American Bright DOB products
Questions & Answers
Product related Question
Q&A List
1. What is DOB?
DOB is abbreviation of the Driver on Board. It means that we design some specific
circuit to integrate the driver circuit into the same PCB board.
2. What’s the difference between safety for DOB and for the conventional
structure (Driver + DC module)?
For the conventional structure, the Driver (switching power supply) transform the
AC input current to DC input current by using the transformer. Then it inputs the
current to the DC LED module constantly.
Current AC LED module use the IC technology to limited the current to let the LED
being driven directly by the AC power input.
3. The design of DOB Driver is constant voltage (CV) or constant current
(CC)? Is there any difference from external CC IC?
It’s similar to the Constant Current structure, but the whole power structure which
is an AC input driving scheme is different.
4. Is there any limits of size/watts?
Currently we can build 3W to 180W AC LED module and 24mm to 345mm module.
We can also provide the customization service for 90-110V/ 120V/ 127V/ 220V/
240-260V/ 260-280V/ 277V.
5. Is there the dimmable solution?
The Dimmable solution is ready. And mainly, there’s two kinds of the dimming
function.
1st type dimming is the whole dark/whole bright: all the LED will be dimmed in the
same time. All the LED will get bright and dark in the same time. This is more like
the conventional light source, but the efficacy will be lower.
2nd type dimming is 3 segment dimming. Because the circuit is driving
sequentially, so such type of module is dimmed sequentially by different
segment. But the efficacy will be higher.
Basically, we can customize the module based on our customer’s requirement.
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Q&A List
6. Can we provide Driver on COB (DCOB) product? Can it be customized?
Yes, we can provide the solution to build the DCOB product by using the ceramic
substrate. For the customization of the DCOB, the cost will be a little bit
expensive.
7. Can DOB Module use in outdoor application?
Yes, we developed water proof module which enhances the water proof
capability for the safety concern. But the Light fixture also needs to have the
water proof function, otherwise the water proof function would not work.
8. If there’s the surge current or high voltage inputs one or two LEDs and
affects the damage, what can we do?
If there’s the higher current or higher voltage input the module, it will start damaging
from the weakest point. If LED is the weakest point, LED will be damaged first. If
the IC is the weakest point, IC will be damage first. Once the LED is malfunction
by inputting high current or high voltage, the DOB will not work after.
For protection of the circuit,
a. Fuse: We embedded the fuse for preventing inrush current and the pulse huge
current when L/N short
b. Varistor: We embedded the varistor to add the surge current protection.
9. Warranty?
2 years warranty. But there are some exclusions, such as the abnormal usage,
abnormal design of luminaire which shorten the AC module’s life. Some cost
down module, we only provide the 1 year warranty.
10. Can you customized for customer, is there any customized criteria?
We can provide the fully customization service for our customer. We can design
the module based on customer’s requirement.
Please provide us the application, target spec, target price, and then we will
provide the proposal for you. Once you accept it, we will build the 3-5 pcs sample
for your confirmation. If this product is ok, we can prepare the mass production
based on customer’s requirement.
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Q&A List
11. The flicker frequency, and is there any
solutions?
120Hz. Yes we can add some E-cap to lower the flicker phenomenon.
12. The efficiency is with DC or AC?
AC efficiency should combine power efficiency and light module efficiency. So the
efficiency of DOB need to compare with AC efficiency which includes the Driver’s
efficacy and the DC LED module.
13. Is there any space for the reflector, will it cause the short of the circuit?
It could be, so please let us know our luminaire and we might be able to
customize for you.
14. Is there thermal issue in DOB product?
The biggest problem of the LED related technology is the heat dissipation. No
matter how we integrate the electrical parts and optical parts, we still need to
solve the heat issue of LED. You need to lower the temperature of top of the IC
needs to be lower than 110 degree and the temperature of the TC needs to be
lower than 75 degree C, so we need to solve the thermal dissipation issue.
And also please check our application note
Some of our product is made by Single layer FR4 or CEM3 and MCPCB. So our
customer need to dispense the thermal glue in the back of the FR4. It can help to
dissipate the heat to the back plate.
Some of our product is made by Duo layer FR4. We added the thermal paste in
the back of the module. So our customer needs to remove the thermal paste in
the back of the FR4. It can help to dissipate the heat to the back plate and
insulate the current.
15. Is there any heat dissipation suggestion, standard heat sink or
reference check point?
This monitor is for LED and IC
For LED, the mounting pad temperature of the hottest LED can’t exceed 75
degree
For IC, the surface temperature of the hottest IC can’t exceed 110 degree
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Q&A List
16. Can we provide the thermal and RA
report?
