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Analog Devices Inc. LT3755IMSE#TRPBF
- Part No.:
- LT3755IMSE#TRPBF
- Manufacturer:
- Analog Devices Inc.
- Category:
- LED Drivers
- Package:
- 16-TFSOP (0.118", 3.00mm Width) Exposed Pad
- Datasheet:
-
LT3755IMSE#TRPBF.pdf
- Description:
- IC LED DRIVER CTRLR PWM 16MSOP
- Quantity:
- Payment:
- Shipping:
Inventory:4,770
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Product details
Overview
LT3755IMSE#TRPBF from Analog Devices is a constant-frequency, current-mode DC/DC LED controller driving external N-channel MOSFETs in boost, buck, buck-boost, SEPIC, or flyback topologies. It delivers up to 75V output, supports 4.5V–40V input, provides 100mV high-side current sensing, enables 3000:1 PWM dimming, and features AEC-Q100 qualification for automotive headlamp drivers.
For engineers reviewing the LT3755IMSE#TRPBF datasheet, LT3755IMSE#TRPBF pinout, LT3755IMSE#TRPBF application, or LT3755IMSE#TRPBF equivalent, key selection considerations include high-side current sense architecture, programmable 100kHz–1MHz switching frequency, open LED protection with OPENLED status pin, adjustable undervoltage lockout, and thermally enhanced MSOP-16 packaging for automotive-grade thermal reliability.
Technical Context
The LT3755IMSE#TRPBF implements a fixed-frequency current-mode control architecture with internal 7.15V INTVCC regulator powering gate driver and logic. Its ground-referenced FB pin enables dual constant-current (via ISP/ISN) and constant-voltage regulation, while the CTRL pin adjusts current-sense threshold from 0V to 1.1V for analog dimming or temperature compensation.
High-side current sensing at ISP/ISN supports flexible topology configuration without ground loop interference. The device integrates short-circuit detection (150mV threshold below 3V ISN), overvoltage protection (FB > VFB + 60mV forces PWMOUT low), and open LED detection (FB < VFB – 50mV asserts OPENLED), all operating across –40°C to 125°C junction temperature range.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 4.5V to 40V - supports 12V/24V automotive battery rails with cold-crank margin |
| Output Voltage Capability | Up to 75V - enables single-string or multi-series white LED arrays for headlamps |
| Current Sense Threshold | 100mV (typical) - sets LED current via RSENSE = 0.1V / ILED, minimizing power loss |
| Switching Frequency Range | 100kHz to 1MHz - adjustable via RT resistor to optimize EMI, efficiency, or inductor size |
| Dimming Ratio | 3000:1 true-color PWM - preserves LED chromaticity across full brightness range |
| Operating Junction Temp | –40°C to 125°C - qualified per AEC-Q100 Grade I for under-hood automotive use |
| Package | 16-Lead Plastic MSOP - exposed pad enhances thermal dissipation in compact PCB layouts |
Pinout & Package
LT3755IMSE#TRPBF uses a thermally enhanced 16-lead plastic MSOP package with exposed pad (Pin 17) soldered to PCB ground plane for thermal management and current sense return path. Pin numbering follows standard MSOP top-view orientation.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| PWMOUT (Pin 1) | Buffered PWM output | Drives NMOS disconnect switch; toggles low during FB overvoltage fault to isolate LED load |
| FB (Pin 2) | Voltage feedback input | Regulates to 1.25V nominal; enables CV mode and open LED detection (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 input; common-mode range up to 75V supports boost configurations |
| VC (Pin 5) | Error amplifier output | Integrates error signal for loop stability; high-impedance during PWM low for state retention |
| CTRL (Pin 6) | Current threshold adjust | Sets ISP–ISN threshold from 0V to 1.1V for analog dimming or thermal compensation |
| VREF (Pin 7) | 2.0V reference output | Supplies 100µA max; used to bias CTRL divider or temperature-sensing network |
| PWM (Pin 8) | Digital dimming input | Active-low shutdown; internal pull-down; controls PWMOUT and oscillator enable |
| OPENLED (Pin 9) | Open LED status output | 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 yields ~375kHz |
| SHDN/UVLO (Pin 12) | Shutdown & UVLO input | 1.22V falling threshold with programmable hysteresis; sub-µA shutdown current |
| INTVCC (Pin 13) | Internal LDO output | 7.15V regulated supply for gate driver; requires 4.7µF local ceramic bypass |
| VIN (Pin 14) | Main input supply | Bypass with ≥0.22µF ceramic capacitor; powers INTVCC LDO and internal circuitry |
