DATA SHEET AAT2822/2823/2824/2825 TFT-LCD DC/DC Converter with WLED Driver and VCOM Buffer General Description Features The AAT2822-AAT2825 family of integrated panel power solutions provides the regulated voltages required by an active-matrix thin-film transistor (TFT) liquid-crystal display (LCD). The AAT2822 includes a triple-output DC-DC converter, a LED backlight driver, and a VCOM buffer in a 4 mm x 4mm TQFN package. The primary 1.3MHz DC-DC boost converter uses an ultra-small inductor and ceramic capacitor to generate output voltage (VAVDD) of up to 14.5V for the charge pumps. The low on-resistance of the integrated power MOSFET allows for efficiency up to 93%. LCD Bias Power • 2.5V to 5.5V Input Supply Range • 1.3MHz Fixed Frequency Current-Mode Step-Up Regulator • Fast Transient Response • Adjustable Voltage up to 14.5V ▪ ±1% Typical Accuracy • Small External Inductor and Capacitors • Integrated Soft Start and Sequencing of All Rails • Short-Circuit, Over-Voltage, and Over-Temperature Protection The two charge pumps independently regulate a positive output (VGH) and a negative output (VGL). These lowpower outputs use external diode and capacitor stages to regulate output voltages up to +30V and down to -30V. A proprietary regulation algorithm minimizes output ripple when using small capacitors. Positive Output, VGH • Up to 13.2V Input Supply (VDD) • Adjustable Voltage up to 30V @ 20mA ▪ ±3% Typical Accuracy The high efficiency backlight driver provides a constant current output capable of boosting up to 28V. The driver is an ideal power solution for backlight applications with up to seven white LEDs in series or up to 39 white LEDs in a parallel and series configuration. LED brightness is PWM controlled up to 1kHz. Filtered PWM is supported for higher frequencies. The high slew rate operational amplifier is suitable for VCOM buffering and gain adjustment. The sequencing of the power supplies ensures proper panel startup and avoid damage to the device. The AAT2822 family is available in a Pb-free, 24-pin 4 x 4mm TQFN package and operates over the -40°C to +85°C temperature range. Negative Output, VGL • Up to 13.2V Input Supply (VDD) • Adjustable Voltage down to -30V @ 20mA ▪ ± 3% Typical Accuracy WLED Driver • Input Voltage Range: 2.5V to 25V • Maximum Continuous Output: ▪ 12V @ 260mA ▪ 28V @ 50mA • Panel sizes from 5" – 10" ▪ 5.0" 3S5P ▪ 5.6" 3S6P ▪ 7.0" 3S9P ▪ 8.0" 3S10P/11P ▪ 10" 3S13P • Constant LED Current with 6% Accuracy • PWM Dimming Control ▪ Up to 1kHz • 1.3MHz Switching Fixed Frequency ▪ Up to 90% Efficiency VCOM Buffer •High-Performance ▪ 13V/µs Slew Rate ▪ 12MHz, -3dB Bandwidth • ±75mA Output Short-Circuit Current • Low 1.5mA Quiescent Current Applications • Automotive Displays • Digital Photo Frames •Netbooks •PNDs Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com 202081B • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • August 2, 2012 1 DATA SHEET AAT2822/2823/2824/2825 TFT-LCD DC/DC Converter with WLED Driver and VCOM Buffer Typical Application VIN 2.5V - 5.5V VAVDD L1 CIN1 D1 CAVDDOUT RIN LX VIN RFB1 FB RFB2 CIN2 COMP RCOMP CCOMP D3 CDRVN DRVN FBN VGL VDD VDD CDRVP DRVP FBP VGH RFBN1 CVGL CVGH RFBP2 RFBN2 REF CREF CWIN L2 ON OFF EN ON WEN OFF PWM WCOMP VCOM_IN ROP1 ROP2 2 VLED Up to 13 strings WLX ROVP1 CWOUT OVP ROVP2 CWCOMP VAVDD VIN 2.5V - 5.5V D2 WDIM RWCOMP D2 RFBP1 WFB OPIN OP - OUT OP+ AGND PGND1 PGND2 VCOM_OUT RBAL CCOMOUT Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com 202081B • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • August 2, 2012 DATA SHEET AAT2822/2823/2824/2825 TFT-LCD DC/DC Converter with WLED Driver and VCOM Buffer Pin Descriptions Pinout is preliminary and subject to change during development. Pin Number AAT2822 AAT2823 AAT28241 AAT28251 Symbol Function 1 1 n/a n/a WLX O 2 2 2 2 PGND2 I/O 3 3 3 3 REF O 4 4 4 4 FBN I 5 5 n/a n/a WEN I 6 6 6 6 DRVN O 7 7 7 7 VDD PI 8 8 8 8 DRVP O 9 9 9 9 EN I 10 10 10 10 FBP I 11 11 11 11 PGND1 I/O 12 12 12 12 LX O 13 13 13 13 COMP I 14 14 14 14 FB O 15 n/a 15 n/a OPIN I 16 17 18 n/a n/a n/a 16 17 18 n/a n/a n/a OP+ OPOUT I I O 19 19 n/a n/a WCOMP I 20 20 n/a n/a WFB O 21 21 n/a n/a OVP O 22 22 22 22 VIN I 23 23 AGND AGND AGND I/O 24 24 n/a n/a WDIM I 15, 16, 17, 18 EP 1, 19, 20, 21 5, 24, EP 1, 15, 16, 17, 18, 19, 20, 21 5, 24, EP n/a EP Description Boost inductor node. Connect an inductor between IN and WLX. WLX is high impedance in shutdown. Power ground. Connect to GND underneath the IC. Internal reference bypass terminal. Connect a 0.1µF capacitor from this terminal to analog ground (GND). External load capability to 50µA. Negative charge-pump regulator feedback input. Regulates to 0V nominal. Active high logic level enable for WLED Driver. Negative charge-pump driver output. Output high level is VDD, and low level is PGND. Positive and negative charge-pump driver supply voltage. Bypass to PGND with a 0.1µF capacitor. Positive charge-pump driver output. Output high level is VINP, and low level is PGND. Active high logic level enable input. Connect EN to IN for normal operation. Positive charge-pump regulator feedback input. Regulates to 0.6V nominal. Connect feedback resistive divider to analog ground (GND). Power ground. Connect to GND underneath the IC. Main boost regulator power MOSFET N-channel drain. Connect output diode and output capacitor as close to PGND as possible. Step-up regulator error-amplifier compensation point. Connect a series RC from COMP to AGND. Main boost regulator feedback input. Regulates to 0.6V nominal. Connect feedback resistive divider to analog ground (GND) to set output voltage. Operational-amplifier power input. Power supply rail for the operational amplifiers. Typically connected to VAVDD. Bypass OPIN to GND with a 0.1µF capacitor. Operational-amplifier non-inverting input. Operational-amplifier inverting input. Operational-amplifier output. White LED driver error-amplifier compensation point. Connect a series RC from WCOMP to AGND. Feedback pin. Connect a resistor to ground to set the maximum LED current. Feedback pin for over-voltage protection sense. Connect a resistive divider between the boost converter output and ground. Supply input. +2.5V to +5.5V input range. Bypass with a 0.1µF capacitor between IN and GND, as close to the pins as possible. Analog ground. Connect to power ground (PGND) underneath the IC. Dimming control input. Apply a PWM signal up to 1kHz to adjust the WLED brightness from 100% to 5%, proportional to the duty cycle of the PWM signal. N/C Not connected. GND Ground. EP = Exposed paddle, connect to PCB ground plane. 1. Future products. Please contact factory for availability. Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com 202081B • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • August 2, 2012 3 DATA SHEET AAT2822/2823/2824/2825 TFT-LCD DC/DC Converter with WLED Driver and VCOM Buffer Pin Configurations TQFN44-24 (Top View) AAT2822 AAT2823 WCOMP WFB OVP VIN AGND WDIM WCOMP WFB OVP VIN AGND WDIM 16 EP 4 15 5 14 6 13 1 18 2 17 3 14 6 13 12 11 9 10 LX PGND1 FBP EN DRVP VDD N/C N/C N/C VIN AGND GND 19 20 1 18 2 17 3 16 EP 4 15 5 14 6 13 N/C N/C N/C N/C FB COMP 12 11 9 10 8 7 12 11 9 10 LX PGND1 FBP EN DRVP VDD LX PGND1 FBP EN DRVP VDD 21 13 N/C PGND2 REF FBN GND DRVN 22 6 OUT OPOP+ OPIN FB COMP 23 24 19 20 21 22 15 14 8 4 16 5 7 23 24 17 EP N/C N/C N/C N/C FB COMP AAT2825 N/C N/C N/C VIN AGND GND 18 2 4 8 7 LX PGND1 FBP EN DRVP VDD 1 3 15 5 AAT2824 N/C PGND2 REF FBN GND DRVN 16 EP 4 12 11 9 10 8 7 WLX PGND2 REF FBN WEN DRVN 19 3 OUT OPOP+ OPIN FB COMP 20 17 21 18 2 22 1 23 24 19 20 21 22 23 24 WLX PGND2 REF FBN WEN DRVN Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com 202081B • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • August 2, 2012 DATA SHEET AAT2822/2823/2824/2825 TFT-LCD DC/DC Converter with WLED Driver and VCOM Buffer Part Number Descriptions Part Number LCD Bias Startup Sequence Backlight VCOM Buffer AAT2822 AAT2822-1 AAT2823 AAT2823-1 AAT2824 AAT2824-1 AAT2825 AAT2825-1 VAVDD->VGH->VGL VAVDD->VGL->VGH VAVDD->VGH->VGL VAVDD->VGL->VGH VAVDD->VGH->VGL VAVDD->VGL->VGH VAVDD->VGH->VGL VAVDD->VGL->VGH Absolute Maximum Ratings1 Description VIN, EN VDD, OPIN, OUT, OP+, OPLX, WLX WCOMP, COMP, FB, FBP, FBN, REF, WEN, PWM, WFB, OVP DRVP DRVN Value Units -0.3 to 7 -0.3 to 15 -0.3 to 30 -0.3 to VIN + 0.3 -0.3 to (VDD + 0.3) -0.3 to (VDD + 0.3) V Thermal Information2 Symbol ΘJA PD TJ TLEAD Description Thermal Resistance3 Maximum Power Dissipation Operating Junction Temperature Range Maximum Soldering Temperature (at Leads) Value Units 50 2 -40 to 150 300 °C/W W °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. Only one Absolute Maximum Rating should be applied at any one time. 2. Mounted on an FR4 board. 3. Derate 20mW/°C above 25°C. Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com 202081B • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • August 2, 2012 5 DATA SHEET AAT2822/2823/2824/2825 TFT-LCD DC/DC Converter with WLED Driver and VCOM Buffer Electrical Characteristics VIN = 5V, EN = WEN = WDIM = VIN, VAVDD = VDD = 12V, TA = -40°C to 85°C unless otherwise noted. Typical values are at TA = 25°C. Symbol Description Power Supply VIN Input Voltage Range VUVLO Under-Voltage Lockout Threshold UVLOHYS UVLO Hysteresis IIN IN Quiescent Current ISHDN Shutdown Current REF Output Voltage VREF REF Load Regulation REF Current TSD Thermal Shutdown Conditions Min Typ Max Units 5.5 2.5 V V mV mA µA V mV µA 2.5 Rising Edge VFB = VFBP = 0.7V, VFBN = -0.1, LX not switching EN = WEN = Low, ISHDN = IIN + IDD, VDD = 5V No load 0 < ILOAD < 50µA In regulation Temperature rising Hysteresis 2.4 50 1.1 1.182 1.20 1.6 1 1.218 10 50 +140 15 O C Main Step-Up Regulator VAVDD Output Voltage Range FOSC DCMAX Operating Frequency Maximum Duty Cycle VFB FB Regulation Voltage FB Fault Trip Level FB Load Regulation FB Line Regulation FB Input Bias Current RLX(ON) LX On-Resistance ILX LX Leakage Current ILIM LX Current Limit tSS Soft-Start Period Gate High Charge Pump (VGH) VDD VDD Input Supply Range Operating Frequency VFBP FBP Regulation Voltage FBP Fault Trip Level IFBP FBP Input Bias Current DRVPPRDS DRVP PCH ON-Resistance DRVPNRDS DRVP NCH On-Resistance Gate Low Charge Pump (VGL) VDD VDD Input Supply Range Operating Frequency VFBN FBN Regulation Voltage FBN Fault Trip Level IFBN FBN Input Bias Current DRVNPRDS DRVN PCH ON-Resistance DRVNNRDS 6 DRVN NCH On-Resistance VIN VDIODE 910 86 14.5 V 1300 90 1690 kHz % No Load 0.588 0.6 0.612 V VFB falling 0 < IAVDD < full load VIN = 2.5V to 5.5V VFB = 0.7V ILX = 200mA VLX = 13.2V VFB = 0.7V, duty cycle = 75% 0.535 0.546 0.01 0.1 0.557 V %/mA %/V µA mΩ µA A ms ±0.4 +1 700 20 -1 350 0.01 1 1.3 2.7 VFBP Falling VFBP = 0.7V VFBP = 0.585V VFBP = 0.615V 0.588 470 -1 13.2 FOSC 0.6 3 1.5 0.612 530 +1 6 3 20 2.7 VFBN Rising VFBN = -0.1V VFBN = 0.035V VFBN = -0.025V -50 408 -1 13.2 FOSC 0 425 3 1.5 +50 442 +1 6 3 20 Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com 202081B • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • August 2, 2012 V kHz V mV μA Ω Ω kΩ V Hz mV mV μA Ω Ω kΩ DATA SHEET AAT2822/2823/2824/2825 TFT-LCD DC/DC Converter with WLED Driver and VCOM Buffer Electrical Characteristics VIN = 5V, EN = WEN = WDIM = VIN, VAVDD = VDD = 12V, TA = -40oC to 85oC unless otherwise noted. Typical values are at TA = 25oC. Symbol Description Conditions Min Typ Max Units 28 V WLED Driver (AAT2822, AAT2823 Only) VLED IOUT ≥VFB/ ≥VIN RDS(ON) VWFB TSS VIN VDIODE Output Voltage Maximum Continuous Output Current VLED = 28V 50 mA Line Regulation VIN = 2.5V to 5.5V 0.7 %/V Low Side Switch On-Resistance WFB Pin Regulation Soft-Start Time VOVP Over-Voltage Protection Threshold OVHYS Over-Voltage Hysteresis ILIMIT N-Channel Current Limit FPWM Maximum WDIM PWM Frequency DCMIN Minimum Duty Cycle VCOM Buffer (AAT2822 , AAT2824 Only) VOPIN Supply Range IOPIN Supply Current VOS Input Offset Voltage VCM Input Common-Mode Range 0.282 From Enable to Output Regulation; VFB = 300mV VLED Rising VLED Falling 0.55 0.60 25 4.5 1.5 (VNEG, VPOS, VOUT) ≡ VSUP/2 VOL Output Voltage Swing, Low IOUT = -5mA VSUP/2 0 VSUP 150 0.65 13.2 2.5 12 VSUP 75 75 Gain Bandwidth Product Slew Rate VIN = 2.5V Enable Input High Voltage VIN = 5.5V V mA mV V mV mA 12 13 Enable Input Low Voltage V mV A kHz % mV 150 Source Sink mΩ V µs 1 IOUT = 5mA GBW SR Logic WDIM/ WENL/ENL WDIM/ WENH/ENH IEN 300 5 Output Voltage Swing, High Short-Circuit Current 0.318 1.3 VOH ISC 300 0.3 MHz V/µs 0.4 1.4 WDIM/WEN/EN Input Current V 1 Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com 202081B • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • August 2, 2012 V µA 7 DATA SHEET AAT2822/2823/2824/2825 TFT-LCD DC/DC Converter with WLED Driver and VCOM Buffer Typical Characteristics Oscillator Frequency (mHz) Oscillator Frequency vs. Temperature Power Up Sequencing (VAVDD→VGH→VGL; VIN = 5.0V) 1.285 1.280 EN/SET (5V/div) 1.275 1.270 VAVDD (5V/div) 1.265 1.260 1.255 VGH (20V/div) 1.250 1.245 VGL (20V/div) 1.240 1.235 -40 -15 10 35 60 Temperature (°C) 85 Time (500µs/div) Main Boost Efficiency Power Up Sequencing (VOUT = 12V) (VAVDD->VGL->VGH; VIN = 5.0V) 100 90 EN/SET (2V/div) Efficiency (%) 80 VAVDD (2V/div) VGH (10V/div) VGL (10V/div) 70 60 50 40 30 20 10 0 Time (1ms/div) 0 50 100 150 200 250 300 350 400 450 500 Output Current (mA) Line Regulation Main Boost Load Transient (VIN = 5.0V) 12.25 Output