AAT2822 Datasheet PDF & Specifications

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AAT2822 SKYWORKS

Document overview

Manufacturer or author: Provided By digicamel.com
PDF pages: 28

Technical content

Features

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 Positive Output, VGH
Up to 13.2V Input Supply (VDD)
Adjustable Voltage up to 30V @ 20mA ▪ ±3% Typical Accuracy 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

TFT-LCD DC/DC Converter with WLED Driver and VCOM Buffer Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • sales@skyworksinc.com • www.skyworksinc.com 202081B • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • August 2, 2012 Typical Application VIN LX FB COMP DRVP FBP FBN DRVN REF VGL VAVDD RIN RFB1 RFB2CIN2 CAVDDOUT CDRVP CDRVN RCOMP RFBP1 CIN1 CVGH CCOMP CWIN CVGL C REF D2 D3 VDD VIN VGH VLED WLX OVP WEN WDIM WFB PWM ON OFF EN ON OFF RBAL Up to 13 strings OPIN OP- OUT OP+ AGND PGND1 PGND2 WCOMP RWCOMP CWCOMP VAVDD VCOM_IN VCOM_OUT ROP1 ROP2 CWOUT CCOMOUT VIN VDD L12.5V - 5.5V 2.5V - 5.5V RFBN1 RFBP2RFBN2 ROVP1 ROVP2

TFT-LCD DC/DC Converter with WLED Driver and VCOM Buffer Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • sales@skyworksinc.com • www.skyworksinc.com 202081B • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • August 2, 2012 1. Future products. Please contact factory for availability. Pin Descriptions Pinout is preliminary and subject to change during development. Pin Number Symbol Function DescriptionAAT2822 AAT2823 AAT28241 AAT28251 1 1 n/a n/a WLX O Boost inductor node. Connect an inductor between IN and WLX. WLX is high impedance in shutdown. 2 2 2 2 PGND2 I/O Power ground. Connect to GND underneath the IC. 3 3 3 3 REF O Internal reference bypass terminal. Connect a 0.1µF capaci- tor from this terminal to analog ground (GND). External load capability to 50µA. 4 4 4 4 FBN I Negative charge-pump regulator feedback input. Regulates to 0V nominal. 5 5 n/a n/a WEN I Active high logic level enable for WLED Driver. 6 6 6 6 DRVN O Negative charge-pump driver output. Output high level is VDD, and low level is PGND. 7 7 7 7 VDD PI Positive and negative charge-pump driver supply voltage. By- pass to PGND with a 0.1µF capacitor. 8 8 8 8 DRVP O Positive charge-pump driver output. Output high level is VINP, and low level is PGND. 9 9 9 9 EN I Active high logic level enable input. Connect EN to IN for normal operation. 10 10 10 10 FBP I Positive charge-pump regulator feedback input. Regulates to 0.6V nominal. Connect feedback resistive divider to analog ground (GND). 11 11 11 11 PGND1 I/O Power ground. Connect to GND underneath the IC. 12 12 12 12 LX O Main boost regulator power MOSFET N-channel drain. Connect output diode and output capacitor as close to PGND as possible. 13 13 13 13 COMP I Step-up regulator error-amplifier compensation point. Connect a series RC from COMP to AGND. 14 14 14 14 FB O Main boost regulator feedback input. Regulates to 0.6V nomi- nal. Connect feedback resistive divider to analog ground (GND) to set output voltage. 15 n/a 15 n/a OPIN I Operational-amplifier power input. Power supply rail for the operational amplifiers. Typically connected to VAVDD. Bypass OPIN to GND with a 0.1µF capacitor. 16 n/a 16 n/a OP+ I Operational-amplifier non-inverting input. 17 n/a 17 n/a OP- I Operational-amplifier inverting input. 18 n/a 18 n/a OUT O Operational-amplifier output. 19 19 n/a n/a WCOMP I White LED driver error-amplifier compensation point. Connect a series RC from WCOMP to AGND. 20 20 n/a n/a WFB O Feedback pin. Connect a resistor to ground to set the maximum LED current. 21 21 n/a n/a OVP O Feedback pin for over-voltage protection sense. Connect a re- sistive divider between the boost converter output and ground. capacitor between IN and GND, as close to the pins as possible. 23 23 AGND AGND AGND I/O Analog ground. Connect to power ground (PGND) underneath the IC. 24 24 n/a n/a WDIM I 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/a 15, 16, 17, 18 1, 19, 20, 1, 15, 16, 17, 18, 19, 20, 21 N/C Not connected. EP EP 5, 24, EP 5, 24, EP GND Ground. EP = Exposed paddle, connect to PCB ground plane.

