Page 1 of 4 123 ... LastLast
Results 1 to 10 of 32

Thread: Some Chinese designed LEDs are now using resistive series ballast

  1. #1
    Join Date
    Jun 2010
    Posts
    1,923

    Some Chinese designed LEDs are now using resistive series ballast

    One Energy Star certified, as well as non-certified integral ballast LED lamps were evaluated for their construction. They keep finding ways to carve cost, but not always without affecting important performance. These two were using a series linear current regulator.

    Bridge diode x 1
    160v 10.6uF x 1
    3 chip LED elements x 16 connected in series to form 144v, 48 LED chip string.
    China made transistorized linear amplifier regulator x 1.
    Chip resistors to make 8.55 ohm external current setting



    More thorough documentation on cost cutting, practical performance cutting linear LED ballast is explained in an ON SEMI datasheet.
    http://www.onsemi.com/pub/Collateral/AND9041-D.PDF

    Currently, Energy Star specification says
    https://www.energystar.gov/products/...version_2_0_pd

    "All tests shall be conducted with the lamp connected to a supply circuit of rated frequency. For lamps with multiple operating voltages, the lamp shall be operated at 120 volts throughout testing. If the lamp is not rated for 120 volts, it shall be operated at the highest rated voltage. For dimmable or multi-power lamps, measurements shall be taken at the highest wattage setting listed for the model, unless otherwise specified."

    LED Vf shrinks as it warms up, input current remains the same. The amount of energy flared off in transistor is increased.
    As a way of satisfying power factor, the LED industry's answer was to reduce or eliminate DC bus capacitor which lowers light quality parameter by increasing flicker which is not adequately restricted in Energy Star criteria and allows LED products with inferior light quality to slip into the market.

    This documentation is for a series linear drop out LED ballast chip found in an Energy Star certified Greenlite lamp. It has a much sparse implication on performance when deviated from ideal conditions.

    The lamp, Greenlite 9W/LED/OMNI/D (UL 3UT1 E344320. LED board 10th week of 2017. Lamp case code F11 ) is rated for 800 initial lumen and they forecast the time needed for LED elements to deteriorate to 560 lumens (70%) is 15,000 hours. The lamp is listed for use in enclosed fixture. Test in a pancake fixture resulted in an evolution of objectionable chemical odor and the lamp surface reached 230*F.

    According to the Chinese datasheet for linear drop out LED ballast, it is suggested for use with LED street lights as well as those controversial direct wire TLED. Vf change of LED as a function of temperature is very predictable and forward voltage setting can be fine tuned in 3v, 6v, or 9v increments for specific application which leaves manufacturing variations as the only variability. Laboratory testing for Energy Star certification as well as LM-79 testing are conducted on a regulated precision laboratory power supply set to 120.00v and lamp test environment is conducted in precisely temperature controlled space.

    The very nature of linear regulator makes it become less efficient as the voltage difference between LED Vf and line voltage increases and loss of light output as the difference gets too small. Unfortunately, this allows LED lamps to be engineered around lab benchmark conditions and do well while becoming dimmer or inefficient in real life conditions.

    I think every related lighting product qualifications and energy code such as Energy Star should expand to include +5%, -10% line voltage influence on consumption, case temperature and lumen output and flicker and dimming performance to avoid the temptation for tuning LED products for lab conditions. The practice of tuning products for a very narrow test conditions that is not relevant outside of a testing lab seems to be a common Chinese engineering practice to reduce cost by reducing performance. It is very common for many utility power service to have voltage at socket near +5%. This will increase dissipation and lower efficiency as well as raise temperature. Sickening burnt rubber or flux chemical odors I noticed on multiple samples of these Greenlite lamps, general increase in use of organic materials in LED lamps not used in conventional materials and toxic chemical concerns that surfaced on imported goods in the past, chemical analysis as well as health impact study of LED lamp outgas on sensitive domesticated animals such as canaries and humans maybe beneficial.
    Last edited by roger; 09-08-17 at 01:35 PM. Reason: Removed "confidential" information

  2. #2
    Join Date
    Jan 2011
    Location
    United States
    Posts
    6,644
    Honestly, thats incorrect lol. I've been using Greenlite bulbs and the light drops by 1/3 at the 1000 hour mark.


    But anyways- I don't think those chips are resistive ballasts. They act more like dimmers rapidly opening and closing, correct? While not perfect, they are better than capacitive droppers.


    Let me read through the docs you posted.
    What is esoteric knowledge today will be common knowledge tomorrow.

  3. #3
    Join Date
    Jun 2010
    Posts
    1,923
    Quote Originally Posted by mbrooke View Post
    Honestly, thats incorrect lol. I've been using Greenlite bulbs and the light drops by 1/3 at the 1000 hour mark.


    But anyways- I don't think those chips are resistive ballasts. They act more like dimmers rapidly opening and closing, correct? While not perfect, they are better than capacitive droppers.


    Let me read through the docs you posted.
    I meant to say that the China chip for the Greenlite lamp has much sparse description of what happens as you deviate from ideal. The ON SEMI datasheet does a much better job of explaining. These most definitely are linear dropout current regulators. It most definitely is a linear regulator, which means resistive ballast. This is why change in voltage has so much effect on this design.

