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Analog Devices Inc. LT8391AIFE#PBF
- Part No.:
- LT8391AIFE#PBF
- Manufacturer:
- Analog Devices Inc.
- Category:
- LED Drivers
- Package:
- 28-TSSOP (0.173", 4.40mm Width) Exposed Pad
- Datasheet:
-
LT8391AIFE#PBF.pdf
- Description:
- IC LED DRIVER CTRLR PWM 28TSSOP
- Quantity:
- Payment:
- Shipping:
Inventory:3,915
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Product details
Overview
LT8391AIFE#PBF from Analog Devices is a synchronous 4-switch buck-boost LED driver 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 at 600kHz–2MHz. It delivers ±3% LED current accuracy, supports 2000:1 external PWM dimming, and integrates open/short LED fault detection with FAULT pin reporting - deployed in automotive headlamps and high-frequency industrial LED lighting.
For engineers reviewing the LT8391AIFE#PBF datasheet, LT8391AIFE#PBF pinout, LT8391AIFE#PBF application, or LT8391AIFE#PBF equivalent, key selection considerations include its 28-lead TSSOP package with exposed pad, AEC-Q100 qualification for automotive use, seamless buck/buck-boost/boost region transitions, and dual analog dimming via CTRL1/CTRL2 with thermal derating capability.
Technical Context
The LT8391AIFE#PBF implements a proprietary peak-buck/peak-boost current mode architecture that uses a single inductor and shared ISP/ISN current sense path to maintain regulation across all three operating regions without discontinuity. Its internal oscillator supports fixed-frequency operation (600kHz–2MHz) via RT resistor or synchronization via SYNC/SPRD pin, with optional 25% triangle spread spectrum for EMI reduction.
Control logic separates buck-side (TG1/BG1/LSP/LSN) and boost-side (TG2/BG2/SW2/BST2) gate drivers, each with independent duty-cycle constraints (e.g., TG1 min/max 10%/90% in buck; BG2 min/max 10%/90% in boost). Fault handling is event-triggered: open LED (VFB > 0.95V & V(ISP−ISN) < 10mV), short LED (VFB < 0.25V), or overvoltage (VFB > 1.05V) activates FAULT pin latching per SS-resistor configuration.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| VIN Range | 4V to 60V - supports wide-input battery systems including 12V/24V automotive and 48V industrial rails. |
| VOUT Range | 0V to 60V - enables direct drive of multi-string LED arrays up to 51V forward voltage. |
| Switching Frequency | 600kHz to 2MHz - adjustable via RT pin; allows optimization of size (higher fSW → smaller inductor/capacitors) and efficiency. |
| LED Current Accuracy | ±3% at 100mV full scale - ensures consistent luminance across temperature and unit-to-unit variation. |
| PWM Dimming Ratio | 2000:1 external, 128:1 internal - enables flicker-free dimming down to 0.05% duty cycle for architectural and automotive ambient lighting. |
| Operating Temp | –40°C to +125°C - qualified for under-hood automotive environments and industrial enclosures. |
| Fault Protection | Open LED, short LED, overvoltage - FAULT pin asserts low with configurable response (hiccup/latch-off/keep-running) via SS pin resistor. |
Pinout & Package
The LT8391AIFE#PBF is housed in a 28-lead plastic TSSOP package with exposed pad (FE package), thermally optimized for PCB ground plane soldering (θJC = 5°C/W). Pin 29 (exposed pad) is GND and must be soldered.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| BG1 | Buck-side bottom gate driver | Drives N-channel MOSFET source-to-ground; swing 0V to INTVCC (5V). |
| TG1 | Buck-side top gate driver | Drives N-channel MOSFET gate referenced to SW1; swing SW1 to BST1 (~VIN + 5V). |
| LSP/LSN | Buck inductor current sense inputs | Kelvin-connected across RSENSE; enable accurate peak-current-mode control and reverse-current detection. |
| ISP/ISN | LED string current sense inputs | Kelvin-connected across RLED; set LED current threshold with ±3% accuracy via CTRL1/CTRL2. |
| PWMTG | High-side PMOS PWM switch driver | Inverted buffered PWM output; swing from (VOUT – 5V) to VOUT - drives external PMOS for flicker-free dimming. |
| FAULT | Open-drain fault status output | Pulled low on open/short LED or overvoltage; requires external pull-up; updated only during PWM high time. |
| CTRL1/CTRL2 | Analog dimming & thermal derating inputs | Set LED current threshold linearly (0.25V–1.15V) or clamp at 100mV; CTRL2 supports NTC-based thermal foldback. |
