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Analog Devices Inc. LT3755EMSE-1#WPBF
- Part No.:
- LT3755EMSE-1#WPBF
- Manufacturer:
- Analog Devices Inc.
- Category:
- LED Drivers
- Package:
- 16-TFSOP (0.118", 3.00mm Width) Exposed Pad
- Datasheet:
-
LT3755EMSE-1#WPBF.pdf
- Description:
- IC LED DRIVER CTRLR PWM 16MSOP
- Quantity:
- Payment:
- Shipping:
Inventory:108
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Product details
Overview
LT3755EMSE-1#WPBF from Analog Devices is a constant-frequency, current-mode DC/DC LED controller optimized for automotive-grade high-power LED drivers. It drives an external N-channel MOSFET, supports 4.5V–40V input, delivers up to 75V output, enables 3000:1 PWM dimming, and operates in boost/buck/buck-boost topologies - exemplified in 50W white automotive headlamp designs.
For engineers reviewing the LT3755EMSE-1#WPBF datasheet, LT3755EMSE-1#WPBF pinout, LT3755EMSE-1#WPBF application, or LT3755EMSE-1#WPBF equivalent, key selection criteria include its AEC-Q100 qualification, high-side current sensing architecture, programmable 100kHz–1MHz switching frequency, open LED protection via OPENLED pin, and CTRL-based analog dimming capability.
Technical Context
The LT3755EMSE-1#WPBF implements a fixed-frequency current-mode control architecture with internal 7.15V INTVCC regulator powering the gate driver and logic. Its high-side current sense inputs (ISP/ISN) enable topology flexibility - including boost, buck, buck-boost, SEPIC, and flyback - while maintaining accurate constant-current regulation across wide VIN and VOUT ranges.
It features dual-loop regulation: the ISP–ISN differential voltage sets LED current (with 100mV nominal threshold), while FB provides constant-voltage feedback referenced to 1.25V. The LT3755-1 variant adds SYNC pin functionality for oscillator synchronization, distinguishing it from base LT3755 and LT3755-2 variants.
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 - sufficient for multi-string high-brightness LED arrays in headlamps. |
| Switching Frequency Range | 100kHz to 1MHz - adjustable via RT resistor to balance efficiency, EMI, and magnetics size. |
| Current Sense Threshold | 100mV (typical) at ISP–ISN - enables precise, low-loss high-side LED current sensing. |
| PWM Dimming Ratio | 3000:1 - meets stringent automotive lighting color stability requirements under pulse-width control. |
| Operating Temperature | –40°C to +125°C junction - qualified per AEC-Q100 Grade E for under-hood automotive use. |
| Package | 16-Lead Plastic MSOP - thermally enhanced with exposed pad soldered to PCB ground plane. |
Pinout & Package
LT3755EMSE-1#WPBF uses a 16-lead plastic MSOP package with exposed thermal pad (Pin 17 = GND). Pin numbering follows standard MSOP top-view orientation (Pin 1 at top-left corner, counterclockwise).
