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A8440 AiT Semiconductor Inc. www.ait-ic.com 4CHANNEL WHITE LED DRIVER 1x /1.5x CHARGE PUMP DISPLAY BACKLIGHT SOLUTION DESCRIPTION FEATURES The A8440 is a complete backlight display solution that is designed to independently control LEDs. The A8440 is a charge pump WLED driver capable of driving up to 4 LEDs with 30mA each LED. Its four tightly regulated current sources ensure excellent LED current and brightness matching. LED driver current is programmed by an external resistor. The A8440 operates over an input voltage range from 3V to 5.5V, optimized for WLED applications powered by Li-Ion battery, requiring only for low cost ceramic capacitors. The A8440 provides excellent efficiency by operating the charge pump in a gain of 1 or 1.5. Maximum efficiency is achieved over Li-Ion battery voltage range by selecting the proper gain based on the LED forward voltage requirements. The A8440 has a fixed 1MHz switching frequency, consuming less than 1uA of supply current when shutdown. The A8440 LED dimming can be accomplished by several methods including using a DC voltage to set the RSET pin current, applying a PW signal on the control signals, or adding a switched resistor in parallel with RSET. The enable input pin allows the A8440 to be placed in power-down mode. The A8440 is available in 16pin TQFN (3x3mm) (4x4mm) package. QFN16 Typical Application Individually Current Regulation for Up to 4 LEDs with a Typical Tolerance of 5% Input Voltage Range: 3V to 5.5V Wide Current Range, up to 30mA per LED 3-bit Digital Output Control 3%Typical Tolerance Current Matching 1x and 1.5x mode Operating with Automatic Switchover High Available Total LED Current 120mA (4 x 30mA) Peak Efficiency Over 91% Fixed Frequency 1MHz Power-Saving Shutdown mode of 1uA Open LED Protection Soft-Start Over-Current-Protection and Current Limiting Available in TQFN-16 (3x3mm) and QFN16 (4x4mm) Package APPLICATION Portable Devices, Mobile Phone, DVR, Smart Phone...etc. Hand-held Devices, PDA, PMP, MP3, DSC...etc. White LED Backlight Application LED Modules ORDERING INFORMATION Package Type Part Number TQFN16(3x3mm) TQ16 QFN16 (4x4mm) Q16 A8440TQ16R A8440TQ16VR A8440Q16R A8440Q16VR R: Tape & Reel Note V: Green Package AiT provides all Pb free products Suffix “ V “ means Green Package REV1.2 - JAN 2007 RELEASED – JUN 2008 REVISED - -1- A8440 AiT Semiconductor Inc. www.ait-ic.com 4CHANNEL WHITE LED DRIVER 1x /1.5x CHARGE PUMP DISPLAY BACKLIGHT SOLUTION PIN DESCRIPTION Top View Top View Pin # Pin Name 1 EN 2 CTR0 Digital Control Input 0 3 CTR1 Digital Control Input 1 4 CTR2 Digital Control Input 2 5 RSET Set LED Output Current by the Current Sourced out of the RSET pin 6 VOUT Output Pin, Charge Pump output connected to the LED anodes 7 VIN Input Pin, Supply Voltage 8 C1+ Bucket Capacitor 1 Terminal 9 C1- Bucket Capacitor 1 Terminal 10 C2- Bucket Capacitor 2 Terminal 11 C2+ Bucket Capacitor 2 Terminal 12 GND Ground Pin 13 LED4 LED4 Cathode Terminal 14 LED3 