Voltage (V) 12.20 VOUT (100mV/div) IOUT (50mA/div) 100mA 12.15 12.10 12.05 12.00 11.95 11.90 11.80 10mA 11.75 2.7 Time (500µs/div) 8 IOUT = 1mA IOUT = 10mA IOUT = 100mA 11.85 3.2 3.7 4.2 4.7 Input Voltage (V) Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com 202081B • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • August 2, 2012 5.2 DATA SHEET AAT2822/2823/2824/2825 TFT-LCD DC/DC Converter with WLED Driver and VCOM Buffer Typical Characteristics VGH vs. Temperature VGH Load Regulation Positive Output Voltage (V) 30.5 30.4 30.3 VGH (V) 30.2 30.1 30.0 29.9 29.8 29.7 29.6 29.5 -40 -15 10 35 60 85 Temperature (°C) 30.5 5.0V 2.7V 30.4 30.3 30.2 30.1 30.0 29.9 29.8 29.7 29.6 29.5 0 2 -29.70 VGL (V) -29.80 -29.90 -30.00 -30.10 -30.20 -30.30 -30.40 35 10 12 14 16 18 20 Load Current (mA) Negative Output Voltage (V) -29.60 10 8 VGL Load Regulation -29.50 -15 6 VGL vs. Temperature -30.50 -40 4 60 85 Temperature (°C) -29.5 -29.6 -29.7 -29.8 -29.9 -30.0 -30.1 -30.2 -30.3 5.0V 2.7V -30.4 -30.5 0 2 4 6 8 10 12 14 16 18 20 Load Current (mA) WLED Efficiency vs. Load Current WLED Operation at 300mA Load (7S3P; VIN = 5V; VL = 12V) (VIN = 5.0V, 3S13P) 90 Efficiency (%) 80 VLED (5V/div) 70 60 50 VOUT (100mV/div) 40 30 ILED (500mA/div) 20 10 0 0 10 20 30 40 50 60 70 Load Current (mA) 80 90 100 Time (200µs/div) Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com 202081B • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • August 2, 2012 9 DATA SHEET AAT2822/2823/2824/2825 TFT-LCD DC/DC Converter with WLED Driver and VCOM Buffer Typical Characteristics VCOM Buffer Supply Current vs. Temperature VCOM Input Offset Voltage vs. Temperature (VIN = 5.0V, VOPIN = 12V) (VIN = 5.0V, VOPIN = 12V) 2.5 Input Offset Voltage (mV) 2.00 1.95 1.90 VGL (V) 1.85 1.80 1.75 1.70 1.65 1.60 1.55 1.50 -40 -15 10 35 Temperature (°C) 60 85 2.0 1.5 1.0 0.5 0.0 -40 -15 10 35 60 Temperature (°C) 10 Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com 202081B • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • August 2, 2012 85 DATA SHEET AAT2822/2823/2824/2825 TFT-LCD DC/DC Converter with WLED Driver and VCOM Buffer Functional Block Diagram AAT2822 LX VIN EN Step-up Controller COMP FB VDD DRVN Charge Pump Control DRVP FBN FBP Reference REF OPIN OPOP+ OP OUT WLX OVP WEN WLED Control WDIM Brightness Control WCOMP WFB AGND PGND1 PGND2 Functional Description The main boost regulator contains a current-mode, fixed-frequency PWM architecture to maximize loop bandwidth and provide fast transient response to pulsed loads typical of TFT-LCD panel source drivers. The 1.3MHz switching frequency allows the use of low profile, low value inductors and ceramic capacitors to minimize the thickness of LCD panel designs. charge pump inverts the supply voltage (VDD) and provides a regulated negative output voltage. The VGH charge pump doubles VDD and provides a regulated positive output voltage. These outputs use external Schottky diodes and capacitor multiplier stages (dependent upon the required output voltage) to regulate up to ±30V. Integrated soft-start circuitry minimizes the start-up inrush current and eliminates output voltage overshoot across the full input voltage range and all load conditions. A constant switching frequency of 1.3MHz minimizes output ripple and capacitor size. Dual Charge-Pump Regulator White LED Backlight Applications The AAT2822 provides low-power regulated output voltages from two individual charge pumps to provide the VGH and VGL supplies. Using a single stage, the VGL The AAT2822 consists of a 1.3MHz fixed-frequency DC/ DC boost controller, and an integrated high voltage MOSFET power switch. A high-voltage rectifier, power Main Boost Converter Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com 202081B • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • August 2, 2012 11 DATA SHEET AAT2822/2823/2824/2825 TFT-LCD DC/DC Converter with WLED Driver and VCOM Buffer inductor, output capacitor, and sense resistors are required to implement a DC/DC constant current boost converter. Integrated soft-start circuitry minimizes the start-up inrush current and eliminates output voltage overshoot across the full input voltage range and all load conditions. The backlight current is set by an external ballast resistor up to a maximum of 260mA at 12V or 50mA at 28V output. Brightness control is via PWM dimming at up to 1kHz. Higher frequencies are achieved by filtered PWM. The AAT2822 can drive from 3 LEDs in series up to a maximum of 7 LEDs, making it suitable for screen sizes from 5” up to 10”. Depending upon the number of LEDs required, up to 9 parallel strings can be successfully driven. If the OVP input voltage is exceeded the WLED driver continues to regulate at the OVP threshold. Start EN High VCOM Buffer: Operational Amplifier The operational amplifier drives the LCD backplane VCOM. The operational amplifier features +/- 75mA(min) output short-circuit current, 13V/μs slew rate, and 12MHz bandwidth. Internal short-circuit protection limits the short circuit current while the output is directly shorted. Power Supply Sequencing The AAT2822 family has integrated power supply sequencing to prevent damage to the LCD screen. Two sequences are available to swap the startup of the positive and negative gate drive voltages. The startup sequence for the “-1” option establishes main boost supply (VAVDD) first, followed by the gate voltages VGL then VGH. The sequence for the plain option is to establish VAVDD first followed by VGH then VGL. The WLED backlight driver is independently controlled by WEN and WDIM. Operating Faults No Yes The AAT2822 family continuously monitors for fault conditions on the main boost converter and charge pumps according to defined fault trip levels. During operation if any fault conditions persist the controller will shut down all supplies. After removing the fault conditions, recycle the enables to start up the supplies. WLED Boost VWLED > VOVP No Yes Stop Switching Figure 1: WLED Driver Operation. 