| SENSE (Pin 15) | Low-side current sense | Kelvin-connected to FET source; monitors switch current for slope-compensated 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 conduction and current sense return |
Key Features
| Feature | Design Value |
|---|---|
| High-side current sensing | Enables topology flexibility (boost/buck/buck-boost) without compromising ground-referenced LED cathode |
| Programmable switching frequency | 100kHz–1MHz via RT resistor allows EMI optimization and magnetic component size reduction |
| AEC-Q100 Grade I qualification | Validated for –40°C to 125°C operation in automotive lighting systems requiring long-term reliability |
| Integrated open LED and overvoltage protection | OPENLED pin signals disconnection; PWMOUT forced low during FB overvoltage prevents LED damage |
| Adjustable undervoltage lockout with hysteresis | External resistor divider sets precise start/stop thresholds to prevent brownout oscillation |
| 100mV current sense threshold | Minimizes power loss in sense resistor while maintaining noise immunity in high-current LED applications |
Applications
| Automotive LED Headlamps | Battery-Powered LED Lighting |
|---|---|
Use Scenario: 50W white LED headlamp driver in passenger vehicle front lighting system. IC Role / Device Role / Timing Role: Constant-current controller regulating high-brightness LED string in boost configuration with 3000:1 PWM dimming. Use Value: AEC-Q100 qualification ensures reliability under engine bay thermal stress; high-side sensing avoids ground loop interference with vehicle chassis. | Use Scenario: Portable work light powered by 12V sealed lead-acid or Li-ion battery pack. IC Role / Device Role / Timing Role: Buck-mode LED driver delivering stable current across wide input voltage range (10V–14.4V) during battery discharge. Use Value: 4.5V minimum VIN enables operation down to deeply discharged battery; low shutdown current (<1µA) preserves battery life during storage. |
| Industrial Machine Vision Lighting | Architectural LED Signage |
Use Scenario: High-intensity strobed LED array for industrial camera synchronization in automated inspection systems. IC Role / Device Role / Timing Role: Fast-response current controller enabling microsecond-level PWM dimming with precise timing alignment to camera shutter. Use Value: 3000:1 true-color PWM preserves spectral consistency across intensity levels; programmable soft-start prevents inrush current during rapid on/off cycling. | Use Scenario: Outdoor LED signage requiring high-voltage string drive and robust fault protection in variable ambient conditions. IC Role / Device Role / Timing Role: Boost-mode controller driving 20–30 white LEDs in series with open LED and overvoltage protection. Use Value: OPENLED pin provides real-time fault reporting to building management system; 75V output capability reduces string count and improves system efficiency. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar LED controller applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LTC3783EFE#TRPBF | Fixed 500kHz frequency; no RT pin; integrated gate driver with higher peak current (2A vs 1.5A); no OPENLED pin | Targeted at lower-EMI, fixed-frequency designs where programmability is not required; lacks open LED status reporting | Select when board space is constrained and fixed frequency suffices; verify absence of OPENLED does not impact system fault monitoring requirements |
| LM3410XSDX/NOPB | Single-ended boost-only topology; 3.3V–40V input; 1.215V FB reference; no high-side current sense; smaller SOT-23-6 package | Cost-sensitive, low-power (<5W) LED drivers where topology flexibility and automotive qualification are not needed | Choose for non-automotive, low-current applications where MSOP-16 footprint and AEC-Q100 are unnecessary |
Compared with LTC3783EFE#TRPBF and LM3410XSDX/NOPB, LT3755IMSE#TRPBF offers unique high-side current sensing, programmable frequency, OPENLED status reporting, and AEC-Q100 qualification-making it the only option suitable for demanding automotive headlamp and industrial high-reliability LED systems requiring topology flexibility and comprehensive fault protection.
Availability
LT3755IMSE#TRPBF is available at Aetrix Electronics and suitable for automotive LED headlamps, battery-powered portable lighting, and industrial machine vision systems requiring stable component supply, long-term lifecycle support, and AEC-Q100-compliant performance.