LED3 Cathode Terminal 15 LED2 LED2 Cathode Terminal 16 LED1 LED1 Cathode Terminal REV1.2 Function Enable Input Active High - JAN 2007 RELEASED – JUN 2008 REVISED - -2- A8440 AiT Semiconductor Inc. www.ait-ic.com 4CHANNEL WHITE LED DRIVER 1x /1.5x CHARGE PUMP DISPLAY BACKLIGHT SOLUTION ABSOLUTE MAXIMUM RATINGS VIN, LEDx, VOUT Voltage -0.3V ~ 7.0V EN, CTRx Voltage -0.3V ~ VIN (V) RSET Voltage -0.3V ~ VIN (V) RSET Current ±1mA Storage Temperature Range Lead Temperature (Soldering, 10s) Operating Temperature Range -65oC ~ +150oC +300oC -40oC ~ +85oC ESD Ratings Human Body Model (HBM) Machine Model (MM) (Note1) ILED per LED pin Thermal Resistance (Junction to Ambient) (θJA) Power Dissipation (PD=@TA=25oC) 2kV 200V 0 to 30uA 68oC/W 1.47W Stresses above may cause permanent damage to the device. These are stress ratings only and functional operation of the device at these or any other conditions beyond those indicated in the Electrical Characteristics are not implied. Exposure to absolute maximum rating conditions for extended periods may affect device reliability . Note1: Machine models are with 200pF capacitor discharged directly into each pin. REV1.2 - JAN 2007 RELEASED – JUN 2008 REVISED - -3- A8440 AiT Semiconductor Inc. www.ait-ic.com 4CHANNEL WHITE LED DRIVER 1x /1.5x CHARGE PUMP DISPLAY BACKLIGHT SOLUTION ELECTRICAL CHARACTERISTICS VIN=3.5V, TA=25oC, IRSET=5uA, unless otherwise specified. Parameter VIN at mode Transition Symbol VIN-Transition from 1x to 1.5x RSET Regulated Voltage Programmed LED Current ILED ILED-ACC LED Channel Matching ILED-DEV Output Resistance (Open Loop) Charge Pump Frequency 1x to 1.5x Mode Iq ROUT Min Typ ILED=15mA 3.45 ILED=20mA 3.60 VRSET LED Current Accuracy Quiescent Current Conditions 1.19 1.23 Max Unit V 1.24 V ISET = 6uA 2.5 mA ISET=41uA 15.0 mA ISET=83uA 30.0 mA 0.6 % (ILED - ILEDAVG) / ILEDAVG 3 % VEN=0V Shutdown Mode 0.05 1 uA 1x Mode, No Load 0.5 1 mA 1.5x Mode, No Load 2.5 5 mA 1x Mode, IOUT=100mA 1.7 Ω 1.5x Mode, IOUT=100mA 4.3 Ω 1.0 MHz fOSC TDROPOUT 0.4 0.6 0.9 ms 0.001 1 uA Transition Dropout Delay Input Leakage Current IEN-CTR ON Inputs EN, CTR0, 1&2 Detect Threshold VEN-CTR On Inputs EN, High CTR0, 1 & 2 Low Input Current Limit ISC VOUT=GND Maximum Input Current ILIM VOUT>1V REV1.2 - JAN 2007 RELEASED – JUN 2008 REVISED - 0.8 V 0.7 V 30 45 60 mA 200 400 600 mA -4- A8440 AiT Semiconductor Inc. www.ait-ic.com 4CHANNEL WHITE LED DRIVER 1x /1.5x CHARGE PUMP DISPLAY BACKLIGHT SOLUTION TYPICAL PERFORMANCE CHARACTERISTICS VIN=3.6V, EN=VIN, TA=25oC, RSET=24KΩ, CIN=COUT=1uF, unless otherwise specified. 1. Input Current vs. PWM Duty Cycle 4LEDs @60mA, 100Hz PWM Duty Cycle LEDs @60mA, 1KHz PWM Duty Cycle 2. LED Current vs. Input Voltage 3. Supply Current vs. Input Voltage 4LEDs @60mA 4. LED Cathode Voltage vs. Input Voltage 1LED @15mA 5. Output Voltage vs. Input Voltage 1LED @15mA REV1.2 - JAN 2007 RELEASED – JUN 2008 REVISED - -5- A8440 AiT Semiconductor Inc. www.ait-ic.com 6. Efficiency vs. Line Voltage 4LEDs @60mA 4CHANNEL WHITE LED DRIVER 1x /1.5x CHARGE PUMP DISPLAY BACKLIGHT SOLUTION 4LEDs @80mA 7. Efficiency vs. Total LED Current (4LEDs) 8. Efficiency vs. Input Voltage 4LEDs 9. Efficiency vs. Line Voltage 4LEDs @15mA 10. Efficiency vs. Line Voltage 4LEDs @20mA REV1.2 - JAN 2007 RELEASED – JUN 2008 REVISED - -6- A8440 AiT Semiconductor Inc. www.ait-ic.com 4CHANNEL WHITE LED DRIVER 1x /1.5x CHARGE PUMP DISPLAY BACKLIGHT SOLUTION 11. Switching Waveform in 1x Mode VIN=4.2V, 4LEDs @80mA 12. Switching Waveform in 1.5x Mode VIN=3.2V, 4LEDs @80mA 13. 1KHz PWM Signal, Vcc=4.2V, 4ILED=60mA Positive Duty Cycle=30% PWM Control Enable (CTR0=0, CTR1=1, CTR2=1) CH1: PWM (DC Decoupling) CH2: VOUT (DC Decoupling) CH3: IOUT (AC Decoupling) 14. 1KHz PWM Signal, Vcc=3.2V, 4ILED=60mA Positive Duty Cycle=30% PWM Control Enable (CTR0=0, CTR1=1, CTR2=1) CH1: PWM (DC Decoupling) CH2: VOUT (DC Decoupling) CH3: IOUT (AC Decoupling) 15. 100Hz PWM Signal, Vcc=4.2V, 4ILED=60mA Positive Duty Cycle=40% PWM Control Enable (CTR0=0, CTR1=1, CTR2=1) CH1: PWM (DC Decoupling) CH2: VOUT (DC Decoupling) CH3: IOUT (AC Decoupling) 16. 100Hz PWM Signal, Vcc=3.2V, 4ILED=60mA Positive Duty Cycle=30% PWM Control Enable (CTR0=0, CTR1=1, CTR2=1) CH1: PWM (DC Decoupling) CH2: VOUT (DC Decoupling) CH3: IOUT (AC Decoupling) REV1.2 - JAN 2007 RELEASED – JUN 2008 REVISED - -7- AiT Semiconductor Inc. www.ait-ic.com A8440 4CHANNEL WHITE LED DRIVER 1x /1.5x CHARGE PUMP DISPLAY BACKLIGHT SOLUTION 17. 100Hz PWM Signal, Vcc=3.2V, 4ILED=60mA Positive Duty Cycle=74% PWM Control Enable (CTR0=0, CTR1=1, CTR2=1) CH1: PWM (DC Decoupling) CH2: VOUT (DC Decoupling) CH3: IOUT (AC Decoupling) REV1.2 - JAN 2007 RELEASED – JUN 2008 REVISED - -8- AiT Semiconductor Inc. www.ait-ic.com A8440 4CHANNEL WHITE LED DRIVER 1x /1.5x CHARGE PUMP DISPLAY BACKLIGHT SOLUTION BLOCK DIAGRAM REV1.2 - JAN 2007 RELEASED – JUN 2008 REVISED - -9- A8440 AiT Semiconductor Inc. www.ait-ic.com 4CHANNEL WHITE LED DRIVER 1x /1.5x CHARGE PUMP DISPLAY BACKLIGHT SOLUTION DETAILED INFORMATION At power-up, the A8440 starts operation in 1x mode. If it is able to drive the programmed LED current, it continues to operate in 1x mode. If the battery voltage drops to a level where the LED current cannot be met, the driver automatically switches into 1.5x mode. The 1.5x charge pump will boost the output voltage accordingly to achieve the nominal LED current. Typical Circuit LED Current Setting The LED current is set by the external resistor RSET connected between the RSET pin and ground. Various LED Currents and The associated RSET resistor value for standard 1% precision surface mount resistors: LED Current (mA) RSET (KΩ) 1 620 2 234.6 5 90 10 44.2 15 30 20 21.0 30 14.5 Table 1. RSET Resistor Selection REV1.2 - JAN 2007 RELEASED – JUN 2008 REVISED - - 10 - A8440 AiT Semiconductor Inc. www.ait-ic.com 4CHANNEL WHITE LED DRIVER 1x /1.5x CHARGE PUMP DISPLAY BACKLIGHT SOLUTION The digital control lines CTR0, CTR1 and CTR2 allow to turn On or Off a combination of LEDs as below: Control Lines LED Outputs CTR2 CTR1 