12 Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com 202081B • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • August 2, 2012 DATA SHEET AAT2822/2823/2824/2825 TFT-LCD DC/DC Converter with WLED Driver and VCOM Buffer Application Information Start Main Step-Up Converter Output Capacitor The high output ripple inherent in the boost converter necessitates low impedance output filtering. Multi-layer ceramic (MLC) capacitors provide small size and adequate capacitance, low parasitic equivalent series resistance (ESR) and equivalent series inductance (ESL), and are well suited for use with the primary step-up converter. MLCs of type X7R or X5R are recommended to ensure good capacitance stability over the full operating temperature range. EN High No Yes MAIN BOOST VFB > FB Fault Trip Level and Persist The output capacitor is sized to maintain the output load without significant voltage droop during the power switch ON interval, when the output diode is not conducting. And because the VGH, VGL also have their input power from the main step-up converter output, the output capacitor may also decrease the inrush current during VGH and VGL start up. A ceramic output capacitor with a minimum value of 22µF is recommended. For inrush current sensitive applications, two 22µF are recommended. Typically, 25V rated ceramic capacitors are required for the 24V boost output. Ceramic capacitors sized as small as 0805 are available which meet these requirements. MLCs exhibit significant capacitance reduction with applied voltage. Output ripple measurements should confirm that output voltage droop is acceptable. No Yes NEGATIVE CP VFBN > FBN Fault Trip Level and Persist No Yes POSITIVE CP V FBP > FBP Fault Trip Level and Persist Input Capacitor No Yes Shut-Down Main Boost, Negative CP, and Positive CP OPAMP Start-Up Sequence Complete No EN Low Figure 2: Startup Sequence for AAT282X-11. 1. For AAT282x the startup sequence is positive charge pump followed by the negative charge pump. The boost converter input current flows during both ON and OFF switching intervals. The input ripple current is less than the output ripple and, as a result, less input capacitance is required. However, the AAT2822 input voltage is shared among other channels; a ceramic input capacitor from 4.7µF to 10µF is recommended. Minimum 6.3V rated ceramic capacitors are required at the input. Ceramic capacitors sized as small as 0603 are available which meet these requirements. Large capacitance tantalum or solid-electrolytic capacitors may be necessary to meet stringent output ripple and transient load requirements. These can replace (or be used in parallel with) ceramic capacitors. Both tantalum and OSCON-type capacitors are suitable due to their low ESR and excellent temperature stability (although they exhibit much higher ESR than MLCs). Aluminumelectrolytic types are less suitable due to their high ESR Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com 202081B • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • August 2, 2012 13 DATA SHEET AAT2822/2823/2824/2825 TFT-LCD DC/DC Converter with WLED Driver and VCOM Buffer characteristics and temperature drift. Unlike MLCs, these types are polarized and proper orientation on input and output pins is required. 30% to 70% voltage derating is recommended for tantalum capacitors. Selecting the Schottky Diode To ensure minimum forward voltage drop and no recovery, high voltage Schottky diodes are the best choice for the primary step-up converter. The output diode is sized to maintain acceptable efficiency and reasonable operating junction temperature under full load operating conditions. Forward voltage (VF) and package thermal resistance (θJA) are the dominant factors to consider in selecting a diode. The diode’s published current rating may not reflect actual operating conditions and should be used only as a comparative measure between similarly rated devices. 20V rated Schottky diodes are recommended for outputs less than 15V, while 30V rated Schottky diodes are recommended for outputs greater than 15V. The average diode current is equal to the output current: IAVG < IOUT The average output current multiplied by the forward diode voltage determines the loss of the output diode. PLOSS_DIODE = IAVG · VF = IOUT · VF Diode junction temperature can be estimated: TJ = TA + θJA · PLOSS_DIODE The junction temperature should be maintained below 110°C, but may vary depending on application and/or system guidelines. The diode θJA can be minimized with additional PCB area on the cathode. PCB heat sinking the anode may degrade EMI performance. The reverse leakage current of the rectifier must be considered to maintain low quiescent (input) current and high efficiency under light load. The rectifier's reversed current increases dramatically at high temperatures. Selecting the Main Step-Up Inductor The primary step-up converter is designed to operate with a 2.2μH inductor for all input and output voltage combinations. The inductor saturation current rating should be greater than the NMOS current limit. If necessary, the peak inductor current can exceed the saturation level by a small amount with no significant effect on performance. The maximum duty cycle can be estimated from the relationship for a continuous mode boost con- 14 verter. Maximum duty cycle (DMAX) is the duty cycle at minimum input voltage (VIN(MIN)). DMAX = (VOUT + VF - VIN(MIN)) VOUT + VF Where VF is the Schottky diode forward voltage and can be estimated at 0.5V. Manufacturer’s specifications list both the inductor DC current rating, which is a thermal limitation, and peak inductor current rating, which is determined by the saturation characteristics. Measurements at full load and high ambient temperature should be completed to ensure that the inductor does not saturate or exhibit excessive temperature rise. The output inductor (L) is selected to avoid saturation at minimum input voltage, maximum output load conditions. Peak current may be calculated from the following equation, again assuming continuous conduction mode. Worst-case peak current occurs at minimum input voltage (maximum duty cycle) and maximum load. Switching frequency (Fs) is at 1.3MHz with a 2.2µH inductor. IPEAK = IOUT D · VIN(MIN) + MAX 1 - DMAX 2 · FS · L The RMS current flowing through the boost inductor is equal to the DC plus AC ripple components. Under worst-case RMS conditions, the current waveform is critically continuous. The resulting RMS calculation yields worst-case inductor loss. The RMS value should be compared against the manufacturer’s temperature rise or thermal derating guidelines. IRMS = IPEAK 3 For a given inductor type, smaller inductor size leads to an increase in DCR winding resistance and, in most cases, increased thermal impedance. Winding resistance degrades boost converter efficiency and increases the inductor operating temperature. PLOSS_INDUCTOR = IRMS2 · DCR Setting the Output Voltage The resistive divider network R2 and R3 of Figure 7 programs the output to regulate at a voltage higher than 0.6V as shown in Table 1. To limit the bias current required for the external feedback resistor string while maintaining good noise immunity, the minimum sug- Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com 202081B • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • August 2, 2012 DATA SHEET