TFT-LCD DC/DC Converter with WLED Driver and VCOM Buffer Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • sales@skyworksinc.com • www.skyworksinc.com 202081B • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • August 2, 2012 Pin Configurations TQFN44-24 (Top View) AAT2822 AAT2823 WLX PGND2 REF FBN WEN DRVN VDD DRVP EN FBP PGND1 LX OPIN OP+ FB COMP OP- OUT EP WCOMP WFB OVP VIN AGND WDIM WLX PGND2 REF FBN WEN DRVN VDD DRVP EN FBP PGND1 LX N/C N/C FB COMP N/C N/C EP WCOMP WFB OVP VIN AGND WDIM AAT2824 AAT2825 N/C PGND2 REF FBN GND DRVN VDD DRVP EN FBP PGND1 LX OPIN OP+ FB COMP OP- OUT EP N/C N/C N/C VIN AGND GND N/C PGND2 REF FBN GND DRVN VDD DRVP EN FBP PGND1 LX N/C N/C FB COMP N/C N/C EP N/C N/C N/C VIN AGND GND

TFT-LCD DC/DC Converter with WLED Driver and VCOM Buffer Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • sales@skyworksinc.com • www.skyworksinc.com 202081B • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • August 2, 2012 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. Part Number Descriptions Part Number LCD Bias Startup Sequence Backlight VCOM Buffer AAT2822  VAVDD->VGH->VGL   AAT2822-1  VAVDD->VGL->VGH   AAT2823  VAVDD->VGH->VGL  AAT2823-1  VAVDD->VGL->VGH  AAT2824  VAVDD->VGH->VGL  AAT2824-1  VAVDD->VGL->VGH  AAT2825  VAVDD->VGH->VGL AAT2825-1  VAVDD->VGL->VGH Absolute Maximum Ratings1 Description Value Units VIN, EN -0.3 to 7 V VDD, OPIN, OUT, OP+, OP- -0.3 to 15 LX, WLX -0.3 to 30 WCOMP, COMP, FB, FBP, FBN, REF, WEN, PWM, WFB, OVP -0.3 to VIN + 0.3 DRVP -0.3 to (VDD + 0.3) DRVN -0.3 to (VDD + 0.3) Thermal Information2 Symbol Description Value Units ΘJA Thermal Resistance3 50 °C/W PD Maximum Power Dissipation 2 W TJ Operating Junction Temperature Range -40 to 150 °CTLEAD Maximum Soldering Temperature (at Leads) 300

TFT-LCD DC/DC Converter with WLED Driver and VCOM Buffer Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • sales@skyworksinc.com • www.skyworksinc.com 202081B • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • August 2, 2012

Electrical Characteristics

VIN = 5V, EN = WEN = WDIM = V IN, VAVDD = VDD = 12V, TA = -40°C to 85°C unless otherwise noted. Typical values are at TA = 25°C. Symbol Description Conditions Min Typ Max Units Power Supply VIN Input Voltage Range 2.5 5.5 V VUVLO Under-Voltage Lockout Threshold Rising Edge 2.4 2.5 V UVLOHYS UVLO Hysteresis 50 mV IIN IN Quiescent Current VFB = VFBP = 0.7V, VFBN = -0.1, LX not switching 1.1 1.6 mA ISHDN Shutdown Current EN = WEN = Low, ISHDN = IIN + IDD, VDD = 5V 1 µA VREF REF Output Voltage No load 1.182 1.20 1.218 V REF Load Regulation 0 < ILOAD < 50µA 10 mV REF Current In regulation 50 µA TSD Thermal Shutdown Temperature rising +140 OCHysteresis 15 Main Step-Up Regulator VAVDD Output Voltage Range VIN - VDIODE 14.5 V FOSC Operating Frequency 910 1300 1690 kHz DCMAX Maximum Duty Cycle 86 90 % VFB FB Regulation Voltage No Load 0.588 0.6 0.612 V FB Fault Trip Level VFB falling 0.535 0.546 0.557 V FB Load Regulation 0 < IAVDD < full load 0.01 %/mA FB Line Regulation VIN = 2.5V to 5.5V 0.1 ±0.4 %/V FB Input Bias Current VFB = 0.7V -1 +1 µA RLX(ON) LX On-Resistance ILX = 200mA 350 700 mΩ ILX LX Leakage Current VLX = 13.2V 0.01 20 µA ILIM LX Current Limit VFB = 0.7V, duty cycle = 75% 1 A tSS Soft-Start Period 1.3 ms Gate High Charge Pump (VGH) VDD VDD Input Supply Range 2.7 13.2 V Operating Frequency FOSC kHz VFBP FBP Regulation Voltage 0.588 0.6 0.612 V FBP Fault Trip Level VFBP Falling 470 530 mV IFBP FBP Input Bias Current VFBP = 0.7V -1 +1 μA DRVPPRDS DRVP PCH ON-Resistance 3 6 Ω DRVPNRDS DRVP NCH On-Resistance VFBP = 0.585V 1.5 3 Ω VFBP = 0.615V 20 kΩ Gate Low Charge Pump (VGL) VDD VDD Input Supply Range 2.7 13.2 V Operating Frequency FOSC Hz VFBN FBN Regulation Voltage -50 0 +50 mV FBN Fault Trip Level VFBN Rising 408 425 442 mV IFBN FBN Input Bias Current VFBN = -0.1V -1 +1 μA DRVNPRDS DRVN PCH ON-Resistance 3 6 Ω DRVNNRDS DRVN NCH On-Resistance VFBN = 0.035V 1.5 3 Ω VFBN = -0.025V 20 kΩ

