KR102274342B1 - Dim to warm controller for leds - Google Patents

Abstract

A control circuit is provided for a light emitting diode (LED) lighting system that achieves a dim-to-warm effect. The control circuit includes an LED controller, a clamp circuit coupled to the set of warm correlated-color-temperature (“CCT”) LEDs, a switch coupled to the set of cool LEDs, and a feedback circuit coupled to the clamp and switch. The LED controller controls the clamp circuit to clamp a current through the set of warm LEDs based on the input current, and switches on the set of cool LEDs in response to an input current greater than a first threshold level and an input lower than the first threshold level. and control the switch to switch off the set of cool LEDs in response to the current. The feedback circuit configured to switch from a set of warm LEDs to a set of cool LEDs.

Description

DIM TO WARM CONTROLLER FOR LEDS

Cross-reference to related patent applications

This application claims priority to U.S. Provisional Application No. 62/328,523, filed April 27, 2016 and European Provisional Application No. 16173125.2, filed June 6, 2016, the contents of which are incorporated herein by reference as if fully set forth.

FIELD OF THE INVENTION The present invention relates generally to lighting using light emitting diodes (LEDs), in particular to make the LED light braille warmer (having a lower CCT) as the LED light is dimmed by a dimmer. It's about technology.

Incandescent bulbs have aesthetically pleasing lighting properties. For example, incandescent light bulbs gradually become redder (warmer) as the user dims the light by controlling the dimmer to reduce the average current through the light bulb. Although many advances are being made in LED technology, further advances that help achieve the quality of light typically provided by incandescent light bulbs are desirable.

A control circuit is provided for a light emitting diode (LED) lighting system that achieves a minimum brightness-maximum dimming level and a dim-to-warm effect between a maximum brightness-minimum dimming level. The control circuit includes an LED controller, a clamp circuit coupled to the set of warm correlated-color-temperature (“CCT”) LEDs, a switch coupled to the set of cool CCT LEDs, and a feedback circuit coupled to the clamp and switch. The LED controller senses an adjustable magnitude of the input current and controls the clamp circuit to clamp a current through the set of warm CCT LEDs to a clamp current level based on the input current, and in response to an input current greater than a first threshold level and switch on the set of cool CCT LEDs and control the switch to switch off the set of cool CCT LEDs in response to an input current lower than a first threshold level.

In response to the input current exceeding the second threshold level, the feedback circuit is configured to switch the current from the set of warm CCT LEDs to the set of cool LEDs.

1 shows a string of warm LEDs and a string of cool LEDs, both emitting white light, dim-to-warm controlling the currents to each string as the input voltage changes from the minimum current to the maximum current. The circuit is further shown.
2 is an example of the relative currents supplied to the warm LEDs Iw and the cool LEDs Ic over the entire range of input currents.
3 shows various functional units within the dim-to-worm circuit of FIG. 2 ;
4 is a circuit diagram of a dim-to-warm circuit, as well as warm LEDs and cool LEDs.
5 is a graph depicting the ideal CCT of a halogen bulb, as well as a simulated overall CCT of the lamp as light is dimmed from maximum to minimum.
6A-6B show that input currents into four dim-to-worm circuits are provided by a tapped linear driver receiving an analog dimming signal, wherein the four dim-to-worm circuits each produce the same CCT at the same dimming level; shows an embodiment of the present invention, which is used and designed to
Figure 7 is a functional diagram (from the data sheet) of a suitable prior art tapped linear regulator that may be used in the system of Figure 6;
Identical or similar elements are denoted by the same number.

In one embodiment, two series strings of LEDs are used in the lamp. The first string contains the same cool LEDs, such as GaN-based LEDs with tuned phosphor generating a CCT of 4000K. The second string contains the same warm LEDs, such as using the same GaN-based LED dies as the cool LEDs but using a tuned phosphor that generates a CCT of 2200K. In other embodiments, the number of strings and CCTs may be different. Both CCTs are considered white light.

