CIRCUIT AND METHOD FOR CONTROLLING RGB LED COLOR BALANCE USING A VARIABLE BOOSTED SUPPLY VOLTAGE
First Claim
Patent Images
1. A circuit for controlling color balance in an LED, comprising:
- at least one LED;
a charge pump including first and second inputs, two Shottky dioides, a switched capacitor network having a flying capacitor and an output capacitor, and an output node for sending a signal to said at least one LED;
at least one resistor in line with said LED; and
a microprocessor having a first output pin connected to said first input for turning on and off power to said charge pump, and a second output pin connected to said second input for providing a signal and power to said switched capacitor network;
wherein pulsing of said second output pin boosts voltage at said output capacitor and the boosted voltage is maintained by the capacitance at said output node of said charge pump.
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Abstract
A microprocessor uses one or more output pins to pulse width modulate a charge pump network to achieve a boosted voltage on an output port. The boosted voltage is then used to drive an LED, which may have a higher voltage drop than that of the starting un-boosted voltage. The adjustment of either the frequency or duty cycle of the PWM signal allows for adjustment of the steady state output voltage. This allows for the adjustment of the brightness of the LED by firmware while supplying enough voltage drop required by the LEDs.
11 Citations
13 Claims
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1. A circuit for controlling color balance in an LED, comprising:
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at least one LED; a charge pump including first and second inputs, two Shottky dioides, a switched capacitor network having a flying capacitor and an output capacitor, and an output node for sending a signal to said at least one LED; at least one resistor in line with said LED; and a microprocessor having a first output pin connected to said first input for turning on and off power to said charge pump, and a second output pin connected to said second input for providing a signal and power to said switched capacitor network; wherein pulsing of said second output pin boosts voltage at said output capacitor and the boosted voltage is maintained by the capacitance at said output node of said charge pump. - View Dependent Claims (2, 3)
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4. A circuit for controlling RGB LED color balance, comprising:
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an RGB LED array; first, second, and third charge pumps, each including first and second inputs, two Shottky diodes, a switched capacitor network having a flying capacitor and an output capacitor, and an output node for sending a signal to one of the red, green, or blue LEDs in said RGB LED array; at least one resistor in line with each of said LEDs; and a microprocessor having, for each of said first second and third charge pumps, a first output pin connected to said first input for turning on and off power to said charge pump, and a second output pin connected to said second input for providing a signal and power to said switched capacitor network; wherein pulsing of each of said second output pins boosts voltage at each of said output capacitors and the boosted voltage is maintained by the capacitance at each of said output nodes of each of said first through third charge pumps, and wherein the relative intensities of each of said LEDs in said RGB LED array can be adjusted to obtain proper color balance. - View Dependent Claims (5)
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6. A circuit for controlling RGB LED color balance, comprising:
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an RGB LED array including a red LED, a green LED and a blue LED; a red LED charge pump for said red LED, said red LED charge pump including an on/off input and a PWM signal input, Shottky diodes, a switched capacitor network having a flying capacitor and an output capacitor, and an output node for sending a signal said red LED; a green LED charge pump for said green LED, said green LED charge pump including an on/off input and a PWM signal input, two Shottky diodes, a switched capacitor network having a flying capacitor and an output capacitor, and an output node for sending a signal said green LED; a blue LED charge pump for said blue LED, said blue LED charge pump including an on/off input and a PWM signal input, two Shottky diodes, a switched capacitor network having a flying capacitor and an output capacitor, and an output node for sending a signal said blue LED; at least one resistor in line with each of said LEDs; and a microprocessor having a first output pin connected to said on/off input of said red LED charge pump for turning on and off power to said red LED charge pump, a second output pin connected to said PWM signal input of said red LED charge pump for providing a signal and power to said switched capacitor network of said red LED charge pump, a third output pin connected to said on/off input of said green LED charge pump for turning on and off power to said green LED charge pump, a fourth output pin connected to said PWM signal input of said green LED charge pump for providing a signal and power to said switched capacitor network of said green LED charge pump, a fifth output pin connected to said on/off input of said blue LED charge pump for turning on and off power to said blue LED charge pump, and a sixth output pin connected to said PWM signal input of said blue LED charge pump for providing a signal and power to said switched capacitor network of said blue LED charge pump; wherein pulsing of each of said second, fourth and sixth output pins boosts voltage at each output capacitor of each of said switched capacitor networks and the boosted voltage is maintained by the capacitance at each of said output nodes of each of said charge pumps, and wherein the relative intensities of each of said LEDs in said RGB LED array can be adjusted to obtain the proper color balance. - View Dependent Claims (7, 8, 9, 10, 11, 12, 13)
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Specification