TFT-LCD DC/DC Converter with WLED Driver and VCOM Buffer Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • sales@skyworksinc.com • www.skyworksinc.com 202081B • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • August 2, 2012 VIN = 5V, EN = WEN = WDIM = V IN, VAVDD = VDD = 12V, TA = -40oC to 85oC unless otherwise noted. Typical values are at TA = 25oC. Symbol Description Conditions Min Typ Max Units WLED Driver (AAT2822, AAT2823 Only) VLED Output Voltage VIN - VDIODE 28 V IOUT Maximum Continuous Output Current VLED = 28V 50 mA ≥VFB/ ≥VIN Line Regulation VIN = 2.5V to 5.5V 0.7 %/V RDS(ON) Low Side Switch On-Resistance 300 mΩ VWFB WFB Pin Regulation 0.282 0.3 0.318 V TSS Soft-Start Time From Enable to Output Regulation; VFB = 300mV 300 µs VOVP Over-Voltage Protection Threshold VLED Rising 0.55 0.60 0.65 V OVHYS Over-Voltage Hysteresis VLED Falling 25 mV ILIMIT N-Channel Current Limit 1.3 A FPWM Maximum WDIM PWM Frequency 1 kHz DCMIN Minimum Duty Cycle 5 % VCOM Buffer (AAT2822 , AAT2824 Only) VOPIN Supply Range 4.5 13.2 V IOPIN Supply Current 1.5 2.5 mA VOS Input Offset Voltage (VNEG, VPOS, VOUT) ≡ VSUP/2 12 mV VCM Input Common-Mode Range 0 VSUP V VOH Output Voltage Swing, High IOUT = 5mA VSUP - 150 mV VOL Output Voltage Swing, Low IOUT = -5mA 150 mV ISC Short-Circuit Current VSUP/2 Source 75 mASink 75 GBW Gain Bandwidth Product 12 MHz SR Slew Rate 13 V/µs Logic WDIM/ WENL/ENL Enable Input Low Voltage VIN = 2.5V 0.4 V WDIM/ WENH/ENH Enable Input High Voltage VIN = 5.5V 1.4 V IEN WDIM/WEN/EN Input Current 1 µA

TFT-LCD DC/DC Converter with WLED Driver and VCOM Buffer Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • sales@skyworksinc.com • www.skyworksinc.com 202081B • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • August 2, 2012 Typical Characteristics Oscillator Frequency vs. Temperature Temperature (°C) Oscillator Frequency (mHz) -40- 15 10 35 60 85 1.235 1.240 1.245 1.250 1.255 1.260 1.265 1.270 1.275 1.280 1.285 Power Up Sequencing (VAVDD→VGH→VGL; V IN = 5.0V) Time (500µs/div) EN/SET (5V/div) V AVDD (5V/div) V GL (20V/div) V GH (20V/div) Power Up Sequencing (VAVDD->VGL->VGH; VIN = 5.0V) Time (1ms/div) EN/SET (2V/div) V AVDD (2V/div) VGL (10V/div) VGH (10V/div) Main Boost Efficiency (VOUT = 12V) Output Current (mA) Efficiency (%) 05 0 100 200150 300250 400350 500450 100 Main Boost Load Transient (VIN = 5.0V) Time (500µs/div) VOUT (100mV/div) IOUT (50mA/div) 100mA 10mA Line Regulation Input Voltage (V) Output Voltage (V) 11.75 11.80 11.85 11.90 11.95 12.00 12.05 12.10 12.15 12.20 12.25 IOUT = 1mA IOUT = 10mA IOUT = 100mA

TFT-LCD DC/DC Converter with WLED Driver and VCOM Buffer Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • sales@skyworksinc.com • www.skyworksinc.com 202081B • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • August 2, 2012 Typical Characteristics VGH vs. Temperature Temperature (°C) VGH (V) -40- 15 10 35 60 85 29.5 29.6 29.7 29.8 29.9 30.0 30.1 30.2 30.3 30.4 30.5 VGH Load Regulation Load Current (mA) Positive Output Voltage (V) 02 48 61 210 1614 2018 29.5 29.6 29.7 29.8 29.9 30.0 30.1 30.2 30.3 30.4 30.5 5.0V 2.7V VGL vs. Temperature Temperature (°C) VGL (V) -40- 15 10 35 60 85 -30.50 -30.40 -30.30 -30.20 -30.10 -30.00 -29.90 -29.80 -29.70 -29.60 -29.50 VGL Load Regulation Load Current (mA) Negative Output Voltage (V) 02 48 61 210 1614 2018 -30.5 -30.4 -30.3 -30.2 -30.1 -30.0 -29.9 -29.8 -29.7 -29.6 -29.5 5.0V 2.7V WLED Efficiency vs. Load Current (7S3P; VIN = 5V; VL = 12V) Load Current (mA) Efficiency (%) 01 02 04 030 6050 8070 10090 WLED Operation at 300mA Load (VIN = 5.0V, 3S13P) Time (200µs/div) VLED (5V/div) ILED (500mA/div) VOUT (100mV/div)

TFT-LCD DC/DC Converter with WLED Driver and VCOM Buffer Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • sales@skyworksinc.com • www.skyworksinc.com 202081B • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • August 2, 2012 Typical Characteristics VCOM Buffer Supply Current vs. Temperature (VIN = 5.0V, VOPIN = 12V) Temperature (°C) VGL (V) -40- 15 10 35 60 85 1.50 1.55 1.60 1.65 1.70 1.75 1.80 1.85 1.90 1.95 2.00 VCOM Input Offset Voltage vs. Temperature (VIN = 5.0V, VOPIN = 12V) Temperature (°C) Input Offset Voltage (mV) -40- 15 10 35 60 85 0.0 0.5 1.0 1.5 2.0 2.5

