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Analog Devices Inc. LT3942JUFD#PBF
- Part No.:
- LT3942JUFD#PBF
- Manufacturer:
- Analog Devices Inc.
- Category:
- LED Drivers
- Package:
- 28-WFQFN Exposed Pad
- Datasheet:
-
LT3942JUFD#PBF.pdf
- Description:
- IC LED DRIVER RGLTR PWM 2A 28QFN
- Quantity:
- Payment:
- Shipping:
Inventory:190
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Product details
Overview
LT3942JUFD#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 peak switch current, operates at 300kHz–2MHz fixed or spread-spectrum frequency, and provides ±1.5% voltage regulation and ±3% current regulation for LED driver and voltage regulator applications in automotive lighting systems.
For engineers reviewing the LT3942JUFD#PBF datasheet, LT3942JUFD#PBF pinout, LT3942JUFD#PBF application, or LT3942JUFD#PBF equivalent, key selection criteria include its AEC-Q100 qualification, 28-lead QFN (4mm × 5mm) package with exposed thermal pad, seamless buck/buck-boost/boost mode transition, open/short LED fault detection with FAULT reporting, and support for 5000:1 external PWM dimming.
Technical Context
The LT3942JUFD#PBF implements a proprietary peak-buck/peak-boost current-mode control architecture 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 regulation supports simultaneous voltage feedback via FB and current sensing via ISP/ISN with programmable threshold via CTRL.
It integrates a 3.6V INTVCC linear regulator (±2% load regulation), 2.00V VREF reference (±1.5% accuracy), and dedicated pins for soft-start (SS), frequency setting (RT), synchronization/spread-spectrum (SYNC/SPRD), and PWM top-gate drive (PWMTG). Fault protection includes FB overvoltage (1.05V), open LED (VFB > 0.95V & V(ISP−ISN) < 10mV), and short LED (VFB < 0.25V) detection with latched or hiccup response.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 3V to 36V - supports wide-range industrial and automotive battery inputs including 12V, 24V, and 36V nominal systems. |
| Output Voltage Range | 0V to 36V - enables both step-down and step-up operation without external topology changes. |
| Switching Frequency | 300kHz to 2MHz - adjustable via RT resistor; synchronizable or spread-spectrum capable for EMI reduction. |
| Current Regulation Accuracy | ±3% - ensures precise LED string current control across temperature and line/load variations. |
| Voltage Regulation Accuracy | ±1.5% - maintains stable output under dynamic load and input conditions for sensitive analog or digital loads. |
| Peak Switch Current Limit | 2.5A - sets maximum inductor current during peak-buck or peak-boost modes for safe power delivery. |
| Operating Junction Temp | –40°C to +150°C - qualified per AEC-Q100 Grade 1, suitable for under-hood automotive environments. |
Pinout & Package
LT3942JUFD#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 package supports high-power density layout with low-inductance ground connection via soldered exposed pad.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| PVIN / VIN | Power input and bias supply rails | Dual-input capability: PVIN powers power stage; VIN supplies internal circuitry and INTVCC regulator - allows independent sourcing for noise isolation. |
| ISP / ISN | High-accuracy current sense differential inputs | Supports Kelvin-connected sense resistor for ±3% LED current regulation; common-mode range 0V–36V enables high-side or low-side placement. |
| FB | Voltage regulation feedback node | Regulates output to 1.00V reference; also enables open/short LED fault detection by monitoring VFB deviation thresholds. |
| PWMTG | High-side PMOS gate driver output | Drives external PMOS for PWM dimming with rail-to-rail swing (PVOUT − 5V to PVOUT); eliminates need for level-shifting circuitry. |
| FAULT | Open-drain fault status indicator | Pulled low on open LED (VFB > 0.95V & V(ISP−ISN) < 10mV) or short LED (VFB < 0.25V); requires external pull-up for system-level fault signaling. |
Key Features
| Feature | Design Value |
|---|---|
| 4-switch single-inductor buck-boost topology | Eliminates need for separate buck and boost converters; reduces BOM count, PCB area, and design complexity in multi-rail systems. |