A power source such as a rectified trunk voltage is applied to one end of the two strings, and the other ends of the two strings are connected to different terminals of the dim-to-worm circuit.

An adjustable analog (non-PWM) current is supplied to the input of the dim-to-worm circuit, where the input current level can be adjusted by the user controlling a suitable optical dimmer.

Between the minimum input current and the first input current level, the cool LED string is disconnected by the switch, and all input currents flow through the warm LED string. Therefore, dimming solely controls the brightness of the warm LEDs up to the first input current level. The CCT output of the lamp is a constant warm temperature up to the first input current level.

As the input current is controlled above the first input current level but below the second input current level, the switch closes and a portion of the input current flows through the cool LED string and the current through the warm LED string is clamped to a constant current. Therefore, within this range of input currents, dimming solely controls the brightness of the cool LEDs and the brightness of the warm LEDs remains constant. The CCT output of the lamp is a varying mixture of the two CCTs, the CCT increasing as the input current approaches a second input current level.

As the input current is adjusted above the second input current level up to the maximum current, the cool LEDs remain controlled by the increasing input current, and the current to the warm LEDs gradually decreases from the maximum input current to zero. The lamp's CCT output therefore approaches the CCT of the cool LEDs as the input current level approaches its maximum.

Using this technique, a full range of CCTs of 4000K-2200K is obtained, and since both sets of LEDs output white light, there is a more natural combination of light from different LEDs to generate a varying CCT. Since operation is linear (non-PWM or high frequency switching), no EMI is generated and no filters are required. Because operation is linear, very small linear regulators, including tapped linear regulators, can be used to generate the input current.

In one embodiment, a tapped linear driver is used as the driver for the dim-to-worm circuit. A tapped linear regulator receives voltage from a full wave diode bridge that rectifies the AC mains voltage and continuously supplies current to the different segments of the two LED strings as the DC voltage doubles the AC frequency. This results in a very compact and efficient control system.

1 shows one embodiment. Power supply 10 may be a rectified mains voltage, battery, regulator, or other power supply. The series string of white light cool LEDs 12 has its anode end coupled to a power source 10 , and the series string of white light warm LEDs 14 also has its anode end coupled to a power source 10 . has Depending on the desired maximum light output of the lamp, there may be multiple strings of LEDs of each type, and the strings of LEDs of each type may be connected in parallel so that the strings of LEDs of each type are controlled equally.

Cool LEDs may be conventional commercially available, GaN-based LED dies that emit blue light, with a suitable phosphor deposited over a die such as a YAG phosphor. Other phosphors may be used. Such cool LEDs 12 will typically have a CCT in the 3000-6000K range. In this example, the CCT is 4000K.

The warm LEDs 14 may be conventional commercially available, GaN-based LED dies emitting blue light, with a suitable phosphor deposited over a die, such as a YAG phosphor plus a warmer phosphor emitting yellow or red light. Other phosphors may be used. Such warm LEDs 14 will typically have a CCT in the range 1900-2700K. In this example, the CCT is 2200K.

Since the warm and cool LED dies can be the same type of die, they have the same forward voltage drops. In one embodiment, the same number of LEDs are in each of the strings such that the strings have the same forward voltage drop.

The relative brightness (luminous flux) of the cool LEDs 12 and the warm LEDs 14 is determined by the dim-to-warm circuit 16 . Dim-to-warm circuit 16 may be a three-terminal circuit that outputs separate drive currents for warm LEDs 14 (Iw) and cool LEDs 12 (Ic). The input into the dim-to-warm circuit 16 is an adjustable analog current (input current Iin) from an external current source 18 that sets the overall dimming of the lamp. A low input current Iin results in a low overall brightness of a lamp with a relatively low CCT, and a high input current Iin results in a high overall brightness of a lamp with a relatively high CCT.

