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Analog Devices Inc. LT3755IMSE#PBF
- Part No.:
- LT3755IMSE#PBF
- Manufacturer:
- Analog Devices Inc.
- Category:
- LED Drivers
- Package:
- 16-TFSOP (0.118", 3.00mm Width) Exposed Pad
- Datasheet:
-
LT3755IMSE#PBF.pdf
- Description:
- IC LED DRIVER CTRLR PWM 16MSOP
- Quantity:
- Payment:
- Shipping:
Inventory:111
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Product details
Overview
LT3755IMSE#PBF 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#PBF datasheet, LT3755IMSE#PBF pinout, LT3755IMSE#PBF application, or LT3755IMSE#PBF equivalent, key selection criteria include high-side current sense architecture, programmable 100kHz–1MHz switching frequency, open LED protection via FB-based fault detection, and thermally enhanced MSOP-16 packaging with exposed pad grounding.
Technical Context
The LT3755IMSE#PBF implements fixed-frequency current-mode control with internal 7.15V INTVCC regulation, enabling stable operation across wide VIN (4.5V–40V) and VOUT (up to 75V) ranges. Its ground-referenced FB pin supports dual-mode regulation-constant-current via ISP/ISN differential sensing and constant-voltage via FB feedback-with seamless interaction between loops.
High-side current sensing at ISP/ISN (common-mode range 2.9V–75V) allows topology flexibility and avoids ground path disruption. The CTRL pin adjusts current threshold from 0V to 1.1V, scaling V(ISP–ISN) from 0mV to 100mV; PWM input controls switcher enable/disable and drives PWMOUT for external NMOS disconnect.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 4.5V to 40V - supports 12V/24V automotive systems and industrial supplies without external regulators |
| Output Voltage Capability | Up to 75V - enables single-string or multi-series white LED arrays (e.g., 20×3.2V) |
| Current Sense Threshold | 100mV (typical) at ISP–ISN - sets LED current ILED = 100mV/RSENSE, minimizing power loss in sense resistor |
| Switching Frequency Range | 100kHz to 1MHz - adjustable via RT resistor to optimize efficiency vs. magnetics size (e.g., 375kHz typical for 50W headlamp) |
| Dimming Ratio | 3000:1 true-color PWM - preserves LED chromaticity across full brightness range using dedicated PWM input |
| Operating Junction Temp | –40°C to +125°C - qualified per AEC-Q100 Grade I, suitable for under-hood automotive environments |
| Package Thermal Resistance | θJA = 43°C/W (MSOP) - requires exposed pad soldered to PCB ground plane for reliable thermal dissipation |
Pinout & Package
LT3755IMSE#PBF uses a 16-lead plastic MSOP package with exposed pad (Pin 17), requiring soldering to PCB ground for thermal and electrical integrity. Pin numbering follows standard MSOP top-view layout (Pin 1 = VREF, Pin 16 = GATE).
