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Analog Devices Inc. LT8391EUFD#TRPBF
- Part No.:
- LT8391EUFD#TRPBF
- Manufacturer:
- Analog Devices Inc.
- Category:
- LED Drivers
- Package:
- 28-WFQFN Exposed Pad
- Datasheet:
-
LT8391EUFD#TRPBF.pdf
- Description:
- IC LED DRIVER CTRLR PWM 28QFN
- Quantity:
- Payment:
- Shipping:
Inventory:4,655
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Product details
Overview
LT8391EUFD#TRPBF 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 (0V–60V), using proprietary peak-buck/peak-boost current mode control. It delivers ±3% LED current accuracy at 100mV full-scale sense voltage, supports 150kHz–650kHz adjustable switching frequency, and integrates bootstrap diodes for simplified gate drive in automotive headlamp and high-power LED lighting systems.
For engineers reviewing the LT8391EUFD#TRPBF datasheet, LT8391EUFD#TRPBF pinout, LT8391EUFD#TRPBF application, or LT8391EUFD#TRPBF equivalent, key selection considerations include its 28-pin 4mm × 5mm QFN package with exposed pad, AEC-Q100 qualification (Grade E, –40°C to +125°C), 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#TRPBF implements a dual-mode current-sense architecture: LSP/LSN monitors inductor current for buck/boost region control, while ISP/ISN senses LED current for regulation and fault detection. Its proprietary peak-buck/peak-boost control ensures continuous conduction and stable loop response across VIN/VOUT ratios from 0.73 (buck-boost→boost) to 1.35 (buck-boost→buck), with precise transition thresholds and no top MOSFET refresh noise.
It integrates two independent gate drivers (TG1/BG1 for buck side; TG2/BG2 for boost side), internal 5V INTVCC LDO, 2V VREF reference, and dedicated PWMTG output for high-side PMOS PWM dimming. Spread spectrum operation (±15% triangle modulation) is enabled by tying SYNC/SPRD to INTVCC, reducing EMI without external components.
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 applications. |
| VOUT Range | 0V to 60V - enables single-inductor LED string drive up to 51V (e.g., 15× white LEDs) without topology change. |
| LED Current Accuracy | ±3% at 100mV full scale - ensures consistent luminance across temperature and unit variation in critical lighting systems. |
| Switching Frequency | 150kHz to 650kHz (adjustable via RT resistor) - balances efficiency, EMI, and inductor size; synchronizable externally. |
| 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. |
| Fault Protection | Open LED (VFB > 0.95V & V(ISP-ISN) < 10mV), short LED (VFB < 0.25V), latch-off/hiccup/keep-running modes - configurable via SS pin resistor. |
| Operating Temp | –40°C to +125°C (Grade E) - qualified per AEC-Q100 for under-hood automotive LED driver use. |
Pinout & Package
LT8391EUFD#TRPBF uses a 28-lead (4mm × 5mm) plastic QFN package with exposed thermal pad (Pin 29 = GND). The package provides θJA = 43°C/W and θJC = 3.4°C/W, requiring soldered thermal pad for reliable power dissipation in 50W+ LED driver designs.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| ISP / ISN | LED current sense differential inputs | Kelvin-connected to RLED; enable ±3% current regulation and open/short LED fault detection. |
| LSP / LSN | Inductor current sense differential inputs | Kelvin-connected to RSENSE; provide real-time inductor current for peak-buck/peak-boost mode control. |
| TG1 / BG1 / BST1 / SW1 | Buck-side N-MOSFET gate drivers & switch node | Drive external high-side/low-side buck switches; integrated bootstrap diode on BST1 simplifies layout. |
| TG2 / BG2 / BST2 / SW2 | Boost-side N-MOSFET gate drivers & switch node | Drive external high-side/low-side boost switches; BST2 supplies gate drive referenced to VOUT. |
| PWMTG | Inverted PWM output for high-side PMOS | Drives external PMOS dimming switch with rail-to-rail swing (VOUT to VOUT–5V); eliminates need for level shifter. |
| CTRL1 / CTRL2 | Analog dimming & thermal derating inputs | Set LED current threshold (0–100mV) and temperature-dependent current roll-off independently. |
| FAULT | Open-drain fault status output | Pulled low during open/short LED faults; updated only during PWM high time for synchronized diagnostics. |
