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Analog Devices Inc. LT8391EFE#PBF
- Part No.:
- LT8391EFE#PBF
- Manufacturer:
- Analog Devices Inc.
- Category:
- LED Drivers
- Package:
- 28-TSSOP (0.173", 4.40mm Width) Exposed Pad
- Datasheet:
-
LT8391EFE#PBF.pdf
- Description:
- IC LED DRIVER CTRLR PWM 28TSSOP
- Quantity:
- Payment:
- Shipping:
Inventory:178
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Product details
Overview
LT8391EFE#PBF 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 voltage (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 LT8391EFE#PBF datasheet, LT8391EFE#PBF pinout, LT8391EFE#PBF application, or LT8391EFE#PBF equivalent, key selection considerations include its seamless buck/buck-boost/boost region transitions, internal/external PWM dimming (128:1 / 2000:1), open/short LED fault reporting via FAULT pin, and AEC-Q100 qualification for automotive use.
Technical Context
The LT8391EFE#PBF implements a dual-mode current-sense architecture with shared LSP/LSN pins for inductor current sensing and ISP/ISN pins for LED current sensing, enabling precise regulation independent of VIN/VOUT ratio. Its proprietary peak-buck/peak-boost 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 features two independent gate driver stages: TG1/BG1 for buck-side N-MOSFETs (with BST1 bootstrap supply) and TG2/BG2 for boost-side N-MOSFETs (with BST2 bootstrap supply), each with verified 2.6Ω pull-up / 1.4Ω pull-down on-resistance and <25ns rise/fall times. The integrated 5V INTVCC LDO powers all internal circuitry and drivers.
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 direct drive of multi-string high-voltage LED arrays without external level-shifting. |
| LED Current Accuracy | ±3% at 100mV full scale - ensures consistent luminance across temperature and unit-to-unit variation in production. |
| Switching Frequency | 150kHz to 650kHz (adjustable via RT pin) - allows EMI optimization and inductor size reduction while maintaining >98% efficiency at 25V/2A. |
| PWM Dimming Ratio | 2000:1 external, 128:1 internal - provides flicker-free dimming down to 0.05% duty cycle for premium lighting control. |
| 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. |
| Operating Temp | –40°C to +125°C junction - validated for under-hood automotive headlamp applications per AEC-Q100 Grade E. |
Pinout & Package
LT8391EFE#PBF is housed in a 28-lead plastic TSSOP package with exposed pad (pin 29 = GND), θJA = 30°C/W, requiring soldering of the exposed pad to PCB ground plane for thermal and electrical integrity.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| EN/UVLO | Enable & undervoltage lockout input | Shuts down IC when <0.3V; enables at >1.214V falling threshold; 2.5µA internal pull-down enables precise VIN UVLO programming. |
| ISP/ISN | High-side LED current sense differential inputs | Measure LED string current with Kelvin connection; full-scale threshold programmable from 0–100mV via CTRL1/CTRL2. |
| LSP/LSN | Buck-side inductor current sense differential inputs | Provide single-point current feedback for peak-buck/peak-boost mode transition and reverse-current detection. |
| TG1/BG1/TG2/BG2 | N-MOSFET gate drivers | Drive external high-side/low-side switches; TG1/BG1 for buck path, TG2/BG2 for boost path; integrated bootstrap diodes on BST1/BST2. |
| PWMTG | Inverted PWM top-gate driver | Drives external high-side PMOS switch with rail-to-rail swing referenced to VOUT; enables true high-side PWM dimming without floating drivers. |
| FAULT | Open-drain fault status output | Pulled low during open/short LED faults; updated only during PWM high state and latched during PWM low state. |
Key Features
| Feature | Design Value |
|---|---|
| 4-switch single-inductor topology | Eliminates need for separate buck and boost converters-reduces BOM count, board area, and design complexity for wide-VIN LED drivers. |
| Seamless region transition | No audible noise or current glitch during VIN/VOUT crossover (e.g., 12V→24V input change); transition thresholds tightly specified (±2% tolerance). |
