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Analog Devices Inc. LT8391HUFD#PBF
- Part No.:
- LT8391HUFD#PBF
- Manufacturer:
- Analog Devices Inc.
- Category:
- LED Drivers
- Package:
- 28-WFQFN Exposed Pad
- Datasheet:
-
LT8391HUFD#PBF.pdf
- Description:
- IC LED DRIVER CTRLR PWM 28QFN
- Quantity:
- Payment:
- Shipping:
Inventory:4,335
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Product details
Overview
LT8391HUFD#PBF from Analog Devices is a synchronous 4-switch buck-boost LED controller with peak-buck/peak-boost current mode control, 4V–60V input and 0V–60V output capability, ±3% LED current accuracy at 100mV full scale, and AEC-Q100 qualification for automotive headlamp and high-power lighting systems.
For engineers reviewing the LT8391HUFD#PBF datasheet, LT8391HUFD#PBF pinout, LT8391HUFD#PBF application, or LT8391HUFD#PBF equivalent, key selection considerations include its seamless buck/buck-boost/boost region transitions, integrated bootstrap diodes, spread-spectrum EMI reduction, high-side PMOS PWM switch driver (PWMTG), and fault reporting via open/short LED detection.
Technical Context
The LT8391HUFD#PBF implements a proprietary dual-mode current sensing architecture that monitors inductor current via LSP/LSN in all operating regions and LED current via ISP/ISN for regulation and fault detection. Its control logic dynamically selects between peak-buck and peak-boost modes based on VIN/VOUT ratio thresholds (e.g., buck-boost to boost at VIN/VOUT = 0.75).
It integrates two independent gate drivers (TG1/BG1 for buck side; TG2/BG2 for boost side), internal 5V INTVCC LDO, 2V VREF reference, and analog dimming inputs (CTRL1/CTRL2) enabling 20:1 linear dimming with thermal derating support. The RP and RT pins configure internal PWM dimming frequency (up to 4096× switching frequency ratio) and oscillator frequency (150–650 kHz), respectively.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 4V to 60V - supports wide automotive battery transients and industrial DC rails without external pre-regulation. |
| Output Voltage Range | 0V to 60V - enables direct drive of multi-string LED arrays up to 51V forward voltage. |
| LED Current Accuracy | ±3% at 100mV full scale - ensures consistent luminance across temperature and line/load variations. |
| Switching Frequency | 150kHz to 650kHz adjustable via RT resistor - allows optimization of efficiency vs. size and EMI compliance. |
| Dimming Ratio | 2000:1 external PWM, 128:1 internal PWM - delivers flicker-free dimming down to 0.05% duty cycle. |
| Operating Junction Temp | –40°C to +150°C - qualified for under-hood automotive applications per AEC-Q100 Grade H. |
| 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. |
Pinout & Package
LT8391HUFD#PBF uses a 28-lead plastic QFN package (4mm × 5mm) with exposed thermal pad (Pin 29 = GND). The package supports high-current gate drive and efficient heat dissipation in compact LED driver layouts.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| VIN | Input supply rail | Primary power source determining buck/buck-boost/boost operating region; requires ≥1µF local ceramic bypass. |
| VOUT | Output supply rail | Defines output voltage boundary; serves as positive rail for PWMTG high-side PMOS driver. |
| ISP / ISN | LED current sense differential inputs | Kelvin-connected to RLED for precise LED current regulation and open/short fault detection. |
| LSP / LSN | Inductor current sense differential inputs | Kelvin-connected to RSENSE for peak-buck/peak-boost current mode control across all regions. |
| TG1 / BG1 / BST1 / SW1 | Buck-side N-MOSFET gate drives and node | Drive external buck-side FETs; BST1 includes integrated Schottky diode for bootstrap charging. |
| TG2 / BG2 / BST2 / SW2 | Boost-side N-MOSFET gate drives and node | Drive external boost-side FETs; BST2 includes integrated Schottky diode for bootstrap charging. |
| PWMTG | High-side PMOS PWM switch driver | Inverted buffered PWM output driving external PMOS; swing from (VOUT – 5V) to VOUT. |
| CTRL1 / CTRL2 | Analog dimming and thermal derating inputs | Enable 20:1 linear dimming and programmable current derating vs. temperature using resistor dividers from VREF. |
| FAULT | Open-drain fault reporting output | Pulled low during open LED (VFB > 0.95V & V(ISP-ISN) < 10mV) or short LED (VFB < 0.25V); requires external pull-up. |
