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Analog Devices Inc. LT3755IMSE-1#PBF
- Part No.:
- LT3755IMSE-1#PBF
- Manufacturer:
- Analog Devices Inc.
- Category:
- LED Drivers
- Package:
- 16-TFSOP (0.118", 3.00mm Width) Exposed Pad
- Datasheet:
-
LT3755IMSE-1#PBF.pdf
- Description:
- IC LED DRIVER CTRLR PWM 16MSOP
- Quantity:
- Payment:
- Shipping:
Inventory:154
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Product details
Overview
LT3755IMSE-1#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 frequency synchronization (via SYNC pin) for noise-sensitive automotive lighting systems.
For engineers reviewing the LT3755IMSE-1#PBF datasheet, LT3755IMSE-1#PBF pinout, LT3755IMSE-1#PBF application, or LT3755IMSE-1#PBF equivalent, key selection criteria include its AEC-Q100 qualification, 16-lead MSOP package with exposed pad, SYNC-enabled clock alignment, open LED protection, and compatibility with high-power white LED headlamp drivers requiring precise constant-current regulation.
Technical Context
The LT3755IMSE-1#PBF implements fixed-frequency current-mode control with internal 7.15V INTVCC regulator powering gate and PWMOUT drivers. Its dual-loop architecture simultaneously manages high-side current sense (ISP/ISN) for LED current regulation and ground-referenced FB for voltage loop control or open-LED fault detection.
Unlike the base LT3755 or LT3755-2 variants, the -1 suffix denotes integrated frequency synchronization capability via dedicated SYNC pin (replacing OPENLED), enabling deterministic timing alignment with external clocks - critical for EMI reduction in multi-phase or multi-lamp automotive systems.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 4.5V to 40V - supports wide automotive battery range including cold-crank (6V) and load-dump (36V+) |
| Max Output Voltage | 75V - enables series strings of high-brightness white LEDs (e.g., 20× 3.5V LEDs) |
| 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 (programmable via RT resistor) - allows trade-off between efficiency (lower f) and magnetics size (higher f) |
| Synchronization Support | SYNC pin accepts external logic-level clock - enables phase-aligned operation across multiple LT3755IMSE-1#PBF controllers to suppress beat frequencies |
| Operating Temperature | –40°C to +125°C (I-grade) - qualified for under-hood automotive environments per AEC-Q100 |
| Package | 16-lead MSOP with exposed thermal pad - provides low θJA = 43°C/W for thermally demanding LED driver PCB layouts |
Pinout & Package
LT3755IMSE-1#PBF uses a 16-lead plastic MSOP package (3mm × 4.9mm) with exposed pad (Pin 17) soldered to PCB ground for thermal and electrical integrity. Pin numbering follows standard MSOP top-view orientation.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| PWMOUT (Pin 11) | Buffered PWM output | Drives NMOS disconnect switch or level-shifter; toggles low during FB overvoltage (> VFB + 60mV) to protect LEDs |
| FB (Pin 12) | Voltage feedback input | Regulates output voltage to 1.25V reference; enables open-LED detection when FB > VFB – 50mV |
| ISN (Pin 13) | Negative current sense input | High-side current sense return; enables short-circuit detection if ISP–ISN > 150mV below 3V common-mode |
| ISP (Pin 14) | Positive current sense input | Connects to high-side of LED string sense resistor; bias current varies with CTRL voltage |
| VC (Pin 15) | Error amplifier output | Integrates difference between ISP–ISN and CTRL-set threshold; requires RC compensation network to GND |
| CTRL (Pin 16) | Current threshold adjust | Programs LED current sense threshold: 100mV (full scale) when VCTRL ≥ 1.2V; linear scaling below 1V |
| VREF (Pin 1) | 2.0V reference output | Stable 2.0V source (±2%) for CTRL divider or temperature compensation networks; supplies ≤100µA |
| PWM (Pin 2) | Digital dimming input | Active-high signal enabling 3000:1 true-color PWM dimming; internal pull-down allows direct MCU GPIO connection |
| SYNC (Pin 3) | Frequency sync input | Replaces OPENLED on -1 variant; synchronizes internal oscillator to external clock (20% slower RT setting required) |
| SS (Pin 4) | Soft-start control | 10µA internal pull-up to 2.5V rail; external capacitor sets ramp time; reset by UVLO or thermal fault |
| RT (Pin 5) | Frequency programming | Resistor-to-GND sets switching frequency (100kΩ → ~100kHz; 10kΩ → ~1MHz); no internal pull-up |
| SHDN/UVLO (Pin 6) | Shutdown & undervoltage detect | 1.22V falling threshold with programmable hysteresis; sub-µA shutdown current (<1µA) when pulled ≤0.4V |
| INTVCC (Pin 7) | Internal LDO output | 7.15V regulated supply (±150mV) for gate/PWMOUT drivers; requires 4.7µF ceramic bypass close to pin |
