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Analog Devices Inc. LT8391AEFE#TRPBF
- Part No.:
- LT8391AEFE#TRPBF
- Manufacturer:
- Analog Devices Inc.
- Category:
- LED Drivers
- Package:
- 28-TSSOP (0.173", 4.40mm Width) Exposed Pad
- Datasheet:
-
LT8391AEFE#TRPBF.pdf
- Description:
- IC LED DRIVER CTRLR PWM 28TSSOP
- Quantity:
- Payment:
- Shipping:
Inventory:3,488
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Product details
Overview
LT8391AEFE#TRPBF 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 LT8391AEFE#TRPBF datasheet, LT8391AEFE#TRPBF pinout, LT8391AEFE#TRPBF application, or LT8391AEFE#TRPBF equivalent, key selection considerations include its 28-lead TSSOP package with exposed pad, AEC-Q100 qualification for automotive use, seamless region transitions, internal 5V INTVCC regulator, and dual analog dimming via CTRL1/CTRL2 with thermal derating capability.
Technical Context
The LT8391AEFE#TRPBF implements a single-inductor, 4-switch architecture with independent buck-side (SW1/TG1/BG1/BST1/LSP/LSN) and boost-side (SW2/TG2/BG2/BST2) gate drivers. Its proprietary current mode control uses one RSENSE for both buck and boost phases, enabling smooth VIN/VOUT crossover without discontinuity or audible noise.
It features dual regulation loops: a fast inner current loop (ISP/ISN → EA1 → VC) setting inductor peak current, and an outer voltage loop (FB → EA2 → VC clamp) providing overvoltage, open-LED, and short-LED protection. The SS pin enables soft-start timing and selectable fault response modes (hiccup/latch-off/keep-running) via resistor configuration.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| VIN Range | 4V to 60V - supports wide-input battery systems including 12V/24V/48V automotive and 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; synchronizable or spread-spectrum (25% triangle) for EMI reduction. |
| 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 high-end lighting control. |
| Operating Temp | –40°C to +125°C junction - qualified per AEC-Q100 Grade E for under-hood automotive applications. |
| Package | 28-lead TSSOP with exposed pad - provides low θJA = 30°C/W for thermally demanding LED driver PCBs. |
Pinout & Package
LT8391AEFE#TRPBF is housed in a 28-lead plastic TSSOP package (FE) with exposed thermal pad (Pin 29 = GND), optimized for high-power LED driver thermal management. Pin pitch is 0.65mm; body size is 9.7mm × 4.4mm.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| ISP / ISN | LED current sense differential inputs | Kelvin-connected to RLED; enable ±3% accurate current regulation and open/short LED fault detection. |
| CTRL1 / CTRL2 | Analog dimming and thermal derating inputs | Set LED current threshold (0–100mV) linearly; CTRL2 supports NTC-based thermal foldback without external IC. |
| PWM / RP | External/internal PWM dimming interface | PWM accepts 0–5V logic; RP sets internal dimming frequency (256–4096× switching freq) via resistor to GND. |
| PWMTG | High-side PMOS PWM switch driver | Inverted buffered PWM output referenced to VOUT; drives external PMOS for high-efficiency, low-noise LED current shutoff. |
| FAULT | Open-drain fault status output | Pulled low during open LED (VFB>0.95V & VISP-ISN<10mV) or short LED (VFB<0.25V); latched per SS-resistor mode. |
| SYNC/SPRD | Frequency control input | GND = internal oscillator; clock signal = synchronization; INTVCC = 25% triangle spread spectrum for EMI compliance. |
Key Features
| Feature | Design Value |
|---|---|
| Single-inductor 4-switch topology | Eliminates need for separate buck/boost controllers or coupled inductors; reduces BOM count and board area by >30% vs dual-stage solutions. |
| Seamless buck/buck-boost/boost transition | No current discontinuity or audible noise at VIN/VOUT crossovers (e.g., 12V input → 16V LED string); maintains regulation during engine cranking transients. |
