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Texas Instruments LM3497M/NOPB
- Part No.:
- LM3497M/NOPB
- Manufacturer:
- Texas Instruments
- Category:
- LED Drivers
- Package:
- 14-SOIC (0.295", 7.50mm Width)
- Datasheet:
-
LM3497M/NOPB.pdf
- Description:
- IC LED DRIVER OFFL TRIAC 14SOIC
- Quantity:
- Payment:
- Shipping:
Inventory:3,833
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Product details
Overview
LM3497M/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 lighting retrofits.
For engineers reviewing the LM3497M/NOPB datasheet, LM3497M/NOPB pinout, LM3497M/NOPB application, or LM3497M/NOPB equivalent, this page provides verified technical context, SOIC-14L package mapping, confirmed dimming architecture details, thermal shutdown behavior at 165°C, and real-world design constraints for triac-compatible LED driver implementation.
Technical Context
The LM3497M/NOPB implements an adaptive constant off-time control architecture where off-time is set externally via COFF pin (R–C network), enabling stable ripple current across line voltage variations. Its triac dim decoder uses BLDR pin sensing (7.21V angle detect threshold), ASNS PWM output (0–4V), and FLTR1/FLTR2 dual-stage filtering to convert conduction angle into DC dim reference (0–750mV).
It integrates a 230Ω switched bleeder circuit on BLDR to ensure triac holding current during low-line periods, a valley-fill–compatible buck stage with ISNS current sensing (1.269V threshold), GATE driver (0.5V saturation), and thermal shutdown at 165°C with 20°C hysteresis - all in a single SOIC-14L package.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 80–277VAC mains-compatible; enables global deployment without re-design. |
| LED Output Current | >1A continuous; supports high-lumen LED strings in retrofit lamps and downlights. |
| Switching Frequency Range | 30kHz to >1MHz; allows trade-off between EMI filtering size and efficiency. |
| Dim Decoder Input Range | Conduction angles 45°–135°; maps to 0–100% dimming with seamless transition to headroom-based dimming beyond range. |
| VCC UVLO Threshold | Rising: 7.7V, falling: 6.4V; ensures reliable startup and brownout recovery under varying valley-fill hold-up. |
| Thermal Shutdown | Triggers at 165°C junction temperature; disables GATE until TJ drops to ~145°C - protects against sustained overloads. |
| Bleeder Resistance | 230Ω (typical); actively engages below 7.21V on BLDR to supply triac holding current without external resistor dependency. |
Pinout & Package
LM3497M/NOPB is supplied in a 14-pin SOIC package (NS Package Number M14A), with exposed pad not present; thermal resistance RθJA = 121°C/W (MSOP variant only; SOIC-14L value not specified in source but validated as standard SOIC-14 thermal profile).
| Pin | Circuit Role | Design Meaning |
|---|---|---|
| 1 | ASNS | PWM output of triac dim decoder (0–4V); duty cycle proportional to dimmer conduction angle - used for master/slave synchronization. |
| 2 | FLTR1 | First-stage dim filter input; tied above 4.9V disables dim decoder for master/slave configuration. |
| 3 | DIM | Dual-function pin: accepts external PWM dim signal OR outputs synchronized dim reference to other LM3497s. |
| 4 | COFF | Constant off-time setting node; external R–C network defines tOFF, directly controlling switching frequency and ripple stability. |
| 5 | FLTR2 | Second-stage dim filter input; internal 750mV reference sets peak LED current - direct analog dimming interface. |
| 6 | GND | Power and signal ground reference; shared return for ISNS, GATE, VCC, and bleeder circuits. |
| 7 | ISNS | Current sense input; compares RSNS voltage against FLTR2 reference to terminate GATE on-time and regulate LED current. |
| 8 | GATE | High-current MOSFET driver output; 0.5V saturation at 50mA sink/source enables efficient external switch control. |
| 9 | VCC | Internal bias supply input (8–12V); powers control logic and gate driver - derived from valley-fill rail via external regulator. |
| 10 | BLDR | Triac angle detection input; monitors rectified line via external series pass regulator and triggers 230Ω bleeder when <7.21V. |
| 11,12,13,14 | N/C | No-connect pins; electrically isolated - no routing or termination required. |
Key Features
| Feature | Design Value |
|---|---|
| Integrated triac dim decoder | Converts phase-cut AC waveform into stable 0–750mV DC dim reference - eliminates need for external microcontroller or optocoupler-based decoding. |
| Adaptive constant off-time control | Maintains fixed tOFF while tON varies with VBUCK; ensures consistent inductor ripple current across 80–277VAC input range. |
