DATA SHEET AAT2803 Six-Channel White LED Backlight Charge Pump with Flash General Description Features The AAT2803 is a dual charge pump designed to support both white LED backlight and flash applications for systems operating with lithium-ion/polymer batteries. The backlight charge pump is capable of driving up to six LEDs at a total of 180mA. The current sinks may be operated in group or in parallel for driving higher current LEDs. To maximize power efficiency, the charge pump operates in 1X, 1.5X, or 2X mode, where the mode of operation is automatically selected by comparing the forward voltage of each LED with the input voltage. Skyworks' AS2Cwire™ (Advanced Simple Serial Control™) serial digital input is used to enable, disable, and set current for each LED with a 16-level logarithmic scale plus four low-current settings down to 50μA for optimized efficiency, with a low housekeeping current of only 50μA. • VIN Range: 2.7V to 5.5V • Dual Charge Pump: ▪ Flash: Charge Pump Doubler ▪ Backlight: Tri-Mode Charge Pump • Backlight Charge Pump: ▪ Programmable Current With Single GPIO ▪ 16 Current Steps ▪ 15/20/30mA Max Current ▪ Four Low Current Settings ▪ Individual Main/Sub-Group Control ▪ Low IQ (50μA) for Low-Current Mode ▪ Drives Six Channels of LEDs • Flash Charge Pump: ▪ Regulated VOUT_FL 4.5/5.0 Volts ▪ Up to 300mA of Current for Flash • 1MHz Constant Switching Frequency • Independent Backlight/Flash Control • Built-In Thermal Protection • Built-In Auto-Disable for Open Circuit • Automatic Soft Start • IQ <1μA in Shutdown • Available in QFN44-24 Package The flash charge pump is a charge pump doubler with a regulated output voltage. It is designed to deliver 120mA of continuous current and up to 300mA of pulsed current. It has an independent enable pin for improved power savings. The AAT2803 is equipped with built-in protection, shortcircuit, and auto-disable for load short-circuit condition. Built-in soft-start circuitry prevents excessive inrush current during start-up. A low-current shutdown feature disconnects the load from VIN and reduces quiescent current to less than 1μA. Applications • • • • The AAT2803 is available in a Pb-free, space-saving, thermally enhanced 24-pin 4x4mm QFN package and is rated over the -40°C to +85°C temperature range. Color (RGB) Lighting Programmable Current Sink White LED Backlighting White Photo Flash for Digital Still Cameras Typical Application C1 1µF C1+ VIN V IN C2 1µF C1- C2+ C3 1µF C2- C3 + C3 VOUT Flash COUT 1µF CIN 1µF AAT2803 Backlight D6 EN_FL EN/SET ENFL EN/SET GND D5 D4 D3 D2 D1 COUT 1µF D6 D5 D4 D3 D2 D1 Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com 202064A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • June 14, 2012 1 DATA SHEET AAT2803 Six-Channel White LED Backlight Charge Pump with Flash Pin Descriptions Pin # Symbol Function 1 2 3 4, 14 C1C1+ VOUT_FL VIN 5 EN_FL 6, 7, 23 8 9 10 11 12 13, 15, 24 16 17 18 19 20 21 N/C VOUT_BL C2+ C3+ C3C2GND D1 D2 D3 D5 D4 D6 22 EN/SET Flying capacitor 1 negative terminal. Flying capacitor 1 positive terminal. Connect a 1μF capacitor between C1+ and C1-. Flash output voltage. Requires 1μF capacitor connected between this pin and ground. Input power supply. Requires 1μF capacitor connected between this pin and ground. Enable pin for flash charge pump. For normal operation, connect to VIN. When connected low, the flash charge pump shuts down and consumes less than 1μA of current. No connect. Backlight output voltage charge pump. Requires 1μF capacitor connected between this pin and ground. Flying capacitor 2 positive terminal. Connect a 1μF capacitor between C2+ and C2-. Flying capacitor 3 positive terminal. Connect a 1μF capacitor between C3+ and C3-. Flying capacitor 3 negative terminal. Flying capacitor 2 negative terminal. Ground. Current sink input #1. Current sink input #2. Current sink input #3. Current sink input #5. Current sink input #4. Current sink input #6. AS2Cwire serial interface control pin for backlight charge pump. It controls the current settings for all six channels. This pin should not