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Analog Devices Inc. LT8391HFE#TRPBF
- Part No.:
- LT8391HFE#TRPBF
- Manufacturer:
- Analog Devices Inc.
- Category:
- LED Drivers
- Package:
- 28-TSSOP (0.173", 4.40mm Width) Exposed Pad
- Datasheet:
-
LT8391HFE#TRPBF.pdf
- Description:
- IC LED DRIVER CTRLR PWM 28TSSOP
- Quantity:
- Payment:
- Shipping:
Inventory:4,366
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Product details
Overview
LT8391HFE#TRPBF from Analog Devices is a synchronous 4-switch buck-boost LED controller that regulates constant current across VIN (4V–60V) and VOUT (0V–60V), enabling seamless operation in buck, buck-boost, and boost regions. It delivers ±3% LED current accuracy, supports 2000:1 external PWM dimming, and integrates spread-spectrum switching for low EMI - deployed in automotive headlamps and high-power industrial LED lighting.
For engineers reviewing the LT8391HFE#TRPBF datasheet, LT8391HFE#TRPBF pinout, LT8391HFE#TRPBF application, or LT8391HFE#TRPBF equivalent, key selection criteria include its AEC-Q100 qualification, –40°C to 150°C junction temperature rating, 28-lead TSSOP package with exposed pad, and dual analog dimming control via CTRL1/CTRL2 pins for thermal derating and precision current scaling.
Technical Context
The LT8391HFE#TRPBF implements proprietary peak-buck/peak-boost current mode control using a single inductor and shared current sense resistor (LSP/LSN), enabling continuous conduction mode transitions without output voltage discontinuity or audible noise. Its internal 5V LDO (INTVCC) powers gate drivers and logic, while dual error amplifiers regulate both LED current (via ISP/ISN) and output voltage (via FB).
Switching is governed by an adjustable oscillator (150–650 kHz via RT pin) with optional synchronization or ±15% triangle spread spectrum (SYNC/SPRD pin). Fault management includes open/short LED detection with programmable response (hiccup/latch-off/keep-running) via SS pin configuration and FAULT pin reporting.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| VIN Range | 4V to 60V - supports wide-input automotive battery systems (cold crank to load dump) and industrial DC rails. |
| VOUT Range | 0V to 60V - enables direct drive of multi-string LED arrays up to 51V forward voltage without external boost stages. |
| LED Current Accuracy | ±3% at 100mV full scale - ensures consistent luminance across temperature and unit-to-unit variation in high-reliability lighting. |
| Dimming Ratio | 2000:1 external PWM / 128:1 internal PWM - meets flicker-free dimming requirements for automotive adaptive driving beams (ADB). |
| Operating Junction Temp | –40°C to +150°C - qualified per AEC-Q100 Grade H, suitable for under-hood and headlamp module placement. |
| Switching Frequency | 150kHz to 650kHz (adjustable via RT) - allows optimization of magnetics size vs. EMI performance in constrained PCB layouts. |
| Efficiency | Up to 98% at 25V/2A - minimizes thermal load in sealed LED housings and extends system lifetime. |
Pinout & Package
LT8391HFE#TRPBF is housed in a 28-lead plastic TSSOP package with exposed pad (FE package), θJA = 30°C/W, requiring soldering of the exposed pad (Pin 29) to PCB ground for thermal and electrical integrity.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| EN/UVLO | Enable and input undervoltage lockout | Shuts down IC below 0.3V; precise 1.214V falling threshold enables programmable VIN UVLO with hysteresis. |
| ISP / ISN | High-side LED current sense inputs | Kelvin-connected differential pair measuring RLED voltage drop; supports ±3% accuracy and open/short fault detection. |
| CTRL1 / CTRL2 | Analog dimming and thermal derating inputs | Program LED current threshold linearly (0–100mV) or fixed (100mV); CTRL2 enables temperature-dependent current roll-off. |
| PWM / PWMTG | External PWM interface and high-side PMOS driver | PWM accepts 0–2V analog or digital signal; PWMTG drives external PMOS switch with rail-to-rail swing referenced to VOUT. |
| FB | Voltage loop feedback input | Regulates VFB to 1.00V for CV operation and triggers FAULT during open (VFB > 0.95V) or short (VFB < 0.25V) LED conditions. |
| FAULT | Open-drain fault reporting output | Pulled low on LED fault; status updated only during PWM high phase and latched during low phase for synchronized diagnostics. |
