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Analog Devices Inc. LT8391EUFD#PBF
- Part No.:
- LT8391EUFD#PBF
- Manufacturer:
- Analog Devices Inc.
- Category:
- LED Drivers
- Package:
- 28-WFQFN Exposed Pad
- Datasheet:
-
LT8391EUFD#PBF.pdf
- Description:
- IC LED DRIVER CTRLR PWM 28QFN
- Quantity:
- Payment:
- Shipping:
Inventory:2,975
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Product details
Overview
LT8391EUFD#PBF from Analog Devices is a synchronous 4-switch buck-boost LED controller that regulates constant LED current across input voltages (4V–60V) both above, below, or equal to output voltage (0V–60V), using proprietary peak-buck/peak-boost current mode control. It delivers ±3% LED current accuracy at 100mV full scale, supports 150kHz–650kHz adjustable switching frequency, and integrates bootstrap diodes for automotive headlamp and high-power industrial LED driver applications.
For engineers reviewing the LT8391EUFD#PBF datasheet, LT8391EUFD#PBF pinout, LT8391EUFD#PBF application, or LT8391EUFD#PBF equivalent, key selection considerations include its 28-pin QFN (4mm × 5mm) package with exposed pad, AEC-Q100 qualification, 2000:1 external PWM dimming capability, open/short LED fault reporting via FAULT pin, and seamless region transitions without audible noise or current discontinuity.
Technical Context
The LT8391EUFD#PBF implements a dual-mode current-sense architecture: LSP/LSN senses inductor current for buck/boost/buck-boost region control, while ISP/ISN directly measures LED current for regulation and fault detection. Its peak-buck/peak-boost control logic dynamically selects gate drive timing-TG1/BG1 active in buck, TG2/BG2 in boost, and complementary pairs in buck-boost-to maintain continuous conduction and low EMI.
Switching is governed by an internal oscillator set via RT (150–650 kHz), with optional synchronization (SYNC/SPRD pin) or ±15% triangle spread spectrum for EMI reduction. Fault protection includes FB-based open/short LED detection (0.95V/0.25V thresholds) and ISP/ISN-based overcurrent (750mV) and open-LED (10mV) sensing, with programmable response (hiccup/latch-off/keep-running) via SS pin resistor.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| VIN Range | 4V to 60V - supports wide-input automotive battery (cold-crank to load-dump) and industrial DC bus systems. |
| VOUT Range | 0V to 60V - enables single-inductor operation across LED string voltages from 1V to 51V without topology change. |
| LED Current Accuracy | ±3% at 100mV full scale - ensures precise luminance control in safety-critical lighting. |
| Dimming Ratio | 2000:1 external PWM, 128:1 internal PWM - meets flicker-free requirements for camera flash and adaptive driving beam (ADB). |
| Switching Frequency | 150kHz to 650kHz (adjustable via RT) - allows optimization of magnetics size vs. EMI compliance (CISPR 25 Class 5). |
| Operating Temp | –40°C to +125°C junction - qualified for under-hood automotive environments per AEC-Q100 Grade E. |
| Fault Reporting | Open/short LED detection with FAULT pin open-drain output - enables system-level diagnostics and fail-safe shutdown. |
Pinout & Package
LT8391EUFD#PBF uses a 28-lead (4mm × 5mm) plastic QFN package 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 integrity.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| ISP / ISN | High-side LED current sense inputs | Kelvin-connected differential pair for ±3% LED current regulation; rejects common-mode noise up to 60V. |
| LSP / LSN | Buck-side inductor current sense inputs | Provides real-time inductor current for peak-buck/peak-boost mode transition and reverse-current protection. |
| TG1 / BG1 / SW1 / BST1 | Buck-side power switch interface | Drives N-channel MOSFETs in buck configuration; integrated bootstrap diode reduces BOM count. |
| TG2 / BG2 / SW2 / BST2 | Boost-side power switch interface | Drives N-channel MOSFETs in boost configuration; independent bootstrap supply prevents shoot-through. |
| PWMTG | High-side PMOS PWM switch driver | Inverted buffered PWM output referenced to VOUT; drives external PMOS for analog+PWM hybrid dimming. |
| CTRL1 / CTRL2 | Analog dimming and thermal derating inputs | Enable 20:1 analog dimming (±3% accuracy) and temperature-compensated current derating via resistor dividers. |
