RGB Led

The PomeLabs RGB LED Module (PML-RGB-01) turns three independent light channels — red, green, and blue — into a single controllable color output. A 4-channel analog multiplexer routes Backend MCU signals to each LED channel through precision current-limiting resistors, giving you software-controlled color mixing, brightness modulation, and visual state indication in one compact module.

Revision: v1.0 | Part Number: PML-RGB-01 | Series: PomeLabs Core Kit

Pinout

RGB LED Pinout

Schematic

RGB LED Schematic

Digital Twin

In the PomeLabs App, the PML-RGB-01 is mirrored as a digital twin in both the Playground and inside any Connect Activity. Control each color channel independently from the App — set PWM duty cycles, step through color combinations, or trigger color changes from logic outputs in real time.

Controls — parameters you can set from the App

Red channel select · pin GPOUT0 → SEL1 · toggle / PWM

Controls the SEL1 input of U2 (TMUX1511ESVR) to route signal to the Red LED channel through R1 ( $2\,\Omega$ current limiter).

Green channel select · pin GPOUT1 → SEL2 · toggle / PWM

Controls SEL2 to route signal to the Green LED channel through R2 ( $10\,\Omega$ current limiter).

Blue channel select · pin GPOUT2 → SEL3 · toggle / PWM

Controls SEL3 to route signal to the Blue LED channel through R3 ( $10\,\Omega$ current limiter).

Channel 4 select · pin GPOUT3 → SEL4 · toggle / PWM

Controls SEL4 — fourth mux channel, available for auxiliary use or future expansion.

UART TX — Left / Right ports · serial data sources

Drives USART1/USART2 transmit lines through D1/D2 ESD protection.

Monitors — values streamed back from the module

LED state · U1 (LFST-C19H3WT) · color indicator

Live color state of the RGB LED based on active channel selection. Reflects current R/G/B combination.

UART RX — Left / Right ports · serial data traces

Inbound data from downstream nodes through D1/D2 ESD protection back to the Backend MCU.

Datasheet

1. Overview

The PML-RGB-01 centers on two ICs inside the FE Function block: the LFST-C19H3WT (U1) — a through-hole RGB LED with red, green, and blue emitters in a single package — and the TMUX1511ESVR (U2) — a 4-channel analog multiplexer that routes Backend MCU GPIO signals to the individual LED channels under select-line control.

The architecture separates signal routing from current limiting. U2 handles channel selection via four GPIO-driven select lines (SEL1–SEL4 from GPOUT0–GPOUT3). The current through each LED channel is set by dedicated series resistors: R1 ( $2\,\Omega$ ) on the Red channel and R2, R3 ( $10\,\Omega$ each) on the Green and Blue channels. The resistor values are chosen to balance perceived brightness across the three emitters given their different forward voltages and luminous efficacy.

Two USBLC6-2P6 ESD protection devices (D1, D2) protect both UART communication ports.

2. BOM Components

Ref.	Type	Value / Part	Role on this module
U1	RGB LED	LFST-C19H3WT	Single-package RGB LED with separate red, green, and blue emitters. Each emitter driven independently through its own current-limiting resistor.
U2	4-channel analog multiplexer	TMUX1511ESVR (TI)	Routes Backend MCU GPIO signals to LED channels via select lines SEL1–SEL4. Inputs S1–S4 from MCU; outputs D1–D4 to LED channels. Low on-resistance, wide supply range.
R1	Current-limiting resistor	$2\,\Omega$	Series resistor on Red LED channel. Lower value compensates for Red emitter's lower forward voltage — balances perceived brightness.
R2	Current-limiting resistor	$10\,\Omega$	Series resistor on Green LED channel. Limits Green emitter drive current.
R3	Current-limiting resistor	$10\,\Omega$	Series resistor on Blue LED channel. Limits Blue emitter drive current. Identical to R2.
D1	ESD protection IC	USBLC6-2P6 (ST)	IEC $61000-4-2$ Level $4$ ESD clamp on Left UART port. $3.5\,\mathrm{pF}$ max. SOT-666.
D2	ESD protection IC	USBLC6-2P6 (ST)	IEC $61000-4-2$ Level $4$ ESD clamp on Right UART port. Identical to D1.
R4	Resistor	$4.7\,\mathrm{k\Omega}$	Pull-up resistor on UART lines to $3.3\,\mathrm{V}$ .
p1, p2	Connector	Node headers	Left and Right node connectors exposing $+5\,\mathrm{V}$ , GND, S+, S−, RX/TX, TX/RX.

