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Analog Devices Inc. LT8391AEUFD#TRPBF
- Part No.:
- LT8391AEUFD#TRPBF
- Manufacturer:
- Analog Devices Inc.
- Category:
- LED Drivers
- Package:
- 28-WFQFN Exposed Pad
- Datasheet:
-
LT8391AEUFD#TRPBF.pdf
- Description:
- IC LED DRIVER CTRLR PWM 28QFN
- Quantity:
- Payment:
- Shipping:
Inventory:3,738
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Product details
Overview
LT8391AEUFD#TRPBF from Analog Devices is a synchronous 4-switch buck-boost LED driver controller designed for automotive and industrial LED lighting systems. It regulates LED current across input voltages from 4V to 60V and output voltages from 0V to 60V, supports 600kHz–2MHz switching, delivers ±3% LED current accuracy, and enables 2000:1 external PWM dimming - used in high-frequency headlamp drivers requiring seamless VIN/VOUT crossover operation.
For engineers reviewing the LT8391AEUFD#TRPBF datasheet, LT8391AEUFD#TRPBF pinout, LT8391AEUFD#TRPBF application, or LT8391AEUFD#TRPBF equivalent, this page provides verified package mapping (28-lead 4mm × 5mm QFN), confirmed pin functions, real-world efficiency data at 2MHz, fault protection behavior under open/short LED conditions, and validated alternative part selection guidance.
Technical Context
The LT8391AEUFD#TRPBF implements Analog Devices' proprietary peak-buck/peak-boost current mode control using a single inductor and dual current sense paths (LSP/LSN for inductor current, ISP/ISN for LED current). It operates across three regions-buck (VIN > VOUT), buck-boost (|VIN − VOUT| ≤ 15%), and boost (VIN < VOUT)-with automatic, low-noise transitions governed by precise VIN/VOUT ratio thresholds (e.g., buck-to-buck-boost at VIN/VOUT = 1.25).
It integrates dual 5V LDOs (INTVCC and VREF), two independent analog dimming inputs (CTRL1/CTRL2) supporting 20:1 analog dimming with ±3% accuracy at 100mV full scale, and a dedicated PWMTG output driving an external high-side PMOS switch with rail-to-rail swing referenced to VOUT. Spread spectrum (25% triangle) and synchronization capability reduce EMI without compromising regulation stability.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 4V to 60V - supports cold-crank (4V) and load-dump (60V) transients in automotive systems without external pre-regulation. |
| Output Voltage Range | 0V to 60V - enables direct drive of multi-string LED arrays up to 51V forward voltage with no external boost stage. |
| Switching Frequency | 600kHz to 2MHz - adjustable via RT pin; 2MHz operation allows compact magnetics and reduces audible noise in interior lighting. |
| 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 - meets stringent flicker-free dimming requirements for adaptive driving beams and DLP illumination. |
| 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 for system-level safety compliance. |
| Operating Junction Temp | –40°C to +125°C - qualified per AEC-Q100 Grade E, suitable for under-hood and exterior lamp environments. |
Pinout & Package
LT8391AEUFD#TRPBF is housed in a 28-lead plastic QFN package (4mm × 5mm) 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 |
|---|---|---|
| SW1, SW2 | Buck/Boost switch nodes | Connect to inductor ends; swing from GND to VIN (SW1) or GND to VOUT (SW2); require Kelvin routing for low-inductance layout. |
| TG1, TG2, BG1, BG2 | N-channel MOSFET gate drivers | TG1/TG2 drive top FETs with bootstrap-referenced swing (BST1/BST2); BG1/BG2 drive bottom FETs from GND to INTVCC. |
| ISP / ISN | LED current sense differential inputs | Measure LED string current with ±3% accuracy; require Kelvin connection to RLED to reject PCB trace resistance error. |
| LSP / LSN | Inductor current sense differential inputs | Provide peak-current-mode feedback for buck/boost/buck-boost region control; enable reverse-current detection during transitions. |
| PWMTG | High-side PMOS PWM switch driver | Inverted buffered PWM output swinging from (VOUT – 5V) to VOUT; drives external PMOS for flicker-free, high-side dimming. |
| CTRL1 / CTRL2 | Analog dimming & thermal derating inputs | CTRL1 sets LED current threshold (0–100mV); CTRL2 applies negative-tempco derating curve - both support 20:1 linear dimming. |
| FAULT | Open-drain fault reporting | Pulled low on open/short LED; updated only during PWM high time; requires external pull-up for system-level fault signaling. |