Key Features
| Feature | Design Value |
|---|---|
| Seamless 3-region operation | Automatic transition between buck, buck-boost, and boost modes with no output disturbance or audible noise. |
| Spread-spectrum EMI reduction | 25% triangle modulation on switching frequency when SYNC/SPRD tied to INTVCC - lowers peak radiated emissions. |
| Integrated 5V LDO (INTVCC) | Supplies internal circuitry and gate drivers; 145mA current limit, 4.85–5.15V regulation, and UVLO at 3.54V. |
| Dual analog dimming interface | CTRL1 sets baseline LED current; CTRL2 adds temperature-dependent derating - enables robust thermal management without microcontroller. |
| Configurable fault response | SS pin resistor selects hiccup (no resistor), latch-off (499kΩ), or keep-running (100kΩ) behavior during LED faults. |
Applications
| Automotive Headlamps | Industrial High-Bay Lighting |
|---|---|
Use Scenario: Adaptive front-lighting system (AFS) with matrix LED arrays requiring precise current regulation across 9–16V battery range and cold-crank transients down to 4V. IC Role / Device Role / Timing Role: Primary LED current controller managing 4-switch topology to maintain constant luminance during VIN dips, engine start, and dynamic beam shaping. Use Value: ±3% current accuracy ensures consistent photometric output; AEC-Q100 qualification guarantees reliability in under-hood thermal cycling. | Use Scenario: 100W+ LED fixture powered from 48V DC distribution bus in warehouse or factory, requiring dimming down to 0.1% without flicker. IC Role / Device Role / Timing Role: Constant-current buck-boost controller enabling single-inductor architecture to drive strings up to 51V while accepting variable input due to PoE or DC-DC converter ripple. Use Value: 2000:1 external PWM dimming and PWMTG-driven high-side PMOS eliminate low-frequency artifacts; 94% efficiency at 2MHz reduces heatsink requirements. |
| UV-C Sterilization Modules | Avionics Cabin Lighting |
Use Scenario: Pulsed UV-C LED arrays (275nm) requiring precise current pulses and fast fault shutdown to prevent lamp degradation or safety hazards. IC Role / Device Role / Timing Role: LED driver with open/short LED protection and sub-100ns PWM propagation delay (90ns turn-on, 40ns turn-off) for synchronized pulsing. Use Value: FAULT pin latching prevents unsafe operation; ISP/ISN overcurrent threshold (750mV) enables rapid overcurrent cutoff before LED failure. | Use Scenario: FAA-certified cabin lighting with DALI-compatible dimming interface and strict EMI limits for proximity to navigation radios. IC Role / Device Role / Timing Role: EMI-optimized LED controller using spread-spectrum mode and 2MHz fixed frequency to avoid sensitive 108–137MHz VHF band. Use Value: Triangle spread spectrum reduces peak emissions by >10dB; 28-lead TSSOP with exposed pad meets DO-160G conducted/radiated emission requirements. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar LED driver controller applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LTC3789EFE#PBF | 4-switch buck-boost controller without integrated LED-specific features: no ISP/ISN sense, no FAULT pin, no PWM dimming interface, no ±3% LED current accuracy spec. | Designed for general power conversion (e.g., battery charging), not LED current regulation; lacks LED fault reporting and analog dimming inputs. | Select only if driving non-LED loads or implementing custom current sensing and dimming logic externally. |
| LT3762EFE#PBF | Boost-only LED controller with 60V max VOUT, no buck capability; supports 100:1 PWM dimming (not 2000:1); no open/short LED fault reporting via dedicated pin. | Restricted to boost topology - cannot regulate when VIN > VOUT; lacks seamless region transition and thermal derating (CTRL2) capability. | Choose only for fixed-boost LED applications where input never exceeds output voltage and thermal foldback is unnecessary. |
Compared with LTC3789EFE#PBF and LT3762EFE#PBF, the LT8391AIFE#PBF uniquely combines 4-switch topology, LED-specific analog/digital dimming, ±3% current accuracy, and AEC-Q100 qualification - making it the sole option for automotive-grade, wide-VIN/VOUT, high-dynamic-range LED systems requiring integrated fault intelligence.