| Integrated bootstrap diodes | Removes two external Schottky diodes per channel-simplifies layout, improves reliability, and reduces component cost. |
| Flicker-free spread spectrum | ±15% triangle modulation around oscillator frequency (via SYNC/SPRD tied to INTVCC)-lowers peak EMI by >10dB without compromising regulation. |
| AEC-Q100 qualified | Validated for automotive Grade E (–40°C to +125°C) with full reliability testing-enables direct use in headlamp, DRL, and fog lamp modules. |
Applications
| Automotive Head Lamps | Industrial High-Bay Lighting |
|---|---|
Use Scenario: Adaptive front-lighting system (AFS) with dynamic beam shaping and matrix LED control in passenger vehicles. IC Role / Device Role / Timing Role: Primary LED current controller managing up to 50W per channel with synchronized PWM dimming across multiple zones. Use Value: ±3% LED current accuracy ensures consistent photometric output across temperature; AEC-Q100 qualification eliminates requalification effort. |
Use Scenario: 100–200W LED fixtures for warehouse and factory floor illumination powered from 24V or 48V DC microgrids. IC Role / Device Role / Timing Role: Constant-current buck-boost regulator enabling single-driver solution for varying LED string configurations (e.g., 12–36V forward voltage). Use Value: 4V–60V input range accommodates brownout and overvoltage conditions; 98% efficiency minimizes thermal load in enclosed fixtures. |
| Emergency Vehicle Warning Lights | UV-C Sterilization Modules |
Use Scenario: Flashing red/blue LED arrays in police, fire, and ambulance light bars requiring high peak brightness and rapid on/off transitions. IC Role / Device Role / Timing Role: High-speed PWM dimming controller with 2000:1 external dimming ratio and <130ns PWM-to-PWMTG propagation delay. Use Value: Sub-microsecond timing precision enables crisp flash edges; open/short LED fault reporting prevents single-LED failure from disabling entire array. |
Use Scenario: Pulsed UV-C LED drivers for surface disinfection systems requiring precise dose control via current and time modulation. IC Role / Device Role / Timing Role: Precision current source with analog dimming (20:1) and thermal derating (via CTRL2) to protect GaN-based UV LEDs from thermal runaway. Use Value: 0.25V–2V CTRL1/CTRL2 interface enables linear current scaling; ±3% accuracy ensures repeatable UV dose delivery per pulse. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar LED controller applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LT3965EFE#PBF | 4-switch buck-boost LED controller with I²C interface, 12-bit DAC dimming, and built-in fault diagnostics; requires external MCU for configuration. | Targeted at smart lighting systems needing digital control and telemetry-not suitable for standalone analog-dimming designs. | Select when system-level intelligence (e.g., DALI, DMX) is required; avoid if minimal BOM and analog simplicity are priorities. |
| LM3423MH/NOPB | Asynchronous boost-only LED controller; no buck or buck-boost capability; max 55V output; no integrated bootstrap diodes. | Limited to boost-only topologies; cannot regulate when VIN > VOUT-requires redesign for automotive start-stop or battery discharge scenarios. | Acceptable only for fixed-VIN > VOUT applications (e.g., 12V → 36V LED strings); not drop-in compatible due to topology and pinout differences. |
Compared with LT3965EFE#PBF and LM3423MH/NOPB, the LT8391EFE#PBF uniquely combines analog-dimming simplicity, seamless wide-VIN/VOUT operation, and AEC-Q100 qualification-making it the only choice for cost-sensitive, high-reliability automotive LED drivers without digital infrastructure.
Availability
LT8391EFE#PBF is available at Aetrix Electronics and suitable for automotive headlamps, industrial high-bay lighting, emergency vehicle warning lights, and UV-C sterilization modules requiring stable component supply, long-term lifecycle support, and AEC-Q100-compliant sourcing.