TFT-LCD DC/DC Converter with WLED Driver and VCOM Buffer Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • sales@skyworksinc.com • www.skyworksinc.com 202081B • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • August 2, 2012 Functional Block Diagram AAT2822 Step-up Controller Charge Pump Control Reference OP WLED Control VDD FBN REF VIN COMP LX FB DRVP FBP DRVN WFB OPIN OP- OUT OP+ Brightness Control OVP WLX WEN WDIM EN WCOMP AGND PGND1 PGND2 Functional Description Main Boost Converter 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. Dual Charge-Pump Regulator The AAT2822 provides low-power regulated output volt- ages from two individual charge pumps to provide the VGH and VGL supplies. Using a single stage, the VGL charge pump inverts the supply voltage (V DD) and pro - vides a regulated negative output voltage. The VGH charge pump doubles VDD and provides a regulated posi- tive 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 condi - tions. A constant switching frequency of 1.3MHz mini - mizes output ripple and capacitor size. White LED Backlight Applications 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

TFT-LCD DC/DC Converter with WLED Driver and VCOM Buffer Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • sales@skyworksinc.com • www.skyworksinc.com 202081B • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • August 2, 2012 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 dim- ming 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 WLED Boost Stop Switching VWLED >V OVP No Yes Yes No Figure 1: WLED Driver Operation. 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 sequenc- ing 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 (V AVDD) first, followed by the gate voltages VGL then VGH. The sequence for the plain option is to establish V AVDD first followed by VGH then VGL. The WLED backlight driver is independently controlled by WEN and WDIM. Operating Faults The AAT2822 family continuously monitors for fault con- ditions 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.

TFT-LCD DC/DC Converter with WLED Driver and VCOM Buffer Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • sales@skyworksinc.com • www.skyworksinc.com 202081B • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • August 2, 2012 Start EN High MAIN BOOST VFB > FB Fault Trip Level and Persist NEGATIVE CP VFBN >FBN Fault Trip Level and Persist POSITIVE CP VFBP >FBP Fault Trip Level and Persist Start-Up Sequence Complete Shut-Down Main Boost, Negative CP, and Positive CP Yes No Yes Yes Yes No No No No EN Low OPAMP Figure 2: Startup Sequence for AAT282X-1 1. 1. For AAT282x the startup sequence is positive charge pump followed by the nega- tive charge pump.

Application Information

The high output ripple inherent in the boost converter necessitates low impedance output filtering. Multi-layer ceramic (MLC) capacitors provide small size and ade - quate capacitance, low parasitic equivalent series resis - tance (ESR) and equivalent series inductance (ESL), and are well suited for use with the primary step-up con - verter. MLCs 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 during the power switch ON interval, when the output diode is not con - ducting. And because the VGH, VGL also have their input power from the main step-up converter output, the out- put capacitor may also decrease the inrush current dur - ing 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 rec - ommended. 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 measure - ments should confirm that output voltage droop is acceptable. Input Capacitor 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 capaci - tors may be necessary to meet stringent output ripple and transient load requirements. These can replace (or be used in parallel with) ceramic capacitors. Both tanta- lum and OSCON-type capacitors are suitable due to their low ESR and excellent temperature stability (although they exhibit much higher ESR than MLCs). Aluminum- electrolytic types are less suitable due to their high ESR

TFT-LCD DC/DC Converter with WLED Driver and VCOM Buffer Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • sales@skyworksinc.com • www.skyworksinc.com 202081B • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • August 2, 2012 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 recov - ery, 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 operat- ing junction temperature under full load operating condi- tions. Forward voltage (V F) and package thermal resis - tance (θJA) are the dominant factors to consider in select- ing 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 cur - rent: 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 θ JA 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 con- sidered 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 neces- sary, the peak inductor current can exceed the satura - tion 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 - verter. Maximum duty cycle (D MAX) 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 condi - tions. Peak current may be calculated from the following equation, again assuming continuous conduction mode. Worst-case peak current occurs at minimum input volt - age (maximum duty cycle) and maximum load. Switching frequency (Fs) is at 1.3MHz with a 2.2µH inductor. IPEAK = + IOUT 1 - DMAX DMAX · VIN(MIN) 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. IPEAK IRMS = 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 = IRMS 2 · DCR Setting the Output Voltage The resistive divider network R2 and R3 of Figure 7 pro- grams 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 -

TFT-LCD DC/DC Converter with WLED Driver and VCOM Buffer Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • sales@skyworksinc.com • www.skyworksinc.com 202081B • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • August 2, 2012 gested value for R3 is 6.04kΩ. The resistive divider can be calculated in the following equation: VAVDD VFB VAVDD 0.6V VAVDD (V) R3 = 6.04kΩ R2 (kΩ) R3 = 59kΩ R2 (MΩ) 9 84.5 0.825 10 93.1 0.931 11 105 1.02 12 115 1.13 13 124 1.21 15 143 1.4 20 196 1.1 22 215 2.1 24 237 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) sys - tem 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: fZ_ESR = 1 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: fZ_RHP = VIN 2π · L1 · IAVDD · VAVDD It is recommended to design the bandwidth to one decade lower than the frequency of RHP zero to guaran- tee 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 stag - es 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: VGH - VAVDD(MIN) VAVDD(MIN) - 2VF nP = for the positive output and VGL 2VF - VAVDD(MIN) nN = 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 (V ON) to the FBN and REF pins. The maximum reference voltage current is 200µA; therefore, the minimum allowable value for R10 of Figure