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| PWMOUT (Pin 1) | Buffered PWM output | Drives external NMOS disconnect switch; toggles low during FB overvoltage fault to isolate LED load. |
| FB (Pin 2) | Voltage feedback input | Regulates output voltage to 1.25V reference; enables open-LED detection when below 1.20V (typ). |
| ISN (Pin 3) | Negative current sense input | High-side current sense return; enables short-circuit detection if ISP–ISN > 150mV below 3V common mode. |
| ISP (Pin 4) | Positive current sense input | High-side current sense high terminal; bias current varies with CTRL voltage for dynamic range control. |
| VC (Pin 5) | Error amplifier output | Integrates error signal for loop stability; high-impedance during PWM low to retain state for next cycle. |
| CTRL (Pin 6) | Current threshold adjust | Sets ISP–ISN threshold from 0V to 100mV (linear 0–1V, constant >1.2V); enables analog dimming and temp compensation. |
| VREF (Pin 7) | 2.0V reference output | Stable 2.0V source (±2%) for CTRL divider or temperature-sensing circuits; supplies ≤100µA. |
| PWM (Pin 8) | Digital dimming input | Active-low enable; internally pulled down; controls oscillator, GATE, and VC clamping during idle. |
| SS (Pin 9) | Soft-start timing | 10µA pull-up to 2.5V rail; external capacitor sets startup ramp time and prevents inrush current. |
| RT (Pin 10) | Frequency programming | Resistor-to-GND sets oscillator frequency; 100kΩ yields ~375kHz per datasheet curve. |
| SHDN/UVLO (Pin 11) | Enable & undervoltage detect | 1.22V falling threshold with programmable hysteresis; <1µA shutdown IQ when pulled low. |
| INTVCC (Pin 12) | Internal LDO output | 7.15V regulated supply for gate driver; requires 4.7µF local ceramic bypass; UVLO at 4.1V protects FETs. |
| VIN (Pin 13) | Main power input | Bypassed locally with ≥0.22µF ceramic; powers INTVCC LDO and internal circuitry. |
| SENSE (Pin 14) | Low-side current sense | Kelvin-connected to source of external sense resistor; monitors switch current for slope-compensated current-mode control. |
| GATE (Pin 15) | MOSFET gate driver | Drives external N-channel FET between INTVCC and GND; rise/fall times <35ns into 3.3nF. |
| Exposed Pad (Pin 16) | Thermal & electrical ground | Must be soldered to PCB ground plane; improves thermal resistance (θJC = 4°C/W) and serves as current sense return path. |
Key Features
| Feature | Design Value |
|---|---|
| High-side current sensing | Enables flexible boost/buck/buck-boost/SEPIC/flyback topologies without ground-referenced LED strings. |
| SYNC pin (LT3755-1 only) | Allows external clock synchronization to reduce EMI and avoid beat frequencies in multi-controller systems. |
| Open LED protection | OPENLED pin asserts low when FB drops below 1.20V (typ), signaling open-circuit LED string failure. |
| Programmable soft-start | External capacitor on SS pin controls startup dI/dt, preventing inrush current and output overshoot. |
| AEC-Q100 Grade E qualification | Validated for automotive under-hood operation from –40°C to +125°C junction temperature. |
Applications
| Automotive LED Headlamps | Battery-Powered LED Lighting |
|---|---|
Use Scenario: High-intensity white LED array in adaptive front-lighting systems (AFS) requiring precise current regulation and thermal derating. IC Role / Device Role / Timing Role: Constant-current controller managing high-side sensed LED string current while synchronizing dimming with vehicle CAN bus commands. Use Value: 3000:1 PWM dimming preserves color fidelity; AEC-Q100 qualification ensures reliability in 125°C under-hood environments. | Use Scenario: Portable emergency lighting or inspection lamps powered by 12V sealed 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 IQ extends battery runtime. |
| Industrial Machine Vision Lighting | Architectural LED Signage |
Use Scenario: High-speed strobed LED arrays used in automated optical inspection (AOI) systems requiring microsecond-level dimming control. IC Role / Device Role / Timing Role: Fast-response current controller accepting TTL-level PWM signals to trigger precise LED pulses synchronized with camera exposure. Use Value: Sub-200ns propagation delay from PWM edge to GATE transition enables tight timing alignment with image capture. | Use Scenario: Outdoor LED signage with long strings requiring >60V compliance and robust open-circuit fault handling. IC Role / Device Role / Timing Role: Boost-mode constant-current driver supporting 20+ series LEDs with integrated open-LED status reporting. Use Value: OPENLED pin provides direct fault indication to MCU; 75V output capability eliminates need for cascaded stages. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar LED controller applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LTC3783EFE#PBF | Fixed 500kHz frequency; no SYNC pin; supports up to 60V output; lacks OPENLED pin. | Targeted at industrial DC-DC converters rather than automotive LED drivers; no AEC-Q100 qualification. | Choose for cost-sensitive non-automotive boost/buck applications where SYNC and open-LED reporting are unnecessary. |
| LM3410XSDX/NOPB | Integrated 1.5A MOSFET; 3MHz switching; max 32V output; no high-side sensing or SYNC. | Designed for low-power single-LED portable lighting; not suitable for multi-string or automotive headlamp loads. | Choose only for compact, low-current (<350mA) LED drivers where integration outweighs flexibility and ruggedness. |
Compared with LTC3783EFE#PBF and LM3410XSDX/NOPB, LT3755EMSE-1#WPBF uniquely combines AEC-Q100 qualification, high-side current sensing, SYNC capability, and 75V output - making it the only option qualified for demanding automotive headlamp systems requiring both safety-critical fault reporting and topology flexibility.
