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Analog Devices Inc. LT8391AHUFD#TRPBF
- Part No.:
- LT8391AHUFD#TRPBF
- Manufacturer:
- Analog Devices Inc.
- Category:
- LED Drivers
- Package:
- 28-WFQFN Exposed Pad
- Datasheet:
-
LT8391AHUFD#TRPBF.pdf
- Description:
- IC LED DRIVER CTRLR PWM 28QFN
- Quantity:
- Payment:
- Shipping:
Inventory:2,777
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Product details
Overview
LT8391AHUFD#TRPBF from Analog Devices is a synchronous 4-switch buck-boost LED controller IC designed for high-frequency, wide-input/output LED driver applications. It operates from 4V to 60V input and delivers 0V to 60V output with ±3% LED current accuracy, 2MHz switching capability, and seamless region transitions-enabling use in automotive headlamps, industrial lighting, and battery-powered LED systems.
For engineers reviewing the LT8391AHUFD#TRPBF datasheet, LT8391AHUFD#TRPBF pinout, LT8391AHUFD#TRPBF application, or LT8391AHUFD#TRPBF equivalent, key selection criteria include its AEC-Q100 qualification (H-grade, –40°C to 150°C), 28-pin QFN (4mm × 5mm) package with exposed pad, 2000:1 external PWM dimming, peak-buck/peak-boost current mode control, and integrated fault reporting via open/short LED detection.
Technical Context
The LT8391AHUFD#TRPBF implements a proprietary peak-buck/peak-boost current mode architecture that uses a single inductor and dual current sense paths (LSP/LSN for buck-side, ISP/ISN for LED-side) to maintain regulation across VIN < VOUT, VIN ≈ VOUT, and VIN > VOUT conditions. Its internal oscillator supports fixed-frequency operation from 600kHz to 2MHz via RT resistor or external SYNC, with optional 25% triangle spread spectrum for EMI reduction.
Control logic integrates dual analog dimming inputs (CTRL1/CTRL2) for precise LED current scaling and thermal derating, plus dedicated PWM dimming (PWM/PWMTG) driving an external high-side PMOS switch. Fault handling includes latch-off, hiccup, or keep-running modes configurable via SS pin resistor, with FAULT pin reporting open/short LED events synchronized to PWM high time.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 4V to 60V - supports 12V/24V/48V automotive and industrial rails, including cold-crank and load-dump transients. |
| Output Voltage Range | 0V to 60V - enables direct drive of multi-string LED arrays up to 51V forward voltage without intermediate conversion. |
| Switching Frequency | 600kHz to 2MHz - adjustable via RT pin; higher frequencies allow smaller magnetics and reduced EMI filter size. |
| LED Current Accuracy | ±3% at 100mV full scale - ensures consistent luminance across temperature and unit-to-unit variation in production. |
| PWM Dimming Ratio | 2000:1 external, 128:1 internal - enables flicker-free dimming down to 0.05% duty cycle for high-end lighting control. |
| Operating Temperature | –40°C to +150°C junction - qualified per AEC-Q100 Grade H for under-hood automotive LED drivers. |
| Package | 28-lead QFN (4mm × 5mm) with exposed thermal pad - provides low θJC = 3.4°C/W for high-power thermal management. |
Pinout & Package
LT8391AHUFD#TRPBF is housed in a 28-lead plastic QFN package (4mm × 5mm) with exposed GND pad (Pin 29) requiring PCB soldering for thermal and electrical integrity. θJA = 43°C/W, θJC = 3.4°C/W.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| BG1, BG2 | Buck/Boost bottom gate drivers | Drive N-channel MOSFETs from GND to INTVCC; enable synchronous rectification in both buck and boost phases. |
| TG1, TG2 | Buck/Boost top gate drivers | Drive N-channel MOSFETs with bootstrapped swing (SWx to BSTx); support high-side switching without external high-voltage drivers. |
| LSP/LSN | Buck-side inductor current sense | Kelvin-connected inputs for accurate peak-current-mode control during buck operation and reverse-current detection. |
| ISP/ISN | LED string current sense | Kelvin-connected inputs referenced to VOUT; provide precise LED current regulation independent of VOUT level. |
| PWMTG | PWM top-gate driver output | Inverted buffered PWM signal swinging from (VOUT –5V) to VOUT; directly drives external high-side PMOS dimming switch. |
| FAULT | Open-drain fault indicator | Pulled low during open LED (VFB > 0.95V & V(ISP-ISN) < 10mV) or short LED (VFB < 0.25V); status updated only during PWM high time. |
Key Features
| Feature | Design Value |
|---|---|
| 4-switch single-inductor topology | Eliminates need for separate buck and boost converters; reduces BOM count, board area, and EMI by sharing one magnetic component. |
