2 messages2011-05-16 21:31 UTCthrough 2011-05-16 21:41 UTC
LED Bulbs - Who knew?
Husar, Charlie [USA]2011-05-16 21:31 UTC
I would have never imagined that making LED bulbs would get so complicated. Almost a dang computer in every one of them. When incandescents are banned, Mr. Edison will roll over in his grave.
I will suppose that the boat 12V applications are/will be much simpler. I'd just string some LEDs together in series with a pad resistor and hang it from the cabin ceiling with duct tape.
Cheers
Charlie
By: Margery Conner
Use cheaper LEDs while maintaining light quality with dual-string LED controller
EDN Magazine
May 16, 2011
Warm-white LEDs tend to be more expensive than their more-efficacious versions that have a colder blue tinge. LED light manufacturers have a variety of schemes to provide the warmer white colors that consumers associate with the familiar-but-soon-to-be banned incandescent lights: Cree has its TrueWhite approach, which uses red LEDs inside the white-LED module that only turn on at full-on power. Pharox LED bulbs incorporate a few always-on red LEDs in the bulb to achieve a warmer white without the added intelligence of the TrueWhite approach. (For more on this approach see LED bulbs reveal different design approaches.)
Marvell is targeting lighting manufacturers' desire to use lower-cost LEDs in lighting luminaires and bulbs with its new single chip dual-string dimmable 8800 LED lighting controller family. The first member of the family, the 88EM8801, is a single 4X4 millimeter chip that can independently control the current in two separate strings of LEDs, allowing lighting manufacturers to "tune" each string, enabling the use of lower-cost, less-tightly-binned LEDs while still maintaining a uniform light and color temperature.
The chip's architecture is a dual-channel DC/DC synchronous buck converter with integrated MOSFETs: The first string driver can provide up to 1A of drive current, and the second string up to 500mA. The chip has an on-chip OTP (one-time programmable) memory block for compensation and calibration data, and an I2C interface for OTP memory programming and communication with wireless lighting controls such as ZigBee, Wi-Fi and PLC. It uses intelligent pulse-width modulation (PWM) dimming controller circuitry and other digital controls to achieve deep dimming levels to 0.1 percent. No word yet on pricing.
RE: [Cal_Boats] LED Bulbs - Who knew?
Brian Hess2011-05-16 21:41 UTC
Don't go through all the trouble and expense. . . just do what was done for
thousands of years and use a lantern or oil lamp . . perhaps a candle and a
hurricane lamp! That's what I do. And you don't need to worry about
batteries! It's cheaper with lamp oil!
Brian
From: Ca… [at] yahoogroups.com [mailto:Ca… [at] yahoogroups.com] On Behalf
Of Husar, Charlie [USA]
Sent: Monday, May 16, 2011 2:32 PM
To: Ca… [at] yahoogroups.com
Subject: [Cal_Boats] LED Bulbs - Who knew?
I would have never imagined that making LED bulbs would get so complicated.
Almost a dang computer in every one of them. When incandescents are banned,
Mr. Edison will roll over in his grave.
I will suppose that the boat 12V applications are/will be much simpler. I'd
just string some LEDs together in series with a pad resistor and hang it
from the cabin ceiling with duct tape.
Cheers
Charlie
By: Margery Conner
Use cheaper LEDs while maintaining light quality with dual-string LED
controller
EDN Magazine
May 16, 2011
Warm-white LEDs tend to be more expensive than their more-efficacious
versions that have a colder blue tinge. LED light manufacturers have a
variety of schemes to provide the warmer white colors that consumers
associate with the familiar-but-soon-to-be banned incandescent lights: Cree
has its TrueWhite approach, which uses red LEDs inside the white-LED module
that only turn on at full-on power. Pharox LED bulbs incorporate a few
always-on red LEDs in the bulb to achieve a warmer white without the added
intelligence of the TrueWhite approach. (For more on this approach see LED
bulbs reveal different design approaches.)
Marvell is targeting lighting manufacturers' desire to use lower-cost LEDs
in lighting luminaires and bulbs with its new single chip dual-string
dimmable 8800 LED lighting controller family. The first member of the
family, the 88EM8801, is a single 4X4 millimeter chip that can independently
control the current in two separate strings of LEDs, allowing lighting
manufacturers to "tune" each string, enabling the use of lower-cost,
less-tightly-binned LEDs while still maintaining a uniform light and color
temperature.
The chip's architecture is a dual-channel DC/DC synchronous buck converter
with integrated MOSFETs: The first string driver can provide up to 1A of
drive current, and the second string up to 500mA. The chip has an on-chip
OTP (one-time programmable) memory block for compensation and calibration
data, and an I2C interface for OTP memory programming and communication with
wireless lighting controls such as ZigBee, Wi-Fi and PLC. It uses
intelligent pulse-width modulation (PWM) dimming controller circuitry and
other digital controls to achieve deep dimming levels to 0.1 percent. No
word yet on pricing.