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Analog Devices Inc. LT8391IFE#TRPBF
- Part No.:
- LT8391IFE#TRPBF
- Manufacturer:
- Analog Devices Inc.
- Category:
- LED Drivers
- Package:
- 28-TSSOP (0.173", 4.40mm Width) Exposed Pad
- Datasheet:
-
LT8391IFE#TRPBF.pdf
- Description:
- IC LED DRIVER CTRLR PWM 28TSSOP
- Quantity:
- Payment:
- Shipping:
Inventory:4,958
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Product details
Overview
LT8391IFE#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, 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 LT8391IFE#TRPBF datasheet, LT8391IFE#TRPBF pinout, LT8391IFE#TRPBF application, or LT8391IFE#TRPBF equivalent, key selection considerations include its seamless buck/buck-boost/boost region transitions, internal/external PWM dimming (128:1 / 2000:1), AEC-Q100 qualification, and 28-lead TSSOP package with exposed pad for thermal management.
Technical Context
The LT8391IFE#TRPBF implements a proprietary dual-mode current sensing architecture: LSP/LSN monitors inductor current for buck/boost boundary detection and peak-current regulation, while ISP/ISN provides direct LED current feedback with 0–100mV full-scale range. Its control logic dynamically selects between peak-buck and peak-boost modes based on VIN/VOUT ratio thresholds (e.g., buck-boost to boost transition at VIN/VOUT = 0.75).
It integrates two independent gate drivers (TG1/BG1 for buck side; TG2/BG2 for boost side), each with 2.6Ω pull-up / 1.4Ω pull-down resistance, and features spread-spectrum operation (±15% triangle modulation) via SYNC/SPRD pin tied to INTVCC - reducing EMI without external clock source.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| VIN Range | 4V to 60V - supports wide-input battery systems including 12V/24V/48V automotive rails and industrial DC supplies. |
| VOUT Range | 0V to 60V - enables single-inductor LED string driving from 1 to 15+ series LEDs (e.g., 51V max LED voltage). |
| LED Current Accuracy | ±3% at 100mV full scale - ensures precise luminance control critical for automotive adaptive lighting compliance. |
| Switching Frequency | 150kHz to 650kHz (adjustable via RT resistor) - allows optimization of magnetics size vs. EMI performance. |
| PWM Dimming Ratio | 2000:1 external / 128:1 internal - supports flicker-free dimming down to 0.05% duty cycle for human-eye-sensitive applications. |
| Operating Temp | –40°C to +125°C junction - qualified for under-hood automotive environments per AEC-Q100 Grade I. |
| Package | 28-lead TSSOP with exposed pad - provides θJC = 5°C/W thermal path for high-power LED driver thermal dissipation. |
Pinout & Package
LT8391IFE#TRPBF is housed in a 28-lead plastic TSSOP package (FE) with exposed pad (Pin 29), which must be soldered to PCB ground for thermal and electrical integrity. θJA = 30°C/W, θJC = 5°C/W.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| ISP / ISN | LED current sense differential inputs | Kelvin-connected to RLED; enable ±3% LED current regulation over temperature and line variations. |
| LSP / LSN | Inductor current sense differential inputs | Provide real-time inductor current for peak-buck/peak-boost mode selection and reverse-current protection. |
| TG1 / BG1 / BST1 / SW1 | Buck-side NMOS gate drivers and switch node | Drive external buck-side FETs; integrated bootstrap diode eliminates external diode requirement. |
| TG2 / BG2 / BST2 / SW2 | Boost-side NMOS gate drivers and switch node | Drive external boost-side FETs; independent bootstrap supply referenced to VOUT. |
| PWMTG | Inverted PWM top-gate driver | Drives external high-side PMOS switch with rail-to-rail swing (VOUT to VOUT–5V), enabling true high-side PWM dimming. |
| CTRL1 / CTRL2 | Analog dimming and thermal derating inputs | Enable 20:1 analog dimming (±3% accuracy) and programmable LED current reduction vs. temperature. |
| FAULT | Open/short LED fault reporting | Open-drain output latched during PWM low; signals VFB overvoltage (>1.05V), open LED (>0.95V & <10mV ISP-ISN), or short LED (<0.25V). |
