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Texas Instruments LM3445MM/NOPB
- Part No.:
- LM3445MM/NOPB
- Manufacturer:
- Texas Instruments
- Category:
- LED Drivers
- Package:
- 10-TFSOP, 10-MSOP (0.118", 3.00mm Width)
- Datasheet:
-
LM3445MM/NOPB.pdf
- Description:
- IC LED DRIVER OFFL TRIAC 10VSSOP
- Quantity:
- Payment:
- Shipping:
Inventory:1,455
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Product details
Overview
LM3445MM/NOPB from Texas Instruments is a TRIAC-dimmable, adaptive constant off-time AC/DC buck LED driver controller designed for offline solid-state lighting. It operates across 80–277 VAC input, delivers >1 A LED current, supports 5.85 kHz internal ramp frequency, integrates bleeder circuitry for TRIAC hold current, and eliminates 120-Hz flicker via valley-fill PFC architecture - used in retrofit LED lamps with standard wall dimmers.
For engineers reviewing the LM3445MM/NOPB datasheet, LM3445MM/NOPB pinout, LM3445MM/NOPB application, or LM3445MM/NOPB equivalent, key selection criteria include TRIAC dim decoder compatibility, adaptive off-time control for ripple-current regulation, thermal shutdown at 165°C, VSSOP-10 package footprint, and FLTR2-based analog dimming interface.
Technical Context
The LM3445MM/NOPB implements a proprietary adaptive constant off-time control architecture that adjusts switching frequency inversely with input line voltage to maintain stable LED current under varying dimmer conduction angles. Its integrated angle-detect comparator (7.21 V threshold on BLDR) and ASNS-to-FLTR1 filtering decode TRIAC firing phase into a DC dimming reference.
It combines passive PFC via external valley-fill circuitry with internal bleeder MOSFET (230 Ω typical) to ensure reliable TRIAC triggering across load conditions. The GATE output drives an external N-channel MOSFET, while ISNS monitors peak current with 1.269 V (typ) threshold and 125 ns leading-edge blanking.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 80–277 VAC - supports global mains operation without input range switching. |
| LED Current Capability | >1 A - set externally via ISNS sense resistor; enables high-lumen LED strings. |
| Internal Ramp Frequency | 5.85 kHz - defines dim decoder resolution and sets minimum PWM on-time. |
| Bleeder Resistance | 230 Ω (typ) - ensures TRIAC holding current during low-conduction-angle dimming. |
| Thermal Shutdown | 165°C (typ), 20°C hysteresis - protects IC during overloads or poor heatsinking. |
| VCC UVLO Threshold | Rising: 7.7 V, Falling: 6.4 V - prevents erratic startup/shutdown during brownout. |
| ASNS Output Range | 0–4 V PWM - proportional to TRIAC on-time; feeds FLTR1 for dim decoding. |
Pinout & Package
LM3445MM/NOPB is housed in a 10-pin VSSOP (DGS) package, 3.00 mm × 3.00 mm body size, with exposed thermal pad (not electrically connected). Pin 1 is marked by dot; pin numbering follows standard counter-clockwise orientation from top-left corner.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 (COFF) | Constant Off-Time Set | Connects external RC network to define fixed off-time duration; determines switching frequency vs line voltage. |
| 2 (FLTR1) | Dim Decoder Input Filter | Receives filtered ASNS signal; tri-statable above 4.9 V to disable dimming for master/slave configurations. |
| 3 (FLTR2) | Analog Dim Reference | RC-filtered dim output (0–750 mV); sets LED current via PWM comparator reference. |
| 4 (ASNS) | TRIAC Angle Detection Output | 0–4 V PWM output proportional to dimmer conduction angle; feeds FLTR1 filter. |
| 5 (GND) | Power Ground | Reference node for ISNS, VCC, and internal comparators; must be low-impedance return path. |
| 6 (ISNS) | Current Sense Input | Monitors MOSFET source voltage; triggers current limit at 1.269 V (typ) with 125 ns blanking. |
