a8431 Allegro MicroSystems, Inc., a8431 Datasheet
a8431
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a8431 Summary of contents
Page 1
... PWM signal when dimming control is required. The high switching frequency of 1.2 MHz allows the use of small inductor and capacitor values. The A8431 is provided in a 0.75 mm nominal height, 6-pin × MLP package lead (Pb) free, with 100% matte tin leadframe plating. ...
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... A8431 Selection Guide Part Number 1500 pieces per 7-in. reel A8431EEHTR-T *Contact Allegro for additional packing options Absolute Maximum Ratings Characteristic SW Pin Voltage OVP Pin Voltage Remaining Pin Voltage Operating Ambient Temperature Maximum Junction Temperature Storage Temperature Pin-out Diagram Terminal List Table ...
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... A8431 ELECTRICAL CHARACTERISTICS Characteristics Input Voltage Range Supply Current Feedback Reference Voltage Feedback Input Current Switch Current Limit Switch Frequency Switch Maximum Duty Cycle Switch Saturation Voltage Switch Leakage Current Enable Input Input Threshold Low Input Threshold High Input Leakage Overvoltage Protection ...
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... A8431 Quiescent Current versus Input Voltage 2.5 2.0 1.5 1.0 0 (V) IN Feedback Bias Current versus Temperature – Temperature (°C) Switch Pin Voltage versus Temperature 300 250 200 150 100 50 0 – Temperature (°C) White LED Driver Constant Current Operating Characteristics Using Typical Application Circuit (Schematic 1) 2 ...
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... SW pin. This pin should be connected to the output capacitor, C2. To disable this feature connect the pin to ground. EN. Setting lower than 0.4 V disables the A8431 and puts the control circuit into the low-power Sleep mode. Greater than 1.5 V fully enables the A8431. ...
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... I LOAD The A8431 has built-in protection to guard against excessive voltage on the SW pin. If the output voltage exceeds the typical level of the Output Overvoltage Rising Limit, V then the overvoltage protection circuitry shuts off the internal ...
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... FB pin and R1, as shown in schematic 2, the LED current can be made to decrease LOAD voltage) increases, the voltage drop across R2 also increases. This causes the voltage increase, and the A8431 reduces I to compensate LOAD current drops and R2 maintains the full FB. ...
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... LED current LOAD By applying a PWM signal directly to the EN pin, the A8431 is turned on or off, and I is either full (as defined by LOAD R1 varying the duty cycle of the PWM signal, the LED brightness can be controlled from off (0% duty cycle) to full (100% duty cycle) ...
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... A8431 Parallel LED Strings The A8431 can be used to power parallel strings of LEDs, which have the same number of LEDs on each string important that the voltage drop is the same across all of the parallel strings, to ensure that all of the LEDs are illuminated and that the current though each string is equal. ...
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... A8431 0.25 1 0.55 6 Copyright ©2003, 2007, Allegro MicroSystems, Inc. The products described here are manufactured under one or more U.S. patents or U.S. patents pending. Allegro MicroSystems, Inc. reserves the right to make, from time to time, such de par tures from the detail spec tions as may be required to per- mit improvements in the per for mance, reliability, or manufacturability of its products ...