AAT2822/2823/2824/2825 TFT-LCD DC/DC Converter with WLED Driver and VCOM Buffer gested value for R3 is 6.04kΩ. The resistive divider can be calculated in the following equation: R3 = R2 · VAVDD VFB -1 = R2 · VAVDD 0.6V - 1 VAVDD (V) R3 = 6.04kΩ R2 (kΩ) R3 = 59kΩ R2 (MΩ) 9 10 11 12 13 15 20 22 24 84.5 93.1 105 115 124 143 196 215 237 0.825 0.931 1.02 1.13 1.21 1.4 1.1 2.1 2.3 Table 1: Setting the Output Voltage for the Main Step-Up Converter. Selecting Compensation Components The AAT2822 main boost architecture uses peak current mode control to eliminate the double pole effect of the output L&C filter and simplifies compensation loop design. The current mode control architecture simplifies the transfer function of the control loop to a one-pole, one left plane zero and one right half plane (RHP) system in frequency domain. The dominant pole can be calculated by: fP = 1 2π · RO · C6 The ESR zero of the output capacitor can be calculated by: 1 fZ_ESR = 2π · RESR · C6 Where: C6 is the output filter capacitor RO is the load resistor value RESR is the equivalent series resistance of the output capacitor. The right half plane (RHP) zero can be determined by: VIN2 fZ_RHP = 2π · L1 · IAVDD · VAVDD It is recommended to design the bandwidth to one decade lower than the frequency of RHP zero to guarantee the loop stability. A series capacitor and resistor network (R11 and C8) connected to the COMP pin sets the pole and zero which are given by: fP_COM = 1 2π · REA · C8 fZ_COM = 1 2π · R11 · C8 Where: C8 is the compensation capacitor R11 is the compensation resistor REA is the output resistance of the error amplifier (MΩ). A 100pF capacitor and a 200kΩ resistor in series are chosen for optimum phase margin and fast transient response. Charge Pump The number of charge pump stages required for a given output (VGH) varies with the input voltage applied (VAVDD) from the main boost. A lower input voltage requires more stages for a given output. If the numbers of stages increases, the maximum load current limitation of the charge pump would be decreased to maintain output voltage regulation. The number of stages required can be estimated by: nP = VGH - VAVDD(MIN) VAVDD(MIN) - 2VF for the positive output and nN = VGL 2VF - VAVDD(MIN) for the negative output where VF = 0.31V is the forward voltage of the BAT54 Schottky diode at 4mA forward current. When solving for np and nn, round up the solution to the next highest integer to determine the number of stages required. Negative Output Voltage (VGL) The negative output voltage is adjusted by a resistive divider from the output (VON) to the FBN and REF pins. The maximum reference voltage current is 200µA; therefore, the minimum allowable value for R10 of Figure Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com 202081B • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • August 2, 2012 15 DATA SHEET AAT2822/2823/2824/2825 TFT-LCD DC/DC Converter with WLED Driver and VCOM Buffer 6 is 6.04kΩ. It is best to select the smallest value possible for R10, as this will keep the value of R9 to a minimum. With R10 selected, R9 can be determined: VGL VGL R9 = V · R10 = 1.2V · R10 REF Positive Output Voltage (VGH) The positive output voltage is set by a resistive divider from the output (VGH) to the FBP and ground pins. Limiting the value of R7 to 6.04kΩ or lower reduces noise in the feedback circuit. Once R7 has been determined, solve for R6: R6 = R7 · VGH VGH - 1 = R7 · -1 VFBP 0.6V Flying and Output Capacitors The minimum value for the flying capacitor is limited by the output power requirement, while the maximum value is set by the bandwidth of the power supply. If CFLY is too small, the output may not be able to deliver the power demanded, while too large of a capacitor may limit the bandwidth and time required to recover from load and line transients. A 0.1µF X7R or X5R ceramic capacitor is typically used. The voltage rating of the flying and reservoir output capacitors varies with the number of charge pump stages. The reservoir output capacitor value should be roughly 10 times the value of the flying capacitor. Use larger capacitors for reduced output ripple. positive and negative charge pumps (regardless of the number of stages) is: VREVERSE = VIN - VF The BAT54SDW quad Schottky diode in a SOT363 (2x2mm) package is a good choice for multiple-stage charge pump configuration. White LED Driver The white LED backlight driver can be enabled when input supply rises above under voltage lockout threshold. To reduce inrush current it is recommended that the main boost and white LED driver are not enabled concurrently. Over-Voltage Protection (OVP) with Open Circuit Failure The OVP protection circuit consists of a resistor network tied from the output voltage to the OVP pin (see Figure 3). To protect the device from open circuit failure, the resistor divider can be selected such that the over-voltage threshold occurs prior to the output reaching VLED+(MAX). The value of R5 should be selected from 10kΩ to 20kΩ to minimize losses without degrading noise immunity. R4 = R5 · VLED+(MAX) VLED+(MAX) VOVP -1 = 10kΩ · 0.6V -1 D2 VWLX VLED C5 Input Capacitor The primary function of the input capacitor is to provide a low impedance loop for the edges of pulsed current drawn by the IC. A low ESL X7R or X5R type ceramic capacitor is ideal for this function. The size required will vary depending on the load, output voltage, and input voltage characteristics. Typically, the input capacitor value should be 5 to 10 times the value of the flying capacitor. If the source impedance of the input supply is high, a larger capacitor may be required. To minimize stray inductance, the capacitor should be placed as closely as possible to the IC. This keeps the high frequency content of the input current localized, minimizing radiated and conducted EMI. Rectifier Diodes For the rectifiers, use Schottky diodes with a voltage rating of 1.5 times the input voltage. The maximum steadystate voltage seen by the rectifier diodes for both the 16 L2 R4 C4 WLX OVP WFB R8 0.3V VIN R5 0.6V Figure 3: Over-Voltage Protection Circuit. OVP Constant Voltage Operation Under closed loop constant current conditions, the output voltage is determined by the operating current, LED forward voltage characteristics (VFLED), quantity of series connected LEDs (N), and the feedback pin voltage (VFB). VOUT = VFB + N · VFLED Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com 202081B • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • August 2, 2012 DATA SHEET AAT2822/2823/2824/2825 TFT-LCD DC/DC Converter with WLED Driver and VCOM Buffer When the rising OVP threshold is exceeded, switching is stopped and the output