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Analog Devices Inc. LT3755EUD-1#TRPBF
- Part No.:
- LT3755EUD-1#TRPBF
- Manufacturer:
- Analog Devices Inc.
- Category:
- LED Drivers
- Package:
- 16-WFQFN Exposed Pad
- Datasheet:
-
LT3755EUD-1#TRPBF.pdf
- Description:
- IC LED DRIVER CTRLR PWM 16QFN
- Quantity:
- Payment:
- Shipping:
Inventory:3,050
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Product details
Overview
LT3755EUD-1#TRPBF from Analog Devices is a constant-frequency, current-mode DC/DC LED controller designed to drive high-current LEDs in boost, buck, or buck-boost topologies. It features high-side current sensing (100 mV threshold), 100 kHz–1 MHz adjustable switching frequency, and integrated 7.15 V INTVCC regulator for gate driving - enabling 50 W automotive headlamp drivers with 3000:1 PWM dimming.
For engineers reviewing the LT3755EUD-1#TRPBF datasheet, LT3755EUD-1#TRPBF pinout, LT3755EUD-1#TRPBF application, or LT3755EUD-1#TRPBF equivalent, key selection criteria include its AEC-Q100 qualification, open LED protection via FB-based fault detection, SYNC pin for external clock synchronization, and thermally enhanced 3 mm × 3 mm QFN-16 package with exposed ground pad.
Technical Context
The LT3755EUD-1#TRPBF implements a fixed-frequency current-mode control architecture with internal slope compensation, supporting stable regulation across wide input (4.5 V–40 V) and output (up to 75 V) voltage ranges. Its dual-loop capability enables simultaneous constant-current (via ISP/ISN) and constant-voltage (via FB) operation, with independent analog dimming (CTRL pin) and true-color PWM dimming (PWM pin).
Unlike the base LT3755 and LT3755-2 variants, the LT3755EUD-1#TRPBF integrates a dedicated SYNC pin (Pin 9 in QFN) for external oscillator synchronization - replacing the OPENLED function - and maintains identical electrical specs including 108 mV SENSE threshold, 1.25 V FB reference, and 7.15 V INTVCC regulation.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 4.5 V to 40 V - supports 12 V/24 V automotive battery rails with undervoltage lockout hysteresis. |
| Output Voltage Capability | Up to 75 V - enables single-string or multi-string high-brightness LED configurations. |
| Switching Frequency Range | 100 kHz to 1 MHz - programmable via RT resistor to optimize efficiency, EMI, or inductor size. |
| Current Sense Threshold | 100 mV (typical) at ISP–ISN - enables precise high-side LED current regulation with minimal power loss. |
| INTVCC Regulator | 7.15 V ±0.15 V - powers gate driver and internal logic; requires 4.7 µF ceramic bypass capacitor. |
| Dimming Support | 3000:1 PWM + analog CTRL dimming - ensures flicker-free, color-stable LED intensity control. |
| Package & Thermal | 16-lead 3 mm × 3 mm QFN with exposed GND pad - θJA = 68°C/W; rated for –40°C to +125°C junction temperature. |
Pinout & Package
LT3755EUD-1#TRPBF is housed in a thermally enhanced 16-lead plastic QFN (3 mm × 3 mm) with exposed GND pad (Pin 17), requiring soldering to PCB ground plane for thermal and electrical performance.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| PWMOUT (Pin 1) | Buffered PWM output | Drives NMOS disconnect switch; toggles low during FB overvoltage (>1.31 V) to protect LEDs. |
| FB (Pin 2) | Voltage feedback input | Regulates to 1.25 V nominal; enables CV mode and open-LED fault detection (pulls OPENLED when FB < 1.20 V). |
| ISN (Pin 3) | Negative current sense input | High-side current sense return; enables short-circuit detection when ISN < 3 V and ISP–ISN > 150 mV. |
| ISP (Pin 4) | Positive current sense input | High-side current sense high terminal; bias current varies with CTRL voltage per datasheet TPC. |
| VC (Pin 5) | Error amplifier output | Integrates ISP–ISN vs CTRL error; high-impedance during PWM low to retain state for next cycle. |
| CTRL (Pin 6) | Analog dimming control | Sets LED current threshold: 100 mV (VCTRL ≥ 1.2 V) or linearly scaled (0–1 V range). |
| VREF (Pin 7) | 2 V reference output | Stable 2.00 V ±1.5% source; drives CTRL divider or temperature-compensation networks (≤100 µA load). |
| PWM (Pin 8) | Digital dimming input | Active-high enable; internally pulled down; controls soft-start reset and VC hold during idle. |
| SYNC (Pin 9) | External clock input | Replaces OPENLED on LT3755-1 variants; synchronizes oscillator to external 50% duty cycle signal. |
| SS (Pin 10) | Soft-start timing | 10 µA pull-up to 2.5 V rail; external capacitor sets startup ramp time and prevents inrush current. |
| RT (Pin 11) | Frequency programming | Resistor-to-GND sets oscillator frequency; 100 kΩ → ~1 MHz, 1 MΩ → ~100 kHz. |
