A recent inquiry from Australia started with very little information.
The customer sent us a photo of an existing LED module and provided three requirements:
- 295 mm diameter
- 4000K
- CRI 90
This is not unusual.
Many custom LED module projects do not begin with a complete engineering specification. A customer may know the PCB size, color temperature, power or some basic performance requirements, but still need help defining the electrical and optical parameters of the module.
In this case, the information was enough to understand the general direction of the project, but not enough to prepare a meaningful quotation.
We still needed to know the required voltage and either the target lumen output or an approximate power requirement.
That is where custom LED module development often really begins: not with a finished specification, but with turning an incomplete set of product requirements into a workable first design.
Not Every Customer Starts With a Target Lumen Requirement
For an experienced lighting manufacturer, an inquiry may already include PCB dimensions, operating voltage, target lumens, CRI and other detailed requirements.
Other customers may provide much less.
Some know the approximate wattage of the existing product but do not know the required lumen output. Others may have an existing LED board or product sample and simply want a new module that fits the application.
Requiring every customer to define a precise target lumen value before discussing the project is not always realistic.
If only an approximate power requirement is available, NKT can use a candidate LED that we commonly work with to make a preliminary estimate.
However, power alone does not define LED module light output.
Two modules operating at similar power can produce different lumen output because the LED type, luminous efficacy and operating current may be different.
For this reason, a power-based estimate should be treated as a starting point rather than as a substitute for a defined optical requirement.
What Information Is Needed Before a Preliminary Quotation?
The information needed at the quotation stage is not necessarily the same as everything required for the final PCB design.
For a typical white-light custom module, three inputs are particularly important for the first engineering evaluation:
PCB dimensions, CRI requirement and operating voltage or voltage range.
Target lumen output is also very useful. If the customer does not know it, an approximate power requirement can sometimes be used for an initial estimate.
Other details may be finalized later.
For example, an exact mounting-hole pattern usually does not significantly change the preliminary module price unless the mechanical requirement is unusually complex. A standard CCT can also often be finalized later without materially changing the first quotation, while an unusual CCT requirement may need to be considered earlier.
The purpose at this stage is not to finish every detail of the PCB.
It is to establish whether the proposed LED module is technically and commercially practical enough to move forward.
The First Calculation Starts With the Electrical Conditions
Once the basic requirements are understood, NKT normally reviews the customer's available power-supply or driver voltage conditions early in the process.
A suitable LED can then be selected based on the application requirements.
The manufacturer's datasheet provides the starting reference for parameters such as luminous flux, forward voltage, efficacy, CRI and drive current.
For an initial design, the LED's nominal drive condition is a useful place to begin.
From there, we can estimate how many LEDs may be required and what operating current would be needed to reach the required output.
The calculated LED quantity must then be checked against the available PCB area.
This is where several design variables begin interacting:
target output → LED selection → operating current → LED quantity → operating voltage → PCB space
The calculation is preliminary, but by this point it is already much more useful than simply choosing an LED count from the available board area.
For a deeper discussion of LED quantity itself, see how many LEDs a custom LED module should use.
Nominal Current Is a Starting Reference, Not the Only Possible Operating Point
If the target lumen output can be achieved with a reasonable LED quantity near the manufacturer's nominal operating condition, that provides a practical starting design.
Sometimes, however, the required output cannot be reached within the available PCB area at that current.
If only a modest increase in output is required, increasing the operating current may be considered.
But the manufacturer's maximum current rating is not treated as a design target for continuous operation simply because the datasheet allows it.
If the calculated current becomes unnecessarily high, and PCB space permits, another option is to use more LEDs and operate each LED at a lower current.
This becomes particularly important when the customer has requirements for both lumen output and luminous efficacy.
The relationship between current, output and efficacy is discussed separately in what happens when an LED is driven at higher current. The important point during preliminary design is that current and LED quantity are evaluated together rather than independently.
What Does NKT Provide in the Preliminary Proposal?
Once the first calculation is complete, NKT can provide more than a unit price.
Depending on the project, the preliminary proposal can include:
- proposed LED model
- LED manufacturer datasheet
- estimated LED quantity
- estimated operating current required to reach the target output
- operating voltage
- estimated lumen output
- estimated luminous efficacy
- estimated module power
- unit price
These are still preliminary engineering values rather than final prototype measurements.
That distinction matters.
The purpose of this calculation is to give the customer a technically meaningful basis for deciding whether the proposed module should move into detailed development.
