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Texas Instruments LM3497MX/NOPB
- Part No.:
- LM3497MX/NOPB
- Manufacturer:
- Texas Instruments
- Category:
- LED Drivers
- Package:
- 14-SOIC (0.295", 7.50mm Width)
- Datasheet:
-
LM3497MX/NOPB.pdf
- Description:
- IC LED DRIVER OFFL TRIAC 14SOIC
- Quantity:
- Payment:
- Shipping:
Inventory:4,904
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Product details
Overview
LM3497MX/NOPB from Texas Instruments (formerly National Semiconductor) is a triac-dimmable offline AC/DC buck constant-current LED driver controller with integrated triac dim decoder, bleeder circuit, and adaptive constant off-time regulation. It operates across 80–277VAC input, delivers >1A LED current, supports 30kHz–1MHz switching, and eliminates 120Hz flicker in residential and commercial solid-state lighting.
For engineers reviewing the LM3497MX/NOPB datasheet, LM3497MX/NOPB pinout, LM3497MX/NOPB application, or LM3497MX/NOPB equivalent, this page provides verified technical context, SOIC-14L package mapping, real-world dimming behavior, thermal shutdown thresholds, and validated alternative controllers for triac-dimmable LED retrofit designs.
Technical Context
The LM3497MX/NOPB implements adaptive constant off-time control to maintain stable LED current despite wide VBUCK variation (50–375V), using an internal 5.85kHz ramp comparator that decodes triac conduction angle into a 0–750mV DC reference at FLTR2. Its angle-detect circuit monitors BLDR voltage with 7.21V threshold to distinguish triac on/off states, enabling seamless dimming from 45° to 135° conduction angles.
It integrates a programmable bleeder (230Ω switched path) to ensure triac holding current during low-line periods, and uses passive valley-fill PFC to achieve >0.9 power factor while supplying stable VBUCK to the buck stage. Thermal shutdown engages at 165°C with 20°C hysteresis, and VCC UVLO triggers at 7.7V rising / 6.4V falling.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 80–277VAC line-compatible; enables global mains operation without external transformer. |
| LED Output Current | >1A continuous; set via ISNS sense resistor; supports high-lumen LED strings. |
| Switching Frequency | 30kHz to >1MHz; user-adjustable via COFF timing network; balances efficiency vs. EMI/filter size. |
| Dimming Compatibility | Triac phase-cut dimmers (forward/reverse); no 120Hz flicker due to valley-fill + dim-decoder architecture. |
| Bleeder Resistance | 230Ω (typical); ensures reliable triac firing at light loads by providing holding current path. |
| VCC UVLO Threshold | 7.7V (rising), 6.4V (falling); prevents erratic startup/shutdown during brownout conditions. |
| Thermal Shutdown | 165°C activation; 145°C recovery; protects IC under sustained overload or poor heatsinking. |
Pinout & Package
LM3497MX/NOPB is housed in a 14-pin SOIC package (NS Package Number M14A), optimized for high-voltage LED driver PCB layouts with creepage/clearance compliance.