| FAULT | Open-drain fault status output | Pulled low on open LED (VFB > 0.95V & V(ISP-ISN) < 10mV) or short LED (VFB < 0.25V); requires external pull-up. |
Key Features
| Feature | Design Value |
|---|---|
| 4-switch single-inductor architecture | Eliminates need for separate buck/boost ICs or complex multiphase controllers in wide-VIN LED systems. |
| Proprietary peak-buck/peak-boost control | Ensures smooth, low-noise transitions between operating regions without current discontinuity or audible artifacts. |
| Integrated bootstrap diodes | Reduces external component count by two Schottky diodes per channel, improving reliability and layout simplicity. |
| Flicker-free spread spectrum | ±15% triangle modulation around switching frequency lowers peak EMI by >10dB without affecting regulation stability. |
| AEC-Q100 qualified | Validated for automotive applications including headlamps, DRLs, and interior ambient lighting per Grade E stress testing. |
Applications
| Automotive Head Lamps | Industrial High-Bay Lighting |
|---|---|
Use Scenario: Adaptive front-lighting system (AFS) with matrix LED arrays requiring precise current control across 9–16V battery range and 30–55V LED strings. IC Role / Device Role / Timing Role: Primary LED current controller managing four-quadrant buck-boost conversion and synchronized PWM dimming for pixel-level beam shaping. Use Value: Enables seamless transition between low-beam (buck), adaptive cornering (buck-boost), and high-beam (boost) modes with <1µs fault response time. | Use Scenario: 100W+ warehouse lighting powered from 24–48V DC microgrids with varying line impedance and thermal derating needs. IC Role / Device Role / Timing Role: Constant-current LED driver with thermal foldback (via CTRL2) and programmable fault recovery to sustain uptime in unattended facilities. Use Value: Delivers 98% efficiency at 2A/25V output while maintaining ±3% current accuracy across –40°C to +85°C ambient. |
| UV-C Sterilization Modules | Emergency Vehicle Warning Lights |
Use Scenario: Pulsed UV-C LED arrays (265nm, 350mA–1A) requiring precise current pulses and thermal monitoring during duty-cycled operation. IC Role / Device Role / Timing Role: High-accuracy current source with fast PWM dimming (2000:1 ratio) and integrated overtemperature protection via CTRL2. Use Value: Supports 100ns PWM edge control and maintains ±3% current regulation even during rapid thermal transients. | Use Scenario: Flashing red/blue warning lights on emergency vehicles powered from 12V/24V batteries with load-dump immunity up to 60V. IC Role / Device Role / Timing Role: Robust LED driver with 4–60V input tolerance, open/short LED fault reporting, and latch-off protection during wiring faults. Use Value: Guarantees fail-safe operation with FAULT pin signaling and automatic shutdown on LED string failure. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar LED controller applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LT3965EFE#PBF | 4-switch buck-boost LED controller in 28-lead TSSOP; same 4–60V VIN, but fixed 200kHz–2MHz sync range and no spread spectrum. | Targeted at space-constrained industrial lighting; lacks AEC-Q100 qualification and integrated bootstrap diodes. | Select when board area permits TSSOP and spread spectrum is not required for EMI compliance. |
| LM3492QMH/NOPB | 2-switch buck-boost controller (no 4-switch architecture); 4.5–60V VIN, 0–40V VOUT, but cannot regulate LED current below VOUT or above VIN without external sense amplification. | Suitable for cost-sensitive non-automotive LED drivers where region transitions are infrequent and ±5% current accuracy is acceptable. | Choose only if input/output overlap is limited and thermal derating or AEC-Q100 is not required. |
Compared with LT3965EFE#PBF and LM3492QMH/NOPB, the LT8391EUFD#PBF uniquely combines AEC-Q100 qualification, integrated bootstrap diodes, ±15% spread spectrum, and seamless 4-switch region transitions-making it the only option for automotive-grade adaptive lighting with flicker-free dimming and robust fault handling.
Availability
LT8391EUFD#PBF is available at Aetrix Electronics and suitable for automotive headlamp design, industrial high-bay LED drivers, and UV-C sterilization modules requiring stable component supply, long-term lifecycle support, and AEC-Q100-compliant sourcing.