| SHDN/UVLO (Pin 12) | Enable & input monitoring | 1.22 V falling threshold with programmable hysteresis; shuts down IC and resets SS below threshold. |
| INTVCC (Pin 13) | Internal LDO output | 7.15 V regulated supply for gate/PWMOUT drivers; must be bypassed with 4.7 µF ceramic capacitor. |
| VIN (Pin 14) | Main power input | Accepts 4.5–40 V; requires local 0.22 µF+ ceramic bypass near pin for stability. |
| SENSE (Pin 15) | Low-side switch current sense | Kelvin-connected to source of external N-MOSFET; monitors peak switch current for current-mode control. |
| GATE (Pin 16) | N-MOSFET gate driver | Swings between INTVCC and GND; drives external power FET; clamped to GND during shutdown/fault. |
| Exposed Pad (Pin 17) | Thermal & electrical GND | Must be soldered to PCB ground plane; serves as primary thermal path and current sense return. |
Key Features
| Feature | Design Value |
|---|---|
| High-side current sensing | Enables flexible topology selection (boost/buck/buck-boost/SEPIC/flyback) without ground-referenced LED strings. |
| SYNC pin for external clock sync | Allows deterministic EMI reduction and multi-phase coordination in systems with multiple LT3755EUD-1#TRPBF controllers. |
| AEC-Q100 qualified | Validated for automotive applications including headlamps, interior lighting, and ADAS illumination subsystems. |
| Programmable soft-start | Prevents inrush current and output overshoot using external capacitor on SS pin with 10 µA internal current source. |
| Open LED & overvoltage protection | FB-based fault detection asserts OPENLED (or disables PWMOUT) to isolate LEDs during open-circuit or overvoltage events. |
Applications
| Automotive LED Headlamps | Battery-Powered LED Lighting |
|---|---|
Use Scenario: High-intensity front lighting in passenger vehicles with adaptive beam shaping and dynamic leveling. IC Role / Device Role / Timing Role: Constant-current LED controller managing 50 W white LED string in boost configuration with 3000:1 PWM dimming. Use Value: AEC-Q100 qualification ensures reliability under automotive thermal cycling (-40°C to +125°C), while SYNC pin enables synchronized switching to reduce conducted EMI in crowded vehicle harnesses. | Use Scenario: Portable work lights, emergency beacons, and off-grid solar-powered signage requiring long runtime and stable brightness. IC Role / Device Role / Timing Role: Buck-mode LED driver regulating current from 12 V lead-acid or Li-ion battery packs across varying SOC (10–14 V). Use Value: Wide 4.5 V–40 V input range accommodates deep battery discharge; low 1 µA shutdown current extends battery life during standby. |
| Industrial Machine Vision Illumination | Architectural LED Accent Lighting |
Use Scenario: High-CRI, strobed LED arrays used in automated optical inspection systems requiring precise intensity repeatability. IC Role / Device Role / Timing Role: Constant-current controller operating in buck-boost mode to maintain 700 mA LED current despite ±15% input rail variation. Use Value: 100 mV high-side current sense minimizes power loss and improves accuracy; CTRL pin enables analog dimming for fine-grained intensity calibration. | Use Scenario: Linear LED strips and recessed fixtures in commercial buildings where thermal management and EMI compliance are critical. IC Role / Device Role / Timing Role: Boost-mode controller powering 24 V LED strings from 12 V distributed supply with programmable frequency to avoid AM radio band. Use Value: Adjustable 100 kHz–1 MHz switching frequency allows layout optimization for low EMI; exposed QFN pad ensures reliable thermal dissipation in enclosed fixtures. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar LED controller applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LT3755EUD#TRPBF | Lacks SYNC pin; includes OPENLED status output instead; identical current/voltage specs and package. | Better suited for systems requiring open-LED fault reporting rather than clock synchronization. | Select when fault signaling is prioritized over EMI control or multi-controller phase alignment. |
| LT3755EUD-2#TRPBF | Includes enhanced OPENLED latching behavior and improved short-circuit response; no SYNC pin. | Optimized for safety-critical LED loads where robust fault retention during PWM idle is required. | Choose for fail-safe lighting systems needing persistent open-LED indication after PWM deactivation. |
Compared with LT3755EUD#TRPBF and LT3755EUD-2#TRPBF, the LT3755EUD-1#TRPBF uniquely provides external clock synchronization - making it the only variant suitable for deterministic EMI reduction in multi-channel LED drivers - while retaining full AEC-Q100 qualification and identical thermal/current performance.
