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Analog Devices Inc. LT3942HUFD#PBF
- Part No.:
- LT3942HUFD#PBF
- Manufacturer:
- Analog Devices Inc.
- Category:
- LED Drivers
- Package:
- 28-WFQFN Exposed Pad
- Datasheet:
-
LT3942HUFD#PBF.pdf
- Description:
- IC LED DRIVER RGLTR PWM 2A 28QFN
- Quantity:
- Payment:
- Shipping:
Inventory:1,368
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Product details
Overview
LT3942HUFD#PBF from Analog Devices is a monolithic 4-switch synchronous buck-boost DC/DC converter with integrated constant-voltage and constant-current regulation, supporting both voltage regulator and high-precision LED driver applications. It operates across 3V–36V input and 0V–36V output, delivers up to 2A peak switch current, achieves ±1.5% output voltage regulation and ±3% output current regulation, and supports seamless mode transition in buck, buck-boost, and boost regions - used in automotive lighting systems requiring wide VIN/VOUT flexibility and flicker-free dimming.
For engineers reviewing the LT3942HUFD#PBF datasheet, LT3942HUFD#PBF pinout, LT3942HUFD#PBF application, or LT3942HUFD#PBF equivalent, key selection considerations include its AEC-Q100 qualification for automotive use, 300kHz–2MHz programmable switching frequency with spread spectrum EMI reduction, 5000:1 external PWM dimming capability, and dual ISP/ISN current-sense architecture enabling accurate LED current control down to 3mV sense threshold.
Technical Context
The LT3942HUFD#PBF implements Analog Devices' proprietary peak-buck/peak-boost current mode control, directly sensing inductor current through internal N-channel DMOS switches (A–D) to enable smooth transitions between buck, buck-boost, and boost operating regions without audible noise or regulation discontinuity. Its dual-loop architecture independently regulates FB (voltage loop, 1.00V reference) and ISP/ISN (current loop, 3–103mV programmable threshold), with VC serving as shared error amplifier output for both loops.
It integrates a 3.65V INTVCC linear regulator (±2% load regulation), 2.00V VREF reference (±1.5% accuracy), and dedicated fault logic that monitors open LED (FB > 0.95V & V(ISP−ISN) < 10mV), short LED (FB < 0.25V), and overvoltage (FB > 1.05V) conditions - all reported via open-drain FAULT pin with latch/hiccup/keep-running modes configurable via SS pin resistor.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 3V to 36V - supports automotive battery transients (cold crank, load dump) and industrial 24V rail operation without external pre-regulation. |
| Output Voltage Range | 0V to 36V - enables direct drive of multi-LED strings (e.g., 12V, 24V, 36V) or variable-output voltage regulation with no polarity reversal. |
| Switching Frequency | 300kHz to 2MHz - adjustable via RT resistor; allows optimization for size (high-freq) or efficiency (low-freq), with external sync or 25% triangle spread spectrum for EMI compliance. |
| Current Regulation Accuracy | ±3% - verified over full –40°C to +150°C junction temperature range, critical for consistent LED brightness in under-hood lighting. |
| Output Voltage Regulation | ±1.5% - tight tolerance maintained across line, load, and temperature, suitable for precision voltage rails in ADAS camera modules. |
| Peak Switch Current Limit | 2.2A to 2.8A - programmable hysteresis and thermal foldback protect against overload while sustaining 2A continuous LED current at 12V output. |
| Dimming Ratio | 5000:1 external PWM / 128:1 internal analog - enables ultra-low-level illumination (e.g., dashboard night mode) without color shift or low-frequency flicker. |
Pinout & Package
LT3942HUFD#PBF is housed in a 28-lead (4mm × 5mm) plastic QFN package with exposed GND pad (Pin 29), θJA = 43°C/W, rated for –40°C to +150°C junction temperature. The package supports automotive reliability requirements and requires soldering of the exposed pad to PCB ground plane for thermal and electrical integrity.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| PVIN, VIN | Power Input & Bias Supply | PVIN connects to main power rail; VIN powers internal circuitry and INTVCC regulator - decoupling required on both pins for stable gate drive and control logic. |
| ISP / ISN | Current Sense Differential Inputs | Kelvin-connected inputs for high-side or low-side current-sense resistor; support 3mV–103mV full-scale range with ±3% regulation accuracy. |
| FB | Voltage Feedback Input | Regulates output voltage to 1.00V reference; also enables open/short LED fault detection by monitoring VFB thresholds (0.25V/0.95V). |
