DATA SHEET AAT2893 CABC Compatible, Ambient Light Control Boost LED Backlight Driver and Four LDOs General Description Features The AAT2893 family is a highly-integrated lighting management unit (LMU) optimized for single-cell lithium-ion/ polymer battery powered systems and is ideal for portable devices. WLED Driver The AAT2893 integrates a high voltage DC/DC boost converter and an internally programmed over-voltage protection circuit. It drives 10 LEDs (or more) in series1 controlled by a high precision, 128-step current sink, programmable up to 28.6mA. The high frequency PWM dimming implementation is compliant with Content Adaptive Brightness Control (CABC) specification with a PWM frequency up to 100kHz. The ambient light sensor (ALS) management function features automatic sensor calibration, enabling system designers to use low cost photo diodes, and 50Hz/60Hz noise rejection for accurate brightness adjustment without processor intervention. The AAT2893 also contains four high-performance, lownoise and low dropout (LDO) linear regulators. Each regulator starts up with a default 1.2V and is adjustable by programming through the I2C interface. LDOA can supply up to 300mA, while LDOB, C and D can source up to 150mA to a system load. All AAT2893 functions are programmed using an industry standard bi-directional I2C interface. The AAT2893 is available in a Pb-free, space saving 2.0mm x 2.5mm, 20-ball CSP package rated over a -40°C to +85°C temperature range. • 1.3MHz Switching Frequency • Over-voltage Protection ▪ AAT2893-1 up to 42V ▪ AAT2893-2 up to 33V • Automatic Soft Start • Programmable Backlight Current ▪ 28.6mA Maximum Current ▪ 128 Levels (7-bit): 0 – 28.6mA ▪ Programmable Fade-in and Fade-out • Advanced Dimming Features ▪ Ambient Light Sensor Management ▪ Direct Ambient Dimming Function - 128 Programmable Levels ▪ CABC Compatible PWM Dimming Four Linear Regulators ▪ LDOA up to 300mA ▪ LDOB, LDOC and LDOD up to 150mA ▪ 150mV Dropout ▪I2C Programmable Outputs: 1.2V to 3.3V ▪ Output Auto-Discharge for Fast Shutdown • Input Voltage Range: 3.0V to 5.5V • Built-In Over-temperature Protection • Industry Standard I2C Programming Interface • -40°C to 85°C Temperature Range • 2.0mm x 2.5mm, 20 Ball, 0.4mm Pitch CSP Package Applications • Camera Enabled Mobile Devices • Digital Still Cameras • Multimedia Mobile Phones Part Number I2C Address2 Over-voltage Protection Level (V) AAT2893-1 AAT2893-2 60h 60h 42 33 1. The actual number of series LEDs depends on OVP and VF of WLED. 2. Other I2C addresses available, contact factory. Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com 202075B • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • September 4, 2012 1 DATA SHEET AAT2893 CABC Compatible, Ambient Light Control Boost LED Backlight Driver and Four LDOs Typical Application Circuit DS1 L1 VOUT Backlight 4.7μH VBAT 3.6V CIN 4.7μF COUT 0.1μF LX IN OUT IN_LDO CIN_LDO 2.2μF Enable EN I2C Data Input SDA 2 I C Clock Input SCL PWM Control Input CCOMP 56nF CFLTR 10nF CSBIAS 2.2μF AAT2893 ILED PWM LDOA COMP LDOB VLDOB 150mA FLTR 2 AMB _IN AGND CLDOA 4.7μF 2.2μF SBIAS LDOC External Ambient Light Sensor (Photo Diode ) VLDOA 300mA LDOD PGND CLDOD 2.2μF VLDOD 150mA VLDOC 150mA CLDOC 2.2μF Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com 202075B • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • September 4, 2012 DATA SHEET AAT2893 CABC Compatible, Ambient Light Control Boost LED Backlight Driver and Four LDOs Pin Descriptions Pin # Symbol A1 LDOD A2 LDOC A3 LDOB A4 LDOA B1 IN_LDO B2 IN B3 EN B4 SBIAS C1 C2 C3 AGND DGND SCL C4 AMB_IN D1 D2 D3 D4 E1 E2 PGND PWM SDA FLTR LX OUT E3 ILED E4 COMP Description LDOD regulated voltage output pin. Bypass LDOD to AGND with a 2.2μF or larger capacitor as close to the AAT2893 as possible. LDOC regulated voltage output pin. Bypass LDOC to AGND with a 2.2μF or larger capacitor as close to the AAT2893 as possible. LDOB regulated voltage output pin. Bypass LDOB to AGND with a 2.2μF or greater capacitor as close to the AAT2893 as possible. LDOA regulated voltage output pin. Bypass LDOA to AGND with a 4.7μF or larger ceramic capacitor as close to the AAT2893 as possible. Input power supply pin for all four LDO voltage regulators. Bypass IN_LDO to PGND with a 2.2μF or larger ceramic capacitor located as close to the AAT2893 as possible. Power input. Connect IN to the input source voltage. Bypass IN to PGND with a 4.7μF or larger ceramic capacitor as close to the AAT2893 as possible. Enable Pin. Drive high to enable, low to shutdown. Ambient light sensor bias supply output. This pin provides a regulated bias supply to the attached ambient light sensor. Analog ground. Connect AGND to PGND at a single point as close to the AAT2893 as possible. Digital ground. Connect AGND and DGND and PGND at a single point as close to the AAT2893 as possible. I2C Serial Clock input pin Ambient light sensor input connection pin. Connect the photo diode anode or ambient light sensor module output to this pin. Power ground. Connect AGND to PGND at a single point as close to the AAT2893 as possible. Content controlled backlight brightness PWM signal input pin. Pull high to disable the PWM dimming feature. I2C Serial Data pin, this pin is bi-directional. PWM input filter capacitor pin. Connect a 10nF ceramic capacitor between this pin and AGND. Boost converter switching node. Connect a inductor between this node and IN. Boost converter output, place an external schottky between this node and LX Series LED string current sink. ILED controls the current through backlight LED constant current sink. Connect to the cathode of the last LED in the LED string. Compensation pin. Connect a capacitor via this pin to GND. Compensation components are mainly related to the output capacitor value. Pin Configurations 2.0mm × 2.5mm, 4 × 5 Ball Array CSP (Top View) 1 2 3 4 A LDOD LDOC LDOB LDOA B IN_LDO IN EN SBIAS C AGND DGND SCL AMB_IN D PGND PWM SDA FLTR E LX OUT ILED COMP Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com 202075B • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • September 4, 2012 3 DATA SHEET AAT2893 CABC Compatible, Ambient Light Control Boost LED Backlight Driver and Four LDOs Absolute Maximum Ratings1 Symbol Description VIN, VIN_LDO Input Voltage to AGND, PGND VLX, VILED, VOUT High Voltage to AGND, PGND EN, SDA, SCL, COMP, PWM, FLTR, SBIAS, LDOA, LDOB, LDOC, LDOD VAMB-IN Value Units -0.3 to 6 -0.3 to 50 -0.3 to 44 AAT2893-1 AAT2893-2 V Pin Voltage to AGND, PGND -0.3 to VIN+0.3 Ambient Light Sensor Maximum Input Voltage to AGND, PGND VIN Thermal Information2 Symbol ΘJA PD TJ TLEAD Description Thermal Resistance Maximum Power Dissipation Operating Junction Temperature Range Maximum Soldering Temperature (at Leads, 10s) 3 Value Units 79 1.26 -40 to 150 300 °C/W W °C Recommended Operating Conditions Symbol Description VIN VOUT L1 fPWM-F TA Input Supply Voltage Boost Converter Output Voltage Inductor Value Filtered PWM Input Frequency Ambient Operating Temperature Value Min 3.0 VIN+3V 4.7 0.1 -40 Typ Max 10 5.5 VOVP_T 22 100 85 25 Units V µH kHz °C 1. Stresses above those listed in Absolute Maximum Ratings may cause permanent damage to the device. Functional operation at conditions other than the operating conditions specified is not implied. 2. Mounted on a FR4 circuit board. 3. Derate 12.6mW/°C above 25°C ambient temperature. 4 Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com 202075B • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • September 4, 2012 DATA SHEET AAT2893 CABC Compatible, Ambient Light Control Boost LED Backlight Driver and Four LDOs Electrical Characteristics1 VIN = 3.6V; CIN = 4.7μF; CCOMP = 56nF; COUT = CSBIAS = 2.2µF; L = 4.7μH; TA = -40°C to +85°C, unless otherwise noted. Typical values are TA = 25°C. Symbol Description Boost Converter Input Operating VIN Voltage Range IN Operating Current Standby / No IQIN Load IQIN(SW) IN Operating Current (Switching) IIN(SHDN) IN Shutdown Current Over-temperature Shutdown TSD Threshold Over-Temperature Shutdown TSD(HYS) Hysteresis DMIN Minimum PWM dimming Duty Cycle DC/DC Boost Section RDS(ON) Switch On-Resistance η Maximum Efficiency fOSC Switching Frequency tss Soft-start Time DMAX Maximum Duty Cycle IL_LIMIT Inductor Current Limit OUT Over Voltage Protection VOVP_T Threshold VOVPH Over Voltage Protection Hysteresis Conditions Min Typ Max Units 5.5 V 3.0 EN = VIN; ILED = OFF via I2C 400 µA EN = VIN; No Load / ILED = ON EN = 0; ILED = OFF via I2C 2.3 1.0 150 15 TA = 25°C L1 = 10µH, IOUT = 28.6mA, VOUT = 36V TA = 25°C TA = 25°C 1.17 VOVP Rising 38 30.4 AAT2893-1 AAT2893-2 °C 8 % 650 82 1.3 4 mΩ % MHz ms % mA 1.43 94 AAT2893-1 AAT2893-2 mA µA 800 42 33 2.8 2.2 45 36 V ILED Driver IILED ILED Current Accuracy tFADE ILED Automatic Fade In/Out Timer Ambient Light Sensor Interface Ambient Light Sensor Bias Voltage VSBIAS Output Tolerance IOUT(SBIAS)[MAX] SBIAS Maximum Output Current Ambient Light Sensor Full Scale VALS(FS) Input Voltage IIN(ALS)[MAX] ALS ADC maximum input current ROUT(SBIAS)[DCHG] SBIAS Auto-Discharge Resistance VIN – VF = 1V, Set ILED = 19.8mA by I2C VIN – VF = 1V, Set ILED = 2.03mA by I2C VIN – VF = 1V 17.8 1.62 0.75 19.8 2.03 1 21.79 2.43 1.25 mA mA s Set VSBIAS = 3.0V by I2C, ISBIAS = 200µA Set VSBIAS = 2.6V by I2C, ISBIAS = 200µA 2.85 2.47 30 3.0 2.60 3.15 2.73 V mA 1.6 V 1 1 µA kΩ 1. The AAT2893 is guaranteed to meet performance specifications over the -40°C to +85°C operating temperature range and is assured by design, characterization, and correlation with statistical process controls. 2. Current matching is defined as the deviation of any sink current from the average of all active channels. 3.VDO[A/B/C/D] is defined as VIN – LDO[A/B/C/D] when LDO[A/B/C/D] is 98% of nominal. Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com 202075B • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • September 4, 2012 5 DATA SHEET AAT2893 CABC Compatible, Ambient Light Control Boost LED Backlight Driver and Four LDOs Electrical Characteristics (continued)1 VIN = 3.6V; CIN = 4.7μF; CCOMP = 56nF; COUT = CSBIAS = 2.2µF; L = 4.7μH; TA = -40°C to +85°C, unless otherwise noted. Typical values are TA = 25°C. Symbol Description Conditions Min Typ Max Units 5.5 V 2 3.0 % Linear Regulators VIN_LDO ΔVOUT[A/B/C,D]/ VOUT[A/B/C,D] IOUT[A](MAX) VOUT[A](DO) IOUT[B/C,D](MAX) VOUT[B/C,D](DO) ∆VOUT/ (VOUT · ∆VIN) LDOA, LDOB, LDOC, LDOD Output Voltage Tolerance LDOA Maximum Load Current LDOA Dropout Voltage3 LDOB, LDOC, LDOD Maximum Load Current LDOB, LDOC, LDOD Dropout Voltage3 IOUT = 1mA to 150mA; TA = 25°C IOUT = 1mA to 150mA; TA = -40°C to +85°C VOUT[B/C/D] ≥ 3.0V; IOUT = 150mA 150 mV Line Regulation VIN = (VOUT[A/B/C/D] + 1V) to 5V 0.09 %/V 50 dB 1 kΩ LDOA, LDOB, LDOC, LDOD Power Supply Rejection Ratio LDOA, LDOB, LDOC, LDOD AutoROUT_(DCHG) Discharge Resistance Input Threshold Levels - EN, PWM VTH(L) Input Low Threshold VTH(H) Input High Threshold I2C Logic and Control Interface VIL SDA, SCL, EN Input Low Threshold VIH SDA, SCL, EN Input High Threshold VOL SDA Output Low Voltage IIN SDA, SCL, EN Input Leakage Current fSCL SCL Clock Frequency tLOW SCL Clock Low Period tHIGH SCL Clock High Period tHD_STA Hold Time START Condition tSU_DAT SDA Data Setup Time tHD_DAT SDA Data HOLD Time tSU_STO Setup Time for STOP Condition Bus Free Time Between STOP and tBUF START Conditions PSRR[A/B/C,D] VOUT + VDO LDO Regulator Input Supply -2 -3.0 300 VOUT[A] ≥ 3.0V; IOUT = 300mA mA mV 200 150 IOUT[A/B/C/D] = 10mA, 1kHz mA 0.4 1.4 3.0V ≤ VIN ≤ 5.5V 3.0V ≤ VIN ≤ 5.5V IPULLUP = 3mA VSDA = VSCL V 0.4 1.4 -1 0 1.3 0.6 0.6 100 0 0.6 V 0.4 1 400 µA kHz µs ns 0.9 µs 1.3 1. The AAT2893 is guaranteed to meet performance specifications over the -40°C to +85°C operating temperature range and is assured by design, characterization, and correlation with statistical process controls. 