TFT-LCD DC/DC Converter with WLED Driver and VCOM Buffer Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • sales@skyworksinc.com • www.skyworksinc.com 202081B • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • August 2, 2012 6 is 6.04kΩ. It is best to select the smallest value pos - sible for R10, as this will keep the value of R 9 to a mini - mum. With R10 selected, R9 can be determined: R9 = · R10 = · R10 VGL VREF VGL 1.2V Positive Output Voltage (VGH) The positive output voltage is set by a resistive divider from the output (V GH) 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 R 6: R6 = R7 · - 1 = R7 · - 1 VGH VFBP VGH 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 reser- voir 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. 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 fre - quency content of the input current localized, minimizing radiated and conducted EMI. Rectifier Diodes For the rectifiers, use Schottky diodes with a voltage rat- ing of 1.5 times the input voltage. The maximum steady- state voltage seen by the rectifier diodes for both the 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-volt - age threshold occurs prior to the output reaching VLED+(MAX). The value of R 5 should be selected from 10kΩ to 20kΩ to minimize losses without degrading noise immunity. R 4 = R5 · -1 = 10kΩ · -1 VLED+(MAX) VOVP VLED+(MAX) 0.6V WLX OVPWFB C4C5 0.6V0.3V VIN VWLXVLED 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 for- ward voltage characteristics (V FLED), quantity of series connected LEDs (N), and the feedback pin voltage (VFB). VOUT = VFB + N · VFLED

TFT-LCD DC/DC Converter with WLED Driver and VCOM Buffer Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • sales@skyworksinc.com • www.skyworksinc.com 202081B • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • August 2, 2012 When the rising OVP threshold is exceeded, switching is stopped and the output voltage decays. Switching auto- matically 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 (mul - tiplied by the resistor divider scaling factor). High oper - ating 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 program- ming error (ΔILED) is proportional to voltage error across an individual LED (ΔVFLED). ∆VFLED = N · VFLED(TYP) - VOVP(MIN) - VWFB N To minimize the ΔI LED error, the minimum OVP voltage (VOVP(MIN)) may be increased, yielding a corresponding increase in the maximum OVP voltage (V OVP(MAX)). Measurements should confirm that the maximum switch- ing node voltage (VWLX(MAX)) is less than 30V under worst case operating conditions. VWLX(MAX) = VOVP(MAX) · + 1 + VF + VRING 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 (R 8). For maximum accuracy, a 1% tolerance resistor is recommended. The ballast resistor (R 8) value can be calculated as fol - lows: 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 cor - responds to a minimum resistor value of 1.15 Ω R8 = = 1.15Ω0.3V 260mA Maximum ILED Current (mA) R8(Ω) 30 0.768 25 0.909 20 1.15 15 1.54 10 2.32 5 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 (V LED), minus the maximum feedback voltage (V WFB(MAX)) divided by the maximum LED forward voltage (V FLED(MAX)) which can be estimated from the manufacturers’ datasheet at the maximum LED operating current. VLED = VOVP(TYP) · + 1R5 N = VOVP(MIN) - VWFB(MAX) VFLED(MAX) For example, the typical forward voltage of the white LED is 3.5V at 20mA. VLED = VOVP(TYP) · = 0.6V · = 27.8V+ 1R 5 R 4 + 1464kΩ 10kΩ N = = = 7.8 LEDs VOVP(MIN) - VWFB(MAX) VFLED(MAX) 27.8V - 0.6V 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 proportion- ally 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.

TFT-LCD DC/DC Converter with WLED Driver and VCOM Buffer Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • sales@skyworksinc.com • www.skyworksinc.com 202081B • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • August 2, 2012 Choose R21 = 4.99kΩ and VC25 = 2V, and solve for R22: R 21 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 fre- quency 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 recov- ery, high-voltage Schottky diodes are considered the best choice for the WLED boost converter. The output diode is sized to maintain acceptable efficiency and rea- sonable operating junction temperature under full load operating conditions. Forward voltage (V F) and package thermal resistance (θJA) are the dominant factors to con- sider in selecting a diode. The diode's non-repetitive peak forward surge current rating (I FSM) should be con - sidered for high pulsed load applications such as camera flash. The I FSM 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 com - parative measure between similarly rated devices. 40V rated Schottky diodes are recommended for outputs less than 30V, while 60V rated Schottky diodes are rec - ommended for outputs greater than 35V. The average diode current is equal to the output cur - rent: 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 θ JA can be mini - mized 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 con- sidered 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 con - ditions. Peak current may be calculated from the follow- ing 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 1 - DMAX DMAX · VIN(MIN) 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 recom- mended 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 out- put. 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.

TFT-LCD DC/DC Converter with WLED Driver and VCOM Buffer Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • sales@skyworksinc.com • www.skyworksinc.com 202081B • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • August 2, 2012 The output capacitor size can be estimated using the equation: IOUT · DMAX FS · ∆VOUT COUT = To maintain stable operation at full load, the output capacitor should be sized to maintain ΔVOUT b etween 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. 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 exter- nal supply to prevent damage to the device; the jumper J7 should be left open to disconnect VAVDD from VOPIN.