| Integrated 5V INTVCC LDO | Supplies internal logic and gate drivers from VIN; 145mA current limit supports external bias for bootstrap capacitors and level-shifters. |
| Dual analog dimming with thermal compensation | CTRL1 sets baseline current; CTRL2 applies programmable thermal derating curve - avoids external thermistors and ADCs in lamp thermal management. |
| AEC-Q100 Grade E qualification | Validated for automotive ambient temperatures (–40°C to +125°C) and stress testing - suitable for front-end headlamp and DRL modules. |
Applications
| Automotive Headlamps | Industrial High-Bay Lighting |
|---|---|
Use Scenario: Adaptive driving beam (ADB) headlamps requiring precise, flicker-free dimming across 12V–48V vehicle electrical systems with cold-cranking immunity. IC Role / Device Role / Timing Role: Primary LED current controller managing up to 60V output with seamless VIN/VOUT crossover during start-stop cycles and load-dump events. Use Value: ±3% current accuracy ensures consistent photometric output; 2MHz operation minimizes inductor size for compact headlamp modules. | Use Scenario: High-efficiency 100W+ LED fixtures in warehouses and factories powered from 24V–48V DC microgrids or PoE++ infrastructure. IC Role / Device Role / Timing Role: Constant-current buck-boost controller enabling single-stage conversion from variable input to fixed LED string voltage, eliminating intermediate DC-DC stages. Use Value: 94% efficiency at 2MHz reduces thermal load on enclosed fixtures; spread-spectrum mode meets CISPR-11 Class B EMI limits without shielding. |
| Aviation Exterior Lighting | Emergency Vehicle Warning Lights |
Use Scenario: DO-160-compliant wingtip/navigation lights operating from 28V aircraft bus with wide transient tolerance (4V–56V). IC Role / Device Role / Timing Role: Fault-tolerant LED driver with open/short LED detection and latch-off FAULT reporting for avionics health monitoring. Use Value: AEC-Q100 qualification correlates with DO-160 environmental robustness; exposed-pad TSSOP aids conduction cooling in sealed housings. | Use Scenario: Flashing red/blue warning lamps in police/fire vehicles requiring ultra-fast PWM dimming (≤100ns edge rates) and thermal derating during extended operation. IC Role / Device Role / Timing Role: High-speed PWM controller with PWMTG output driving external PMOS for sub-microsecond LED turn-on/off control. Use Value: 2000:1 external PWM range enables precise flash intensity control; CTRL2 thermal foldback prevents LED thermal runaway during sustained strobe use. |
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#TRPBF | 4-switch buck-boost controller without integrated LED-specific features: no ISP/ISN sense, no FAULT pin, no PWM dimming support, no CTRL1/CTRL2 analog dimming. | Designed for general-purpose constant-voltage power supplies, not LED current regulation - requires external current sensing and fault logic. | Select only if building non-LED constant-voltage source; not drop-in for LED applications. |
| LM34927QMH/NOPB | 2-switch buck-boost controller (no buck-boost region); max VOUT = 42V; no spread spectrum; only 1000:1 PWM dimming; no AEC-Q100 rating. | Targeted at cost-sensitive industrial LED drivers where VIN never exceeds VOUT and automotive qualification is unnecessary. | Use when system VIN is always ≤ VOUT and thermal/EMI requirements are less stringent. |
Compared with LTC3789EFE#TRPBF and LM34927QMH/NOPB, the LT8391AEFE#TRPBF uniquely integrates LED-specific functions - ISP/ISN current sensing, FAULT reporting, 2000:1 PWM dimming, and AEC-Q100 qualification - making it the only direct solution for high-reliability, high-performance automotive and industrial LED lighting.
Availability
LT8391AEFE#TRPBF is available at Aetrix Electronics and suitable for automotive headlamps, industrial high-bay lighting, aviation exterior lighting, and emergency vehicle warning lights requiring stable component supply, long-term lifecycle support, and AEC-Q100-compliant sourcing.