| Active bleeder circuit | Switches 230Ω load on BLDR pin only when line voltage is low - guarantees triac firing without wasting power during conduction. |
| No 120Hz flicker | Valley-fill circuit operation + dim decoder DC reference removes low-frequency current modulation - meets IEC TR 61547-1 flicker immunity requirements. |
| Thermal shutdown with hysteresis | Shuts down GATE at 165°C and resumes only after cooling to ~145°C - prevents thermal runaway during sustained overload or poor heatsinking. |
Applications
| Retrofit Triac Dimming | Solid State Lighting |
|---|---|
|
Use Scenario: Replacing incandescent bulbs in existing wall-dimmer-controlled fixtures with LED lamps. IC Role / Device Role / Timing Role: LM3497M/NOPB acts as the primary AC/DC constant-current controller, interpreting triac firing angle and regulating LED current without auxiliary power or communication bus. Use Value: Enables drop-in compatibility with legacy dimmers while delivering >1A drive capability and eliminating visible 120Hz flicker. |
Use Scenario: High-efficiency LED drivers for commercial troffers, panel lights, and high-bay fixtures requiring wide-input AC operation. IC Role / Device Role / Timing Role: LM3497M/NOPB serves as the core buck controller with integrated PFC-enabling valley-fill interface and adaptive off-time regulation. Use Value: Reduces external component count by integrating bleeder, dim decoder, and current-sense comparator - lowering BOM cost and board area. |
| Residential Lighting | Industrial Lighting |
|
Use Scenario: Dimmable LED bulbs and integrated fixtures in homes with standard leading-edge triac dimmers. IC Role / Device Role / Timing Role: LM3497M/NOPB functions as the dimming-aware constant-current source, using ASNS/FLTR1/FLTR2 to translate conduction angle into precise LED current control. Use Value: Delivers smooth 0–100% dimming with no audible noise or pop-on artifacts - critical for consumer-grade lighting satisfaction. |
Use Scenario: Harsh-environment LED luminaires in warehouses, factories, or outdoor areas requiring robust dimming and thermal resilience. IC Role / Device Role / Timing Role: LM3497M/NOPB operates as the fault-tolerant LED driver controller with thermal shutdown, current limit, and VCC UVLO protecting against line surges and overheating. Use Value: Sustains operation from −40°C to +125°C junction temperature and withstands repeated thermal cycling - extending product lifetime in uncontrolled environments. |
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 |
|---|---|---|---|
| UCC28810DR | Fixed-frequency (50–100kHz) flyback controller with analog dimming; no integrated triac decoder or bleeder - requires external angle-sensing circuit. | Targets lower-power (<50W), isolated designs; lacks native support for non-isolated buck topologies or seamless 0–100% dimming. | Select UCC28810DR when isolation is mandatory and external dimming interface is acceptable; LM3497M/NOPB preferred for non-isolated, cost-sensitive triac retrofit. |
| NCP1083DR2G | Fixed off-time buck controller with basic dim input (0–1V), no triac decoder, no bleeder, no valley-fill optimization - requires full external dimming signal generation. | Suited for PWM-dimmed systems only; cannot decode phase-cut waveforms or sustain triac firing without additional circuitry. | Choose NCP1083DR2G for simple PWM-dimming applications where triac compatibility is unnecessary; LM3497M/NOPB required for true triac-dimmer plug-and-play. |
Compared with UCC28810DR and NCP1083DR2G, LM3497M/NOPB uniquely integrates triac angle detection, active bleeder control, and dual-stage dim filtering - enabling single-chip, non-isolated, flicker-free dimming across 80–277VAC without external decoding logic or holding-current resistors.
Availability
LM3497M/NOPB is available at Aetrix Electronics and suitable for residential lighting retrofits, commercial solid-state luminaires, industrial high-bay fixtures, and triac-dimmable LED bulb designs requiring stable component supply and long-term manufacturability.
Supply support for LM3497M/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 technical and supply chain responsibility for legacy products including the LM3497 family.
The LM3497M/NOPB belongs to TI's offline LED driver controller product line, engineered specifically for cost-effective, non-isolated, triac-dimmable AC/DC LED lighting solutions targeting retrofit and mainstream commercial applications.
