Circuitry for current regulated, externally controlled LED driving
A current driver circuit for regulating a light emitting diode (LED) is disclosed. An example driver circuit uses one input node of the driver circuit for controlling both maximum brightness and dimming of an LED coupled to an output node of the driver circuit. The driver circuit supplies a reference voltage (VREF) to its input node. A microcontroller is coupled through a resistor or other resistive component to the input node of the driver circuit and provides the input current, where the input current is adjustable by the resistor value. The driver circuit is configured to drive multiple times the input current from its output node. By adjusting the resistor value the output current of the LED is adjusted. The microcontroller is configured to provide pulse width modulation (PWM). By reducing the duty cycle of the PWM waveform the dimming of the LED can be controlled.
1. A current driver circuit comprising:
an input node adapted to receive an input current;
an output node adapted to drive an output current;
a solid voltage module having a first input coupled to a reference voltage and a second input coupled to the input node, the solid voltage module including an operational amplifier having a non-inverting node coupled to the reference voltage and an inverting node coupled to the input node, the operational amplifier configured to have a voltage of the inverting node the same as the reference voltage;
a current receiving module coupled to an output of the solid voltage module and the input node, the current receiving module configured to drive the input current from the input node; and
a current mirror module coupled to the current receiving module and the output node and configured to receive the input current from the current receiving module and drive an output current from the output node that is multiple times the input current.
2. The circuit of claim 1 , wherein the input node is coupled to a first end of a resistor and a driving voltage is coupled to a second end of the resistor, and wherein the input current is a difference of the driving voltage and the reference voltage divided by a resistor value.
3. The circuit of claim 2 , wherein the current receiving module includes a first transistor, wherein the first transistor is configured to drive the input current from the input node.
4. The circuit of claim 3 , wherein the current mirror module includes a second transistor coupled to the first transistor and coupled back to back to a third transistor, wherein the second transistor is configured to receive the input current and the third transistor is configured to drive the output current.
5. The circuit of claim 2 , wherein the driving voltage is supplied by a microcontroller configured to use pulse width modulation (PWM) to control an average output current of the circuit.
6. The circuit of claim 2 , wherein the resistor value is configured to control the input current and the output current of the circuit.
7. The circuit of claim 2 , wherein the output node is coupled to a light emitting diode (LED).
8. The circuit of claim 7 , wherein the circuit is configured to control a specific LED color and the circuit further includes one or more drivers configured to control one or more LED colors.
9. The circuit of claim 1 , wherein the circuit is included in an integrated circuit incorporated in a chip.
10. The circuit of claim 1 , wherein the output current is between 10 and 1000 times greater than the input current.
11. The circuit of claim 1 , wherein the reference voltage is a band-gap voltage reference.
12. A circuit configured for current regulating of a light emitting diode (LED), the circuit comprising:
a microcontroller configured to generate an output voltage, wherein the output voltage of the microcontroller is configured to incorporate pulse width modulation (PWM);
a current driver including an input node and an output node and configured to receive an input current and to drive an output current, wherein the output current is multiple times the input current, and wherein a reference voltage is supplied at the input node of the current driver, where the current driver includes:
a solid voltage module having a first input coupled to the reference voltage and a second input coupled to the input node, the solid voltage module including an operational amplifier having a non-inverting node coupled to the reference voltage and an inverting node coupled to the input node, the operational amplifier configured to have a voltage of the inverting node the same as the reference voltage;
a current receiving module coupled to an output of the solid voltage module and the input node, the current receiving module configured to drive the input current from the input node; and
a current mirror module coupled to the current receiving module and the output node and configured to receive the input current from the current receiving module and drive an output current from the output node that is multiple times the input current;
a resistor coupled to the output voltage of the microcontroller from a first end and to the input node of the current driver from a second end, wherein the input current is a difference of the output voltage of the microcontroller and the reference voltage divided by a resistor value; and
an LED coupled to the output node of the current driver, wherein the current driver is configured to drive the output current from the LED, the resistor value controls a maximum current of the LED, and an average current of the LED is adjusted by the PWM.
13. The circuit of claim 12 , wherein the microcontroller is configured to change a duty cycle of the PWM waveform and control a brightness of the LED.
14. The circuit of claim 12 , wherein the output current of the current driver is at least 10 times the input current of the current driver.
15. The circuit of claim 12 , wherein the reference voltage is a band-gap voltage reference.