| SS | Soft-start timer capacitor connection | Charged by internal 12.5µA current; sets soft-start time and configures fault response (hiccup/latchoff/run) via resistor to VREF. |
Key Features
| Feature | Design Value |
|---|---|
| 4-switch single-inductor architecture | Eliminates need for separate buck and boost converters; enables seamless VIN-above/VOUT, VIN-below/VOUT, and VIN-near-VOUT operation. |
| Integrated bootstrap diodes | Reduces BOM count and layout complexity by embedding Schottky diodes for BST1/BST2 charge paths. |
| Flicker-free spread spectrum | ±15% triangle modulation around switching frequency reduces peak EMI by >10dB without compromising regulation stability. |
| No top MOSFET refresh noise | Proprietary gate timing eliminates audible noise during buck or boost transitions, critical for automotive cabin environments. |
| AEC-Q100 Grade H qualification | Validated for operation from –40°C to +150°C junction temperature, meeting automotive reliability and stress test requirements. |
Applications
| Automotive Head Lamps | Industrial High-Bay Lighting |
|---|---|
Use Scenario: Adaptive front-lighting system (AFS) requiring dynamic beam shaping and high-lumen output across 9–16V battery range with cold-crank tolerance. IC Role / Device Role / Timing Role: Primary LED current controller managing 4-switch topology to maintain constant 2A string current despite VIN dropping to 4V during cranking. Use Value: Seamless region transition prevents light flicker during engine start; ±3% current accuracy ensures consistent photometric output across temperature. | Use Scenario: 50W+ LED retrofit for warehouse high-bay fixtures powered from 24–48V DC microgrids with variable load conditions. IC Role / Device Role / Timing Role: Synchronous buck-boost LED driver regulating current into 40V LED strings while accepting input from rectified AC or PoE-derived DC rails. Use Value: 98% peak efficiency minimizes thermal load in enclosed fixtures; 2000:1 PWM dimming enables DALI-compatible smooth dimming down to 0.1%. |
| Off-Road Vehicle Lighting | UV-C Disinfection Systems |
Use Scenario: Ruggedized LED work lights for construction equipment operating in 12V/24V dual-battery systems with high EMI immunity requirements. IC Role / Device Role / Timing Role: LED controller implementing spread-spectrum switching and fault latching to survive vibration, load dump, and reverse polarity events. Use Value: Integrated open/short LED protection prevents thermal runaway; AEC-Q100 qualification ensures long-term reliability in harsh environments. | Use Scenario: Pulsed UV-C LED arrays requiring precise current control and fast PWM dimming for germicidal dose modulation. IC Role / Device Role / Timing Role: Constant-current driver delivering 1.5A pulses at 100kHz with sub-100ns PWM-to-PWMTG propagation delay for accurate pulse-width control. Use Value: PWMTG driver supports high-side PMOS switching with 5V gate swing margin, enabling reliable turn-on of UV-C LEDs with high VF. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar LED controller applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LTC3789IUFD#PBF | 4-switch buck-boost controller without integrated LED-specific features: no ISP/ISN sense, no PWMTG driver, no LED fault reporting, no analog dimming inputs. | Designed for general DC/DC conversion, not optimized for constant-current LED regulation or automotive lighting safety monitoring. | Select only if building non-LED power supplies or adding external current sensing and fault logic. |
| LM3423MH/NOPB | High-side N-channel controller with external PWM dimming only; lacks buck-boost capability, spread spectrum, and integrated bootstrap diodes. | Requires external boost converter for VIN < VOUT; limited to 42V max input; no AEC-Q100 qualification. | Consider for cost-sensitive 12V-only LED applications where VIN never drops below VOUT and automotive qualification is unnecessary. |
Compared with LTC3789IUFD#PBF and LM3423MH/NOPB, the LT8391HUFD#PBF delivers integrated LED-specific functionality-including ISP/ISN current sensing, PWMTG driver, open/short LED fault reporting, and AEC-Q100 qualification-enabling faster design cycles and higher reliability in automotive and industrial LED lighting.
