms/step (1.04 s from Full Scale to 0) 101 = 16.384 ms/step (2.08 s from Full Scale to 0) 110 = 32.768 ms/step (4.16 s from Full Scale to 0) 111 = 65.538 ms/step (8.32 s from Full Scale to 0) 8.6.1.4 ALS Zone Information Register The ALS Zone Information Register is a read-only register that is updated every time the active ALS input(s) detect that the ambient light has changed to a new zone as programmed in the Zone Boundary Registers. See Zone Boundary Register description. A new update to the ALS Zone Information Register is signaled by the INT output going from high to low. A read-back of the ALS Zone Information Register will cause the INT output to go open-drain again. The Zone Change Flag (bit 3) is also updated on a Zone change and cleared on a read back of the ALS Zone Information Register. Figure 44 and Table 8 detail the ALS Zone Information Register. ALS Zone Information Register Address 0x40, Default Value 0x00 MSB Bit 7 (Not Used) Bit 6 Bit 5 (Not Used) (Not Used) Bit 4 (Not Used) Bit 3 Zone Boundry Change Flag LSB Bit 2 Z2 Zone Data Bit 1 Z1 Zone Data Bit 0 Z0 Zone Data Figure 44. ALS Zone Information Register Table 8. ALS Zone Information Register Description (0x40) Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 (Zone Boundary Change Flag) N/A N/A N/A N/A 1 = the active ALS input has changed to a new ambient light zone as programmed in the Zone Boundary Registers (ZB0 -ZB3) 0 = no zone change Bit 2 (Z2) Bit 1 (Z1) Bit 0 (Z0) 000 = Zone 0 001 = Zone 1 010 = Zone 2 011 = Zone 3 100 = Zone 4 8.6.1.5 ALS Resistor Select Register The ALS Resistor Select Register configures the internal resistance from either the ALS1 or ALS2 input to GND. Bits [3:0] program the input resistance at the ALS1 input and bits [7:4] program the input resistance at the ALS2 input. With bits [3:0] set to all zeroes the ALS1 input is high impedance. With bits [7:4] set to all zeroes the ALS2 input is high impedance. 30 Submit Documentation Feedback Copyright © 2009–2014, Texas Instruments Incorporated Product Folder Links: LM3530 LM3530 www.ti.com SNVS606L – JUNE 2009 – REVISED DECEMBER 2014 ALS Resistor Select Register Address 0x41, Default Value 0x00 MSB Bit 7 ALSR2A Bit 6 ALSR2B Bit 5 ALSR2C Bit 4 ALSR2D Bit 3 ALSR1A LSB Bit 2 ALSR1B Bit 1 ALSR1C Bit 0 ALSR1D Figure 45. ALS Resistor Select Register Table 9. ALS Resistor Select Register Description (0x41) Bit 7 (ALSR2A) Bit 6 (ALSR2B) Bit 5 (ALSR2C) Bit 4 (ALSR2D) Bit 3 (ALSR1A) 0000 = ALS2 is high impedance 0001 = 13.531 kΩ (73.9 µA at 1 V) 0010 = 9.011 kΩ (111 µA at 1 V) 0011 = 5.4116 kΩ (185 µA at 1 V) 0100 = 2.271 kΩ (440 µA at 1 V) 0101 = 1.946 kΩ (514 µA at 1 V) 0110 = 1.815 kΩ (551 µA at 1 V) 0111 = 1.6 kΩ (625 µA at 1 V) 1000 = 1.138 kΩ (879 µA at 1 V) 1001 = 1.05 kΩ (952 µA at 1 V) 1010 = 1.011 kΩ (989 µA at 1 V) 1011 = 941 Ω (1.063 mA at 1 V) 1100 = 759 Ω (1.318 mA at 1 V) 1101 = 719 Ω (1.391 mA at 1 V) 1110 = 700 Ω (1.429 mA at 1 V) 1111 = 667 Ω (1.499 mA at 1 V) Bit 2 (ALSR1B) Bit 1 (ALSR1C) Bit 0 (ALSR1D) 0000 = ALS2 is high impedance 0001 = 13.531 kΩ (73.9 µA at 1 V) 0010 =9.011 kΩ (111 µA at 1 V) 0011 = 5.4116 kΩ (185 µA at 1 V) 0100 = 2.271 kΩ (440 µA at 1 V) 0101 = 1.946 kΩ (514 µA at 1 V) 0110 = 1.815 kΩ (551 µA at 1 V) 0111 = 1.6 kΩ (625 µA at 1 V) 1000 = 1.138 kΩ (879µA at 1 V) 1001 = 1.05 kΩ (952 µA at 1 V) 1010 = 1.011 kΩ (989 µA at 1 V) 1011 = 941 Ω (1.063 mA at 1 V) 1100 = 759 Ω (1.318 mA at 1 V) 1101 = 719 Ω (1.391 mA at 1 V) 1110 = 700 Ω (1.429 mA at 1 V) 1111 = 667 Ω (1.499 mA at 1 V) 8.6.1.6 Brightness Control Register The Brightness Register (BRT) is an 8-bit register that programs the 127 different LED current levels (Bits [6:0]). The code written to BRT is translated into an LED current as a percentage of ILED_FULLSCALE as set via the FullScale Current Select bits (General Configuration Register bits [4:2]). The LED current response has a typical 1000:1 dimming ratio at the maximum full-scale current (General Configuration Register bits [4:2] = (111) and using the exponential weighted dimming curve. There are two selectable LED current profiles. Setting the General Configuration Register bit 1 to 0 selects the exponentially weighted LED current response (see Figure 34). Setting this bit to '1' selects the linear weighted