Supply support for LT3755IMSE#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 is a global leader in high-performance analog, mixed-signal, and digital signal processing semiconductors, serving industrial, automotive, communications, and healthcare markets.
The LT3755 product line was designed specifically for high-reliability, high-efficiency LED current regulation in automotive and industrial lighting, emphasizing topology flexibility, comprehensive protection, and AEC-Q100 compliance.
FAQ
What is the maximum output voltage supported by the LT3755IMSE#TRPBF?
The LT3755IMSE#TRPBF supports output voltages up to 75V, enabling direct drive of long LED strings in boost or SEPIC configurations. This rating is defined by the absolute maximum ISP/ISN voltage of 75V and is validated across the full –40°C to 125°C operating junction temperature range. The LT3755IMSE#TRPBF maintains stable current regulation even at 75V output when paired with appropriately rated external components including MOSFET, diode, and output capacitor.
Does the LT3755IMSE#TRPBF support both constant-current and constant-voltage regulation?
Yes, the LT3755IMSE#TRPBF supports dual regulation modes. Constant-current regulation is achieved using high-side current sensing at ISP/ISN pins with threshold set by CTRL pin voltage. Constant-voltage regulation uses the FB pin referenced to an internal 1.25V bandgap, allowing the device to regulate output voltage independently or provide open LED protection. Both loops operate simultaneously, with priority given to current regulation under normal LED load conditions.
What is the function of the OPENLED pin on the LT3755IMSE#TRPBF?
The OPENLED pin on the LT3755IMSE#TRPBF is an open-collector output that pulls low when the FB pin voltage falls below VFB – 50mV (typical), indicating an open LED condition. It requires an external pull-up resistor (<1mA current) and latches its state during PWM low periods. This pin is present on LT3755 and LT3755-2 variants but replaced by SYNC on LT3755-1. The LT3755IMSE#TRPBF corresponds to the base LT3755 variant and includes functional OPENLED reporting.
How is switching frequency programmed on the LT3755IMSE#TRPBF?
Switching frequency on the LT3755IMSE#TRPBF is programmed using an external resistor connected from the RT pin to ground. The relationship is approximately fSW ≈ 106/RRT(Ω) kHz, yielding 375kHz with a 26.7kΩ resistor. Frequency is adjustable from 100kHz to 1MHz, and the RT pin must not be left floating. The LT3755IMSE#TRPBF's frequency programming enables optimization of efficiency, EMI, and magnetic component size without changing IC or layout.
Is the LT3755IMSE#TRPBF qualified for automotive applications?
Yes, the LT3755IMSE#TRPBF is AEC-Q100 qualified for automotive applications. As an "I" grade part, it is specified for operation from –40°C to +125°C junction temperature and has undergone stress testing per AEC-Q100 Rev H requirements. The "IMSE" suffix denotes Industrial/Automotive temperature grade in MSOP package, and the device is widely deployed in automotive LED headlamp systems requiring high reliability under under-hood thermal and vibration conditions.
LT3755IMSE#TRPBF Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- -
- Package/Case:
- 16-TFSOP (0.118", 3.00mm Width) 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:
- -40°C ~ 125°C (TJ)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 16-MSOP-EP
LT3755IMSE#TRPBF FAQ
1.How can I place an order for LT3755IMSE#TRPBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LT3755IMSE#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 LT3755IMSE#TRPBF reliable?
The price and inventory of LT3755IMSE#TRPBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LT3755IMSE#TRPBF is usually 5 days.
3.What payment methods are accepted for LT3755IMSE#TRPBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LT3755IMSE#TRPBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LT3755IMSE#TRPBF?
LT3755IMSE#TRPBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LT3755IMSE#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 LT3755IMSE#TRPBF?
For technical support, including LT3755IMSE#TRPBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LT3755IMSE#TRPBF requirements.
6.How does Aetrix verify that LT3755IMSE#TRPBF is sourced from the original manufacturer or authorized distributors?
All LT3755IMSE#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 LT3755IMSE#TRPBF meets industry standards.
7.What is the process for return or replacement of LT3755IMSE#TRPBF?
All LT3755IMSE#TRPBF units undergo pre-shipment inspection (PSI). If there is an issue with LT3755IMSE#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 LT3755IMSE#TRPBF part is unused and in its original packaging.
Return procedure for LT3755IMSE#TRPBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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