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Analog Devices Inc. LT3755EUD#PBF
- Part No.:
- LT3755EUD#PBF
- Manufacturer:
- Analog Devices Inc.
- Category:
- LED Drivers
- Package:
- 16-WFQFN Exposed Pad
- Datasheet:
-
LT3755EUD#PBF.pdf
- Description:
- IC LED DRIVER CTRLR PWM 16QFN
- Quantity:
- Payment:
- Shipping:
Inventory:3,752
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Product details
Overview
LT3755EUD#PBF from Analog Devices is a 40V input, 75V output constant-current LED controller IC designed to drive high-power LEDs in boost, buck, or buck-boost topologies. It features high-side current sensing (100mV threshold), 100kHz–1MHz adjustable switching frequency, and integrated 7.15V gate driver for external N-channel MOSFETs-enabling automotive headlamp drivers and industrial LED lighting systems.
For engineers reviewing the LT3755EUD#PBF datasheet, LT3755EUD#PBF pinout, LT3755EUD#PBF application, or LT3755EUD#PBF equivalent, key selection considerations include its AEC-Q100 qualification, 3000:1 PWM dimming capability, open-LED protection via FB-based fault detection, and compatibility with thermally enhanced 3mm × 3mm QFN packaging.
Technical Context
The LT3755EUD#PBF implements fixed-frequency current-mode control with internal slope compensation, enabling stable regulation across wide VIN (4.5V–40V) and VOUT (up to 75V) ranges. Its dual-loop architecture supports simultaneous constant-current (via ISP/ISN) and constant-voltage (via FB) regulation, with independent thresholds: 100mV for LED current sense and 1.25V for FB voltage feedback.
High-side current sensing enables flexible topology deployment without ground-referenced load constraints. The CTRL pin provides analog dimming by scaling the ISP–ISN current threshold from 0V to 1.1V, while PWM input delivers true-color dimming up to 3000:1. Internal 7.15V INTVCC regulator powers gate and PWMOUT drivers, with thermal shutdown and undervoltage lockout (1.22V falling threshold) for robust operation.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 4.5V to 40V - supports 12V/24V automotive and industrial rails with margin for transients |
| Output Voltage Capability | Up to 75V - enables series strings of high-brightness white LEDs (e.g., 20× 3.5V) |
| Current Sense Threshold | 100mV (typical) at ISP–ISN - sets LED current with minimal power loss in sense resistor |
| Switching Frequency Range | 100kHz to 1MHz - programmable via RT pin to optimize efficiency vs. magnetics size |
| FB Regulation Voltage | 1.25V (nominal) - precise reference for constant-voltage loop and open-LED detection |
| INTVCC Regulator | 7.15V (typical), 34mA current limit - powers gate driver and logic; requires 4.7µF local bypass |
| Shutdown Current | <1µA - enables ultra-low-power standby in battery-powered LED systems |
Pinout & Package
LT3755EUD#PBF uses a thermally enhanced 16-lead (3mm × 3mm) plastic QFN package with exposed pad (Pin 17) soldered to PCB ground for thermal and electrical performance. Pin numbering follows standard top-view layout with GND on Pin 17.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| PWMOUT (Pin 1) | Buffered PWM output | Drives NMOS disconnect switch; toggles low during FB overvoltage (>VFB + 60mV) to protect LEDs |
| FB (Pin 2) | Voltage feedback input | Ground-referenced node for CV regulation and open-LED detection (asserts OPENLED when FB < VFB – 50mV) |
| ISN (Pin 3) | Negative current sense input | High-side current sense return; enables short-circuit detection when ISN < 3V |
| ISP (Pin 4) | Positive current sense input | High-side current sense high terminal; bias current varies with CTRL voltage |
| VC (Pin 5) | Error amplifier output | Integrates error signal for loop stability; high-impedance during PWM low to retain state |
| CTRL (Pin 6) | Analog dimming control | Scales ISP–ISN current threshold from 0V to 1.1V; enables linear current adjustment |
| VREF (Pin 7) | 2V reference output | Stable 2.00V source for CTRL divider or temperature compensation networks |
| PWM (Pin 8) | Digital dimming input | Active-high enable; controls switching and latches OPENLED status during idle |
| OPENLED (Pin 9) | Open-LED fault indicator | Open-collector pull-down asserted when FB drops below VFB – 50mV (LT3755/LT3755-2 only) |
| SS (Pin 10) | Soft-start control | 10µA pull-up to 2.5V rail; external capacitor sets startup ramp time |
| RT (Pin 11) | Frequency programming | Resistor-to-GND sets oscillator frequency; 100kΩ = ~100kHz, 10kΩ = ~1MHz |
| SHDN/UVLO (Pin 12) | Enable & undervoltage detect | 1.22V falling threshold with programmable hysteresis; resets soft-start on UV event |