Supply support for LT8391EFE#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 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-efficiency, wide-input-range LED current regulation in harsh environments-emphasizing seamless topology transitions, robust fault handling, and automotive-grade reliability.
FAQ
What is the maximum LED output voltage supported by the LT8391EFE#PBF?
The LT8391EFE#PBF supports a VOUT range of 0V to 60V, with absolute maximum ratings specifying 60V on the VOUT pin. In practice, the device reliably regulates LED strings up to 51V forward voltage, as confirmed in the Typical Application section and Absolute Maximum Ratings table. This makes LT8391EFE#PBF suitable for multi-series white LED arrays and high-voltage UV-C LED modules.
Does the LT8391EFE#PBF require external bootstrap diodes?
No, the LT8391EFE#PBF integrates Schottky bootstrap diodes from INTVCC to BST1 and BST2 pins, eliminating the need for two external diodes per channel. This is explicitly stated in the PIN FUNCTIONS section and reduces component count, PCB area, and potential failure points. External bootstrap capacitors (e.g., 0.1µF ceramic) are still required between BST1–SW1 and BST2–SW2.
How does the LT8391EFE#PBF handle LED open-circuit faults?
The LT8391EFE#PBF detects open LED conditions when VFB exceeds 0.95V *and* V(ISP−ISN) falls below 10mV. Upon detection, it asserts the open-drain FAULT pin low and enters a user-configurable response mode (hiccup, latch-off, or keep-running) determined by the resistor value on the SS pin. This behavior is fully documented in the Electrical Characteristics and Applications Information sections of the LT8391EFE#PBF datasheet.
Can the LT8391EFE#PBF operate in buck-only mode with VIN > VOUT?
Yes, the LT8391EFE#PBF operates seamlessly in buck mode when VIN/VOUT > 1.18, transitioning automatically to buck-boost or boost as the ratio changes. Its proprietary peak-buck current mode control maintains stable regulation and low-noise operation throughout-verified in the TYPICAL PERFORMANCE CHARACTERISTICS plots (e.g., Figure G04–G06) and Region Transition specifications (e.g., Buck to Buck-Boost at VIN/VOUT = 1.18).
What is the purpose of the PWMTG pin on the LT8391EFE#PBF?
The PWMTG pin on the LT8391EFE#PBF provides an inverted, buffered version of the PWM input signal, driving an external high-side PMOS switch with rail-to-rail swing referenced to VOUT (from VOUT–5V to VOUT). This enables true high-side PWM dimming without requiring isolated gate drivers or level shifters-critical for minimizing EMI and achieving clean, flicker-free dimming in sensitive lighting applications.
LT8391EFE#PBF Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- -
- Package/Case:
- 28-TSSOP (0.173", 4.40mm Width) 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 ~ 125°C (TJ)
- Grade:
- Automotive
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 28-TSSOP-EP
LT8391EFE#PBF FAQ
1.How can I place an order for LT8391EFE#PBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LT8391EFE#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 LT8391EFE#PBF reliable?
The price and inventory of LT8391EFE#PBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LT8391EFE#PBF is usually 5 days.
3.What payment methods are accepted for LT8391EFE#PBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LT8391EFE#PBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LT8391EFE#PBF?
LT8391EFE#PBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LT8391EFE#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 LT8391EFE#PBF?
For technical support, including LT8391EFE#PBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LT8391EFE#PBF requirements.
6.How does Aetrix verify that LT8391EFE#PBF is sourced from the original manufacturer or authorized distributors?
All LT8391EFE#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 LT8391EFE#PBF meets industry standards.
7.What is the process for return or replacement of LT8391EFE#PBF?
All LT8391EFE#PBF units undergo pre-shipment inspection (PSI). If there is an issue with LT8391EFE#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 LT8391EFE#PBF part is unused and in its original packaging.
Return procedure for LT8391EFE#PBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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