| VIN (Pin 8) | Main input supply | Accepts 4.5V–40V; local 0.22µF+ ceramic bypass mandatory; powers INTVCC LDO and internal logic |
| SENSE (Pin 9) | Low-side current sense | Kelvin-connected to source of external NMOS sense resistor; monitors switch current for slope-compensated current mode control |
| GATE (Pin 10) | MOSFET gate driver | Drives external N-channel FET between INTVCC and GND; 35ns rise/fall into 3300pF; clamped during fault/shutdown |
| Exposed Pad (Pin 17) | Thermal & electrical ground | Must be soldered to PCB ground plane; reduces θJA by >20°C/W and improves EMI performance |
Key Features
| Feature | Design Value |
|---|---|
| Frequency Synchronization | SYNC pin enables deterministic clock alignment across multiple controllers - eliminates beat frequencies in multi-lamp systems |
| AEC-Q100 Qualified | I-grade (–40°C to +125°C) operation with production test flow meeting automotive reliability standards |
| High-Side Current Sensing | ISP/ISN inputs support flexible topology selection (boost/buck/buck-boost/SEPIC/flyback) without ground-loop interference |
| True Color PWM Dimming | 3000:1 dimming ratio preserves LED chromaticity - essential for adaptive front-lighting systems (AFS) |
| Integrated Protection Suite | Open-LED detection, ISP/ISN short-circuit sensing, FB overvoltage shutdown, thermal foldback, and undervoltage lockout |
| Low Shutdown IQ | <1µA shutdown current - extends battery life in always-on vehicle modules (e.g., daytime running lights) |
Applications
| Automotive LED Headlamps | Battery-Powered LED Lighting |
|---|---|
Use Scenario: High-intensity white LED arrays in adaptive front-lighting systems (AFS) requiring precise current regulation and EMI-controlled switching. IC Role / Device Role / Timing Role: Constant-current controller managing boost converter topology with synchronized switching to meet CISPR-25 Class 5 radiated emissions limits. Use Value: SYNC pin enables phase alignment across multiple LT3755IMSE-1#PBF units, reducing peak EMI by >10dB compared to free-running operation. | Use Scenario: Portable medical devices or handheld inspection tools using high-brightness LEDs powered by Li-ion batteries (3.0–4.2V). IC Role / Device Role / Timing Role: Buck-mode LED driver regulating current despite varying battery voltage, with soft-start preventing inrush into capacitive loads. Use Value: 4.5V minimum VIN allows operation down to near-end-of-discharge battery levels while maintaining stable LED brightness. |
| Industrial Machine Vision Lighting | Architectural LED Strips |
Use Scenario: Stroboscopic high-CRI LED arrays used in automated optical inspection (AOI) systems requiring microsecond-accurate flash timing. IC Role / Device Role / Timing Role: PWM-controlled constant-current source delivering repeatable light pulses synchronized to camera trigger signals via SYNC input. Use Value: 3000:1 PWM dimming range enables fine-grained intensity control without color shift - critical for spectral consistency in color measurement. | Use Scenario: Long linear LED strips (e.g., 24V input, 72V string) in commercial signage requiring uniform brightness and thermal derating. IC Role / Device Role / Timing Role: Boost-mode controller with open-LED protection ensuring fail-safe operation when individual LEDs fail open-circuit. Use Value: FB pin monitoring enables automatic shutdown upon open-string detection, preventing overvoltage stress on remaining LEDs and driver components. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar LED controller applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LT3755IMSE#PBF | Lacks SYNC pin; OPENLED pin present instead - no frequency synchronization capability | Suitable for single-channel, non-synchronized LED drivers where open-fault reporting is prioritized over EMI control | Select when system-level clock alignment is unnecessary and open-LED status signaling is required |
| LT3755IMSE-2#PBF | Includes enhanced OPENLED status pin with re-assertion logic after overvoltage recovery - no SYNC functionality | Optimized for safety-critical lighting where reliable open-load detection and fault latching are mandatory | Select for ASIL-B compliant designs requiring robust fault reporting without synchronization needs |
Compared with LT3755IMSE#PBF and LT3755IMSE-2#PBF, the LT3755IMSE-1#PBF uniquely provides frequency synchronization for EMI-sensitive multi-controller systems, trading open-LED reporting for deterministic timing - making it the only choice for synchronized automotive headlamp clusters.
