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Analog Devices Inc. LT3755EMSE-1#PBF
- Part No.:
- LT3755EMSE-1#PBF
- Manufacturer:
- Analog Devices Inc.
- Category:
- LED Drivers
- Package:
- 16-TFSOP (0.118", 3.00mm Width) Exposed Pad
- Datasheet:
-
LT3755EMSE-1#PBF.pdf
- Description:
- IC LED DRIVER CTRLR PWM 16MSOP
- Quantity:
- Payment:
- Shipping:
Inventory:100
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Product details
Overview
LT3755EMSE-1#PBF from Analog Devices is a constant-frequency, current-mode DC/DC LED controller in a 16-lead MSOP package, designed to drive high-current LEDs in boost, buck, or buck-boost topologies. It features 4.5V–40V input range, 75V output capability, 100kHz–1MHz adjustable switching frequency, high-side current sensing with 100mV threshold, and AEC-Q100 qualification for automotive headlamp drivers.
For engineers reviewing the LT3755EMSE-1#PBF datasheet, LT3755EMSE-1#PBF pinout, LT3755EMSE-1#PBF application, or LT3755EMSE-1#PBF equivalent, key selection criteria include its SYNC pin for external clock synchronization (distinguishing it from LT3755 and LT3755-2), 1.25V FB regulation voltage, 7.15V INTVCC regulator, open-LED fault reporting via OPENLED replacement by SYNC, and compatibility with thermally demanding automotive lighting designs requiring stable current regulation under wide VIN transients.
Technical Context
The LT3755EMSE-1#PBF implements fixed-frequency current-mode control with an internal 7.15V LDO powering the gate driver and logic. Its oscillator frequency is programmable via RT resistor (100kΩ → ~375kHz) and synchronizable to external clocks through the dedicated SYNC pin-replacing OPENLED functionality per variant specification.
High-side current sensing across ISP/ISN enables topology flexibility (boost/buck/buck-boost/SEPIC/flyback), while the CTRL pin adjusts current sense threshold from 0V to 1.1V, enabling analog dimming. The FB pin supports dual-mode operation: constant-current regulation via ISP/ISN feedback or constant-voltage regulation with 1.25V reference, with overvoltage protection triggering PWMOUT low at VFB + 60mV.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 4.5V to 40V - supports 12V/24V automotive battery systems with cold-crank margin down to 4.5V. |
| Output Voltage Capability | Up to 75V - enables driving long LED strings in headlamp and signage applications. |
| Switching Frequency Range | 100kHz to 1MHz - adjustable via RT resistor; 375kHz typical with 100kΩ, balancing efficiency and magnetics size. |
| Current Sense Threshold | 100mV nominal at ISP–ISN - enables precise high-side LED current regulation with minimal power loss in sense resistor. |
| INTVCC Regulator | 7.15V ±0.15V - powers gate driver and internal circuitry; requires 4.7µF local ceramic bypass for stability. |
| CTRL Pin Range | 0V to 1.1V - linearly scales current sense threshold from 0mV to full-scale 100mV, enabling analog dimming control. |
| SYNC Input Compatibility | Logic-level sync signal (1.5V high, 0.4V low) - allows deterministic phase alignment with system clocks or other converters. |
Pinout & Package
LT3755EMSE-1#PBF uses a thermally enhanced 16-lead plastic MSOP package (3mm × 4.9mm) with exposed pad soldered to PCB ground for thermal management. Pin 17 (exposed pad) is GND and mandatory 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 (VFB + 60mV) to protect LEDs. |
| FB (Pin 2) | Voltage feedback input | Regulates to 1.25V; enables constant-voltage mode and open-LED detection (threshold = VFB – 50mV). |
| ISN (Pin 3) | Negative current sense input | High-side current sense return; enables short-circuit detection when ISN < 3V and ISP–ISN > 150mV. |
| 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 error signal for loop stability; high-impedance during PWM low to retain state. |
| CTRL (Pin 6) | Current threshold adjust | Sets ISP–ISN threshold: 100mV when CTRL > 1.2V; linear scaling below 1V (e.g., 0.5V → 50mV). |
| VREF (Pin 7) | 2.0V reference output | Stable 2.0V source (±20mV) for CTRL biasing or temperature compensation networks; supplies ≤100µA. |
| PWM (Pin 8) | Dimming enable input | Active-high digital dimming control; internal pull-down; 3000:1 PWM dimming ratio supported. |
| SYNC (Pin 9) | External clock input | Replaces OPENLED on LT3755-1 variants; accepts 100kHz–1MHz logic-level sync signal with 50% duty cycle. |
| SS (Pin 10) | Soft-start timing | 10µA pull-up to 2.5V rail; soft-start time set by external capacitor; reset by UVLO or thermal fault. |