| CTRL | Current Threshold Programming | Analog input setting ISP/ISN regulation point (0–100mV); 0.25V–1.15V gives linear scaling, ≥1.35V locks at full scale - enables dynamic current adjustment. |
| PWMTG | High-Side PMOS Gate Driver Output | Drives external high-side PMOS switch with rail-to-rail swing (PVOUT to PVOUT–5V); enables true high-side PWM dimming without shoot-through risk. |
| FAULT | Open-Drain Fault Reporting | Pulled low during open LED, short LED, or overvoltage; latched per SS configuration - provides fail-safe status for ASIL-B system monitoring. |
Key Features
| Feature | Design Value |
|---|---|
| 4-Switch Single-Inductor Architecture | Eliminates need for separate buck/boost ICs or complex multi-phase designs - reduces BOM count and PCB area in space-constrained automotive ECUs. |
| AEC-Q100 Qualified (H-grade) | Guaranteed operation from –40°C to +150°C junction temperature with full electrical characterization - meets automotive powertrain and lighting reliability standards. |
| Flicker-Free Spread Spectrum | 25% triangle modulation above base frequency reduces peak EMI by >10dB - simplifies CISPR 25 Class 5 compliance without added shielding or filters. |
| Dual-Loop Regulation (CV + CC) | Simultaneous FB-based voltage regulation and ISP/ISN-based current regulation - enables single IC to serve as both power supply and LED driver in adaptive front-lighting systems. |
| Programmable Fault Response | SS pin resistor selects hiccup (no resistor), latch-off (499kΩ), or keep-running (100kΩ) behavior during LED faults - supports functional safety requirements per ISO 26262. |
Applications
| Automotive Adaptive Front Lighting | Industrial Machine Vision Illumination |
|---|---|
Use Scenario: High-beam assist and cornering lights requiring dynamic current control across varying forward voltages (e.g., 12V–32V LED arrays). IC Role / Device Role / Timing Role: Constant-current LED driver with 5000:1 PWM dimming and seamless buck-boost transition during vehicle battery voltage sag. Use Value: Maintains consistent lumen output and color point across 8V–16V input transients while meeting UNECE R149 photometric tolerances. | Use Scenario: Stroboscopic LED flash for high-speed inspection cameras needing precise microsecond-level timing and repeatable intensity. IC Role / Device Role / Timing Role: Synchronized voltage regulator and current source, triggered via external SYNC signal to align LED pulses with camera shutter. Use Value: Enables sub-1µs jitter-free strobe control with <±3% current stability - critical for defect detection in semiconductor wafer inspection. |
| Automotive Interior Ambient Lighting | Medical Diagnostic Equipment Power |
Use Scenario: RGBW cabin lighting with independent channel dimming and thermal derating compensation. IC Role / Device Role / Timing Role: Multi-channel constant-current controller using CTRL pin analog programming to adjust per-channel current setpoints. Use Value: Achieves <0.1% relative intensity drift across –40°C to +85°C ambient, preserving calibrated color mixing in infotainment backlighting. | Use Scenario: Precision power supply for optical sensors and laser diodes in portable ultrasound devices. IC Role / Device Role / Timing Role: Low-noise CV/CC regulator delivering stable 5V/3.3V rails and 100mA–1A programmable current with <10mVpp ripple. Use Value: Reduces sensor readout noise floor by 12dB versus standard buck converters - improves SNR in Doppler signal processing. |
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 | Requires external MOSFETs; no integrated current regulation; only CV mode; no ISP/ISN interface or FAULT reporting. | Suitable for generic voltage regulation only - cannot replace LT3942HUFD#PBF in LED driver roles requiring CC dimming or fault diagnostics. | Select only when discrete FET control, higher efficiency at >3A, or custom loop compensation is required - not a drop-in replacement. |
| TPS63070DDCR | Single-inductor buck-boost but no current regulation; max 2.4A switch current; no PWM dimming support; only FB feedback; no AEC-Q100 rating. | Applicable for non-automotive consumer power rails where LED driving or functional safety is not needed. | Choose for cost-sensitive industrial power supplies with fixed 3.3V/5V outputs - lacks CC accuracy, dimming, and automotive qualification of LT3942HUFD#PBF. |
Compared with LTC3789EUF#PBF and TPS63070DDCR, the LT3942HUFD#PBF uniquely integrates dual-loop CV/CC regulation, AEC-Q100 H-grade qualification, and diagnostic FAULT signaling - making it the only option among the three qualified for ASIL-B automotive LED lighting systems requiring certified reliability and real-time fault response.