3. Electrical Specifications

3.1 U1 — LFST-C19H3WT (RGB LED)

3.1.1 Absolute Maximum Ratings

Exceeding these values may permanently damage the LED. Stress ratings only.

Parameter	Red	Green	Blue	Unit
Forward current ( $I_F$ ) continuous	$30$	$30$	$30$	mA
Peak forward current ( $I_{FP}$ , $10\,\mathrm{ms}$ pulse, $10\%$ duty)	$100$	$100$	$100$	mA
Reverse voltage ( $V_R$ )	$5$	$5$	$5$	V
Power dissipation ( $P_D$ )	$65$	$65$	$65$	mW
Operating temperature	$-40$ to $+80$	$-40$ to $+80$	$-40$ to $+80$	°C
Storage temperature	$-40$ to $+85$	$-40$ to $+85$	$-40$ to $+85$	°C

3.1.2 Recommended Operating Condition

Conditions for reliable operation and optimal performance.

Parameter	Red	Green	Blue	Unit
Forward current ( $I_F$ )	$20$	$20$	$20$	mA
Peak forward current ( $I_{FP}$ , $10\,\mathrm{ms}$ pulse, $10\%$ duty)	$50$	$50$	$50$	mA
Operating temperature	$-25$ to $+70$	$-25$ to $+70$	$-25$ to $+70$	°C
Forward voltage ( $V_F$ , at $I_F = 20\,\mathrm{mA}$ )	$2.0$ – $2.4$	$3.0$ – $3.4$	$3.0$ – $3.4$	V
Reverse current ( $I_R$ , at $V_R = 5\,\mathrm{V}$ )	$10$	$10$	$10$	$\mu$ A
Luminous intensity ( $I_V$ , at $I_F = 20\,\mathrm{mA}$ )	$800$ – $1500$	$2000$ – $4000$	$800$ – $1500$	mcd
Dominant wavelength ( $\lambda_d$ )	$620$ – $630$	$520$ – $530$	$465$ – $475$	nm
Viewing angle ( $2\theta_{1/2}$ )	$60$	$60$	$60$	deg

3.2 U2 — TMUX1511ESVR (4-Channel Analog Mux)

3.2.1 Absolute Maximum Ratings

Exceeding these values may permanently damage the device. Stress ratings only.

Parameter	Max Value	Unit
Supply voltage ( $V_{DD}$ )	$5.5$	V
Signal voltage on any I/O pin	$-0.5$ to $V_{DD} + 0.5$	V
Select pin voltage	$-0.5$ to $V_{DD} + 0.5$	V
Continuous current per channel	$\pm 150$	mA
Operating junction temperature ( $T_J$ )	$-40$ to $+125$	°C
Storage temperature ( $T_{stg}$ )	$-65$ to $+150$	°C

3.2.2 Recommended Operating Conditions

Parameter	Min	Typ	Max	Unit
Supply voltage ( $V_{DD}$ )	$1.5$	–	$5.5$	V
Signal path I/O voltage (source/drain pins)	$0$	–	$5.5$	V
Control input voltage (SELx pins)	$0$	–	$5.5$	V
Ambient temperature ( $T_A$ )	$-40$	–	$125$	°C
On-resistance ( $R_{ON}$ )	–	$2$	$4.5$	$\Omega$
On-capacitance ( $C_{ON}$ )	–	$3.3$	$6$	pF
Off-capacitance ( $C_{OFF}$ )	–	$2.5$	–	pF
Bandwidth	–	$3000$	–	MHz
$V_{IH}$ (logic input high voltage)	$1.2$	–	–	V
$V_{IL}$ (logic input low voltage)	–	–	$0.45$	V
Input/Output leakage current (ON-state)	–	$0.05$	–	$\mu$ A

