Three-level LED bulb microprocessor-based driver
An LED bulb is described, comprising LEDs within a shell and a driver circuit to operate the LEDs at a plurality of brightness levels. The driver circuit comprises first and second inputs to receive AC, a neutral input, a converter circuit, first and second rectifier circuits, a detector circuit, and a processing circuit. The first rectifier circuit is connected to the first and neutral inputs and rectifies the AC received. The second rectifier circuit is connected to the second and neutral inputs and rectifies the AC received. The detector circuit is connected to the first and second rectifier circuits. The processing circuit has a first and a second processor input, and is connected to the detector circuit. The processing circuit produces a chop signal with a duty cycle based on whether the first or second input is hot. The converter circuit powers the LEDs based on the chop signal.
1. A light emitting diode (LED) bulb comprising:
a shell;
a plurality of LEDs within the shell; and
a driver circuit configured to operate the plurality of LEDs at a plurality of brightness levels, the driver circuit comprising:
a first input configured to receive alternating current (AC);
a second input configured to receive AC;
a neutral input;
a converter circuit connected to the plurality of LEDs;
a first rectifier circuit connected to the first input and the neutral input, the first rectifier circuit configured to rectify the AC received at the first input into direct current (DC);
a second rectifier circuit connected to the second input and the neutral input, the second rectifier circuit configured to rectify the AC received at the second input into DC;
one or more detector circuits, the one or more detector circuits connected to the first rectifier circuit and the second rectifier circuit;
a signal processing circuit having a first processor input and a second processor input, the signal processing circuit connected to the one or more detector circuits; and
wherein the signal processing circuit is configured to produce a chop signal with a duty cycle, the duty cycle based on whether the first input is hot and whether the second input is hot; and
wherein the converter circuit powers the plurality of LEDs at a driving current, the driving current based on the chop signal.
2. The LED bulb of claim 1 , wherein:
the signal processing circuit is configured to determine whether the first input is hot based on a first duration of a first processor signal received at the first processor input;
the first duration of the first processor signal based on time that the first processor signal is above a first threshold voltage;
the signal processing circuit is configured to determine whether the second input is hot based on a second duration of a second processor signal received at the second processor input; and
the second duration of the second processor signal based on time that the second processor signal is above a second threshold voltage.
3. The LED bulb of claim 2 , wherein:
the signal processing circuit is configured to produce the chop signal with the duty cycle set to:
a first duty cycle, in response to determining that the first input is hot and the second input is not hot,
a second duty cycle, in response to determining that the first input is not hot and the second input is hot, and
a third duty cycle, in response to determining that the first input is hot and the second input is hot; and
the first duty cycle, the second duty cycle, and the third duty cycle are not equal.
4. The LED bulb of claim 3 , wherein the third duty cycle is larger than the first duty cycle and the third duty cycle is larger than the second duty cycle.
5. The LED bulb of claim 2 , wherein each of the one or more detector circuits are configured to produce an ON signal in response to receiving an input above a first detector voltage threshold and configured to produce an OFF signal in response to receiving an input below a second detector voltage threshold.
6. The LED bulb of claim 2 , wherein:
the first rectifier circuit is a full-wave bridge rectifier circuit configured to convert AC to direct current (DC); and
the second rectifier circuit is a full-wave bridge rectifier circuit configured to convert AC to DC.
7. The LED bulb of claim 2 , the driver circuit further comprising:
a switch mode power supply (SMPS) circuit, the SMPS circuit configured to produce a pulse width modulated signal; and
wherein the converter circuit is configured to power the plurality of LEDs based on the pulse width modulated signal.
8. The LED bulb of claim 7 , the driver circuit further comprising:
an AND circuit connected to the SMPS circuit and the signal processing circuit, the AND circuit configured to perform an AND operation on the pulse width modulated signal of the SMPS circuit and the chop signal of the signal processing circuit; and
a switch circuit connected to the AND circuit, the switch configured to short the converter circuit to an output of the first rectifier circuit in response to receiving a HIGH signal from the AND circuit.
9. A light emitting diode (LED) bulb driver circuit configured to operate an LED bulb at a plurality of brightness levels, the LED bulb driver circuit comprising:
a first input configured to receive alternating current (AC);
a second input configured to receive AC;
a neutral input;
a converter circuit connected to a plurality of LEDs;
a first rectifier circuit connected to the first input and the neutral input, the first rectifier circuit configured to rectify the AC received at the first input into direct current (DC);
a second rectifier circuit connected to the second input and the neutral input, the second rectifier circuit configured to rectify the AC received at the second input into DC;
one or more detector circuits, the one or more detector circuits connected to the first rectifier circuit and the second rectifier circuit;
a signal processing circuit having a first processor input and a second processor input, the signal processing circuit connected to the one or more detector circuits; and
wherein the signal processing circuit is configured to produce a chop signal with a duty cycle, the duty cycle based on whether the first input is hot and whether the second input is hot; and
wherein the converter circuit powers the plurality of LEDs at a driving current, the driving current based on the chop signal.
10. The driver circuit of claim 9 , wherein:
the signal processing circuit is configured to determine whether the first input is hot based on a first duration of a first processor signal received at the first processor input;
the first duration of the first processor signal based on time that the first processor signal is above a first threshold voltage;
the signal processing circuit is configured to determine whether the second input is hot based on a second duration of a second processor signal received at the second processor input; and
the second duration of the second processor signal based on time that the second processor signal is above a second threshold voltage.
11. The LED bulb driver circuit of claim 10 , wherein:
the signal processing circuit is configured to produce the chop signal with the duty cycle set to:
a first duty cycle, in response to determining that the first input is hot and the second input is not hot,
a second duty cycle, in response to determining that the first input is not hot and the second input is hot, and
a third duty cycle, in response to determining that the first input is hot and the second input is hot; and
the first duty cycle, the second duty cycle, and the third duty cycle are not equal.
12. The driver circuit of claim 11 , wherein the third duty cycle is larger than the first duty cycle and the third duty cycle is larger than the second duty cycle.
13. The driver circuit of claim 10 , wherein each of the one or more detector circuits are configured to produce an ON signal in response to receiving an input above a first detector voltage threshold and configured to produce an OFF signal in response to receiving an input below a second detector voltage threshold.
14. The driver circuit of claim 10 , wherein:
the first rectifier circuit is a full-wave bridge rectifier circuit configured to convert AC to direct current (DC); and
the second rectifier circuit is a full-wave bridge rectifier circuit configured to convert AC to DC.
15. The LED bulb driver circuit of claim 10 , further comprising:
a switch mode power supply (SMPS) circuit, the SMPS circuit configured to produce a pulse width modulated signal; and
wherein the converter circuit is configured to power the plurality of LEDs based on the pulse width modulated signal.
16. The LED bulb driver circuit of claim 15 , further comprising:
an AND circuit connected to the SMPS circuit and the signal processing circuit, the AND circuit configured to perform an AND operation on the pulse width modulated signal of the SMPS circuit and the chop signal of the signal processing circuit; and
a switch circuit connected to the AND circuit, the switch configured to short the converter circuit to an output of the first rectifier circuit in response to receiving a HIGH signal from the AND circuit.