Supply support for LT8391EUFD#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 leader in high-performance analog, mixed-signal, and digital signal processing semiconductors, serving precision instrumentation, industrial automation, and automotive safety markets.
The LT8391 product line was designed specifically for high-reliability, wide-input-range LED driver applications demanding seamless buck/boost/buck-boost operation, automotive qualification, and advanced dimming capabilities-targeting next-generation adaptive lighting and industrial solid-state illumination.
FAQ
What is the maximum LED string voltage supported by the LT8391EUFD#PBF?
The LT8391EUFD#PBF supports output voltages up to 60V, with a specified 51V LED string rating per Analog Devices' typical application data. This enables direct drive of multi-series white or UV-C LED strings without intermediate voltage conversion, maintaining ±3% current regulation accuracy across the full 0–60V VOUT range.
Does the LT8391EUFD#PBF require external bootstrap diodes?
No, the LT8391EUFD#PBF integrates bootstrap Schottky diodes on both BST1 and BST2 pins, eliminating the need for two external diodes typically required in 4-switch buck-boost controllers. This reduces bill-of-materials count, improves reliability, and simplifies PCB layout-confirmed in the Pin Functions section of the official datasheet.
How does the LT8391EUFD#PBF handle transitions between buck, buck-boost, and boost operating regions?
The LT8391EUFD#PBF uses a proprietary peak-buck/peak-boost current mode control scheme that monitors VIN/VOUT ratios and adjusts gate drive timing in real time. Transitions occur smoothly at defined thresholds (e.g., buck-to-buck-boost at VIN/VOUT = 1.16–1.20) without current discontinuity, audible noise, or regulation error-verified in Typical Performance Characteristics Figure G24.
Can the LT8391EUFD#PBF be used in AEC-Q100 automotive applications?
Yes, the LT8391EUFD#PBF is explicitly qualified to AEC-Q100 Grade E (–40°C to +125°C junction), as stated in the ORDER INFORMATION table and FEATURES list. It is designated for automotive headlamps, running lamps, and interior lighting where reliability under temperature cycling, vibration, and voltage transients is mandatory.
What fault conditions trigger the FAULT pin on the LT8391EUFD#PBF?
The FAULT pin on the LT8391EUFD#PBF is pulled low during open LED (VFB > 0.95V and V(ISP-ISN) < 10mV) or short LED (VFB < 0.25V) conditions. Fault status is updated only during PWM high state and latched during PWM low state, enabling deterministic system-level fault logging without spurious triggering.
LT8391EUFD#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 Controller
- Topology:
- Step-Down (Buck), Step-Up (Boost)
- Internal Switch(s):
- No
- Number of Outputs:
- 1
- Voltage - Supply (Min):
- 4V
- Voltage - Supply (Max):
- 60V
- Voltage - Output:
- 60V
- Current - Output / Channel:
- -
- Frequency:
- 150kHz ~ 650kHz
- Dimming:
- Analog, PWM
- Applications:
- Lighting
- Operating Temperature:
- -40°C ~ 125°C (TJ)
- Grade:
- Automotive
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 28-QFN (4x5)
LT8391EUFD#PBF FAQ
1.How can I place an order for LT8391EUFD#PBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LT8391EUFD#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 LT8391EUFD#PBF reliable?
The price and inventory of LT8391EUFD#PBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LT8391EUFD#PBF is usually 5 days.
3.What payment methods are accepted for LT8391EUFD#PBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LT8391EUFD#PBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LT8391EUFD#PBF?
LT8391EUFD#PBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LT8391EUFD#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 LT8391EUFD#PBF?
For technical support, including LT8391EUFD#PBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LT8391EUFD#PBF requirements.
6.How does Aetrix verify that LT8391EUFD#PBF is sourced from the original manufacturer or authorized distributors?
All LT8391EUFD#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 LT8391EUFD#PBF meets industry standards.
7.What is the process for return or replacement of LT8391EUFD#PBF?
All LT8391EUFD#PBF units undergo pre-shipment inspection (PSI). If there is an issue with LT8391EUFD#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 LT8391EUFD#PBF part is unused and in its original packaging.
Return procedure for LT8391EUFD#PBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
LT8391EUFD#PBF Tags
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