| 7 (GATE) | MOSFET Driver Output | Push-pull gate driver (0.5 V saturation); directly drives external N-channel switch in buck stage. |
| 8 (VCC) | Internal Supply Rail | Regulated internal supply (8–12 V operating range); powers control logic and gate driver. |
| 9 (BLDR) | TRIAC Bleeder Control | Inputs rectified line voltage; activates internal 230 Ω bleeder below 7.21 V to sustain TRIAC firing. |
| 10 (DIM) | Multi-Function Dim Interface | I/O pin: accepts external PWM or outputs synchronized dim signal to other LM3445s in multi-string systems. |
Key Features
| Feature | Design Value |
|---|---|
| TRIAC Dim Decoder Circuit | Converts 45°–135° conduction angles into 0–100% smooth LED dimming without 120-Hz flicker. |
| Adaptive Constant Off-Time Control | Maintains constant LED current ripple across 80–277 VAC by dynamically adjusting switching frequency. |
| Integrated Bleeder Circuit | 230 Ω internal resistor ensures TRIAC remains latched during low-brightness operation without external components. |
| Valley-Fill PFC Support | Enables passive power factor correction >0.9 with external diode-capacitor networks; reduces VBUCK ripple. |
| Thermal Shutdown Protection | Auto-restarts at 145°C after shutdown at 165°C; prevents permanent damage during sustained overload. |
Applications
| Residential LED Retrofit Lamps | Commercial Downlight Modules |
|---|---|
|
Use Scenario: Replacing incandescent A19 bulbs in existing wall-dimmer-controlled fixtures. IC Role / Device Role: TRIAC-dimmable buck controller managing constant current for 7–14 series-connected LEDs. Use Value: Eliminates visible 120-Hz flicker and maintains smooth dimming down to 1% brightness using legacy dimmers. |
Use Scenario: Integrated LED downlights in office ceilings with centralized TRIAC dimming panels. IC Role / Device Role: Primary LED current controller enabling synchronized dimming across multiple luminaires via DIM pin daisy-chain. Use Value: Enables master/slave configuration without external microcontrollers; supports >1 A per channel with <2% current variation. |
| Industrial High-Bay Lighting | Smart Building Emergency Exit Signs |
|
Use Scenario: High-lumen LED arrays in warehouse high-bay fixtures powered from 277 VAC mains. IC Role / Device Role: Offline buck controller with extended input range (80–277 VAC) and robust thermal protection. Use Value: Delivers >1 A LED current with 90%+ efficiency at 277 VAC; thermal shutdown prevents failure in enclosed fixtures. |
Use Scenario: Dual-mode exit signs with battery backup and dimmable AC operation. IC Role / Device Role: Primary AC LED driver with FLTR2 analog dimming input for daylight harvesting integration. Use Value: Accepts 0–750 mV external dim signal (e.g., from photocell) to reduce power consumption during daytime. |
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 |
|---|---|---|---|
| ON Semiconductor NCL30000 | Fixed-frequency (50–500 kHz) CCM buck controller; requires external TRIAC decoder IC or MCU. | Lacks integrated dim decoder; needs additional components for phase-cut dimming support. | Choose when system already includes microcontroller or requires higher-frequency operation (>200 kHz). |
| Diodes Incorporated AL1676 | Single-stage flyback controller with integrated 650 V MOSFET; no external buck switch required. | Higher BOM cost per watt but eliminates external MOSFET, gate driver, and current sense resistor. | Prefer for compact, low-component-count designs where isolation and single-stage topology are acceptable. |
Compared with NCL30000 and AL1676, LM3445MM/NOPB uniquely integrates TRIAC angle detection, bleeder control, and adaptive off-time regulation in a 10-pin VSSOP - reducing external component count for non-isolated buck LED drivers while maintaining full dimmer compatibility.