| INTVCC (Pin 13) | Internal LDO output | 7.15V regulated supply for gate/PWMOUT drivers; must be bypassed with 4.7µF ceramic |
| VIN (Pin 14) | Main input supply | 4.5V–40V input; requires local 0.22µF+ ceramic bypass near pin |
| SENSE (Pin 15) | Low-side current sense | Kelvin-connected to FET source; monitors switch current for peak-current mode control |
| GATE (Pin 16) | NMOS gate driver | Swings between INTVCC and GND; drives external power FET with 35ns rise/fall times |
| Exposed Pad (Pin 17) | Thermal & electrical ground | Mandatory solder connection to PCB ground plane for thermal dissipation and noise immunity |
Key Features
| Feature | Design Value |
|---|---|
| High-side current sensing | Enables boost/buck/buck-boost/SEPIC/flyback topologies without load grounding constraints |
| 3000:1 True Color PWM™ dimming | Maintains LED color fidelity across full dimming range via precise timing-controlled duty cycle |
| AEC-Q100 qualified | Validated for automotive applications including headlamps, interior lighting, and ADAS displays |
| Programmable open-LED protection | FB-based fault detection with configurable threshold (VFB – 50mV) and latched status reporting |
| Adjustable frequency with RT pin | Allows trade-off between efficiency (lower fSW) and component size (higher fSW) without redesign |
| Integrated 7.15V gate driver | Eliminates need for external level-shifting circuitry when driving N-channel MOSFETs |
Applications
| Automotive LED Headlamps | Industrial High-Bay Lighting |
|---|---|
Use Scenario: 50W white LED headlamp driver in 12V/24V vehicle electrical system with EMI-sensitive cabin electronics. IC Role / Device Role / Timing Role: Constant-current controller managing boost converter to drive 12–18 LED series string; regulates current to ±3% over temperature and line variation. Use Value: AEC-Q100 qualification ensures reliability under automotive thermal cycling; 3000:1 PWM dimming enables adaptive driving beam (ADB) functionality without color shift. | Use Scenario: High-efficiency 100W LED fixture for warehouse ceiling mounting with 0–10V analog dimming interface. IC Role / Device Role / Timing Role: Buck-mode LED driver regulating current to 1.5A across 40–70V LED string; uses CTRL pin for smooth 0–10V analog dimming. Use Value: High-side sensing allows direct connection to grounded LED string; 100kHz–1MHz frequency tuning minimizes magnetic size while meeting EN55015 conducted EMI limits. |
| Battery-Powered Emergency Lighting | UV-C LED Disinfection Systems |
Use Scenario: Self-contained emergency exit sign powered by sealed lead-acid battery with 8–14V discharge profile. IC Role / Device Role / Timing Role: Boost converter controller maintaining constant 350mA LED current as battery voltage drops from 12.8V to 8.5V. Use Value: Ultra-low shutdown current (<1µA) extends battery life during standby; programmable UVLO prevents deep discharge damage. | Use Scenario: Pulsed UV-C LED array (275nm) for surface disinfection requiring precise current control and thermal derating. IC Role / Device Role / Timing Role: Constant-current source driving parallel UV-C LED strings with real-time thermal foldback via CTRL pin. Use Value: VREF output powers external thermistor network; CTRL pin adjusts current threshold to reduce LED drive as junction temperature rises. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar LED controller applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LTC3783EFE#PBF | Fixed 500kHz frequency; no RT pin; includes internal MOSFET drivers for synchronous rectification | Better suited for compact, lower-power designs where fixed frequency simplifies EMI filtering | Select when board space is constrained and 500kHz operation meets efficiency targets |
| LM3410XSD/NOPB | Lower max input (20V); integrated 1.5A MOSFET; no high-side current sensing or OPENLED pin | Targeted at portable LED flashlights and indicator lighting, not high-power automotive systems | Choose only for sub-20W applications with simpler protection requirements |
Compared with LTC3783EFE#PBF and LM3410XSD/NOPB, the LT3755EUD#PBF offers wider input range (4.5V–40V), programmable frequency, and dedicated open-LED fault signaling-making it uniquely suitable for AEC-Q100-compliant, high-reliability LED drivers demanding flexible topology and robust diagnostics.
Availability
LT3755EUD#PBF is available at Aetrix Electronics and suitable for automotive LED headlamps, industrial high-bay lighting, and battery-powered emergency signage requiring stable component supply and long-term lifecycle support.