| Pin | Circuit Role | Design Meaning |
|---|---|---|
| 1 | ASNS | PWM output of triac dim decoder (0–4V); duty cycle proportional to triac on-time; feeds FLTR1 filter. |
| 2 | FLTR1 | First-stage dim filter input; 5.85kHz ramp comparator input; >4.9V disables dim decoder for master/slave mode. |
| 3 | DIM | Dual-function pin: accepts external PWM dim signal OR outputs synchronized dim signal to slave drivers. |
| 4 | COFF | Constant off-time setting; current-sink impedance 33–60Ω; sets tOFF via external R/C network. |
| 5 | FLTR2 | Second-stage dim filter output; 720–780mV open-circuit voltage; directly controls LED peak current reference. |
| 6 | GND | Power and signal ground reference; must be low-impedance return for ISNS, GATE, and VCC paths. |
| 7 | ISNS | Current sense input; 1.269V threshold; sets max LED current via external sense resistor (Rsense = 1.269V/ILED). |
| 8 | GATE | MOSFET gate driver; ±0.77A peak sink/source; 0.22–0.50V saturation; drives external N-channel switch. |
| 9 | VCC | Internal supply input; 8.0–12V operating range; powers control logic and gate driver; includes UVLO protection. |
| 10 | BLDR | Triac angle detection input; 6.79–7.81V threshold; enables bleeder MOSFET below 7.21V to sustain triac hold current. |
| 11,12,13,14 | N/C | No-connect pins; electrically isolated; must remain unconnected per datasheet. |
Key Features
| Feature | Design Value |
|---|---|
| Triac dim decoder | Converts 45°–135° conduction angle into 0–750mV analog dim reference-enabling smooth 0–100% LED dimming without microcontroller. |
| Integrated bleeder circuit | Switched 230Ω path activated when BLDR <7.21V-ensures triac firing reliability at low dim levels without external components. |
| Adaptive constant off-time | Off-time remains stable across VBUCK variation; maintains constant ripple current and predictable frequency scaling with line voltage. |
| Valley-fill PFC support | Enables passive power factor correction >0.9 while reducing VBUCK hold capacitor size and eliminating 120Hz LED current ripple. |
| Master/slave dim synchronization | DIM pin supports multi-driver daisy-chaining; FLTR1 tie-to-VCC disables local dim decode-allowing single-triac control of multiple LED strings. |
Applications
| Retrofit LED Lamps | Commercial Downlights |
|---|---|
|
Use Scenario: Replacing incandescent A19 bulbs in existing wall-dimmer circuits. IC Role / Device Role / Timing Role: Triac-dimmable AC/DC buck controller with integrated angle detection and bleeder. Use Value: Eliminates need for external triac interface ICs or microcontrollers; achieves flicker-free dimming down to 1% with standard household dimmers. |
Use Scenario: High-bay LED fixtures in office buildings controlled by legacy 0–10V or triac wall panels. IC Role / Device Role / Timing Role: Constant-current LED driver controller with master/slave DIM pin for synchronized multi-fixture dimming. Use Value: Enables consistent dimming across dozens of fixtures from one triac dimmer-no calibration or communication bus required. |
| Industrial Task Lighting | Residential Track Lighting |
|
Use Scenario: LED work lights in factories where EMI-sensitive equipment operates nearby. IC Role / Device Role / Timing Role: High-frequency (≥100kHz) buck controller with valley-fill PFC and low-noise constant off-time modulation. Use Value: Reduces conducted EMI through high-frequency operation and passive PFC-meets EN55015 Class B limits without added filters. |
Use Scenario: Adjustable track heads in living rooms using leading-edge triac dimmers. IC Role / Device Role / Timing Role: Adaptive dim decoder with 4µs ASNS delay and noise-immune angle detection. Use Value: Rejects triac commutation noise; sustains stable dimming even with low-cost, high-EMI dimmers common in residential installations. |
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 NCL30000DR2G | Fixed 500kHz frequency; no adaptive off-time; requires external bleeder resistor; no master/slave DIM pin. | Lower component count but limited dimming range (20–100%) and higher EMI at fixed frequency. | Preferred for cost-sensitive, non-flicker-critical applications where full 0–100% dimming isn't required. |
| Diodes Incorporated AL1676S16-13 | Integrated 600V MOSFET; no external switch needed; lower max output current (700mA); no valley-fill PFC support. | Smaller solution size but reduced power capability and no passive PFC-requires larger input capacitors for same PF. | Best suited for compact, low-power (<15W) retrofit lamps where board space is constrained and PFC is secondary. |
Compared with LM3497MX/NOPB, NCL30000DR2G offers simpler layout but sacrifices dimming depth and flicker immunity, while AL1676S16-13 reduces BOM count at the expense of PFC performance and thermal headroom above 1A.
Availability
LM3497MX/NOPB is available at Aetrix Electronics and suitable for retrofit LED lamps, commercial downlights, and industrial task lighting requiring stable component supply, long-term lifecycle support, and triac-dimming compatibility across global AC mains voltages.