curve (see Figure 35). Table 2 and Table 3 show the percentage Full-Scale LED Current at a given Brightness Register Code for both the Exponential and Linear current response. Brightness Control Register Address 0xA0, Default Value 0x7F MSB Bit 7 (Not Used) Bit 6 Data Bit 5 Data Bit 4 Data Bit 3 Data LSB Bit 2 Data Bit 1 Data Bit 0 Data Figure 46. Brightness Control Register Table 10. Brightness Control Register Description (0xA0) Bit 7 N/A Bit 6 Data (MSB) Bit 5 Data Bit 4 Data Bit 3 Data Bit 2 Data Bit 1 Data Bit 0 Data LED Brightness Data (Bits [6:0] Exponential Mapping (see Table 2) 0000000 = LEDs Off 0000001 = 0.08% of Full Scale : : : 1111111 = 100% of Full Scale Linear Mapping (see Table 3) 0000000 = LEDs Off 0000001 = 0.79% of Full Scale : : : 1111111 = 100% of Full Scale Submit Documentation Feedback Copyright © 2009–2014, Texas Instruments Incorporated Product Folder Links: LM3530 31 LM3530 SNVS606L – JUNE 2009 – REVISED DECEMBER 2014 www.ti.com 8.6.1.7 Zone Boundary Register The Zone Boundary Registers are programmed with the ambient light sensing zone boundaries. The default values are set at 20% (200 mV), 40% (400 mV), 60% (600 mV), and 80% (800 mV) of the full-scale ALS input voltage range (1V). The necessary conditions for proper ALS operation are that the data in ZB0 < data in ZB1 < data in ZB2 < data in ZB3. Zone Boundary Register 0 (ZB0) Address 0x60, Default Value 0x33 MSB Bit 7 Data Bit 6 Data Bit 6 Data Bit 6 Data Bit 2 Data Bit 1 Data Bit 5 Data Bit 4 Data Bit 3 Data Bit 5 Data Bit 4 Data Bit 3 Data Bit 6 Data Bit 5 Data Bit 4 Data Bit 3 Data Bit 0 Data LSB Bit 2 Data Bit 1 Data Bit 0 Data LSB Bit 2 Data Bit 1 Data Zone Boundary Register 3 (ZB3) Address 0x63, Default Value 0xCC MSB Bit 7 Data Bit 3 Data Zone Boundary Register 2 (ZB2) Address 0x62, Default Value 0x99 MSB Bit 7 Data Bit 4 Data Zone Boundary Register 1 (ZB1) Address 0x61, Default Value 0x66 MSB Bit 7 Data Bit 5 Data LSB Bit 0 Data LSB Bit 2 Data Bit 1 Data Bit 0 Data Figure 47. Zone Boundary Registers 8.6.1.8 Zone Target Registers The Zone Target Registers contain the LED brightness data that corresponds to the current active ALS zone. The default values for these registers and their corresponding percentage of full-scale current for both linear and exponential brightness is shown in Figure 48 and Table 11. 32 Submit Documentation Feedback Copyright © 2009–2014, Texas Instruments Incorporated Product Folder Links: LM3530 LM3530 www.ti.com SNVS606L – JUNE 2009 – REVISED DECEMBER 2014 Zone Target Register 0 (ZT0) Address 0x70, Default Value 0x19 MSB N/A Bit 6 Data Bit 5 Data Bit 6 Data Bit 5 Data Bit 6 Data Bit 1 Data Bit 3 Data Bit 4 Data Bit 2 Data Bit 3 Data Bit 6 Data Bit 5 Data Bit 4 Data Bit 1 Data Bit 1 Data Bit 5 Data Bit 4 Data Bit 3 Data Bit 0 Data LSB Bit 2 Data Bit 1 Data Zone Target Register 4 (ZT4) Address 0x74, Default Value 0x7F Bit 6 Data Bit 0 Data LSB Bit 2 Data Bit 3 Data Bit 0 Data LSB Zone Target Register 3 (ZT3) Address 0x73, Default Value 0x66 MSB N/A Bit 4 Data Bit 5 Data MSB N/A Bit 2 Data Zone Target Register 2 (ZT2) Address 0x72, Default Value 0x4C MSB N/A Bit 3 Data Zone Target Register 1 (ZT1) Address 0x71, Default Value 0x33 MSB N/A Bit 4 Data LSB Bit 0 Data LSB Bit 2 Data Bit 1 Data Bit 0 Data Figure 48. Zone Target Registers Table 11. Zone Boundary and Zone Target Default Mapping ZONE BOUNDARY (DEFAULT) ZONE TARGET REGISTER (DEFAULT) FULL-SCALE CURRENT (DEFAULT) LINEAR MAPPING (DEFAULT) EXPONENTIAL MAPPING (DEFAULT) Boundary 0, Active ALS input is less than 200 mV 0x19 19 mA 19.69% (3.74 µA) 0.336% (68.4 µA) Boundary 1, Active ALS input is between 200 mV and 400 mV 0x33 19 mA 40.16% (7.63 µA) 1.43% (272 µA) Boundary 2, Active ALS input is between 400 mV and 600 mV 0x4C 19 mA 59.84% (11.37 mA) 5.78% (1.098 mA) Boundary 3, Active ALS input is between 600 mV and 800 mV 0x66 19 mA 80.31% (15.26 mA) 24.84% (4.72 mA) Boundary 4, Active ALS input is greater than 800mV 0x7F 19 mA 100% (19 mA) 100% (19 mA) Submit Documentation Feedback Copyright © 2009–2014, Texas Instruments Incorporated Product Folder Links: LM3530 33 LM3530 SNVS606L – JUNE 2009 – REVISED DECEMBER 2014 www.ti.com 9 Application and Implementation NOTE Information in the following applications sections is not part of the TI component specification, and TI does not warrant its accuracy or completeness. TI’s customers are responsible for determining suitability of components for their purposes. Customers should validate and test their design implementation to confirm system functionality. 