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LED Buck PFM: Powers LED with Constant Current Starting at 100MV over VF: This is a proof of concept circuit
which needs improvement. The part values shown will run a high efficiency red LED with a Vf of 1.9V from only 2 nicads, right down to 2 volts. For a white LED you will need more batteries and
you must increase the 1.0K resistor to a higher value. Current sensing at a mere 18mV over 1ohm makes this stepdown switcher efficient, but efficiency can be increased by using a larger
inductor, improving transistor switching speed, or by increasing the value of the 1.0K resistor. ... (added 2/05) |
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LED
dimmer uses only two lines: 03/21/02 EDN-Design Ideas / (added 06/03) This circuit provides32 steps of brightness control (from0 to100%) for a backlight or instrument
panel, using just two general-purpose-microprocessor signals. Although the circuit shows the circuit driving white LEDs, the load could also be a dc motor or an incandescent lamp. The
basis of the circuit is a modified Schmitt-trigger relaxation oscillator controlled by MAX5160 digital potentiometer. |
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LED Light Dimmers
uses Only Two Lines: 03/21/02 EDN-Design Ideas / (added 2.06) -The circuit in Figure 1 provides 32 steps of brightness control—from 0 to 100%—for a backlight or
instrument panel, using just two general-purpose-microprocessor signals. In addition, the circuit requires little board space, because it uses only three SOT-23s and one µMax package. Although
Figure 1 shows the circuit driving white LEDs,... |
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LED Torch: Based on the Maxim MAX660, designed to power three 3mm/5mm white LED's from 3V (1.5V min) , intended
for replacing incandescent bulbs in small torches….(electronic design added 6/07) |
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Light
a White LED from Half a Cell: 06/12/03 EDN Design Ideas / (added 1/05) Whether you use them as indicators or to provide illumination, LEDs are hard to
beat in efficiency, reliability, and cost. White LEDs are rapidly gaining popularity as sources of illumination, as in LCD backlights, but with forward voltages typically ranging from 3 to 5V,
operating them from a single cell presents obvious difficulties.... |
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Lighting Management System for Six White LEDs and One RGB or Flash LEDs: National Semiconductor Application Note LP3936 June 2004 (app note added 02/05) |
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Lighting Management System for Six White LEDs and Two RGB or Flash LEDs: National Semiconductor Application Note LP3933 March 2004 (app note added 02/05) |
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Line Powered White LEDs: (electronic circuit added 1/06) |
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LM27961-Dual-Display
White LED Driver with 3/2x Switched Capacitor Boost: National Semiconductor Application Note (app note added 2/06) |
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Optical feedback extends white LEDs' operating life: 1/18/2007) EDN Design Ideas / (added 05/07) PWM-controller loop stabilizes light
output. |
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Parallel White LED Driver: National Semiconductor Application Note LM3595 August 2003 (app note added 02/05) |
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Pong in a 3D LED matrix: If you have ever wanted to play pong on a three dimensional display, then this one is
for you. There are 1,000 white LEDs in the matrix that can refresh at a rate of 60 fps….(project added 6/07) |
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PWM White LED Drivers: (electronic circuit added 4/05) |