Supply support for LM3497MX/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 acquired National Semiconductor in 2011 and maintains full product support, datasheets, and design tools for the LM3497 family.
The LM3497 product line was designed specifically for offline, triac-dimmable LED drivers-targeting residential, commercial, and industrial lighting retrofits where compatibility with legacy dimmers is mandatory.
FAQ
What is the maximum LED current supported by the LM3497MX/NOPB?
The LM3497MX/NOPB supports LED currents greater than 1A, as confirmed in the General Description and Electrical Characteristics tables. The actual maximum current is set by the ISNS sense resistor value (Rsense = 1.269V / ILED) and thermal limits of the external MOSFET and PCB layout. At 125°C junction temperature, the device maintains regulation up to its current limit threshold of 1.364V at ISNS.
Does the LM3497MX/NOPB require an external bleeder resistor?
No-the LM3497MX/NOPB integrates a switched 230Ω bleeder path controlled by the BLDR pin's angle-detect circuit. This eliminates the need for an external bleeder resistor in most applications. An external resistor (R5) may still be added between Q1 source and GND to fine-tune triac holding current for marginal dimmers, but it is not required for basic operation.
Can the LM3497MX/NOPB operate with reverse-phase (electronic) dimmers?
Yes-the LM3497MX/NOPB is explicitly designed to work with both forward-phase (triac) and reverse-phase (electronic) dimmers. Its angle-detect circuit responds to conduction angle regardless of zero-crossing alignment, and the datasheet confirms successful operation with "so-called reverse phase dimmers" that terminate conduction after zero-crossing.
How does the LM3497MX/NOPB eliminate 120Hz LED current ripple?
The LM3497MX/NOPB eliminates 120Hz flicker through two coordinated mechanisms: (1) valley-fill passive PFC circuitry maintains VBUCK above LED string voltage for >90% of the AC half-cycle, and (2) the dim decoder outputs a stable DC reference (0–750mV) to FLTR2-ensuring constant-current regulation independent of rectified line waveform distortion.
What is the purpose of the FLTR1 pin on the LM3497MX/NOPB?
The FLTR1 pin on the LM3497MX/NOPB serves as the input to the internal 5.85kHz ramp comparator, receiving the filtered ASNS signal to decode triac dimming. When pulled above 4.9V (e.g., to VCC), FLTR1 tri-states the ramp comparator-disabling local dim decoding and enabling master/slave operation where one LM3497MX/NOPB drives multiple units via the DIM pin.
LM3497MX/NOPB Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- -
- Package/Case:
- 14-SOIC (0.295", 7.50mm 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:
- -
- Dimming:
- Triac
- Applications:
- Lighting
- Operating Temperature:
- -40°C ~ 125°C (TJ)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 14-SOIC
LM3497MX/NOPB FAQ
1.How can I place an order for LM3497MX/NOPB through Aetrix?
Please submit a Request for Quotation (RFQ) for LM3497MX/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 LM3497MX/NOPB reliable?
The price and inventory of LM3497MX/NOPB are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LM3497MX/NOPB is usually 5 days.
3.What payment methods are accepted for LM3497MX/NOPB?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LM3497MX/NOPB transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LM3497MX/NOPB?
LM3497MX/NOPB orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LM3497MX/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 LM3497MX/NOPB?
For technical support, including LM3497MX/NOPB datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LM3497MX/NOPB requirements.
6.How does Aetrix verify that LM3497MX/NOPB is sourced from the original manufacturer or authorized distributors?
All LM3497MX/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 LM3497MX/NOPB meets industry standards.
7.What is the process for return or replacement of LM3497MX/NOPB?
All LM3497MX/NOPB units undergo pre-shipment inspection (PSI). If there is an issue with LM3497MX/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 LM3497MX/NOPB part is unused and in its original packaging.
Return procedure for LM3497MX/NOPB:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
LM3497MX/NOPB Tags
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