Availability
LT3942HUFD#PBF is available at Aetrix Electronics and suitable for automotive lighting, industrial machine vision, medical diagnostic equipment, and adaptive driver assistance systems requiring stable component supply across extended temperature and long product lifecycles.
Supply support for LT3942HUFD#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, founded in 1965 and headquartered in Wilmington, MA.
The LT3942HUFD#PBF belongs to ADI's Power by Linear™ family of high-reliability DC/DC converters, engineered specifically for demanding automotive and industrial applications requiring wide input ranges, precise current regulation, and robust fault handling.
FAQ
What is the maximum junction temperature specification for the LT3942HUFD#PBF?
The LT3942HUFD#PBF is rated for operation from –40°C to +150°C junction temperature and is guaranteed over this full range per AEC-Q100 Grade H qualification. Thermal shutdown activates above 150°C, and continuous operation beyond the absolute maximum rating may impair reliability. The exposed pad must be soldered to a thermally robust PCB ground plane to maintain θJA = 43°C/W.
Does the LT3942HUFD#PBF support both buck and boost configurations simultaneously?
Yes - the LT3942HUFD#PBF uses a 4-switch single-inductor topology that automatically transitions between buck, buck-boost, and boost regions based on the PVIN/PVOUT ratio. It does not require manual mode selection or external circuit reconfiguration. Seamless transitions occur across all three regions with low-noise, flicker-free operation verified in typical applications at 2MHz switching frequency.
How is LED open-circuit fault detected by the LT3942HUFD#PBF?
The LT3942HUFD#PBF detects open LED faults when FB voltage exceeds 0.95V *and* V(ISP−ISN) falls below 10mV - indicating loss of current path while output voltage rises. This condition pulls the open-drain FAULT pin low. Fault response (hiccup, latch-off, or keep-running) is configured via resistor value on the SS pin, enabling compliance with automotive functional safety requirements.
Can the LT3942HUFD#PBF be used as a pure voltage regulator without LED driver functionality?
Yes - the LT3942HUFD#PBF operates as a precision constant-voltage regulator when ISP/ISN are tied together or unused. In this mode, it regulates VOUT via the FB pin to 1.00V (scaled by external resistor divider), provides input/output current monitoring via ISMON, and retains all protection features including OVLO, UVLO, and thermal shutdown. The PWM pin controls an optional high-side PMOS load switch.
What is the purpose of the RP pin on the LT3942HUFD#PBF?
The RP pin sets the internal PWM dimming frequency when used in analog-dimming mode. A resistor to ground (28.7kΩ–332kΩ) programs frequencies from 256Hz to 16.4kHz. For external digital PWM dimming or voltage regulation, RP must be tied to ground. Leaving RP floating is prohibited - it must be actively terminated to ensure predictable dimming behavior and avoid undefined current regulation.
LT3942HUFD#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)
LT3942HUFD#PBF FAQ
1.How can I place an order for LT3942HUFD#PBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LT3942HUFD#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 LT3942HUFD#PBF reliable?
The price and inventory of LT3942HUFD#PBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LT3942HUFD#PBF is usually 5 days.
3.What payment methods are accepted for LT3942HUFD#PBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LT3942HUFD#PBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LT3942HUFD#PBF?
LT3942HUFD#PBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LT3942HUFD#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 LT3942HUFD#PBF?
For technical support, including LT3942HUFD#PBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LT3942HUFD#PBF requirements.
6.How does Aetrix verify that LT3942HUFD#PBF is sourced from the original manufacturer or authorized distributors?
All LT3942HUFD#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 LT3942HUFD#PBF meets industry standards.
7.What is the process for return or replacement of LT3942HUFD#PBF?
All LT3942HUFD#PBF units undergo pre-shipment inspection (PSI). If there is an issue with LT3942HUFD#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 LT3942HUFD#PBF part is unused and in its original packaging.
Return procedure for LT3942HUFD#PBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
LT3942HUFD#PBF Tags
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