TFT-LCD DC/DC Converter with WLED Driver and VCOM Buffer Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • sales@skyworksinc.com • www.skyworksinc.com 202081B • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • August 2, 2012 100pF 200kΩ R11 4.7μF 10VC 1 VIN WDIM 24 WLX1 WCOMP 19 EN9 AGND 23 PGND22 WEN5 FBP10 OVP 21 DRVP8 VDD7 WFB 20 OP+ 16 OPIN 15 PGND111 LX12 COMP 13 FB 14 OP- 17 OUT 18 VIN 22 REF3 FBN4 DRVN6 AAT2822 10μF 10V 0.22μF 6.3V 0.1μF 25V C12 0.22μF 50V C21 PWM 2.2μH Adj 6.04kΩ 22μF 25V 8nF 2.2μF 50V adj 10kΩ 6.04kΩ R10 Adj 6.04kΩ 10kΩ R14 10kΩ R13 17.4kΩ R12 adj 0.1μF 50V C13 0.22μF 25V C18 0.1μF 50V C11 0.1μF 25V C10 0.22μF 25V C16 0.22μF 50V C19 0.22μF 50V C17 VIN EN LX VAVDD VGH (positive) VGL (negative) VIN WEN Adj 0.1μF 10VC 2 WLX 10μF 16V 2.2μH OVP OVP R15 AGND VDD 3 4 BAT54SDW VDD open R16 BAT54SDW 0.1μF 50V C14 0.1μF 50V C15 BAT54SDW 0.22μF 50V C20 2 stage 3 J51 2 stage4 0.1μF C22 DRVN DRVP FBP FBN 0.1μF 25V C23 100Ω R17 10nF C24 2 stage 2 VIN VIN-WLED open R19 R18 VAVDD R21 VIN R20 HF-PWM open R23 open R22WFB open C25 3 4 BAT54SDW 0.1μF 50V C27 0.1μF 50V C28 stage2 J81 stage3J91 stage4J100.22μF 50V C29 0.22μF 50V C30 AVDD VIN VOPIN 10pF 25V C26 WLED+ WLED- 1.2V 0.6V 0.6V 0.6V Figure 6: AAT2822IBK Evaluation Board Schematic.

TFT-LCD DC/DC Converter with WLED Driver and VCOM Buffer Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • sales@skyworksinc.com • www.skyworksinc.com 202081B • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • August 2, 2012 Component Part Number Description Manufacturer U1 AAT2822IBK TFT-LCD DC-DC Converter with WLED Driver and VCOM Buffer Skyworks C1 GRM188R61A475K CAP CERAMIC 4.7μF 0603 X5R 10V 10% Murata C2 GRM188R71C104K CAP CERAMIC 0.1μF 0603 X7R 16V 10% C3, C4 GRM21BR61C106K CAP CERAMIC 10μF 0805 X5R 16V 10% C5 GRM31CR71H225K CAP CERAMIC 2.2μF 1206 X7R 50V 10% C6 GRM31CR61C226M CAP CERAMIC 22μF 1206 X5R 16V 20% C7 GRM188R71A224K CAP CERAMIC 0.22μF 0603 X7R 10V10% C8 GRM1885C1H101J CAP CERAMIC 100pF 0603 COG 50V 5% C9 GRM2195C1H822J CAP CERAMIC 8nF 0805 X7R 50V 10% C10, C12, C22, C23 GRM188R61E104K CAP CERAMIC 0.1μF 0603 X5R 25V 10% C11, C13, C14, C15, C27, C28 GRM188R71H104K CAP CERAMIC 0.1μF 0603 X7R 50V 10% C16, C18 GRM188R61E224K CAP CERAMIC 0.22μF 0603 X5R 25V10% C17, C19, C20, C21, C29, C30 GRM21BR71H224K CAP CERAMIC 0.22μF 0805 X7R 50V10% C24 GRM188R71H103K CAP CERAMIC 10nF 0603 X7R 50V 10% C25 NC C26 GRM1885C1H100J CAP CERAMIC 10pF 0603 COG 50V 5% A1, A2, A3, A4 BAT54SDW-7-F Schottky Diode Array 30V SC70-6 Diode Inc D1, D2 SS16L Schottky Diode 1A 60V Micro SMP Taiwan Semiconductor L1, L2 CDRH5D16-2R2 POWER INDUCTOR 2.2μH 3.0A SMD Sumida R2, R4, R6, R8, R9 Adjustable Value (See Equations.1 – 5 and Table 5); 0603 Yageo R3, R7, R10 RC0603FR-0760K4L Res 6.04kΩ 1/10W 1% 0603 SMD R5, R13, R14 RC0603FR-0710KL Res 10kΩ 1/10W 1% 0603 SMD R11 RC0603FR-07200KL Res 200kΩ 1/10W 1% 0603 SMD R12 RC0603FR-0717K4L Res 17.4kΩ 1/10W 1% 0603 SMD R15, R19, R20, R21 RC0603FR-070RL Res 0Ω 1/10W 1% 0603 SMD R17 RC0603FR-07100RL Res 100Ω 1/10W 1% 0603 SMD R18, R22, R23, R25 NC Table 3: AAT2822IBK Evaluation Board Bill Of Materials (BOM). Panel Sizes (inches) WLED Matrix (Series and Parallel) Ballast Resistor R8 (Ω) 5 3S5P 2.37 5.6 3S6P 2.0 7 3S9P 1.3 8 3S10P/11P 1.2 10 3S13P 1.0 5 7S2P 4.7 Table 4: Ballast Resistor Selection for Different Panel Sizes. Eq. 1: R 2 = R3 · -1 = 6.04kΩ · -1 VAVDD VFB VAVDD 0.6V Eq. 2: R 9 = · R10 = · 6.04kΩ VGL VFBN VGL 1.2V Eq. 3: R 6 = R7 · - 1 = 6.04kΩ · - 1 VGH VFBP VGH 0.6V