9.1 Application Information The LM3530 incorporates a 40-V (maximum output) boost, a single current sink, and a dual ambient light sensor interface. The maximum boost output voltage is 40 V (min) for the LM3530-40 version. The LM3530 boost will drive the output voltage to whatever voltage necessary to maintain 400mV at the ILED input. The 40-V max output typically allows the LM3530 to drive from 2 series up to 12 series LEDs (3.2V max voltage per LED). For applications that do not use one or both of the ALS inputs, the ALS input can be connected to GND or left floating. 9.2 Typical Application L D1 Up to 40V 2.7V to 5.5V C OUT VLOGIC SW IN 10 k: 10 k: 10 k: 10 k: C IN LM3530 SCL OVP SDA HWEN INT PWM ILED VIN Ambient Light Sensor VIN ALS1 Ambient Light Sensor ALS2 GND Figure 49. LM3530 Typical Application 9.2.1 Design Requirements Example requirements for typical voltage inverter applications: Table 12. Design Parameters DESIGN PARAMETER EXAMPLE VALUE Input voltage range 2.7 V to 5.5 V Output current 0 mA to 30 mA Boost switching frequency 500 kHz Table 13. Application Circuit Component List COMPONENT MANUFACTURER PART NUMBER VALUE SIZE CURRENT/VOLTAGE RATING L TDK VLF3014ST100MR82 10 µH 3 mm × 3 mm × 1.4 mm ISAT = 820 mA COUT Murata GRM21BR71H105KA12 1 µF 0805 50 V CIN Murata GRM188B31A225KE33 2.2 µF 0603 10 V D1 Diodes Inc. B0540WS Schottky SOD-323 40 V/500 mA ALS1 Avago APDS-9005 Ambient Light Sensor 1.6 mm x 1.5 mm × 0.6 mm 0 to 1100 Lux ALS2 Avago APDS-9005 Ambient Light Sensor 1.6 mm x 1.5 mm × 0.6 mm 0 to 1100 Lux 34 Submit Documentation Feedback Copyright © 2009–2014, Texas Instruments Incorporated Product Folder Links: LM3530 LM3530 www.ti.com SNVS606L – JUNE 2009 – REVISED DECEMBER 2014 9.2.2 Detailed Design Procedure 9.2.2.1 LED Current Setting/Maximum LED Current The maximum LED current is restricted by the following factors: the maximum duty cycle that the boost converter can achieve, the peak current limitations, and the maximum output voltage. 9.2.2.2 Maximum Duty Cycle The LM3530 can achieve up to typically 94% maximum duty cycle. Two factors can cause the duty cycle to increase: an increase in the difference between VOUT and VIN and a decrease in efficiency. This is shown by Equation 12: D=1- VIN x ä VOUT (12) For a 9-LED configuration VOUT = (3.6 V x 9LED + VHR) = 33 V operating with η = 70% from a 3-V battery, the duty cycle requirement would be around 93.6%. Lower efficiency or larger VOUT to VIN differentials can push the duty cycle requirement beyond 94%. 9.2.2.3 Peak Current Limit The LM3530 boost converter has a peak current limit for the internal power switch of 839 mA typical (739 mA minimum). When the peak switch current reaches the current limit, the duty cycle is terminated resulting in a limit on the maximum output current and thus the maximum output power the LM3530 can deliver. Calculate the maximum LED current as a function of VIN, VOUT, L, efficiency (η) and IPEAK as: IOUT_MAX = (I PEAK - 'I L ) x K x VIN VOUT 'I L = where VIN x (VOUT - VIN) 2 x fSW x L x VOUT where • • ƒSW = 500 kHz η and IPEAK can be found in the Efficiency and IPEAK curves in the Specifications and Application Curves. (13) 9.2.2.4 Output Voltage Limitations The LM3530 has a maximum output voltage of 41 V typical (40 V minimum) for the LM3530-40 version and 24 V typical (23.6 V minimum) for the LM3530-25 version. When the output voltage rises above this threshold (VOVP) the overvoltage protection feature is activated and the duty cycle is terminated. Switching will cease until VOUT drops below the hysteresis level (typically 1 V below VOVP). For larger numbers of series connected LEDs the output voltage can reach the OVP threshold at larger LED currents and colder ambient temperatures. Typically white LEDs have a –3mV/°C temperature coefficient. 