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Analog Devices Inc. LT8391DJUFDM#WPBF
- Part No.:
- LT8391DJUFDM#WPBF
- Manufacturer:
- Analog Devices Inc.
- Category:
- LED Drivers
- Package:
- 28-WFQFN Exposed Pad
- Datasheet:
-
LT8391DJUFDM#WPBF.pdf
- Description:
- 60VSYNC 4-SWITCH BUCK-BOOST LED
- Quantity:
- Payment:
- Shipping:
Inventory:3,507
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Product details
Overview
LT8391DJUFDM#WPBF from Analog Devices is a synchronous 4-switch buck-boost LED controller IC that regulates constant LED current across input voltages (4V–60V) both above, below, or equal to output (0V–60V), enabling seamless mode transitions in automotive headlamps and industrial lighting. It delivers ±4% LED current accuracy at 100mV full scale, supports 150kHz–650kHz adjustable switching frequency, and integrates open/short LED fault detection with FAULT pin reporting.
For engineers reviewing the LT8391DJUFDM#WPBF datasheet, LT8391DJUFDM#WPBF pinout, LT8391DJUFDM#WPBF application, or LT8391DJUFDM#WPBF equivalent, key selection criteria include its AEC-Q100 qualification, 98% peak efficiency at 25V/2A, spread-spectrum EMI reduction, and dual gate drivers (TG1/BG1/TG2/BG2) supporting external NMOS switches in single-inductor architecture.
Technical Context
The LT8391DJUFDM#WPBF implements Analog Devices' proprietary peak-buck/peak-boost current-mode control using a single inductor current sense resistor (LSP/LSN) and dual comparators (A3/A4) to manage four power switches across buck, buck-boost, and boost regions. Its operation dynamically selects between buck logic and boost logic based on VIN/VOUT ratio, with hysteresis preventing chattering during region transitions.
It features two independent bootstrap supplies (BST1/BST2), internal 5V INTVCC LDO (4.85–5.15V), 2V VREF reference, and VC error amplifier output driving both current sense thresholds. Fault protection includes FB overvoltage (1.05V), open LED (0.95V), and short LED (0.05V) detection, with latch-off, hiccup, or keep-running modes configurable via SS pin resistor.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| VIN Range | 4V to 60V - supports 12V/24V/48V automotive and battery systems without external pre-regulation. |
| VOUT Range | 0V to 60V - enables direct drive of multi-LED strings up to 17+ white LEDs (≈51V) or low-voltage COB modules. |
| Switching Frequency | 150kHz to 650kHz - adjustable via RT pin resistor; ±15% triangle spread spectrum reduces EMI peaks for automotive EMC compliance. |
| LED Current Accuracy | ±4% at 100mV full scale - ensures consistent luminance across temperature (-40°C to 150°C) and line/load variations. |
| Efficiency | 98% at 25V/2A - achieved via synchronous 4-switch topology eliminating diode losses and minimizing conduction loss in high-current paths. |
| Fault Protection | Open LED (FB > 0.95V), short LED (FB < 0.05V), overvoltage (FB > 1.05V) - FAULT pin asserts open-drain low with user-selectable response mode. |
| Operating Temp | -40°C to 150°C junction - qualified per AEC-Q100 Grade 1, suitable for under-hood automotive LED driver placement. |
Pinout & Package
LT8391DJUFDM#WPBF is housed in a 28-lead (4mm × 5mm) plastic side-wettable QFN (UFDM) package with exposed thermal pad (Pin 29 = GND). The package supports automated optical inspection (AOI) and provides θJA = 34°C/W for high-power LED driver thermal management.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| TG1, TG2 | Buck/Boost top gate drives | Drive external high-side NMOS (SW1/SW2 nodes); each swings from SWx to BSTx, enabling bootstrap operation. |
| BG1, BG2 | Buck/Boost bottom gate drives | Drive external low-side NMOS; swing from GND to INTVCC (5V), compatible with standard logic-level MOSFETs. |
| LSP/LSN | Buck-side inductor current sense | Kelvin connection to RSENSE for accurate peak-buck current sensing and reverse-current detection in all modes. |
| ISP/ISN | LED string current sense | Kelvin connection to RLED; sets LED current threshold via CTRL pin (0–100mV range) with ±4% accuracy. |
| FB | Voltage loop feedback | Regulates to 1.00V for CV operation; triggers FAULT on open (FB > 0.95V) or short (FB < 0.05V) conditions. |
| CTRL | LED current programming | Analog dimming input: ILED = Min(VCTRL − 0.25V, 1V) / (10 × RLED); enables 20:1 analog dimming range. |