Availability
LT3755IMSE-1#PBF is available at Aetrix Electronics and suitable for automotive LED headlamps, battery-powered portable lighting, industrial machine vision systems, and architectural LED strip drivers requiring stable component supply, AEC-Q100 compliance, and EMI-controlled switching performance.
Supply support for LT3755IMSE-1#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 LT3755 family is designed specifically for high-efficiency, high-reliability LED current regulation in demanding environments - with the -1 variant optimized for synchronized multi-channel automotive lighting applications.
FAQ
What is the primary function of the SYNC pin on the LT3755IMSE-1#PBF?
The SYNC pin on the LT3755IMSE-1#PBF accepts an external logic-level clock signal to synchronize the internal oscillator, enabling deterministic phase alignment across multiple LT3755IMSE-1#PBF controllers. This reduces beat frequencies and peak radiated EMI - a critical requirement for automotive LED headlamp clusters. The RT resistor must be set for an internal frequency ~20% slower than the SYNC signal frequency.
How does the LT3755IMSE-1#PBF differ from the standard LT3755IMSE#PBF?
The LT3755IMSE-1#PBF replaces the OPENLED pin with a SYNC pin, removing open-LED fault reporting capability but adding frequency synchronization. Both share identical current-sense architecture, 4.5V–40V input range, 75V output capability, and AEC-Q100 I-grade qualification. The LT3755IMSE-1#PBF is selected when EMI control via clock alignment outweighs the need for open-load status signaling.
Can the LT3755IMSE-1#PBF operate in buck configuration?
Yes, the LT3755IMSE-1#PBF supports buck, boost, buck-boost, SEPIC, and flyback topologies via high-side current sensing at ISP/ISN. In buck mode, the LED string connects between input and switch node, with ISP tied to the switch node and ISN to the LED cathode. The controller regulates LED current regardless of topology, leveraging its dual-loop architecture for stability and protection.
What is the maximum recommended switching frequency for the LT3755IMSE-1#PBF?
The LT3755IMSE-1#PBF supports up to 1MHz switching frequency, set by the RT resistor value (10kΩ typical). At 1MHz, gate drive losses and INTVCC loading increase - verify INTVCC current (IINTVCC = QG × fOSC) remains within the 34mA limit. For thermally constrained layouts, 300–500kHz offers optimal balance of efficiency, size, and thermal performance.
Does the LT3755IMSE-1#PBF require external compensation components?
Yes, the LT3755IMSE-1#PBF requires external RC compensation on the VC pin to stabilize the current and voltage loops. A series RC network (e.g., 10kΩ + 1nF) from VC to GND is typical. The exact values depend on chosen topology, output capacitance, and desired transient response - refer to Analog Devices' application notes (e.g., AN137) for design examples specific to the LT3755IMSE-1#PBF.
LT3755IMSE-1#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-1#PBF FAQ
1.How can I place an order for LT3755IMSE-1#PBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LT3755IMSE-1#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-1#PBF reliable?
The price and inventory of LT3755IMSE-1#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-1#PBF is usually 5 days.
3.What payment methods are accepted for LT3755IMSE-1#PBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LT3755IMSE-1#PBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LT3755IMSE-1#PBF?
LT3755IMSE-1#PBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LT3755IMSE-1#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-1#PBF?
For technical support, including LT3755IMSE-1#PBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LT3755IMSE-1#PBF requirements.
6.How does Aetrix verify that LT3755IMSE-1#PBF is sourced from the original manufacturer or authorized distributors?
All LT3755IMSE-1#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-1#PBF meets industry standards.
7.What is the process for return or replacement of LT3755IMSE-1#PBF?
All LT3755IMSE-1#PBF units undergo pre-shipment inspection (PSI). If there is an issue with LT3755IMSE-1#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-1#PBF part is unused and in its original packaging.
Return procedure for LT3755IMSE-1#PBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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