| RT / SYNC/SPRD | Oscillator frequency setting and modulation control | RT sets base frequency; SYNC/SPRD selects internal oscillator, external sync clock, or ±15% triangle spread spectrum for EMI reduction. |
| TG1/BG1/TG2/BG2 | N-channel MOSFET gate drivers | Four independent drivers with integrated bootstrap diodes (BST1/BST2) enable synchronous 4-switch topology without external charge pumps. |
Key Features
| Feature | Design Value |
|---|---|
| Proprietary peak-buck/peak-boost control | Enables smooth, low-noise transitions between buck, buck-boost, and boost modes using single inductor and one current sense resistor. |
| Integrated bootstrap diodes (BST1/BST2) | Eliminates need for external Schottky diodes in bootstrap circuits, reducing BOM count and layout complexity. |
| Flicker-free spread spectrum | ±15% triangle modulation reduces peak EMI by >10dB without compromising dimming fidelity or thermal performance. |
| AEC-Q100 Grade H qualification | Validated for automotive applications including headlamps, DRLs, and fog lamps operating up to 150°C junction temperature. |
| Programmable fault response | SS pin resistor selection configures open/short LED behavior as hiccup, latch-off, or keep-running - critical for functional safety compliance. |
Applications
| Automotive Headlamps | Industrial High-Bay Lighting |
|---|---|
Use Scenario: Adaptive front-lighting system (AFS) with matrix LED arrays requiring dynamic current control per segment. IC Role / Device Role / Timing Role: Primary LED current controller managing up to 51V strings with synchronized PWM dimming and thermal derating. Use Value: ±3% current accuracy ensures uniform photometric output across segments; spread spectrum meets CISPR-25 Class 5 EMI limits. |
Use Scenario: 100W+ LED fixture powered from 24V/48V DC industrial bus with variable ambient temperature. IC Role / Device Role / Timing Role: Constant-current buck-boost controller enabling operation across input dips and surges while maintaining lumen stability. Use Value: 4V–60V VIN range tolerates brownouts; 98% efficiency minimizes heatsink size in enclosed fixtures. |
| Off-Road Vehicle Lighting | Emergency Vehicle LED Beacons |
Use Scenario: Ruggedized LED light bars subjected to vibration, wide temperature swings (–40°C to +125°C ambient), and 12V–32V vehicle supply. IC Role / Device Role / Timing Role: Robust LED driver with AEC-Q100 H-grade reliability and open/short LED fault reporting for predictive maintenance. Use Value: –40°C to +150°C junction rating ensures startup at extreme cold; FAULT pin enables CAN bus diagnostic integration. |
Use Scenario: High-intensity rotating/strobing beacon using PWM-modulated LED strings for visibility and signaling compliance. IC Role / Device Role / Timing Role: High-dynamic-range dimming controller supporting 2000:1 external PWM for precise flash timing and intensity grading. Use Value: 2000:1 dimming ratio enables compliant strobe patterns per SAE J1327; no top-MOSFET refresh noise prevents EMI interference with radio receivers. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar LED controller applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LTC3789EFE#TRPBF | 4-switch buck-boost controller without integrated LED-specific features (no ISP/ISN, no PWM dimming, no FAULT reporting) | Designed for general power conversion, not optimized for LED current regulation or automotive lighting diagnostics | Select only if building custom LED current sensing and fault logic externally; lacks native dimming and thermal derating controls. |
| LM3423MH/NOPB | High-side N-channel controller with 100V rating but fixed buck-only topology and no buck-boost capability | Requires separate boost stage for VOUT > VIN; no seamless region transition or spread spectrum EMI reduction | Use only for low-cost, fixed-VIN applications where input never exceeds output; unsuitable for automotive battery voltage variation. |
Compared with LTC3789EFE#TRPBF and LM3423MH/NOPB, the LT8391HFE#TRPBF uniquely integrates LED-specific functions - including dual analog dimming inputs, open/short LED protection with FAULT reporting, and flicker-free spread spectrum - within a single AEC-Q100 qualified buck-boost controller, eliminating external circuitry and reducing system-level validation effort.
