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Texas Instruments LM3549SQ/NOPB
- Part No.:
- LM3549SQ/NOPB
- Manufacturer:
- Texas Instruments
- Category:
- LED Drivers
- Package:
- 24-WFQFN Exposed Pad
- Datasheet:
-
LM3549SQ/NOPB.pdf
- Description:
- IC LED DRV RGLTR I2C 24WQFN
- Quantity:
- Payment:
- Shipping:
Inventory:3,183
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Product details
Overview
LM3549SQ/NOPB from Texas Instruments is a high-power sequential RGB LED driver IC with integrated buck-boost DC-DC converter, three 700 mA constant-current low-side drivers (R_OUT/G_OUT/B_OUT), I²C interface, and non-volatile memory for standalone operation in portable video projectors. It supports PWM global brightness control, fault detection (LED open/short, thermal, UVLO, OCP), and operates from 2.7V to 5.5V input.
For engineers reviewing the LM3549SQ/NOPB datasheet, LM3549SQ/NOPB pinout, LM3549SQ/NOPB application, or LM3549SQ/NOPB equivalent, key selection considerations include sequential RGB drive architecture, ±6% current accuracy over temperature, 24-pin WQFN package, EEPROM-programmable current settings per bank, and active fault interrupt via open-drain FAULT pin.
Technical Context
The LM3549SQ/NOPB implements a time-multiplexed sequential drive scheme where only one of R_EN/G_EN/B_EN may be active at a time-priority order is RGB-and the buck-boost converter dynamically adjusts VOUT to match the forward voltage of the enabled LED string, minimizing driver power loss. Its internal architecture integrates switcher control (P1/N1/P2/N2/N3 MOSFETs), current-sense amplifiers per channel, EEPROM-backed register banks (Bank 0–2), and dedicated fault logic that latches error flags into the read-only FAULT register.
Control is dual-mode: hardware-driven via R_EN/G_EN/B_EN and PWM inputs, or register-based via I²C (7-bit address 0x36) with full access to current-setting registers (10-bit resolution per channel), master fader (8-bit), fault mask, and soft-start timing. Standby mode enables register writes and EEPROM programming; EEPROM writes require VIN = 5 V and occur only in standby.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Max Output Current | 705 mA per channel (R/G/B), enabling high-brightness RGB LED strings in compact optical engines. |
| Current Accuracy | ±6% over −30°C to +85°C ambient, ensuring stable color balance without external calibration drift compensation. |
| Input Voltage Range | 2.7V to 5.5V - compatible with single-cell Li-ion (3.0–4.2V) and USB-powered systems without LDO pre-regulation. |
| Peak Efficiency | 95% at buck-boost converter output, reducing thermal load in sealed projector light engines. |
| Switching Frequency | 2.25–2.55 MHz - allows use of small 2.2 µH inductors and low-ESR ceramic capacitors (CIN = 10 µF, COUT = 4.7 µF). |
| I²C Address | 0x36 (7-bit) - avoids conflict with common peripheral addresses in embedded display subsystems. |
| Package | 24-pin WQFN (RTW0024A, 4 mm × 4 mm, 0.5 mm pitch) - optimized for thermal dissipation (θJA = 35–50°C/W) in space-constrained PCB layouts. |
Pinout & Package
The LM3549SQ/NOPB uses a 24-pin WQFN package (package code RTW0024A) with exposed thermal pad. Pin 1 identifier is marked on top view; bottom view shows pin numbering clockwise from pin 1. GND_SW pins (4, 15) are dedicated SMPS ground returns, separate from digital GND (pin 15 shared) to minimize noise coupling into current-sense paths.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| L1 (pins 2,3) | Inductor positive terminal | Connects to high-side switch node (P1) - requires low-inductance layout to minimize switching ringing and EMI. |
| L2 (pins 5,6) | Inductor negative terminal | Connects to low-side switch node (N1/N2) - must tie directly to GND_SW plane for optimal converter stability. |
| VOUT (pins 7,9) | Buck-boost output | Supplies dynamically adjusted voltage to LED anodes; routed with wide copper to handle peak 700 mA pulsed current. |
| R_EN/G_EN/B_EN (pins 10,12,13) | Enable inputs | Asynchronous, priority-ordered (R > G > B) digital enables - no internal debouncing; timing-critical for frame-accurate color sequencing. |
| R_OUT/G_OUT/B_OUT (pins 16–18) | Low-side current sinks | Each drives cathode of respective LED; internal 0.2 Ω on-resistance limits dropout voltage and self-heating at 700 mA. |
| FAULT (pin 19) | Fault interrupt output | Active-low open-drain signal - requires external pull-up; asserts on any unmasked fault (OCP, TSD, UVLO, LED short/open). |
| SDA/SCL (pins 20,21) | I²C interface | Compliant with standard-mode I²C (≤100 kHz); SDA bidirectional, SCL input-only - both require 1.8 kΩ pull-ups per TI recommendation. |
| EN (pin 22) | Global enable | Hardware master enable - pulls device into shutdown (<1 µA) when low; rising edge triggers startup sequence and EEPROM load. |
Key Features
| Feature | Design Value |
|---|---|
| Sequential RGB drive architecture | Enables precise temporal color separation in DLP/LCoS projectors without cross-channel crosstalk or simultaneous conduction losses. |
| Integrated buck-boost converter | Dynamically regulates VOUT from 0.8V to 4.6V to match LED VF, reducing driver dissipation by up to 60% vs. fixed-voltage supply. |
| Three independent 10-bit current banks | Supports white-point calibration across LED aging or temperature drift - each bank stores full R/G/B current settings for runtime switching. |
| EEPROM-based standalone operation | Eliminates need for host MCU during normal operation - after initial I²C calibration, LM3549SQ/NOPB runs autonomously using R_EN/G_EN/B_EN and PWM only. |
| Comprehensive fault detection | Detects and flags LED open/short, thermal shutdown, UVLO, and converter overcurrent - enables fail-safe projector shutdown before optical or thermal damage occurs. |
Applications
| Portable Video Projectors | High-Brightness RGB Laser Illumination |
|---|---|
Use Scenario: Compact pico-projectors requiring sequential RGB illumination synchronized to DMD or LCoS panel refresh cycles. IC Role / Device Role / Timing Role: Primary LED driver controlling red/green/blue LED pulses with microsecond-level timing precision; manages VOUT slew rate to match LED turn-on latency. Use Value: Achieves >95% system efficiency and <2 ms color transition via dynamic VOUT adjustment, enabling battery life extension and reduced thermal throttling. | Use Scenario: Embedded laser phosphor or direct RGB laser modules where individual diode current must be tightly regulated and sequenced. IC Role / Device Role / Timing Role: Constant-current sink for laser diode cathodes; uses R_EN/G_EN/B_EN priority logic to enforce strict emission order and prevent simultaneous lasing. Use Value: ±6% current accuracy ensures consistent luminance and chromaticity across operating temperature, critical for color fidelity in AR/VR displays. |
| Automotive HUD Light Engines | Medical Endoscope Illumination |
Use Scenario: Head-up displays requiring high-luminance RGB sources with rapid on/off cycling and robust fault response under automotive voltage transients. IC Role / Device Role / Timing Role: High-reliability LED driver with UVLO and OCP protection; FAULT pin interfaces directly to vehicle safety controller for immediate shutdown on LED failure. Use Value: Withstands 2.7–5.5V input range and −30°C to +85°C ambient, meeting AEC-Q100 stress requirements without external supervision. | Use Scenario: Sterilizable endoscopic light sources needing precise, flicker-free RGB intensity control for tissue differentiation and low-heat operation. IC Role / Device Role / Timing Role: Medical-grade current regulator with EEPROM-stored calibration data - eliminates recalibration after autoclave cycles or component replacement. Use Value: Soft-start and current-step control (0.64 mA/step) enable smooth brightness ramping, preventing patient startle and preserving image sensor dynamic range. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar high-power sequential RGB LED driver applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| TLC59284PWPR | 16-channel constant-current sink (not sequential); no integrated DC-DC; max 120 mA/channel; SPI interface only. | Suited for static multi-LED arrays (e.g., signage), not time-multiplexed RGB projection. | Select only if system uses external boost supply and requires parallel LED driving with higher channel count. |
| TPS61165DRVR | Single-channel boost LED driver (no RGB sequencing logic); 40V max VOUT; analog/digital dimming only; no EEPROM or fault reporting. | Designed for single-color high-VF LEDs (e.g., white), not RGB color separation or fault-aware systems. | Choose only for cost-sensitive, single-LED applications lacking color timing or safety-critical fault handling. |
Compared with TLC59284PWPR and TPS61165DRVR, the LM3549SQ/NOPB uniquely combines sequential RGB timing control, integrated buck-boost regulation, EEPROM-based calibration storage, and comprehensive fault flagging - making it the sole option for autonomous, high-efficiency portable projector light engines requiring color fidelity and safety compliance.
Availability
LM3549SQ/NOPB is available at Aetrix Electronics and suitable for portable video projectors, automotive HUD light engines, medical endoscope illumination, and high-brightness RGB laser modules requiring stable component supply, long-term lifecycle support, and traceable sourcing.
Supply support for LM3549SQ/NOPB includes scheduled delivery planning, volume procurement assistance, BOM continuity management, traceable sourcing, and lifecycle availability coordination for OEM customers, industrial embedded developers, connected-device designers, and electronics production programs.
Manufacturer
Texas Instruments is a U.S.-based semiconductor company specializing in analog, embedded processing, and power management ICs, with decades of leadership in precision power conversion and LED driver innovation.
The LM3549SQ/NOPB belongs to TI's high-efficiency LED driver product line, engineered specifically for sequential RGB illumination in portable projection and imaging systems where thermal efficiency, timing accuracy, and autonomous operation are critical.
FAQ
What is the primary function of the LM3549SQ/NOPB in a portable video projector?
The LM3549SQ/NOPB serves as the core sequential RGB LED driver, managing time-multiplexed red/green/blue LED pulses with precise timing, dynamically adjusting its buck-boost output voltage to match each LED's forward voltage, and maintaining ±6% current accuracy to ensure stable color balance. In portable video projectors, this enables high-efficiency, flicker-free illumination synchronized to DMD or LCoS panel refresh cycles without external MCU intervention after initial calibration.
Does the LM3549SQ/NOPB require an I²C interface to operate?
No - the LM3549SQ/NOPB supports fully standalone operation after initial I²C calibration. Its integrated EEPROM stores current settings, fader values, and configuration registers; upon power-up with EN high, it automatically loads these values and responds solely to R_EN/G_EN/B_EN and PWM inputs. I²C is required only for initial setup, recalibration, or runtime parameter updates.
How does the LM3549SQ/NOPB handle thermal protection?
The LM3549SQ/NOPB incorporates thermal shutdown (TSD) that engages at TJ ≈ +150°C (typical) and disengages at TJ ≈ +140°C (typical), forcing the device into standby mode. A corresponding TSD flag is set in the FAULT register and can trigger the open-drain FAULT pin (pin 19) if unmasked. This protects against sustained overtemperature conditions while allowing automatic recovery once junction temperature falls below the hysteresis threshold.
What are the key layout considerations for the LM3549SQ/NOPB's buck-boost converter section?
Key layout practices include: (1) placing CIN (10 µF) and COUT (4.7 µF) as close as possible to their respective pins with short, wide traces; (2) routing L1/L2 with minimum loop area and direct connection to GND_SW (pins 4, 15); (3) using solid GND_SW and GND planes separated by split; (4) isolating sensitive analog nodes (R_SENS/G_SENS/B_SENS) from noisy switcher paths; and (5) connecting the exposed thermal pad to a dedicated inner-layer thermal plane with ≥6 thermal vias.
Can the LM3549SQ/NOPB drive LEDs with different forward voltages simultaneously?
No - the LM3549SQ/NOPB is designed for sequential (time-multiplexed) RGB drive, not simultaneous operation. Only one of R_EN/G_EN/B_EN may be active at a time, and the buck-boost converter adjusts VOUT to match the forward voltage of the currently enabled LED. This architecture minimizes power loss and enables high efficiency but prohibits concurrent red/green/blue illumination.
LM3549SQ/NOPB Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- -
- Package/Case:
- 24-WFQFN Exposed Pad
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Active
- Type:
- DC DC Regulator
- Topology:
- Step-Down (Buck), Step-Up (Boost)
- Internal Switch(s):
- Yes
- Number of Outputs:
- 3
- Voltage - Supply (Min):
- 2.7V
- Voltage - Supply (Max):
- 5.5V
- Voltage - Output:
- 4.6V
- Current - Output / Channel:
- 705mA
- Frequency:
- 2.4MHz
- Dimming:
- I2C
- Applications:
- -
- Operating Temperature:
- -30°C ~ 85°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 24-WQFN (4x4)
LM3549SQ/NOPB FAQ
1.How can I place an order for LM3549SQ/NOPB through Aetrix?
Please submit a Request for Quotation (RFQ) for LM3549SQ/NOPB on Aetrix. Our sales agent will provide a competitive quotation and guide you through the order confirmation once you accept the terms.
2.Are the price and stock information for LM3549SQ/NOPB reliable?
The price and inventory of LM3549SQ/NOPB are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LM3549SQ/NOPB is usually 5 days.
3.What payment methods are accepted for LM3549SQ/NOPB?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LM3549SQ/NOPB transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LM3549SQ/NOPB?
LM3549SQ/NOPB orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LM3549SQ/NOPB order is processed, you will receive an email with the shipment details and tracking number.
Note: Tracking information may take up to 24 hours to appear. Express delivery typically takes 3–5 business days.
5.How can I obtain technical support or documentation for LM3549SQ/NOPB?
For technical support, including LM3549SQ/NOPB datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LM3549SQ/NOPB requirements.
6.How does Aetrix verify that LM3549SQ/NOPB is sourced from the original manufacturer or authorized distributors?
All LM3549SQ/NOPB products on Aetrix are procured from qualified distributors and authorized channels. Our dedicated quality assurance team conducts strict verification, including traceability checks and, if necessary, third-party testing. This ensures that LM3549SQ/NOPB meets industry standards.
7.What is the process for return or replacement of LM3549SQ/NOPB?
All LM3549SQ/NOPB units undergo pre-shipment inspection (PSI). If there is an issue with LM3549SQ/NOPB, returns or replacements are accepted under the following conditions:
1.Quantity discrepancies, incorrect items, or visible external defects (such as breakage or corrosion), acknowledged by Aetrix.
2.The issue is reported within 90 days of delivery.
3.The LM3549SQ/NOPB part is unused and in its original packaging.
Return procedure for LM3549SQ/NOPB:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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