Allowing for Optical Losses in the Finished Product
Customers do not always specify whether their requested lumen value refers to the bare LED module or the finished product.
If the module will operate behind a diffuser, lens or optical cover, the light measured from the finished product will normally be lower than the bare module output because of optical transmission losses.
During preliminary development, NKT may therefore allow approximately 10–15% additional module output in some projects when optical losses are expected.
This is not a universal design rule.
The appropriate margin depends on the actual diffuser, lens, cover and optical arrangement. When reliable transmission data are available, those project-specific values provide a better basis than a general allowance.
Driver efficiency should be considered separately. It affects system electrical input power and overall system efficacy rather than acting as an optical transmission loss.
Mechanical Layout Is Confirmed Before the Design Is Finished
Once the customer decides to proceed, the next step is not necessarily to complete the entire electrical design immediately.
NKT normally prepares the PCB layout first so that important mechanical features can be reviewed, including:
- mounting-hole positions
- connector position
- LED positions
The customer can then confirm that the module fits the intended product and that the major mechanical interfaces are correct.
Only after the layout has been confirmed do we normally complete the circuit design.
For customers who need to review the circuit schematic, it can also be provided. Other customers only require the agreed module specifications and PCB layout.
This sequence helps avoid completing detailed electrical work around a PCB arrangement that later needs to change because of the customer's housing or assembly requirements.
Mechanical restrictions can have a significant effect on the usable LED layout, as discussed in how mounting holes, connectors and keep-out areas affect LED PCB layout.
A Prototype Should Verify the Design, Not Replace the Engineering Work
A prototype is important, but NKT does not rely on the prototype stage to determine basic design parameters from scratch.
Before the first prototype is built, the main variables have already been evaluated:
LED selection, estimated quantity, operating current, voltage, expected lumen output, efficacy, power and PCB layout.
The objective is to resolve as many predictable design questions as practical before committing to the first sample.
For an OEM customer, this matters because repeated prototype cycles add both time and cost. A PCB revision can mean another design cycle, another sample build, another shipment and another round of testing in the customer's product.
The goal of preliminary engineering is therefore not simply to produce a drawing.
It is to reduce avoidable redesign before the first prototype is built.
Datasheet Estimates Still Need Actual Module Measurements
Careful preliminary calculations do not eliminate the need for prototype testing.
Datasheet values provide the engineering starting point. The assembled module provides the actual result.
For a white LED module, NKT can measure parameters including:
- luminous flux
- luminous efficacy
- CCT
- CRI
- voltage
- current
If the measured lumen output is only slightly below the intended target, and the selected LED still has appropriate operating margin, a modest adjustment to the operating current may sometimes be enough to reach the required output without changing the PCB.
If the difference is more significant, the design may need to be reviewed again. Depending on the project, that could involve LED selection, LED quantity, operating current or other design parameters.
This is why prototype validation before production remains different from preliminary calculation: one predicts how the design should perform; the other measures how the actual module performs.
The Customer Still Needs to Validate the Module in the Final Product
A successful LED module prototype does not automatically validate the complete lighting product.
After receiving the sample, the OEM customer may install it in the actual housing and evaluate the finished system with its diffuser, lens, heatsink, power supply and real operating environment.
This final-product validation is particularly important because conditions outside the LED module itself can affect optical and thermal performance.
NKT focuses on developing and validating the LED module. The customer evaluates whether that module performs as required in the complete product.
That division of responsibility is important in custom OEM development.
Good LED Module Development Often Starts With Incomplete Information
An OEM customer does not need to arrive with a finished LED module specification.
A photo, PCB dimensions, voltage, approximate power, target output, CRI requirement or an existing module can all provide useful starting information.
What matters is identifying which information is still missing and resolving the important electrical, optical and mechanical questions in the right order.
At NKT, the process is intended to move from:
Initial product requirements
→ preliminary engineering evaluation
→ quotation and proposed module parameters
→ PCB layout confirmation
→ circuit design
→ prototype measurement
→ customer validation in the final product
The more that can be calculated and confirmed before the first prototype, the lower the likelihood of avoidable redesign later.
If you are developing a module for a new OEM product, you do not need to determine every LED parameter before contacting us. Send us the requirements you already have, and NKT can help identify the information needed for the next stage of development.
You can also review NKT's custom OEM LED module development process and NKT's LED module engineering capabilities.