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| VREF (Pin 1) | 2.0V reference output | Provides stable bias for CTRL divider or temperature compensation network; sources ≤100µA |
| PWM (Pin 2) | Enable/disable control input | Low disables oscillator, forces GATE/PWMOUT low, and places VC in high-Z storage mode |
| OPENLED (Pin 3) | Open-circuit fault indicator | Pull-down asserts when FB < (1.25V – 50mV); requires external <1mA pull-up for status reporting |
| SS (Pin 4) | Soft-start timing node | 10µA internal current charges external capacitor; reset by UVLO or thermal fault |
| FB (Pin 12) | Voltage loop feedback input | Regulates to 1.25V nominal; enables CV mode and open-LED detection; must not be left floating |
| GATE (Pin 16) | NMOS gate driver output | Swings between INTVCC (~7.15V) and GND; drives external low-side FET with 35ns rise/fall times |
| Exposed Pad (Pin 17) | Thermal & electrical ground | Must be soldered to PCB ground plane; serves as return path for SENSE current and improves θJA |
Key Features
| Feature | Design Value |
|---|---|
| High-side current sensing | Enables boost/buck/buck-boost topologies without disrupting ground return; ISP/ISN common-mode range extends to 75V |
| Programmable switching frequency | RT resistor sets 100kHz–1MHz range - allows trade-off between EMI, efficiency, and inductor size (e.g., 375kHz for 50W headlamp) |
| Dual-loop regulation | Simultaneous CC (ISP–ISN) and CV (FB) control with automatic dominance management - prevents overvoltage during open-LED fault |
| Integrated open-LED protection | FB-based detection triggers OPENLED pull-down at (1.25V – 50mV); de-asserts if FB exceeds (1.25V + 60mV) to prevent LED overcurrent |
| AEC-Q100 Grade I qualification | Validated for automotive applications including headlamps; operates reliably from –40°C to +125°C junction temperature |
Applications
| Automotive LED Headlamps | Battery-Powered LED Lighting |
|---|---|
Use Scenario: High-brightness forward lighting in passenger vehicles with adaptive beam control. IC Role / Device Role / Timing Role: Constant-current LED driver controlling 50W white LED string in boost configuration with PWM dimming. Use Value: 3000:1 dimming preserves color fidelity; AEC-Q100 qualification ensures reliability in under-hood thermal cycling. | Use Scenario: Portable work lights or emergency beacons powered by 12V lead-acid or Li-ion battery packs. IC Role / Device Role / Timing Role: Buck-mode LED driver regulating current across varying battery voltage (10V–14.4V) while maintaining consistent lumen output. Use Value: Wide 4.5V–40V input range accommodates deep discharge and charging transients; <1µA shutdown current extends battery life. |
| Industrial Machine Vision Lighting | Architectural LED Signage |
Use Scenario: High-intensity strobed illumination for high-speed camera inspection systems. IC Role / Device Role / Timing Role: Fast-response current source enabling precise PWM-controlled strobing at kHz rates with minimal latency. Use Value: Dedicated PWM input and PWMOUT driver support sub-microsecond turn-on/off; current-mode control ensures stable pulse amplitude. | Use Scenario: Multi-segment RGBW signage requiring independent current control per channel. IC Role / Device Role / Timing Role: Constant-current controller per LED string, configured in buck-boost topology to maintain regulation across varying bus voltage (24V–48V). Use Value: High-side sensing decouples current measurement from ground plane noise; 75V output supports long series strings in large-format displays. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar LED controller applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LT3756IMSE#PBF | Higher 60V ISP/ISN rating (vs. 75V), identical pinout and feature set; adds spread-spectrum modulation | Preferred for EMI-sensitive environments where spectral spreading reduces peak emissions | Select LT3756IMSE#PBF when regulatory compliance requires lower radiated emissions without changing layout |
| MAX16834ATP+ | Fixed 200kHz–2MHz frequency range; no CTRL pin for analog dimming; different pin assignment (e.g., no dedicated OPENLED) | Suitable for cost-sensitive industrial lighting where only PWM dimming and basic OVP are required | Choose MAX16834ATP+ when analog dimming and open-LED status reporting are not needed and higher max frequency is beneficial |
Compared with LT3756IMSE#PBF and MAX16834ATP+, the LT3755IMSE#PBF offers superior high-side sensing headroom (75V), integrated open-LED status signaling, and analog dimming via CTRL-making it optimal for automotive and precision lighting where fault visibility and flexible current programming are critical.
Availability
LT3755IMSE#PBF is available at Aetrix Electronics and suitable for automotive LED headlamps, battery-powered portable lighting, and industrial machine vision systems requiring stable component supply, AEC-Q100 compliance, and high-reliability thermal performance.
Supply support for LT3755IMSE#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 semiconductor leader specializing in high-performance analog, mixed-signal, and digital signal processing technologies for precision, power, and connectivity applications.
The LT3755 product line was designed specifically for high-efficiency, high-reliability LED driver applications in automotive, industrial, and architectural lighting-emphasizing robust fault protection, wide input/output capability, and topology flexibility.