  4. #4
    Join Date
    Jan 2011
    Location
    United States
    Posts
    6,644
    Quote Originally Posted by Electric-Light View Post
    I meant to say that the China chip for the Greenlite lamp has much sparse description of what happens as you deviate from ideal. The ON SEMI datasheet does a much better job of explaining. These most definitely are linear dropout current regulators. It most definitely is a linear regulator, which means resistive ballast. This is why change in voltage has so much effect on this design.
    If its a resistive ballast, then where is the heat sink or the heat sink requirements? A 9 watt LED would mean that chip gives off about 4 to 5 watts of heat. That amount of heat would burn such a small circuit board to a crisp. As is, why not simply use a plain resistor instead of a expensive chip?
    What is esoteric knowledge today will be common knowledge tomorrow.

  5. #5
    Join Date
    Jun 2010
    Posts
    1,923
    Quote Originally Posted by mbrooke View Post
    If its a resistive ballast, then where is the heat sink or the heat sink requirements? A 9 watt LED would mean that chip gives off about 4 to 5 watts of heat. That amount of heat would burn such a small circuit board to a crisp. As is, why not simply use a plain resistor instead of a expensive chip?
    It's soldered on the metal core circuit board with the LED elements. It goes into a lamp base which heats up to 230 deg F. A plain resistor doesn't change in value. This thing adjusts resistance to hold current constant (as long as the voltage supplied is high enough to allow LEDs to conduct) through varying the resistance. Chips like this are cheap, especially when its entirely made in China.

    This kind of inferior crude ballast is cheap but it is full of compromises. The power supply topology common for fluorescent lamps are vastly superior in almost every way and people should be aware that if they're sold ballast bypass retrofit, the light quality drops.

    A fluorescent electronic ballast using boost active PFC achieves 0.99 PF, <10% THD, fantastic power regulation (constant input power, constant lamp power from 108 to 305v) while delivering steady light with a flicker index of 0.01 or so which is less than incandescent, all while maintaining >90% efficiency.

  6. #6
    Join Date
    Jan 2011
    Location
    United States
    Posts
    6,644
    Quote Originally Posted by Electric-Light View Post
    It's soldered on the metal core circuit board with the LED elements. It goes into a lamp base which heats up to 230 deg F. A plain resistor doesn't change in value. This thing adjusts resistance to hold current constant (as long as the voltage supplied is high enough to allow LEDs to conduct) through varying the resistance. Chips like this are cheap, especially when its entirely made in China.

    This kind of inferior crude ballast is cheap but it is full of compromises. The power supply topology common for fluorescent lamps are vastly superior in almost every way and people should be aware that if they're sold ballast bypass retrofit, the light quality drops.

    A fluorescent electronic ballast using boost active PFC achieves 0.99 PF, <10% THD, fantastic power regulation (constant input power, constant lamp power from 108 to 305v) while delivering steady light with a flicker index of 0.01 or so which is less than incandescent, all while maintaining >90% efficiency.
    Do you have any info on how these chips works? I always assumed that they simply switched on and off very rapidly to maintain a constant current rather than mimicking a variable resistor.
    What is esoteric knowledge today will be common knowledge tomorrow.

  7. #7
    Join Date
    Apr 2006
    Location
    Springfield, MA, USA
    Posts
    3,006
    The simplest approach is a combination of linear regulator and a resistor. The full output current passes through the resistor, and you regulate the value of voltage across the resistor. Constant V across R means constant I.

    The 'linear regulator' could even be a simple transistor.
    https://en.wikipedia.org/wiki/Curren...urrent_sources

    Linear current sources make good sense in small battery powered devices where the parasitic loads of switching regulators eat up any efficiency improvements.

    I agree with Electric Light here: the testing standards should include normal and expected supply voltage variation.

    -Jon

  8. #8
    Join Date
    Oct 2007
    Location
    New Jersey
    Posts
    4,732
    Quote Originally Posted by Electric-Light View Post

    ...I think every related lighting product qualifications and energy code such as Energy Star should expand to include +5%, -10% line voltage influence on consumption, case temperature and lumen output and flicker and dimming performance to avoid the temptation for tuning LED products for lab conditions. ...
    Is there a way to provide public input to the standards? You've clearly given this more than a little thought and seem to have the technical chops to argue your case. You'd be doing something about the weather instead of just complaining about it.

  9. #9
    Join Date
    Jun 2003
    Posts
    6,727
    Quote Originally Posted by Electric-Light View Post

    Some Chinese designed LEDs are now using resistive series ballast
    Sorry, but I think your initial premise is flawed. This doesn't look at all like a simple series resistor (or even a simple linear regulator) to me.

    http://www.onsemi.com/pub/Collateral/NCL30051-D.PDF

    I believe the power that would be lost by a linear regulator would make it impossible to use a linear regulator (or series resistor) for anything over a few watts without including a heavy, bulky transformer.

    It looks to me like they have gone to extreme lengths to squeeze every drop of efficiency out of the total chip/driver/LED package.

  10. #10
    Join Date
    Jun 2010
    Posts
    1,923
    Hey Roger,
    I want to clarify with you that what I posted is not anything that is privileged. It is publicly available on the web following a part number search and the part number was obtained from physical inspection of LED lamp available through the market.

Tags for this Thread

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •