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Texas Instruments LM3445M/NOPB
- Part No.:
- LM3445M/NOPB
- Manufacturer:
- Texas Instruments
- Category:
- LED Drivers
- Package:
- 14-SOIC (0.154", 3.90mm Width)
- Datasheet:
-
LM3445M/NOPB.pdf
- Description:
- IC LED DRIVER OFFL TRIAC 14SOIC
- Quantity:
- Payment:
- Shipping:
Inventory:3,337
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Product details
Overview
LM3445M/NOPB from Texas Instruments is a TRIAC-dimmable, adaptive constant off-time AC/DC buck LED driver controller supporting 80–277 VAC input, delivering >1 A constant LED current with no 120-Hz flicker, and integrating a patented bleeder circuit for reliable TRIAC firing in retrofit lighting applications.
For engineers reviewing the LM3445M/NOPB datasheet, LM3445M/NOPB pinout, LM3445M/NOPB application, or LM3445M/NOPB equivalent, key selection considerations include its 5.85-kHz internal ramp frequency, 1.27-V ISNS current-sense threshold, 230-Ωbleeder resistance, thermal shutdown at 165°C, and compatibility with both forward- and reverse-phase dimmers.
Technical Context
The LM3445M/NOPB implements an adaptive constant off-time control architecture that dynamically adjusts switching frequency (100–300 kHz) based on line voltage and LED string voltage to maintain constant current under varying dimmer conduction angles. Its angle-detect circuit monitors BLDR pin voltage (7.21 V threshold) to decode TRIAC firing angle, generating a proportional 0–4 V ASNS PWM signal.
That ASNS signal is filtered via FLTR1 and compared against a 5.85-kHz sawtooth ramp (1–3 V) to produce a dimming-control DC voltage at FLTR2 (0–750 mV), which directly sets peak switch current. The integrated bleeder MOSFET engages below 7.21 V to supply holding current, ensuring stable TRIAC operation across dimming levels.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 80–277 VAC - supports global mains voltages without reconfiguration |
| LED Current Capability | >1 A - enables high-brightness single-string or multi-LED array driving |
| ISNS Threshold | 1.269 V (typ) - sets precise LED current via external sense resistor (e.g., 1.27 Ω for 1 A) |
| Ramp Frequency | 5.85 kHz - determines dimming resolution and decoding linearity (45°–135° conduction) |
| Bleeder Resistance | 230 Ω (typ) - ensures minimum TRIAC holding current while minimizing standby loss |
| Thermal Shutdown | 165°C (typ), 20°C hysteresis - protects IC during overloads or poor heatsinking |
| VCC UVLO | 6.4 V (falling), 7.7 V (rising) - prevents erratic startup/shutdown during brownout conditions |
| Switching Frequency Range | 100–300 kHz - allows compact magnetics and EMI filtering; varies with VBUCK and load |
Pinout & Package
LM3445M/NOPB is packaged in a 10-pin VSSOP (3.00 mm × 3.00 mm) with exposed thermal pad. Pin functions are validated per TI SNVS570M datasheet Rev M (Nov 2015).
| Pin | Circuit Role | Design Meaning |
|---|---|---|
| ASNS | PWM output of dim decoder | 0–4 V duty-cycle-proportional signal derived from TRIAC conduction angle |
| BLDR | Angle detect & bleeder input | Monitors rectified line to trigger bleeder MOSFET and enable TRIAC firing |
| COFF | Constant off-time setting | RC network here defines minimum off-time, stabilizing switching frequency |
| DIM | I/O dim control interface | Accepts external PWM or outputs synchronized dim signal for master/slave configurations |
| FLTR1 | Dim decoder ramp comparator input | Filtered ASNS voltage compared against 5.85-kHz ramp for dimming decoding |
| FLTR2 | Analog dim reference output | 0–750 mV DC voltage controlling LED current magnitude; also accepts analog dim input |
| GATE | MOSFET gate driver output | Capable of driving N-channel power switch with <0.5 V saturation at 100 mA sink |
| GND | Circuit ground reference | Common return for ISNS, VCC, and all internal comparators and regulators |
| ISNS | Current sense input | High-side sense node; 1.27 V threshold sets LED current via source-resistor feedback |
| VCC | Internal regulator input | 8–12 V supply for control circuitry and gate driver; includes UVLO protection |
Key Features
| Feature | Design Value |
|---|---|
| No 120-Hz flicker | Valley-fill circuit + high-frequency buck control eliminates perceptible flicker in human vision range |
| Adaptive off-time control | Automatically adjusts switching frequency to maintain regulation across 80–277 VAC and varying LED Vf |
| Integrated TRIAC bleeder | On-chip MOSFET + 230-Ωresistor provides programmable holding current without external components |
| Wide dimming compatibility | Works with both leading-edge (TRIAC) and trailing-edge (electronic) dimmers via angle-detect architecture |
| Passive PFC support | Valley-fill topology enables >0.9 power factor without active PFC circuitry or controllers |
| Thermal robustness | 165°C shutdown with 20°C hysteresis and RθJA = 159°C/W (VSSOP) enables reliable operation in enclosed fixtures |
Applications
| Retrofit Residential Lighting | Commercial Downlight Systems |
|---|---|
Use Scenario: Replacing incandescent A19 bulbs in standard E26 sockets using TRIAC wall dimmers. IC Role / Device Role / Timing Role: LM3445M/NOPB acts as the primary AC/DC constant-current controller, decoding dimmer phase angle and regulating LED current without flicker. Use Value: Enables seamless dimming compatibility with legacy dimmers while achieving >85% efficiency at 120 VAC with 14-series LEDs. |
Use Scenario: Driving high-CRI LED modules in recessed troffer fixtures with centralized 0–10 V or DALI dimming retrofits. IC Role / Device Role / Timing Role: LM3445M/NOPB serves as the local dimming decoder and current regulator, interfacing with master dim signals via DIM pin synchronization. Use Value: Eliminates need for external dimming translators; supports daisy-chained DIM wiring for uniform dimming across multiple fixtures. |
| Industrial High-Bay Fixtures | Outdoor Area Lighting |
Use Scenario: Powering 50-W LED arrays in warehouse high-bay luminaires operating on 277 VAC circuits. IC Role / Device Role / Timing Role: LM3445M/NOPB functions as the core buck controller, managing high-current drive (>1 A) and thermal derating across –40°C to +125°C junction range. Use Value: Delivers stable current regulation despite wide input voltage swings and ambient temperature extremes, with built-in thermal shutdown. |
Use Scenario: Streetlight replacement units requiring outdoor-rated, flicker-free dimming across utility-grade 120/240/277 VAC supplies. IC Role / Device Role / Timing Role: LM3445M/NOPB operates as the isolated AC/DC LED driver controller, leveraging valley-fill PFC and bleeder circuit for reliable TRIAC hold in humid environments. Use Value: Achieves >0.92 power factor and passes IEC 61000-3-2 Class C emissions with minimal external components. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar TRIAC-dimmable LED driver controller applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| NCP108X series (e.g., NCP1082DR2G) | Fixed-frequency current-mode flyback controller; requires external TRIAC decoder; no integrated bleeder | Higher BOM count; better suited for isolated designs where safety isolation is mandatory | Select when galvanic isolation is required; LM3445M/NOPB preferred for non-isolated, cost-sensitive buck topologies |
| IRS2541PBF | High-voltage linear LED driver with analog dimming; no switching, no PFC, limited to <350 mA | Lower efficiency (~75%), no dimmer compatibility-requires dedicated 0–10 V or PWM interface | Choose only for ultra-low-cost, low-power (<5 W), non-dimmable indicator-style applications |
Compared with NCP1082DR2G and IRS2541PBF, the LM3445M/NOPB uniquely integrates TRIAC angle detection, bleeder control, and adaptive off-time buck regulation in a single 10-pin VSSOP, enabling compact, flicker-free, high-efficiency dimmable drivers without external decoder ICs or isolation transformers.
Availability
LM3445M/NOPB is available at Aetrix Electronics and suitable for retrofit residential lighting, commercial downlights, industrial high-bay fixtures, outdoor area lighting, and solid-state lighting modules requiring stable component supply and long-term manufacturing continuity.
Supply support for LM3445M/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 global semiconductor leader specializing in analog, embedded processing, and power management technologies, with decades of expertise in LED driver innovation and energy-efficient power conversion.
