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Analog Devices Inc. LT3799IMSE#PBF
- Part No.:
- LT3799IMSE#PBF
- Manufacturer:
- Analog Devices Inc.
- Category:
- LED Drivers
- Package:
- 16-TFSOP (0.118", 3.00mm Width) Exposed Pad
- Datasheet:
-
LT3799IMSE#PBF.pdf
- Description:
- IC LED DRIVER OFFL TRIAC 16MSOP
- Quantity:
- Payment:
- Shipping:
Inventory:148
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Product details
Overview
LT3799IMSE#PBF from Analog Devices (formerly Linear Technology) is an isolated flyback LED controller with active power factor correction, designed for TRIAC-dimmable offline LED drivers. It delivers ±5% typical LED current regulation without opto-couplers, supports 90–270VAC input, achieves >0.97 power factor, and integrates a 1.9A gate driver for external high-voltage MOSFETs in 4W–100W+ lighting applications.
For engineers reviewing the LT3799IMSE#PBF datasheet, LT3799IMSE#PBF pinout, LT3799IMSE#PBF application, or LT3799IMSE#PBF equivalent, key selection considerations include critical conduction mode operation, primary-side current sensing architecture, VIN_SENSE-based PFC control, FAULT pin behavior for open/short LED detection, and thermal performance in the 16-lead MSOP package with exposed pad.
Technical Context
The LT3799IMSE#PBF implements a novel primary-side regulation scheme using DCM detection on a transformer third winding to infer secondary current-eliminating opto-couplers while maintaining ±5% LED current accuracy. Its multiplier-based PFC circuit modulates peak current limit proportionally to rectified line voltage, enabling >0.97 power factor across universal AC inputs.
Critical conduction mode (CrCM) operation is enforced via dv/dt detection on the DCM pin, synchronized to zero-current crossing of the secondary diode. The controller uses hysteretic start-up (23V turn-on, 12.3V turn-off), internal 10V LDO (INTVCC), and CT-pin-based fault timing with 240mV low threshold and 1.25V high threshold for reliable open/short LED protection.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| VIN Turn-On Voltage | 23 V - Enables startup from offline AC after rectification and bulk capacitor charging |
| Power Factor (Typical) | 0.97 - Achieved via VIN_SENSE-scaled multiplier controlling peak current limit |
| LED Current Accuracy | ±5% typical - Primary-side regulation without opto-coupler or secondary feedback |
| Gate Driver Output | 1.9 A - Drives high-voltage N-channel MOSFETs directly; VOL = 0.05 V, VOH = INTVCC – 0.05 V |
| Operating Temp Range | –40°C to 125°C - Validated junction temperature range for industrial and outdoor LED drivers |
| INTVCC Regulation | 10 V ±0.2 V - Internal LDO supplies gate driver and internal circuitry; dropout <1.15 V below VIN |
| Oscillator Frequency Range | 25 kHz to 300 kHz - Variable-frequency CrCM operation adapts to line/load conditions |
Pinout & Package
LT3799IMSE#PBF is housed in a thermally enhanced 16-lead plastic MSOP package (MSE) with exposed pad (Pin 17), requiring soldering to PCB for electrical grounding and thermal dissipation (θJA = 50°C/W, θJC = 10°C/W).
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| CTRL1/2/3 (1–3) | Current Set Input | Lowest applied voltage among three pins sets LED current reference; supports analog dimming and thermal compensation |
| VREF (4) | 2V Reference Output | Stable 2V source (±2.5% over temp) for resistor-divider programming of CTRL pins; drives ≤200 µA |
| FAULT (5) | Open/Short LED Indicator | Open-drain output pulled low when FB > 1.25V and CT > 1.25V - signals LED string failure |
| CT (6) | Fault Timing Control | Charged at 10 µA; switching enabled above 340 mV; fault recovery triggered below 240 mV |
| COMP+/COMP– (7–8) | Error Amplifier Compensation | Differential nodes for loop compensation capacitor (C6); set integrator gain and phase margin |
| FB (9) | Third-Winding Feedback | Samples reflected voltage during MOSFET off-time to detect open LED condition |
| DCM (10) | Discontinuous Mode Detection | Detects dv/dt on transformer third winding to identify zero-current crossing for CrCM timing |
| VIN (11) | Startup Supply Input | Accepts up to 32V; powers internal LDO and start-up circuit; includes 25V shunt regulator |
| GATE (14) | MOSFET Gate Driver | 1.9A push-pull output switching between INTVCC and GND; fast rise/fall times (<20 ns) |
| SENSE (15) | Primary Current Sense | Kelvin-connected to RSENSE to measure switch current; 100 mV threshold with ±4 mV tolerance |
| VIN_SENSE (16) | Line Voltage Sensing | Inputs scaled AC line voltage (1.25–1.5V at max input) for PFC multiplier function |
| GND (17) | Ground & Thermal Pad | Exposed pad must be soldered to PCB ground plane for EMI control and thermal management |
Key Features
| Feature | Design Value |
|---|---|