| Flicker-free spread spectrum | 25% triangle modulation on internal oscillator when SYNC/SPRD tied to INTVCC - lowers peak EMI by spreading energy across frequency band. |
| Seamless region transition | No discontinuity or audible noise during VIN/VOUT crossover; buck-boost to boost transition occurs at VIN/VOUT = 0.75 ±0.02. |
| Thermal derating via CTRL2 | Programmable LED current reduction using NTC-based divider on CTRL2 - protects LEDs and driver under sustained high-temperature operation. |
| Configurable fault response | SS pin resistor selects hiccup (no resistor), latch-off (499kΩ), or keep-running (100kΩ) behavior during LED faults - enables system-level safety design. |
Applications
| Automotive Head Lamps | High-Frequency Industrial Lighting |
|---|---|
Use Scenario: Adaptive front-lighting systems (AFS) requiring dynamic beam shaping and instant dimming across varying battery voltage (6V–16V) and LED string configurations (12V–48V). IC Role / Device Role / Timing Role: Primary LED current controller managing 4-switch buck-boost power stage, PWM dimming, and open/short LED fault reporting in real time. Use Value: Enables AEC-Q100-compliant, 2MHz operation for compact magnetics and low EMI - critical for integration near sensitive ADAS sensors. | Use Scenario: Factory floor LED task lighting powered from 24V DC bus, requiring stable brightness over wide ambient temperature (–20°C to +70°C) and input ripple. IC Role / Device Role / Timing Role: Constant-current regulator with thermal derating (via CTRL2) and ±3% current accuracy across line/load/temperature. Use Value: Maintains consistent lumen output despite voltage sag or thermal drift - reducing maintenance and calibration cycles in production environments. |
| Battery-Powered Emergency Lighting | UV-C LED Disinfection Systems |
Use Scenario: Portable emergency exit signs powered by 12V sealed lead-acid or Li-ion packs, operating from 10V to 14.4V while driving 36V LED strings. IC Role / Device Role / Timing Role: Wide-VIN buck-boost controller enabling single-stage regulation without pre-regulator or boost-only limitations. Use Value: Extends runtime by maintaining >94% efficiency at 2MHz across entire battery discharge curve - minimizing heat generation in enclosed enclosures. | Use Scenario: Pulsed UV-C LED arrays (365nm/275nm) requiring precise current control, fast PWM dimming, and overtemperature protection during sterilization cycles. IC Role / Device Role / Timing Role: High-accuracy current source with 2000:1 PWM dimming and programmable thermal foldback (CTRL2) to prevent LED degradation. Use Value: Ensures repeatable UV dose delivery by eliminating current drift during thermal soak - critical for medical-grade disinfection validation. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar LED controller applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LT8391AEUFD#TRPBF | Same silicon, –40°C to +125°C operating range; lower max junction temperature rating. | Suitable for non-automotive industrial or commercial lighting where ambient temperature remains below 125°C. | Select when AEC-Q100 qualification and 150°C operation are not required - offers cost and supply chain flexibility. |
| LT8390AHUFD#TRPBF | Predecessor with 1MHz max switching frequency, no spread spectrum, and 1000:1 external PWM dimming. | Lacks 2MHz capability and EMI-reduction features; limited for space-constrained or high-EMI-sensitive designs. | Choose only if legacy design reuse or lower-frequency magnetics are mandated - not recommended for new designs targeting EMI compliance. |
Compared with LT8391AEUFD#TRPBF and LT8390AHUFD#TRPBF, the LT8391AHUFD#TRPBF delivers higher thermal robustness (150°C), superior EMI performance (spread spectrum), and extended dimming resolution - making it optimal for next-generation automotive and high-reliability industrial LED systems.
Availability
LT8391AHUFD#TRPBF is available at Aetrix Electronics and suitable for automotive headlamps, industrial lighting systems, and battery-powered emergency signage requiring stable component supply, AEC-Q100 qualification, and long-term lifecycle support.
Supply support for LT8391AHUFD#TRPBF 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 (now part of Analog Devices, Inc., a wholly owned subsidiary of Analog Devices, Inc.) is a global leader in high-performance analog, mixed-signal, and digital signal processing semiconductors.