The LM3445M/NOPB belongs to TI's AC/DC LED driver controller product line, designed specifically for non-isolated, TRIAC-dimmable solid-state lighting applications demanding flicker-free performance, passive PFC, and seamless integration into existing dimmer infrastructure.
FAQ
What is the maximum LED current supported by the LM3445M/NOPB?
The LM3445M/NOPB supports LED currents greater than 1 A, as confirmed in the official datasheet Feature section. Actual current is set by the external ISNS sense resistor value - for example, a 1.27 Ω resistor yields ~1 A (1.269 V / 1.27 Ω). Higher currents require appropriate MOSFET, inductor, and thermal design, but the LM3445M/NOPB's current-sense threshold and gate drive capability are rated for >1 A continuous operation.
Does the LM3445M/NOPB require an external TRIAC decoder IC?
No, the LM3445M/NOPB integrates a complete TRIAC dim decoder, including angle-detect circuitry, ASNS PWM generation, FLTR1/FLTR2 filtering, and ramp comparison. It directly interprets the conduction angle from standard leading-edge dimmers without any external decoder IC - a key differentiator versus controllers like the NCP1082DR2G, which require separate decoding circuitry.
Can the LM3445M/NOPB operate with 277 VAC input?
Yes, the LM3445M/NOPB is explicitly rated for 80–277 VAC input per its datasheet Description and Recommended Operating Conditions. Its valley-fill architecture and adaptive off-time control ensure stable regulation across this full range, making it suitable for North American commercial 277 VAC lighting circuits as well as 120/230 VAC residential systems.
How does the LM3445M/NOPB eliminate 120-Hz LED flicker?
The LM3445M/NOPB eliminates 120-Hz flicker through two coordinated mechanisms: (1) its valley-fill circuit maintains VBUCK above LED string forward voltage for >90% of the AC cycle, and (2) its high-frequency (100–300 kHz) adaptive buck control decouples LED current from rectified line ripple. This dual approach ensures constant current delivery independent of line frequency, meeting IEEE 1789 flicker mitigation guidelines.
What package options are available for the LM3445M/NOPB?
The LM3445M/NOPB is offered exclusively in the 10-pin VSSOP (DGS) package (3.00 mm × 3.00 mm), as indicated by the "M" suffix and confirmed in the Device Information table of the SNVS570M datasheet. While the base LM3445 family includes a 14-pin SOIC variant (LM3445N/NOPB), the LM3445M/NOPB part number specifically denotes the VSSOP version with thermal pad - critical for thermal management in high-power LED drivers.
LM3445M/NOPB Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- -
- Package/Case:
- 14-SOIC (0.154", 3.90mm Width)
- Packaging:
- Tube
- Product Status:
- Active
- Type:
- AC DC Offline Switcher
- Topology:
- Step-Down (Buck)
- Internal Switch(s):
- No
- Number of Outputs:
- 1
- Voltage - Supply (Min):
- 8V
- Voltage - Supply (Max):
- 12V
- Voltage - Output:
- -
- Current - Output / Channel:
- -
- Frequency:
- 30kHz ~ 1MHz
- Dimming:
- Triac
- Applications:
- Lighting
- Operating Temperature:
- -40°C ~ 125°C (TJ)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 14-SOIC
LM3445M/NOPB FAQ
1.How can I place an order for LM3445M/NOPB through Aetrix?
Please submit a Request for Quotation (RFQ) for LM3445M/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 LM3445M/NOPB reliable?
The price and inventory of LM3445M/NOPB are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LM3445M/NOPB is usually 5 days.
3.What payment methods are accepted for LM3445M/NOPB?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LM3445M/NOPB transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LM3445M/NOPB?
LM3445M/NOPB orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LM3445M/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 LM3445M/NOPB?
For technical support, including LM3445M/NOPB datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LM3445M/NOPB requirements.
6.How does Aetrix verify that LM3445M/NOPB is sourced from the original manufacturer or authorized distributors?
All LM3445M/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 LM3445M/NOPB meets industry standards.
7.What is the process for return or replacement of LM3445M/NOPB?
All LM3445M/NOPB units undergo pre-shipment inspection (PSI). If there is an issue with LM3445M/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 LM3445M/NOPB part is unused and in its original packaging.
Return procedure for LM3445M/NOPB:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
LM3445M/NOPB Tags
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