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A8442 Dataheets PDF



Part Number A8442
Manufacturers AiT Semiconductor
Logo AiT Semiconductor
Description 80mA 4-CHANNEL CHARGE PUMP WHITE LED DRIVER
Datasheet A8442 DatasheetA8442 Datasheet (PDF)

AiT Semiconductor Inc. www.ait-ic.com A8442 80mA 4-CHANNEL CHARGE PUMP WHITE LED DRIVER WITH LOW DROPOUT CURRENT SOURCE DESCRIPTION FEATURES The A8442 is a high performance white LED driver. It integrates current sources and automatic mode selection charge pump. The part maintains the high efficiency by utilizing an x1/x1.5 fractional charge pump and low dropout current sources. The small equivalent x1 mode open loop resistance and ultra-low dropout voltage of current source extend the opera.

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AiT Semiconductor Inc. www.ait-ic.com A8442 80mA 4-CHANNEL CHARGE PUMP WHITE LED DRIVER WITH LOW DROPOUT CURRENT SOURCE DESCRIPTION FEATURES The A8442 is a high performance white LED driver. It integrates current sources and automatic mode selection charge pump. The part maintains the high efficiency by utilizing an x1/x1.5 fractional charge pump and low dropout current sources. The small equivalent x1 mode open loop resistance and ultra-low dropout voltage of current source extend the operating time of x1 mode and optimize the efficiency of Li-ion battery in white LED applications. The A8442 supports up to 4 white LEDs and regulates a constant current for uniform intensity. The part implements a 4-bit DAC for brightness control. Users can easily configure the LED current from 1.25mA to 20mA by a serial pulse. The dimming of white LEDs current can be achieved by applying a pulse signal to the EN pin. There are totally 16 steps of current could be set by users. The operating voltage range is 2.7V to 5.5V. Internal soft start circuitry effectively reduces the in-rush current while both start-up and mode transition. The load is disconnected from VIN while shutdown and the shutdown current is less than 1μA.  90% Average Efficiency Over Battery Life  Support up to 4 White LEDs  80mV Typical Current Source Dropout  Support up to 80mA Output Current  2% Typical LED Current Accuracy  1% Typical LED Current Matching  High Active  Soft Start Function  Auto Charge Pump Mode Selection  500kHz Fixed Frequency Oscillator  Output Over Voltage Protection  16-Step Brightness Control  Low Input Noise and EMI  Low 1μA Shutdown Current  Available in QFN16(3x3) Package APPLICATION  Mobile Phone, DSC, MP3  White LED Backlighting  LCD Display Supply The A8442 is available in QFN16(3x3) package. TYPICAL APPLICATION ORDERING INFORMATION Package Type Part Number QFN16(3x3) A8442Q16R A8442Q16VR Note R: Tape & Reel V: Green Package AiT provides all Pb free products Suffix “ V “ means Green Package REV1.0 -APR 2011 RELEASED - -1- AiT Semiconductor Inc. www.ait-ic.com PIN DESCRIPTION A8442 80mA 4-CHANNEL CHARGE PUMP WHITE LED DRIVER WITH LOW DROPOUT CURRENT SOURCE Pin # 1 2 3 4 5 6 7 8 9,15 10 11 12 13 14 16 Exposed Pad Symbol C1N C2N C2P C1P AGND PGND VIN EN NC LED4 LED3 LED2 LED1 VOUT VNG GND Top View Function Negative Terminal of Bucket Capacitor 1 Negative Terminal of Bucket Capacitor 2 Positive Terminal of Bucket Capacitor 2 Positive Terminal of Bucket Capacitor 1 Analog Ground Power Ground Power Input Voltage Chip Enable (Active High), and connects to GPIO pin of MCU No Internal Connection Current Sink For Led4. (If Not In Use ,Pin Should Be Connected To GND) Current Sink For Led3. (If Not In Use ,Pin Should Be Connected To VIN) Current Sink For Led2. (If Not In Use ,Pin Should Be Connected To VIN) Current Sink For Led1. (If Not In Use ,Pin Should Be Connected To VIN) Output Voltage Source for LED1 to LED4 charge pump output exposed pad should be soldered to PCB board and connected to GND REV1.0 -APR 2011 RELEASED - -2- AiT Semiconductor Inc. www.ait-ic.com A8442 80mA 4-CHANNEL CHARGE PUMP WHITE LED DRIVER WITH LOW DROPOUT CURRENT SOURCE ABSOLUTE MAXIMUM RATINGS Input Voltage −0.3V to 6V Output Voltage −0.3V to 6V EN Voltage −0.3V to 6V Power Dissipation, PD @ TA = 25°C QFN−16(3X3) 1.47W Package Thermal Resistance QFN−16(3x3), θJA 68°C/W Junction Temperature 150°C Lead Temperature (Soldering, 10 sec.) 260°C Junction Temperature Range −40°C to 125°C Storage Temperature Range −65°C to 150°C ESD Susceptibility HBM (Human Body Mode) 3kV MM (Machine Mode) 200V 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. REV1.0 -APR 2011 RELEASED - -3- AiT Semiconductor Inc. www.ait-ic.com A8442 80mA 4-CHANNEL CHARGE PUMP WHITE LED DRIVER WITH LOW DROPOUT CURRENT SOURCE ELECTRICAL CHARACTERISTICS TA = 25°C, Otherwise specified Parameter Symbol Conditions Min Typ Max Input Supply Voltage V IN 2.7 - 5.5 Undervoltage Lockout Threshold VUVLO VIN rising or falling 1.8 2.0 2.4 Undervoltage Lockout Hysterresis - 100 - Shutdown Current ISHDN VIN = 4.2V, EN = LOW - 1 10 Quiescent of x1 Mode IQ×1 x1 Mode, VIN = 5.5V, LED off - 1 - ILED Accuracy ILED-ERR 2mA < ILED < 20mA -28 Current Matching ILED-LED-ERR 2mA < ILED < 30mA -15 ×1 mode to ×1.5 mode Transition voltage(VIN falling) VLED = 3.4V, VTRANS - 3.5 - ILED1=ILED2=ILED3=ILED4=15mA Oscillator Frequency FOSC VIN-VOUT - 500K - Output Over Voltage Protection VOVP - 5.5 6 Thermal Shutdown Threshold - 150 - Thermal Shutdown Hysteresis - 10 - EN Low Time for Shut Down TSHDN 2- - EN Low Time for Dimming TLO.


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