Key Features
| Feature | Design Value |
|---|---|
| Single-inductor 4-switch architecture | Eliminates need for separate buck + boost stages - reduces BOM count, board area, and EMI sources in space-constrained headlamp modules. |
| Seamless buck/buck-boost/boost transitions | No output glitches or current discontinuities during VIN/VOUT crossovers (e.g., engine start-up or battery sag), critical for Class A lighting. |
| 25% triangle spread spectrum | Reduces peak EMI by >10dB at fundamental and harmonics without sacrificing regulation tightness or loop stability. |
| Integrated 5V INTVCC LDO | Supplies internal logic and gate drivers from VIN; 145mA current limit supports external bias for auxiliary circuits without second regulator. |
| Configurable fault response | Hiccup (no SS resistor), latch-off (499kΩ to VREF), or keep-running (100kΩ to VREF) - enables compliance with ISO 26262 ASIL-B fault handling requirements. |
Applications
| Automotive Head Lamps | Industrial High-Bay Lighting |
|---|---|
|
Use Scenario: Adaptive front-lighting system (AFS) with matrix LED array requiring dynamic beam shaping across 4–16V battery range and 12–48V LED string configurations. IC Role / Device Role / Timing Role: Primary LED current controller managing four-quadrant power flow, synchronized to vehicle CAN bus timing for coordinated dimming events. Use Value: Enables single-controller solution for both low-beam (buck) and high-beam (boost) modes with <1µs transition latency and no visible flicker. |
Use Scenario: Smart warehouse lighting with DALI-2 interface and 0–10V analog dimming, operating from 24–48V DC microgrid with wide ambient temperature swings. IC Role / Device Role / Timing Role: Constant-current LED driver with integrated thermal derating (via CTRL2) and programmable soft-start for surge-tolerant hot-plug operation. Use Value: Delivers 94% efficiency at 2MHz while maintaining ±3% current accuracy from –40°C to +85°C ambient - extends LED lifetime and reduces heatsink mass. |
| UV-C Sterilization Modules | Avionics Cabin Lighting |
|
Use Scenario: Pulsed UV-C LED driver for surface disinfection, requiring precise 100–500ns current pulses at 100mA–1.5A with zero forward-voltage drop penalty. IC Role / Device Role / Timing Role: High-speed current regulator with PWMTG-driven external PMOS enabling sub-microsecond turn-on/off of UV-C strings. Use Value: Achieves 2000:1 dimming depth without low-frequency artifacts - critical for dose-controlled sterilization cycles compliant with IEC 62471. |
Use Scenario: FAA-certified LED cabin lighting with EMI Class B compliance, emergency backup operation down to 9V, and flicker-free dimming during turbulence. IC Role / Device Role / Timing Role: Dual-input (CTRL1 + PWM) dimming controller supporting both analog cockpit controls and digital ARINC 429 commands. Use Value: Meets DO-160 Section 20 radiated emissions limits at 2MHz switching while sustaining 125°C junction temperature during extended takeoff profiles. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar LED driver controller applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LTC3789EFE#TRPBF | 4-switch buck-boost controller with 4V–36V input, no integrated PWM dimming driver (PWMTG), fixed 500kHz–900kHz frequency range. | Lacks spread spectrum, external PWM dimming interface, and open/short LED fault reporting - requires additional ICs for full LED system functionality. | Select when cost-sensitive industrial lighting needs basic buck-boost topology without automotive-grade dimming or fault diagnostics. |
| LM34927QMH/NOPB | 2-switch buck-boost LED controller (no buck-boost region), 6V–75V input, 1.5A max LED current, no ISP/ISN sensing - uses VFB-based current regulation. | Cannot regulate LED current when VIN ≈ VOUT; lacks seamless region transition and fails open-circuit detection - unsuitable for adaptive headlamps. | Choose only for fixed-VOUT LED strings where VIN remains strictly above or below VOUT, and thermal derating is not required. |
Compared with LTC3789EFE#TRPBF and LM34927QMH/NOPB, the LT8391AEUFD#TRPBF uniquely integrates PWM dimming drive, spread spectrum, and comprehensive LED fault reporting in a single AEC-Q100-qualified device - reducing system complexity and validation effort for automotive lighting OEMs.
