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Analog Devices Inc. LT8391AEUFD#PBF
- Part No.:
- LT8391AEUFD#PBF
- Manufacturer:
- Analog Devices Inc.
- Category:
- LED Drivers
- Package:
- 28-WFQFN Exposed Pad
- Datasheet:
-
LT8391AEUFD#PBF.pdf
- Description:
- IC LED DRIVER CTRLR PWM 28QFN
- Quantity:
- Payment:
- Shipping:
Inventory:172
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Product details
Overview
LT8391AEUFD#PBF from Analog Devices is a synchronous 4-switch buck-boost LED driver controller that regulates constant LED current across input voltages (4V–60V) above, below, or equal to output (0V–60V), using proprietary peak-buck/peak-boost current mode control at 600kHz–2MHz. It delivers ±3% LED current accuracy, supports 2000:1 external PWM dimming, and integrates fault protection for open/short LED conditions-used in automotive headlamps and high-frequency LED lighting systems.
For engineers reviewing the LT8391AEUFD#PBF datasheet, LT8391AEUFD#PBF pinout, LT8391AEUFD#PBF application, or LT8391AEUFD#PBF equivalent, key selection considerations include its 28-pin QFN (4mm × 5mm) package, AEC-Q100 qualification for automotive use, 2MHz switching capability with spread spectrum EMI reduction, and dual analog dimming via CTRL1/CTRL2 with thermal derating support.
Technical Context
The LT8391AEUFD#PBF implements a single-inductor, 4-switch architecture with seamless transitions between buck, buck-boost, and boost regions-governed by VIN/VOUT ratios (e.g., buck-boost to boost at 0.75, boost to buck-boost at 0.85). Its peak-buck/peak-boost current mode control uses one RSENSE on the LSP/LSN pins for both inductor current sensing and reverse-current detection.
It features two independent gate drivers: TG1/BG1 for buck-side N-MOSFETs (with BST1 bootstrap supply) and TG2/BG2 for boost-side N-MOSFETs (with BST2 bootstrap supply), plus PWMTG for external high-side PMOS PWM switching. The VC error amplifier output sets the current comparator threshold, while FB regulates output voltage for fault detection (open LED at VFB > 0.95V & VISP-ISN < 10mV; short LED at VFB < 0.25V).
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 supplies without pre-regulation. |
| VOUT Range | 0V to 60V - enables direct drive of multi-string LED arrays up to 51V forward voltage without external boost stages. |
| Switching Frequency | 600kHz to 2MHz - adjustable via RT resistor; allows compact magnetics and avoids AM radio band; synchronizable or spread-spectrum enabled. |
| LED Current Accuracy | ±3% at 100mV full scale - ensures consistent luminance across temperature and unit-to-unit variation in high-reliability lighting. |
| PWM Dimming Ratio | 2000:1 external, 128:1 internal - enables flicker-free dimming down to 0.05% duty cycle for architectural and automotive adaptive lighting. |
| Package | 28-lead QFN (4mm × 5mm) with exposed pad - provides low thermal resistance (θJC = 3.4°C/W) for high-power LED driver thermal management. |
| Operating Temp | –40°C to +125°C junction - qualified per AEC-Q100 Grade E, suitable for under-hood and exterior automotive lamp environments. |
Pinout & Package
LT8391AEUFD#PBF is housed in a 28-lead plastic QFN (4mm × 5mm) with exposed GND pad soldered to PCB for thermal and electrical integrity. Pin functions are validated per Analog Devices' official datasheet Rev. A.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| BG1, BG2 | Buck/Boost bottom gate drives | Drive N-MOSFET sources to GND; 1.2Ω pull-down resistance enables fast turn-off and prevents shoot-through. |
| TG1, TG2 | Buck/Boost top gate drives | Drive N-MOSFET gates from SWx to BSTx; 2.6Ω pull-up resistance supports 2MHz switching with 25ns rise/fall times. |
| LSP/LSN | Buck-side inductor current sense inputs | Kelvin-connected inputs for accurate peak-current-mode control and reverse-current detection during region transitions. |
| ISP/ISN | LED string current sense inputs | High-side Kelvin sense path enabling ±3% LED current regulation and open/short fault detection. |
| PWMTG | PMOS PWM switch driver | Inverted buffered PWM output swinging from (VOUT –5V) to VOUT - directly drives high-side PMOS for flicker-free dimming. |
| CTRL1/CTRL2 | Analog dimming & thermal derating inputs | Independent 0.25V–2.0V inputs setting LED current threshold linearly (0–90mV) or fixed (100mV); CTRL2 supports NTC-based thermal foldback. |
Key Features
| Feature | Design Value |
|---|---|
