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A8181 Dataheets PDF



Part Number A8181
Manufacturers AiT Semiconductor
Logo AiT Semiconductor
Description HIGH BRIGHTNESS LED DRIVER
Datasheet A8181 DatasheetA8181 Datasheet (PDF)

AiT Semiconductor Inc. www.ait-ic.com   A8181 36V, 1.2A LED STEP-DOWN HIGH BRIGHTNESS LED DRIVER WITH INTERNAL SWITCH   DESCRIPTION The A8181 is a continuous mode inductive step-down converter, designed for driving single or multiple series connected LEDs efficiently from a voltage source higher than the LED voltage. The device operates from an input supply between 6V and 36V and provides an externally output current up to 1.2A. Depending upon supply voltage and external components, this can p.

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AiT Semiconductor Inc. www.ait-ic.com   A8181 36V, 1.2A LED STEP-DOWN HIGH BRIGHTNESS LED DRIVER WITH INTERNAL SWITCH   DESCRIPTION The A8181 is a continuous mode inductive step-down converter, designed for driving single or multiple series connected LEDs efficiently from a voltage source higher than the LED voltage. The device operates from an input supply between 6V and 36V and provides an externally output current up to 1.2A. Depending upon supply voltage and external components, this can provides up to 24 watts of output power. The A8181 includes the output switch and a high-side output current sensing circuit, which uses an external resistor to set the nominal average output current. FEATURES  Simple low parts count  Internal 36V NDMOS switch  Up to 1.2A output current  Single pin on/off and brightness control using DC voltage or PWM  Soft Start  High efficiency (up to 97%)  Wide input voltage range: 6V to 36V  Output shutdown  Up to 1MHz switching frequency  Inherent open-circuit LED protection  Typical 3% output current accuracy  High-side current sense  Hysteretic control: no compensation  Adjustable constant LED current  Over temperature protection  Available in SOT-25 package Output current can be adjusted by applying an external control signal to the 'ADJ' pin. The ADJ pin will accept either a DC voltage or a PWM waveform. During DC dimming, this will provide a continuous output current that is proportional to the external applied DC voltage. During the PWM dimming, this will provide a gated output current and the average current is proportional to the duty cycle. Applying a voltage of 0.2V or lower to the ADJ pin turns the output off and switches the device into a low current standby state. APPLICATIONS  Low voltage halogen replacement LEDs  Automotive lighting  Low voltage industrial lighting  LED back-up lighting  Illuminated signs  LCD TV backlighting TYPICAL APPLICATION The A8181 is available in SOT-25 Packages. ORDERING INFORMATION Package Type Part Number SOT-25 Note E5 A8181E5R A8181E5VR V: Green Package R : Tape & Reel 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 A8181 36V, 1.2A LED STEP-DOWN HIGH BRIGHTNESS LED DRIVER WITH INTERNAL SWITCH Pin # 1 2 3 4 5 TOP VIEW Symbol Function LX GND ADJ ISENSE VIN Drain of NDMOS switch Ground(0V) Multi-function On/Off and brightness control pin:  Leave floating for normal operation.  Drive to voltage below 0.2V to turn off output current  Drive with DC voltage (0.3V < VADJ < 1.2V) to adjust output current from 25% to 100% of IOUTnom. If the ADJ voltage is larger than 1.2V, the output current is IOUTnom.  Drive with PWM signal from open-collector or open-drain transistor, to adjust output current.  Connect a capacitor from this pin to ground to activate soft-start. (soft-start time is approx.0.06ms/nF) Connect resistor RS from this pin to VIN to define nominal average output current IOUTnom = 0.1/RS Input voltage (6V to 36V). Decouple to ground with 4.7uF or higher X7R ceramic capacitor close to device REV1.0 - APR 2011 RELEASED - -2- AiT Semiconductor Inc. www.ait-ic.com     ABSOLUTE MAXIMUM RATINGS A8181 36V, 1.2A LED STEP-DOWN HIGH BRIGHTNESS LED DRIVER WITH INTERNAL SWITCH VIN, Input Supply Voltage -0.3V to +40V VISENSE, ISENSE Voltage +0.3V to -5V NOTE1 VLX, LX Output Voltage -0.3V to +40V VADJ, Adjust Pin Input Voltage -0.3V to +6V ILX, Switch Output Current 1.5A Maximum Junction Temperature 150°C Operating Temperature Range NOTE2 -40°C to 125°C Storage Temperature Range -55°C to 150°C Lead Temperature (Soldering, 10s) 300°C 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 is not implied. Exposure to absolute maximum rating conditions for extended periods may affect device reliability. NOTE1: VISENSE measured respect to VIN. NOTE2: The A8181 is guaranteed to meet performance specifications from 0°C to 70°C. Specifications over the -40°C to 125°C operating temperature range are assured by design, characterization and correlation with statistical process controls. THERMAL RESISTANCE NOTE3 Package θJA SOT-25 250°C/W NOTE3: Thermal Resistance is specified with approximately 1 square of 1 oz copper. θJC 130°C/W REV1.0 - APR 2011 RELEASED - -3- AiT Semiconductor Inc. www.ait-ic.com     ELECTRICAL CHARACTERISTICS A8181 36V, 1.2A LED STEP-DOWN HIGH BRIGHTNESS LED DRIVER WITH INTERNAL SWITCH Test conditions: VIN =12V, TA = 25°C, unless otherwise noted. Parameter Symbol Conditions Input voltage VIN Under voltage lock out VUVLO VIN Rising UVLO hysteresis VUVLO(HYS) VIN falling Quiescent supply current with output off IQ(OFF) ADJ Pin grounded Quiescent supply current with out.


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