9.2.2.5 Output Capacitor Selection The LM3530’s output capacitor has two functions: filtering of the boost converters switching ripple, and to ensure feedback loop stability. As a filter, the output capacitor supplies the LED current during the boost converters on time and absorbs inductor energy during the switch off time. This causes a sag in the output voltage during the on time and a rise in the output voltage during the off time. Because of this, the output capacitor must be sized large enough to filter the inductor current ripple that could cause the output voltage ripple to become excessive. As a feedback loop component, the output capacitor must be at least 1 µF and have low ESR otherwise the LM3530 boost converter can become unstable. This requires the use of ceramic output capacitors. Table 14 lists part numbers and voltage ratings for different output capacitors that can be used with the LM3530. Table 14. Recommended Input/Output Capacitors MANUFACTURER PART NUMBER VALUE (µF) SIZE RATING (V) DESCRIPTION Murata Murata GRM21BR71H105KA12 1 0805 50 COUT GRM188B31A225KE33 2.2 0805 10 TDK CIN C1608X5R0J225 2.2 0603 6.3 CIN Submit Documentation Feedback Copyright © 2009–2014, Texas Instruments Incorporated Product Folder Links: LM3530 35 LM3530 SNVS606L – JUNE 2009 – REVISED DECEMBER 2014 www.ti.com 9.2.2.6 Inductor Selection The LM3530 is designed to work with a 10-µH to 22-µH inductor. When selecting the inductor, ensure that the saturation rating for the inductor is high enough to accommodate the peak inductor current. Equation 14 and Equation 15 calculate the peak inductor current based upon LED current, VIN, VOUT, and efficiency. I PEAK = I LED VOUT + 'I L × K VIN (14) where: 'IL = VIN x (VOUT - VIN ) 2 x f SW x L x VOUT (15) When choosing L, the inductance value must also be large enough so that the peak inductor current is kept below the LM3530 switch current limit. This forces a lower limit on L given by Equation 16. VIN x (VOUT - VIN) L> § I LED _ MAX x VOUT © K x VIN 2 x f SW x VOUT x ¨ ¨I SW_MAX - · ¸¸ ¹ (16) ISW_MAX is given in , efficiency (η) is shown in the Application Curves, and ƒSW is typically 500 kHz. Table 15. Suggested Inductors MANUFACTURER PART NUMBER VALUE (µH) SIZE (mm) RATING (mA) DC RESISTANCE (Ω) TDK VLF3014ST-100MR82 10 2.8 × 3 × 1.4 820 0.25 TDK VLF3010ST-220MR34 22 2.8 × 3 × 1 340 0.81 TDK VLF3010ST-100MR53 10 2.8 × 3 × 1 530 0.41 TDK VLF4010ST-100MR80 10 2.8 × 3 × 1 800 0.25 TDK VLS252010T-100M 10 2.5 × 2 × 1 650 0.71 Coilcraft LPS3008-103ML 10 2.95 × 2.95 × 0.8 520 0.65 Coilcraft LPS3008-223ML 22 2.95 × 2.95 × 0.8 340 1.5 Coilcraft LPS3010-103ML 10 2.95 × 2.95 × 0.9 550 0.54 Coilcraft LPS3010-223ML 22 2.95 × 2.95 × 0.9 360 1.2 Coilcraft XPL2010-103ML 10 1.9 × 2 × 1 610 0.56 Coilcraft EPL2010-103ML 10 2×2×1 470 0.91 TOKO DE2810C-1117AS-100M 10 3 × 3.2 × 1 600 0.46 9.2.2.7 Diode Selection The diode connected between SW and OUT must be a Schottky diode and have a reverse breakdown voltage high enough to handle the maximum output voltage in the application. Table 16 lists various diodes that can be used with the LM3530. For 25-V OVP devices a 30-V Schottky is adequate. For 40-V OVP devices, a 40-V Schottky diode should be used. Table 16. Suggested Diodes MANUFACTURER PART NUMBER VALUE SIZE (mm) RATING Diodes Inc B0540WS Schottky SOD-323 (1.7 × 1.3) 40 V/500 mA 36 Diodes Inc SDM20U40 Schottky SOD-523 (1.2 × 0.8 × 0.6) 40 V/200 mA On Semiconductor NSR0340V2T1G Schottky SOD-523 (1.2 × 0.8 × 0.6) 40 V/250 mA On Semiconductor NSR0240V2T1G Schottky SOD-523 (1.2 × 0.8 × 0.6) 40 V/250 mA Submit Documentation Feedback Copyright © 2009–2014, Texas Instruments Incorporated Product Folder Links: LM3530 LM3530 www.ti.com SNVS606L – JUNE 2009 – REVISED DECEMBER 2014 9.2.3 Application Curves IFULL_SCALE = 19 mA IFULL_SCALE = 19 mA Figure 50. Efficiency vs VIN Figure 51. Efficiency vs VIN IFULL_SCALE = 19 mA Figure 52. Efficiency vs VIN Figure 53. Efficiency vs ILED Figure 54. Efficiency vs ILED Figure 55. Efficiency vs ILED Submit Documentation Feedback Copyright © 2009–2014, Texas Instruments Incorporated Product Folder Links: LM3530 37 LM3530 SNVS606L – JUNE 2009 – REVISED DECEMBER 2014 www.ti.com 10 Power Supply Recommendations The LM3530 operates from a 2.7-V to 5.5-V input voltage. The 500-kHz switching frequency for the boost can lead to ripple voltage on the input voltage rail. To minimize this, the input to the inductor should be well bypassed with a 1-µF (min) ceramic bypass capacitor (see Output Capacitor Selection). 