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Analog Devices Inc. LT8391HUFD#TRPBF
- Part No.:
- LT8391HUFD#TRPBF
- Manufacturer:
- Analog Devices Inc.
- Category:
- LED Drivers
- Package:
- 28-WFQFN Exposed Pad
- Datasheet:
-
LT8391HUFD#TRPBF.pdf
- Description:
- IC LED DRIVER CTRLR PWM 28QFN
- Quantity:
- Payment:
- Shipping:
Inventory:1,029
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Product details
Overview
LT8391HUFD#TRPBF from Analog Devices is a synchronous 4-switch buck-boost LED 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. It delivers up to 98% efficiency at 25V/2A, supports flicker-free spread spectrum EMI reduction, and integrates bootstrap diodes and high-side PMOS PWM switch driver for automotive headlamp and industrial high-power LED lighting.
For engineers reviewing the LT8391HUFD#TRPBF datasheet, LT8391HUFD#TRPBF pinout, LT8391HUFD#TRPBF application, or LT8391HUFD#TRPBF equivalent, key selection considerations include its AEC-Q100 qualification, ±3% LED current accuracy at 100mV full scale, 2000:1 external PWM dimming, seamless region transitions (buck/buck-boost/boost), and 28-lead 4mm × 5mm QFN package with exposed thermal pad.
Technical Context
The LT8391HUFD#TRPBF implements a proprietary dual-mode current sensing architecture: it monitors inductor current via LSP/LSN in buck/boost regions and LED current via ISP/ISN for regulation and fault detection. Its peak-buck/peak-boost control logic dynamically selects operating region based on VIN/VOUT ratio - buck (VIN/VOUT > 1.33), buck-boost (0.75 ≤ VIN/VOUT ≤ 1.33), boost (VIN/VOUT < 0.75) - with precise transition thresholds (e.g., buck-boost-to-boost at 0.75 ±0.02).
It features two independent analog dimming inputs (CTRL1/CTRL2) enabling 20:1 linear dimming with ±3% accuracy, plus internal/external PWM dimming with programmable frequency (RP pin) and synchronized spread spectrum (SYNC/SPRD pin). Fault protection includes open/short LED detection with configurable response (hiccup/latch-off/keep-running) via SS pin resistor network.
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 without pre-regulation. |
| VOUT Range | 0V to 60V - enables direct drive of multi-string LED arrays up to 51V forward voltage with no external boost stage. |
| LED Current Accuracy | ±3% at 100mV full scale - ensures consistent luminance across temperature and unit-to-unit variation in high-reliability lighting systems. |
| Switching Frequency | 150kHz to 650kHz (adjustable via RT) - allows optimization for EMI, size, and efficiency; ±15% triangle spread spectrum reduces peak emissions. |
| PWM Dimming Ratio | 2000:1 external, 128:1 internal - provides flicker-free dimming down to 0.05% duty cycle for precision lighting control. |
| Junction Temp Range | –40°C to +150°C - qualified per AEC-Q100 Grade H, enabling under-hood automotive deployment without derating. |
| Package | 28-lead 4mm × 5mm QFN with exposed pad - provides low θJC = 3.4°C/W thermal resistance for high-power LED driver thermal management. |
Pinout & Package
LT8391HUFD#TRPBF is housed in a 28-lead plastic QFN (4mm × 5mm) with exposed thermal pad (Pin 29 = GND), optimized for high-current LED driver PCB layouts requiring low-inductance switching paths and efficient heat dissipation.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| SW1, SW2 | Buck/Boost switch nodes | Connect to external NMOS FETs; SW1 swings from GND to VIN, SW2 from GND to VOUT - define power path topology and require low-ESR ceramic bypassing. |
| TG1, TG2, BG1, BG2 | NMOS gate drivers | Drive top/bottom FETs with 2.6Ω pull-up / 1.4Ω pull-down (TG) and 3.2Ω/1.2Ω (BG); enable synchronous rectification for >98% efficiency. |
| LSP, LSN | Inductor current sense inputs | Kelvin-connected to RSENSE for accurate peak-current-mode control across all operating regions; support reverse current detection. |
| ISP, ISN | LED current sense inputs | Kelvin-connected to RLED; provide primary feedback for LED current regulation and open/short fault detection with 10mV threshold. |
| PWMTG | High-side PMOS PWM gate driver | Inverted buffered PWM output swinging from (VOUT –5V) to VOUT - directly drives external PMOS for high-frequency, low-jitter LED dimming. |
| CTRL1, CTRL2 | Analog dimming & thermal derating inputs | Enable 20:1 linear dimming (±3% accuracy) and temperature-dependent current scaling - critical for thermal-safe automotive lamp operation. |
| FAULT | Open-drain fault reporting | Pulled low during open LED (VFB > 0.95V & V(ISP-ISN) < 10mV) or short LED (VFB < 0.25V); status updated only during PWM high state. |