2 shows the current Iw through the warm LEDs 14 (corresponding directly to the brightness of the warm LEDs 14) and the current Iw through the warm LEDs 14 (directly corresponding to the brightness of the cool LEDs 12) through the entire range of input currents Iin. ) shows the current Ic1 or Ic2 through the cool LEDs 12 . Current Ic1 represents the current at which the cool LEDs 12 are completely off between the minimum input current Iin(min) and the intermediate input current Iin1, and the current Ic2 indicates that the cool LEDs 12 are slightly off between Iin(min) and Iin1. CCT changes are continuous over the entire Iin range as it represents an on-in current. Dim-to-worm circuit 16 can be designed to achieve either Ic1 or Ic2 current curves.

The minimum input current Iin(min) corresponds to the maximum dimming level (minimum brightest and warmest), and the maximum input current Iin(max) corresponds to the minimum dimming level (brightest and coolest).

The following description assumes that the dim-to-worm circuit 16 outputs a current Ic1. Between Iin(min) and Iin1, the dim-to-warm circuit 16 only outputs a current Iw to drive the warm LEDs 14 with a current proportional to the adjustable input current Iin, so the lamp's CCT output is 2200K. Between Iin1 and In2, the dim-to-warm circuit 16 clamps Iw such that the brightness of the warm LEDs 14 is relatively constant, and Ic1 rises proportionally to the input current Iin. Therefore, between Iin1 and Iin2, the total (perceived) CCT output of the lamp will get cooler and cooler. Between Iin2 and Iin(max), Iw falls and Ic1 still rises in proportion to the input current Iin. The overall CCT of a lamp at various dimming levels is generally consistent with the varying CCT of a halogen lamp or incandescent bulb.

3 is an overall system showing a dim-to-warm circuit 16, a string of warm LED(s) 14, a string of cool LEDs 12, and a dimming control adjustable current source 18 outputting Iin. shows

At Iin below Iin1, control circuit 22 (comparator) keeps switch 24 off so no current flows through cool LEDs 12 and all input current Iin flows through warm LEDs 14 .

When Iin exceeds Iin1, the control circuit 22 turns on the switch 24 so the current Ic through the cool LEDs 12 is generally proportional to Iin. The control circuit 22 also controls the clamp circuit 26 to clamp the current Iw to a fixed level so that the brightness of the warm LEDs 14 does not change between Iin1 and Iin2 (FIG. 2).

When the input current exceeds Iin2, the feedback circuit 28 is forward biased to gradually divert some current to the left leg of the circuit, clamping it to gradually reduce the current Iw through the warm LEDs 14. 26) is controlled.

The resulting Iw and Ic currents in FIG. 3 coincide with the currents Iw and Ic1 in FIG. 2 .

Fig. 4 is a schematic circuit diagram of the system of Fig. 3; The circuit of Figure 4 has two of the terminals coupled to the cathode ends of the series strings of warm and cool LEDs, the third terminal being the vdd local terminal (shown in Figure 4) and the fourth terminal coupled to ground; It can be formed as a four-terminal packaged IC. An adjustable dimming current is coupled to the anodes of the two series strings.

The controllable zener diodes U1 and U2 may be TLV431 adjustable shunt regular by Diodes Inc, the data sheet of which is incorporated herein by reference. A good adjustable shunt regulator has an 18V cathode-anode rating with a reference voltage (threshold voltage) of 1.25V. The Zener diode symbol indicates the function of the shunt regulator, although no Zener diodes are required for shunting. Other controllable shunt regulator circuits may be used. The input control voltage into diodes U1 and U2 controls the clamping voltage. Between the input currents Iin(min) and Iin1 (Fig. 2), diode U1 is nominally non-conducting and the gate of MOSFET M1 is pulled to a high level by pull-up resistor R5 to turn on MOSFET M1. do. Consequently, both input current Iin flows through MOSFET M1 and warm LEDs 14 .