be left floating. Exposed paddle (bottom); connect to GND directly beneath package. EP Pin Configuration QFN44-24 (Top View) D5 D4 D6 EN/SET N/C GND 19 20 21 22 23 24 C1C1+ VOUT_FL VIN EN_FL N/C 1 18 2 17 3 16 AAT2803 4 15 5 14 6 13 D3 D2 D1 GND VIN GND 12 11 9 10 8 7 C2C3C3+ C2+ VOUT_BL N/C 2 Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com 202064A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • June 14, 2012 DATA SHEET AAT2803 Six-Channel White LED Backlight Charge Pump with Flash Absolute Maximum Ratings1 Symbol VIN VEN/SET TJ TLEAD Description Input Voltage EN/SET to GND Voltage Operating Junction Temperature Range Maximum Soldering Temperature (at leads, 10 sec) Value Units -0.3 to 6 -0.3 to VIN + 0.3 -40 to 150 300 V V °C °C Value Units 2.0 50 W °C/W Thermal Information2 Symbol PD JA Description Maximum Power Dissipation Maximum Thermal Resistance 3 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. Only one Absolute Maximum Rating should be applied at any one time. 2. Mounted on an FR4 board. 3. Derate 6.25mW/°C above 25°C. Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com 202064A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • June 14, 2012 3 DATA SHEET AAT2803 Six-Channel White LED Backlight Charge Pump with Flash Electrical Characteristics1 VIN = 3.6V, CIN = COUT = C1 = C2 = C3 = 1.0μF; TA = -40°C to +85°C, unless otherwise noted. Typical values are TA = 25°C. Symbol VIN ICC ISHDN IDX I(D-Match) VTH VOUT IOUT TSS FCLK VEN(L) VEN(H) TEN/SET LO TEN/SET_HI_MIN TEN/SET_HI_MAX TOFF TLAT IEN/SET;EN_FL Description Conditions Operation Range Operating Current Shutdown Current ISINK Average Current Accuracy2 Current Matching Between Any Two Current Sink Inputs3, 4 1X to 1.5X or 1.5X to 2X Transition Threshold at Any DX Pin Output Voltage (Flash Charge Pump)5 Max Continuous Output Current (Flash Charge Pump)5 Max Pulsed Output Current5 Soft-Start Time Clock Frequency Enable Threshold Low Enable Threshold High EN/SET Low Time Minimum EN/SET High Time Maximum EN/SET High Time EN/SET Off Timeout EN/SET Latch Timeout Input Leakage Min Typ 2.7 1X Mode, 3.0 £ VIN £ 5.5, Active, No Load Current; EN/SET = VIN; EN_FL= GND 1.5X Mode, 3.0 £ VIN £ 5.5, Active, No Load Current; EN/SET = VIN; EN_FL= GND 2X Mode, 3.0 £ VIN £ 5.5, Active, No Load Current; EN/SET = VIN; EN_FL = GND VOUT_FLASH = 5V; EN/SET = GND; EN_FL = VIN 50μA Setting, 1X Mode; EN/SET = VIN; EN_FL = GND EN/SET = 0 ISET = 30mA, TA = 25°C ISET = 4.1mA, TA = 25°C Units 5.5 V 0.3 1 1.0 3.0 2.0 3.7 2.0 4.5 50 27 3.69 VF:D1:D4 = 3.6V 3.0< VIN < 5V, IOUT = 120mA; EN_FL = VIN 4.3 VIN = 3.3V; VOUT = 4.5V; EN_FL = VIN 120 VIN = 3.6V; VOUT = 4.5V; IPULSED = 250ms Backlight Charge Pump Flash Charge Pump VIN = 2.7V VIN = 5.5V Max 30 4.1 μA 1.0 33 4.51 μA mA 0.5 % 150 mV 4.5 4.7 V mA 300 100 200 1.0 μs 0.4 1.4 0.3 75 50 VEN/SET;EN_FL = 5V; VIN = 5V mA -1.0 75 500 500 1.0 MHz V V μs ns μs μs μs μA 1. The AAT2803 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. Determined by the average of all active channels. 3. Current matching is defined as the deviation of any sink current from the average of all active channels. 4. Specification applies only to the tri-mode charge pump. 5. Specification applies only to the charge pump doubler. 4 Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com 202064A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • June 14, 2012 DATA SHEET AAT2803 Six-Channel White LED Backlight Charge Pump with Flash Typical Characteristics–Flash Driver Charge Pump Section Maximum Current Pulse vs. Supply Voltage (VOUT_FL = 4.5V; EN_FL = VIN; EN/SET = GND) Output Voltage (V) 4.60 4.56 4.52 3.6V 4.48 3.0V 3.3V 4.44 2.7V 4.40 0.1 1.0 10.0 100.0 1000 Maximum Current Pulse (mA) Output Voltage vs. Output Current (VOUT_FL = 4.5V; EN_FL = VIN; EN/SET = GND) 450 400 One-shot pulse duration = 250ms VOUT > 4.0V 350 300 250 200 150 100 50 0 3.0 3.1 Output Current (mA) 3.2 3.3 3.4 3.5 3.6 3.7 3.8 3.9 4.0 4.1 4.2 Supply Voltage (V) Start-Up Time Start-Up Time (50mA Load) (100mA Load) EN_FLSH (1V/div) EN_FLSH (1V/div) VOUT_FL (1V/div) VOUT_FL (1V/div) 100µ µs/div 100µ µs/div Load Response vs. Time Load Response vs. Time (50mA Load) (100mA Load) VIN = 3.5V VIN = 3.5V VOUT_FL (10mV/div) VOUT_FL (10mV/div) IOUT (20mA/div) IOUT (50mA/div) 5ms/div 5ms/div Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com 202064A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • June 14, 2012 5 DATA SHEET AAT2803 Six-Channel White LED Backlight Charge Pump with Flash Typical Characteristics–Flash Driver Charge Pump Section Output Ripple Voltage vs. Time Output Ripple Voltage vs. Time (IOUT = 50mA @ VIN = 3.5V) (IOUT = 100mA @ VIN = 3.5V) VIN (10mV/div) VIN (10mV/div) VOUT (10mV/div) VOUT (20mV/div) IIN (10mA/div) IIN (10mA/div) 500ns/div 500ns/div Supply Current vs. Supply Voltage Oscillator Frequency vs. Supply Voltage 2.75 2.50 Oscillator Frequency (MHz) Supply Current (mA) 3.00 IOUT = 0µA C3 = 1µF VEN_FL = VIN 2.25 2.00 1.75 1.50 1.25 1.00 2.5 3.0 3.5 4.0 Supply Voltage (V) 6 4.5 5.0 1.30 1.25 +25°C 1.20 1.15 +85°C -40°C 1.10 2.7 3.2 3.7 4.2 Supply Voltage (V) Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com 202064A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • June 14, 2012 4.7 DATA SHEET AAT2803 Six-Channel White LED Backlight Charge Pump with Flash Typical Characteristics–White LED Backlight Driver Section Unless otherwise noted, VIN = 3.6V, CIN = COUT = C1 = C2 = C3 = 1.0μF; TA = 25°C. Turn-On to 1X Mode Efficiency vs. Supply Voltage 100 4.1mA VF = 2.9V 10.2mA VF = 3.1V (VIN = 4.2V; 20mA Load) 20mA VF = 3.4V EN (2V/div) Efficiency (%) 90 CP (2V/div) VSINK (500mV/div) 80 70 IIN (200mA/div) 60 50 2.8 3.0 3.2 3.4 3.6 3.8 4.0 4.2 100µ µs/div Supply Voltage (V) Turn-On to 1.5X Mode Turn-On to 2X Mode (VIN = 3.8V; 20mA Load) (VIN = 2.8V; 20mA Load) EN (2V/div) EN (2V/div) CP (2V/div) VSINK (500mV/div) CP (2V/div) VSINK (500mV/div) IIN (200mA/div) IIN (200mA/div) 100µ µs/div 100µ µs/div Turn-Off from 1.5X Mode Current Matching vs. Temperature (VIN = 3.5V; 20mA Load) 20.2 Channel 1 Channel 2 EN (2V/div) Current (mA) 20.0 VF (1V/div) IIN (100mA/div) 19.8 Channel 5 19.6 Channel 3 19.4 Channel 4 Channel 6 19.2 -40 100µ µs/div -20 0 20 40 60 80 Temperature (°°C) Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com 202064A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • June 14, 2012 7 DATA SHEET AAT2803 Six-Channel White LED Backlight Charge Pump with Flash Typical Characteristics–White LED Backlight Driver Section Unless otherwise noted, VIN = 3.6V, CIN = COUT = C1 = C2 = C3 = 1.0μF; TA = 25°C. Load Characteristics Load Characteristics (VIN = 3.8V; 1.5X Mode; 15mA Load) (VIN = 2.9V; 2X Mode; 15mA Load) VIN (40mV/div) VIN (40mV/div) CP (40mV/div) CP (40mV/div) VSINK (40mV/div) VSINK (40mV/div) 500ns/div 500ns/div Load Characteristics Load Characteristics (VIN = 4.0V; 1.5X Mode; 20mA Load) (VIN = 3.1V; 2X Mode; 20mA Load) VIN (40mV/div) VIN (40mV/div) CP (40mV/div) CP (40mV/div) VSINK (40mV/div) VSINK (40mV/div) 500ns/div 500ns/div Load Characteristics Load Characteristics (VIN = 4.3V; 1.5X Mode; 30mA Load) (VIN = 3.6V; 2X Mode; 30mA Load) VIN (40mV/div) VIN (40mV/div) CP (40mV/div) CP (40mV/div) VSINK (40mV/div) VSINK (40mV/div) 500ns/div 8 500ns/div Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com 202064A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • June 14, 2012 DATA SHEET AAT2803 Six-Channel White LED Backlight Charge Pump with Flash Typical Characteristics–White LED Backlight Driver Section Unless otherwise noted, VIN = 3.6V, CIN = COUT = C1 = C2 = C3 = 1.0μF; TA = 25°C. TLAT vs. VIN TOFF vs. VIN 350 400 350 300 -40°C -40°C 300 TOFF (µ µs) TLAT (µ µs) 250 200 150 25°C 85°C 100 250 200 25°C 150 85°C 100 50 50 0 0 2.7 2.9 3.1 3.3 3.5 3.7 3.9 4.1 4.3 4.5 4.7 4.9 5.1 5.3 5.5 2.7 2.9 3.1 3.3 3.5 3.7 3.9 4.1 4.3 4.5 4.7 4.9 5.1 5.3 5.5 VIN (V) VIN (V) Input Ripple vs. VIN VIH vs. VIN 1.2 25 1 -40°C 0.9 15 10 VIH (V) Amplitude (mV) 1.1 30mA 20 20mA 0.7 25°C 0.6 85°C 0.5 10.2mA 5 0.8 0.4 0.3 0.2 0 2.50 2.67 2.84 3.01 3.18 3.35 3.52 3.69 3.86 4.03 4.2 VIN (V) 2.7 2.9 3.1 3.3 3.5 3.7 3.9 4.1 4.3 4.5 4.7 4.9 5.1 5.3 5.5 