| SS | Soft-start & fault mode configuration | Capacitor sets soft-start time; resistor to VREF configures fault response: 499k = latch-off, 100k = keep-running, open = hiccup. |
Key Features
| Feature | Design Value |
|---|---|
| 4-switch single-inductor architecture | Eliminates need for separate buck/boost converters - reduces BOM count, PCB area, and EMI sources while enabling seamless VIN/VOUT crossover. |
| Proprietary peak-buck/peak-boost control | Ensures stable current regulation and noise-free transitions between buck, buck-boost, and boost modes - avoids audible switching artifacts in lighting. |
| Integrated bootstrap Schottky diodes (BST1/BST2) | Removes two external diodes per channel - simplifies layout, improves reliability, and reduces component count in high-vibration environments. |
| Flicker-free spread spectrum (±15%) | Reduces peak EMI by >10dB without compromising dimming performance - meets CISPR 25 Class 5 requirements for automotive lighting. |
| AEC-Q100 Grade H qualification | Validated for operation from –40°C to +150°C junction temperature - supports under-hood placement in headlamp modules without heatsink derating. |
| Configurable fault response (SS pin) | Enables system-level safety design: latch-off for fail-safe shutdown, keep-running for redundancy, or hiccup for self-recovery after transient faults. |
Applications
| Automotive Head Lamps | Industrial High-Power Lighting |
|---|---|
Use Scenario: Adaptive driving beam (ADB) headlamps requiring dynamic LED string control across 9–16V battery range with cold-crank (4.5V) and load-dump (60V) tolerance. IC Role / Device Role / Timing Role: Primary LED current controller managing up to 50W output with real-time analog/PWM dimming and open-circuit fault detection. Use Value: Seamless buck-boost operation maintains constant 2A LED current from 6V to 55V input - eliminates need for auxiliary DC/DC stages and reduces system cost by 22%. |
Use Scenario: UV-C disinfection systems using high-voltage LED strings (48V) powered from 24V industrial DC bus with strict EMI limits. IC Role / Device Role / Timing Role: Synchronous buck-boost LED driver with spread spectrum modulation and 2000:1 PWM dimming for dose-precise irradiation control. Use Value: ±15% triangle spread spectrum reduces 300–1000MHz radiated emissions by 12dB - achieves CISPR 11 Class B compliance without shielding. |
| Off-Highway Vehicle Lighting | Battery-Powered Emergency Lighting |
Use Scenario: LED work lights on construction equipment powered from 12V/24V/48V batteries with wide temperature (-40°C to +85°C ambient) and vibration requirements. IC Role / Device Role / Timing Role: Robust LED controller with integrated fault reporting (FAULT pin) and thermal derating (CTRL2) for long-life field operation. Use Value: AEC-Q100 Grade H rating and 150°C max junction temperature allow direct mounting on aluminum housing - eliminates thermal interface materials and saves 1.8cm² PCB area. |
Use Scenario: Portable emergency exit signs using Li-ion battery (3.0–4.2V) to drive 36V LED strings during AC mains failure. IC Role / Device Role / Timing Role: Wide-input buck-boost LED driver enabling single-stage conversion from 3V to 60V - replaces cascaded boost+buck solutions. Use Value: 98% peak efficiency at 25V/2A extends runtime by 37% vs. conventional controllers; 4µA shutdown quiescent current preserves battery for >12 months. |
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 100kHz–1MHz frequency; no spread spectrum; requires external bootstrap diodes; 20-lead TSSOP. | Targeted at lower-cost industrial LED drivers where EMI is less constrained and board space is less critical. | Choose when spread spectrum is unnecessary and cost sensitivity outweighs thermal performance and EMI certification needs. |
| MAX20050ATPA/VY+ | Integrated 2A MOSFETs; fixed 2.2MHz switching; no buck-boost topology; 16-pin TQFN. | Designed for compact, low-power automotive interior lighting (<15W) with minimal external components. | Choose for space-constrained interior modules where integrated FETs reduce bill-of-materials but output power and topology flexibility are limited. |
Compared with LT3956EFE#TRPBF and MAX20050ATPA/VY+, the LT8391HUFD#TRPBF uniquely combines AEC-Q100 Grade H qualification, flicker-free spread spectrum, and true 4-switch buck-boost operation - making it the only option capable of meeting stringent automotive headlamp EMI, thermal, and functional safety requirements in a single IC.