voltage decays. Switching automatically restarts when the output drops below the lower OVP hysteresis voltage (100mV typical), and as a result the output voltage increases. The cycle repeats, maintaining an average DC output voltage proportional to the average of the rising and falling OVP levels (multiplied by the resistor divider scaling factor). High operating frequency and low output voltage ripple ensure DC current and negligible flicker in the LED string(s). While OVP is active, the maximum LED current programming error (ΔILED) is proportional to voltage error across an individual LED (ΔVFLED). ∆VFLED = N · VFLED(TYP) - VOVP(MIN) - VWFB N To minimize the ΔILED error, the minimum OVP voltage (VOVP(MIN)) may be increased, yielding a corresponding increase in the maximum OVP voltage (VOVP(MAX)). VF is the Schottky diode D2 forward voltage at turn-OFF. VRING is the voltage ring occurring at turn-OFF. White LED Selection and Current Setting The WLED current is controlled by the WFB voltage and the ballast resistor (R8). For maximum accuracy, a 1% tolerance resistor is recommended. The ballast resistor (R8) value can be calculated as follows: R8 = VWFB(MAX) ILED(MAX) Where VWFB = 0.3V For example, if the maximum current for each string of 3 series LEDs is 20mA, the maximum current for a 10 inch panel (3S13P) is 260mA (20mA x 13), which corresponds to a minimum resistor value of 1.15Ω R8(Ω) 30 25 20 15 10 5 0.768 0.909 1.15 1.54 2.32 4.64 Table 2: Maximum LED Current and Ballast Resistor (R8) Values for 10” Panel Size. Typical white LEDs are driven at maximum continuous currents of 15mA to 20mA. The maximum number of series-connected LEDs is determined by the minimum output voltage of the boost converter (VLED), minus the maximum feedback voltage (VWFB(MAX)) divided by the maximum LED forward voltage (VFLED(MAX)) which can be estimated from the manufacturers’ datasheet at the maximum LED operating current. VLED = VOVP(TYP) · Measurements should confirm that the maximum switching node voltage (VWLX(MAX)) is less than 30V under worst case operating conditions. R2 VWLX(MAX) = VOVP(MAX) · R + 1 + VF + VRING 1 Maximum ILED Current (mA) N= R5 R4 + 1 VOVP(MIN) - VWFB(MAX) VFLED(MAX) For example, the typical forward voltage of the white LED is 3.5V at 20mA. R5 464kΩ VLED = VOVP(TYP) · R + 1 = 0.6V · + 1 = 27.8V 10kΩ 4 N= VOVP(MIN) - VWFB(MAX) 27.8V - 0.6V = = 7.8 LEDs VFLED(MAX) 3.5V Therefore, under these typical operating conditions, 7 LEDs can be used in series for each string. PWM Dimming Control The dimming of the white LED can be controlled using a PWM or a filter PWM signal. By connecting a PWM signal to the WDIM pin and adjusting the duty cycle of the PWM signal, the dimming of the white LED changes proportionally to the percentage of the duty cycle as shown in Figure 4. However, the dimming control using PWM connected to the WDIM pin can operate at a frequency up to 1kHz. 0.3V R8 = 260mA = 1.15Ω Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com 202081B • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • August 2, 2012 17 DATA SHEET AAT2822/2823/2824/2825 TFT-LCD DC/DC Converter with WLED Driver and VCOM Buffer R21 0 R8 adj adj R21 4.99k Connect WDIM to VIN 24 23 22 21 20 19 18 17 16 15 14 13 R23 4.99k C25 0.1µF 1 WLX 2 PGND2 3 FBN AAT2822 WEN DRVN 18 N/C 17 N/C 16 N/C 15 N/C 14 FB 13 COMP 7 8 9 10 11 12 7 8 9 10 11 12 VDD DRVP EN FBP PGND1 LX N/C N/C AAT2822 N/C FBN N/C WEN FB DRVN COMP R22 28k WDIM AGND VIN OVP WFB WCOMP 1 WLX 2 PGND2 3 HF-PWM VDD DRVP EN FBP PGND1 LX WDIM AGND VIN OVP WFB WCOMP 24 23 22 21 20 19 PWM R8 Figure 4: PWM Dimming Control. Figure 5: Low-Pass Filter PWM Dimming Control. For applications requiring a PWM frequency higher than 1KHz, an external filter PWM is connected to the WFB pin to control the dimming of the white LED. This low-pass filter (R23/C25) integrates the high frequency PWM signal to produce a DC dimming control as shown in Figure 5. When the PWM duty cycle is adjusted, the DC voltage across the ballast resistor (R8) changes, resulting in change of the white LED current. Apply the KCL at the feedback node (WFB). The voltage across the R8 resistor can be expressed: VR8 = 0.3V - R21 · (VC25 - 0.3V) R22 For minimum dimming, VR8 = 0V. 18 Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com 202081B • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • August 2, 2012 DATA SHEET AAT2822/2823/2824/2825 TFT-LCD DC/DC Converter with WLED Driver and VCOM Buffer Choose R21 = 4.99kΩ and VC25 = 2V, and solve for R22: R22 = R21 = 28kΩ (0.3V - VR8) · (VC25 - 0.3V) The low-pass filter should be chosen to produce an acceptable ripple for the DC dimming voltage and a small time constant. For application where the PWM frequency is greater than 10KHz, the optimum values for the low-pass filter are R23 = 4.99kΩ and C25 = 0.1µF. Selecting the Schottky Diode To ensure minimum forward voltage drop and no recovery, high-voltage Schottky diodes are considered the best choice for the WLED boost converter. The output diode is sized to maintain acceptable efficiency and reasonable operating junction temperature under full load operating conditions. Forward voltage (VF) and package thermal resistance (θJA) are the dominant factors to consider in selecting a diode. The diode's non-repetitive peak forward surge current rating (IFSM) should be considered for high pulsed load applications such as camera flash. The IFSM rating drops with increasing conduction period. Manufacturers’ datasheets should be consulted to verify reliability under peak load conditions. The diode’s published current rating may not reflect actual operating conditions and should be used only as a comparative measure between similarly rated devices. 