Key Features
| Feature | Design Value |
|---|---|
| Single-inductor 4-switch buck-boost topology | Eliminates need for separate buck/boost ICs or complex multi-inductor designs; reduces BOM count and board area. |
| Proprietary peak-buck/peak-boost current mode | Ensures smooth, low-noise transitions between operating regions without current discontinuity or audible artifacts. |
| Integrated bootstrap Schottky diodes (BST1/BST2) | Removes two external diodes per channel, improving reliability and reducing layout complexity in high-vibration environments. |
| Flicker-free spread spectrum (±15%) | Reduces peak EMI by >10dB without requiring external clock source or compromising regulation stability. |
| Configurable fault response (hiccup/latch-off/keep-running) | Selected via single resistor on SS pin - enables system-level safety compliance (e.g., ASIL-B) without firmware intervention. |
| AEC-Q100 Grade E qualification | Validated for automotive under-hood operation including temperature cycling, humidity, and mechanical shock testing. |
Applications
| Automotive Head Lamps | Industrial High-Bay Lighting |
|---|---|
Use Scenario: Adaptive driving beam (ADB) modules requiring dynamic LED current control across 12V–48V vehicle architectures with cold-crank (4.5V) and load-dump (60V) transients. IC Role / Device Role / Timing Role: Primary LED current controller managing 25V/2A output with seamless buck→buck-boost→boost transitions and ±3% current accuracy. Use Value: Enables single-driver solution for multi-zone ADB, eliminating topology switching delays and ensuring consistent photometric output during voltage dips. |
Use Scenario: 100W+ warehouse lighting with 36–57V LED strings powered from 48V DC microgrids or PoE++ infrastructure. IC Role / Device Role / Timing Role: Constant-current buck-boost regulator supporting wide input (36–60V) and fixed-output (48V) with 98% peak efficiency. Use Value: Delivers stable light output despite grid fluctuations; integrated fault reporting enables predictive maintenance via FAULT pin monitoring. |
| Emergency Vehicle Warning Lights | UV-C Sterilization Systems |
Use Scenario: Flashing red/blue LED arrays in police/fire vehicles requiring 2000:1 PWM dimming for strobe patterns without visible flicker or color shift. IC Role / Device Role / Timing Role: High-speed PWM dimming controller with 40ns PWMTG turn-off delay and rail-to-rail high-side PMOS drive. Use Value: Achieves clean, jitter-free strobes at 1–20Hz with zero current overshoot, meeting SAE J1399 photometric pulse fidelity requirements. |
Use Scenario: Pulsed UV-C LED arrays (275nm) driven at 100–500mA with thermal derating to maintain irradiance stability during extended disinfection cycles. IC Role / Device Role / Timing Role: Precision current regulator with independent CTRL2 thermal feedback for automatic current reduction above 85°C junction. Use Value: Prevents LED wavelength drift and lifetime degradation by maintaining constant photon flux despite heatsink temperature rise. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar LED controller applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LT3956EFE#TRPBF | Fixed boost-only topology; no buck or buck-boost capability; requires separate buck stage for VIN > VOUT. | Suitable only when input is always below output (e.g., 12V → 48V LED string); cannot replace LT8391EUFD#TRPBF in automotive VIN-above-VOUT scenarios. | Select only if system operates exclusively in boost mode and cost sensitivity outweighs topology flexibility. |
| LM3423MH/NOPB | Asynchronous boost controller (external diode); no integrated gate drivers for 4-switch architecture; max 55V VOUT. | Lacks seamless region transition and integrated bootstrap diodes; requires additional MOSFET drivers and higher component count. | Consider for cost-constrained non-automotive applications where 98% efficiency and AEC-Q100 are not required. |
Compared with LT3956EFE#TRPBF and LM3423MH/NOPB, the LT8391EUFD#TRPBF uniquely supports true 4-switch buck-boost operation in a single IC, enabling unified design across 4V–60V input ranges without topology rework - critical for automotive platforms spanning 12V/24V/48V architectures.