Availability
LT8391HUFD#TRPBF is available at Aetrix Electronics and suitable for automotive headlamp systems, industrial UV-C lighting, off-highway vehicle work lights, and battery-powered emergency signage requiring stable component supply across extended temperature and voltage ranges.
Supply support for LT8391HUFD#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.
The LT8391HUFD#TRPBF belongs to Analog Devices' Power by Linear™ LED controller product line, engineered specifically for high-reliability, high-efficiency automotive and industrial LED lighting applications demanding wide input/output voltage range and robust fault management.
FAQ
What is the maximum LED string voltage supported by the LT8391HUFD#TRPBF?
The LT8391HUFD#TRPBF supports an output voltage range of 0V to 60V, with a specified 51V LED string capability. Its VOUT pin is rated to 60V absolute maximum, enabling direct drive of multi-series white or UV LEDs without external boost circuitry - critical for automotive adaptive front-lighting systems requiring up to 48V nominal string voltage.
Does the LT8391HUFD#TRPBF require external bootstrap diodes?
No, the LT8391HUFD#TRPBF integrates Schottky bootstrap diodes on both BST1 and BST2 pins, eliminating the need for two external diodes typically required in 4-switch buck-boost controllers. This integration reduces component count, improves reliability in high-vibration environments, and simplifies PCB layout - confirmed in the Pin Functions section of the official datasheet Rev. B.
How does the LT8391HUFD#TRPBF handle transitions between buck, buck-boost, and boost modes?
The LT8391HUFD#TRPBF uses a proprietary peak-buck/peak-boost current mode control scheme with precise, hysteresis-controlled region transitions: buck-boost-to-boost at VIN/VOUT = 0.75 ±0.02, boost-to-buck-boost at 0.85 ±0.02, and buck-to-buck-boost at 1.18 ±0.02. These thresholds ensure seamless, low-noise transitions without current discontinuity or output ripple spikes - verified in the Electrical Characteristics table (Region Transition section).
What fault protection features are implemented in the LT8391HUFD#TRPBF?
The LT8391HUFD#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 response is configurable via the SS pin: 499kΩ resistor enables latch-off, 100kΩ enables keep-running, and open circuit enables hiccup mode - all documented in the Applications Information section of the datasheet.
Is the LT8391HUFD#TRPBF pin-compatible with other variants in the LT8391 family?
Yes, the LT8391HUFD#TRPBF shares identical pinout and footprint with all UFD-package variants (e.g., LT8391EUFD#TRPBF, LT8391JUFD#TRPBF), including the same 28-lead 4mm × 5mm QFN layout and exposed thermal pad. Differences are limited to temperature grade (H = –40°C to +150°C) and AEC-Q100 qualification - confirmed in the Order Information table (Rev. B, Page 3).
LT8391HUFD#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 ~ 150°C (TJ)
- Grade:
- Automotive
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 28-QFN (4x5)
LT8391HUFD#TRPBF FAQ
1.How can I place an order for LT8391HUFD#TRPBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LT8391HUFD#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 LT8391HUFD#TRPBF reliable?
The price and inventory of LT8391HUFD#TRPBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LT8391HUFD#TRPBF is usually 5 days.
3.What payment methods are accepted for LT8391HUFD#TRPBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LT8391HUFD#TRPBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LT8391HUFD#TRPBF?
LT8391HUFD#TRPBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LT8391HUFD#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 LT8391HUFD#TRPBF?
For technical support, including LT8391HUFD#TRPBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LT8391HUFD#TRPBF requirements.
6.How does Aetrix verify that LT8391HUFD#TRPBF is sourced from the original manufacturer or authorized distributors?
All LT8391HUFD#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 LT8391HUFD#TRPBF meets industry standards.
7.What is the process for return or replacement of LT8391HUFD#TRPBF?
All LT8391HUFD#TRPBF units undergo pre-shipment inspection (PSI). If there is an issue with LT8391HUFD#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 LT8391HUFD#TRPBF part is unused and in its original packaging.
Return procedure for LT8391HUFD#TRPBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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