| No opto-coupler required | Primary-side regulation via DCM detection and third-winding sampling eliminates isolation barrier components and improves long-term reliability |
| TRIAC dimming compatibility | Internal logic maintains MOSFET conduction during TRIAC off-phase to prevent misfiring and ensure smooth dimming down to 5% |
| Active PFC with >0.97 PF | VIN_SENSE-driven multiplier dynamically adjusts peak current limit to match sinusoidal line voltage waveform |
| Integrated 1.9A gate driver | Direct drive capability reduces external BOM count and enables fast switching with minimal layout parasitics |
| Robust fault protection | Simultaneous open LED (via FB), shorted LED (via SENSE overcurrent), and thermal shutdown (junction-limited) with auto-retry via CT pin |
Applications
| Architectural LED Downlights | Industrial High-Bay Lighting |
|---|---|
Use Scenario: 40W–100W constant-current LED modules mounted in ceiling fixtures operating from 120/230VAC mains with 0–10V or TRIAC dimming. IC Role / Device Role / Timing Role: LT3799IMSE#PBF acts as isolated flyback controller performing primary-side current regulation, PFC, and TRIAC synchronization without opto-isolation. Use Value: Enables compact, high-efficiency (≥90%) designs meeting IEC 61000-3-2 Class C harmonic limits and ENERGY STAR requirements. | Use Scenario: 60W–150W high-lumen LED luminaires installed in warehouses and factories with wide input voltage range (90–305VAC) and surge immunity. IC Role / Device Role / Timing Role: LT3799IMSE#PBF provides stable LED current regulation under fluctuating line conditions while maintaining >0.97 power factor and thermal derating via CTRL3 NTC interface. Use Value: Eliminates need for secondary-side feedback components, reducing bill-of-materials cost and improving system MTBF by 35% versus opto-coupled solutions. |
| Outdoor Street Lighting | Commercial Retail Track Lighting |
Use Scenario: IP66-rated LED streetlights operating outdoors with ambient temperatures from –40°C to +85°C and subjected to lightning-induced surges. IC Role / Device Role / Timing Role: LT3799IMSE#PBF serves as the core controller managing CrCM flyback conversion, open/short LED fault detection, and brownout-safe startup via hysteretic VIN threshold. Use Value: Delivers consistent lumen output across temperature extremes and ensures fail-safe shutdown during LED string failure per UL 8750 requirements. | Use Scenario: Adjustable-track LED spotlights with smooth 1–100% TRIAC dimming in retail stores, requiring flicker-free operation and color consistency. IC Role / Device Role / Timing Role: LT3799IMSE#PBF executes precise current regulation synchronized to leading-edge TRIAC phase-cut waveforms using VIN_SENSE transient detection. Use Value: Achieves <0.5% RMS current ripple and eliminates audible noise in magnetic transformers, supporting DALI-2 interoperability via optional analog interface. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar isolated PFC LED controller applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| UCC28810DR | Fixed-frequency discontinuous conduction mode (DCM); no CrCM; requires opto-coupler for secondary regulation | Limited to lower-power applications (<30W); lacks native TRIAC dimming support and primary-side open-LED detection | Choose UCC28810DR only if fixed-frequency operation and opto-isolated feedback are acceptable trade-offs for cost-sensitive designs |
| NCP1654ADR2G | Single-stage PFC + quasi-resonant flyback controller; no integrated gate driver; requires external high-side driver | Supports higher power (>150W) but adds complexity; no built-in FAULT pin or CT-based fault retry logic | Select NCP1654ADR2G when designing >100W systems where single-stage topology and higher efficiency outweigh added component count |
Compared with UCC28810DR and NCP1654ADR2G, the LT3799IMSE#PBF uniquely combines CrCM operation, opto-coupler–free primary-side regulation, integrated 1.9A gate driver, and dedicated TRIAC dimming logic-enabling simpler, more robust 4W–100W designs with fewer external components and faster time-to-market.
Availability
LT3799IMSE#PBF is available at Aetrix Electronics and suitable for architectural lighting, industrial high-bay fixtures, outdoor streetlights, and commercial track lighting requiring stable component supply, long lifecycle support, and full compliance with IEC 61000-3-2 harmonic standards.
Supply support for LT3799IMSE#PBF 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
Analog Devices acquired Linear Technology in 2017 and maintains full product support, documentation, and manufacturing continuity for all Linear ICs including the LT3799 family.
The LT3799 product line was specifically developed for cost-effective, high-efficiency, TRIAC-dimmable isolated LED drivers targeting commercial and industrial lighting applications where reliability, PFC compliance, and simplified design are critical.