Supply support for LT3755EUD#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 is a global leader in high-performance analog, mixed-signal, and digital signal processing semiconductors, serving industrial, automotive, communications, and healthcare markets.
The LT3755EUD#PBF belongs to Analog Devices' Power by Linear™ LED controller family, engineered specifically for high-efficiency, high-reliability constant-current LED drivers in demanding environments including automotive lighting and industrial illumination.
FAQ
What is the maximum output voltage supported by the LT3755EUD#PBF?
The LT3755EUD#PBF supports output voltages up to 75V, enabling it to drive long series strings of high-brightness LEDs. This capability is critical for automotive headlamp applications where 15–20 white LEDs (3.5V each) require ~60–70V total forward voltage. The controller achieves this through high-side current sensing and robust gate drive, not internal voltage rating-external components (inductor, diode, capacitor) must be rated accordingly.
Does the LT3755EUD#PBF support both constant-current and constant-voltage regulation?
Yes, the LT3755EUD#PBF supports dual-loop regulation: constant-current via ISP/ISN differential sensing (100mV threshold) and constant-voltage via FB pin (1.25V reference). When FB is used, the IC regulates output voltage; when ISP/ISN is active, it regulates LED current. Both loops coexist-the FB loop dominates during open-LED faults, while the current loop governs normal operation. Connecting FB to GND disables CV mode entirely.
How does the OPENLED pin function on the LT3755EUD#PBF?
The OPENLED pin on the LT3755EUD#PBF is an open-collector output that pulls low when the FB voltage falls below VFB – 50mV (typically 1.20V), indicating an open LED string. It requires an external pull-up resistor (<1mA current). During PWM low periods, the state is latched; it updates only when PWM goes high again. This pin is present on LT3755 and LT3755-2 variants-but replaced by SYNC on LT3755-1-so LT3755EUD#PBF (standard version) includes functional OPENLED reporting.
What package type and thermal characteristics does the LT3755EUD#PBF use?
The LT3755EUD#PBF uses a 16-lead 3mm × 3mm plastic QFN package with exposed thermal pad (Pin 17). Its thermal resistance is θJA = 68°C/W and θJC = 4.2°C/W. The exposed pad must be soldered to a PCB ground plane for effective heat dissipation. This package supports operation from –40°C to +125°C junction temperature and is rated for automotive-grade reliability per AEC-Q100.
Can the LT3755EUD#PBF be synchronized to an external clock?
No, the LT3755EUD#PBF does not support external synchronization. Synchronization capability is exclusive to the LT3755-1 variant (e.g., LT3755EUD-1#PBF), which replaces the OPENLED pin with a SYNC input. The LT3755EUD#PBF is the base version with OPENLED functionality and no SYNC pin. For designs requiring clock synchronization, the LT3755EUD-1#PBF or LT3755EUD-2#PBF (which adds improved OPENLED behavior) should be selected instead.
LT3755EUD#PBF Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- -
- Package/Case:
- 16-WFQFN Exposed Pad
- Packaging:
- Tube
- Product Status:
- Active
- Type:
- DC DC Controller
- Topology:
- Flyback, SEPIC, Step-Down (Buck), Step-Up (Boost)
- Internal Switch(s):
- No
- Number of Outputs:
- 1
- Voltage - Supply (Min):
- 4.5V
- Voltage - Supply (Max):
- 40V
- Voltage - Output:
- -
- Current - Output / Channel:
- -
- Frequency:
- 100kHz ~ 1MHz
- Dimming:
- Analog, PWM
- Applications:
- -
- Operating Temperature:
- 0°C ~ 125°C (TJ)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 16-QFN (3x3)
LT3755EUD#PBF FAQ
1.How can I place an order for LT3755EUD#PBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LT3755EUD#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 LT3755EUD#PBF reliable?
The price and inventory of LT3755EUD#PBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LT3755EUD#PBF is usually 5 days.
3.What payment methods are accepted for LT3755EUD#PBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LT3755EUD#PBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LT3755EUD#PBF?
LT3755EUD#PBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LT3755EUD#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 LT3755EUD#PBF?
For technical support, including LT3755EUD#PBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LT3755EUD#PBF requirements.
6.How does Aetrix verify that LT3755EUD#PBF is sourced from the original manufacturer or authorized distributors?
All LT3755EUD#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 LT3755EUD#PBF meets industry standards.
7.What is the process for return or replacement of LT3755EUD#PBF?
All LT3755EUD#PBF units undergo pre-shipment inspection (PSI). If there is an issue with LT3755EUD#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 LT3755EUD#PBF part is unused and in its original packaging.
Return procedure for LT3755EUD#PBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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