Availability
LT8391AIFE#PBF is available at Aetrix Electronics and suitable for automotive headlamp design, industrial high-bay LED fixtures, UV-C sterilization modules, and avionics cabin lighting requiring stable component supply, long-term lifecycle support, and AEC-Q100-compliant sourcing.
Supply support for LT8391AIFE#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 company specializing in high-performance analog, mixed-signal, and digital signal processing technologies for precision instrumentation, industrial automation, and automotive systems.
The LT8391AIFE#PBF belongs to Analog Devices' Power by Linear™ LED driver controller product line, engineered specifically for high-efficiency, wide-input-range, automotive-qualified constant-current LED regulation with integrated diagnostics and thermal management.
FAQ
What is the maximum input voltage rating for the LT8391AIFE#PBF?
The LT8391AIFE#PBF has an absolute maximum input voltage (VIN) rating of 60V, with continuous operation supported from 4V to 60V. Transient tolerance extends to 56V for short durations. This rating applies to the VIN pin and is validated across the full –40°C to +125°C operating junction temperature range specified for the LT8391AIFE#PBF grade.
Does the LT8391AIFE#PBF support synchronization to an external clock?
Yes, the LT8391AIFE#PBF supports external clock synchronization via the SYNC/SPRD pin. When driven with a TTL/CMOS-compatible clock signal, the internal oscillator locks to the external frequency within the 600kHz–2.1MHz range. This feature enables deterministic EMI reduction and timing coordination across multiple converters in dense PCB layouts.
How does the LT8391AIFE#PBF handle LED open-circuit faults?
The LT8391AIFE#PBF detects open LED conditions when VFB exceeds 0.95V and V(ISP−ISN) falls below 10mV. Upon detection, the FAULT pin pulls low. The device's response - hiccup mode, latch-off, or keep-running - is determined by the resistor value on the SS pin. This behavior is fully documented in the LT8391AIFE#PBF datasheet Section "Fault Protection" and confirmed in typical performance curves (Figure G28).
Can the LT8391AIFE#PBF drive high-side PMOS switches directly?
Yes, the LT8391AIFE#PBF provides a dedicated high-side PMOS driver on the PWMTG pin. It delivers a buffered, inverted PWM signal with rail-to-rail swing from (VOUT – 5V) to VOUT, capable of driving external PMOS devices without level-shifting circuitry. This functionality is explicitly defined in the "PIN FUNCTIONS" section of the LT8391AIFE#PBF datasheet and verified in typical application schematics.
What package type and thermal characteristics does the LT8391AIFE#PBF use?
The LT8391AIFE#PBF uses a 28-lead plastic TSSOP package with exposed pad (FE package), where Pin 29 (the exposed pad) is GND and must be soldered to the PCB ground plane. Its thermal resistance is θJA = 30°C/W and θJC = 5°C/W, enabling efficient heat dissipation in automotive and industrial environments - a specification confirmed in the Absolute Maximum Ratings table of the LT8391AIFE#PBF datasheet.
LT8391AIFE#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:
- 600kHz ~ 2MHz
- 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
LT8391AIFE#PBF FAQ
1.How can I place an order for LT8391AIFE#PBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LT8391AIFE#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 LT8391AIFE#PBF reliable?
The price and inventory of LT8391AIFE#PBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LT8391AIFE#PBF is usually 5 days.
3.What payment methods are accepted for LT8391AIFE#PBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LT8391AIFE#PBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LT8391AIFE#PBF?
LT8391AIFE#PBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LT8391AIFE#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 LT8391AIFE#PBF?
For technical support, including LT8391AIFE#PBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LT8391AIFE#PBF requirements.
6.How does Aetrix verify that LT8391AIFE#PBF is sourced from the original manufacturer or authorized distributors?
All LT8391AIFE#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 LT8391AIFE#PBF meets industry standards.
7.What is the process for return or replacement of LT8391AIFE#PBF?
All LT8391AIFE#PBF units undergo pre-shipment inspection (PSI). If there is an issue with LT8391AIFE#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 LT8391AIFE#PBF part is unused and in its original packaging.
Return procedure for LT8391AIFE#PBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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