TFT-LCD DC/DC Converter with WLED Driver and VCOM Buffer Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • sales@skyworksinc.com • www.skyworksinc.com 202081B • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • August 2, 2012 Eq. 4: R 4 = R5 · -1 = 10kΩ · -1 VLED+(MAX) VOVP VLED+(MAX) 0.6V Eq. 5: R8 = = VWFB(MAX) ILED(MAX) 0.3V ILED(MAX) 100pF 200kΩ R11 4.7μF 10V C1 VIN WDIM 24 WLX1 WCOMP 19 EN9 AGND 23 PGND22 WEN5 FBP10 OVP 21 DRVP8 VDD7 WFB 20 N/C 16 N/C 15 PGND111 LX12 COMP 13 FB 14 N/C 17 N/C 18 VIN 22 REF3 FBN4 DRVN6 AAT2823 10μF 10V 0.22μF 6.3V 0.1μF 25V C12 0.22μF 50V C21 PWM 2.2μH Adj 6.04kΩ 22μF 25V 8nF 2.2μF 50V adj 10kΩ 6.04kΩ R10 Adj 6.04kΩ 17.4kΩ R12 adj 0.1μF 50V C13 0.22μF 25V C18 0.1μF 50V C11 0.1μF 25V C10 0.22μF 25V C16 0.22μF 50V C19 0.22μF 50V C17 VIN EN LX VAVDD VGH (positive) VGL (negative) VIN WEN Adj 0.1μF 10V C2 WLX 10μF 16V 2.2μH OVP OVP AGND VDD 3 4 BAT54SDW VDD BAT54SDW 0.1μF 50V C14 0.1μF 50V C15 BAT54SDW 0.22μF 50V C20 2 stage 3 J51 2 stage4 DRVN DRVP FBP FBN 0.1μF 25V C23 2 stage 2 VIN VIN-WLED open R19 R18 VAVDD R21 VIN R20 HF-PWM open R23 open R22WFB open C25 3 4 BAT54SDW 0.1μF 50V C27 0.1μF 50V C28 stage2 J81 stage3J91 stage4J100.22μF 50V C29 0.22μF 50V C30 AVDD VIN 10pF 25V C26 WLED+ WLED- 1.2V 0.6V 0.6V 0.6V Figure 7: AAT2823IBK Evaluation Board Schematic.

TFT-LCD DC/DC Converter with WLED Driver and VCOM Buffer Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • sales@skyworksinc.com • www.skyworksinc.com 202081B • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • August 2, 2012 100pF 200kΩ R11 4.7μF 10VC 1 VIN N/C 24 N/C1 N/C 19 EN9 AGND 23 PGND22 WEN5 FBP10 N/C 21 DRVP8 VDD7 N/C 20 OP+ 16 OPIN 15 PGND111 LX12 COMP 13 FB 14 OP- 17 OUT 18 VIN 22 REF3 FBN4 DRVN6 AAT2824 10μF 10V 0.22μF 6.3V 0.1μF 25V C12 0.22μF 50V C21 Adj 6.04kΩ 22μF 25V 6.04kΩ R10 Adj 6.04kΩ 10kΩ R14 10kΩ R13 0.1μF 50V C13 0.22μF 25V C18 0.1μF 50V C11 0.1μF 25V C10 0.22μF 25V C16 0.22μF 50V C19 0.22μF 50V C17 VIN EN LX VAVDD VGH (positive) VGL (negative) VIN WEN Adj 0.1μF 10VC 2 2.2μH R15 AGND VDD 3 4 BAT54SDW VDD open R16 BAT54SDW 0.1μF 50V C14 0.1μF 50V C15 BAT54SDW 0.22μF 50V C20 2 stage 3 J51 2 stage4 0.1μF C22 DRVN DRVP FBP FBN 0.1μF 25V C23 100Ω R17 10nF C24 2 stage 2 VIN open R19 R18 VAVDD 3 4 BAT54SDW 0.1μF 50V C27 0.1μF 50V C28 stage2 J81 stage3J91 stage4J100.22μF 50V C29 0.22μF 50V C30 AVDD VIN VOPIN 10pF 25V C26 1.2V 0.6V 0.6V Figure 8: AAT2824IBK Evaluation Board Schematic.