The LT8391A product line was engineered specifically for high-efficiency, wide-input-range LED driver applications demanding seamless buck-boost operation, precision current regulation, and automotive-grade reliability - targeting headlamp, signaling, and specialty lighting markets.
FAQ
What is the maximum switching frequency supported by the LT8391AHUFD#TRPBF?
The LT8391AHUFD#TRPBF supports a maximum switching frequency of 2MHz, set via the RT pin resistor or external SYNC signal. At 2MHz, it achieves 94% efficiency in a 24W (16V, 1.5A) buck-boost LED driver configuration, enabling compact magnetics and reduced EMI filter requirements. Operation above 2MHz is not specified or guaranteed.
Does the LT8391AHUFD#TRPBF require external MOSFETs for the 4-switch buck-boost topology?
Yes, the LT8391AHUFD#TRPBF is a controller IC and requires four external N-channel MOSFETs (two for buck side, two for boost side) plus external gate drive components (bootstrap capacitors, diodes). It does not integrate power switches. The BG1/BG2 and TG1/TG2 pins provide gate drive signals optimized for standard logic-level and high-side N-MOSFETs.
How is thermal derating implemented on the LT8391AHUFD#TRPBF?
Thermal derating on the LT8391AHUFD#TRPBF is implemented via the CTRL2 pin, which accepts an analog voltage (0.25V–1.35V) to linearly scale the LED current sense threshold. When paired with an NTC thermistor divider from VREF to GND, CTRL2 enables automatic LED current reduction as temperature rises - protecting LEDs and driver under sustained high-temperature operation without external microcontroller intervention.
What fault protection mechanisms does the LT8391AHUFD#TRPBF provide for LED strings?
The LT8391AHUFD#TRPBF provides open LED detection (VFB > 0.95V & V(ISP-ISN) < 10mV), short LED detection (VFB < 0.25V), and overvoltage protection (VFB > 1.05V). Fault status is reported on the open-drain FAULT pin and can trigger hiccup, latch-off, or keep-running behavior based on the SS pin configuration - enabling flexible system-level safety responses without additional monitoring circuitry.
Is the LT8391AHUFD#TRPBF pin-compatible with other variants in the LT8391A family?
Yes, the LT8391AHUFD#TRPBF shares identical pinout and footprint with all other LT8391A variants in the 28-lead QFN (UFD) package, including LT8391AEUFD#TRPBF and LT8391AIUFD#TRPBF. Differences are limited to operating temperature grade and associated qualification - allowing drop-in replacement within the same package variant when thermal or automotive requirements change.
LT8391AHUFD#TRPBF Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- -
- Package/Case:
- 28-WFQFN Exposed Pad
- Packaging:
- Tape & Reel (TR)
- 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 ~ 150°C (TJ)
- Grade:
- Automotive
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 28-QFN (4x5)
LT8391AHUFD#TRPBF FAQ
1.How can I place an order for LT8391AHUFD#TRPBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LT8391AHUFD#TRPBF 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 LT8391AHUFD#TRPBF reliable?
The price and inventory of LT8391AHUFD#TRPBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LT8391AHUFD#TRPBF is usually 5 days.
3.What payment methods are accepted for LT8391AHUFD#TRPBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LT8391AHUFD#TRPBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LT8391AHUFD#TRPBF?
LT8391AHUFD#TRPBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LT8391AHUFD#TRPBF 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 LT8391AHUFD#TRPBF?
For technical support, including LT8391AHUFD#TRPBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LT8391AHUFD#TRPBF requirements.
6.How does Aetrix verify that LT8391AHUFD#TRPBF is sourced from the original manufacturer or authorized distributors?
All LT8391AHUFD#TRPBF 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 LT8391AHUFD#TRPBF meets industry standards.
7.What is the process for return or replacement of LT8391AHUFD#TRPBF?
All LT8391AHUFD#TRPBF units undergo pre-shipment inspection (PSI). If there is an issue with LT8391AHUFD#TRPBF, 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 LT8391AHUFD#TRPBF part is unused and in its original packaging.
Return procedure for LT8391AHUFD#TRPBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
LT8391AHUFD#TRPBF Tags
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BCR402RE6327HTSA1
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BCR430UXTSA2
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BCR420UE6433HTMA1
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BCR420UE6327HTSA1
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BCR421UE6327HTSA1
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LYT1604D-TL
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HV9910CLG-G
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CL2N8-G
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BCR420UW6-7
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BCR421UW6-7
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BCR420UFD-7
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BCR421UFD-7
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