Quick answer: LED types describe different things: SMD and COB identify packaging, while RGB identifies a colour combination (Wikipedia, LED types). These labels can overlap: the WS2812B combines RGB emitters and a control circuit in a surface-mount package (WS2812B datasheet).
Start with what you need the component to do, then compare its package and electrical requirements. This guide covers LED components rather than cataloguing bulb shapes. Use the LED lighting calculator hub when you move from identifying a component to planning a lighting project.
Which LED type fits the job?
Choose by function first. A status indicator and a lighting array have different electrical requirements: Kingbright specifies its indicator below at a typical forward voltage of 1.9 V at 10 mA (Kingbright datasheet), while Cree lists a much higher maximum current for its XP-G3 lighting component (Cree XP-G3 datasheet). The table gives concrete examples, not universal ratings for every device with the same label.
| Type or label | What it tells you | Reference example or distinction |
|---|---|---|
| Through-hole indicator | A component for status indication | Kingbright WP7113ID is a 5 mm lamp; typical forward voltage is 1.9 V at 10 mA (Kingbright datasheet). |
| SMD | Surface-mount package | Cree J Series 2835 measures 2.8 × 3.5 × 0.7 mm (Cree 2835 datasheet). |
| COB | Multiple dies grouped into an emitting area | Cree CXA1512 is a multi-die array with a 9 mm optical source (Cree CXA1512 datasheet). |
| High-power | A device intended for higher drive current | Cree XP-G3 white and royal-blue versions have a maximum drive current of 2000 mA (Cree XP-G3 datasheet). |
| RGB | Red, green and blue emitters | Conventional RGB LEDs typically have a common lead plus a lead for each colour (Wikipedia, LED types). |
| Addressable RGB | RGB emitters with integrated control | WS2812B integrates its control circuit and RGB chip in a 5050 package (WS2812B datasheet). |
Treat these as overlapping descriptions. Asking whether an LED is “SMD or RGB” mixes its physical package with its colour arrangement. Specify both when comparing components.
What is the difference between SMD and COB?
SMD identifies a surface-mount device; COB identifies a chip-on-board array. The useful distinction is the package arrangement, not an automatic ranking of brightness or efficiency. Cree describes the CXA1512 as a multi-die array with a 9 mm optical source (Cree CXA1512 datasheet).
Package numbers help interpret size. Cree's J Series 2835 is 2.8 × 3.5 × 0.7 mm, while its J Series 5050 is 5.0 × 5.0 × 0.7 mm (Cree 2835 datasheet, Cree 5050 datasheet). Those are dimensions of named products, not lumen ratings or promises that every similarly named package behaves identically.
Do not assume SMD means a single emitter. The WS2812B fits RGB emitters and control circuitry into its package (WS2812B datasheet). When choosing between components, compare the emitting area, required current and intended output separately. “COB is always brighter” is not a conclusion supported by a package label.
How do indicator and high-power LEDs differ?
Drive current is a concrete distinction. Kingbright's WP7113ID has a typical forward voltage of 1.9 V and a maximum of 2.3 V at the 10 mA test current; its absolute maximum DC forward current is 30 mA (Kingbright datasheet). The absolute maximum is a limit, not a target operating current.
By comparison, Cree specifies a maximum drive current of 2000 mA for white and royal-blue XP-G3 devices on a 3.45 mm platform (Cree XP-G3 datasheet). Physical size alone therefore does not tell you the current requirement. High-power LEDs need a heat sink to remove heat (Wikipedia, high-power LEDs).
Worked example: an indicator LED resistor
Use the LED resistor calculator for this low-voltage calculation. Assumed inputs: a 5 V DC supply, one LED in series, a 1.9 V forward drop and a target current of 10 mA. The assumed forward drop uses Kingbright's typical value at that current (Kingbright datasheet).
The calculator uses R = (supply voltage − forward voltage × LED count) ÷ current in amperes:
- Convert current: 10 ÷ 1000 = 0.010 A.
- LED voltage drop: 1.9 × 1 = 1.9 V.
- Resistor voltage: 5 − 1.9 = 3.1 V.
- Calculated resistance: 3.1 ÷ 0.010 = 310 Ω.
- The calculator selects the nearest E24 value, 300 Ω: its distance is 310 − 300 = 10 Ω, versus 330 − 310 = 20 Ω for 330 Ω.
- Recalculated current: 3.1 ÷ 300 = 0.010333… A; multiplying by 1000 gives approximately 10.33 mA.
- Resistor power: P = V × I = 3.1 × (3.1 ÷ 300) = 0.032033… W, or approximately 32.03 mW.
The calculator rounds to the nearest resistor value, so its selection raises current slightly in this example. These results hold the assumed forward drop constant; they are a circuit estimate, not a measured operating point.
Are RGB, addressable and white LEDs the same?
No. RGB describes the emitters, addressable describes integrated control, and white describes the resulting light. Conventional RGB LEDs combine red, green and blue emitters, typically with four leads: one common connection and one per colour (Wikipedia, RGB LEDs).
Addressable devices add a driver chip beside the emitters and can be chained using a single data wire (Adafruit, the magic of NeoPixels). That data connection describes control, not the device's entire power connection. See the addressable LED strip guide for the strip-focused topic.
White light needs another distinction: LED emission is nearly monochromatic, and white can be produced through phosphor conversion, colour mixing or a hybrid approach (US Department of Energy, LED basics). Phosphor conversion using blue or ultraviolet emission is the more common method (Wikipedia, white LEDs). Choosing a white-light component is therefore a separate decision from choosing RGB control.
FAQ
What do 2835 and 5050 mean?
They identify package formats associated with dimensions. For the cited Cree products, 2835 measures 2.8 × 3.5 mm in footprint and 5050 measures 5.0 × 5.0 mm (Cree 2835 datasheet, Cree 5050 datasheet); the names alone do not give light output.
Does COB mean one large LED chip?
No. COB can group multiple dies into one emitting area; Cree explicitly calls the CXA1512 a multi-die array (Cree CXA1512 datasheet).
Is every RGB LED addressable?
No. Conventional RGB LEDs typically expose separate colour connections, whereas addressable devices integrate driver circuitry (Wikipedia, LED types, Adafruit, the magic of NeoPixels).
Is OLED another package like SMD?
No. According to Wikipedia's OLED article, OLEDs use an organic emissive layer rather than the crystalline structure of conventional LEDs and are mainly used in displays whose pixels emit their own light without a backlight.
Can I choose the resistor from the LED's colour alone?
Use the intended component's forward voltage and operating current. Kingbright, for example, specifies its WP7113ID's typical 1.9 V forward voltage at 10 mA; those are the component-specific inputs behind the worked example (Kingbright datasheet).
Jack Shi
Founder & editor, LEDaskJack Shi builds and writes LEDask, an independent LED-lighting tools project operated by clooms. He designs the calculators, checks their formulas and reference values against published engineering data, and writes the guides across the site.
