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Texas Instruments LM3450AMT/NOPB
- Part No.:
- LM3450AMT/NOPB
- Manufacturer:
- Texas Instruments
- Category:
- LED Drivers
- Package:
- 16-TSSOP (0.173", 4.40mm Width)
- Datasheet:
-
LM3450AMT/NOPB.pdf
- Description:
- IC LED DRVR OFFL ANALOG 16TSSOP
- Quantity:
- Payment:
- Shipping:
Inventory:290
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Product details
Overview
LM3450AMT/NOPB from Texas Instruments is a critical conduction mode (CRM) power factor controller with integrated phase dimming decoder, designed for isolated flyback LED drivers in 10–100W dimmable SSL applications. It delivers active PFC with >0.95 power factor, 70:1 decoded PWM dimming output at 500Hz, and dynamic hold circuitry optimized for 120V/230V AC inputs above 15W/25W respectively.
For engineers reviewing the LM3450AMT/NOPB datasheet, LM3450AMT/NOPB pinout, LM3450AMT/NOPB application, or LM3450AMT/NOPB equivalent, this page provides verified technical context, real-world design meaning of key specs, validated pin functions, confirmed alternative options, and supply support for production-grade LED driver development.
Technical Context
The LM3450AMT/NOPB implements CRM PFC control using zero-crossing detection (ZCD) to terminate off-time and regulate output voltage while shaping sinusoidal input current. Its multiplier-based current loop accepts VAC (sampled rectified line) and COMP (error amplifier output) to generate variable peak-detect thresholds, enabling near-constant on-time and high PF across line cycles.
The phase dimming decoder samples VAC angle, applies dynamic filtering and programmable remapping, then outputs a smooth 500Hz PWM signal on DIM. Unlike the LM3450, the LM3450A variant features continuous dynamic hold current-ensuring reliable triac firing in high-power single-stage or large-capacitance two-stage designs without sampling gaps.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| VCC Operating Range | 8.5V to 20V - supports startup via BIAS pre-regulator and stable operation across bias supply variations in offline LED drivers. |
| PFC Mode | Critical Conduction Mode (CRM) - enables zero-current switching for high efficiency and low EMI in flyback/boost topologies. |
| DIM Output Frequency | 180–700 Hz (typ. 500 Hz) - provides standardized PWM dimming interface compatible with downstream LED driver ICs. |
| Dynamic Hold Type | Continuous - eliminates triac misfire risk in 120V >15W and 230V >25W applications, unlike sampled hold in LM3450. |
| Junction Temp Range | −40°C to +125°C - ensures reliability in enclosed luminaires and outdoor-rated fixtures with thermal derating. |
| Thermal Resistance θJA | 38.0°C/W (TSSOP-16) - requires PCB copper pour and thermal vias for >25W continuous dissipation in ambient >60°C. |
| FB Reference Voltage | 2.43–2.57 V - sets precise output voltage regulation point when used with external resistor divider in non-isolated designs. |
Pinout & Package
LM3450AMT/NOPB is housed in a 16-pin TSSOP package (Package Code: PW), thermally enhanced for surface-mount assembly in compact LED driver PCBs.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| 1 VREF | 3V Precision Reference Output | Provides stable 2.85–3.15V reference for VADJ biasing and external analog circuits; max 3mA load. |
| 2 VADJ | Analog Dimming & Range Adjustment | Configures dimming range (70% standard) or enables low-power mode (GND); 1µA pull-up supports resistor-divider scaling. |
| 3 FLT2 | Second-Order Filter Input | Connects to FLT1 capacitor and GND to form second pole in dimmer angle filter network for smooth transitions. |
| 4 FLT1 | First-Order Filter Input | Accepts RC network from VAC path to establish primary filter pole; defines dimmer response time and noise immunity. |
| 5 DIM | Open-Drain PWM Dim Output | Delivers 500Hz PWM signal directly or via optocoupler to secondary-side LED driver; 500kΩ standby impedance. |
| 6 VAC | Rectified AC Line Sampling Input | Accepts resistor-divided AC waveform (0–5.5V range) for angle detection; 500kΩ input impedance minimizes loading. |
| 7 COMP | Error Amplifier Output / PWM Comparator Input | Drives multiplier and PWM comparator; compensation capacitor to GND sets loop stability for PFC voltage regulation. |
| 8 FB | Inverting Feedback Input | Regulates output voltage to 2.5V reference; includes OVP shutdown (1.22×VFB) and short-circuit protection modes. |
| 9 ISEN | Input Current Sense Reference | Sets dynamic hold threshold (162–232mV) and enables hold current injection during dimmer conduction intervals. |
| 10 GND | Power Ground | Common return for all analog and power paths; must be low-impedance plane to minimize noise coupling into ZCD/CS. |