6 Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com 202075B • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • September 4, 2012 DATA SHEET AAT2893 CABC Compatible, Ambient Light Control Boost LED Backlight Driver and Four LDOs I2C Interface Timing Details SDA t SU_DAT t LOW t HD_STA t BUF SCL t HD_STA t HD_DAT t HIGH t SU_STA t SU_STO Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com 202075B • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • September 4, 2012 7 DATA SHEET AAT2893 CABC Compatible, Ambient Light Control Boost LED Backlight Driver and Four LDOs Typical Characteristics IQ vs Supply Voltage IQ vs Supply Voltage (Enable LDO, Disable LED via I2C, ILDO = 0) 640 640 580 580 520 520 460 460 IQ (µA) IQ (µA) (LED = OFF , Disable LDO via I2C) 400 340 400 340 280 25°C 280 220 -40°C 220 -40°C 160 85°C 160 85°C 100 3 3.3 3.6 3.9 4.2 4.5 4.8 5.1 100 5.4 Supply Voltage (V) LED Current (mA) LED Current (mA) 30 28 27 26 10 35 60 3.9 4.2 4.5 4.8 5.1 29 28 27 26 -15 10 35 60 85 Temperature (°C) Shutdown Current vs Temperature LED Current vs Register (Addr. 00h) Code (4.7µH , 10 WLEDs) (VIN = 3.6V , EN = GND) 30 0.8 25 LED Current (mA) 1 0.6 0.4 0.2 0 20 15 VIN = 3.0V VIN = 3.6V 10 VIN = 4.2V VIN = 5.0V 5 VIN = 5.5V -0.2 -40 -15 10 35 Temperature (°C) 8 60 5.4 (AAT2893-1, VIN = 3.6V, ILED = 28.6mA, 10 WLEDs) 25 -40 85 Temperature (°C) ISHUTDOWN (µA) 3.6 LED Current vs Temperature 29 -15 3.3 Supply Voltage (V) (AAT2893-2, VIN = 3.6V, ILED = 28.6mA, 8 WLEDs) 25 -40 3 LED Current vs Temperature 30 25°C 0 85 0 10 20 30 40 50 60 70 80 90 100 110 120 Register (Addr. 00h) Code Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com 202075B • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • September 4, 2012 DATA SHEET AAT2893 CABC Compatible, Ambient Light Control Boost LED Backlight Driver and Four LDOs Typical Characteristics PWM Duty vs LED Current PWM Duty vs LED Current (AAT2893-2 10 WLEDs) 30 30 25 25 LED Current (mA) LED Current (mA) (AAT2893-1 10 WLEDs) 20 15 VIN = 3.0V VIN = 3.6V 10 VIN = 4.2V VIN = 5.0V 5 0 20 15 VIN = 3.0 VIN = 3.6 10 VIN = 4.2 VIN = 5.0 5 VIN = 5.5V VIN = 5.5 0 0 10 20 30 40 50 60 70 80 90 100 PWM Duty (%) 0 50 60 70 80 90 100 (AAT2893-2, ILED = 28.6mA , 8 WLEDs) 30 LED Current (mA) LED Current (mA) 40 LED Current vs Supply Voltage 30 29 28 25C 27 -40C 85C 3 3.5 4 4.5 5 29.2 28.4 27.6 25°C 26.8 26 5.5 Supply Voltage (V) -40°C 85°C 3 80 75 75 Efficiency (%) 80 70 65 55 VIN = 3.6V 50 VIN = 4.2V VIN = 5.0V 5 10 15 20 LED Current (mA) 25 70 65 60 VIN = 3.0V 55 VIN = 3.6V 50 VIN = 4.2V VIN = 5.0V 45 VIN = 5.5V 0 5.5 (AAT2893-2, 8 WLEDs) 85 VIN = 3.0V 5 4.5 Efficiency vs LED Current 85 60 4 Supply Voltage (V) (AAT2893-1, 10 WLEDs) 45 3.5 Efficiency vs LED Current Efficiency (%) 30 PWM Duty (%) (AAT2893-1, ILED = 28.6mA , 10 WLEDs) 40 20 LED Current vs Supply Voltage 26 10 40 30 VIN = 5.5V 0 5 10 15 20 25 30 LED Current (mA) Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com 202075B • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • September 4, 2012 9 DATA SHEET AAT2893 CABC Compatible, Ambient Light Control Boost LED Backlight Driver and Four LDOs Typical Characteristics Efficiency vs Register Dimming Code (Addr. 00h) (4.7µH , 10LEDs) 90 2.7 Under-Voltage Lockout Thresholds vs Temperature VIN Rising UVLO Threshold (V) 80 Efficiency (%) 70 60 50 VIN = 3.0V 40 VIN = 3.6V 30 VIN = 4.2V 20 VIN = 5.0V 10 0 VIN = 5.5V 0 5 10 15 20 25 30 Register Dimming Code (Addr.00h) 2.3 2.1 1.9 1.7 -40 Frequency (MHz) Frequency (MHz) 1.40 1.30 1.25 10 35 60 35 60 (AAT2893-1, VIN = 3.6V, ILED = 28.6mA, 10 WLEDs) 1.35 1.30 1.25 1.20 -40 85 Temperature (°C) -15 10 35 60 Enable Threshold vs Temperature (VIN = 3.6V) 1.4 1.4 EN_High Enable Threshold (V) Enable Threshold (V) EN_High EN_Low 1.2 1 0.8 0.6 3 3.3 3.6 3.9 4.2 4.5 Voltage (V) 10 85 Temperature (°C) Enable Threshold vs Supply Voltage 0.4 2.7 85 Frequency vs Temperature 1.35 -15 10 Temperature (°C) (AAT2893-2, VIN = 3.6V, ILED = 28.6mA, 8 WLEDs) 1.20 -40 -15 Frequency vs Temperature 1.40 VIN Falling 2.5 4.8 5.1 5.4 1 0.8 0.6 0.4 -40 5.7 EN_Low 1.2 -15 10 35 60 Temperature (°C) Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com 202075B • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • September 4, 2012 85 DATA SHEET AAT2893 CABC Compatible, Ambient Light Control Boost LED Backlight Driver and Four LDOs Typical Characteristics OVP vs Temperature Boost Switch-On Resistance vs Temperature (VIN = 3.6V, LED Open) Switch-On Resistance (mΩ) OVP Protection (V) 45 44 43 42 41 40 39 38 -40 -15 10 35 60 85 Temperature (°C) (VIN = 3.6V ) 900 800 700 600 500 400 300 -40 -15 10 35 60 85 Temperature (°C) ALS Read Data vs IAMB_IN in Low Gain Mode Addr08h (AMLRB) Read Data (Gain Resistor = 4kΩ, VIN = 3.6V) 120 110 100 90 80 70 60 50 40 30 20 10 0 Addr07 = 01 Addr07 = 02 Addr07 = 03 Addr07 = 04 Addr07 = 05 Addr07 = 06 Addr07 = 07 Addr07 = 08 Addr07 = 09 Addr07 = 10 Addr07 = 11 Addr07 = 12 Addr07 = 13 Addr07 = 14 Addr07 = 15 Addr07 = 00 0 100 200 300 400 500 600 700 800 900 1000 IAMB_IN (µA) LDOB/C/D Dropout Voltage vs Load LDOB/C/D Dropout Voltage (mV) LDOA Dropout Voltage (mV) LDOA Dropout Voltage vs Load 200 160 120 80 VOUT = 2.5V 40 VOUT = 3.0V VOUT = 3.3V 0 0 30 60 90 120 150 Load Current (mA) 180 210 240 200 160 120 80 VOUT = 2.5V 40 0 VOUT = 3.0V VOUT = 3.3V 0 30 60 90 120 150 Load Current (mA) Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com 202075B • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • September 4, 2012 11 DATA SHEET AAT2893 CABC Compatible, Ambient Light Control Boost LED Backlight Driver and Four LDOs Typical Characteristics VLDOA Accuracy vs Temperature VLDOB/C/D Accuracy vs Temperature 2.0 VLDOB/C/D Accuracy (%) VLDOA Accuracy (%) 2.0 1.2 0.4 -0.4 -1.2 VOUT = 1.2V 1.2 0.4 -0.4 VOUT = 1.2V -1.2 VOUT = 3.3V VOUT = 3.3V -2.0 -40 -15 10 35 60 -2.0 85 Temperature (°C) -40 85 0.800 Load Regulation (%) Load Regulation (%) 60 (VIN = 3.6V , VLDOA = 3.3V) 0.800 0.400 0.000 -0.400 0.400 0.000 -0.400 1 10 100 -0.800 1 1000 Load Current (mA) 1000 (VIN = 3.6V , VLDOB/C/D = 3.3V) 0.800 0.400 0.000 -0.400 -0.800 1 100 LDOB/C/D Output Voltage Load Regulation (VIN = 3.6V , VLDOB/C/D = 1.2V) Load Regulation (%) 0.800 10 Load Current (mA) LDOB/C/D Output Voltage Load Regulation Load Regulation (%) 35 LDOA Output Voltage Load Regulation (VIN = 3.6V , VLDOA = 1.2V) 0.400 0.000 -0.400 10 100 Load Current (mA) 12 10 Temperature (°C) LDOA Output Voltage Load Regulation -0.800 -15 -0.800 1 1000 10 100 Load Current (mA) Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com 202075B • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • September 4, 2012 1000 DATA SHEET AAT2893 CABC Compatible, Ambient Light Control Boost LED Backlight Driver and Four LDOs Typical Characteristics Switching Operation Switching Operation (AAT2893-1, VIN = 3.6V, ILED = 19.8mA, 10 WLEDs) (AAT2893-2, VIN = 3.6V, ILED = 19.8mA, 8 WLEDs) VLX VLX 0V 20V/div 20V/div 0V VOUT(AC) VOUT(AC) 100mV/div 50mV/div IL IL 500mA/div 500mA/div 0A 0A I LED(AC) I LED (AC) 2mA/div 2mA/div Time (500ns/div) Time (500ns/div) OVP Boost Start Up (AAT2893-1, VIN = 3.6V, ILED = 28.6mA, 10WLEDs) (VIN = 3.6V, Open LED) VSDA 5V VOUT 3V 4V/div VLX 20V/div 3.6V VOUT(AC) 20V/div 42V 5V/div VLX VIN(AC) ILED 3.6V 20V/div 50mV/div 0mA 20mA/div Time (10ms/div) Time (10ms/div) PWM Dimming Switching PWM Dimming Switching (VIN = 3.6V, Duty Cycle = 30%, ILED = 19.8mA) (VIN = 3.6V, Duty Cycle = 80%, ILED = 19.8mA) PWM PWM 2V/div 2V/div 0V VOUT(AC) VOUT(AC) VLX VLX ILED (AC) 1mA/div ILED(AC) 1mA/div 0V 50mV/div 50mV/div 20V/div 20V/div Time (50µs/div) Time (50µs/div) Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com 202075B • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • September 4, 2012 13 DATA SHEET AAT2893 CABC Compatible, Ambient Light Control Boost LED Backlight Driver and Four LDOs Typical Characteristics Fade Out Characteristics Fade In Characteristics (AAT2893-1 VIN = 3.6V, ILED = 18.9mA, 10 WLEDs, Fade Time = 1s, Fade Floor Current = 0.45mA) VSDA 2V/div VOUT (AAT2893-1 VIN = 3.6V, ILED = 18.9mA, 10WLEDs, Fade Time = 1s, Fade Floor Current = 0.45mA) VSDA 5V 2V/div 26V ILED 5V/div 10mA/div Time (200ms/div) Time (200ms/div) LDO StartUp LDO Output Voltage Change (VIN = 3.6V, ILDO = 20mA, VLDO convert from 1.2V to 3.3V via I2C) (VIN = 3.6V, VLDO = 2.5V, ILDO = 20mA) 0V VSDA VOUT 0V 1V/div 1V/div Time (50µs/div) Time (50µs/div) LDOA Line Transient LDOB/C/D Line Transient (VIN = 3.6V ~ 5.5V, VLDOB/C/D = 2.5V, ILDOB/C/D = 20mA) VIN 3.6V VLDOA VLDOB/C/D 2.5V 50mV/div Time (100µs/div) 14 3.6V 1V/div 1V/div 50mV/div 1.2V (VIN = 3.6V ~ 5.5V, VLDOA = 2.5V, ILDOA = 20mA) VIN 0V 2V/div 2V/div VOUT 19.8mA ILED 0.45mA 10mA/div VSDA 31.3V VOUT 5V/div 5V 2.5V Time (100µs/div) Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com 202075B • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • September 4, 2012 DATA SHEET AAT2893 CABC Compatible, Ambient Light Control Boost LED Backlight Driver and Four LDOs Typical Characteristics LDOA Load Transient LDOB/C/D Load Transient (VIN = 3.6V, ILDOB/C/D = 1mA~150mA, VLDOB/C/D = 2.5V) (VIN = 3.6V, ILDOA= 1mA~300mA, VLDOA = 2.5V) 2.5V VLDOB/C/D VLDOA 50mV/div 50mV/div ILDOA 100mA/div 2.5V ILDOB/C/D 0mA 100mA/div Time (100µs/div) 0mA Time (100µs/div) Cross Talk between LDOA and LDOB/C/D (VIN = 3.6V, ILDOB/C/D = 1mA~150mA, VLDOA = VLDOB/C/D = 2.5V) ILDOB/C/D (100mA/div) 0mA VLDOB/C/D 2.5V VLDOA 2.5V 50mV/div 10mV/div Time (100µs/div) Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com 202075B • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • September 4, 2012 15 DATA SHEET AAT2893 CABC Compatible, Ambient Light Control Boost LED Backlight Driver and Four LDOs Functional Block Diagram PGND AMB _IN OUT DC/DC Boost Converter Control IN SBIAS LX OVP LDO Regulator Oscillator Programmable Amplifier + ADC Backlight Current Control EN PWM FLTR COMP Control Logic REF SDA SCL I2C Interface LDOA 300mA LDOA LDOB 150mA LDOB LDOC 150mA LDOC LDOD 150mA LDOD Over Temperature Monitor IN_LDO AGND Functional Description The AAT2893 integrates a high voltage DC/DC boost converter and an internally programmed over-voltage protection circuit. It drives up to 10 backlight LEDs in series from a 3.0V to 5.5V input voltage source. To reduce overall power consumption, the AAT2893 supports CABC by providing high frequency filtered PWM for content based dimming and automatic ambient light sensing for varying lighting conditions. The ambient light control (ALC) includes a regulated bias supply to power an ALS or a photo diode. The integrated ADC polls the 16 ILED PGND ambient light conditions and is readable through the I2C interface. The ambient light control (ALC) can also be configured to automatically adjust backlight brightness for changing ambient lighting conditions. LED Driver The AAT2893 is capable of driving up to 10 backlight LEDs in series with 128 programmable constant current levels up to 28.6mA. The inductive DC/DC boost converter operates at a high, 1.3MHz switching frequency allowing the use of small external 1.0μF-4.7μF ceramic Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com 202075B • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • September 4, 2012 DATA SHEET AAT2893 CABC Compatible, Ambient Light Control Boost LED Backlight Driver and Four LDOs capacitors and requiring a 4.7µH-22µH inductor. The output of the DC/DC boost converter is controlled by the voltage across the LED current sink when programmed for a desired LED forward current. An over-voltage protection feedback is provided to prevent damage to the LED string or system when an over-voltage event occurs at the output of the boost converter. LED Current Control The backlight LED string constant current level is controlled through the I2C interface. The backlight LED current can be set between 0mA and 28.6mA in steps of approximately 0.23mA. All backlight LED functions including fading, ambient light control and constant current levels are programmed through the I2C interface. Ambient Light Sensing The AAT2893 ALC circuit provides an interface and control for external ambient light sensor module or photo diode. The system incorporates a programmable sensor voltage bias supply (SBIAS) which may be configured to output 3.0V, 2.8V, 2.7V or 2.6V and may source up to 30mA. The ALS input has a programmable gain amplifier and ADC. The current ambient light level data can be read through the I2C interface for other system functions. When the ALC is enabled to directly adjust the backlight, the 16 internal registers with pre-configured backlight dimming levels are used to profile 16 different ambient lighting conditions. To save power and improve system efficiency, the ALC circuit features manual polling and automatic polling with programmable polling times. Under polling control, the SBIAS regulator, ambient light sensor and ADC circuit are disabled and only enabled for a short period to sample and store the present ambient light value in the ALS digital output read register. The ADC continuously filters out the 50Hz and 60Hz flicker noise from indoor lighting, eliminating the need for a large capacitor at the output pin of the ambient light sensor. interface. Additionally, the I2C interface allows the LDO regulators to be enabled independently for any combination of output voltages. The LDO regulators require a small 2.2μF (LDOB/C/D) and a 4.7μF (LDOA) ceramic output capacitor for maximized performance and stability. If improved load transient response is required, larger value capacitors can be used without stability degradation. Serial Programmed Registers The AAT2893 has 28 registers listed in Table 1: • Four for backlight enable, control and configuration of fade in/out function • Twenty-one for ambient light sensor control and configuration and • Three for LDOs control and configuration. Backlight Current Programming The backlight string current is disabled by default. The backlight current can be easily configured by using ILED (00h) registers. LED string needs to be enabled by setting BL_EN=1 from BL_ENBLS (01h) register. The current default setting is 19.8mA. Fade In/Fade Out Programming The fade in/out function allows LEDs to fade between two programmed current levels in a smooth, logarithmic progression. By default, fade in/out is enabled (bits FADE_EN and FADE_INIT have a default value of 1). The fade in/out function can be disabled by writing FADE_EN =0 in FADE (03h) register. The fade function can be interrupted by writing the FADE_EN bit to 0 when a fade event is in progress. When this happens, the current will abruptly change to the ceiling value programmed in BL<7:0> bits in ILED register. The duration of the fade in/out sequences can be programmed by setting FTIME<1:0> in FADE register. The default fade in/out timing is 1s. LDO Regulators Fade In Function The AAT2893 includes four low dropout (LDO) linear regulators. These regulators are programmable through the I2C interface. LDOA is designed to provide load current up to 300mA, and LDOB, C and D are intended for loads up to 150mA respectively. The output voltage of each LDO can be set to one of 16 levels between 1.2V and 3.3V. The LDO regulators turn on/off and regulate output voltage level by programming through the I2C At initial start up, the LED string turns on with a default value of 19.8mA per channel unless fade in has been specifically programmed. The lower current (floor) is programmed using FLR[3:0] bits in FADE_FLR register. The default is 0.45mA per channel. The higher current (ceiling) is programmed using bits BL [6:0] in ILED (00h) register. Fade in sequence is initiated when FADE_ INIT is changed from 0 to 1 in FADE (03h) register. Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com 202075B • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • September 4, 2012 17 DATA SHEET AAT2893 CABC Compatible, Ambient Light Control Boost LED Backlight Driver and Four LDOs Fade Out Function The fade out sequence is initiated when FADE_INIT is changed from 1 to 0 in FADE (03h) register. The floor current will persist until LED string is disabled by writing BL_EN=1 to BL_ENBLS (01h) register. I2C Serial Interface Protocol The AAT2893 uses an I2C serial interface to set backlight LED current, LDO on/off and output voltage, as well as other housekeeping functions. The AAT2893 acts only as a slave device. The I2C protocol uses two open-drain inputs: SDA (serial data line) and SCL (serial clock line). Both inputs require an external pull up resistor, typically start msb Chip Address lsb w ack msb to the input voltage. The I2C protocol is bidirectional. The timing diagram in Figure 1 shows the typical I2C interface protocol. Devices on the I2C bus can either be a master or a slave. Both master and slave devices can send and receive data over the bus, the difference being that the master device controls all communication on the bus. The I2C communications begin by the master making a START condition. Next the master transmits the 7-bit device address and a Read/Write bit. Each slave device on the bus has a unique address. The AAT2893's 7-bit device address is 0x60. Register Address lsb ack msb Register Data lsb ack stop SCL SDA start AAT2893 Device Address Id = 60h w ack Addr = 0 0 h ack Address = 00h Data = 06h ack First Byte Writes as 0xC0 Figure 1: Typical I2C Timing Diagram. 18 Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com 202075B • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • September 4, 2012 stop DATA SHEET AAT2893 CABC Compatible, Ambient Light Control Boost LED Backlight Driver and Four LDOs START and STOP Conditions the SCL line low. A START condition acts as a signal to devices on the bus that the device producing the START condition is active and will be communicating on the bus. START and STOP conditions are always generated by the master. Prior to initiating a START, both the SDA and SCL pin are inactive and are pulled high through external pullup resistors. As shown in Figure 2, a START condition occurs when the master pulls the SDA line low and, after the start condition hold time (tHT_STA), the master strobes A STOP condition, as shown in Figure 2, occurs when SCL changes from low to high followed after the STOP condition setup time (tSU_STO), by an SDA low-to-high transition. The master does not issue an ACK but releases SCL and SDA. STOP START SDA SDA SCL SCL tSU_STO tHD_STA Figure 2: I2C STOP and START Conditions; START: A High “1” to Low “0” Transition on the SDA Line While SCL is High “1” STOP: A Low “0” to High “1” Transition on the SDA Line While SCL is High “1”. Transferring Data device transmits an ACK signal to indicate that it has received the transmission. The ACK signal is generated by the target after the master releases the SDA data line by driving SDA low. Addresses and data are sent with the most significant bit first transmitted and the least significant bit transmitted last. After each address or data transmission, the target SCL 1 2 3 4 5 6 7 MSB SDA A6 8 9 LSB A5 A4 A3 A2 A1 A0 R/W ACK Device Address Figure 3: I2C Address Bit Map; 7-bit Slave Address (A6-A0), 1-bit Read/Write (R/W), 1-bit Acknowledge (ACK). SCL 1 2 3 4 5 6 7 MSB SDA D7 8 9 LSB D6 D5 D4 D3 D2 D1 D0 ACK Register Address / Data Figure 4: I2C Register Address and Data Bit Map; 8-bit Data (D7-D0), 1-bit Acknowledge (ACK). Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com 202075B • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • September 4, 2012 19 DATA SHEET AAT2893 CABC Compatible, Ambient Light Control Boost LED Backlight Driver and Four LDOs Writing to Slave Device When the Read/Write bit is set to 0 and the address transmitted by the master matches the slave device’s address, the slave device transmits an Acknowledge (ACK) signal to indicate that it is ready to receive data. Next, the master transmits the 8-bit register address, start msb Chip Address lsb w ack msb and the slave device transmits an ACK to indicate that it received the register address. After that, the master transmits the 8-bit data word, and again the slave device transmits an ACK indicating that it received the data. This process continues until the master finishes writing to the slave device at which time the master generates a STOP condition. Register Address lsb ack msb Register Data lsb ack stop SCL SDA start AAT2893 Device Address Id = 60h w ack Addr = 0 0 h ack Address = 00h Data = 06h ack stop First Byte Writes as 0xC0 Figure 5: AAT2893 I2C Write Timing Diagram. Reading from Slave Device When the Read/Write bit is set to 1 and the address transmitted by the master matches the slave device’s address, the slave device transmits an Acknowledge (ACK) signal to indicate that it is ready to receive data. start msb Chip Address lsb AAT2893 Device Address Id = 60h w ack r ack Next, the slave device transmits the 8-bit data word, and the master reads the data byte and transmits an Acknowledge ACK to indicate that it received the byte, and generates a STOP condition. msb Register Data lsb stop ack SCL SDA start Data = 0 8 h ack stop First Byte Writes as 0xC1 Figure 6: AAT2893 I2C Read Timing Diagram. 20 Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com 202075B • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • September 4, 2012 DATA SHEET AAT2893 CABC Compatible, Ambient Light Control Boost LED Backlight Driver and Four LDOs Serial Programmed Registers The AAT2893's I2C programming registers are listed in Table 1. Register Hex Code Function Bit7 Bit6 Bit5 Bit4 Bit3 Bit2 Bit1 Bit0 Figures 00h Backlight LED Current 0 BL[6] BL[5] BL[4] BL[3] BL[2] BL[1] BL[0] Figure.7 01h BL & CABC Enables 0 0 0 0 0 0 BL_EN CABC_EN Figure.8 02h Fade Floor 0 0 0 0 FLR[3] FLR[2] FLR[1] FLR[0] Figure.9 FADE 03h Fade Control FTIME[1] FTIME[0] FADE_EN INIT_FADE Figure.10 ALC_ FADE 04h ALC Fade Time ALCFU[1] ALCFU[0] ALCFD[1] ALCFD[0] Figure.11 ALS_ CFG0 05h ALS Functions PMODE RSET[2] RSET[1] RSET[0] GAIN[1] GAIN[0] GM_SEL ALS_EN Figure.12 ALS_ CFG1 06h SBIAS ON/OFF OFF_TM OS_ ADJ[3] OS_ ADJ[2] OS_ ADJ[1] OS_ADJ[0] SB[1] SB[0] SB_EN Figure.13 ALS_ CFG2 07h ALS input gain/offset SNSR ALSOUT PTIME[1] PTIME[0] G_ADJ[3] G_ADJ[2] G_ADJ[1] G_ADJ[0] Figure.14 AMLRB 08h Ambient Level (Read) AMB[7] AMB[6] AMB[5] AMB[4] AMB[3] AMB[2] AMB[1] AMB[0] Figure.15 ALS_BL0 09h ALS Data ALS0[6] ALS0[5] ALS0[4] ALS0[3] ALS0[2] ALS0[1] ALS0[0] ALS_BL1 0Ah ALS Data ALS1[6] ALS1[5] ALS1[4] ALS1[3] ALS1[2] ALS1[1] ALS1[0] ALS_BL2 0Bh ALS Data ALS2[6] ALS2[5] ALS2[4] ALS2[3] ALS2[2] ALS2[1] ALS2[0] ALS_BL3 0Ch ALS Data ALS3[6] ALS3[5] ALS3[4] ALS3[3] ALS3[2] ALS3[1] ALS3[0] ALS_BL4 0Dh ALS Data ALS4[6] ALS4[5] ALS4[4] ALS4[3] ALS4[2] ALS4[1] ALS4[0] ALS_BL5 0Eh ALS Data ALS5[6] ALS5[5] ALS5[4] ALS5[3] ALS5[2] ALS5[1] ALS5[0] ALS_BL6 0Fh ALS Data ALS6[6] ALS6[5] ALS6[4] ALS6[3] ALS6[2] ALS6[1] ALS6[0] ALS_BL7 10h ALS Data ALS7[6] ALS7[5] ALS7[4] ALS7[3] ALS7[2] ALS7[1] ALS7[0] ALS_BL8 11h ALS Data ALS8[6] ALS8[5] ALS8[4] ALS8[3] ALS8[2] ALS8[1] ALS8[0] ALS_BL9 12h ALS Data ALS9[6] ALS9[5] ALS9[4] ALS9[3] ALS9[2] ALS9[1] ALS9[0] ALS_BLA 13h ALS Data ALSA[6] ALSA[5] ALSA[4] ALSA[3] ALSA[2] ALSA[1] ALSA[0] ALS_BLB 14h ALS Data ALSB[6] ALSB[5] ALSB[4] ALSB[3] ALSB[2] ALSB[1] ALSB[0] ALS_BLC 15h ALS Data ALSC[6] ALSC[5] ALSC[4] ALSC[3] ALSC[2] ALSC[1] ALSC[0] ALS_ BLD 16h ALS Data ALSD[6] ALSD[5] ALSD[4] ALSD[3] ALSD[2] ALSD[1] ALSD[0] ALS_BLE 17h ALS Data ALSE[6] ALSE[5] ALSE[4] ALSE[3] ALSE[2] ALSE[1] ALSE[0] ALS_BLF 18h ALS Data ALSF[6] ALSF[5] ALSF[4] ALSF[3] ALSF[2] ALSF[1] ALSF[0] LDO_AB 19h LDO Select LDOA[3] LDOA[2] LDOA[1] LDOA[0] LDOB[3] LDOB[2] LDOB[1] LDOB[0] Figure.17 LDO_CD 1Ah LDO Select LDOC[3] LDOC[2] LDOC[1] LDOC[0] LDOD[3] LDOD[2] LDOD[1] LDOD[0] Figure.18 LDO_EN 1Bh LDO Enable 0 0 0 0 LDO_END LDO_ENC LDO_ENB LDO_ENA Figure.19 Name ILED BL_ENBLS FADE_ FLR Figure.16 Table 1: AAT2893 Register Map. (“0” must be written 0; "blank" = Unassigned). Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com 202075B • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • September 4, 2012 21 DATA SHEET AAT2893 CABC Compatible, Ambient Light Control Boost LED Backlight Driver and Four LDOs ILED: Backlight LED Current Control Register (Address 00h, Default 58h) U-0 W-1 W-0 W-1 W-1 W-0 W-0 W-0 -- BL[6] BL[5] BL[4] BL[3] BL[2] BL[1] BL[0] Bit 7 Bit 0 Bit 7 Unassigned Bit 6 – Bit 0 BL<6:0>: Backlight LED Current Magnitude 0000000 0000001 0000010 0000011 0000100 0000101 0000110 0000111 0001000 0001001 0001010 0001011 0001100 0001101 0001110 0001111 0010000 0010001 0010010 0010011 0010100 0010101 0010110 0010111 0011000 0011001 0011010 0011011 0011100 0011101 0011110 0011111 0100000 0100001 0100010 0100011 0100100 0100101 0100110 0100111 0101000 0101001 0101010 0101011 = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = 0.00 0.23 0.45 0.68 0.90 1.13 1.35 1.58 1.80 2.03 2.25 2.48 2.70 2.93 3.15 3.38 3.60 3.83 4.05 4.28 4.50 4.73 4.95 5.18 5.40 5.63 5.85 6.08 6.30 6.53 6.75 6.98 7.20 7.43 7.65 7.87 8.10 8.32 8.55 8.77 9.00 9.22 9.45 9.67 mA mA mA mA mA mA mA mA mA mA mA mA mA mA mA mA mA mA mA mA mA mA mA mA mA mA mA mA mA mA mA mA mA mA mA mA mA mA mA mA mA mA mA mA 0101100 0101101 0101110 0101111 0110000 0110001 0110010 0110011 0110100 0110101 0110110 0110111 0111000 0111001 0111010 0111011 0111100 0111101 0111110 0111111 1000000 1000001 1000010 1000011 1000100 1000101 1000110 1000111 1001000 1001001 1001010 1001011 1001100 1001101 1001110 1001111 1010000 1010001 1010010 1010011 1010100 1010101 1010110 1010111 = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = 9.90 mA 10.13 mA 10.35 mA 10.58 mA 10.80 mA 11.03 mA 11.25 mA 11.48 mA 11.70 mA 11.93 mA 12.15 mA 12.38 mA 12.60 mA 12.83 mA 13.05 mA 13.28 mA 13.50 mA 13.73 mA 13.95 mA 14.18 mA 14.40 mA 14.63 mA 14.85 mA 15.08 mA 15.30 mA 15.53 mA 15.75 mA 15.98 mA 16.20 mA 16.43 mA 16.65 mA 16.88 mA 17.10 mA 17.33 mA 17.55 mA 17.78 mA 18.00 mA 18.23 mA 18.45 mA 18.68 mA 18.90 mA 19.13 mA 19.35 mA 19.58 mA 1011000 1011001 1011010 1011011 1011100 1011101 1011110 1011111 1100000 1100001 1100010 1100011 1100100 1100101 1100110 1100111 1101000 1101001 1101010 1101011 1101100 1101101 1101110 1101111 1110000 1110001 1110010 1110011 1110100 1110101 1110110 1110111 1111000 1111001 1111010 1111011 1111100 1111101 1111110 1111111 = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = = 19.80 20.03 20.25 20.48 20.70 20.93 21.15 21.38 21.60 21.83 22.05 22.28 22.50 22.73 22.95 23.18 23.40 23.63 23.85 24.08 24.30 24.53 24.75 24.98 25.20 25.43 25.65 25.88 26.10 26.33 26.55 26.78 27.00 27.23 27.45 27.68 27.90 28.13 28.35 28.58 mA mA mA mA mA mA mA mA mA mA mA mA mA mA mA mA mA mA mA mA mA mA mA mA mA mA mA mA mA mA mA mA mA mA mA mA mA mA mA mA Legend: R = Readable bit -v = Default value W = Writeable bit ‘1’ = Bit is set U = Unassigned n = Channel number ‘0’ = Bit is cleared x = Bit is unknown Figure 7: Backlight Current Control Register. 22 Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com 202075B • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • September 4, 2012 DATA SHEET AAT2893 CABC Compatible, Ambient Light Control Boost LED Backlight Driver and Four LDOs BL_ENBLS: Backlight & CABC Enable Register (Address 01h Default 00h) U-0 U-0 U-0 U-0 U-0 U-0 -- -- -- -- -- -- W-0 W-0 BL_EN CABC_EN Bit 7 Bit 0 Bit 7 – Bit 2 Unassigned Bit 1 BL_EN: Backlight Enable Register 0 = Backlight channel is disabled 1 = Backlight channel is enabled Bit 0 CABC_EN: CABC PWM Input Enable Register 0 = PWM Input is active 1 = PWM Input is inactive (operating at maximum duty cycle) Legend: R = Readable bit -v = Default value W = Writeable bit ‘1’ = Bit is set U = Unassigned n = Channel number ‘0’ = Bit is cleared x = Bit is unknown Figure 8: Backlight and CABC Enable Register. Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com 202075B • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • September 4, 2012 23 DATA SHEET AAT2893 CABC Compatible, Ambient Light Control Boost LED Backlight Driver and Four LDOs FADE_FLR: Fade In/ Out Floor Levels Register (Address 02h Default 00h) U-0 U-0 U-0 U-0 W-0 W-0 W-0 W-0 -- -- -- -- FLR[3] FLR[2] FLR[1] FLR[0] Bit 7 Bit 0 Bit 7 – Bit 4 Unassigned Bit 3 – Bit 0 FLR<3:0>: Fade In/Out Floor Levels 0000 = 0.45 mA 0001 = 0.90 mA 0010 = 1.80 mA 0011 = 2.70 mA 0100 = 3.60 mA 0101 = 4.50 mA 0110 = 5.40 mA 0111 = 6.30 mA 1000 = 7.20 mA 1001 = 8.10 mA 1010 = 9.00 mA 1011 = 9.90 mA 1100 = 10.8 mA 1101 = 11.7 mA 1110 = 12.6 mA 1111 = 13.5 mA Legend: R = Readable bit -v = Default value W = Writeable bit ‘1’ = Bit is set U = Unassigned n = Channel number ‘0’ = Bit is cleared x = Bit is unknown Figure 9: Backlight Fade In/Out Level Register. 24 Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com 202075B • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • September 4, 2012 DATA SHEET AAT2893 CABC Compatible, Ambient Light Control Boost LED Backlight Driver and Four LDOs FADE: Fade In/ Out Control Register (Address 03h Default 03h) U-0 U-0 U-0 U-0 W-0 -- -- -- -- FTIME[1] W-0 W-1 W-1 FTIME[0] FADE_EN INIT_FADE Bit 7 Bit 0 Bit 7 – Bit 4 Unassigned Bit 3 – Bit 2 FTIME<1:0>: Fade In/Out Timing 00 01 10 11 = = = = 1.0 0.8 0.6 0.4 sec sec sec sec FADE_EN: Fade In/Out Enable Bit 1 0 = Fade in/out is enabled for backlight group 1 = Fade in/out is disabled for backlight group INIT_FADE: Fade In/Out Initiation Bit 0 0 = Fade out is initiated for backlight group 1 = Fade in is initiated for backlight group Legend: R = Readable bit -v = Default value W = Writeable bit ‘1’ = Bit is set U = Unassigned n = Current Sink number ‘0’ = Bit is cleared x = Bit is unknown Figure 10: Backlight Fade In/Out Time and Enable Control Register. Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com 202075B • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • September 4, 2012 25 DATA SHEET AAT2893 CABC Compatible, Ambient Light Control Boost LED Backlight Driver and Four LDOs ALC_FADE: Ambient Light Control Fade up/down Time and Rate Register (Address 04h Default 0Bh) U-0 U-0 U-0 U-0 -- -- -- -- W-1 W-0 W-1 W-1 ALCFU[1] ALCFU[0] ALCFD[1] ALCFD[0] Bit 7 Bit 0 Bit 7 – Bit 4 Unassigned Bit 3 – Bit 2 ALCFU<1:0>: Ambient Light Control Fade Up Time and Rate Register 00 = Fade Up Time is 100ms, Fade Up Rate is 0.8ms/step 01 = Fade Up Time is 200ms, Fade Up Rate is 1.6ms/step 10 = Fade Up Time is 400ms, Fade Up Rate is 3.1ms/step 11 = Fade Up Time is 800ms, Fade Up Rate is 6.3ms/step Bit 1 – Bit 0 ALCFD<1:0>: Ambient Light Control Fade Down Time and Rate Register 00 = Fade Down Time is 50ms, Fade Down Rate is 0.4ms/step 01 = Fade Down Time is 100ms, Fade Down Rate is 0.8ms/step 10 = Fade Down Time is 200ms, Fade Down Rate is 1.6ms/step 11 = Fade Down Time is 400ms, Fade Down Rate is 3.1ms/step Legend: R = Readable bit -v = Default value W = Writeable bit ‘1’ = Bit is set U = Unassigned n = Current Sink number ‘0’ = Bit is cleared x = Bit is unknown Figure 11: ALS Fade Up/Down Time and Rate Register. 26 Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com 202075B • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • September 4, 2012 DATA SHEET AAT2893 CABC Compatible, Ambient Light Control Boost LED Backlight Driver and Four LDOs ALS_CFG0: Ambient Light Sensor Input Gain Adjustment and Enable Register (Address 05h Default 10h) W-0 W-0 W-0 W-1 W-0 W-0 W-0 W-0 PMODE RSET[2] RSET[1] RSET[0] GAIN[1] GAIN[0] GM_SEL ALS_EN Bit 7 Bit 0 PMODE: Ambient Light Sensor (ALS) Input Gain Polling Mode Selection Bit 7 0 = Automatic polling mode 1 = Manual polling mode RSET<2:0>: Ambient Light Sensor (ALS) Set Resistor Selection Bit 6 – Bit 4 000 001 010 011 = = = = 500Ω, 2kΩ 1kΩ, 4kΩ 2kΩ, 8kΩ 4kΩ, 16kΩ 100 = 8kΩ, 32kΩ 101 = 16kΩ, 64kΩ 110 = Reserved 111 = Reserved GAIN<1:0>: Ambient Light Sensor (ALS) Input Amplifier Gain Mode Selection Bit 3 – Bit 2 00 = Low gain mode 01 = High gain mode 1X = Fixed gain mode (External Resistor Required) Bit 1 GM_SEL: Ambient Light Sensor (ALS) Gain Mode Selection 0 = Auto gain mode 1 = Manual gain mode Bit 0 ALS_EN: Ambient Light Sensor (ALS) Enable 0 = Disable ambient light sensor 1 = Enable ambient light sensor Legend: R = Readable bit -v = Default value W = Writeable bit ‘1’ = Bit is set U = Unassigned n = Current Sink number ‘0’ = Bit is cleared x = Bit is unknown Figure 12: ALS Gain Selection and Enable Register. Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com 202075B • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • September 4, 2012 27 DATA SHEET AAT2893 CABC Compatible, Ambient Light Control Boost LED Backlight Driver and Four LDOs ALS_CFG1: Ambient Light Sensor (ALS) Voltage Bias Control Register (Address 06h Default 06h) W-0 OFF_TM W-0 W-0 W-0 W-0 OS_ADJ[3] OS_ADJ[2] OS_ADJ[1] OS_ADJ[0] W-1 W-1 W-0 SB[1] SB[0] SB_EN Bit 7 Bit 0 OFF_TM: Ambient Light Sensor (ALS) Bias Offset Test Mode Enable Bit 7 0 = Bias offset test mode disable 1 = Bias offset test mode enable Bit 6 – Bit 3 OS_ADJ<3:0>: Ambient Light Sensor (ALS) Bias Offset Adjustment 0000 0001 0010 0011 0100 0101 0110 0111 1000 1001 1010 1011 1100 1101 1110 1111 Bit 2 – Bit 1 = = = = = = = = = = = = = = = = No Adjustment +1 LSB +2 LSB +3 LSB +4 LSB +5 LSB +6 LSB +7 LSB -8 LSB -7 LSB -6 LSB -5 LSB -4 LSB -3 LSB -2 LSB -1 LSB SB<1:0>: SBIAS Output Voltage Level Selection 00 01 10 11 = = = = 3.0 2.8 2.7 2.6 V V V V EN_SBIAS: SBIAS Output Enable Bit 0 0 = Disable SBIAS output 1 = Enable SBIAS output Legend: R = Readable bit -v = Default value W = Writeable bit ‘1’ = Bit is set U = Unassigned n = Current Sink number ‘0’ = Bit is cleared x = Bit is unknown Figure 13: ALS Voltage Bias and Offset Calibration Register 28 Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com 202075B • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • September 4, 2012 DATA SHEET AAT2893 CABC Compatible, Ambient Light Control Boost LED Backlight Driver and Four LDOs ALS_CFG2: Ambient Light Sensor (ALS) Input Gain Adjustment Register (Address 07h Default 00h) W-0 W-0 SNSR W-0 W-0 W-0 W-0 W-0 W-0 ALSOUT PTIME[1] PTIME[0] G_ADJ[3] G_ADJ[2] G_ADJ[1]G_ADJ[0] Bit 7 Bit 0 SNSR: Ambient Light Sensor (ALS) Linear or Logarithmic Sensor Output Selection Bit 7 0 = Linear sensor output 1 = Logarithmic sensor output ALSOUT: Ambient Light Sensor (ALS) Linear or Logarithmic Backlight Brightness Selection Bit 6 0 = Linear backlight brightness 1 = Logarithmic backlight brightness PTIME<1:0>: Ambient Light Sensor (ALS) Input Gain Polling Time Selection Bit 5 – Bit 4 00 01 10 11 = = = = 0.5 1.0 1.5 2.0 sec sec sec sec G_ADJ<3:0>: Ambient Light Sensor (ALS) Input Gain Adjustment Selection Bit 3 – Bit 0 0000 0001 0010 0011 0100 0101 0110 0111 1000 1001 1010 1011 1100 1101 1110 = = = = = = = = = = = = = = = No Adjustment + 6.25% +12.50% +18.75% +25.00% +31.25% +37.50% +43.75% -50% -43.75% -37.50% -31.25% -25.00% -18.75% -12.50% 1111 = -6.25% Legend: R = Readable bit -v = Default value W = Writeable bit ‘1’ = Bit is set U = Unassigned n = Current Sink number ‘0’ = Bit is cleared x = Bit is unknown Figure 14: ALS Input Gain Adjustment and Polling Time Register. Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com 202075B • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • September 4, 2012 29 DATA SHEET AAT2893 CABC Compatible, Ambient Light Control Boost LED Backlight Driver and Four LDOs AMLRB: Ambient Light Sensor (ALS) Read Data Register (Address 08h Default 00h) R R AMB[7] AMB[6] R R R R R R AMB[5] AMB[4] AMB[3] AMB[2] AMB[1] AMB[0] Bit 7 Bit 0 AMB<7:0>: Ambient Light Sensor (ALS) Read Data Register Bit 7 – Bit 0 00000000 = 00 00000001 = 01 ……. ……. ……. 11111111 = 7F Legend: R = Readable bit -v = Default value W = Writeable bit ‘1’ = Bit is set U = Unassigned n = Current Sink number ‘0’ = Bit is cleared x = Bit is unknown Figure 15: ALS Digital Output Read Data Register. 30 Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com 202075B • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • September 4, 2012 DATA SHEET AAT2893 CABC Compatible, Ambient Light Control Boost LED Backlight Driver and Four LDOs ALS_BLn: Ambient Light Sensor (ALS) Backlight Current Level Programming Register (Address 09h – Address 18h Default 00h) W-0 U-0 -- W-0 W-0 ALSn[6] ALSn[5] ALSn[4] W-0 W-0 W-0 ALSn[3] ALSn[2] ALSn[1] ALSn[0] Bit 7 Bit 6 – Bit 0 W-0 Bit 0 ALSn<6:0>: Ambient Light Sensor (ALS) Backlight Current Level Programming LED Current (Log) 0000100 0000101 0000111 0001001 0001011 0001110 0010001 0010101 0011011 0100010 0101010 0110100 1000001 1010010 1100110 1111111 = = = = = = = = = = = = = = = = 0.00 0.10 0.19 0.29 0.39 0.49 0.58 0.68 0.78 0.88 0.97 1.07 1.17 1.26 1.36 1.46 LED Current (mA) 0.9 1.1 1.4 1.8 2.3 2.9 3.6 4.5 5.7 7.2 9.0 11.4 14.3 18.0 22.7 28.6 Brightness (Lux) 64 91 130 185 263 374 532 758 1079 1535 2185 3111 4428 6303 8971 12770 Legend: R = Readable bit -v = Default value W = Writeable bit ‘1’ = Bit is set U = Unassigned n = Current Sink number ‘0’ = Bit is cleared x = Bit is unknown Figure 16: ALS Controlled Current Dimming Levels Programming Register. Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com 202075B • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • September 4, 2012 31 DATA SHEET AAT2893 CABC Compatible, Ambient Light Control Boost LED Backlight Driver and Four LDOs LDO_AB: LDOA and LDOB Output Voltage Level Programming Register (Address 19h Default 00h) W-0 W-0 W-0 W-0 W-0 W-0 W-0 W-0 LDOA[3] LDOA[2] LDOA[1] LDOA[0] LDOB[3] LDOB[2] LDOB[1] LDOB[0] Bit 7 Bit 7 – Bit 4 Bit 0 LDOA<3:0>: LDOA Output Voltage Level Selection 0000 0001 0010 0011 0100 0101 0110 0111 1000 1001 1010 1011 1100 1101 1110 1111 Bit 3 – Bit 0 = = = = = = = = = = = = = = = = 1.2V 1.3V 1.5V 1.6V 1.8V 2.0V 2.2V 2.5V 2.6V 2.7V 2.8V 2.9V 3.0V 3.1V 3.2V 3.3V LDOB<3:0>: LDOB Output Voltage Level Selection 0000 0001 0010 0011 0100 0101 0110 0111 1000 1001 1010 1011 1100 1101 1110 1111 = = = = = = = = = = = = = = = = 1.2V 1.3V 1.5V 1.6V 1.8V 2.0V 2.2V 2.5V 2.6V 2.7V 2.8V 2.9V 3.0V 3.1V 3.2V 3.3V Legend: R = Readable bit -v = Default value W = Writeable bit ‘1’ = Bit is set U = Unassigned n = Current Sink number ‘0’ = Bit is cleared x = Bit is unknown Figure 17: LDOA/LDOB Output Voltage Level Programming Register. 32 Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com 202075B • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • September 4, 2012 DATA SHEET AAT2893 CABC Compatible, Ambient Light Control Boost LED Backlight Driver and Four LDOs LDO_CD: LDOC and LDOD Output Voltage Level Programming Register (Address 1Ah Default 00h) W-0 W-0 W-0 W-0 W-0 W-0 W-0 W-0 LDOC[3] LDOC[2] LDOC[1] LDOC[0] LDOD[3] LDOD[2] LDOD[1] LDOD[0] Bit 7 Bit 7 – Bit 4 Bit 0 LDOC<3:0>: LDOC Output Voltage Level Selection 0000 0001 0010 0011 0100 0101 0110 0111 1000 1001 1010 1011 1100 1101 1110 1111 Bit 3 – Bit 0 = = = = = = = = = = = = = = = = 1.2V 1.3V 1.5V 1.6V 1.8V 2.0V 2.2V 2.5V 2.6V 2.7V 2.8V 2.9V 3.0V 3.1V 3.2V 3.3V LDOD<3:0>: LDOD Output Voltage Level Selection 0000 0001 0010 0011 0100 0101 0110 0111 1000 1001 1010 1011 1100 1101 1110 1111 = = = = = = = = = = = = = = = = 1.2V 1.3V 1.5V 1.6V 1.8V 2.0V 2.2V 2.5V 2.6V 2.7V 2.8V 2.9V 3.0V 3.1V 3.2V 3.3V Legend: R = Readable bit -v = Default value W = Writeable bit ‘1’ = Bit is set U = Unassigned n = Current Sink number ‘0’ = Bit is cleared x = Bit is unknown Figure 18: LDOC/LDOD Output Voltage Level Programming Register. Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com 202075B • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • September 4, 2012 33 DATA SHEET AAT2893 CABC Compatible, Ambient Light Control Boost LED Backlight Driver and Four LDOs LDO_EN: LDOA/B/C/D Output Enable Register (Address 1Bh Default 00h) U-0 U-0 U-0 U-0 W-0 W-0 W-0 W-0 -- -- -- -- LDO_END LDO_ENC LDO_ENB LDO_ENA Bit 7 Bit 7 – Bit 5 Bit 4 Bit 0 Unassigned LDOD_END : LDOD Output Enable 0 = LDOD output is disabled 1 = LDOD output is enabled Bit 3 LDOD_ENC : LDOC Output Enable 0 = LDOC output is disabled 1 = LDOC output is enabled Bit 2 LDOD_ENB : LDOB Output Enable 0 = LDOB output is disabled 1 = LDOB output is enabled Bit 3 LDOD_ENA : LDOA Output Enable 0 = LDOA output is disabled 1 = LDOA output is enabled Legend: R = Readable bit -v = Default value W = Writeable bit ‘1’ = Bit is set U = Unassigned n = Current Sink number ‘0’ = Bit is cleared x = Bit is unknown Figure 19: LDO Output Enable Register. 34 Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com 202075B • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • September 4, 2012 DATA SHEET AAT2893 CABC Compatible, Ambient Light Control Boost LED Backlight Driver and Four LDOs Ambient Light Sensor (ALS) An ambient-light sensor is used to measure the brightness of the surrounding environment. Based on the brightness level, the AAT2893 can adjust the backlight LED current, leading to longer battery life and comfortable viewing with less eyestrain. The AAT2893 supports a wide range of sensors, presently on the market, and performs the gain-adjustment function to correct the part-to-part output variation of an ambient light sensor. Some typical values of the luminance in different environments are given below as reference points: • • • • • • Moonlight: 0.2 to 1 Lux Candlelight: 5 Lux Streetlight: 10 Lux Office light: 300 to 1000 Lux Daylight (not direct sun): 10,000 Lux Direct sunlight: 100,000 Lux Ambient light sensors used in smart phone applications are often placed underneath a light pipe and a glass cover. The actual light brightness reaching the ambient light sensor must be determined before choosing an ambient light sensor. Current (mA) Application Information Log r ea Lin Light Intensity (Lux) Figure 20: Ambient Light Sensor with Linear or Logarithmic Output Current. Ambient Light Sensor Evaluation Determine the Range of Light Brightness that Reaches Ambient Light Sensor (ALS) Determine the Type of Ambient Light Sensor (ALS)-Linear or Logarithmic Ambient Light Sensor Selection The types of ambient light sensors on the market include photodiodes, photo-transistors, and photo-ICs; all these types of sensors generate current or voltage output signals. Ambient light sensors with current outputs require a resistor placed at the output to convert the current into voltage. Figure 20 shows the current output, which is linear or logarithmic with the light brightness in Lux, of an ambient- light sensor. Some ambient light sensors provide logarithmic or square-root outputs. If an ambient light sensor with linear output is used while a logarithmic output is desired, the AAT2893 can convert a linear ALS output to logarithmic output by setting SNSR = 0 and setting ALSOUT = 1 in register ALS_CFG2(07h) as shown in Figure 14. Ambient Light Sensor Evaluation: 1. Select Gain resistor Set 2. Measure DC Offset 3. Select SBIAS Voltage 4. Determine the LED Current For Each Brightness Reading 5. Measure Gain Adjustment Determine the Backlight Brightness Measurement Mode-Linear or Logarithmic Determine the Polling Time and Mode – Automatic or Manual Figure 21: Ambient Light Sensor Configuration Flowchart. Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com 202075B • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • September 4, 2012 35 DATA SHEET AAT2893 CABC Compatible, Ambient Light Control Boost LED Backlight Driver and Four LDOs EN_ALS ADC Measurement 500ms for PTIME<1:0> =00 100 ms for 1st Sample SBIAS AMB<3:0> 200ms for Manual and Automatic Measurement with AMB_IN ≥ 0.4V (normal ambient brightness) 300ms for Automatic Measurement with AMB_IN < 0.4V (dim ambient brightness) Figure 22: Ambient Light Sensor A/D Conversion Timing Diagram. Ambient Light Sensor Gain Resistor Selection When an ambient light sensor with current output is selected, a load resistor is used to convert the output current into an output voltage. The AAT2893 provides a set of 6 internal resistor pairs that are listed in Figure 12. An external resistor can be used if none of the integrated resistor pairs fit the application requirement. Example 1: The light luminance of the ambient light sensor is from 0 Lux to 10,000 Lux. If the output current of an ambient light sensor is 4μA per 100Lux, the resistor required to cover the whole luminance range can be calculated as follows: Low-gain Resistor = VAMB_IN (MAX) 4µA ∙ 10000Lux 100Lux = 4kΩ The chosen resistor set is 4kΩ, 16kΩ. Ambient Light Sensor Offset Adjustment Any leakage current present will cause an offset at the output of the ambient light sensor, leading to inaccurate measurement of the light brightness. This offset can be corrected by programming bits OS_ADJ<3:0> in register ALS_CFG1 (06h) of the AAT2893. The four allocated bits provide offset correction from -8LSB to +7LSB, as shown in Figure 13. The DC offset of the ambient-light sensor output can be 36 measured with the AAT2893. The AAT2893 is powered up and enabled with a power supply or a battery; the ambient light sensor is then enabled by writing ALS_EN = 1 to the ALS_CFG0 (05h) register (see Figure 12). The voltage bias for the ambient light sensor needs to be enabled as well by writing SB_EN = 1 to the ALS_CFG1 (06h) register (see Figure 13). The test mode of the ambient light sensor offset commences when writing OFF_TM = 1 to the ALS_CFG1 (06h) register. Example 2: The procedure to determine the ambient light-sensor offset is explained below, assuming a resistor set of 4kΩ, 16kΩ is used: • Connect the SBIAS pin of the AAT2893 to the input voltage pin of an ambient light sensor, and connect the AMB_IN pin of AAT2893 to the output pin of the ambient- light sensor. • The BH1600FVC ambient light sensor from Rohm is used with the AAT2893 demo board (Figures 30 and 31). Depending on how much light goes through the light pipe and reaches the ambient light sensor, the GC1 and GC2 setting can be determined. If the range of light is up to 10,000 Lux, the L-Gain mode should be chosen by connecting GC1 to GND and GC2 to SBIAS. If the range of light is up to 3,000 Lux or lower, then the H-Gain mode should be chosen by connecting GC1 to SBIAS and GC2 to GND. The difference between H-Gain mode and L-Gain mode is the amount of output current from the ambient light sensor (see Table 6). Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com 202075B • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • September 4, 2012 DATA SHEET AAT2893 CABC Compatible, Ambient Light Control Boost LED Backlight Driver and Four LDOs • The AAT2893’s ambient light sensor amplifier is set to auto gain mode. The part will automatically choose the 4kΩ low-gain resistor when the ambient light is bright and the 16kΩ high-gain resistor when the ambient light is dim for better accuracy. • Set enable pin EN = High and PWM = High to enable the AAT2893. • Start ambient light sensor offset measurement by writing the following commands to the AAT2893: 1. Write AAT2893 7-bit I2C address: 0x60 (first byte writes as C0h, binary 11000000). 2. Enable backlight channel by writing to register BL_EN (01h) data 02h. 3. Choose linear ambient light sensor gain mode and internal gain resistor pair by writing to register ALS_CFG0 (05h) data 31h. 4. Enable SBIAS in offset test mode by writing to register ALS_CFG1 (06h) data 81h (Note: During normal operation, offset test-mode should be turned off by setting bit OFF_TM = 0 in ALS_CFG1 (06h) register as shown in Figure 13). • Read the AMB (08h) register for the ambient light sensor output offset. AMB register has eight bits, only bits AMB[7:3] should be captured; bit AMB[7] is a sign (+ or -) bit. • Convert the 5-bit in AMB(08h) register in test mode to a 4-bit offset according to Table 3. The 4-bit offset with opposite sign needs to be written to OS_ ADJ<3:0> from ALS_CFG1 (06h) register during normal operation. Note: If the 5-bit offset reading is F8h (binary 11111000), then the output offset of the ambient light sensor is -1LSB. It can be converted to 1111 in 4 bits. In order to adjust this ambient light sensor offset, a +1 LSB offset needs to be added, by writing 0001 to OS_ADJ<3:0> of the ALS_CFG1 (06h) register during normal operation. For complete list of offset adjustments see Table 2. ALS_CFG1: Ambient Light Sensor Voltage Bias and Offset Calibration Control Register ALS 4-Bit Offset Measurement in Test Mode OS_ ADJ[3] OS_ ADJ[2] OS_ ADJ[1] OS_ ADJ[0] Offset 0 0 0 0 0 0 0 0 0 0 0 0 1 1 1 1 0 1 0 1 0 1 0 1 0 +1 +2 +3 +4 +5 +6 +7 1 1 1 1 1 1 1 1 0 0 0 0 1 1 1 1 0 0 1 1 0 0 1 1 Offset too high 0 0 1 1 0 0 1 1 0 1 0 1 0 1 0 1 -8 -7 -6 -5 -4 -3 -2 -1 ALS 4-Bit Offset Adjustment in Normal Mode OS_ ADJ[3] OS_ ADJ[2] OS_ ADJ[1] OS_ ADJ[0] Offset 0 1 1 1 1 1 1 1 1 0 1 1 1 1 0 0 0 0 0 1 0 1 0 1 0 1 0 0 -1 -2 -3 -4 -5 -6 -7 -8 0 0 0 0 0 0 0 1 1 1 1 0 0 0 0 1 1 0 0 1 1 0 0 Offset too high 1 1 0 0 0 1 0 1 0 1 0 1 0 1 +7 +6 +5 +4 +3 +2 +1 Table 2: Ambient Light Sensor 4-Bit Offset Adjustment. Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com 202075B • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • September 4, 2012 37 DATA SHEET AAT2893 CABC Compatible, Ambient Light Control Boost LED Backlight Driver and Four LDOs AMB: Ambient Light Sensor Digital Output Read Data Register ALS_CFG1: Ambient Light Sensor Voltage Bias and Offset Calibration Register ALS 5-Bit Offset Measurement in Test Mode ALS 4-Bit Offset Measurement in Test Mode AMB[7] AMB[6] AMB[5] AMB[4] AMB[3] 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 0 0 0 0 0 0 0 0 1 1 1 1 1 1 1 1 0 0 0 0 0 0 0 0 1 1 1 1 1 1 1 1 0 0 0 0 1 1 1 1 0 0 0 0 1 1 1 1 0 0 0 0 1 1 1 1 0 0 0 0 1 1 1 1 0 0 1 1 0 0 1 1 0 0 1 1 0 0 1 1 0 0 1 1 0 0 1 1 0 0 1 1 0 0 1 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 OS_ ADJ[3] OS_ ADJ[2] OS_ ADJ[1] OS_ ADJ[0] Offset 0 0 0 0 0 0 0 0 0 0 0 0 1 1 1 1 0 0 1 1 0 0 1 1 0 1 0 1 0 1 0 1 0 +1 +2 +3 +4 +5 +6 +7 0 1 0 1 0 1 0 1 -8 -7 -6 -5 -4 -3 -2 -1 Offset too high 1 1 1 1 1 1 1 1 0 0 0 0 1 1 1 1 0 0 1 1 0 0 1 1 Table 3: Ambient Light Sensor 5-Bit to 4-Bit Offset Conversion. 38 Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com 202075B • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • September 4, 2012 DATA SHEET AAT2893 CABC Compatible, Ambient Light Control Boost LED Backlight Driver and Four LDOs Ambient Light Sensor Gain Adjustment For the majority of ambient light sensors, the part-topart variation of the output current is guaranteed to be ±20% at best. More expensive ambient light sensors can guarantee ±10% output accuracy. Tolerances in light pipes and ambient light sensors limit the output current accuracy to only ±35%. AAT2893 allows the customer to choose an inexpensive ambient light sensor while offering a ±10% part-to-part variation by providing an automatic calibration gain adjustment from -50% to +43.75% for any off-the-shelf ambient light sensor. Figure 23 shows the ideal ambient light sensor output versus light brightness after gain-adjustment calibration. Part 1 Current (mA) Ideal Part 2 The maximum AMB_IN input voltage is 2.4V with -37.5% gain adjustment. For optimal performance, the minimum output voltage of an ambient light sensor needs to be higher than the adjusted AMB_IN input voltage with an extra 6.25% headroom, or 2.55V according to Table 4. Ambient Light Sensor Voltage Bias The external ambient light sensor is powered by the SBIAS output, which is a programmable linear voltage regulator that provides up to 30mA for the sensor bias. The SBIAS output voltage may be programmed and enabled both by the ambient light sensor control register ALS_CFG0 (Figure 12) and the ambient light sensor voltage bias control register ALS_CFG1 (Figure 13). The SBIAS voltage can be selected from 2.6V up to 3V by writing bits SB<1:0> of the ALS_CFG1 (06h) register. The SBIAS voltage is determined based on the full-scale negative gain adjustment necessary to achieve optimal performance. The relationship between the AMB_IN ideal Full-Scale voltage (unadjsted Full-Scale), the gain adjustment (Gain_ADJ), and the adjusted AMB_ IN scale (Adjusted Full-Scale) can be expressed by the following equation: Adjusted Full-Scale = Light Intensity (Lux) Figure 23: Ambient Light Sensor Output Current with Gain Variation. Ideal Full-Scale 1 + Gain_ADJ The minimum saturated output voltage of the BH1600FVC ambient light sensor is 2.6V for 3.0V supply voltage; therefore, a SBIAS voltage of 3V should be selected for this particular case. If the calculated AMB_IN maximum voltage exceeds 3V, an external voltage source is recommended. Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com 202075B • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • September 4, 2012 39 DATA SHEET AAT2893 CABC Compatible, Ambient Light Control Boost LED Backlight Driver and Four LDOs G_ADJ[3:0] Gain Adjustment (%) AMB_IN Full Scale (V) ALS_CFG2 (07h) AMB_IN Min (V) AMB_IN Max (V) 0111 0110 0101 0100 0011 0010 0001 0000 1111 1110 1101 1100 1011 1010 1001 1000 43.75 37.50 31.25 25.00 18.75 12.50 6.25 0 -6.25 -12.5 -18.75 -25.00 -31.25 -37.50 -43.75 -50.00 1.11 1.16 1.22 1.28 1.35 1.42 1.51 1.60 1.71 1.83 1.97 2.13 2.33 2.56 2.84 3.20 07h 06h 05h 04h 03h 02h 01h 00h 0Fh 0Eh 0Dh 0Ch 0Bh 0Ah 09h 08h 1.04 1.09 1.14 1.20 1.26 1.33 1.41 1.50 1.60 1.71 1.85 2.00 2.18 2.40 2.67 3.00 1.18 1.24 1.30 1.36 1.43 1.51 1.60 1.70 1.81 1.94 2.09 2.27 2.47 2.72 3.02 3.40 Table 4: Ambient Light Sensor Gain Adjustment. Backlight LED Current Settings for Different Brightness Readings The main recipient of the light emitted by all visible spectrum LEDs is the human eye. It responds to light luminance in a non-linear, logarithmic way. The sensitivity of the human eye decreases rapidly as the luminance of the source increases. The LED current needs to change logarithmically in relation to the light brightness in order for the light brightness to be perceived linearly by the human eye. The AAT2893 has sixteen default LED current setting levels programmed in ALSn (from 09h to 18h) registers. These sixteen current level settings follow the logarithmic trend shown in Figure 24. A linear ambient light sensor output and a linear output brightness are set by using the default setting of SNSR=0 and ALSOUT=0 of the ALS_CFG2 (07h) register. For each light brightness sampling, one of the current levels corresponding to the ambient light reading will be selected to control the backlight LED current. If the desired current settings are different than the default, the user can change them by writing to ALSn (09h through 18h) registers. LED Current (mA) 100 10 1 0.1 0.1 1 10 100 1000 10000 100000 Brightness (Lux) Figure 24: Backlight LED Current vs Light Brightness. 40 Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com 202075B • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • September 4, 2012 DATA SHEET AAT2893 CABC Compatible, Ambient Light Control Boost LED Backlight Driver and Four LDOs AAT2893 allows automatic and manual modes for measurement of the ambient light sensor brightness. The automatic gain mode is selected by default value GM_ SEL = 0 in ALS_CFG0 (05h) register. For better accuracy during automatic mode, the AAT2893 will choose low gain resistor when the ambient light is bright and high gain resistor when the ambient light is dim. For the manual gain mode, all light brightness measurements are completed with the low gain resistor as set by GM_ SEL = 1 of the ALS_CFG0 (05h) register. Ambient Light Sensor Brightness Polling Time The AAT2893 offers two bits for programming the ambient light sensor brightness polling time. There are four different polling times: 0.5s, 1s, 1.5s and 2s selected by writing PTIME<1:0> bits of the ALS_CFG2 (07h) register. If an automatic ambient light sensor polling mode is selected by default PMODE = 0 of ALS_CFG0 (05h) register, the AAT2893 will periodically update the information about the surrounding brightness at an interval of every elapsed time. Refer to Figure 22 for A/D conversion timing diagram. Manual ambient sensor polling mode can also be selected by writing PMODE = 1 to ALS_CFG0 (05h) register. Mode GC1 GC2 Current µA/100Lux H-Gain Mode L-Gain Mode 1 0 0 1 60 6.31 Table 6: Rohm BH1600FVC Ambient Light Sensor Output Current Level. Parameter Value Maximum Brightness (Lux) Floor Brightness (Lux) ALS Output (μA/10 Lux) Gain Resistor (KΩ) Gain Adjustment (%) AMB-IN Full-Scale (V) Maximum. LED Current (mA) Floor Current (mA) Brightness / Floor Log (Brightness / Floor) Log current per level Brightness / Level k factor 10000 64 0.63 4 -18.75 1.92 28.60 0.9 156.25 2.19 0.10 662.4 0.68 Table 7: Determination of LED Current vs Brightness in a Logarithmic Relationship. Eq.1: log 15 AAT2893 Programming Examples Example 1: Ambient Light Sensor Linear Brightness Readings and Logarithmic Backlight Response SNSR = 0: Linear Measurement ALSOUT = 0: Linear Output Backlight Current: Logarithmic Response Brightness (Lux) LED Current (mA) 1--64 64--10000 0.9 0.9 to 28.6 in log scale Table 5: Sensor Requirements for Example 1. Ambient light sensor model BH1600FVC from Rohm is used for all examples: (Brightness Floor ( Ambient Light Sensor Brightness Gain Mode = 0.15 Setup Description: Ambient light sensor model BH1600FVC from Rohm is used with the AAT2893 demo board (Figures 30 and 31). The demo board jumper P3 controls the gain setting GC2 and jumper P4 controls the gain setting GC1. Pin 1 (logic 1) on the jumpers P3 and P4 is designated by the square pad in Figure 28. • Select low gain ALS output (GC1 = 0, GC2 = 1) • Backlight LED Current=28.6mA is selected, or doesn't need to be set • Resistor set of 4KΩ, 16KΩ is calculated for the application • Enable Backlight channel. (BL_EN = 1) • Ambient light sensor has no DC offset • Ambient light sensor gain adjustment is -18.75% • Linear ALSOUT and SNSR are selected • SBIAS = 3.0V is selected • Enable Ambient Light Sensor. (ALS_EN = 1) • Light brightness is measured at 1s time intervals • Read register AMLRB (08h). Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com 202075B • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • September 4, 2012 41 DATA SHEET AAT2893 CABC Compatible, Ambient Light Control Boost LED Backlight Driver and Four LDOs • Default settings are used for ALS_BLn (09h to 18h) registers. The following commands need to be communicated to the AAT2893 through the I2C interface: • Write AAT2893 7-bit I2C address: 0x60 (first byte writes as C0h; binary 11000000) • Write to register BL_ENBLS (01h) data 02h ALS_BLn (09h 18h) Light Brightness (Lux) Log of Current/ Floor of Each Level LED Curent (mA) 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 64 726 1389 2051 2714 3376 4038 4701 5363 6026 6688 7350 8013 8675 9338 10000 0.00 0.10 0.20 0.30 0.40 0.50 0.60 0.70 0.80 0.90 1.00 1.10 1.20 1.30 1.40 1.50 0.9 1.1 1.4 1.8 2.3 2.9 3.6 4.5 5.7 7.2 9.0 11.4 14.3 18.0 22.7 28.6 • • • • Write to register ALS_CFG0 (05h) data 31h Write to register ALS_CFG1 (06h) data 01h Write to register ALS_CFG2 (07h) data 1Dh Read register AMLRB (08h); bits AMB[7:0] indicate the ambient light brightness level; first byte writes as C1h; all readings are listed in Table 8. AMB[7] is the sign (+ or -) bit. Register Data AMB_IN Voltage (mV) Register Address (Hex) (Dec) (Hex) (Binary) 13.10 148.73 284.36 419.98 555.61 691.24 826.86 962.49 1098.12 1233.74 1369.37 1504.99 1640.62 1776.25 1911.87 2047.50 09h 0Ah 0Bh 0Ch 0Dh 0Eh 0Fh 10h 11h 12h 13h 14h 15h 16h 17h 18h 4 5 6 8 10 13 16 20 25 32 40 51 64 80 101 127 4h 5h 6h 8h Ah Dh 10h 14h 19h 20h 28h 33h 40h 50h 65h 7Fh 0000100 0000101 0000110 0001000 0001010 0001101 0010000 0010100 0011001 0100000 0101000 0110011 1000000 1010000 1100101 1111111 Table 8: Ambient Light Sensor Linear Brightness Readings and Logarithmic Backlight Response. Example 2: Ambient Light Sensor Linear Brightness Readings and Linear Backlight Response SNSR = 0: Linear Measurement ALSOUT = 0: Linear Output Backlight Current: Linear Response Brightness (Lux) LED Current (mA) 1--40 40--10000 5 5 to 20 Table 9: Sensor Requirements for Example 2. 42 Parameter Value Maximum Brightness (Lux) Floor Brightness (Lux) ALS Output (μA/10Lux) Gain Resistor (kΩ) Gain Adjustment (%) AMB-IN Full-Scale (V) Maximum. LED Current (mA) Floor Current (mA) Brightness / Level (Lux) LED Current per Level 10000 40 0.63 4 -18.75 1.92 20 5 664 1 Table 10: Determination of LED Current vs Brightness in a Logarithmic Relationship. Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com 202075B • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • September 4, 2012 DATA SHEET AAT2893 CABC Compatible, Ambient Light Control Boost LED Backlight Driver and Four LDOs GC2 GC1 Mode 0 0 1 0 1 0 1 1 Shutdown H-Gain Mode L-Gain Mode Test Mode (input prohibition) Table 11: Rohm BH1600FVC Ambient Light Sensor Mode Settings. Setup Description: Ambient light sensor model BH1600FVC from Rohm is used with the AAT2893 demo board (Figures 30 and 31). The demo board jumper P3 controls the gain setting GC2 and jumper P4 controls the gain setting GC1. • Select low gain ALS output (GC1 = 0, GC2 = 1) (see Table 11) • Resistor set of 4kΩ, 16kΩ is calculated for the application • Enable backlight channel (BL_EN = 1) • Ambient light sensor has no DC offset • Ambient light sensor gain adjustment is -18.75% • Linear ALSOUT and SNSR are selected • SBIAS = 3.0V is selected • Enable Ambient Light Sensor. (ALS_EN = 1) • Light brightness is measured at an interval of 1s • Read register AMLRB (08h) • Write the data to ALS_BLn (09h to 18h) registers The following commands need to be communicated to AAT2893 through I2C: • Write AAT2893 7-bit I2C address: 0x60 (binary 11000000, first byte writes as C0h) • Write to register BL_ENBLS (01h) data 02h • Write to register ALS_CFG0 (05h) data 31h • Write to register ALS_CGF1 (06h) data 01h • Write to register ALS_CFG2 (07h) data 1Dh • Read register AMLRB (08h); bits AMB[7:0] indicate the ambient light brightness level; first byte writes as C1h; all readings are listed in Table 12 • Write to register ALS_BL0 (09h) data 16h • Write to register ALS_BL1 (0Ah) data 1Bh • Write to register ALS_BL2 (0Bh) data 1Fh • Write to register ALS_BL3 (0Ch) data 24h • Write to register ALS_BL4 (0Dh) data 28h • Write to register ALS_BL5 (0Eh) data 2Ch • Write to register ALS_BL6 (0Fh) data 31h • Write to register ALS_BL7 (10h) data 35h • Write to register ALS_BL8 (11h) data 3Ah • Write to register ALS_BL9 (12h) data 3Eh • Write to register ALS_BLA (13h) data 43h • Write to register ALS_BLB (14h) data 47h • Write to register ALS_BLC (15h) data 4Ch • Write to register ALS_BLD (16h) data 50h • Write to register ALS_BLE (17h) data 54h • Write to register ALS_BLF (18h) data 59h ALS_BLn (09h - 18h) Light Brightness (Lux) LED Curent (mA) AMB_IN Voltage (mV) Register Address (Hex) Register Data (Dec) (Hex) (Binary) 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 40 704 1368 2032 2696 3360 4024 4688 5352 6016 6680 7344 8008 8672 9336 10000 5.0 6.0 7.0 8.0 9.0 10.0 11.0 12.0 13.0 14.0 15.0 16.0 17.0 18.0 19.0 20.0 8.19 144.14 280.10 416.05 552.01 687.96 823.91 959.87 1095.82 1231.78 1367.73 1503.68 1639.64 1775.59 1911.55 2047.50 09h 0Ah 0Bh 0Ch 0Dh 0Eh 0Fh 10h 11h 12h 13h 14h 15h 16h 17h 18h 22 27 31 36 40 44 49 53 58 62 67 71 76 80 84 89 16h 1Bh 1Fh 24h 28h 2Ch 31h 35h 3Ah 3Eh 43h 47h 4Ch 50h 54h 59h 0010110 0011011 0011111 0100100 0101000 0101100 0110001 0110101 0111010 0111110 1000011 1000111 1001100 1010000 1010100 1011001 Table 12: Ambient Light Sensor Linear Brightness Readings and Linear Backlight Response. Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com 202075B • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • September 4, 2012 43 DATA SHEET AAT2893 CABC Compatible, Ambient Light Control Boost LED Backlight Driver and Four LDOs Example 3: Ambient Light Sensor Logarithmic Brightness and Logarithmic Backlight Response SNSR = 0: Linear Measurement ALSOUT = 1: Logarithmic Output Backlight Current: Logarithmic Response Brightness (Lux) LED Current (mA) 1--10 10--100 100--1000 1000--10000 5 10 15 20 Table 13: Sensor Requirements for Example 3. Parameter Value Maximum Brightness (Lux) Floor Brightness (Lux) ALS Output (μA/10Lux) Gain Resistor (kΩ) Gain Adjustment (%) AMB-IN Full-Scale (V) Maximum. LED Current (mA) Floor Current (mA) Brightness/Floor Log(Brightness/Floor) Log current per level k factor 1000 40 6 4 -18.75 1.92 20 5 25 1.40 0.04 0.43 Table 14: Determination of LED Current vs Brightness in a Logarithmic Relationship. log (Brightness Floor 15 ( Eq 2: = 0.09 Setup Description: Ambient light sensor model BH1600FVC from Rohm is used with the AAT2893 demo board (Figures 30 and 31). The demo board jumper P3 controls the gain setting GC2 and jumper P4 controls the gain setting GC1. 44 • Select high gain ALS output (GC1 = 1, GC2 = 0) (see Table 11). • Resistor set of 4kΩ, 16kΩ is calculated for the application • Enable backlight channel (BL_EN = 1) • Ambient light sensor has no DC offset • Ambient light sensor gain adjustment is -18.75% • Logarithmic ALSOUT and Linear SNSR are selected • SBIAS = 3.0V is selected • Light brightness is measured at an interval of 1s time • Read register AMLRB (08h) • Write to registers ALS_BLn (09h to 18h) the data The following commands need to be communicated to AAT2893 through I2C: • Write AAT2893 7-bit I2C address: 0x60 (binary 11000000; first byte writes as C0h) • Write to register BL_ENBLS (01h) data 02h • Write to register ALS_CFG0 (05h) data 31h • Write to register ALS_CFG1 (06h) data 01h • Write to register ALS_CFG2 (07h) data 5Dh • Read register AMLRB (08h); bits AMB[7:0] indicate the ambient light brightness level; first byte writes C1h; all readings are listed in Table 15. • Write to register ALS_BL0 (09h) data 16h • Write to register ALS_BL1 (0Ah) data 1Bh • Write to register ALS_BL2 (0Bh) data 1Fh • Write to register ALS_BL3 (0Ch) data 24h • Write to register ALS_BL4 (0Dh) data 28h • Write to register ALS_BL5 (0Eh) data 2Ch • Write to register ALS_BL6 (0Fh) data 31h • Write to register ALS_BL7 (10h) data 35h • Write to register ALS_BL8 (11h) data 3Ah • Write to register ALS_BL9 (12h) data 3Eh • Write to register ALS_BLA (13h) data 43h • Write to register ALS_BLB (14h) data 47h • Write to register ALS_BLC (15h) data 4Ch • Write to register ALS_BLD (16h) data 50h • Write to register ALS_BLE (17h) data 54h • Write to register ALS_BLF (18h) data 59h Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com 202075B • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • September 4, 2012 DATA SHEET AAT2893 CABC Compatible, Ambient Light Control Boost LED Backlight Driver and Four LDOs ALS_BLn (09h 18h) Light Brightness (Lux) Log of Brightness / Floor Level LED Curent (mA) 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 40 50 61 76 94 117 145 180 223 276 342 424 525 651 807 1000 0 0.09 0.19 0.28 0.37 0.47 0.56 0.65 0.75 0.84 0.93 1.03 1.12 1.21 1.30 1.40 5.0 6.0 7.0 8.0 9.0 10.0 11.0 12.0 13.0 14.0 15.0 16.0 17.0 18.0 19.0 20.0 Register Data AMB_IN Voltage (mV) Register Address (Hex) (Dec) (Hex) (Binary) 78.00 96.67 119.81 148.49 184.03 228.07 282.66 350.32 434.17 538.09 666.89 826.51 1024.35 1269.53 1573.40 1950.00 09h 0Ah 0Bh 0Ch 0Dh 0Eh 0Fh 10h 11h 12h 13h 14h 15h 16h 17h 18h 22 27 31 36 40 44 49 53 58 62 67 71 76 80 84 89 16h 1Bh 1Fh 24h 28h 2Ch 31h 35h 3Ah 3Eh 43h 47h 4Ch 50h 54h 59h 0010110 0011011 0011111 0100100 0101000 0101100 0110001 0110101 0111010 0111110 1000011 1000111 1001100 1010000 1010100 1011001 Table 15: Ambient Light Sensor Logarithmic Brightness Readings and Logarithmic Backlight Response. Content Adaptive Brightness Control (CABC) The CABC response to an external PWM signal is set by the filter capacitor, CFLTR, connected to the FLTR pin. In order to select CFLTR properly, three conditions need to be known: 1. PWM signal frequency at the PWM pin 2. The desired rate of change of the backlight current from one level to another 3. The minimum PWM duty cycle. The capacitor (CFLTR) connected to the FLTR pin has an internal resistor RF = 73.3kΩ in parallel with ground. The filter capacitor CFLTR pin is charged with a 20μA current source that is modulated with the PWM duty cycle. Refer to Figures 25 and 26 for circuit and timing diagrams. The value for CFLTR can be calculated with the following equation: tF 3 ∙ RF ∙ ln (D0 D1 ( CFLTR = Where, and D0 is the PWM Duty Cycle before the adjustment D1 is the PWM Duty Cycle after the adjustment. If the selected CFLTR capacitor value is smaller than 5nF, then the ripple appearing on the backlight PWM current will increase. For external PWM signals equal or lower than 10% duty cycle, the bottom level of the ripple can cause the internal comparators to trip and as a result, the part will switch to a maximum duty cycle of 97.8% for a few clock periods. If the selected CFLTR value is large, the ripple on the backlight PWM current will be reduced, but it may not be possible to achieve a fast change (tF) of the backlight current level or the desired duty cycle. Table 16 shows the recommended CFLTR Value for Different tF. If the CABC function is not desired it can be disabled by changing bit CABC from 0 to 1 in BL_ENBLS (01h) register. The AAT2893 will operate with a maximum duty cycle of 97.8% and the CFLTR capacitor is not necessary. CFLTR (nF) tF (ms) 6.8 10 22 33 47 68 100 220 1.5 2.8 3.6 5.1 6.9 10.2 18 40 Table 16: Recommended CFLTR Value for Different tF. Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com 202075B • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • September 4, 2012 45 DATA SHEET AAT2893 CABC Compatible, Ambient Light Control Boost LED Backlight Driver and Four LDOs VIN External PWM Control Input 20μA PWM ILED I2C & ALS Control VFLTR RF 73.3kΩ FLTR CF Figure 25: CABC Circuit Diagram. tF ILED 0 Time Figure 26: CABC Timing. Note: A small value CFLTR will result in faster transition time (tF) between current levels but is limited to 5nF by the backlight PWM current ripple. 46 Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com 202075B • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • September 4, 2012 DATA SHEET AAT2893 CABC Compatible, Ambient Light Control Boost LED Backlight Driver and Four LDOs LED Selection PWM Duty Cycle vs WLED Current (11 WLEDs) 30 25 ILED (mA) The AAT2893 is specifically designed for driving white LEDs in TFT-LCD backlighting applications but the device design allows the AAT2893 to drive most types of LEDs with forward voltage specifications ranging from 2.0V to 4.7V. LED applications may include mixed arrangements for display backlighting, color (RGB) LEDs, infrared (IR) diodes or any other load needing a constant current source generated from a varying input voltage. ILED vs Efficiency (11 WLEDs) 85 80 Efficiency (%) 75 VIN = 3.6V VIN = 4.2V VIN = 5.0V VIN = 5.5V 0 10 20 30 40 50 60 70 80 90 100 PWM Duty (%) Figure 28: PWM Duty Cycle vs WLED Current at 11 WLEDs Application. Input Voltage vs Max WLED Current (AAT2893 - 1) 30 29 28 27 26 11 WLEDs 25 24 23 22 21 70 20 65 3 60 VIN = 3.0V 55 VIN = 3.6V 3.5 3.75 4 4.25 4.5 4.75 5 5.25 5.5 Input Voltage (V) VIN = 5.0V 45 3.25 Figure 29: Input Voltage vs Max WLED Current at 11 WLEDs Application. VIN = 4.2V 50 40 VIN = 3.0V 10 0 Max. ILED (mA) The maximum number of WLED depends on the OVP of the AAT2893 part and the forward voltage (VF) of WLED. The OVP of AAT2893-1 is 42V, to a general WLED with about 3.3V forward voltage, it means AAT2893 has ability to drive more than 10 LEDs in series. Figure 27, 28 and 29 show the efficiency, PWM duty vs WLED current and WLED current at different input voltage when AAT2893 drive 11 WLEDs. 15 5 The low-dropout current sinks in the AAT2893 maximize performance and make it capable of driving LEDs with high forward voltage. Driving 11 WLEDs Application 20 VIN = 5.5V 0 5 10 15 20 25 30 ILED (mA) Figure 27: WLED Current vs Efficiency at 11 WLEDs Application. Inductor Selection Inductor value, saturation current and DCR are the most important parameters in selecting an inductor for the AAT2893. The suitable inductance range for the AAT2893 is 4.7μH to 22μH. Higher inductance lowers the step-up converter's RMS current value. Together with lower DCR value of the inductor, it makes the total inductor power loss become much lower. Considering inductor size and cost, 4.7μH inductance is most suitable. Considering the inductor copper loss, the inductor DCR value together with the RMS current flowing through the Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com 202075B • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • September 4, 2012 47 DATA SHEET AAT2893 CABC Compatible, Ambient Light Control Boost LED Backlight Driver and Four LDOs inductor leads to inductor conduction loss and also affects total efficiency. Larger DCR leads to larger conduction loss and reduces total efficiency. The inductor conduction loss can be estimated using the following equation: (I2L_MAX + I2L_MIN + IL_MAX ∙ IL_MIN) ∙ DCR PL_LOSS = I2L_RMS ∙ DCR = 3 Where IL_MAX and IL_MIN are the inductor peak current and minimum current respectively. Inductor saturation current is also a key parameter in selecting an inductor. For the step-up converter, the peak inductor current is the DC input current plus half the inductor peak-to-peak current ripple. DC input current: VOUT ∙ ILED IIN = IL_PP VIN ∙ (VOUT - VIN) 2 = VOUT ∙ L ∙ f VOUT ∙ ILED VIN ∙ η + VIN ∙ (VOUT - VIN) 2 ∙ VOUT ∙ L ∙ f For example, for a white LED with 3.2V VF, 20mA current, 81% efficiency and VIN less than 3.6V, the inductor peak current is: IL_PEAK = 3.2 ∙ 8 ∙ 0.02 3.6 ∙ (3.2 ∙ 8 - 3.6) = 330mA + 3.6 ∙ 0.81 2 ∙ 3.2 ∙ 8 ∙ 10μ ∙ 1M Compensation Component Selection A compensation capacitor CCOM is used for step-up converter loop compensation and soft startup time control. Loop compensation requires matching values for CCOM, COUT, ILED, and VOUT: COUT CCOM 48 < ILED (nF) = (1 ∙ 30 ∙ 40) 30(nF) = 40(nF) A higher value for CCOM lengthens the soft startup time. So to balance the startup time and the loop stability, 56nF is selected. The relationship between CCOM and startup time is almost linear, with startup time x 105 magnification of CCOM; thus 56nF CCOM leads to a soft startup time of 5.6ms. Values of 56nF for CCOM and 1μF for COUT are suitable in most cases. To achieve maximum efficiency, a low VF Schottky diode is recommended. For an AAT2893 driving 10 white LEDs with up to 4V forward voltage, the diode voltage rating should be higher than 40V. Selecting a diode with DC rated current being equal to the input current allows an adequate margin for safe use. Inductor peak current: IL_PEAK = IIN + CCOM > (COUT ∙30 ∙ VOUT) Schottky Diode Selection VIN ∙ η Inductor peak-to-peak current ripple: IL_PP = For example, considering the worse case of AAT2893 driving 10 white LEDs with forward voltages 4V, a COUT value of 1μF, and LED maximum current of about 30mA, the value of CCOM should be higher than 40nF. ILED 30 ∙ 10-6 ∙ VOUT Printed Circuit Board Layout Recommendations Boost converter performance can be adversely affected by poor layout. Possible impact includes high input and output voltage ripple, poor EMI performance, and reduced operating efficiency. Every attempt should be made to optimize the layout in order to minimize parasitic effects on PCB (stray resistance, capacitance, and inductance) and EMI coupling at the high frequency switching node. A suggested PCB layout for the AAT2893 is shown in Figures 31. The following PCB layout guidelines should be considered: 1.Place the input and output decoupling capacitors C1, C3, C5, C2, C4, C8, C9 as close to the chip as possible to reduce switching noise and output ripple. 2.Keep the power traces (GND, LX VOUT and VIN) short, direct, and wide to allow large current flow. Place sufficient multiple-layer pads, when needed, to change the trace layer. 3.Maintain a ground plane and connect to the IC PGND pin(s) as well as the PGND connections of CIN and COUT. Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com 202075B • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • September 4, 2012 DATA SHEET AAT2893 CABC Compatible, Ambient Light Control Boost LED Backlight Driver and Four LDOs Schematic and Layout 1 3 5 7 9 ILED D1 E3 E2 COMP LDOD C2 4.7µF B1 A4 2 4 6 8 10 AMB_ IN Gnd SDA TP9 SBIAS TP4 A2 C8 2.2µF A1 C9 2.2µF GND LDOC TP5 LDOD SBIAS GC2 R13 0Ω 1 R10 (open) 2 Header 5X 2 C10 2.2µF C4 2.2µF A3 DGND LDOC TP3 LDOB TP6 P5 SCL LDOB FLTR B4 PWM R2 0Ω LDOA C3 2.2µF LDOA U1 AAT2893 PWM TP2 VIN C2 E4 C6 56nF EN D6 JP3 IN _LDO SDA • D4 JP2 D3 VIN C7 10nF D7 SDA P2 D2 • • D8 SCL R11 100kΩ PWM D9 C3 EN D10 JP1 SCL R9 100kΩ PWM D11 IN AMB_IN B3 TP10 OUT E1 LX B2 VIN D5 • • SDM20U40 SBIAS P1 D4 C1 • C1 4.7µF VIN D3 • DS1 C4 TP1 D2 PGND L1 4.7µH D1 AGND C5 2. 2µF R12 0Ω 3 U2 OUT GC2 GND GC1 VCC NC P3 GC2 6 5 4 BH1600FVC SBIAS GC1 P4 GC1 GND Figure 30: AAT2893 WLCSP-20 Evaluation Board Schematic. Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com 202075B • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • September 4, 2012 49 DATA SHEET AAT2893 CABC Compatible, Ambient Light Control Boost LED Backlight Driver and Four LDOs Figure 31: AAT2893 Evaluation Board Top and Bottom Side Layout. Figure 32: AAT2893 Evaluation Board WLCSP-20 package Top and Bottom Side Layout. 50 Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com 202075B • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • September 4, 2012 DATA SHEET AAT2893 CABC Compatible, Ambient Light Control Boost LED Backlight Driver and Four LDOs Component Part Number U1 AAT2893IUL U2 C1,C2 C3, C4, C8, C9, C10 C5 C6 C7 D1-D10 D11 DS1 L1 P5 R2,R13, R12 R9, R11 R10 BH1600FVC GRM188R60J475K GCM188R70J225KE22 GRM21BR61H225KA73L GRM188R71C563K GRM188R71H103KA01 RS-0805UW SDM20U40 CDRH3D14-4R7NC Chip Resistor Description Ambient Light Control Boost LED Backlight Driver IC with 4 LDOs; WLCSP20 Ambient Light Sensor IC; WSOF6 Cap Ceramic 4.7μF 0603 X5R 6.3V 10% Manufacturer Skyworks Rohm 2.2μF, 6.3V, X7R, 0603 2.2μF, 50V, X7R, 0805 Cap Ceramic 0.056μF 0603 X7R 16V 10% 10nF, 50V, X7R, 0603 30mA White LED 0805 Not populated. Do not solder Surface Mount Schottky Barrier Diode Power Inductor 4.7μH 1.1A SMD 0.1" Header, 2x5 pins 0Ω, 1%, 1/8W; 0402 100kΩ, 1%, 1/4W; 0603 Open, reserved for external Gain Resistor adjust Murata Realstar Diodes Sumida Vishay Table 16: AAT2893 Evaluation Board Bill of Materials (BOM). Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com 202075B • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • September 4, 2012 51 DATA SHEET AAT2893 CABC Compatible, Ambient Light Control Boost LED Backlight Driver and Four LDOs Ordering Information Package Marking1 OVP Part Number (Tape and Reel)2 WLCSP-20 WLCSP-20 V9YW W5YW 42V 33V AAT2893IUL-1-T1 AAT2893IUL-2-T1 Skyworks Green™ products are compliant with all applicable legislation and are halogen-free. For additional information, refer to Skyworks Definition of Green™, document number SQ04-0074. Package Information WLCSP-20 D1 0.650 0.200 0.380 0.070 2.625 2.095 1.600 BSC 1.200 BSC N/A 0.200 BSC 0.400 BSC 0.265 0.200 0.200 20 Balls 0.735 0.225 0.405 0.105 2.660 2.130 + + + + 4 + + + + + 3 + + + + + 2 + + + + + 1 E D C D B A (Bottom View) 0.290 - A3 A (Side View) Y1 NxØb X1 0.240 0.600 0.600 - + A2 X X LINE_1 Y W LINE_2 1/2 E 0.565 0.175 0.355 0.035 2.590 2.060 A1 X A A1 A2 A3 D E D1 E1 SD SE e b X Y X1 Y1 N e E Max e Nominal E1 Min SE Symbol Y All dimensions in millimeters. (Side View) LDOD 1/2 D XX: V9 - 42V XX: W5 - 33V Ø 0.2 (Ref.) PIN A1 Indication (Top View) 1. YW = Year and week code. 2. Sample stock is generally held on part numbers listed in BOLD. 52 Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com 202075B • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • September 4, 2012 DATA SHEET AAT2893 CABC Compatible, Ambient Light Control Boost LED Backlight Driver and Four LDOs Copyright © 2012 Skyworks Solutions, Inc. All Rights Reserved. Information in this document is provided in connection with Skyworks Solutions, Inc. (“Skyworks”) products or services. These materials, including the information contained herein, are provided by Skyworks as a service to its customers and may be used for informational purposes only by the customer. Skyworks assumes no responsibility for errors or omissions in these materials or the information contained herein. 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