| RT (Pin 11) | Frequency programming | Resistor-to-GND sets oscillator frequency; 100kΩ yields ~375kHz; avoids need for internal oscillator trimming. |
| SHDN/UVLO (Pin 12) | Enable & undervoltage detect | 1.22V falling threshold with programmable hysteresis; sub-µA shutdown current when pulled ≤0.4V. |
| INTVCC (Pin 13) | Internal LDO output | 7.15V regulated supply for gate driver; requires 4.7µF local bypass; UVLO disables gate if <4.1V. |
| VIN (Pin 14) | Main input supply | 4.5V–40V input; must be bypassed with ≥0.22µF ceramic capacitor close to pin. |
| SENSE (Pin 15) | Low-side current sense | Kelvin-connected to FET source; monitors switch current for slope-compensated current-mode control. |
| GATE (Pin 16) | N-channel MOSFET driver | Drives external NFET gate between INTVCC and GND; fast rise/fall (<35ns) into 3300pF load. |
Key Features
| Feature | Design Value |
|---|---|
| SYNC pin for external clock synchronization | Enables deterministic phase alignment across multiple converters in multi-string LED systems, reducing EMI peak emissions. |
| High-side current sensing (ISP/ISN) | Supports all major topologies (boost/buck/buck-boost/SEPIC/flyback) without ground-referenced LED cathode constraints. |
| 100mV current sense threshold | Minimizes I²R losses in sense resistor while maintaining 1% current regulation accuracy over temperature. |
| 3000:1 true-color PWM dimming | Preserves LED color point across full dimming range via precise duty-cycle control without analog current modulation artifacts. |
| AEC-Q100 qualified (Grade E) | Validated for automotive ambient temperatures (–40°C to +125°C junction), including thermal cycling and HTOL stress testing. |
Applications
| Automotive LED Headlamps | Industrial High-Bay Lighting |
|---|---|
Use Scenario: Driving 50W white LED arrays in adaptive front-lighting systems (AFS) with dynamic beam shaping. IC Role / Device Role / Timing Role: Constant-current controller regulating LED string current up to 1.5A with 3000:1 PWM dimming for glare-free cornering light modulation. Use Value: AEC-Q100 qualification ensures reliability under automotive vibration, temperature cycling, and load-dump transients up to 40V. | Use Scenario: Powering 100–200W LED fixtures in warehouse ceilings with 0–10V or DALI-compatible analog dimming interfaces. IC Role / Device Role / Timing Role: High-efficiency buck-boost controller supporting universal 120/277VAC input via offline PFC front-end, delivering stable current despite line variations. Use Value: Adjustable 100kHz–1MHz frequency allows optimization for low-audio-noise operation in occupied spaces while minimizing magnetics size. |
| Architectural Signage Drivers | Medical Surgical Lighting |
Use Scenario: Controlling RGBW LED modules in dynamic façade lighting where color fidelity and flicker-free dimming are critical. IC Role / Device Role / Timing Role: Multi-topology controller enabling boost configuration for common-anode RGB strings, with independent CTRL-based analog dimming per channel. Use Value: 100mV high-side current sense threshold ensures <1% current matching across parallel LED strings for uniform chromaticity. | Use Scenario: Precision current regulation for high-CRI LED arrays in shadowless operating room lights requiring zero perceptible flicker. IC Role / Device Role / Timing Role: Constant-current source with 1.25V FB reference used for auxiliary voltage monitoring, enabling real-time LED health diagnostics via open-circuit detection. Use Value: OPENLED replacement by SYNC does not impact medical use - FB-based open-LED reporting remains fully functional with latch behavior confirmed in datasheet. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar LED controller applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LT3755EMSE#PBF | Lacks SYNC pin; includes OPENLED status output instead; identical pinout and package. | Better suited for systems requiring open-LED fault reporting without external clock sync. | Select when standalone fault signaling is prioritized over multi-converter synchronization. |
| LT3755EMSE-2#PBF | Includes improved OPENLED status pin with re-assertion behavior after overvoltage recovery; no SYNC. | Preferred for automotive rear lighting or DRL where robust fault latching and recovery are critical. | Choose for applications needing enhanced open-LED status persistence after transient overvoltage events. |
Compared with LT3755EMSE#PBF and LT3755EMSE-2#PBF, the LT3755EMSE-1#PBF trades open-LED reporting for deterministic clock synchronization-enabling lower EMI in multi-channel LED drivers but requiring external fault monitoring if OPENLED functionality is essential.