Availability
LT3755EUD-1#TRPBF is available at Aetrix Electronics and suitable for automotive LED headlamps, industrial machine vision lighting, and battery-powered portable illumination requiring stable component supply, AEC-Q100 compliance, and precise high-side current regulation.
Supply support for LT3755EUD-1#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. is a global leader in high-performance analog, mixed-signal, and digital signal processing semiconductors, serving industrial, automotive, communications, and healthcare markets.
The LT3755 family is part of Analog Devices' Power by Linear™ portfolio, engineered specifically for high-efficiency, high-reliability LED driver applications demanding wide input range, flexible topology support, and automotive-grade robustness.
FAQ
What is the key functional difference between LT3755EUD-1#TRPBF and LT3755EUD#TRPBF?
The LT3755EUD-1#TRPBF replaces the OPENLED pin (Pin 9) with a SYNC input for external clock synchronization, whereas the LT3755EUD#TRPBF retains OPENLED for open-LED fault reporting. All other electrical specifications, pinout (except Pin 9 function), package, and thermal ratings are identical between the two variants. This makes LT3755EUD-1#TRPBF the preferred choice when EMI reduction via synchronized switching is required.
Does LT3755EUD-1#TRPBF support both constant-current and constant-voltage regulation?
Yes, LT3755EUD-1#TRPBF supports dual-loop regulation: constant-current via high-side ISP/ISN sensing (100 mV threshold) and constant-voltage via FB pin (1.25 V reference). The two loops interact - e.g., FB overvoltage forces PWMOUT low to protect LEDs - but either can dominate depending on external resistor network configuration. For pure CC operation, tie FB to GND; for pure CV, tie ISP/ISN together and CTRL to VREF.
What is the minimum recommended capacitor value for the INTVCC pin on LT3755EUD-1#TRPBF?
The minimum recommended capacitor for the INTVCC pin on LT3755EUD-1#TRPBF is 4.7 µF, using a 10 V-rated X7R or X5R ceramic type with low ESR. This value ensures stable operation of the internal 7.15 V LDO under peak gate drive currents and prevents voltage droop during high-frequency switching. The capacitor must be placed as close as possible to the INTVCC pin and its ground connection to minimize loop inductance.
Can LT3755EUD-1#TRPBF operate from a 5 V input supply?
Yes, LT3755EUD-1#TRPBF can operate from a 5 V input supply. Its minimum operating VIN is specified at 4.5 V, and the internal INTVCC regulator remains functional down to this level. However, if VIN drops below 6 V, the SHDN/UVLO pin must not exceed VIN to ensure proper undervoltage detection. For 5 V operation, connect SHDN/UVLO directly to VIN or use a resistive divider referenced to VIN.
How does the CTRL pin affect LED current regulation in LT3755EUD-1#TRPBF?
The CTRL pin on LT3755EUD-1#TRPBF sets the target current sense threshold between ISP and ISN: for VCTRL ≥ 1.2 V, the threshold is fixed at 100 mV; for 0 V < VCTRL < 1 V, it scales linearly as (VCTRL – 0.1 V)/10; and for 1 V ≤ VCTRL ≤ 1.2 V, it transitions smoothly to full scale. This enables precise analog dimming without altering the LED string voltage or requiring additional DAC circuitry - a core feature of the LT3755EUD-1#TRPBF design.
LT3755EUD-1#TRPBF Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- -
- Package/Case:
- 16-WFQFN Exposed Pad
- Packaging:
- Tape & Reel (TR)
- 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-1#TRPBF FAQ
1.How can I place an order for LT3755EUD-1#TRPBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LT3755EUD-1#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 LT3755EUD-1#TRPBF reliable?
The price and inventory of LT3755EUD-1#TRPBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LT3755EUD-1#TRPBF is usually 5 days.
3.What payment methods are accepted for LT3755EUD-1#TRPBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LT3755EUD-1#TRPBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LT3755EUD-1#TRPBF?
LT3755EUD-1#TRPBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LT3755EUD-1#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 LT3755EUD-1#TRPBF?
For technical support, including LT3755EUD-1#TRPBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LT3755EUD-1#TRPBF requirements.
6.How does Aetrix verify that LT3755EUD-1#TRPBF is sourced from the original manufacturer or authorized distributors?
All LT3755EUD-1#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 LT3755EUD-1#TRPBF meets industry standards.
7.What is the process for return or replacement of LT3755EUD-1#TRPBF?
All LT3755EUD-1#TRPBF units undergo pre-shipment inspection (PSI). If there is an issue with LT3755EUD-1#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 LT3755EUD-1#TRPBF part is unused and in its original packaging.
Return procedure for LT3755EUD-1#TRPBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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