Diode U1, resistors R1, R5, R8, and MOSFET M1 form a current regulator (clamp circuit 26), where the gate voltage of MOSFET M1 determines Iw. The control terminal of the zener diode U1 is coupled to the upper node of the resistor R1. In a particular circuit example, when the input current Iin increases the current Iw to the point where the voltage at the top node of resistor R1 is 1.25 volts, the Zener diode U1 returns to the level required to conduct the clamped current Iw in FIG. It will conduct to clamp the gate voltage. The reference voltage is set at TL431 (represented by Zener diode U1), so a control voltage of 1.25 volts conducts Zener diode U1 sufficiently to maintain a voltage of 1.25 volts at the upper node of resistor R1. Before the control voltage reaches 1.25 volts, Zener diode U1 is off. The clamping by the zener diode U1 starts at Iin1 in FIG. 2 . Therefore, between Iin1 and In2, the current Iw flowing through MOSFET M1 will be clamped to 1.25V/R1. So the value of R1 determines the position of Iin1. Although a specific value of 1.25 volts has been described for the control voltage, any technically feasible control voltage may be used.

Resistors R6, R7 and a second adjustable zener diode U2 (another TL431) act as comparators monitoring the gate voltage of MOSFET M1. Before the current Iw through resistor R1 reaches the clamp current, Zener diode U1 draws a minimum current. Resistor R5 is set by Zener diode D1 and connected to some fixed voltage (filtered by capacitor C1) and pulls the gate of MOSFET M1 to a high level, where the gate voltage is multiplied by the voltage set by Zener diode D1 ( R6+R7)/(R5+R6+R7). When the current through MOSFET M1 reaches the regulator's clamp current Iin1, Zener diode U1 (TL431) conducts to pull the gate voltage to the required level clamping the current through MOSFET M1. This lowers the voltage at the resistor divider formed by resistors R6 and R7, and the divided voltage lowers the control voltage into the controllable zener diode U2 (TL431) below its threshold voltage to operate the zener diode U2 as an open circuit. . By doing so, resistor R4 pulls the gate voltage of MOSFET M2 (switch 24 in FIG. 3) to a high level, turning on MOSFET M2 at the input current Iin1. Since the change in gate voltage is large before and after the current through resistor R1 reaches the clamp current, this circuit is rather insensitive to the spread of the internal reference threshold voltage of the TL431 adjustable shunt regulator. More specifically, if someone attempts to design the fixed turn-on threshold of MOSFET M2 to match the internal reference voltage of the TL431 adjustable shunt regulator, the mismatch can occur due to the spread of the reference voltage. With the techniques presented here, the M2 turn-on threshold is insensitive to its spread as it does not attempt to follow the absolute value of the TL431 adjustable shunt regulator's internal reference voltage.

Capacitor C2 and resistor R10 form a compensation circuitry to maintain closed loop stability.

The operation at the input current Iin2 will now be described. Resistor R3 and Schottky diode D2 form the feedback circuit 28 in FIG. 3 . As soon as the source voltage of MOSFET M2 becomes higher than the source voltage of MOSFET M1 by the forward voltage of Schottky diode D2, some current will be diverted through resistors R3 and R1. The current through resistor R1 now consists of currents from both resistor R3 and MOSFET M1. This is the inflection point at Iin2 in FIG. 2 and the beginning of the roll-off of the current Iw in MOSFET M1. The added current through resistor R1 causes Zener diode U1 to further reduce the gate voltage of MOSFET M1 to maintain the voltage at the top node of resistor R1 at 1.25 volts. A larger resistor R2 shifts Iin2 to the left on the x-axis. The slope of the roll-off is determined by the resistor R3. The higher the value of resistor R3, the less steep the slope. Zener diodes U1 and U2 and resistors R6, R7, R4, and R2 perform the functionality of the control circuit 22 (also referred to as the “LED controller”). More specifically, control circuit 22 controls switch 24 (MOSFET M2) to enable or disable current flow through cool LEDs 12 and warm LEDs 14, as specified above. Controls clamp circuit 26 (current regulator comprising zener diode U1, resistors R1, R5, R8, and MOSFET M1) to clamp the current through. Although control circuit 22 and clamp 26 have been described as including certain elements of the circuit shown in FIG. 4 , in at least some aspects the boundary between control circuit 22 and clamp circuit 26 is completely Notice that the outline is not revealed. For example, while resistors R6 and R7 are described as being part of control circuitry 22 and resistor R5 as being part of clamp circuitry 26 , these resistors are described as being part of both control circuitry 22 and clamp circuitry 26 . cooperate to perform the functions of Those of ordinary skill in the art will recognize that the various elements shown in FIG. 4 may be grouped in different ways to correspond to the elements of FIG. 3 .