Key Features
| Feature | Design Value |
|---|---|
| 4-switch single-inductor architecture | Eliminates need for separate buck and boost converters - reduces BOM count, PCB area, and design complexity in wide-VIN LED systems. |
| Proprietary peak-buck/peak-boost control | Enables noiseless transitions between operating regions (e.g., VIN/VOUT = 0.85 → 0.87) without output glitches or current discontinuity. |
| Integrated bootstrap diodes | Removes two external Schottky diodes per channel - simplifies layout, improves reliability, and reduces component cost. |
| Flicker-free spread spectrum | Triangle-modulated ±15% frequency dithering (via SYNC/SPRD tied to INTVCC) lowers peak EMI by >10dB without compromising regulation stability. |
| AEC-Q100 Grade I qualification | Validated for automotive use up to +125°C junction - meets stress test requirements for headlamp, DRL, and fog lamp applications. |
Applications
| Automotive Head Lamps | Industrial High-Bay Lighting |
|---|---|
Use Scenario: Adaptive front-lighting system (AFS) requiring dynamic beam shaping and instant-on/off response across 9–16V battery range. IC Role / Device Role / Timing Role: Primary LED current controller managing 50W+ white LED arrays with synchronized PWM dimming and fault-safe shutdown. Use Value: Seamless buck-boost transitions prevent beam flicker during engine cranking (VIN dip to 6V) or alternator surge (VIN up to 60V). | Use Scenario: 100–200W warehouse lighting powered from 24–48V DC microgrids with DALI or 0–10V analog dimming interface. IC Role / Device Role / Timing Role: Constant-current LED driver core with 20:1 analog dimming (CTRL1/CTRL2) and thermal foldback for fixture longevity. Use Value: ±3% LED current accuracy maintains consistent lumen output across ambient temperatures from –25°C to +70°C. |
| UV-C Sterilization Modules | Emergency Vehicle Lighting |
Use Scenario: Portable UV-C LED array (275nm, 30–50V forward) powered from Li-ion battery packs (10–26V), requiring stable current despite voltage sag. IC Role / Device Role / Timing Role: Wide-input buck-boost controller regulating current through high-VF UV-C strings with open-circuit protection. Use Value: 0–60V VOUT capability accommodates series strings up to 12× UV-C LEDs; FAULT pin triggers safety cutoff on LED open. | Use Scenario: Flashing red/blue LED beacon powered from 12V vehicle bus with EMI-sensitive radio co-location. IC Role / Device Role / Timing Role: High-efficiency (98%) LED driver with spread-spectrum switching and fast PWM dimming for strobe timing. Use Value: ±15% triangle spread spectrum reduces conducted EMI peaks below CISPR 25 Class 5 limits without added filtering. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar LED controller applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LT3965EFE#TRPBF | 4-switch buck-boost LED controller with I²C interface, 12-bit dimming resolution, but fixed 2MHz switching and no spread spectrum. | Requires digital control infrastructure; lacks analog dimming flexibility and EMI-reduction features. | Choose when system-level digital monitoring and addressable channel control are required over analog simplicity and EMI performance. |
| LM3423MH/NOPB | Asynchronous boost-only LED controller (no buck or buck-boost); 65V max VIN; no integrated bootstrap diodes or spread spectrum. | Limited to boost-only topologies; requires external high-side switch for PWM dimming; higher EMI risk. | Choose only for cost-sensitive, fixed-VIN ≥ VLED applications where topology flexibility and EMI are secondary concerns. |
Compared with LT3965EFE#TRPBF and LM3423MH/NOPB, the LT8391IFE#TRPBF uniquely combines wide-input/output range, seamless multi-region operation, analog + PWM dimming, and built-in spread spectrum - making it optimal for automotive and high-reliability industrial LED systems demanding robustness and low EMI.