11 Layout 11.1 Layout Guidelines The LM3530 contains an inductive boost converter which detects a high switched voltage (up to 40 V) at the SW pin, and a step current (up to 900 mA) through the Schottky diode and output capacitor each switching cycle. The high switching voltage can create interference into nearby nodes due to electric field coupling (I = CdV/dt). The large step current through the diode and the output capacitor can cause a large voltage spike at the SW pin and the OVP pin due to parasitic inductance in the step current conducting path (V = Ldi/dt). Board layout guidelines are geared towards minimizing this electric field coupling and conducted noise. Figure 56 highlights these two noise generating components. Voltage Spike VOUT + VF Schottky Pulsed voltage at SW Current through Schottky Diode and COUT IPEAK IAVE = IIN Paracitic Circuit Board Inductances Current through inductor Affected Node due to capacitive coupling Cp1 L Lp1 D1 Lp2 2.7V to 5.5V VLOGIC IN 10 k: Up to 40V COUT SW Lp3 10 k: SCL OVP SDA LM3530 LCD Display ILED GND Figure 56. LM3530 Boost Converter Showing Pulsed Voltage At SW (High Dv/Dt) and Current Through Schottky and COUT (High Di/Dt) 38 Submit Documentation Feedback Copyright © 2009–2014, Texas Instruments Incorporated Product Folder Links: LM3530 LM3530 www.ti.com SNVS606L – JUNE 2009 – REVISED DECEMBER 2014 Layout Guidelines (continued) The following lists the main (layout sensitive) areas of the LM3530 in order of decreasing importance: • Output Capacitor – Schottky Cathode to COUT+ – COUT– to GND • Schottky Diode – SW Pin to Schottky Anode – Schottky Cathode to COUT+ • Inductor – SW Node PCB capacitance to other traces • Input Capacitor – CIN+ to IN pin – CIN– to GND 11.1.1 Output Capacitor Placement The output capacitor is in the path of the inductor current discharge path. As a result COUT detects a high current step from 0 to IPEAK each time the switch turns off and the Schottky diode turns on. Any inductance along this series path from the cathode of the diode through COUT and back into the LM3530 GND pin will contribute to voltage spikes (VSPIKE = LP_ × dI/dt) at SW and OUT which can potentially overvoltage the SW pin, or feed through to GND. To avoid this, COUT+ must be connected as close as possible to the Cathode of the Schottky diode and COUT– must be connected as close as possible to the device GND bump. The best placement for COUT is on the same layer as the LM3530 so as to avoid any vias that can add excessive series inductance (see Figure 58, Figure 59, and Figure 60). 11.1.2 Schottky Diode Placement The Schottky diode is in the path of the inductor current discharge. As a result the Schottky diode detects a high current step from 0 to IPEAK each time the switch turns off and the diode turns on. Any inductance in series with the diode will cause a voltage spike (VSPIKE = LP_ × dI/dt) at SW and OUT which can potentially overvoltage the SW pin, or feed through to VOUT and through the output capacitor and into GND. Connecting the anode of the diode as close as possible to the SW pin and the cathode of the diode as close as possible to COUT+ will reduce the inductance (LP_) and minimize these voltage spikes (see Figure 58, Figure 59, and Figure 60 ). 11.1.3 Inductor Placement The node where the inductor connects to the LM3530 SW bump has 2 issues. First, a large switched voltage (0 to VOUT + VF_SCHOTTKY) appears on this node every switching cycle. This switched voltage can be capacitively coupled into nearby nodes. Second, there is a relatively large current (input current) on the traces connecting the input supply to the inductor and connecting the inductor to the SW bump. Any resistance in this path can cause large voltage drops that will negatively affect efficiency. To reduce the capacitively coupled signal from SW into nearby traces, the SW bump to inductor connection must be minimized in area. This limits the PCB capacitance from SW to other traces. Additionally, the other traces need to be routed away from SW and not directly beneath. This is especially true for high impedance nodes that are more susceptible to capacitive coupling such as (SCL, SDA, HWEN, PWM, and possibly ASL1 and ALS2). A GND plane placed directly below SW will dramatically reduce the capacitive coupling from SW into nearby traces To limit the trace resistance of the VBATT to inductor connection and from the inductor to SW connection, use short, wide traces (see Figure 58, Figure 59, and Figure 60). 