TFT-LCD DC/DC Converter with WLED Driver and VCOM Buffer Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • sales@skyworksinc.com • www.skyworksinc.com 202081B • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • August 2, 2012 100pF 200kΩ R11 4.7μF 10VC 1 VIN N/C 24 N/C1 N/C 19 EN9 AGND 23 PGND22 WEN5 FBP10 N/C 21 DRVP8 VDD7 N/C 20 N/C 16 N/C 15 PGND111 LX12 COMP 13 FB 14 N/C 17 N/C 18 VIN 22 REF3 FBN4 DRVN6 AAT2825 10μF 10V 0.22μF 6.3V 0.1μF 25V C12 0.22μF 50V C21 Adj 6.04kΩ 22μF 25V 6.04kΩ R10 Adj 6.04kΩ 0.1μF 50V C13 0.22μF 25V C18 0.1μF 50V C11 0.1μF 25V C10 0.22μF 25V C16 0.22μF 50V C19 0.22μF 50V C17 VIN EN LX VAVDD VGH (positive) VGL (negative) VIN WEN Adj 0.1μF 10VC 2 2.2μH AGND VDD 3 4 BAT54SDW VDD BAT54SDW 0.1μF 50V C14 0.1μF 50V C15 BAT54SDW 0.22μF 50V C20 2 stage 3 J51 2 stage4 DRVN DRVP FBP FBN 0.1μF 25V C23 2 stage 2 VIN open R19 R18 VAVDD 3 4 BAT54SDW 0.1μF 50V C27 0.1μF 50V C28 stage2 J81 stage3J91 stage4J100.22μF 50V C29 0.22μF 50V C30 AVDD VIN 10pF 25V C26 1.2V 0.6V 0.6V Figure 9: AAT2825IBK Evaluation Board Schematic.

TFT-LCD DC/DC Converter with WLED Driver and VCOM Buffer Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • sales@skyworksinc.com • www.skyworksinc.com 202081B • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • August 2, 2012 Figure 10: AAT28XXIBK Evaluation Board Figure 11: AAT28XXIBK Evaluation Board Top Side Layout. Bottom Side Layout.

TFT-LCD DC/DC Converter with WLED Driver and VCOM Buffer Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • sales@skyworksinc.com • www.skyworksinc.com 202081B • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • August 2, 2012 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. Ordering Information1,2 Package Part Marking1 Part Number (Tape and Reel)2 TQFN44-24 8XXYY AAT2822IBK-T1 TQFN44-24 F8XYY AAT2822IBK-1-T1 TQFN44-24 B7XYY AAT2823IBK-T1 TQFN44-24 F9XYY AAT2823IBK-1-T1 TQFN44-24 AAT2824IBK-T1 TQFN44-24 AAT2824IBK-1-T1 TQFN44-24 AAT2825IBK-T1 TQFN44-24 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 TQFN44-24 4.000 ± 0.050 2.700 ± 0.050 Pin 1 Dot By Marking 4.000 ± 0.050 2.700 ± 0.050 0.214 ± 0.036 0.500 BSC 0.400 ± 0.050 0.750 ± 0.050 0.255 ± 0.025 Pin 1 Identification Chamfer 0.300 × 45 ° T op V iew Bottom V iew Side V iew 0.000 − 0.050 All dimensions in millimeters.

TFT-LCD DC/DC Converter with WLED Driver and VCOM Buffer Skyworks Solutions, Inc. • Phone [781] 376-3000 • Fax [781] 376-3100 • sales@skyworksinc.com • www.skyworksinc.com 202081B • Skyworks Proprietary Information • Products and Product Information are Subject to Change Without Notice. • August 2, 2012 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. Sky - works 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 here- under, 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. SKYWORKS DOES NOT WARRANT THE ACCURACY OR COMPLETENESS OF THE INFORMATION, TEXT, GRAPHICS OR OTHER ITEMS CONTAINED WITHIN THESE MATERIALS. SKYWORKS SHALL NOT BE LIABLE FOR ANY DAMAGES, IN - CLUDING BUT NOT LIMITED TO ANY SPECIAL, INDIRECT, INCIDENTAL, STATUTORY, OR CONSEQUENTIAL DAMAGES, INCLUDING WITHOUT LIMITATION, LOST REVENUES OR LOST PROFITS THAT MAY RESULT FROM THE USE OF THE MATERIALS OR INFORMATION, WHETHER OR NOT THE RECIPIENT OF MATERIALS HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. Skyworks products are not intended for use in medical, lifesaving or life-sustaining applications, or other equipment in which the failure of the Skyworks products could lead to personal injury, death, physical or en- vironmental damage. Skyworks customers using or selling Skyworks products for use in such applications do so at their own risk and agree to fully indemnify Skyworks for any damages resulting from such improper use or sale. Customers are responsible for their products and applications using Skyworks products, which may deviate from published specifications as a result of design defects, errors, or operation of products outside of pub- lished parameters or design specifications. Customers should include design and operating safeguards to minimize these and other risks. Skyworks assumes no liability for applications assistance, customer product design, or damage to any equipment resulting from the use of Skyworks products outside of stated published specifications or parameters. Skyworks, the Skyworks symbol, and “Breakthrough Simplicity” are trademarks or registered trademarks of Skyworks Solutions, Inc., in the United States and other countries. Third-party brands and names are for identification purposes only, and are the property of their respective owners. Additional information, including relevant terms and conditions, posted at www.skyworksinc.com, are incorporated by reference.

Selected Specification

Skyworks Solutions Inc. AAT2822 overview.

Overview

AAT2822 is listed in the Logic IC category. Available datasheets include documents from Skyworks Solutions Inc.. DigiCamel provides a local PDF and searchable HTML technical text for online reference.

Summary

TFT-LCD DC/DC Converter with WLED Driver and VCOM Buffer August 2, 2012

Description

TFT-LCD DC/DC Converter with WLED Driver and VCOM Buffer August 2, 2012

Source title AAT2822 Datasheet(PDF) - Skyworks Solutions Inc.

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