Availability
LT3755EMSE-1#PBF is available at Aetrix Electronics and suitable for automotive LED headlamps, industrial high-bay lighting, architectural signage, and medical surgical lighting requiring stable component supply, AEC-Q100 compliance, and precise high-current LED regulation.
Supply support for LT3755EMSE-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 precision instrumentation, industrial automation, communications, and automotive markets.
The LT3755 family is part of Analog Devices' Power by Linear™ portfolio, engineered specifically for high-reliability, high-efficiency LED driver applications demanding wide input range, topology flexibility, and automotive-grade robustness.
FAQ
What is the primary function of the SYNC pin on the LT3755EMSE-1#PBF?
The SYNC pin on the LT3755EMSE-1#PBF replaces the OPENLED function found on LT3755 and LT3755-2 variants and accepts an external logic-level clock signal (100kHz–1MHz, 50% duty cycle) to synchronize the internal oscillator. This enables deterministic phase alignment across multiple LT3755EMSE-1#PBF controllers in multi-string LED systems, reducing conducted and radiated EMI peaks. The RT resistor must be selected to set the internal frequency ~20% slower than the SYNC signal frequency for reliable locking.
How does the LT3755EMSE-1#PBF support both constant-current and constant-voltage regulation?
The LT3755EMSE-1#PBF supports dual regulation modes via separate feedback paths: LED current is regulated using high-side sensing across ISP and ISN pins, referenced to the CTRL pin voltage; output voltage is regulated via the FB pin, which targets 1.25V. When FB is active and within regulation, the controller maintains constant voltage; when ISP/ISN dominates, it enforces constant current. The two loops interact such that neither exceeds its threshold-enabling hybrid operation in applications like battery charging with current/voltage limits.
What is the significance of the 100mV current sense threshold in the LT3755EMSE-1#PBF?
The 100mV current sense threshold in the LT3755EMSE-1#PBF defines the nominal voltage difference between ISP and ISN required to trigger current-limit action. This low threshold minimizes power dissipation in the external sense resistor (e.g., 10mΩ at 10A yields only 0.1W), improving overall system efficiency and thermal design margin. It also enables high-accuracy current regulation (±3% over temperature) due to reduced sensitivity to PCB layout parasitics and resistor tolerance.
Can the LT3755EMSE-1#PBF be used in buck, boost, and buck-boost LED driver topologies?
Yes, the LT3755EMSE-1#PBF supports boost, buck, buck-boost, SEPIC, and flyback topologies due to its high-side current sensing architecture across ISP and ISN pins. Unlike controllers requiring low-side sensing, this configuration decouples LED cathode/anode grounding constraints-allowing the LED string to float relative to input and output grounds. This flexibility simplifies PCB layout and enables shared heat sinking in multi-topology designs without redesigning the current sense network.
What thermal considerations apply to the LT3755EMSE-1#PBF in automotive applications?
The LT3755EMSE-1#PBF is rated for –40°C to +125°C junction temperature (Grade E) and features an exposed pad (Pin 17) that must be soldered to a PCB ground plane for effective thermal conduction. With θJA = 43°C/W in MSOP package, sustained 1.5A LED current at 40V input requires ≥2 cm² copper area under the exposed pad and thermal vias to inner ground layers. Derating is recommended above 105°C ambient to maintain reliability over automotive lifetime requirements.
LT3755EMSE-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:
- 0°C ~ 125°C (TJ)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 16-MSOP-EP
LT3755EMSE-1#PBF FAQ
1.How can I place an order for LT3755EMSE-1#PBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LT3755EMSE-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 LT3755EMSE-1#PBF reliable?
The price and inventory of LT3755EMSE-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 LT3755EMSE-1#PBF is usually 5 days.
3.What payment methods are accepted for LT3755EMSE-1#PBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LT3755EMSE-1#PBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LT3755EMSE-1#PBF?
LT3755EMSE-1#PBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LT3755EMSE-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 LT3755EMSE-1#PBF?
For technical support, including LT3755EMSE-1#PBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LT3755EMSE-1#PBF requirements.
6.How does Aetrix verify that LT3755EMSE-1#PBF is sourced from the original manufacturer or authorized distributors?
All LT3755EMSE-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 LT3755EMSE-1#PBF meets industry standards.
7.What is the process for return or replacement of LT3755EMSE-1#PBF?
All LT3755EMSE-1#PBF units undergo pre-shipment inspection (PSI). If there is an issue with LT3755EMSE-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 LT3755EMSE-1#PBF part is unused and in its original packaging.
Return procedure for LT3755EMSE-1#PBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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