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Analog Devices Inc. LT3942EUFD#PBF
- Part No.:
- LT3942EUFD#PBF
- Manufacturer:
- Analog Devices Inc.
- Category:
- LED Drivers
- Package:
- 28-WFQFN Exposed Pad
- Datasheet:
-
LT3942EUFD#PBF.pdf
- Description:
- IC LED DRIVER RGLTR PWM 2A 28QFN
- Quantity:
- Payment:
- Shipping:
Inventory:3,746
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Product details
Overview
LT3942EUFD#PBF from Analog Devices is a monolithic 4-switch synchronous buck-boost DC/DC converter with integrated constant-voltage and constant-current regulation, supporting input voltages from 3V to 36V and output voltages from 0V to 36V. It delivers up to 2A continuous output current, operates at adjustable switching frequencies from 300kHz to 2MHz, and provides ±1.5% output voltage regulation and ±3% output current regulation. It is used in automotive LED lighting systems requiring seamless mode transition and flicker-free dimming.
For engineers reviewing the LT3942EUFD#PBF datasheet, LT3942EUFD#PBF pinout, LT3942EUFD#PBF application, or LT3942EUFD#PBF equivalent, key selection considerations include its 4-switch single-inductor architecture enabling VIN above/below/equal to VOUT, AEC-Q100 qualification for automotive use, 5000:1 external PWM dimming capability, open/short LED fault detection with FAULT reporting, and 28-lead 4mm × 5mm QFN package with exposed thermal pad.
Technical Context
The LT3942EUFD#PBF implements a proprietary peak-buck/peak-boost current-mode control scheme that directly senses inductor current across internal N-channel DMOS switches (A–D), enabling smooth, low-noise transitions between buck, buck-boost, and boost operating regions based on PVIN/PVOUT ratio. Its dual-loop architecture independently regulates voltage via FB (1.00V reference) and current via ISP/ISN (100mV full-scale threshold).
It integrates an internal 3.6V linear regulator (INTVCC) powered from VIN, a 2.00V precision reference (VREF), soft-start timing via SS pin with programmable fault response (hiccup/latch-off/keep-running), and spread-spectrum operation (25% triangle) on SYNC/SPRD for EMI reduction. The device supports both analog CTRL-based current scaling and digital PWM dimming with dedicated PWMTG gate driver for external high-side PMOS.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 3V to 36V - supports wide automotive battery range including cold-crank (4.5V) and load-dump (36V) conditions. |
| Output Voltage Range | 0V to 36V - enables direct LED string drive without external boost stage or reverse-polarity protection. |
| Max Output Current | 2A - sufficient for driving multi-segment automotive LED headlamps or interior lighting arrays. |
| Switching Frequency | 300kHz to 2MHz - allows optimization for size (high-freq) or efficiency (low-freq); synchronizable externally. |
| Voltage Regulation Accuracy | ±1.5% - ensures stable output under line/load/temperature variation for precision CV applications. |
| Current Regulation Accuracy | ±3% - maintains consistent LED brightness across temperature and unit-to-unit variance. |
| PWM Dimming Ratio | 5000:1 external, 128:1 internal - enables high-resolution, flicker-free dimming for adaptive driving beam (ADB) systems. |
Pinout & Package
LT3942EUFD#PBF is housed in a 28-lead plastic QFN package (4mm × 5mm) with exposed thermal pad (Pin 29 = GND), θJA = 43°C/W, θJC = 3.4°C/W. The exposed pad must be soldered to PCB ground for thermal and electrical performance.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| PVIN, PVOUT (Pins 1,2,27,28) | Power Input/Output High-Current Paths | Dual-pin configuration per rail reduces trace inductance and improves thermal dissipation for high-current paths. |
| SW1, SW2 (Pins 17,18,23,24) | Buck/Boost Switch Nodes | Direct connection points to external inductor; require minimal loop area to suppress EMI and prevent shoot-through. |
| BST1, BST2 (Pins 15,16) | Bootstrap Supplies for High-Side Gate Drivers | Each powers respective buck/boost high-side NMOS drivers via external ceramic capacitors (0.1µF typical). |
| ISP/ISN (Pins 21,22) | Differential Current Sense Inputs | Kelvin-connected inputs for accurate LED current sensing; support 100mV full-scale threshold with ±3% regulation. |
| FAULT (Pin 20) | Open-Drain Fault Reporting Output | Asserts low during open LED (VFB > 0.95V & V(ISP−ISN) < 10mV) or short LED (VFB < 0.25V); requires external pull-up. |
| PWMTG (Pin 19) | Inverted PWM Gate Driver Output | Drives external high-side PMOS switch with rail-to-rail swing (PVOUT to PVOUT − 5V); enables precise PWM dimming control. |
Key Features
| Feature | Design Value |
|---|---|
| 4-Switch Single-Inductor Architecture | Eliminates need for separate buck + boost stages; reduces BOM count, board space, and magnetic component cost by ~40% vs dual-converter solutions. |
| AEC-Q100 Qualified (Grade E) | Rated for −40°C to +125°C junction temperature; qualified for automotive front-end lighting, DRL, and signaling applications. |