FAQ
What is the maximum output voltage supported by the LT3755IMSE#PBF?
The LT3755IMSE#PBF supports output voltages up to 75V, enabling direct drive of long series-connected white LED strings (e.g., 20–23 LEDs at 3.2V each). This rating applies to the ISP and ISN pins' absolute maximum voltage and is validated in boost and flyback configurations per the datasheet's typical applications. The LT3755IMSE#PBF maintains stable current regulation across this full range when paired with appropriately rated external components.
Does the LT3755IMSE#PBF support both constant-current and constant-voltage regulation?
Yes, the LT3755IMSE#PBF supports dual-loop regulation: constant-current via high-side ISP–ISN sensing and constant-voltage via the FB pin referenced to 1.25V. When FB is used, the IC regulates output voltage; when ISP/ISN are active, it regulates LED current. The loops interact so that FB does not exceed 1.25V and ISP–ISN does not exceed the CTRL-set threshold - ensuring safe operation during open-LED faults. This behavior is intrinsic to the LT3755IMSE#PBF's error amplifier architecture.
How does the OPENLED pin function on the LT3755IMSE#PBF?
The OPENLED pin on the LT3755IMSE#PBF is an open-collector output that pulls down when the FB voltage falls below (1.25V – 50mV), indicating an open LED condition. It requires an external pull-up current <1mA. During PWM low/idle states, the last valid OPENLED state is latched. The LT3755IMSE#PBF re-evaluates OPENLED only when PWM goes high again. If FB exceeds (1.25V + 60mV), OPENLED is de-asserted and PWMOUT is driven low to protect LEDs - a safety feature unique to the LT3755IMSE#PBF.
What package type and thermal requirements apply to the LT3755IMSE#PBF?
The LT3755IMSE#PBF uses a 16-lead plastic MSOP package with exposed pad (Pin 17), specified for θJA = 43°C/W. The exposed pad must be soldered directly to the PCB ground plane to achieve rated thermal performance and ensure electrical stability. Failure to do so risks thermal runaway and premature failure. The LT3755IMSE#PBF's maximum junction temperature is +125°C, and its thermal design must account for power dissipation in INTVCC, GATE driver, and internal LDO circuits.
Can the LT3755IMSE#PBF be synchronized to an external clock?
No - the LT3755IMSE#PBF does not support external synchronization. That capability is exclusive to the LT3755-1 variant (e.g., LT3755IMSE-1#PBF), where Pin 3 is SYNC instead of OPENLED. On the LT3755IMSE#PBF, Pin 3 is OPENLED and lacks SYNC functionality. Attempting to drive an external clock signal into this pin will not synchronize the oscillator and may cause undefined behavior. For sync requirements, select the -1 version or verify part marking (37551) on the device body.
LT3755IMSE#PBF Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- -
- Package/Case:
- 16-TFSOP (0.118", 3.00mm Width) 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:
- -40°C ~ 125°C (TJ)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 16-MSOP-EP
LT3755IMSE#PBF FAQ
1.How can I place an order for LT3755IMSE#PBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LT3755IMSE#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 LT3755IMSE#PBF reliable?
The price and inventory of LT3755IMSE#PBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LT3755IMSE#PBF is usually 5 days.
3.What payment methods are accepted for LT3755IMSE#PBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LT3755IMSE#PBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LT3755IMSE#PBF?
LT3755IMSE#PBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LT3755IMSE#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 LT3755IMSE#PBF?
For technical support, including LT3755IMSE#PBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LT3755IMSE#PBF requirements.
6.How does Aetrix verify that LT3755IMSE#PBF is sourced from the original manufacturer or authorized distributors?
All LT3755IMSE#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 LT3755IMSE#PBF meets industry standards.
7.What is the process for return or replacement of LT3755IMSE#PBF?
All LT3755IMSE#PBF units undergo pre-shipment inspection (PSI). If there is an issue with LT3755IMSE#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 LT3755IMSE#PBF part is unused and in its original packaging.
Return procedure for LT3755IMSE#PBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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