| 11 CS | Current Sense Input | Monitors MOSFET source voltage; 30mV comparator offset ensures zero-crossing current draw and distortion reduction. |
| 12 GATE | High-Current Gate Driver Output | Drives PFC MOSFET gate with ±1.5A peak; 2–8Ω pull-down resistance ensures fast turn-off and prevents shoot-through. |
| 13 VCC | Bias Supply Input | Accepts 8.5–20V primary bias; internal UVLO (12.2–13.6V enable, 7.4–8.5V disable) prevents erratic startup/shutdown. |
| 14 ZCD | Zero-Crossing Detection Input | Detects transformer demagnetization via 100kΩ resistor; 1.45–1.55V threshold with 150–250mV hysteresis rejects ringing. |
| 15 HOLD | Dynamic Hold Current Control | Drives external pass-FET gate to inject holding current; 22–42Ω on-resistance (RDSON-HD) scales with junction temperature. |
| 16 BIAS | Pre-regulator Gate Bias Output | Supplies gate drive to startup pass-FET; delivers 18.8–22.6V (low-power) or 13.5–14.5V (normal) depending on VCC state. |
Key Features
| Feature | Design Value |
|---|---|
| Critical Conduction Mode PFC | Enables >0.95 power factor with minimal input capacitance and reduced EMI filter size in 10–100W LED drivers. |
| 70:1 Phase Dimming Decoding | Maps triac firing angle to linear 500Hz PWM output, supporting full-range dimming compatibility with legacy wall dimmers. |
| Continuous Dynamic Hold Circuit | Eliminates triac misfire in high-power (>25W @ 230V) or large-input-capacitance designs by maintaining hold current at all times. |
| Programmable Dimming Range via VADJ | Extends usable dimming range beyond 70% using resistor divider from VREF, improving compatibility with low-angle dimmers. |
| Integrated Pre-regulator Bias (BIAS) | Reduces need for auxiliary winding or external LDO by generating startup gate bias directly from rectified AC line. |
Applications
| Dimmable Downlights & Troffers | Large-Form-Factor LED Bulbs |
|---|---|
|
Use Scenario: Commercial office ceiling troffer with TRIAC wall dimmer and isolated flyback driver stage. IC Role / Device Role / Timing Role: LM3450AMT/NOPB performs both CRM PFC and phase angle decoding, delivering regulated 48V output and 500Hz PWM to secondary LED driver. Use Value: Achieves >0.95 PF and flicker-free dimming down to 1%, eliminating compatibility issues with leading-edge dimmers in 230V/30W systems. |
Use Scenario: A19-style smart bulb requiring compact, thermally constrained driver with universal AC input. IC Role / Device Role / Timing Role: LM3450AMT/NOPB integrates PFC and dimming decode into single TSSOP-16 IC, reducing BOM count and board area. Use Value: Continuous dynamic hold ensures reliable dimmer operation without external hold circuitry, critical in space-limited bulb envelopes. |
| Outdoor Area Lighting | Industrial 2-Stage LED Drivers |
|
Use Scenario: Streetlight fixture operating at −40°C to +85°C ambient with 230V AC input and 60W LED load. IC Role / Device Role / Timing Role: LM3450AMT/NOPB regulates boost PFC stage and decodes phase dimming for DALI-compatible secondary control. Use Value: −40°C to +125°C junction rating and 38°C/W θJA allow stable operation with passive heatsinking in sealed outdoor enclosures. |
Use Scenario: High-efficiency industrial luminaire using separate PFC + LLC stages, where LM3450AMT/NOPB controls only the front-end PFC. IC Role / Device Role / Timing Role: LM3450AMT/NOPB manages critical-conduction-mode boost PFC while providing isolated feedback via optocoupler to secondary controller. Use Value: FB pin bypass mode (5.11kΩ to GND) disables internal error amplifier, enabling seamless integration with external secondary-side regulation. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar LED driver PFC and dimming decode applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LM3450MT/NOPB | Uses sampled (not continuous) dynamic hold current; lower quiescent power in <15W/120V or <25W/230V designs. | Suitable for low-power 2-stage drivers where hold current duty cycle can be minimized without misfire risk. | Select LM3450MT/NOPB only when power level and dimmer type permit intermittent hold activation. |
| UCC28051DR | Dedicated CRM PFC controller without integrated dimming decoder; requires external microcontroller or analog circuit for phase decode. | Used in non-dimmable or digitally controlled LED drivers where flexibility in dimming protocol (e.g., 0–10V, DALI) is required. | Choose UCC28051DR when dimming interface is not phase-based or when higher PFC precision is prioritized over integration. |
Compared with LM3450MT/NOPB, the LM3450AMT/NOPB trades slightly higher standby current for guaranteed triac hold in high-power applications; versus UCC28051DR, it sacrifices PFC-only optimization to deliver complete dimmable driver functionality in one IC.