11.1.4 Input Capacitor Selection and Placement The input bypass capacitor filters the inductor current ripple, and the internal MOSFET driver currents during turn on of the power switch. Submit Documentation Feedback Copyright © 2009–2014, Texas Instruments Incorporated Product Folder Links: LM3530 39 LM3530 SNVS606L – JUNE 2009 – REVISED DECEMBER 2014 www.ti.com Layout Guidelines (continued) The driver current requirement can range from 50 mA at 2.7 V to over 200 mA at 5.5 V with fast durations of approximately 10 ns to 20 ns. This will appear as high di/dt current pulses coming from the input capacitor each time the switch turns on. Close placement of the input capacitor to the IN pin and to the GND pin is critical since any series inductance between IN and CIN+ or CIN– and GND can create voltage spikes that could appear on the VIN supply line and in the GND plane. Close placement of the input bypass capacitor at the input side of the inductor is also critical. The source impedance (inductance and resistance) from the input supply, along with the input capacitor of the LM3530, form a series RLC circuit. If the output resistance from the source (RS) is low enough the circuit will be underdamped and will have a resonant frequency (typically the case). Depending on the size of LS the resonant frequency could occur below, close to, or above switching frequency of the device. This can cause the supply current ripple to be: 1. Approximately equal to the inductor current ripple when the resonant frequency occurs well above the LM3530 switching frequency; 2. Greater then the inductor current ripple when the resonant frequency occurs near the switching frequency; and 3. Less then the inductor current ripple when the resonant frequency occurs well below the switching frequency. Figure 57 shows the series RLC circuit formed from the output impedance of the supply and the input capacitor. The circuit is re-drawn for the AC case where the VIN supply is replaced with a short to GND and the LM3530 + Inductor is replaced with a current source (ΔIL). In Figure 57 below, 1. = the criteria for an underdamped response. 2. = the resonant frequency, and 3. = the approximated supply current ripple as a function of LS, RS, and CIN. As an example, consider a 3.6-V supply with 0.1-Ω of series resistance connected to CIN through 50 nH of connecting traces. This results in an underdamped input filter circuit with a resonant frequency of 712 kHz. Since the switching frequency lies near to the resonant frequency of the input RLC network, the supply current is probably larger then the inductor current ripple. In this case using Equation 2 from Figure 57 the supply current ripple can be approximated as 1.68 multiplied by the inductor current ripple. Increasing the series inductance (LS) to 500 nH causes the resonant frequency to move to around 225 kHz and the supple current ripple to be approximately 0.25 multiplied by the inductor current ripple. 40 Submit Documentation Feedback Copyright © 2009–2014, Texas Instruments Incorporated Product Folder Links: LM3530 LM3530 www.ti.com SNVS606L – JUNE 2009 – REVISED DECEMBER 2014 Layout Guidelines (continued) 'IL ISUPPLY RS L LS SW IN + LM3530 CIN - VIN Supply ISUPPLY RS LS 'IL CIN 2 1. RS 1 > L S x C IN 4 x L S2 2. f RESONANT = 3. 1 2S LS x CIN 1 2S x 500 kHz x CIN I SUPPLYRIPPLE | ' I L x § ¨ © 2 RS ¨2S x 500 kHz x L S - · ¸ 2S x 500 kHz x CIN ¸¹ 1 2 Figure 57. Input RLC Network 11.2 Layout Example Figure 58, Figure 59, and Figure 60 show example layouts which apply the required proper layout guidelines. These figures should be used as guides for laying out the LM3530 circuit. Figure 58. Layout Example 1 Submit Documentation Feedback Copyright © 2009–2014, Texas Instruments Incorporated Product Folder Links: LM3530 41 LM3530 SNVS606L – JUNE 2009 – REVISED DECEMBER 2014 www.ti.com Layout Example (continued) Figure 59. Layout Example 2 Figure 60. Layout Example 3 42 Submit Documentation Feedback Copyright © 2009–2014, Texas Instruments Incorporated Product Folder Links: LM3530 LM3530 www.ti.com SNVS606L – JUNE 2009 – REVISED DECEMBER 2014 12 Device and Documentation Support 12.1 Device Support 12.1.1 Third-Party Products Disclaimer TI'S PUBLICATION OF INFORMATION REGARDING THIRD-PARTY PRODUCTS OR SERVICES DOES NOT CONSTITUTE AN ENDORSEMENT REGARDING THE SUITABILITY OF SUCH PRODUCTS OR SERVICES OR A WARRANTY, REPRESENTATION OR ENDORSEMENT OF SUCH PRODUCTS OR SERVICES, EITHER ALONE OR IN COMBINATION WITH ANY TI PRODUCT OR SERVICE. 