VIN (V) VIL vs. VIN 1.2 1.1 1 VIL (V) 0.9 -40°C 0.8 0.7 0.6 0.5 25°C 85°C 0.4 0.3 0.2 2.7 2.9 3.1 3.3 3.5 3.7 3.9 4.1 4.3 4.5 4.7 4.9 5.1 5.3 5.5 VIN (V) Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com 202064A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • June 14, 2012 9 DATA SHEET AAT2803 Six-Channel White LED Backlight Charge Pump with Flash Functional Block Diagram C1+ C1- Soft-Start 2X Charge Pump EN_FL 1MHz Oscillator VOUT_FL VIN VREF Soft-Start Control 1MHz Oscillator C2 + 1X 1.5X 2X Charge Pump C2 C3 + C3 - Voltage Reference 6 x 16 bit ROM EN/SET AS 2Cwire Interface 6 x 16 bit ROM VOUT_BL D/A D1 D/A D2 D/A D3 D/A D4 D/A D5 D/A D6 GND Functional Description The AAT2803 is a dual charge pump targeted for backlight and flash applications. The charge pump for white LED applications is a tri-mode load switch (1X) and high efficiency (1.5X or 2X) charge pump device. To maximize power conversion efficiency, an internal sensing circuit monitors the voltage required on each constant current sink input and sets the load switch and charge pump modes based on the input battery voltage and the current sink input voltage. As the battery discharges over time, the backlight charge pump is enabled when any of the six current sink inputs near dropout. The charge pump initially starts in 1.5X mode. If the charge pump output drops enough for any current source output to become close to dropout, the charge pump will automatically transition to 2X mode. For flash applications, charge pump doubler architecture is used to support the high current demand required by the application. Charge pump regulation is achieved by sensing the output voltage through an internal resistor 10 divider network. A switch doubling circuit is enabled when the divided output drops below a preset trip point controlled by an internal comparator. The free-running charge pump switching frequency is approximately 1MHz. The charge pump is designed to deliver 120mA of continuous current and 300mA of pulsed current. The AAT2803 requires only six external components: three 1μF ceramic capacitors for the charge pump flying capacitors (C1, C2, and C3), one 1μF ceramic input capacitor (CIN), one 0.33μF to 1μF ceramic capacitor for the backlight charge pump output, and one 1μF for the flash charge pump output. The six constant current sink inputs (D1 to D6) can drive six individual LEDs with a maximum current of 30mA each. The unused sink inputs must be connected to VOUT_BL, otherwise the part will operate only in 2X charge pump mode. The AS2Cwire serial interface enables the backlight charge pump and sets the current sink magnitudes. AS2Cwire addressing allows independent control of two groups of current sink input: D1 to D4 and D5 to D6. Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com 202064A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • June 14, 2012 DATA SHEET AAT2803 Six-Channel White LED Backlight Charge Pump with Flash Constant Current Output Level Settings The constant current sink levels for the white LED backlight (D1 to D6) are set via the serial interface according to a logarithmic scale where each code is 1dB lower than the previous code. In this manner, LED brightness appears linear with each increasing code count. Because the inputs D1 to D6 are true independent constant current sinks, the voltage observed on any single given input will be determined by the actual forward voltage (VF) for the LED being driven. Since the input current sinks are programmable, no PWM (pulse width modulation) or additional control circuitry is needed to control LED brightness. This feature greatly reduces the burden on a microcontroller or system IC to manage LED or display brightness, allowing the user to “set it and forget it.” With its high-speed serial interface (1MHz data rate), the input sink current can be changed successively to brighten or dim LEDs in smooth transitions (e.g., to fade-out) or in abrupt steps, giving the user complete programmability and real-time control of LED brightness. Data 30mA Max IOUT (mA) 20mA Max