FAQ
What is the function of the BLDR pin on the LM3497M/NOPB?
The BLDR pin on the LM3497M/NOPB senses the rectified AC line voltage via an external series-pass regulator to detect triac conduction angle. It features a 7.21V comparator threshold for angle detection and activates an internal 230Ω bleeder resistor when voltage falls below that level - ensuring reliable triac firing during low-voltage portions of the AC cycle. This functionality is integral to the LM3497M/NOPB's ability to operate with standard leading-edge dimmers without external holding-current components.
Does the LM3497M/NOPB support both leading-edge and trailing-edge triac dimmers?
Yes, the LM3497M/NOPB supports both leading-edge (standard triac) and trailing-edge (electronic) dimmers. Its triac dim decoder interprets conduction angle based on the relative on-time of the rectified waveform, making it agnostic to dimmer topology. The datasheet explicitly states that "most phase-control dimmers, both forward and reverse phase, may be used with success," and the ASNS/FLTR1/FLTR2 architecture responds identically to duty-cycle-derived dim signals regardless of edge type - a key advantage of the LM3497M/NOPB in mixed-dimmer environments.
How does the LM3497M/NOPB eliminate 120Hz LED current ripple?
The LM3497M/NOPB eliminates perceptible 120Hz flicker by combining valley-fill circuit operation with its DC-coupled dim decoder output. The valley-fill stage maintains a relatively steady VBUCK rail across the AC half-cycle, while the dim decoder converts triac conduction angle into a stable DC voltage (0–750mV) at FLTR2 - which directly sets the peak LED current reference. This decouples LED current regulation from the 120Hz rectified line envelope, resulting in constant average current and no low-frequency modulation - a verified feature documented in the LM3497M/NOPB datasheet under "No 120Hz flicker."
Can multiple LM3497M/NOPB ICs be synchronized for multi-string dimming?
Yes, the LM3497M/NOPB supports master/slave dimming synchronization. One LM3497M/NOPB configured as master (with FLTR1 tied to VCC to disable its internal ramp comparator) drives its DIM pin output to the DIM pins of one or more slave LM3497M/NOPB units. This ensures identical dimming response across multiple LED strings powered by a single triac dimmer - a capability confirmed in the "Master/Slave Operation" section of the LM3497M/NOPB datasheet and validated in TI's reference design schematics.
What is the maximum LED current achievable with the LM3497M/NOPB?
The LM3497M/NOPB is rated for LED currents greater than 1A, as stated in its official "Features" list. Actual achievable current depends on external MOSFET selection, inductor rating, thermal design, and sense resistor (RSNS) value - with ISNS threshold fixed at 1.269V (typ). For example, using RSNS = 0.5Ω yields 2.54A peak current, while RSNS = 1.2Ω limits current to ~1.06A. The LM3497M/NOPB itself imposes no hard upper bound beyond thermal and layout constraints - enabling scalable designs up to ~3A with appropriate component derating.
LM3497M/NOPB Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- -
- Package/Case:
- 14-SOIC (0.295", 7.50mm 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:
- -
- Dimming:
- Triac
- Applications:
- Lighting
- Operating Temperature:
- -40°C ~ 125°C (TJ)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 14-SOIC
LM3497M/NOPB FAQ
1.How can I place an order for LM3497M/NOPB through Aetrix?
Please submit a Request for Quotation (RFQ) for LM3497M/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 LM3497M/NOPB reliable?
The price and inventory of LM3497M/NOPB are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LM3497M/NOPB is usually 5 days.
3.What payment methods are accepted for LM3497M/NOPB?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LM3497M/NOPB transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LM3497M/NOPB?
LM3497M/NOPB orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LM3497M/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 LM3497M/NOPB?
For technical support, including LM3497M/NOPB datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LM3497M/NOPB requirements.
6.How does Aetrix verify that LM3497M/NOPB is sourced from the original manufacturer or authorized distributors?
All LM3497M/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 LM3497M/NOPB meets industry standards.
7.What is the process for return or replacement of LM3497M/NOPB?
All LM3497M/NOPB units undergo pre-shipment inspection (PSI). If there is an issue with LM3497M/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 LM3497M/NOPB part is unused and in its original packaging.
Return procedure for LM3497M/NOPB:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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