Chip gives dim-to-warm LED lighting without MCU

To simplify incandescent-like LED dimming – where colour temperature (CCT) falls with intensity – Dialog Semi has introduced a single chip dual output power converter that needs no microcontroller.

iW3640 is a 25W 2-channel mains-powered LED driver, intended for 75-150W-equivalent A19 and PAR bulbs, as well as 20-45W commercial dimmable external lighting ballasts.

Chip gives dim-to-warm LED lighting without MCU

It works by producing a PWM signal that gradually increases its duty-cycle as output current is reduced. A set of white LEDs is fed directly from the converter output (see diagram) while a set of amber LEDs is fed from the same output, but modulated by the PWM signal via a mosfet.

In this way, the light output becomes more amber as the light is dimmed.

Various dim/CCT characteristics are possible by altering the number of LEDs in each string, and the arrangement of strings (see diagram below).

“Built-in digital dimming detects the dimmer type and phase, automatically adjusting LED colour mixing in step with light intensity to provide smooth dimming that closely matches the warmth and ambiance of a traditional dimmable incandescent bulb,” said Dialog. “The result is a much more intimate LED lighting experience in residential and commercial settings, where lighting plays an important role in setting the mood.”

Dimmers vary considerably in quality, and dimmer compatibility is a big issue with dimmable LED drivers.

“Dialog’s digital dimming technology allows the iW3640 to work with virtually all phase-cut wall dimmers, including leading-edge dimmers (R-type or R-L type) and trailing-edge dimmers (R-C type), as well as digital dimmers, with flicker-free dimming down to 1% of initial brightness,” claimed the firm. “As the driver detects increased dimming angles, the duty cycle of the secondary LED string is increased. Cycle-by-cycle waveform analysis facilitates fast dimmer setting response.”


For more detail: Chip gives dim-to-warm LED lighting without MCU

Leave a Comment

= 4 + 8

(Spamcheck Enabled)

Read previous post:
Digital Read Serial Circuit
Digital Read Serial using Arduino

This example shows you how to monitor the state of a switch by establishing serial communication between your Arduino and your computer...

Scroll to top