IOUT (mA) 15mA Max IOUT (mA) 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 30.0 26.7 23.8 21.4 19.0 16.7 15.2 13.3 11.9 10.5 9.5 8.6 7.6 6.7 6.2 0.0 20.0 17.8 15.9 14.3 12.7 11.1 10.2 8.9 7.9 7.0 6.3 5.7 5.1 4.4 4.1 0.0 15.0 13.3 11.9 10.7 9.5 8.3 7.6 6.7 6.0 5.2 4.8 4.3 3.8 3.3 3.1 0.0 The 16 individual current level settings are each approximately 1dB apart (see Current Level Settings table). Code 1 is full scale, Code 15 is full scale attenuated by 14dB, and Code 16 is reserved as a “no current” setting. AS2Cwire Serial Interface The Advanced Simple Serial Control (AS2Cwire) single wire interface is used to set the possible combinations of current levels and LED channel states. AS2Cwire has addressing capability for multiple data registers. With multiple data registers, the backlight charge pump main and sub-channels can be programmed together or independently from one another. AS2Cwire relies on the number of rising edges of the EN/ SET pin to address and load the registers. AS2Cwire latches data or address after the EN/SET pin has been held high for time TLAT. Address or data is differentiated by the number of EN/SET rising edges. Since the data registers are 4 bits each, the differentiating number of pulses is 24 or 16, so that Address 1 is signified by 17 rising edges, Address 2 by 18 rising edges, and so forth. Data is set to any number of rising edges between 1 and including 16. A typical write protocol is a burst of EN/SET rising edges, signifying a particular Address, followed by a pause with EN/SET held high for the TLAT timeout period, a burst of rising edges signifying Data, and a TLAT timeout for the data registers. Once an address is set, then multiple writes to the corresponding data register are allowed. When EN/SET is held low for an amount of time greater than TOFF, the backlight charge pump enters into shutdown mode and draws less than 1μA from the supply. Address 1 is the default address on the first rising edge after the backlight charge pump has been disabled. Whenever shutdown mode is entered, all registers are reset to 1. Table 1: Current Level Settings. Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com 202064A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • June 14, 2012 11 DATA SHEET AAT2803 Six-Channel White LED Backlight Charge Pump with Flash AS2Cwire Serial Interface Timing Address Data T HI T LO TLAT TLAT EN/SET 1 Address 2 17 18 1 1 2... n <= 16 2 Data Reg 1 1 Data Reg 2 1 n AS2Cwire Addressing Max Current and Low Current Registers Five addresses are available to enable all of the part’s functionality. Two 4-bit registers control the main and sub-channels, giving 16 settings for each. The main and sub-channels are programmed to the same constant current level by using Address 1. Use Addresses 2 and 3 to program the main and sub-channels independently. Use Address 4 to program the Max Current register, which sets the Max Current scale. Lastly, Address 5 programs the Low Current register. The Low Current register controls the efficient Low Current mode. When the Max Current register is programmed to 1, 2, or 3, changing the data for Addresses 1-3 will result in the corresponding values found in the Constant Current Programming Levels table. Use the Max Current and Low Current registers to program constant current settings outside of the 20mA Max scale. By default (without changing the Max Current register), the backlight charge pump operates in the 20mA Max scale (see Constant Current Programming Levels). For example, to change to the 30mA Max scale, address the Max Current register with 20 rising edges and pause for TLAT. Program the Max Current register with 2 rising edges and pause for TLAT. The part will next operate in the same Data row, but for the setting found in the 30mA Max column. Next, to change to a different setting on the 30mA Max scale, address the D1-D6 register with 17 rising edges. Program the new constant current level with 1-16 rising edges. The part will update to the new Data setting according to the Constant Current Programming Levels table. When the Max Current register is programmed to 4, the part is programmed to operate in Low Current mode and the Data for Addresses 1-3 is irrelevant. In Low Current mode, the Low Current register takes precedence. See the Low Current Register Settings table below for the current level settings and main/sub-configurations that result. Address EN/SET Edges Addressed Register 1 2 3 4 5 17 18 19 20 21 1&2: D1-D6 Current 1: D1-D4 Current 2: D5-D6 Current 3: Max Current 4: Low Current Table 2: Low Current Register Settings. 