| FAULT | Open-drain fault indicator | Pulled low during LED fault; updated only during PWM high state and latched during PWM low for stable reporting. |
| SS | Soft-start/fault mode control | Capacitor sets soft-start ramp time; resistor to VREF configures fault response: hiccup (no resistor), latch-off (499k), keep-running (100k). |
Key Features
| Feature | Design Value |
|---|---|
| Single-inductor 4-switch architecture | Eliminates need for separate buck + boost stages; reduces BOM count, PCB area, and magnetic component cost vs dual-converter solutions. |
| Seamless buck/buck-boost/boost transition | No audible noise or light flicker during VIN/VOUT crossing; maintains continuous LED current regulation without interruption. |
| Integrated 5V INTVCC LDO | Supplies internal circuitry and gate drivers; eliminates need for external bias rail; 80–160mA current limit supports driving multiple external MOSFETs. |
| AEC-Q100 Grade 1 qualification | Validated for automotive applications including headlamps and DRLs; supports -40°C to +150°C junction operation with production reliability data. |
| Spread-spectrum EMI reduction | ±15% triangle modulation lowers peak radiated emissions by >10dB, easing CISPR 25 Class 5 compliance in vehicle ECU designs. |
Applications
| Automotive Head Lamps | Industrial High-Bay Lighting |
|---|---|
Use Scenario: Adaptive front-lighting system (AFS) requiring dynamic beam shaping across varying battery voltage (9–16V) and LED string configurations (3–12 LEDs). IC Role / Device Role / Timing Role: Primary LED current controller managing 4-switch power stage; regulates constant current while transitioning seamlessly between buck (engine running) and boost (cold crank) modes. Use Value: Maintains ±4% luminance stability across 12V–60V input transients and temperature extremes, meeting SAE J1127 and ISO 16750-2 requirements. | Use Scenario: 100W+ high-bay fixture powered from 24VDC industrial bus, driving 30–50V LED strings with programmable dimming. IC Role / Device Role / Timing Role: Constant-current LED driver IC with analog + PWM dimming interface; uses CTRL and PWM pins for DALI-compatible dimming control. Use Value: 98% efficiency minimizes thermal load in enclosed fixtures; spread-spectrum operation meets EN 55015 conducted/radiated EMI limits. |
| Battery-Powered Emergency Lighting | UV-C Disinfection Modules |
Use Scenario: Portable emergency egress light using Li-ion (3.0–4.2V/cell) or lead-acid (10–14V) battery, driving 24–48V LED arrays. IC Role / Device Role / Timing Role: Wide-input buck-boost LED controller enabling single-stage conversion from low battery to high-Vf UV-A/white LEDs. Use Value: 4V minimum VIN allows operation down to near-dead battery; integrated fault reporting enables self-test and status indication via FAULT pin. | Use Scenario: Pulsed UV-C disinfection system using 365nm LEDs requiring precise current control and fast on/off switching. IC Role / Device Role / Timing Role: High-accuracy current regulator with sub-µs PWM response; FAULT pin monitors open-circuit failure of fragile UV-C diodes. Use Value: ±4% current accuracy ensures consistent germicidal dose delivery; 150kHz–650kHz frequency tuning avoids resonance in compact metal housings. |
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 integrated 50V MOSFETs; fixed 500kHz frequency; no spread spectrum; lower max VIN (55V). | Targeted at space-constrained designs where integration reduces layout complexity; lacks AEC-Q100 qualification. | Choose LT3965EFE#PBF when board area is critical and external MOSFETs are undesirable; avoid for automotive under-hood use. |
| LM3423MH/NOPB | Controller-only (no integrated LDO); requires external 5V bias; max VIN 75V; no spread spectrum; no AEC-Q100 rating. | Suitable for high-input industrial LED drivers where cost sensitivity outweighs EMI performance; limited thermal rating (–40°C to 125°C). | Choose LM3423MH/NOPB for non-automotive 72VDC systems needing higher input voltage margin; verify external bias design robustness. |
Compared with LT3965EFE#PBF and LM3423MH/NOPB, the LT8391DJUFDM#WPBF uniquely combines AEC-Q100 qualification, ±15% spread spectrum, and seamless mode transition-making it the only option qualified for automotive headlamp duty cycles with stringent EMI and reliability requirements.