12.2 Documentation Support 12.2.1 Related Documentation For related documentation, see the following: Texas Instruments Application Note 1112: DSBGA Wafer Level Chip Scale Package (SNVA009). 12.3 Trademarks All trademarks are the property of their respective owners. 12.4 Electrostatic Discharge Caution This integrated circuit can be damaged by ESD. Texas Instruments recommends that all integrated circuits be handled with appropriate precautions. Failure to observe proper handling and installation procedures can cause damage. ESD damage can range from subtle performance degradation to complete device failure. Precision integrated circuits may be more susceptible to damage because very small parametric changes could cause the device not to meet its published specifications. 12.5 Glossary SLYZ022 — TI Glossary. This glossary lists and explains terms, acronyms, and definitions. 13 Mechanical, Packaging, and Orderable Information The following pages include mechanical, packaging, and orderable information. This information is the most current data available for the designated devices. This data is subject to change without notice and revision of this document. For browser-based versions of this data sheet, refer to the left-hand navigation. Submit Documentation Feedback Copyright © 2009–2014, Texas Instruments Incorporated Product Folder Links: LM3530 43 PACKAGE OPTION ADDENDUM www.ti.com 25-Sep-2014 PACKAGING INFORMATION Orderable Device Status (1) Package Type Package Pins Package Drawing Qty Eco Plan Lead/Ball Finish MSL Peak Temp (2) (6) (3) Op Temp (°C) Device Marking (4/5) LM3530TME-40/NOPB ACTIVE DSBGA YFQ 12 250 Green (RoHS & no Sb/Br) SNAGCU Level-1-260C-UNLIM DX LM3530TMX-40/NOPB ACTIVE DSBGA YFQ 12 3000 Green (RoHS & no Sb/Br) SNAGCU Level-1-260C-UNLIM DX LM3530UME-25A/NOPB ACTIVE DSBGA YFZ 12 250 Green (RoHS & no Sb/Br) SNAGCU Level-1-260C-UNLIM -30 to 85 DS LM3530UME-40/NOPB ACTIVE DSBGA YFZ 12 250 Green (RoHS & no Sb/Br) SNAGCU Level-1-260C-UNLIM -30 to 85 40 LM3530UME-40B/NOPB ACTIVE DSBGA YFZ 12 250 Green (RoHS & no Sb/Br) SNAGCU Level-1-260C-UNLIM LM3530UMX-25A/NOPB ACTIVE DSBGA YFZ 12 3000 Green (RoHS & no Sb/Br) SNAGCU Level-1-260C-UNLIM -30 to 85 DS LM3530UMX-40/NOPB ACTIVE DSBGA YFZ 12 3000 Green (RoHS & no Sb/Br) SNAGCU Level-1-260C-UNLIM -30 to 85 40 LM3530UMX-40B/NOPB ACTIVE DSBGA YFZ 12 3000 Green (RoHS & no Sb/Br) SNAGCU Level-1-260C-UNLIM DT DT (1) The marketing status values are defined as follows: ACTIVE: Product device recommended for new designs. LIFEBUY: TI has announced that the device will be discontinued, and a lifetime-buy period is in effect. NRND: Not recommended for new designs. Device is in production to support existing customers, but TI does not recommend using this part in a new design. PREVIEW: Device has been announced but is not in production. Samples may or may not be available. OBSOLETE: TI has discontinued the production of the device. (2) Eco Plan - The planned eco-friendly classification: Pb-Free (RoHS), Pb-Free (RoHS Exempt), or Green (RoHS & no Sb/Br) - please check http://www.ti.com/productcontent for the latest availability information and additional product content details. TBD: The Pb-Free/Green conversion plan has not been defined. Pb-Free (RoHS): TI's terms "Lead-Free" or "Pb-Free" mean semiconductor products that are compatible with the current RoHS requirements for all 6 substances, including the requirement that lead not exceed 0.1% by weight in homogeneous materials. Where designed to be soldered at high temperatures, TI Pb-Free products are suitable for use in specified lead-free processes. Pb-Free (RoHS Exempt): This component has a RoHS exemption for either 1) lead-based flip-chip solder bumps used