12 The backlight charge pump has a distinct Low Current mode with ultra-low quiescent current. For drive currents of 2mA or less, the part operates with significantly reduced quiescent current. This is particularly useful for applications requiring an “always on” condition such as transmissive displays. As an example, to change to Low Current mode, address the Max Current register with 20 rising edges and pause for TLAT. Program the Max Current register with 4 rising edges and pause for TLAT. Address the Low Current register with 21 rising edges and pause for TLAT. Program the Low Current register with 1-16 rising edges. The part will update to the new Low Current mode setting and operate with significantly reduced quiescent current. Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com 202064A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • June 14, 2012 DATA SHEET AAT2803 Six-Channel White LED Backlight Charge Pump with Flash Applications Information Data Max Current 1 2 3 4 20mA Max Scale 30mA Max Scale 15mA Max Scale Low Current Mode Table 3: Max Current Register Settings—Address 4. Data D1-D4 (mA) D5-D6 (mA) 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 0 0 0 0 0 0 0 0 0.05 0.5 1 2 0.05 0.5 1 2 0 0 0 0 0.05 0.5 1 2 0 0 0 0 0.05 0.5 1 2 Table 4: Low Current Register Settings—Address 5. Disabled Current Sinks The backlight charge pump is equipped with an autodisable feature to protect against an LED failure condition. Current sink inputs that are not used should be disabled. To disable and properly terminate unused current sink inputs, they must be tied to VOUT. If left unconnected or terminated to ground, the part will be forced to operate in 2X charge pump mode. Properly terminating unused current sink inputs is important to prevent the charge pump modes from activating prematurely. When properly terminated, only a small sense current flows for each disabled channel. The sense current for each disabled channel is less than 120μA. LED Selection Although the AAT2803 is specifically intended for driving white LEDs, the device can also be used to drive most types of LEDs with forward voltage specifications ranging from 2.0V to 4.7V. LED applications may include main and sub-LCD display backlighting, camera photo-flash applications, color (RGB) LEDs, infrared (IR) diodes for remotes, and other loads benefiting from a controlled output current generated from a varying input voltage. In some instances (e.g., in high-luminous-output applications such as photo flash), it may be necessary to drive high-VF type LEDs. The low-dropout current sinks in the AAT2803 make it capable of driving LEDs with forward voltages as high as 4.7V at full current from an input supply as low as 3.0V. Outputs can be paralleled to drive high-current LEDs without complication. Device Switching Noise Performance The AAT2803 operates at a fixed frequency of approximately 1MHz to control noise and limit harmonics that can interfere with the RF operation of cellular telephone handsets or other communication devices. Back-injected noise appearing on the input pin of the charge pump is 20mV peak-to-peak, typically ten times less than inductor-based DC/DC boost converter white LED backlight solutions. The AAT2803 soft-start feature prevents noise transient effects associated with inrush currents during start-up of the charge pump circuit. Capacitor Selection Careful selection of the six external capacitors CIN, C1, C2, C3, and COUT (for backlight and flash) is important because they will affect turn-on time, output ripple, and transient performance. Optimum performance will be obtained when low equivalent series resistance (ESR) ceramic capacitors are used. In general, low ESR may be defined as less than 100m. A value of 1μF for all four capacitors is a good starting point when choosing capacitors. If the LED current sources are only programmed for light current levels, then the capacitor size may be decreased. Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com 202064A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • June 14, 2012 13 DATA SHEET AAT2803 Six-Channel White LED Backlight Charge Pump with Flash Capacitor Characteristics Ceramic Capacitor Materials Ceramic composition capacitors are highly recommended over all other types of capacitors for use with the AAT2803. Ceramic capacitors offer many advantages over their tantalum and aluminum electrolytic counterparts. A ceramic capacitor typically has very low ESR, is lowest cost, has a smaller PCB footprint, and is nonpolarized. Low ESR ceramic capacitors help maximize charge pump transient response. Since ceramic capacitors are non-polarized, they are not prone to incorrect connection damage. Ceramic capacitors less than 0.1μF are typically made from NPO or C0G materials. NPO and C0G materials typically have tight tolerance and are stable over temperature. Larger capacitor values are typically composed of X7R, X5R, Z5U, or Y5V dielectric materials. Large ceramic capacitors, typically greater than 2.2μF, are often available in low-cost Y5V and Z5U dielectrics, but capacitors greater than 1μF are not typically required. Equivalent Series Resistance ESR is an important characteristic to consider when selecting a capacitor. ESR is a resistance internal to a capacitor that is caused by the leads, internal connections, size or area, material composition, and ambient temperature. Capacitor ESR is typically measured in milliohms for ceramic capacitors and can range to more than several ohms for tantalum or aluminum electrolytic capacitors. 14 Capacitor area is another contributor to ESR. Capacitors that are physically large will have a lower ESR when compared to an equivalent material smaller capacitor. These larger devices can improve circuit transient response when compared to an equal value capacitor in a smaller package size. Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com 202064A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • June 14, 2012 DATA SHEET AAT2803 Six-Channel White LED Backlight Charge Pump with Flash Ordering Information Package Marking1 Part Number (Tape and Reel)2 QFN44-24 OFXYY AAT2803ISK-4.5-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 Information3 QFN44-24 0.4 ± 0.05 24 1 2.7 ± 0.05 0.5 BSC R0.030Max 13 6 12 4.000 ± 0.050 7 2.7 ± 0.05 Top View 0.025 ± 0.025 Bottom View 0.214 ± 0.036 0.900 ± 0.050 4.000 ± 0.050 19 18 0.300 × 45° Pin 1 Identification 0.305 ± 0.075 Pin 1 Dot By Marking Side View All dimensions in millimeters. 1. XYY = assembly and date code. 2. Sample stock is generally held on part numbers listed in BOLD. 3. The leadless package family, which includes QFN, TQFN, DFN, TDFN and STDFN, has exposed copper (unplated) at the end of the lead terminals due to the manufacturing process. A solder fillet at the exposed copper edge cannot be guaranteed and is not required to ensure a proper bottom solder connection. 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. Skyworks may change its documentation, products, services, specifications or product descriptions at any time, without notice. Skyworks makes no commitment to update the materials or information and shall have no responsibility whatsoever for conflicts, incompatibilities, or other difficulties arising from any future changes. No license, whether express, implied, by estoppel or otherwise, is granted to any intellectual property rights by this document. 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Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com 202064A • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • June 14, 2012 15