CTR0 0 0 0 0 0 1 0 1 0 0 1 1 1 0 0 1 0 1 1 1 0 1 1 1 LED4 LED3 LED2 LED1 ON ON ON ON ON ON ON ON ON ON ON ON ON Table 2. LED Selection Note: 1 =Logic High (or VIN) ,0 =Logic Low (or GND), - =LED Output OFF Short Circuit Detect/Disable The unused LED channels can also be turned off by connecting the respective LED pins to VOUT. In this case, the corresponding LED driver is disabled and the typical LED sink current is only about 20uA. When the following equation is true on any channel, the driver turns off the LED channel: VOUT – VLED ≤ 1V (LED channel OFF) Note: The A8440 is designed to drive LEDs with forward voltage greater than 1V and is not compatible with resistive loads. PCB Layout For best performance, a solid ground plane is recommended on the back side of the PCB. The ground tails of CIN and COUT should be connected together close to the GND pin of A8440. REV1.2 - JAN 2007 RELEASED – JUN 2008 REVISED - - 11 - A8440 AiT Semiconductor Inc. www.ait-ic.com 4CHANNEL WHITE LED DRIVER 1x /1.5x CHARGE PUMP DISPLAY BACKLIGHT SOLUTION PACKAGE INFORMATION Dimension in TQFN16 (3x3mm) REV1.2 (Unit: mm) - JAN 2007 RELEASED – JUN 2008 REVISED - Symbol Min Nom Max A 0.7 0.75 0.80 A1 0.00 0.02 0.05 A3 - 0.20REF - D - 300 - D2 1.55 1.70 1.80 E - 3.00 - E2 1.55 1.70 1.80 e - 0.50 - L 0.20 0.30 0.40 K 0.20 - - b 0.18 0.25 0.30 - 12 - A8440 AiT Semiconductor Inc. www.ait-ic.com Dimension in QFN16 (4x4mm) REV1.2 4CHANNEL WHITE LED DRIVER 1x /1.5x CHARGE PUMP DISPLAY BACKLIGHT SOLUTION (Unit: mm) - JAN 2007 RELEASED – JUN 2008 REVISED - Symbol Min Nom Max A 0.80 0.90 1.00 A1 0.00 0.02 0.05 A3 - 0.20ref - D - 4.00 - D2 2.00 2.15 2.25 E - 4.00 - E2 2.00 2.15 2.25 e - 0.65 - L 0.45 0.55 0.65 K 0.20 - - b 0.25 0.30 0.35 - 13 - A8440 AiT Semiconductor Inc. www.ait-ic.com 4CHANNEL WHITE LED DRIVER 1x /1.5x CHARGE PUMP DISPLAY BACKLIGHT SOLUTION IMPORTANT NOTICE AiT Semiconductor Inc. (AiT) reserves the right to make changes to any its product, specifications, to discontinue any integrated circuit product or service without notice, and advises its customers to obtain the latest version of relevant information to verify, before placing orders, that the information being relied on is current. AiT Semiconductor Inc.'s integrated circuit products are not designed, intended, authorized, or warranted to be suitable for use in life support applications, devices or systems or other critical applications. products in such applications is understood to be fully at the risk of the customer. Use of AiT As used herein may involve potential risks of death, personal injury, or servere property, or environmental damage. In order to minimize risks associated with the customer's applications, the customer should provide adequate design and operating safeguards. AiT Semiconductor Inc. assumes to no liability to customer product design or application support. AiT warrants the performance of its products of the specifications applicable at the time of sale. REV1.2 - JAN 2007 RELEASED – JUN 2008 REVISED - - 14 -