40V rated Schottky diodes are recommended for outputs less than 30V, while 60V rated Schottky diodes are recommended for outputs greater than 35V. The average diode current is equal to the output current: IAVG = IOUT The average output current multiplied by the forward diode voltage determines the loss of the output diode. PLOSS_DIODE = IAVG · VF = IOUT · VF Diode junction temperature can be estimated: TJ = TA + θJA · PLOSS_DIODE Output diode junction temperature should be maintained below 110°C, but may vary depending on application and/or system guidelines. The diode θJA can be minimized with additional PCB area on the cathode. PCB heat-sinking the anode may degrade EMI performance. The reverse leakage current of the rectifier must be considered to maintain low quiescent (input) current and high efficiency under light load. The rectifier's reverse current increases dramatically at elevated temperatures. Selecting the WLED Step-Up Inductor The WLED step-up converter has the same topology as the main step-up converter. It is designed to operate with a 2.2μH inductor for all input and output voltage combinations. The inductor saturation current rating should be greater than the NMOS current limit. DMAX = (VOUT + VF - VIN(MIN)) VOUT + VF The output inductor (L) is selected to avoid saturation at minimum input voltage and maximum output load conditions. Peak current may be calculated from the following equation, again assuming continuous conduction mode. Worst-case peak current occurs at minimum input voltage (maximum duty cycle) and maximum load. Switching frequency is estimated at 1.3MHz with a 2.2µH inductor. IPEAK = IOUT D · VIN(MIN) + MAX 1 - DMAX 2 · FS · L Selecting the WLED Step-Up Capacitors The high output ripple inherent in the boost converter necessitates low impedance output filtering. Multi-layer ceramic (MLC) capacitors provide small size and adequate capacitance, low parasitic equivalent series resistance (ESR) and equivalent series inductance (ESL), and are well suited for use with the WLED boost regulator. MLC capacitors of type X7R or X5R are recommended to ensure good capacitance stability over the full operating temperature range. The output capacitor is sized to maintain the output load without significant voltage droop (ΔVOUT) during the power switch ON interval, when the output diode is not conducting. A ceramic output capacitor with a value of 2.2μF to 4.7μF is recommended. Typically, 50V rated capacitors are required for the 28V maximum boost output. Ceramic capacitors sized as small as 0805 or 1206 are available which meet these requirements. MLC capacitors exhibit significant capacitance reduction with applied voltage. Output ripple measurements should confirm that output voltage droop and operating stability are acceptable. Voltage derating can minimize this factor, but results may vary with package size and among specific manufacturers. Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com 202081B • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • August 2, 2012 19 DATA SHEET AAT2822/2823/2824/2825 TFT-LCD DC/DC Converter with WLED Driver and VCOM Buffer The output capacitor size can be estimated using the equation: COUT = IOUT · DMAX FS · ∆VOUT To maintain stable operation at full load, the output capacitor should be sized to maintain ΔVOUT between 100mV and 200mV. The WLED boost converter input current flows during both ON and OFF switching intervals. The input ripple current is lower than the output ripple and, as a result, a lower input capacitance is required. 20 LCD VCOM Buffer The VCOM buffer is designed to drive the voltage on the backplane of an LCD display. The buffer must be capable of sinking and sourcing capacitive pulse current at low frequency. A 10nF ceramic output capacitor in series with a 100Ω resistor is sufficient for buffer stability at high frequencies. The VCOM output voltage is typically set to half of the main boost output voltage VADD. The maximum input bias voltage for the VCOM buffer (VOPIN) cannot exceed 13V. In applications where the main boost output voltage VVADD is greater than 13V, VOPIN should be connected to an external supply to prevent damage to the device; the jumper J7 should be left open to disconnect VAVDD from VOPIN. Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com 202081B • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • August 2, 2012 DATA SHEET AAT2822/2823/2824/2825 TFT-LCD DC/DC Converter with WLED Driver and VCOM Buffer WLED- VIN 10V C1 4.7μF VIN-WLED R20 0Ω J3 C4 HF-PWM R1 0Ω VIN adj 10V C2 0.1μF PWM R21 0Ω OVP 10μF 16V 17 16 R14 R13 15 10kΩ 19 20 21 OVP WFB WCOMP VOPIN C22 0.1μF 13 R11 LX 200kΩ LX C8 100pF D1 C13 0.1μF 50V BAT54SDW A3 1 stage4 C12 C20 0.22μF 50V 6 C21 0.22μF 50V C14 0.1μF 50V 5 4 3 BAT54SDW 0.6V R6 VIN J1 FBP C26 R18 open A1 C10 3 4 C11 6 1 VAVDD VIN AVDD C16 0.22μF 25V J8 stage2 2 C17 0.22μF 50V BAT54SDW A4 3 J9 4 0.1μF 50V C28 R19 VIN 5 0.1μF 50V C27 VDD 0Ω C15 0.1μF 50V Adj 10pF R7 6.04kΩ 25V EN DRVP 0.1μF 25V 2 stage 3 VAVDD 1 2 J5 C3 10μF 10V L1 2.2μH stage3 1 2 C19 0.22μF 50V 3 1 2 Adj R3 6.04kΩ C6 22μF 25V 0.1μF 25V 5 J7 0.6V R2 14 5 6 1 C29 0.22μF J10 stage4 50V 1 2 1 2 stage 2 C18 0.22μF 25V 6 4 1 2 COMP 18 C23 0.1μF 25V 2 1 1 2 R16 open 0Ω R15 10kΩ 12 7 J2 WEN J6 22 FB DRVN C25 open VDD A2 J4 OP+ OPIN WEN DRVN VIN 23 WDIM FBN PGND1 6 0V AAT2822 REF FBP R9 Adj 5 11 VGL (negative) 4 OP- 10 FBN R10 6.04kΩ C7 OUT R23 open C9 100Ω 8nF R17 U1 PGND2 VDD 0.22μF 6.3V 3 WLX EN 1.2V VIN 24 2 DRVP 1 C5 2.2μF 50V AGND D2 WLED+ 9 R4 adj R12 AGND L2 2.2μH WLX 0.6V 8 R5 R22 open C24 10nF 17.4kΩ OVP 10kΩ WFB R8 0.1μF 50V VGH (positive) 2 BAT54SDW C30 0.22μF 50V Figure 6: AAT2822IBK Evaluation Board Schematic. Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com 202081B • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • August 2, 2012 21 DATA SHEET AAT2822/2823/2824/2825 TFT-LCD DC/DC Converter with WLED Driver and VCOM Buffer Component Part Number Description Manufacturer U1 AAT2822IBK C1 C2 C3, C4 C5 C6 C7 C8 C9 C10, C12, C22, C23 C11, C13, C14, C15, C27, C28 C16, C18 C17, C19, C20, C21, C29, C30 C24 C25 C26 A1, A2, A3, A4 D1, D2 L1, L2 GRM188R61A475K GRM188R71C104K GRM21BR61C106K GRM31CR71H225K GRM31CR61C226M GRM188R71A224K GRM1885C1H101J GRM2195C1H822J GRM188R61E104K TFT-LCD DC-DC Converter with WLED Driver and VCOM Buffer CAP CERAMIC 4.7μF 0603 X5R 10V 10% CAP CERAMIC 0.1μF 0603 X7R 16V 10% CAP CERAMIC 10μF 0805 X5R 16V 10% CAP CERAMIC 2.2μF 1206 X7R 50V 10% CAP CERAMIC 22μF 1206 X5R 16V 20% CAP CERAMIC 0.22μF 0603 X7R 10V10% CAP CERAMIC 100pF 0603 COG 50V 5% CAP CERAMIC 8nF 0805 X7R 50V 10% CAP CERAMIC 0.1μF 0603 X5R 25V 10% GRM188R71H104K CAP CERAMIC 0.1μF 0603 X7R 50V 10% GRM188R61E224K CAP CERAMIC 0.22μF 0603 X5R 25V10% GRM21BR71H224K CAP CERAMIC 0.22μF 0805 X7R 50V10% GRM188R71H103K NC GRM1885C1H100J BAT54SDW-7-F SS16L CDRH5D16-2R2 CAP CERAMIC 10nF 0603 X7R 50V 10% CAP CERAMIC 10pF 0603 COG 50V 5% Schottky Diode Array 30V SC70-6 Schottky Diode 1A 60V Micro SMP POWER INDUCTOR 2.2μH 3.0A SMD Adjustable Value (See Equations.1 – 5 and Table 5); 0603 Res 6.04kΩ 1/10W 1% 0603 SMD Res 10kΩ 1/10W 1% 0603 SMD Res 200kΩ 1/10W 1% 0603 SMD Res 17.4kΩ 1/10W 1% 0603 SMD Res 0Ω 1/10W 1% 0603 SMD Res 100Ω 1/10W 1% 0603 SMD R2, R4, R6, R8, R9 R3, R7, R10 R5, R13, R14 R11 R12 R15, R19, R20, R21 R17 R18, R22, R23, R25 RC0603FR-0760K4L RC0603FR-0710KL RC0603FR-07200KL RC0603FR-0717K4L RC0603FR-070RL RC0603FR-07100RL NC Skyworks Murata Diode Inc Taiwan Semiconductor Sumida Yageo Table 3: AAT2822IBK Evaluation Board Bill Of Materials (BOM). Panel Sizes (inches) WLED Matrix (Series and Parallel) Ballast Resistor R8 (Ω) 5 