between the die and package, or 2) lead-based die adhesive used between the die and leadframe. The component is otherwise considered Pb-Free (RoHS compatible) as defined above. Green (RoHS & no Sb/Br): TI defines "Green" to mean Pb-Free (RoHS compatible), and free of Bromine (Br) and Antimony (Sb) based flame retardants (Br or Sb do not exceed 0.1% by weight in homogeneous material) (3) MSL, Peak Temp. - The Moisture Sensitivity Level rating according to the JEDEC industry standard classifications, and peak solder temperature. Addendum-Page 1 Samples PACKAGE OPTION ADDENDUM www.ti.com (4) 25-Sep-2014 There may be additional marking, which relates to the logo, the lot trace code information, or the environmental category on the device. (5) Multiple Device Markings will be inside parentheses. Only one Device Marking contained in parentheses and separated by a "~" will appear on a device. If a line is indented then it is a continuation of the previous line and the two combined represent the entire Device Marking for that device. (6) Lead/Ball Finish - Orderable Devices may have multiple material finish options. Finish options are separated by a vertical ruled line. Lead/Ball Finish values may wrap to two lines if the finish value exceeds the maximum column width. Important Information and Disclaimer:The information provided on this page represents TI's knowledge and belief as of the date that it is provided. TI bases its knowledge and belief on information provided by third parties, and makes no representation or warranty as to the accuracy of such information. Efforts are underway to better integrate information from third parties. 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Addendum-Page 2 PACKAGE MATERIALS INFORMATION www.ti.com 16-Mar-2015 TAPE AND REEL INFORMATION *All dimensions are nominal Device Package Package Pins Type Drawing SPQ Reel Reel A0 Diameter Width (mm) (mm) W1 (mm) LM3530TME-40/NOPB DSBGA YFQ 12 250 178.0 8.4 B0 (mm) K0 (mm) P1 (mm) W Pin1 (mm) Quadrant 1.35 1.75 0.76 4.0 8.0 Q1 LM3530TMX-40/NOPB DSBGA YFQ 12 3000 178.0 8.4 1.35 1.75 0.76 4.0 8.0 Q1 LM3530UME-25A/NOPB DSBGA YFZ 12 250 178.0 8.4 1.37 1.77 0.56 4.0 8.0 Q1 LM3530UME-40/NOPB DSBGA YFZ 12 250 178.0 8.4 1.37 1.77 0.56 4.0 8.0 Q1 LM3530UME-40B/NOPB DSBGA YFZ 12 250 178.0 8.4 1.37 1.77 0.56 4.0 8.0 Q1 LM3530UMX-25A/NOPB DSBGA YFZ 12 3000 178.0 8.4 1.37 1.77 0.56 4.0 8.0 Q1 LM3530UMX-40/NOPB DSBGA YFZ 12 3000 178.0 8.4 1.37 1.77 0.56 4.0 8.0 Q1 LM3530UMX-40B/NOPB DSBGA YFZ 12 3000 178.0 8.4 1.37 1.77 0.56 4.0 8.0 Q1 Pack Materials-Page 1 PACKAGE MATERIALS INFORMATION www.ti.com 16-Mar-2015 *All dimensions are nominal Device Package Type Package Drawing Pins SPQ Length (mm) Width (mm) Height (mm) LM3530TME-40/NOPB DSBGA YFQ LM3530TMX-40/NOPB DSBGA YFQ 12 250 210.0 185.0 35.0 12 3000 210.0 185.0 35.0 LM3530UME-25A/NOPB DSBGA LM3530UME-40/NOPB DSBGA YFZ 12 250 210.0 185.0 35.0 YFZ 12 250 210.0 185.0 LM3530UME-40B/NOPB 35.0 DSBGA YFZ 12 250 210.0 185.0 35.0 LM3530UMX-25A/NOPB DSBGA YFZ 12 3000 210.0 185.0 35.0 LM3530UMX-40/NOPB DSBGA YFZ 12 3000 210.0 185.0 35.0 LM3530UMX-40B/NOPB DSBGA YFZ 12 3000 210.0 185.0 35.0 Pack Materials-Page 2 MECHANICAL DATA YFQ0012xxx D 0.600 ±0.075 E TMD12XXX (Rev B) D: Max = 1.64 mm, Min = 1.58 mm E: Max = 1.24 mm, Min = 1.18 mm 4215079/A NOTES: A. All linear dimensions are in millimeters. Dimensioning and tolerancing per ASME Y14.5M-1994. B. This drawing is subject to change without notice. www.ti.com 12/12 MECHANICAL DATA YFZ0012xxx D 0.425 ±0.045 E UMD12XXX (Rev A) D: Max = 1.64 mm, Min = 1.58 mm E: Max = 1.24 mm, Min = 1.18 mm 4215133/A NOTES: A. All linear dimensions are in millimeters. Dimensioning and tolerancing per ASME Y14.5M-1994. B. This drawing is subject to change without notice. www.ti.com 12/12 IMPORTANT NOTICE Texas Instruments Incorporated and its subsidiaries (TI) reserve the right to make corrections, enhancements, improvements and other changes to its semiconductor products and services per JESD46, latest issue, and to discontinue any product or service per JESD48, latest issue. Buyers should obtain the latest relevant information before placing orders and should verify that such information is current and complete. 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