FAQ
What is the minimum input voltage required to start up the LT3799IMSE#PBF?
The LT3799IMSE#PBF features a micropower hysteretic start-up circuit with a nominal turn-on voltage of 23 V at the VIN pin. Startup occurs when VIN rises above this threshold and the internal INTVCC LDO reaches regulation at 10 V. The device remains operational down to 12.3 V (typical turn-off voltage), providing 10.7 V of hysteresis to accommodate bulk capacitor discharge between AC line cycles. This behavior is confirmed in the Absolute Maximum Ratings and Electrical Characteristics tables of the official LT3799 datasheet.
How does the LT3799IMSE#PBF achieve power factor correction without an opto-coupler?
The LT3799IMSE#PBF achieves active PFC through a proprietary multiplier circuit that scales the peak current limit in real time using the VIN_SENSE pin voltage-a resistor-divider representation of the rectified AC line. This forces input current to follow the sinusoidal shape of the input voltage, yielding >0.97 power factor. Regulation is maintained entirely on the primary side using DCM detection and third-winding sampling, eliminating the need for opto-couplers or secondary-side feedback components as documented in the Block Diagram and OPERATION sections of the LT3799 datasheet.
Can the LT3799IMSE#PBF support both 120VAC and 230VAC inputs in the same design?
Yes, the LT3799IMSE#PBF supports universal input operation from 90VAC to 270VAC. Its VIN_SENSE pin accepts a scalable voltage divider (1.25–1.5V at maximum input), and its CrCM architecture automatically adjusts switching frequency to maintain regulation across input ranges. Typical performance graphs (Figures G18–G20) confirm stable LED current and >0.95 power factor across both 120VAC and 230VAC configurations, making the LT3799IMSE#PBF suitable for globally deployed lighting products without hardware changes.
What protection features are integrated into the LT3799IMSE#PBF?
The LT3799IMSE#PBF integrates open LED protection (via FB pin monitoring), shorted LED protection (via SENSE pin overcurrent detection), thermal shutdown (junction-limited to 125°C), and auto-retry fault recovery (via CT pin timing). The FAULT pin asserts low during detected failures, and the controller halts switching until the CT capacitor discharges to 240 mV, then re-attempts startup. These protections are fully specified in the Absolute Maximum Ratings, Electrical Characteristics, and OPERATION sections of the LT3799 datasheet.
Is the LT3799IMSE#PBF pin-compatible with other members of the LT3799 family?
Yes, the LT3799IMSE#PBF shares identical pinout, package (16-lead MSOP), and electrical specifications with the LT3799EMSE#PBF and LT3799HMSE#PBF variants. The only difference is the guaranteed operating temperature range: LT3799IMSE#PBF is rated for –40°C to 125°C junction temperature, matching the Industrial grade specification. All functional blocks, pin functions, and timing characteristics remain identical across these variants as confirmed in the ORDER INFORMATION table of the LT3799 datasheet.
LT3799IMSE#PBF Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- -
- Package/Case:
- 16-TFSOP (0.118", 3.00mm Width) Exposed Pad
- Packaging:
- Tube
- Product Status:
- Active
- Type:
- AC DC Offline Switcher
- Topology:
- Flyback
- Internal Switch(s):
- No
- Number of Outputs:
- 1
- Voltage - Supply (Min):
- -
- Voltage - Supply (Max):
- -
- Voltage - Output:
- -
- Current - Output / Channel:
- -
- Frequency:
- 25kHz ~ 300kHz
- Dimming:
- Triac
- Applications:
- -
- Operating Temperature:
- -40°C ~ 125°C (TJ)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 16-MSOP-EP
LT3799IMSE#PBF FAQ
1.How can I place an order for LT3799IMSE#PBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LT3799IMSE#PBF 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 LT3799IMSE#PBF reliable?
The price and inventory of LT3799IMSE#PBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LT3799IMSE#PBF is usually 5 days.
3.What payment methods are accepted for LT3799IMSE#PBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LT3799IMSE#PBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LT3799IMSE#PBF?
LT3799IMSE#PBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LT3799IMSE#PBF 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 LT3799IMSE#PBF?
For technical support, including LT3799IMSE#PBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LT3799IMSE#PBF requirements.
6.How does Aetrix verify that LT3799IMSE#PBF is sourced from the original manufacturer or authorized distributors?
All LT3799IMSE#PBF 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 LT3799IMSE#PBF meets industry standards.
7.What is the process for return or replacement of LT3799IMSE#PBF?
All LT3799IMSE#PBF units undergo pre-shipment inspection (PSI). If there is an issue with LT3799IMSE#PBF, 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 LT3799IMSE#PBF part is unused and in its original packaging.
Return procedure for LT3799IMSE#PBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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