5.6 7 8 10 5 3S5P 3S6P 3S9P 3S10P/11P 3S13P 7S2P 2.37 2.0 1.3 1.2 1.0 4.7 Table 4: Ballast Resistor Selection for Different Panel Sizes. Eq. 1: R2 = R3 · VAVDD VAVDD VFB -1 = 6.04kΩ · 0.6V -1 VGL VGL Eq. 2: R9 = VFBN · R10 = 1.2V · 6.04kΩ Eq. 3: R6 = R7 · 22 VGH VGH - 1 = 6.04kΩ · -1 VFBP 0.6V Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com 202081B • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • August 2, 2012 DATA SHEET AAT2822/2823/2824/2825 TFT-LCD DC/DC Converter with WLED Driver and VCOM Buffer VLED+(MAX) VLED+(MAX) VOVP -1 = 10kΩ · 0.6V -1 Eq. 4: R4 = R5 · VWFB(MAX) 0.3V ILED(MAX) = ILED(MAX) Eq. 5: R8 = WLED- VIN 10V C1 4.7μF VIN-WLED R20 0Ω J3 C4 HF-PWM R1 0Ω VIN adj 10V C2 0.1μF PWM 10μF 16V 20 19 WCOMP 22 21 OVP WFB 13 0.6V R2 R11 200kΩ LX PGND1 15 LX C8 100pF D1 3 C13 0.1μF 50V BAT54SDW A3 1 C20 0.22μF 50V 6 C21 0.22μF 50V C14 0.1μF 50V 5 4 3 BAT54SDW 0.6V R6 VIN J1 FBP C26 R18 open A1 C10 3 4 C11 6 1 VAVDD VIN AVDD C16 0.22μF 25V J8 stage2 2 C17 0.22μF 50V BAT54SDW A4 3 J9 4 0.1μF 50V C28 R19 VIN 5 0.1μF 50V C27 VDD 0Ω C15 0.1μF 50V Adj 10pF R7 6.04kΩ 25V EN DRVP 0.1μF 25V 2 stage 3 stage4 C12 1 2 J5 VAVDD stage3 1 2 C19 0.22μF 50V L1 2.2μH C6 22 μF 25V 0.1μF 25V 5 Adj R3 6.04kΩ C3 10μF 10V 5 6 1 C29 0.22μF J10 stage4 50V 1 2 1 2 stage 2 C18 0.22μF 25V 6 4 1 2 16 14 C23 0.1μF 25V 2 1 1 2 17 12 7 J2 WEN J6 COMP 18 VDD A2 J4 23 DRVN DRVN VIN N/C FB FBP 0V N/C WEN 11 R9 Adj 6 FBN EN VGL (negative) 5 AAT2823 9 4 R10 6.04kΩ C7 N/C N/C REF C9 8nF U1 PGND2 VDD 0.22μF 6.3V 3 FBN WLX 10 2 1.2V VIN 24 WDIM 1 C5 2.2μF 50V AGND D2 C25 open R12 DRVP R4 adj WLED+ R23 open 17.4kΩ AGND L2 2.2μH WLX 0.6V 8 R5 R22 open R21 0Ω OVP OVP 10kΩ WFB R8 0.1μF 50V VGH (positive) 2 BAT54SDW C30 0.22μF 50V Figure 7: AAT2823IBK Evaluation Board Schematic. Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com 202081B • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • August 2, 2012 23 DATA SHEET AAT2822/2823/2824/2825 TFT-LCD DC/DC Converter with WLED Driver and VCOM Buffer VIN 10V C1 4.7μF R1 0Ω 10V C2 0.1μF C24 10nF 100Ω R17 FBN 19 20 N/C 22 21 VIN N/C 15 10kΩ VOPIN C22 0.1μF 13 R11 LX 200kΩ LX C8 100pF D1 J5 3 C13 0.1μF 50V BAT54SDW A3 1 stage4 C12 C20 0.22μF 50V 6 C21 0.22μF 50V C14 0.1μF 50V 5 4 3 BAT54SDW 0.6V R6 VIN J1 FBP DRVP C26 R18 open A1 C10 3 4 C11 6 1 VAVDD VIN AVDD C16 0.22μF 25V J8 stage2 2 C17 0.22μF 50V BAT54SDW A4 3 J9 4 0.1μF 50V C28 R19 VIN 5 0.1μF 50V C27 VDD 0Ω C15 0.1μF 50V Adj 10pF R7 6.04kΩ 25V EN 0.1μF 25V 2 stage 3 VAVDD stage3 1 2 4 C3 10μF 10V L1 2.2μH C6 22 μF 25V 0.1μF 25V 5 1 2 Adj R3 6.04kΩ 1 2 6 J7 0.6V R2 14 12 PGND1 R14 R13 5 6 1 0.1μF 50V C29 0.22μF 50V VGH (positive) 2 BAT54SDW J10 stage4 1 2 1 2 stage 2 C18 0.22μF 25V C19 0.22μF 50V 1 2 COMP 18 17 16 C23 0.1μF 25V 2 1 1 2 11 7 J2 WEN J6 open 0Ω R15 10kΩ VDD A2 J4 FBP FB DRVN DRVN VIN OP+ OPIN WEN EN 6 0V AAT2824 REF 9 R9 Adj 5 OP- VDD VGL (negative) 4 OUT PGND2 10 FBN R10 6.04kΩ C7 R16 U1 N/C 8 0.22μF 6.3V 3 N/C 24 N/C 2 DRVP 1 1.2V AGND 23 AGND C30 0.22μF 50V Figure 8: AAT2824IBK Evaluation Board Schematic. 24 Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com 202081B • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • August 2, 2012 DATA SHEET AAT2822/2823/2824/2825 TFT-LCD DC/DC Converter with WLED Driver and VCOM Buffer VIN 10V C1 4.7μF R1 0Ω 10V C2 0.1μF 20 21 19 N/C N/C N/C 16 15 0.6V R2 14 13 R11 LX 200kΩ 12 LX C8 100pF D1 3 BAT54SDW A3 1 C20 0.22μF 50V 6 C21 0.22μF 50V C14 0.1μF 50V 5 4 3 BAT54SDW J1 FBP DRVP C26 R18 open A1 C10 3 4 C11 6 1 VAVDD VIN AVDD C16 0.22μF 25V J8 stage2 2 C17 0.22μF 50V BAT54SDW A4 3 J9 4 0.1μF 50V C28 R19 VIN 5 0.1μF 50V C27 VDD 0Ω C15 0.1μF 50V Adj 10pF R7 6.04kΩ 25V EN 0.1μF 25V 2 stage 3 stage4 C13 0.1μF 50V 0.6V R6 VIN stage3 1 2 J5 C12 0.1μF 25V 5 4 VAVDD C6 22 μF 25V 1 2 6 Adj R3 6.04kΩ C3 10μF 10V L1 2.2μH 5 6 1 C29 0.22μF J10 stage4 50V 1 2 1 2 stage 2 C18 0.22μF 25V C19 0.22μF 50V 1 2 COMP 17 C23 0.1μF 25V 2 1 1 2 11 DRVN PGND1 FB FBP WEN 7 J2 WEN J6 N/C 18 VDD A2 J4 22 23 FBN DRVN VIN N/C AAT2825 10 R9 Adj 6 0V REF EN VGL (negative) 5 N/C 9 4 R10 6.04kΩ C7 N/C PGND2 VDD 0.22μF 6.3V 3 FBN U1 N/C 8 1.2V VIN N/C 2 DRVP 1 AGND 24 AGND 0.1μF 50V VGH (positive) 2 BAT54SDW C30 0.22μF 50V Figure 9: AAT2825IBK Evaluation Board Schematic. Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com 202081B • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • August 2, 2012 25 DATA SHEET AAT2822/2823/2824/2825 TFT-LCD DC/DC Converter with WLED Driver and VCOM Buffer Figure 10: AAT28XXIBK Evaluation Board Top Side Layout. 26 Figure 11: AAT28XXIBK Evaluation Board Bottom Side Layout. Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com 202081B • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • August 2, 2012 DATA SHEET AAT2822/2823/2824/2825 TFT-LCD DC/DC Converter with WLED Driver and VCOM Buffer Ordering Information1,2 Package Part Marking1 Part Number (Tape and Reel)2 TQFN44-24 TQFN44-24 TQFN44-24 TQFN44-24 TQFN44-24 TQFN44-24 TQFN44-24 TQFN44-24 8XXYY F8XYY B7XYY F9XYY AAT2822IBK-T1 AAT2822IBK-1-T1 AAT2823IBK-T1 AAT2823IBK-1-T1 AAT2824IBK-T1 AAT2824IBK-1-T1 AAT2825IBK-T1 AAT2825IBK-1-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 Pin 1 Identification Chamfer 0.300 ×45° 0.255 ± 0.025 1 4.000 ± 0.050 2.700 ± 0.050 2.700 ± 0.050 Top View 0.000 −0.050 Bottom View 0.214 ± 0.036 0.750 ± 0.050 4.000 ± 0.050 Pin 1 Dot By Marking 0.500 BSC 0.400 ± 0.050 TQFN44-24 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. Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com 202081B • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • August 2, 2012 27 DATA SHEET AAT2822/2823/2824/2825 TFT-LCD DC/DC Converter with WLED Driver and VCOM Buffer 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. Skyworks assumes no liability for any materials, products or information provided hereunder, including the sale, distribution, reproduction or use of Skyworks products, information or materials, except as may be provided in Skyworks Terms and Conditions of Sale. THE MATERIALS, PRODUCTS AND INFORMATION ARE PROVIDED “AS IS” WITHOUT WARRANTY OF ANY KIND, WHETHER EXPRESS, IMPLIED, STATUTORY, OR OTHERWISE, INCLUDING FITNESS FOR A PARTICULAR PURPOSE OR USE, MERCHANTABILITY, PERFORMANCE, QUALITY OR NON-INFRINGEMENT OF ANY INTELLECTUAL PROPERTY RIGHT; ALL SUCH WARRANTIES ARE HEREBY EXPRESSLY DISCLAIMED. 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Additional information, including relevant terms and conditions, posted at www.skyworksinc.com, are incorporated by reference. 28 Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • [email protected] • www.skyworksinc.com 202081B • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • August 2, 2012