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Analog Devices Inc. LT8391EFE#TRPBF
- Part No.:
- LT8391EFE#TRPBF
- Manufacturer:
- Analog Devices Inc.
- Category:
- LED Drivers
- Package:
- 28-TSSOP (0.173", 4.40mm Width) Exposed Pad
- Datasheet:
-
LT8391EFE#TRPBF.pdf
- Description:
- IC LED DRIVER CTRLR PWM 28TSSOP
- Quantity:
- Payment:
- Shipping:
Inventory:3,410
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Product details
Overview
LT8391EFE#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 ±3% LED current accuracy at 100mV full scale, supports 150kHz–650kHz adjustable switching frequency with spread spectrum EMI reduction, and enables 2000:1 external PWM dimming - ideal for automotive headlamps and high-power industrial LED drivers.
For engineers reviewing the LT8391EFE#TRPBF datasheet, LT8391EFE#TRPBF pinout, LT8391EFE#TRPBF application, or LT8391EFE#TRPBF equivalent, key selection criteria include its seamless buck/buck-boost/boost region transitions, integrated bootstrap diodes, AEC-Q100 qualification (Grade E), 28-lead TSSOP package with exposed pad, and fault reporting for open/short LED conditions.
Technical Context
The LT8391EFE#TRPBF implements a proprietary dual-mode current sensing architecture: LSP/LSN senses inductor current for peak-buck (VIN < VOUT) and peak-boost (VIN > VOUT) control, while ISP/ISN directly measures LED current with Kelvin sensing. Its control logic dynamically selects operating region based on real-time 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), each with matched rise/fall times (25ns/20ns), and features synchronized soft-start via SS pin with programmable fault response (hiccup/latch-off/keep-running) using resistor-to-VREF configuration.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| VIN Range | 4V to 60V - supports wide-input automotive battery (9V–16V nominal) and industrial 24V/48V rails without pre-regulation. |
| VOUT 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 pin) - 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 architectural lighting. |
| Operating Temp | –40°C to +125°C junction - validated for under-hood automotive placement per AEC-Q100 Grade E. |
| Fault Protection | Open LED (VFB > 0.95V & V(ISP-ISN) < 10mV), short LED (VFB < 0.25V) - latched or retry behavior configurable via SS pin resistor. |
Pinout & Package
LT8391EFE#TRPBF is housed in a 28-lead plastic TSSOP package with exposed thermal pad (Pin 29 = GND), optimized for high-power LED driver PCB layouts requiring low θJA (30°C/W) and robust thermal dissipation.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| ISP / ISN | LED current sense differential inputs | Kelvin-connected to RLED for ±3% accuracy; common-mode range 0V–60V enables high-side or low-side sensing. |
| LSP / LSN | Inductor current sense differential inputs | Directly monitors single inductor current in all three regions (buck/buck-boost/boost) for seamless transitions. |
| TG1 / BG1 / TG2 / BG2 | N-channel MOSFET gate drivers | Independent top/bottom drives per side; 2.6Ω pull-up / 1.4Ω pull-down resistance minimizes switching losses. |
| BST1 / BST2 | Bootstrap floating supplies | Integrated Schottky diodes charge external capacitors; swing from INTVCC to (VIN+INTVCC) or (VOUT+INTVCC). |
| PWMTG | Inverted PWM top-gate driver | Drives external high-side PMOS switch with rail-to-rail swing (VOUT to VOUT–5V); eliminates refresh noise. |
| CTRL1 / CTRL2 | Analog dimming & thermal derating inputs | 20:1 analog dimming (±3% accuracy) and programmable thermal foldback via negative tempco resistor divider. |
| SYNC/SPRD | Frequency sync or spread-spectrum enable | Tie to INTVCC for ±15% triangle spread spectrum; ground for fixed frequency; apply external clock for synchronization. |
Key Features
| Feature | Design Value |
|---|---|
| 4-switch single-inductor topology | Eliminates need for separate buck/boost converters; reduces BOM count and PCB area by 40% vs. dual-stage solutions. |
| Proprietary peak-buck/peak-boost control | Ensures continuous conduction mode and <100µs transition time between regions without output disturbance. |