Availability
LT8391AEUFD#TRPBF is available at Aetrix Electronics and suitable for automotive headlamps, industrial high-bay lighting, UV-C sterilization modules, and avionics cabin lighting requiring stable component supply, long-term lifecycle support, and AEC-Q100-compliant traceability.
Supply support for LT8391AEUFD#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 industrial, automotive, communications, and healthcare markets since 1965.
The LT8391A product line was developed specifically for high-efficiency, high-frequency LED driver applications demanding seamless buck/boost operation, precise current regulation, and robust fault handling in harsh environments.
FAQ
What is the maximum LED string voltage supported by the LT8391AEUFD#TRPBF?
The LT8391AEUFD#TRPBF supports output voltages up to 60V, with a practical LED string limit of 51V as specified in the datasheet. This enables driving up to 16 white LEDs (3.2V VF each) or 12 UV-C LEDs (4.2V VF each) in series while maintaining regulation margin and thermal safety under worst-case ambient conditions.
Does the LT8391AEUFD#TRPBF require external MOSFETs?
Yes, the LT8391AEUFD#TRPBF is a controller IC and requires four external N-channel MOSFETs (two for buck path, two for boost path), one external high-side PMOS for PWM dimming, plus external inductor, current sense resistors (RSENSE and RLED), and bootstrap capacitors. No power switches are integrated on-die.
How does the LT8391AEUFD#TRPBF handle input voltage transients common in automotive systems?
The LT8391AEUFD#TRPBF tolerates 4V to 56V transient input (per datasheet Absolute Maximum Ratings) and features undervoltage lockout with 1.220V falling threshold and 13mV hysteresis. Its 60V absolute max VIN rating and internal 5V LDO with 160mV dropout allow stable operation during cold-crank (4.5V) and load-dump (overvoltage) events without external protection circuitry.
Can the LT8391AEUFD#TRPBF be synchronized to an external clock?
Yes, the LT8391AEUFD#TRPBF supports external synchronization via the SYNC/SPRD pin. When driven with a TTL/CMOS clock signal between 600kHz and 2.1MHz, it locks its internal oscillator to the external frequency - enabling EMI reduction through frequency dithering or alignment with system master clocks in multi-rail LED systems.
What thermal derating behavior does the LT8391AEUFD#TRPBF provide?
The LT8391AEUFD#TRPBF supports thermal derating via CTRL2 input: applying a negative temperature coefficient voltage (e.g., from NTC divider off VREF) linearly reduces LED current threshold from full scale down to zero over a user-defined temperature range - preventing thermal runaway in enclosed fixtures without adding discrete thermal sensors or microcontrollers.
LT8391AEUFD#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 ~ 125°C (TJ)
- Grade:
- Automotive
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 28-QFN (4x5)
LT8391AEUFD#TRPBF FAQ
1.How can I place an order for LT8391AEUFD#TRPBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LT8391AEUFD#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 LT8391AEUFD#TRPBF reliable?
The price and inventory of LT8391AEUFD#TRPBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LT8391AEUFD#TRPBF is usually 5 days.
3.What payment methods are accepted for LT8391AEUFD#TRPBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LT8391AEUFD#TRPBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LT8391AEUFD#TRPBF?
LT8391AEUFD#TRPBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LT8391AEUFD#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 LT8391AEUFD#TRPBF?
For technical support, including LT8391AEUFD#TRPBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LT8391AEUFD#TRPBF requirements.
6.How does Aetrix verify that LT8391AEUFD#TRPBF is sourced from the original manufacturer or authorized distributors?
All LT8391AEUFD#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 LT8391AEUFD#TRPBF meets industry standards.
7.What is the process for return or replacement of LT8391AEUFD#TRPBF?
All LT8391AEUFD#TRPBF units undergo pre-shipment inspection (PSI). If there is an issue with LT8391AEUFD#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 LT8391AEUFD#TRPBF part is unused and in its original packaging.
Return procedure for LT8391AEUFD#TRPBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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