Availability
LT8391EUFD#TRPBF is available at Aetrix Electronics and suitable for automotive headlamps, industrial high-bay lighting, emergency warning systems, and UV-C sterilization equipment requiring stable component supply, AEC-Q100 compliance, and long-term production continuity.
Supply support for LT8391EUFD#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, Inc. is a global leader in high-performance analog, mixed-signal, and digital signal processing semiconductors, serving automotive, industrial, communications, and healthcare markets.
The LT8391EUFD#TRPBF belongs to Analog Devices' Power by Linear™ LED controller product line, designed specifically for high-efficiency, high-reliability constant-current LED drivers in demanding environments where input voltage varies widely relative to output.
FAQ
What is the maximum LED string voltage supported by the LT8391EUFD#TRPBF?
The LT8391EUFD#TRPBF supports output voltages up to 60V, with a practical LED string limit of 51V as specified in the datasheet. This accommodates up to 15–17 series white LEDs (3.4V each) or equivalent UV-C/IR configurations, provided external MOSFETs and layout meet voltage derating requirements for reliability.
Does the LT8391EUFD#TRPBF require external bootstrap diodes?
No - the LT8391EUFD#TRPBF integrates Schottky bootstrap diodes on both BST1 and BST2 pins, eliminating the need for external diodes. This reduces component count, improves reliability in automotive vibration environments, and simplifies PCB layout compared to controllers requiring discrete bootstrap solutions.
How is open LED fault detection implemented in the LT8391EUFD#TRPBF?
The LT8391EUFD#TRPBF detects open LED conditions when FB voltage exceeds 0.95V *and* ISP–ISN voltage falls below 10mV. This dual-criteria method prevents false triggers during transient overvoltage events. The FAULT pin pulls low and latches per SS-pin configuration (hiccup/latch-off/keep-running).
Can the LT8391EUFD#TRPBF operate with input voltage equal to output voltage?
Yes - the LT8391EUFD#TRPBF's 4-switch buck-boost architecture enables seamless operation when VIN ≈ VOUT (e.g., 24V input → 24V LED string). Its proprietary peak-buck/peak-boost control maintains continuous inductor current and stable regulation without mode-hopping artifacts or efficiency dropouts.
What thermal grade does the LT8391EUFD#TRPBF carry, and is it AEC-Q100 qualified?
The LT8391EUFD#TRPBF carries the "E" grade, rated for –40°C to +125°C junction temperature and fully AEC-Q100 qualified for automotive applications. It meets stress test requirements including temperature cycling, HTOL, and ESD per AEC-Q100 Rev H, making it suitable for under-hood LED driver use.
LT8391EUFD#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:
- 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#TRPBF FAQ
1.How can I place an order for LT8391EUFD#TRPBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LT8391EUFD#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 LT8391EUFD#TRPBF reliable?
The price and inventory of LT8391EUFD#TRPBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LT8391EUFD#TRPBF is usually 5 days.
3.What payment methods are accepted for LT8391EUFD#TRPBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LT8391EUFD#TRPBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LT8391EUFD#TRPBF?
LT8391EUFD#TRPBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LT8391EUFD#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 LT8391EUFD#TRPBF?
For technical support, including LT8391EUFD#TRPBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LT8391EUFD#TRPBF requirements.
6.How does Aetrix verify that LT8391EUFD#TRPBF is sourced from the original manufacturer or authorized distributors?
All LT8391EUFD#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 LT8391EUFD#TRPBF meets industry standards.
7.What is the process for return or replacement of LT8391EUFD#TRPBF?
All LT8391EUFD#TRPBF units undergo pre-shipment inspection (PSI). If there is an issue with LT8391EUFD#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 LT8391EUFD#TRPBF part is unused and in its original packaging.
Return procedure for LT8391EUFD#TRPBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
LT8391EUFD#TRPBF Tags
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BCR402RE6327HTSA1
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BCR420UE6433HTMA1
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HV9910CLG-G
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