Availability
LM3445MM/NOPB is available at Aetrix Electronics and suitable for residential LED retrofits, commercial downlights, and industrial high-bay lighting requiring stable component supply, long-term lifecycle support, and consistent dimming performance across global AC mains voltages.
Supply support for LM3445MM/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 LM3445 product line was engineered specifically for TRIAC-dimmable, non-isolated LED lighting applications - prioritizing flicker-free dimming, passive PFC integration, and seamless compatibility with legacy residential and commercial dimming infrastructure.
FAQ
What is the primary function of the BLDR pin on the LM3445MM/NOPB?
The BLDR pin on the LM3445MM/NOPB senses the rectified AC line voltage to detect TRIAC conduction state. It triggers the internal bleeder circuit (230 Ω) when voltage falls below 7.21 V, ensuring sufficient holding current for reliable TRIAC firing - a critical function for stable dimming performance across all brightness levels in the LM3445MM/NOPB design.
How does the LM3445MM/NOPB eliminate 120-Hz LED flicker?
The LM3445MM/NOPB eliminates 120-Hz flicker by decoupling dimming control from the rectified line frequency: its internal 5.85-kHz ramp generator and ASNS-to-FLTR1 filtering convert TRIAC phase angle into a stable DC reference (0–750 mV), which directly regulates LED current via the buck converter - independent of line-cycle variations. This architecture ensures continuous, ripple-free current delivery in every LM3445MM/NOPB implementation.
Can the LM3445MM/NOPB drive more than one LED string simultaneously?
Yes - the DIM pin on the LM3445MM/NOPB supports master/slave operation: one LM3445MM/NOPB configured as master can drive the DIM pins of multiple slave LM3445MM/NOPB controllers, synchronizing dimming across independent LED strings without external timing circuitry or microcontrollers - enabling scalable, multi-channel lighting systems using only the LM3445MM/NOPB's native interface.
What is the role of the COFF pin in LM3445MM/NOPB operation?
The COFF pin on the LM3445MM/NOPB sets the constant off-time duration for the adaptive buck controller. An external resistor and capacitor connected from GATE to COFF determine switching frequency - allowing designers to optimize efficiency, EMI, and inductor size for specific input voltage ranges and LED string configurations in each LM3445MM/NOPB application.
Does the LM3445MM/NOPB require an external MOSFET, and why?
Yes - the LM3445MM/NOPB is a controller-only IC and requires an external N-channel MOSFET driven by its GATE pin. This architecture allows designers to select MOSFETs optimized for voltage rating (e.g., 600 V), RDS(on), and thermal performance - enabling flexible, cost-effective, and efficient buck stage implementation across diverse LED loads and input voltages in every LM3445MM/NOPB design.
LM3445MM/NOPB Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- -
- Package/Case:
- 10-TFSOP, 10-MSOP (0.118", 3.00mm Width)
- Packaging:
- Tape & Reel (TR)
- 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:
- 10-VSSOP
LM3445MM/NOPB FAQ
1.How can I place an order for LM3445MM/NOPB through Aetrix?
Please submit a Request for Quotation (RFQ) for LM3445MM/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 LM3445MM/NOPB reliable?
The price and inventory of LM3445MM/NOPB are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LM3445MM/NOPB is usually 5 days.
3.What payment methods are accepted for LM3445MM/NOPB?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LM3445MM/NOPB transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LM3445MM/NOPB?
LM3445MM/NOPB orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LM3445MM/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 LM3445MM/NOPB?
For technical support, including LM3445MM/NOPB datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LM3445MM/NOPB requirements.
6.How does Aetrix verify that LM3445MM/NOPB is sourced from the original manufacturer or authorized distributors?
All LM3445MM/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 LM3445MM/NOPB meets industry standards.
7.What is the process for return or replacement of LM3445MM/NOPB?
All LM3445MM/NOPB units undergo pre-shipment inspection (PSI). If there is an issue with LM3445MM/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 LM3445MM/NOPB part is unused and in its original packaging.
Return procedure for LM3445MM/NOPB:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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