| Integrated bootstrap diodes | Removes two external Schottky diodes per side, simplifying layout and improving reliability in high-vibration environments. |
| No top MOSFET refresh noise | Eliminates audible noise and EMI spikes during buck/boost transitions - critical for automotive cabin applications. |
| AEC-Q100 Grade E qualification | Validated for automotive headlamp systems including temperature cycling, HTOL, and ESD testing per stress test plan. |
Applications
| Automotive Head Lamps | Industrial High-Bay Lighting |
|---|---|
Use Scenario: Adaptive front-lighting system (AFS) with matrix LED arrays requiring precise current regulation across 9V–16V battery input and 30V–48V LED string voltage. IC Role / Device Role / Timing Role: Primary LED current controller managing four-quadrant power flow; handles cold-crank (4.5V) and load-dump (60V) transients without shutdown. Use Value: Seamless region transitions prevent visible light flicker during vehicle acceleration/deceleration; ±3% current accuracy maintains beam pattern consistency. | Use Scenario: 100W+ warehouse lighting fixture powered from 24VDC or 48VDC industrial bus, dimmed via DALI or 0–10V interface. IC Role / Device Role / Timing Role: Constant-current LED driver with analog/PWM hybrid dimming; uses CTRL1/CTRL2 for 20:1 analog dimming and thermal derating. Use Value: 98% peak efficiency reduces heatsink size; 2000:1 external PWM dimming enables smooth 0.1%–100% intensity control without color shift. |
| Off-Road Vehicle Lighting | Battery-Powered Emergency Lighting |
Use Scenario: LED work lights on construction equipment operating from 12V/24V lead-acid batteries with wide voltage sag (6V–32V). IC Role / Device Role / Timing Role: Buck-boost LED controller maintaining 2A constant current despite deep discharge; uses spread spectrum to pass CISPR-25 Class 5 EMI limits. Use Value: Integrated fault reporting (FAULT pin) triggers system-level diagnostics for open/short LED detection; AEC-Q100 qualification ensures vibration resilience. | Use Scenario: Portable emergency egress lighting powered by Li-ion battery pack (8.4V–12.6V), requiring >5-hour runtime at full brightness and low quiescent current in standby. IC Role / Device Role / Timing Role: High-efficiency LED driver with 2.1µA VIN quiescent current in shutdown (EN/UVLO < 0.3V) and 270µA in idle state. Use Value: 4V minimum VIN enables operation down to nearly depleted battery; soft-start (SS pin) prevents inrush current damage to battery protection circuitry. |
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; supports up to 8-bit digital dimming and fault logging; no spread spectrum; 3.5V–60V VIN. | Requires microcontroller host for configuration; better suited for smart lighting systems needing telemetry vs. standalone analog control. | Select when digital control, fault history, or multi-channel synchronization is required; not drop-in due to different pinout and communication protocol. |
| LM34927QMH/NOPB | 2-switch buck-boost LED controller (no boost-side bottom switch); 4.5V–65V VIN; fixed 2.5A peak switch current; no integrated bootstrap diodes. | Limited to lower-power applications (<30W); requires external bootstrap diodes and cannot regulate LED current when VIN ≈ VOUT. | Select for cost-sensitive, lower-power designs where seamless VIN=VOUT operation is unnecessary and discrete bootstrap components are acceptable. |
Compared with LT3965EFE#TRPBF and LM34927QMH/NOPB, the LT8391EFE#TRPBF uniquely combines analog-dimming simplicity, spread-spectrum EMI reduction, and true VIN=VOUT regulation - making it optimal for automotive and industrial LED drivers demanding robustness and flicker-free performance without MCU dependency.
Availability
LT8391EFE#TRPBF is available at Aetrix Electronics and suitable for automotive headlamps, industrial high-bay lighting, off-road vehicle lighting, and battery-powered emergency lighting requiring stable component supply and long-term production continuity.
Supply support for LT8391EFE#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 semiconductor leader specializing in high-performance analog, mixed-signal, and digital signal processing technologies for precision instrumentation, industrial automation, and automotive safety systems.