Note: When $V_{DD} < 1.5\,\mathrm{V}$ , the signal path I/O voltage range is limited to $0$ – $3.6\,\mathrm{V}$ . The device supports input voltages beyond the supply rail, up to $V_{DD} \times 2$ (maximum $5.5\,\mathrm{V}$ ) when powered within the recommended range.

4. Channel Select Truth Table

SEL1–SEL4 driven by GPOUT0–GPOUT3 from the Backend MCU. Multiple channels can be active simultaneously for color mixing.

SEL1 (GPOUT0)	SEL2 (GPOUT1)	SEL3 (GPOUT2)	Active Channel	LED Color
H	L	L	S1 → D1 → R1 → Red	Red
L	H	L	S2 → D2 → R2 → Green	Green
L	L	H	S3 → D3 → R3 → Blue	Blue
H	H	L	S1 + S2 → Red + Green	Yellow
H	L	H	S1 + S3 → Red + Blue	Magenta
L	H	H	S2 + S3 → Green + Blue	Cyan
H	H	H	S1 + S2 + S3 → All	White
L	L	L	None	Off

6. Pin Descriptions

All signal pins referenced to GND.

Pin / Net Name	Direction	Description
GPOUT0 → SEL1	Input	Select line 1 from Backend MCU. HIGH enables Red channel route through U2 S1→D1→R1→Red LED.
GPOUT1 → SEL2	Input	Select line 2 from Backend MCU. HIGH enables Green channel route through U2 S2→D2→R2→Green LED.
GPOUT2 → SEL3	Input	Select line 3 from Backend MCU. HIGH enables Blue channel route through U2 S3→D3→R3→Blue LED.
GPOUT3 → SEL4	Input	Select line 4 from Backend MCU. Fourth mux channel for auxiliary use.
5V_Module → VDD3	Power In	$5\,\mathrm{V}$ supply to U2 VDD and LED anode rail.
GND	Ground	Common ground for U2, LED cathodes, and all connectors.
TX_L-1 / RX_L-1	Input / Output	UART Left port through D1 ESD protection.
TX_R-2 / RX_R-2	Input / Output	UART Right port through D2 ESD protection.

7. Connection Guide & Common Errors

Correct power-up sequence:

Connect GND first, shared across all modules.
Connect 5V_Module to a regulated $5\,\mathrm{V}$ source — this powers both U2 VDD and the LED anode rail.
Ensure all SEL lines (GPOUT0–GPOUT3) are LOW before power-up to prevent uncontrolled LED activation.
Drive SEL lines from Backend MCU GPIO outputs. Use PWM for brightness control.

Common wiring errors and consequences:

Mistake	Symptom	Correction
SEL lines driven HIGH continuously at full duty cycle	LED overdriven — reduced lifetime, potential permanent damage	Use PWM to control brightness. Recommended duty cycle $< 50\%$ for continuous operation.
5V_Module supply exceeds $5.5\,\mathrm{V}$	U2 (TMUX1511ESVR) permanently damaged	Keep supply $\leq 5.5\,\mathrm{V}$ .
SEL lines left floating	Random LED activation — undefined mux state	Always drive SEL lines from a defined logic source. Pull to GND if unused.
GND not shared with Backend MCU	SEL logic thresholds shift — unreliable channel switching	Ensure a single common GND bus across all modules.
USBLC6-2P6 VBUS unconnected on D1 or D2	ESD protection ineffective	Connect VBUS of D1 and D2 to 5V_Module.