Availability
LT8391HFE#TRPBF is available at Aetrix Electronics and suitable for automotive headlamp modules, industrial high-bay LED fixtures, and off-road lighting systems requiring stable component supply, long-term lifecycle support, and AEC-Q100 compliance.
Supply support for LT8391HFE#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 LT8391HFE#TRPBF belongs to Analog Devices' Power by Linear™ LED controller product line, engineered specifically for high-efficiency, high-reliability automotive and industrial LED lighting with integrated diagnostics and EMI mitigation.
FAQ
What is the maximum junction temperature rating for the LT8391HFE#TRPBF?
The LT8391HFE#TRPBF is rated for operation from –40°C to +150°C junction temperature and is qualified per AEC-Q100 Grade H. This specification is explicitly confirmed in the Absolute Maximum Ratings table and Order Information section of the official datasheet, making it suitable for under-hood automotive applications and thermally constrained LED modules where ambient temperatures exceed 125°C.
Does the LT8391HFE#TRPBF support both buck and boost operation from a single inductor?
Yes, the LT8391HFE#TRPBF implements a true 4-switch single-inductor buck-boost topology. Its proprietary peak-buck/peak-boost current mode control enables seamless transitions between buck (VIN > VOUT), buck-boost (VIN ≈ VOUT), and boost (VIN < VOUT) regions without output voltage discontinuity or audible switching artifacts - verified in the Typical Application schematic and Region Transition specifications.
How does the LT8391HFE#TRPBF achieve ±3% LED current accuracy?
The LT8391HFE#TRPBF achieves ±3% LED current accuracy through precision internal references (2.00V VREF, 1.00V FB), matched amplifier gm (2000 µS for LED current amp), and Kelvin-connected ISP/ISN inputs with low offset (±2 mV zero-scale error). This accuracy is guaranteed over the full –40°C to +150°C junction temperature range and confirmed in the Electrical Characteristics table under "Full Scale LED Current Regulation".
Can the LT8391HFE#TRPBF drive a high-side PMOS PWM switch directly?
Yes, the LT8391HFE#TRPBF includes a dedicated PWMTG pin that provides a buffered, inverted version of the PWM input signal with rail-to-rail swing referenced to VOUT (from VOUT–5V to VOUT). This allows direct drive of external high-side PMOS switches without level-shifting circuitry - detailed in the PIN FUNCTIONS section and confirmed by the typical application circuit showing PWMTG connected to a PMOS gate.
What fault protection features are built into the LT8391HFE#TRPBF?
The LT8391HFE#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 status is reported on the open-drain FAULT pin, and response mode (hiccup, latch-off, or keep-running) is configured via resistor selection on the SS pin - all specified in the Electrical Characteristics and Applications Information sections.
LT8391HFE#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 ~ 150°C (TJ)
- Grade:
- Automotive
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 28-TSSOP-EP
LT8391HFE#TRPBF FAQ
1.How can I place an order for LT8391HFE#TRPBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LT8391HFE#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 LT8391HFE#TRPBF reliable?
The price and inventory of LT8391HFE#TRPBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LT8391HFE#TRPBF is usually 5 days.
3.What payment methods are accepted for LT8391HFE#TRPBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LT8391HFE#TRPBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LT8391HFE#TRPBF?
LT8391HFE#TRPBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LT8391HFE#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 LT8391HFE#TRPBF?
For technical support, including LT8391HFE#TRPBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LT8391HFE#TRPBF requirements.
6.How does Aetrix verify that LT8391HFE#TRPBF is sourced from the original manufacturer or authorized distributors?
All LT8391HFE#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 LT8391HFE#TRPBF meets industry standards.
7.What is the process for return or replacement of LT8391HFE#TRPBF?
All LT8391HFE#TRPBF units undergo pre-shipment inspection (PSI). If there is an issue with LT8391HFE#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 LT8391HFE#TRPBF part is unused and in its original packaging.
Return procedure for LT8391HFE#TRPBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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