Supply support for LT8391AEFE#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. (ADI) is a global leader in high-performance analog, mixed-signal, and digital signal processing semiconductors, founded in 1965 and headquartered in Wilmington, MA.
The LT8391A product line was designed specifically for high-efficiency, high-frequency, single-inductor 4-switch buck-boost LED driving in automotive and industrial environments - emphasizing seamless region transitions, integrated fault protection, and precision analog dimming.
FAQ
What is the maximum LED string voltage supported by the LT8391AEFE#TRPBF?
The LT8391AEFE#TRPBF supports a VOUT range of 0V to 60V, with practical LED string operation up to 51V forward voltage as specified in the datasheet. This allows driving configurations such as 16× white LEDs (3.2V each) or mixed-color strings while maintaining regulation across all buck, buck-boost, and boost regions. The 60V absolute maximum rating provides margin for transients.
Does the LT8391AEFE#TRPBF require external current sense resistors?
Yes, the LT8391AEFE#TRPBF requires two external Kelvin-connected sense resistors: one (RSENSE) between LSP and LSN for inductor current sensing in buck/boost modes, and another (RLED) between ISP and ISN for LED current regulation. Both are mandatory for proper operation, fault detection, and ±3% current accuracy - no internal sense elements are provided.
How does the LT8391AEFE#TRPBF handle input voltage transients common in automotive systems?
The LT8391AEFE#TRPBF is rated for 4V to 60V continuous input and withstands 4V to 56V transients, covering ISO 7637-2 Pulse 4 (cold crank) and Pulse 5a/b (load dump). Its proprietary peak-buck/peak-boost control maintains regulation during rapid VIN changes, while the EN/UVLO pin's 1.220V falling threshold and 2.5µA pull-down enable precise, hysteresis-controlled startup sequencing under unstable battery conditions.
Can the LT8391AEFE#TRPBF be synchronized to an external clock?
Yes, the LT8391AEFE#TRPBF supports external synchronization via the SYNC/SPRD pin. When driven with a TTL- or CMOS-compatible clock signal (600kHz–2100kHz), the internal oscillator locks to the external frequency - enabling deterministic EMI reduction, multi-phase interleaving, or noise avoidance in sensitive RF systems. No additional components are required beyond the clock source.
What fault protection mechanisms are built into the LT8391AEFE#TRPBF?
The LT8391AEFE#TRPBF provides comprehensive LED fault protection: open LED detection (VFB > 0.95V & VISP-ISN < 10mV), short LED detection (VFB < 0.25V), and overvoltage shutdown (VFB > 1.05V). Fault status is reported on the open-drain FAULT pin and can be configured for hiccup, latch-off, or keep-running behavior using a resistor on the SS pin.
LT8391AEFE#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:
- 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
LT8391AEFE#TRPBF FAQ
1.How can I place an order for LT8391AEFE#TRPBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LT8391AEFE#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 LT8391AEFE#TRPBF reliable?
The price and inventory of LT8391AEFE#TRPBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LT8391AEFE#TRPBF is usually 5 days.
3.What payment methods are accepted for LT8391AEFE#TRPBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LT8391AEFE#TRPBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LT8391AEFE#TRPBF?
LT8391AEFE#TRPBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LT8391AEFE#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 LT8391AEFE#TRPBF?
For technical support, including LT8391AEFE#TRPBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LT8391AEFE#TRPBF requirements.
6.How does Aetrix verify that LT8391AEFE#TRPBF is sourced from the original manufacturer or authorized distributors?
All LT8391AEFE#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 LT8391AEFE#TRPBF meets industry standards.
7.What is the process for return or replacement of LT8391AEFE#TRPBF?
All LT8391AEFE#TRPBF units undergo pre-shipment inspection (PSI). If there is an issue with LT8391AEFE#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 LT8391AEFE#TRPBF part is unused and in its original packaging.
Return procedure for LT8391AEFE#TRPBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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