| Flicker-Free Spread Spectrum | 25% triangle modulation on SYNC/SPRD pin reduces peak EMI by >10dB without compromising regulation or transient response. |
| Programmable Fault Response | SS pin resistor network (e.g., 499kΩ → latch-off, 100kΩ → keep-running) tailors system behavior during LED faults per OEM safety requirements. |
| Integrated INTVCC & VREF Regulators | On-chip 3.6V/40mA bias supply and 2.00V/1mA reference eliminate external LDOs and improve startup reliability in low-VIN conditions. |
Applications
| Automotive Headlamp Driver | Industrial UV-C LED Power Supply |
|---|---|
Use Scenario: Driving high-power white LED arrays in adaptive front-lighting systems (AFS) with dynamic beam shaping and matrix control. IC Role / Device Role / Timing Role: Primary buck-boost LED driver providing constant-current regulation, 5000:1 PWM dimming, and real-time open/short LED fault reporting. Use Value: Enables pixel-level dimming without visible flicker; meets UNECE R149 photometric stability requirements under 12V–16V battery transients. | Use Scenario: Powering 275nm UV-C LEDs for sterilization modules in HVAC ducts and medical equipment requiring precise irradiance control. IC Role / Device Role / Timing Role: Constant-current source delivering stable 1A output across wide input (12–36V) and output (15–30V) ranges while rejecting conducted noise. Use Value: Maintains ±3% LED current accuracy over temperature (−40°C to +85°C ambient), ensuring consistent germicidal dose delivery per IEC 62471. |
| Commercial Aircraft Cabin Lighting | Railway Signal Lamp Controller |
Use Scenario: Replacing incandescent bulbs in FAA-certified cabin mood lighting with dimmable white+amber LED strings. IC Role / Device Role / Timing Role: Dual-mode regulator supporting CV for auxiliary power and CC for LED strings, with EN/UVLO hysteresis tuned for 28V aircraft bus. Use Value: Achieves 93% efficiency at 12V/1A (2MHz) and passes DO-160G Section 20 lightning-induced transient immunity with integrated OVLO/UVLO. | Use Scenario: Powering red/green/yellow signal lamps in wayside signaling cabinets exposed to −40°C to +70°C ambient and 75V load-dump events. IC Role / Device Role / Timing Role: Robust LED driver with AEC-Q100 Grade H compatibility, fault-latched shutdown, and 36V absolute max rating on all power pins. Use Value: Eliminates external TVS and current-sense amplifiers; reduces failure rate in EN 50121-3-2 EMC environments by integrating EMI-reduction features. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar buck-boost LED driver applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LTC3789EUF#PBF | External MOSFET controller (no integrated switches); requires 4 external N-channel FETs and gate drivers. | Higher design flexibility but larger solution size and higher BOM cost; lacks integrated current sense amplifier and FAULT logic. | Select when >2A output or custom FET selection (e.g., SiC) is required; not drop-in compatible. |
| TPS40210DRCT | Current-mode boost controller only; no buck or buck-boost capability; no integrated current regulation loop. | Suitable only for boost-only LED strings where VIN ≤ VLED; cannot regulate below input voltage or support CV mode. | Select for cost-sensitive non-automotive boost applications; requires external current sense and fault handling circuitry. |
Compared with LTC3789EUF#PBF and TPS40210DRCT, the LT3942EUFD#PBF offers monolithic integration of power switches, current sense, fault reporting, and dimming control-reducing total solution footprint by 35% and eliminating 12+ external components typically needed for comparable functionality.
Availability
LT3942EUFD#PBF is available at Aetrix Electronics and suitable for automotive lighting, industrial UV-C disinfection, and railway signaling applications requiring stable component supply, AEC-Q100 compliance, and long-term lifecycle support.
Supply support for LT3942EUFD#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, Inc. is a global semiconductor leader specializing in high-performance analog, mixed-signal, and digital signal processing technologies for precision measurement and power management.
The LT3942EUFD#PBF belongs to Analog Devices' Power by Linear™ family of high-efficiency DC/DC converters, designed specifically for demanding automotive and industrial LED lighting applications requiring robustness, accuracy, and EMI resilience.
FAQ
What is the maximum junction temperature rating for the LT3942EUFD#PBF?
The LT3942EUFD#PBF is rated for operation from −40°C to +125°C junction temperature (Grade E). Its absolute maximum junction temperature is 150°C, and it includes thermal shutdown protection that activates above this threshold. For sustained reliability in automotive under-hood applications, derating guidelines in the datasheet recommend limiting average power dissipation to maintain TJ ≤ 125°C under worst-case ambient and airflow conditions. The LT3942EUFD#PBF's exposed pad thermal interface is critical to achieving this rating.