Availability
LT8391IFE#TRPBF is available at Aetrix Electronics and suitable for automotive headlamps, industrial high-bay lighting, UV-C sterilization modules, and emergency vehicle lighting requiring stable component supply across extended temperature ranges and long production lifecycles.
Supply support for LT8391IFE#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 (DSP) semiconductors, serving precision instrumentation, industrial automation, communications, and automotive markets.
The LT8391IFE#TRPBF belongs to Analog Devices' Power by Linear™ LED controller product line, engineered specifically for high-efficiency, wide-input-range, multi-topology LED drivers in safety-critical and thermally demanding environments.
FAQ
What is the maximum LED string voltage supported by the LT8391IFE#TRPBF?
The LT8391IFE#TRPBF supports an output voltage range of 0V to 60V, with datasheet validation up to 51V LED string voltage. This enables driving up to ~15 white LEDs (3.4V VF each) or ~12 UV-C LEDs (4.2V VF each) in series while maintaining regulation across all operating regions (buck, buck-boost, boost). The 60V absolute maximum rating on VOUT and ISP/ISN pins ensures margin for transients.
Does the LT8391IFE#TRPBF require external bootstrap diodes?
No, the LT8391IFE#TRPBF integrates bootstrap Schottky diodes from INTVCC to both BST1 and BST2 pins, eliminating the need for two external diodes. Each bootstrap capacitor connects directly between BST1 and SW1 (buck side) and BST2 and SW2 (boost side), simplifying layout and improving reliability in high-vibration automotive applications.
How does the LT8391IFE#TRPBF handle LED open-circuit faults?
The LT8391IFE#TRPBF detects open LED conditions when FB voltage exceeds 0.95V *and* ISP–ISN voltage falls below 10mV. Upon detection, it pulls the FAULT pin low (open-drain) and enters a user-selectable fault mode - hiccup (auto-retry), latch-off (shutdown until EN/UVLO reset), or keep-running - configured via resistor on SS pin (e.g., 499kΩ for latch-off).
Can the LT8391IFE#TRPBF operate with input voltage lower than output voltage?
Yes, the LT8391IFE#TRPBF is a true 4-switch buck-boost controller capable of regulating LED current when VIN is below, above, or equal to VOUT. In boost mode (VIN/VOUT < 0.75), it uses TG2/BG2 switches and LSP/LSN sensing; in buck mode (VIN/VOUT > 1.18), it uses TG1/BG1; and in buck-boost mode (0.75 ≤ VIN/VOUT ≤ 1.18), it modulates both switch pairs seamlessly without output disturbance.
What thermal grade does the LT8391IFE#TRPBF support?
The LT8391IFE#TRPBF is rated for operation from –40°C to +125°C junction temperature and is qualified to AEC-Q100 Grade I standards. This makes it suitable for under-hood automotive applications such as headlamps and daytime running lights, where sustained high-temperature operation and reliability under thermal cycling are mandatory.
LT8391IFE#TRPBF Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- -
- Package/Case:
- 28-TSSOP (0.173", 4.40mm Width) 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-TSSOP-EP
LT8391IFE#TRPBF FAQ
1.How can I place an order for LT8391IFE#TRPBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LT8391IFE#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 LT8391IFE#TRPBF reliable?
The price and inventory of LT8391IFE#TRPBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LT8391IFE#TRPBF is usually 5 days.
3.What payment methods are accepted for LT8391IFE#TRPBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LT8391IFE#TRPBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LT8391IFE#TRPBF?
LT8391IFE#TRPBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LT8391IFE#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 LT8391IFE#TRPBF?
For technical support, including LT8391IFE#TRPBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LT8391IFE#TRPBF requirements.
6.How does Aetrix verify that LT8391IFE#TRPBF is sourced from the original manufacturer or authorized distributors?
All LT8391IFE#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 LT8391IFE#TRPBF meets industry standards.
7.What is the process for return or replacement of LT8391IFE#TRPBF?
All LT8391IFE#TRPBF units undergo pre-shipment inspection (PSI). If there is an issue with LT8391IFE#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 LT8391IFE#TRPBF part is unused and in its original packaging.
Return procedure for LT8391IFE#TRPBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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