Yes, but it takes longer time. We suggest that we can use the LM-80 report to replace the
RA report of the module.
17. Can strip DOB be bent?
Yes, but the circuit trace will be damaged if the bending range is too large. We
can also use the FPC to build the flexible strip DOB.
18. How’s the PCB thermal conductivity? Why don’t you use Al MCPCB
We can use both MCPCB and FR4, but it depends on customer’s application
luminaire. Even the DOB is using FR4 substrate, but the heat can be transfer to the
back plate material if the back plate material is well selected.
19. The thermal solution of DOB Driver（Is there any problem with the
shrinkage from such a large LED driver）. The IC tolerance temperature?
The IC tolerance temperature is150oC. This IC is designed for the overheating
protection. The driving current will be lower when the IC is overheat. For Example,
the IC will lower the current (same as lower the Wattage) when the module is overheat. So the heat will decrease, then the IC will keep in such current output. You can
also see the power consumption getting lower (such as 15W module is overheat then
the watts will decrease to 12W)
Some of our IC will shut down 1-2 string of LED in the module if the module is
over-heat. After the temperature is lower, the shut-down LED will be turn on as
normal LED.
Sometimes there’s the blink effect happened, because the heat come up, the
current getting lower, then the temperature is stable, then the current stop. Then the
light will go up and down then we can see the blink effect when the module is
overheat
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Certification related Question
Q&A List
1. Does this DOB module need to pass the safety certifications?
There’s only one standards, UL 8750(OOQA2), regulated the safety of the LED
module in US. In EU, there’s only one standard to regulate the safety which not in
CNS or CQC. We can send our module to pass the safety regulation which
belongs to the module based, but the customers need to pass the luminaires
safety certification. For example, if our module passed the UL8750, the customer
(Luminaire maker) still needs to send whole module to pass UL1598 in US. In
EU, if our module can pass the EN62031. The customer (Luminaire maker) still
needs to pass the LVD Directive and EMC Directive.
2. EMC certification? EMI?
Mostly, current safety regulation about the EMI/EMC belongs to the luminaire
base. The certified lab tested the EMI/EMC with the whole luminaire, then
certified the whole luminaire. Not like the SELV structure. If the switching power
passes the certification, the whole luminaire gets the certification.
In US, the whole regulation is in UL1598 for the general lighting luminaire. For
EU, we need to pass the EMC directive which includes EN55015, EN61547,
EN61000-3-2, and EN61000-3-3.
We did some EMI/EMC test when we developed our DOB module. But the
EMI/EMC test data cannot represent to be the whole testing data of luminaire.
But we can help out customer to pass the certification if customer needs our
assist.
3. Can DOB module pass Hipot test?
The same situation as the EMI test, the Hipot test belongs to the certification of
whole luminaire. For the CE, it’s under the LVD directive, EN60598. For UL, it’s
under the UL1598. Same as EMI. We did HiPot test when we developed our
DOB module. But we use our luminaire which is bought form the market. We
cannot 100% ensure that the customer’s luminaire can pass too. But we can help
out customer to pass the certification if customer needs our assist.
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Certification related Question
Q&A List
4. Is there any protection design for the
surge current?
Our IC is made in TSMC with high voltage process, so the limitation of the surge
is 0.5kV. It can pass the safety regulation generally. If our customer need to
enlarge the window of the surge protection to 1kV, we can also add some
protection device on it.
5. If the DOB module run in voltage is over the normal operation range
(220V-240V) or the AC input is not stable, is there any tolerance of the
DOB module? What will happened if DOB operated under the unstable
status?
The non-stable AC input phenomenon is shown below:
1. Low AC voltage input  Few LEDs will not turn on, but they will be light up.
2. High AC voltage input  the electrical voltage that exceeds the design range
will transform to the heat. And the heat will impact the DOB module. Then the
over-heat protection of DOB module will activate to lower the current input to
DOB module.
6. Can we pass the surge test larger than 2.5kV?
If we add the varistor (VDR) with enough rating in the AC input side, we can pass
the 2.5kV surge test. But the devices will be very large.
7. Can American Bright’s module pass DLC?
Our module can fulfill the DLC product. But sometimes, the luminaire consumes
too much lumen. In these case, it cannot pass the DLC due to the lower the
efficacy.
8. How’s THDi performance (<15%)
For finding the best C/P ration of the current module, current THDi performance
of our standard product is around 20-25%. We can also provide the lower THD
performance. We have also the circuit which can reach 8% THD.
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