Resistor R9, diode D1, and capacitor C1 form a voltage buffer. This ensures that the gate voltages of both MOSFETs are within their limits and that the results of the resistor dividers R5, R6 and R7 are predictable.

If it is not desired to completely turn off the cool LEDs 12 at an input current below Iin1, MOSFET M2 can be controlled to roll off between Iin(min) and Iin1, as shown by Ic2 in Figure 2 have. This can be done by connecting a resistor between nodes vcs2 and vs2 as a leakage path in parallel with MOSFET M2.

Figure 5 shows how the resulting CCT output 34 of the lamp is nominally equivalent to the ideal CCT of a halogen bulb while dimming between 100% and about 10% (minimum dimming).

The system of the present invention does not require high frequency filters and can be made very compact and inexpensive. It can be used with any type of dimming circuit that regulates the analog input current.

6A shows the use of a dim-to-worm circuit 16 with a tapped linear LED driver 40 . Tapped linear LED drivers operating from AC mains voltage are well known and commercially available. The driver 40 may be a MAP9010 AC LED driver 40 by MagnaChip or other suitable driver.

The driver 40 receives the rectified AC signal from the radio diode bridge 42 . The AC signal may be the trunk voltage 44 . A fuse 45 (represented by a resistor symbol) protects the circuit from overcurrents, a capacitor 46 smooths transients, and a transient suppressor 48 limits spikes. The driver 40 senses increasing and decreasing levels of the incoming DC signal and applies currents successively to its four outputs IOUT0-IOUT3, as shown in FIG. 6B. Since only one current is output on any of the four output terminals at a time, at low DC voltage levels that almost exceed the forward voltage of the first group of series LEDs, only IOUT0 is the current to activate the first group of LEDs. to output Near the highest DC voltage level that exceeds the forward voltage of the entire string of LEDs, only IOUT3 outputs a current to activate the entire string. Diodes 49 ensure that all currents only flow into driver 40 . The analog drive currents are controlled by a control signal 50 , for example from a dimmer controlled by the user.

The first group of LEDs on the left is at the most because those LEDs turn on when the DC voltage rises above the forward voltage of the first group of LEDs, and the fourth group of LEDs on the right shows that those LEDs have the highest DC voltage. It is at its minimum because it only turns on when near a level. The currents are progressively increased to IOUT0-IOUT3 to reduce perceptible flicker as the number of active LEDs varies constantly with varying DC levels. 6A , the warm LEDs 14 are provided as a first array of LEDs and the cool LEDs 12 are provided as a second array of LEDs. Although only one cool LED 12 and one warm LED 14 are shown in each group, there may be more LEDs in each group. IOUT0 may be referred to as a first current signal. IOUT1 may be referred to as a second current signal. IOUT2 may be referred to as a third current signal. IOUT3 may be referred to as a fourth current signal. The dim-to-worm circuit 16A may be referred to as a first dim-to-worm circuit. The dim-to-worm circuit 16B may be referred to as a second dim-to-worm circuit. The dim-to-worm circuit 16C may be referred to as a third dim-to-worm circuit. The dim-to-worm circuit 16D may be referred to as a fourth dim-to-worm circuit. The voltage level of the incoming DC signal sensed by driver 40 is a first set of LEDs driven by IOUT0 (one leftmost warm LED 14 and one cool LED 12 shown in FIG. 6A ). The time exceeding the forward voltage of ) may be referred to as the first time. The voltage level of the incoming DC signal is driven by IOUT1 of a second set of LEDs (the leftmost two warm LEDs 14 and two cool LEDs 12 shown in FIG. 6A - i.e. the first set The time exceeding the forward voltage of the LEDs of the first set of LEDs, as well as the warm LED 14 and cool LED 12 immediately to the right of the first set of LEDs, may be referred to as the second time. The voltage level of the incoming DC signal sensed by the driver 40 is a third set of LEDs driven by IOUT2 (the leftmost three warm LEDs 14 and the three cool LEDs shown in FIG. 6A ) The time exceeding the forward voltage of 12)) may be referred to as the third time. The time the voltage level of the incoming DC signal exceeds the forward voltage of the fourth set of LEDs (all of the four warm LEDs 14 and four cool LEDs 12 shown in FIG. 6A ) driven by IOUT3. may be referred to as the fourth time. As shown in FIG. 6B , the first time, the second time, the third time, and the fourth time are all different times.

As a result of the currents IOUT0 - IOUT3 being different at the same dimming level, the combination of currents Ic and Iw to the cool LEDs 12 and warm LEDs 14 is applied to each of the dim-to-warm circuits 16A-16D. adjusted for so the CCT of each group of LEDs at all dimming levels is matched to avoid the lamp's CCT fluctuating from cycle to cycle. Matching the CCT at each dimming level is achieved by adjusting the values of resistors R1, R2, and R3 (FIG. 4). For example, for dim-to-warm circuit 16A that receives IOUT0 current (lowest) for a particular dimming level at which cool LEDs and warm LEDs are simultaneously on, dim-to-warm circuit 16A receives IOUT3 current Apply currents Ic and Iw to cool LEDs and warm LEDs at the same rate as dim-to-warm circuit 16D receiving (highest). A person of ordinary skill in the art can easily select the values of R1, R2, and R3 to maintain the same CCTs for each of the dim-to-warm circuits 16A-16D at any of the dimming levels.

7 shows the functional units in the MAP9010 driver reproduced from its data sheet. MOSFETs 60 are controlled to continuously supply the desired currents at the outputs IOUT0-IOUT3 as the rectified DC voltage varies during AC cycles. An analog dimming signal is applied to terminal RDIM to control the currents at the outputs IOUT0-IOUT3. The operation is further described in a data sheet incorporated herein by reference.

The dim-to-worm circuit 16 described above may be a simple three-terminal IC that can be used with conventional LED drivers that provide variable current for dimming. Dim-to-worm circuit 16 does not require high frequency filtering elements (eg, large capacitors or inductors) so it is easily mounted on a printed circuit board with LEDs. A microprocessor is not required.

While specific embodiments have been shown and described, it will be apparent to those skilled in the art that changes and modifications can be made in broader aspects thereof without departing from the present disclosure, so the appended claims cover all such Changes and modifications are intended to be embraced within the true spirit and scope of the present disclosure as fall within their scope.

Claims (20)