| Flicker-free spread-spectrum modulation | 25% triangle dither above oscillator frequency reduces peak EMI by >10dB without compromising dimming performance. |
| 5000:1 external PWM dimming ratio | Enables ultra-fine brightness control in automotive headlamps and adaptive driving beam (ADB) systems without visible flicker. |
| AEC-Q100 Grade 1 qualification | Validated for automotive under-hood operation up to +150°C junction temperature with full parametric guarantee. |
| Integrated open/short LED fault reporting | Reduces system-level diagnostic overhead by providing direct FAULT pin assertion without microcontroller polling or ADC reads. |
Applications
| Automotive Adaptive Front Lighting | Industrial High-Bay LED Drivers |
|---|---|
Use Scenario: Dynamic beam shaping in ADB modules requiring precise, flicker-free dimming across multiple LED strings with varying forward voltages. IC Role / Device Role / Timing Role: Constant-current LED driver with 5000:1 PWM dimming, seamless buck-boost transition, and real-time open/short LED fault reporting. Use Value: Enables pixel-level illumination control while maintaining ASIL-B compatible diagnostics and meeting CISPR-25 Class 5 EMI limits. | Use Scenario: Wide-input industrial LED fixture powering 24–48V LED arrays from unregulated 24V–36V DC bus with variable load conditions. IC Role / Device Role / Timing Role: Synchronous buck-boost voltage regulator delivering stable 36V output with ±1.5% regulation and 93% efficiency at 2MHz switching. Use Value: Eliminates need for pre-regulator stages; supports compact heatsink-free designs in enclosed high-temperature enclosures. |
| Automotive Cabin Ambient Lighting | Medical Diagnostic Illumination |
Use Scenario: RGBW color-mixed interior lighting with independent current control per channel and synchronized dimming across multiple LT3942 units. IC Role / Device Role / Timing Role: Multi-channel constant-current LED driver with internal 128:1 PWM dimming and SYNC/SPRD pin for inter-device clock alignment. Use Value: Ensures zero phase offset between channels for smooth color transitions and eliminates beat frequencies in camera-captured scenes. | Use Scenario: High-stability surgical headlight requiring flicker-free, thermally compensated LED current with fault-safe shutdown. IC Role / Device Role / Timing Role: Precision current regulator with ±3% accuracy over –40°C to +150°C, open/short LED protection, and latch-off fault response. Use Value: Meets IEC 60601-1 creepage/clearance requirements via isolated sense path and guarantees fail-safe operation during critical procedures. |
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 FETs and gate drivers; wider input range (4V–36V). | Targeted at higher-power (>5A), discrete-layout designs where thermal management and efficiency optimization are prioritized over integration. | Select when board space is not constrained and peak efficiency >95% is required at >3A load; not drop-in compatible due to different pinout and control scheme. |
| MPQ4332GQ-AEC1-P | 3.5A integrated buck-boost; fixed 500kHz/1MHz frequency; no spread spectrum; only 1000:1 PWM dimming; no ISP/ISN differential sensing. | Suitable for cost-sensitive automotive interior lighting where full AEC-Q100 Grade 1 and ultra-high dimming ratio are not mandatory. | Choose for simpler BOM and lower unit cost in non-safety-critical ambient lighting; lacks LT3942JUFD#PBF's diagnostic granularity and EMI performance. |
Compared with LTC3789EUF#PBF and MPQ4332GQ-AEC1-P, the LT3942JUFD#PBF uniquely combines integrated 4-switch architecture, AEC-Q100 Grade 1 qualification, 5000:1 PWM dimming, and differential current sensing in a single 4mm × 5mm QFN - making it optimal for space-constrained, high-reliability automotive LED systems demanding comprehensive fault coverage and low EMI.
Availability
LT3942JUFD#PBF is available at Aetrix Electronics and suitable for automotive lighting, industrial LED drivers, and medical illumination systems requiring stable component supply, extended temperature operation, and long-term lifecycle continuity.