The LT8391 product line was designed specifically for high-reliability, high-efficiency LED driver applications in harsh environments - emphasizing seamless buck/buck-boost/boost transitions, AEC-Q100 compliance, and integrated EMI mitigation.
FAQ
What is the maximum LED string voltage supported by the LT8391EFE#TRPBF?
The LT8391EFE#TRPBF supports an output voltage range of 0V to 60V, enabling direct drive of LED strings up to 51V forward voltage as specified in the datasheet. This capability is achieved through its synchronous 4-switch architecture and integrated gate drivers rated for 60V operation on VOUT, SW2, and BST2 pins - making LT8391EFE#TRPBF suitable for multi-series white LED arrays in automotive and industrial lighting.
How does the LT8391EFE#TRPBF handle transitions between buck, buck-boost, and boost operating regions?
The LT8391EFE#TRPBF uses a proprietary peak-buck/peak-boost current mode control scheme that continuously monitors the VIN/VOUT ratio and switches regions seamlessly without output disturbance. Transition thresholds are precisely defined: buck-boost to boost at VIN/VOUT = 0.75, boost to buck-boost at 0.85, buck to buck-boost at 1.18, and buck-boost to buck at 1.33 - ensuring stable LED current regulation across all input-output conditions in LT8391EFE#TRPBF-based designs.
Can the LT8391EFE#TRPBF be used in AEC-Q100 qualified automotive applications?
Yes, the LT8391EFE#TRPBF is AEC-Q100 qualified for automotive applications (Grade E, –40°C to +125°C junction temperature). It undergoes rigorous stress testing including temperature cycling, high-temperature operating life (HTOL), and ESD per AEC-Q100-002/004 standards - validating its suitability for under-hood and exterior lighting systems such as headlamps and DRLs where LT8391EFE#TRPBF's fault reporting and spread-spectrum EMI reduction are critical.
What is the purpose of the PWMTG pin on the LT8391EFE#TRPBF, and how is it used?
The PWMTG pin on the LT8391EFE#TRPBF provides an inverted, buffered version of the PWM input signal to drive an external high-side PMOS switch. It swings from VOUT down to (VOUT – 5V) and up to VOUT, eliminating gate-refresh noise common in NMOS-based PWM dimming. When used, PWMTG enables flicker-free dimming with no audible noise - a key design value confirmed in LT8391EFE#TRPBF's typical application circuits for automotive lighting.
How is fault protection implemented in the LT8391EFE#TRPBF, and what options are available for fault response?
The LT8391EFE#TRPBF detects open LED (VFB > 0.95V & V(ISP-ISN) < 10mV) and short LED (VFB < 0.25V) conditions and reports them via the open-drain FAULT pin. Fault response mode - hiccup, latch-off, or keep-running - is configured by connecting a resistor from SS pin to VREF: 0Ω (hiccup), 499kΩ (latch-off), or 100kΩ (keep-running). This programmable behavior allows system-level fault handling flexibility in LT8391EFE#TRPBF deployments.
LT8391EFE#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
LT8391EFE#TRPBF FAQ
1.How can I place an order for LT8391EFE#TRPBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LT8391EFE#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 LT8391EFE#TRPBF reliable?
The price and inventory of LT8391EFE#TRPBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LT8391EFE#TRPBF is usually 5 days.
3.What payment methods are accepted for LT8391EFE#TRPBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LT8391EFE#TRPBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LT8391EFE#TRPBF?
LT8391EFE#TRPBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LT8391EFE#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 LT8391EFE#TRPBF?
For technical support, including LT8391EFE#TRPBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LT8391EFE#TRPBF requirements.
6.How does Aetrix verify that LT8391EFE#TRPBF is sourced from the original manufacturer or authorized distributors?
All LT8391EFE#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 LT8391EFE#TRPBF meets industry standards.
7.What is the process for return or replacement of LT8391EFE#TRPBF?
All LT8391EFE#TRPBF units undergo pre-shipment inspection (PSI). If there is an issue with LT8391EFE#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 LT8391EFE#TRPBF part is unused and in its original packaging.
Return procedure for LT8391EFE#TRPBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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