Availability
LM3450AMT/NOPB is available at Aetrix Electronics and suitable for dimmable LED lighting, commercial troffers, and outdoor area SSL requiring stable component supply across extended product lifecycles.
Supply support for LM3450AMT/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 LED driver innovation.
The LM3450A product line targets cost-sensitive, high-volume dimmable LED drivers requiring integrated PFC and phase-dimming compatibility in compact form factors.
FAQ
What is the key functional difference between LM3450AMT/NOPB and LM3450MT/NOPB?
The LM3450AMT/NOPB implements continuous dynamic hold current, ensuring reliable triac dimmer operation in all conditions above 15W (120V) or 25W (230V). In contrast, the LM3450MT/NOPB samples hold current only during decoding intervals, making it suitable for lower-power applications where intermittent hold suffices. This distinction directly affects dimmer compatibility and system-level reliability in production LED drivers.
Can LM3450AMT/NOPB be used in non-isolated boost PFC topologies?
Yes, LM3450AMT/NOPB supports non-isolated boost configurations. The FB pin connects to an output voltage divider to close the PFC voltage loop, and the internal error amplifier regulates VFB to 2.5V. COMP compensation is configured externally, and ZCD is unused. The device maintains full phase-dimming decode functionality regardless of topology, making it viable for simpler, lower-cost boost-based LED drivers.
How does the LM3450AMT/NOPB handle over-voltage protection?
The LM3450AMT/NOPB provides over-voltage protection (OVP) through the FB pin: when VFB exceeds 1.22× its nominal 2.5V reference (≈3.05V), the device terminates switching and enters shutdown mode. This protects downstream LEDs and capacitors from overvoltage events. Recovery occurs only after VFB falls below the hysteresis threshold (150–186mV below trip point), ensuring stable re-start without oscillation.
What is the purpose of the BIAS pin on LM3450AMT/NOPB?
The BIAS pin on LM3450AMT/NOPB delivers a regulated gate drive voltage (13.5–14.5V normal, 18.8–22.6V low-power) to an external pass-FET during startup, enabling self-biased operation without auxiliary windings or external regulators. This reduces component count and improves reliability in compact LED driver designs where space and BOM cost are critical constraints.
Does LM3450AMT/NOPB support analog dimming in addition to phase dimming?
Yes, LM3450AMT/NOPB supports analog dimming via the VADJ pin: applying a DC voltage between 0V (low-power mode) and VREF (3V) adjusts the effective dimming range and mapping curve. When VADJ = VREF, standard 70% phase dimming range is enforced; intermediate voltages extend usable dimming depth for specific dimmer types, offering design flexibility beyond fixed PWM decoding.
LM3450AMT/NOPB Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Texas Instruments
- Series:
- -
- Package/Case:
- 16-TSSOP (0.173", 4.40mm Width)
- Packaging:
- Tube
- Product Status:
- Active
- Type:
- AC DC Offline Switcher
- Topology:
- Flyback, Step-Up (Boost)
- Internal Switch(s):
- Yes
- Number of Outputs:
- 1
- Voltage - Supply (Min):
- 8.5V
- Voltage - Supply (Max):
- 20V
- Voltage - Output:
- 11.5V
- Current - Output / Channel:
- -
- Frequency:
- -
- Dimming:
- Analog
- Applications:
- -
- Operating Temperature:
- -40°C ~ 125°C (TJ)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 16-TSSOP
LM3450AMT/NOPB FAQ
1.How can I place an order for LM3450AMT/NOPB through Aetrix?
Please submit a Request for Quotation (RFQ) for LM3450AMT/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 LM3450AMT/NOPB reliable?
The price and inventory of LM3450AMT/NOPB are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LM3450AMT/NOPB is usually 5 days.
3.What payment methods are accepted for LM3450AMT/NOPB?
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Note: Certain payment methods may incur a processing fee.
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LM3450AMT/NOPB orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LM3450AMT/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 LM3450AMT/NOPB?
For technical support, including LM3450AMT/NOPB datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LM3450AMT/NOPB requirements.
6.How does Aetrix verify that LM3450AMT/NOPB is sourced from the original manufacturer or authorized distributors?
All LM3450AMT/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 LM3450AMT/NOPB meets industry standards.
7.What is the process for return or replacement of LM3450AMT/NOPB?
All LM3450AMT/NOPB units undergo pre-shipment inspection (PSI). If there is an issue with LM3450AMT/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 LM3450AMT/NOPB part is unused and in its original packaging.
Return procedure for LM3450AMT/NOPB:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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