Availability
LT8391DJUFDM#WPBF is available at Aetrix Electronics and suitable for automotive headlamps, industrial high-bay lighting, and battery-powered emergency lighting requiring stable component supply, long-term lifecycle support, and AEC-Q100-compliant sourcing.
Supply support for LT8391DJUFDM#WPBF 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 precision instrumentation, industrial automation, and automotive safety markets.
The LT8391D product line delivers high-efficiency, wide-input-range LED controllers optimized for automotive lighting systems demanding AEC-Q100 reliability, low EMI, and seamless buck-boost operation without microcontroller intervention.
FAQ
What is the maximum LED string voltage supported by the LT8391DJUFDM#WPBF?
The LT8391DJUFDM#WPBF supports output voltages up to 60V, enabling direct drive of LED strings with forward voltages up to ≈51V (e.g., 17× white LEDs at 3V each) or UV-C arrays requiring 36–40V. Its 0V–60V VOUT range allows operation even with zero-output configurations when used in current-source mode with external sensing.
How does the LT8391DJUFDM#WPBF achieve seamless buck-to-boost transition without flicker?
The LT8391DJUFDM#WPBF uses proprietary peak-buck/peak-boost current-mode control with hysteresis-based region detection and dual comparators (A3/A4). It continuously monitors VIN/VOUT ratio and adjusts switch timing-maintaining continuous inductor current and constant LED current regulation across all three regions (buck, buck-boost, boost) without interruption or visible light modulation.
Can the LT8391DJUFDM#WPBF be used without an external microcontroller for analog dimming?
Yes. The LT8391DJUFDM#WPBF supports standalone analog dimming via its CTRL pin: applying 0.25V–1.35V sets LED current linearly from 0–100mV sense threshold, delivering 20:1 dimming range. No MCU is required-dimming can be implemented with a simple resistor divider from VREF (2V) or external DAC.
What thermal management considerations apply to the LT8391DJUFDM#WPBF in high-power LED designs?
The LT8391DJUFDM#WPBF's 28-pin UFDM package has θJA = 34°C/W and requires soldering the exposed thermal pad (Pin 29) directly to a solid ground plane. For 50W+ applications, a 2–4 cm² copper pour with ≥4 thermal vias (0.3mm diameter) is recommended. Junction temperature must remain ≤150°C; internal overtemperature protection activates above this threshold.
Does the LT8391DJUFDM#WPBF support PWM dimming at frequencies above 1kHz?
Yes. The LT8391DJUFDM#WPBF accepts PWM signals up to 20kHz without degradation in dimming linearity or current regulation. Its FAULT pin updates only during PWM high state and latches during low state, ensuring stable fault reporting even at high PWM frequencies used in flicker-free human-centric lighting.
LT8391DJUFDM#WPBF Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- -
- Package/Case:
- 28-WFQFN 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:
- 0V ~ 60V
- Current - Output / Channel:
- -
- Frequency:
- 150kHz ~ 650kHz
- Dimming:
- Analog, PWM
- Applications:
- Lighting
- Operating Temperature:
- -40°C ~ 150°C (TJ)
- Grade:
- Automotive
- Qualification:
- AEC-Q100
- Mounting Type:
- Surface Mount, Wettable Flank
- Supplier Device Package:
- 28-QFN (4x5)
LT8391DJUFDM#WPBF FAQ
1.How can I place an order for LT8391DJUFDM#WPBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LT8391DJUFDM#WPBF 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 LT8391DJUFDM#WPBF reliable?
The price and inventory of LT8391DJUFDM#WPBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LT8391DJUFDM#WPBF is usually 5 days.
3.What payment methods are accepted for LT8391DJUFDM#WPBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LT8391DJUFDM#WPBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LT8391DJUFDM#WPBF?
LT8391DJUFDM#WPBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LT8391DJUFDM#WPBF 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 LT8391DJUFDM#WPBF?
For technical support, including LT8391DJUFDM#WPBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LT8391DJUFDM#WPBF requirements.
6.How does Aetrix verify that LT8391DJUFDM#WPBF is sourced from the original manufacturer or authorized distributors?
All LT8391DJUFDM#WPBF 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 LT8391DJUFDM#WPBF meets industry standards.
7.What is the process for return or replacement of LT8391DJUFDM#WPBF?
All LT8391DJUFDM#WPBF units undergo pre-shipment inspection (PSI). If there is an issue with LT8391DJUFDM#WPBF, 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 LT8391DJUFDM#WPBF part is unused and in its original packaging.
Return procedure for LT8391DJUFDM#WPBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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