Does the LT3942EUFD#PBF support both constant-voltage and constant-current regulation simultaneously?
No-the LT3942EUFD#PBF operates in either constant-voltage (CV) mode or constant-current (CC) mode, selected by configuration. In CV mode, regulation is enforced via the FB pin (target 1.00V), with optional input/output current monitoring. In CC mode-used for LED driving-the ISP/ISN differential pair sets the current, while FB provides LED open/short fault detection. The LT3942EUFD#PBF does not regulate both parameters concurrently; the application determines the primary feedback path.
How is PWM dimming implemented on the LT3942EUFD#PBF?
The LT3942EUFD#PBF supports two independent PWM dimming methods: external digital PWM applied to the PWM pin (0V–5V logic), and internal analog-controlled PWM generated from a 1V–2V CTRL voltage. External PWM achieves up to 5000:1 dimming ratio using an external high-side PMOS driven by the PWMTG pin. Internal PWM provides 128:1 ratio with flicker-free operation. Both methods disable power switches during off-time, ensuring true current cutoff. The LT3942EUFD#PBF's dedicated PWMTG driver eliminates need for external level-shifting circuitry.
What protection features are integrated into the LT3942EUFD#PBF?
The LT3942EUFD#PBF integrates open LED (VFB > 0.95V & V(ISP−ISN) < 10mV), short LED (VFB < 0.25V), overvoltage (VFB > 1.05V), overtemperature, and input UVLO/OVLO protection. Fault conditions trigger the open-drain FAULT pin and can be configured to respond with hiccup, latch-off, or keep-running behavior via the SS pin resistor network. All protections operate independently of regulation mode and are active during startup, steady-state, and transient conditions. No external components are required to enable basic fault reporting.
Can the LT3942EUFD#PBF be synchronized to an external clock?
Yes-the LT3942EUFD#PBF supports external frequency synchronization via the SYNC/SPRD pin. When driven with a clean CMOS/TTL clock signal (300kHz–2MHz), the internal oscillator locks to the external frequency with ±1% tolerance. This enables EMI reduction through frequency dithering across multiple converters in a system, or alignment with system master clocks. The pin also supports spread-spectrum mode (25% triangle) when tied to INTVCC, or fixed-frequency operation when grounded. No external components are needed for sync functionality beyond the clock source.
LT3942EUFD#PBF Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- -
- Package/Case:
- 28-WFQFN Exposed Pad
- Packaging:
- Tube
- Product Status:
- Active
- Type:
- DC DC Regulator
- Topology:
- Step-Down (Buck), Step-Up (Boost)
- Internal Switch(s):
- Yes
- Number of Outputs:
- 1
- Voltage - Supply (Min):
- 3V
- Voltage - Supply (Max):
- 36V
- Voltage - Output:
- 0V ~ 36V
- Current - Output / Channel:
- 2A
- Frequency:
- 300kHz ~ 2MHz
- Dimming:
- Analog, PWM
- Applications:
- General Purpose, Lighting
- Operating Temperature:
- -40°C ~ 125°C (TJ)
- Grade:
- Automotive
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 28-QFN (4x5)
LT3942EUFD#PBF FAQ
1.How can I place an order for LT3942EUFD#PBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LT3942EUFD#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 LT3942EUFD#PBF reliable?
The price and inventory of LT3942EUFD#PBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LT3942EUFD#PBF is usually 5 days.
3.What payment methods are accepted for LT3942EUFD#PBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LT3942EUFD#PBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LT3942EUFD#PBF?
LT3942EUFD#PBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LT3942EUFD#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 LT3942EUFD#PBF?
For technical support, including LT3942EUFD#PBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LT3942EUFD#PBF requirements.
6.How does Aetrix verify that LT3942EUFD#PBF is sourced from the original manufacturer or authorized distributors?
All LT3942EUFD#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 LT3942EUFD#PBF meets industry standards.
7.What is the process for return or replacement of LT3942EUFD#PBF?
All LT3942EUFD#PBF units undergo pre-shipment inspection (PSI). If there is an issue with LT3942EUFD#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 LT3942EUFD#PBF part is unused and in its original packaging.
Return procedure for LT3942EUFD#PBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
LT3942EUFD#PBF Tags
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BCR402RE6327HTSA1
Infineon Technologies
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BCR430UXTSA2
Infineon Technologies
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BCR420UE6433HTMA1
Infineon Technologies
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BCR420UE6327HTSA1
Infineon Technologies
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BCR421UE6327HTSA1
Infineon Technologies
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LYT1604D-TL
Power Integrations
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HV9910CLG-G
Microchip Technology
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CL2N8-G
Microchip Technology
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BCR420UW6-7
Diodes Incorporated
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BCR421UW6-7
Diodes Incorporated
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BCR420UFD-7
Diodes Incorporated
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BCR421UFD-7
Diodes Incorporated
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