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Industrial Router Crystal - 3.2x2.5mm 3225 26M (26.000MHz), 12PF, 10PPM, 20PPM, 30PPM

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Abstract: This article outlines a reference design for a 6A step-down LED driver utilizing the MAX16821. The circuit is capable of driving an individual LED and includes details such as circuit specifications, schematics, circuit descriptions, and performance introductions.

Overview:

This reference design focuses on a 6A step-down LED driver intended for portable projectors. It is built around the PWM high-brightness LED driver MAX16821, which can drive a single LED; to handle RGB tri-color LEDs, three such LEDs would be required.

LED Driver Specifications:

Input Voltage Range (VIN): 10V to 15V

Output Voltage (VLED): 4.5V to 6V

Output Current (ILED): 1.5A to 6A, analog control

Analog Control Voltage: 1.1V to 2.8V, corresponding to an LED current range of 1.5A to 6A

Maximum LED Turn-On Duty Cycle: 50%

Maximum LED Current Rise/Fall Time: < 1μs

Maximum LED Current Ripple: <15% at 6A

Input:

VIN (Connect J1 and J2 to VIN+, J3 and J4 to GND): 10V to 15V input power supply.

On/Off Control (J8): Floating or connect to +5V to enable the driver; shorting J8 disables the board.

PWM Input (J7): PWM dimming input, connected to a PWM signal with an amplitude of 3V to 5V. To ensure that the PWM input can drive Q1 and Q7, the signal source should drive a 300pF load with a rise/fall time of less than 500ns. Since the rise/fall time of the output signal is controlled within 1 μs, any 3 to 4 times PWM signal with a period of 1 μs can be used.

LED Current Control (J6): LED current regulation input. Load 1.1V to 2.8V and adjust the LED current from 1.5A to 5A.

Output:

LED+ (J9, J10): Connected to the LED anode.

LED- (J11, J12): Connect to the LED cathode.

Inductor Current Output (J5): Provides a signal proportional to the LED current. The OUTV voltage is 135 times the R9 voltage.