| Proprietary peak-buck/peak-boost control | Enables single-inductor operation with smooth, low-noise transitions between buck, buck-boost, and boost modes - eliminates output voltage glitches during VIN/VOUT crossovers. |
| Flicker-free spread spectrum | 25% triangle modulation above oscillator frequency reduces EMI peaks by >10dB, easing CISPR-25 Class 5 compliance in automotive designs. |
| Integrated 5V LDO (INTVCC) | Supplies internal logic and gate drivers from VIN; 145mA current limit and 160mV dropout at 20mA enable self-powered operation without auxiliary supply. |
| Open/short LED fault reporting | FAULT pin asserts open-drain low during detected faults; configurable latch-off, hiccup, or keep-running behavior via SS pin resistor network. |
| AEC-Q100 qualified | Qualified for automotive Grade E (–40°C to +125°C), including HTOL, TC, and ESD testing - meets reliability requirements for front-end lighting modules. |
Applications
| Automotive Head Lamps | Industrial High-Bay Lighting |
|---|---|
Use Scenario: Adaptive driving beam (ADB) systems requiring precise, flicker-free dimming of multiple LED segments across varying battery voltage (6V–16V) and ambient temperature (–40°C to +125°C). IC Role / Device Role / Timing Role: Primary LED current controller managing 4-switch buck-boost topology with seamless region transition and 2000:1 PWM dimming. Use Value: ±3% current accuracy ensures consistent lumen output; AEC-Q100 qualification guarantees field reliability; spread spectrum reduces EMI interference with vehicle CAN/LIN networks. | Use Scenario: High-efficiency 48VDC-powered warehouse lighting with 36–54V LED strings, operating continuously at elevated ambient temperatures (>60°C). IC Role / Device Role / Timing Role: Constant-current LED driver supporting wide VOUT range (0–60V) and high efficiency (>94% at 2MHz) in thermally constrained enclosures. Use Value: 28-lead QFN package with exposed pad enables low θJA (43°C/W); 125°C junction rating sustains performance without derating; internal 5V LDO simplifies BOM. |
| UV-C Disinfection Systems | Avionics Cabin Lighting |
Use Scenario: Pulsed UV-C LED arrays (365nm/275nm) requiring precise current control and rapid on/off cycling for germicidal exposure dosing. IC Role / Device Role / Timing Role: High-speed LED current regulator with sub-100ns PWM-to-PWMTG propagation delay and 2MHz switching for tight pulse-width control. Use Value: 90ns PWM-to-PWMTG turn-on delay ensures accurate timing; ±3% current accuracy maintains consistent UV dose; fault reporting prevents overdrive damage to expensive LEDs. | Use Scenario: FAA-certified aircraft cabin lighting with stringent EMI limits (RTCA DO-160 Section 21), wide input (18–32VDC), and dimming compatibility with DALI-2 interfaces. IC Role / Device Role / Timing Role: EMI-optimized LED driver supporting synchronized 2MHz operation and spread spectrum to meet Class A conducted/radiated emissions. Use Value: SYNC/SPRD pin enables master clock synchronization across multiple drivers; 25% spread spectrum lowers peak radiated emissions by >10dB; FAULT pin integrates with aircraft health monitoring. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar LED driver controller applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LTC3789EUF#PBF | 4-switch buck-boost controller with 4V–36V VIN, no integrated PWM dimming driver; requires external PMOS gate driver; max 1MHz switching. | Lacks PWMTG output and 2000:1 external PWM dimming; not AEC-Q100 qualified; lower frequency limits magnetics size reduction. | Select when cost sensitivity outweighs automotive qualification and high-frequency EMI performance. |
| LM5122MQX/NOPB | Multi-phase synchronous buck controller; no boost/buck-boost capability; 4.5V–60V VIN; supports 2MHz but only buck topology. | Cannot regulate LED current when VIN < VLED; requires separate boost stage for low-input/high-output scenarios. | Select only for pure buck LED applications where VIN consistently exceeds VOUT; unsuitable for automotive start-stop or battery-powered systems. |
Compared with LTC3789EUF#PBF and LM5122MQX/NOPB, the LT8391AEUFD#PBF uniquely combines AEC-Q100 qualification, integrated PWMTG, 2MHz spread-spectrum operation, and true 4-switch buck-boost capability - making it the only option for automotive adaptive front lighting and wide-VIN industrial LED systems requiring flicker-free dimming and robust fault handling.