Supply support for LT3942JUFD#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. (ADI) is a global leader in high-performance analog, mixed-signal, and digital signal processing semiconductors, serving industrial, automotive, communications, and healthcare markets.
The LT3942JUFD#PBF belongs to ADI's Power by Linear™ family of high-efficiency DC/DC converters, engineered specifically for automotive-grade LED lighting and precision voltage regulation where reliability, thermal robustness, and diagnostic integrity are critical.
FAQ
What is the maximum operating junction temperature for the LT3942JUFD#PBF?
The LT3942JUFD#PBF is rated for continuous operation up to +150°C junction temperature and is AEC-Q100 Grade 1 qualified. This specification is guaranteed across the full –40°C to +150°C operating junction temperature range, with overtemperature protection engaging above this threshold to prevent permanent damage. The LT3942JUFD#PBF's thermal design supports under-hood automotive deployment without derating.
Does the LT3942JUFD#PBF support both constant-voltage and constant-current regulation simultaneously?
No - the LT3942JUFD#PBF operates in either constant-voltage mode (using FB feedback) or constant-current mode (using ISP/ISN sensing), selected by external configuration. In LED driver applications, current regulation is primary with voltage feedback used for fault detection; in voltage regulator mode, current monitoring serves as accurate input/output current limit. The LT3942JUFD#PBF does not regulate both parameters concurrently in closed loop.
How is PWM dimming implemented on the LT3942JUFD#PBF?
The LT3942JUFD#PBF supports two PWM dimming methods: external digital PWM (0V–>1.5V logic on PWM pin, up to 5000:1 ratio) and internal analog-controlled PWM (1V–2V on PWM pin with RP resistor setting frequency, up to 128:1 ratio). The PWMTG pin drives an external high-side PMOS switch, eliminating need for optocouplers or level shifters. Dimming is flicker-free due to synchronized current regulation and spread-spectrum operation.
What fault conditions trigger the FAULT pin on the LT3942JUFD#PBF?
The FAULT pin on the LT3942JUFD#PBF is pulled low during open LED (VFB > 0.95V and V(ISP−ISN) < 10mV) or short LED (VFB < 0.25V) conditions. Fault reporting occurs only during PWM high state and is latched during PWM low state. The LT3942JUFD#PBF also detects FB overvoltage (>1.05V), which disables all switches and PWMTG but does not assert FAULT.
Can the LT3942JUFD#PBF be synchronized to an external clock?
Yes - the LT3942JUFD#PBF supports external clock synchronization via the SYNC/SPRD pin. When driven with a clean CMOS clock signal between 300kHz and 2MHz, the internal oscillator locks to the external frequency with minimal jitter. This capability enables EMI reduction through frequency dithering or deterministic timing alignment across multiple LT3942JUFD#PBF units in multi-string LED systems.
LT3942JUFD#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 ~ 150°C (TJ)
- Grade:
- Automotive
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 28-QFN (4x5)
LT3942JUFD#PBF FAQ
1.How can I place an order for LT3942JUFD#PBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LT3942JUFD#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 LT3942JUFD#PBF reliable?
The price and inventory of LT3942JUFD#PBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LT3942JUFD#PBF is usually 5 days.
3.What payment methods are accepted for LT3942JUFD#PBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LT3942JUFD#PBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LT3942JUFD#PBF?
LT3942JUFD#PBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LT3942JUFD#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 LT3942JUFD#PBF?
For technical support, including LT3942JUFD#PBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LT3942JUFD#PBF requirements.
6.How does Aetrix verify that LT3942JUFD#PBF is sourced from the original manufacturer or authorized distributors?
All LT3942JUFD#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 LT3942JUFD#PBF meets industry standards.
7.What is the process for return or replacement of LT3942JUFD#PBF?
All LT3942JUFD#PBF units undergo pre-shipment inspection (PSI). If there is an issue with LT3942JUFD#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 LT3942JUFD#PBF part is unused and in its original packaging.
Return procedure for LT3942JUFD#PBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
LT3942JUFD#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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