As a circuit,
a diode bridge configured to provide a rectified alternating current (AC) signal;
receiving the rectified AC signal,
applying a first current signal to the first dim-to-warm circuit at a first time other than a second time to drive a first set of light emitting diodes (LEDs), and to drive a second set of LEDs a driver configured to apply a second current signal to a second dim-to-warm circuit at the second time other than one hour, wherein the second set of LEDs are in addition to other LEDs of the first set of LEDs; wherein the first dim-to-warm circuit and the second dim-to-warm circuit have an output that results in the same correlated-color-temperature (CCT) for the first and second sets of LEDs. circuitry configured to provide 2. The circuit of claim 1, wherein the diode bridge is a full wave diode bridge. 3. The circuit of claim 1 or 2, wherein the driver is a tapped linear driver. 3. The circuit of claim 1 or 2, wherein the diode bridge is configured to provide the rectified AC signal from a mains voltage signal supplied to the diode bridge. 3. The method of claim 1 or 2, wherein the current supplied by the first dim-to-worm circuit to drive the first set of LEDs becomes less appreciable as the number of LEDs driven by the driver increases. circuit greater than the current supplied by the second dim-to-warm circuit to drive the second set of LEDs to reduce possible flicker. 3. The method of claim 1 or 2,
an LED of the first set of LEDs closest to the first dim-to-worm circuit; and
the first dim-to-worm circuit
a first diode coupled to; and
an LED of the second set of LEDs closest to the second dim-to-worm circuit; and
the second dim-to-worm circuit
A circuit further comprising a second diode coupled to. 3. The circuit of claim 1 or 2, further comprising a fuse configured to protect the circuit from overcurrent. 3. The circuit of claim 1 or 2, further comprising a capacitor configured to smooth transient currents. 3. The method of claim 1 or 2, wherein the actuator is
detecting at least one of an increase in the rectified AC signal and a decrease in the rectified AC signal;
A circuit configured to generate the first current signal and the second current signal based on sensing at least one of an increase in the rectified AC signal and a decrease in the rectified AC signal. 3. The circuit of claim 1 or 2, wherein the rectified AC signal is determined based on a control signal. 3. The method of claim 1 or 2, wherein each of the first dim-to-worm circuit and the second dim-to-worm circuit provides a first array of LEDs and a second CCT providing a first CCT. a circuit configured to drive a second array of LEDs, wherein each of the first set of LEDs and the second set of LEDs includes LEDs of both the first and second arrays of LEDs. 12. The method of claim 11, wherein the same first number of LEDs in the first array and the LEDs in the second array are driven by the first dim-to-warm circuit, the same second number of LEDs in the first array and A circuit in which a second array of LEDs is driven by the second dim-to-worm circuit. 12. The rectified AC signal of claim 11, wherein the second dim-to-worm circuit is a higher rectified AC signal than a rectified AC signal used by the first dim-to-worm circuit to drive the first set of LEDs. circuit configured to drive the second set of LEDs. 12. The circuit of claim 11, wherein the first and second dim-to-worm circuits are configured to drive the LEDs of the first and second arrays using the same current ratio. As a method,
receiving a rectified AC signal;
applying a first current signal to the first dim-to-warm circuit at a first time other than a second time to drive a first set of light emitting diodes (LEDs); and
applying a second current signal to a second dim-to-warm circuit at the second time other than the first time to drive a second set of LEDs, wherein the LEDs of the second set are other LEDs. in addition to the first set of LEDs, wherein the first dim-to-warm circuit and the second dim-to-warm circuit are the same correlated for the first and second sets of LEDs; A method of providing outputs resulting in color-temperature (CCT). 16. The method of claim 15,
detecting an increase or decrease in the rectified AC signal; and
generating the first current signal and the second current signal based on sensing at least one of an increase in the rectified AC signal and a decrease in the rectified AC signal. 17. The method of claim 15 or 16,
Using each of the first dim-to-worm circuit and the second dim-to-worm circuit to drive a first array of LEDs providing a first CCT and a second array of LEDs providing a second CCT and wherein each of the first set of LEDs and the second set of LEDs includes LEDs of both the first and second arrays of LEDs. 18. The method of claim 17,
driving the same first number of LEDs in a first array and a second array of LEDs by the first dim-to-worm circuit; and
and driving the same second number of LEDs in the first array and LEDs in the second array by the second dim-to-worm circuit. 18. The method of claim 17,
Using the second dim-to-warm circuit, the second rectified AC signal is converted to a higher rectified AC signal than the rectified AC signal used by the first dim-to-warm circuit to drive the first set of LEDs. The method further comprising driving the two sets of LEDs. 18. The method of claim 17,
using the first and second dim-to-worm circuitry to drive the LEDs of the first and second arrays using the same current ratio.

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