Availability
LT8391AEUFD#PBF is available at Aetrix Electronics and suitable for automotive headlamp modules, industrial high-bay lighting, UV-C disinfection systems, and avionics cabin lighting requiring stable component supply, long-term lifecycle support, and traceable sourcing.
Supply support for LT8391AEUFD#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 industrial, automotive, communications, and healthcare markets.
The LT8391A product line was designed specifically for high-efficiency, wide-input-range LED driver applications demanding seamless buck-boost operation, automotive-grade reliability, and advanced dimming control - targeting next-generation adaptive lighting and energy-efficient solid-state illumination.
FAQ
What is the maximum switching frequency supported by the LT8391AEUFD#PBF?
The LT8391AEUFD#PBF supports an adjustable switching frequency from 600kHz to 2MHz, set via the RT pin resistor. At RT = 59.0kΩ, the typical frequency is 2MHz. This high-frequency capability enables smaller inductors and capacitors, reducing solution size and improving transient response in LED driver designs.
Does the LT8391AEUFD#PBF integrate a high-side PMOS driver?
Yes, the LT8391AEUFD#PBF integrates the PWMTG pin-a buffered, inverted PWM output that drives external high-side PMOS switches with rail-to-rail swing from (VOUT –5V) to VOUT. This eliminates the need for discrete level-shifters and ensures flicker-free dimming with sub-100ns propagation delay, critical for automotive ADB systems.
How does the LT8391AEUFD#PBF handle LED open-circuit faults?
The LT8391AEUFD#PBF detects open LED conditions when VFB > 0.95V and VISP-ISN < 10mV, pulling the open-drain FAULT pin low. Fault response mode (hiccup, latch-off, or keep-running) is configured via a resistor from SS to VREF. This real-time reporting enables system-level diagnostics and safe shutdown in automotive lighting modules.
Is the LT8391AEUFD#PBF qualified for automotive applications?
Yes, the LT8391AEUFD#PBF is AEC-Q100 qualified for Grade E (–40°C to +125°C junction temperature) and manufactured under controlled automotive processes. It includes built-in protections (open/short LED, overtemperature), spread-spectrum EMI reduction, and robust gate drivers meeting ISO 16750-2 load-dump and cold-crank requirements.
What package type and thermal characteristics does the LT8391AEUFD#PBF use?
The LT8391AEUFD#PBF uses a 28-lead QFN package (4mm × 5mm) with exposed GND pad. Its thermal resistance is θJA = 43°C/W and θJC = 3.4°C/W, enabling efficient heat dissipation in high-power LED driver applications. The exposed pad must be soldered to a PCB ground plane for optimal thermal and electrical performance.
LT8391AEUFD#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:
- 600kHz ~ 2MHz
- 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)
LT8391AEUFD#PBF FAQ
1.How can I place an order for LT8391AEUFD#PBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LT8391AEUFD#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 LT8391AEUFD#PBF reliable?
The price and inventory of LT8391AEUFD#PBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LT8391AEUFD#PBF is usually 5 days.
3.What payment methods are accepted for LT8391AEUFD#PBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LT8391AEUFD#PBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LT8391AEUFD#PBF?
LT8391AEUFD#PBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LT8391AEUFD#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 LT8391AEUFD#PBF?
For technical support, including LT8391AEUFD#PBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LT8391AEUFD#PBF requirements.
6.How does Aetrix verify that LT8391AEUFD#PBF is sourced from the original manufacturer or authorized distributors?
All LT8391AEUFD#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 LT8391AEUFD#PBF meets industry standards.
7.What is the process for return or replacement of LT8391AEUFD#PBF?
All LT8391AEUFD#PBF units undergo pre-shipment inspection (PSI). If there is an issue with LT8391AEUFD#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 LT8391AEUFD#PBF part is unused and in its original packaging.
Return procedure for LT8391AEUFD#PBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
LT8391AEUFD#PBF Tags
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