Availability
LT8391HUFD#PBF is available at Aetrix Electronics and suitable for automotive headlamps, industrial high-bay lighting, off-road vehicle lighting, and UV-C disinfection systems requiring stable component supply, AEC-Q100 compliance, and high-efficiency buck-boost LED regulation.
Supply support for LT8391HUFD#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 precision instrumentation, industrial automation, communications, and automotive markets.
The LT8391 product line was designed specifically for high-reliability, high-efficiency LED driver applications in automotive and industrial environments, emphasizing seamless region transitions, low EMI, and robust fault protection.
FAQ
What is the maximum LED string voltage supported by the LT8391HUFD#PBF?
The LT8391HUFD#PBF supports an output voltage range of 0V to 60V, with a specified 51V LED string rating. This allows direct drive of multi-series white or UV-C LED strings without cascaded converters, provided the total forward voltage remains within the 60V absolute maximum and thermal limits of the external MOSFETs and layout.
Does the LT8391HUFD#PBF require external bootstrap diodes?
No, the LT8391HUFD#PBF integrates Schottky bootstrap diodes from INTVCC to BST1 and BST2. External bootstrap capacitors (typically 0.1µF ceramic) must still be placed between BST1–SW1 and BST2–SW2, but discrete diodes are eliminated, reducing component count and board area.
How does the LT8391HUFD#PBF handle transitions between buck, buck-boost, and boost modes?
The LT8391HUFD#PBF uses proprietary peak-buck/peak-boost current mode control with predefined VIN/VOUT ratio thresholds (e.g., buck-boost to boost at 0.75, boost to buck-boost at 0.85) to switch modes seamlessly. Transitions occur without output disturbance or audible noise, maintaining continuous LED current regulation throughout.
Can the LT8391HUFD#PBF be used for constant-voltage applications?
Yes - the LT8391HUFD#PBF supports constant-voltage regulation via the FB pin, which regulates to 1.00V with ±0.5% line/load regulation. While primarily optimized for constant-current LED driving, it can regulate output voltage in battery charging or auxiliary supply applications when configured with appropriate feedback resistors and current-limiting safeguards.
What fault protection mechanisms are built into the LT8391HUFD#PBF?
The LT8391HUFD#PBF provides open LED detection (VFB > 0.95V & V(ISP-ISN) < 10mV), short LED detection (VFB < 0.25V), overvoltage protection (VFB > 1.05V), and thermal shutdown. Fault status is reported on the open-drain FAULT pin, and response mode (hiccup, latch-off, or keep-running) is configurable via the SS pin resistor network.
LT8391HUFD#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:
- 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#PBF FAQ
1.How can I place an order for LT8391HUFD#PBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LT8391HUFD#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 LT8391HUFD#PBF reliable?
The price and inventory of LT8391HUFD#PBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LT8391HUFD#PBF is usually 5 days.
3.What payment methods are accepted for LT8391HUFD#PBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LT8391HUFD#PBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LT8391HUFD#PBF?
LT8391HUFD#PBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LT8391HUFD#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 LT8391HUFD#PBF?
For technical support, including LT8391HUFD#PBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LT8391HUFD#PBF requirements.
6.How does Aetrix verify that LT8391HUFD#PBF is sourced from the original manufacturer or authorized distributors?
All LT8391HUFD#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 LT8391HUFD#PBF meets industry standards.
7.What is the process for return or replacement of LT8391HUFD#PBF?
All LT8391HUFD#PBF units undergo pre-shipment inspection (PSI). If there is an issue with LT8391HUFD#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 LT8391HUFD#PBF part is unused and in its original packaging.
Return procedure for LT8391HUFD#PBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
LT8391HUFD#PBF Tags
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