Availability
LT3755EMSE-1#WPBF is available at Aetrix Electronics and suitable for automotive LED headlamps, industrial machine vision lighting, and outdoor architectural signage requiring stable component supply, AEC-Q100 compliance, and high-voltage LED string control.
Supply support for LT3755EMSE-1#WPBF 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, designed specifically for high-efficiency, high-reliability LED driver applications in automotive and industrial environments where precision current regulation and fault resilience are critical.
FAQ
What distinguishes LT3755EMSE-1#WPBF from the base LT3755 and LT3755-2 variants?
The LT3755EMSE-1#WPBF incorporates the SYNC pin function (replacing OPENLED on Pin 3), enabling external clock synchronization to reduce EMI in multi-converter systems. Unlike LT3755 (OPENLED only) and LT3755-2 (enhanced OPENLED latching), LT3755EMSE-1#WPBF prioritizes timing coordination over open-LED status reporting - confirmed by pin function tables and block diagram labeling in Rev. E datasheet.
Does LT3755EMSE-1#WPBF support constant-voltage regulation in addition to constant-current mode?
Yes, LT3755EMSE-1#WPBF supports dual-loop regulation: constant-current via ISP/ISN differential sensing and constant-voltage via FB pin referenced to 1.25V. When FB is actively used, the controller regulates output voltage; when ISP/ISN dominates, it regulates LED current - with interaction managed by internal error amplifiers as described in the OPERATION section.
What is the purpose of the CTRL pin on LT3755EMSE-1#WPBF, and how does it affect LED current accuracy?
The CTRL pin on LT3755EMSE-1#WPBF adjusts the ISP–ISN current sense threshold from 0mV to 100mV linearly (0–1V) then holds constant (>1.2V), enabling analog dimming and temperature compensation. This allows precise scaling of LED current without changing sense resistor value - directly improving accuracy across temperature and line variations per Electrical Characteristics table (CTRL input bias current <100nA, VREF = 2.00V ±2%).
How is thermal performance managed in the MSOP package of LT3755EMSE-1#WPBF?
LT3755EMSE-1#WPBF's 16-lead MSOP package includes an exposed thermal pad (Pin 17) that must be soldered to the PCB ground plane. This achieves θJC = 4°C/W, enabling reliable operation at 125°C junction temperature. Datasheet specifies TJMAX = 125°C for E-grade, with thermal shutdown active above this limit - verified in Absolute Maximum Ratings and Thermal Characteristics sections.
Can LT3755EMSE-1#WPBF drive LED strings in buck configuration with input voltage higher than output voltage?
Yes, LT3755EMSE-1#WPBF supports buck-mode operation when configured with high-side current sensing and appropriate external components. Its architecture allows buck, boost, buck-boost, SEPIC, and flyback topologies - explicitly stated in FEATURES and APPLICATIONS sections. Input voltage can exceed output voltage (e.g., 24V VIN driving 12V LED string) without violating operating constraints.
LT3755EMSE-1#WPBF 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:
- General Purpose
- Operating Temperature:
- -40°C ~ 125°C (TJ)
- Grade:
- Automotive
- Qualification:
- AEC-Q100
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 16-MSOP-EP
LT3755EMSE-1#WPBF FAQ
1.How can I place an order for LT3755EMSE-1#WPBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LT3755EMSE-1#WPBF 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#WPBF reliable?
The price and inventory of LT3755EMSE-1#WPBF 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#WPBF is usually 5 days.
3.What payment methods are accepted for LT3755EMSE-1#WPBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LT3755EMSE-1#WPBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LT3755EMSE-1#WPBF?
LT3755EMSE-1#WPBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LT3755EMSE-1#WPBF 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#WPBF?
For technical support, including LT3755EMSE-1#WPBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LT3755EMSE-1#WPBF requirements.
6.How does Aetrix verify that LT3755EMSE-1#WPBF is sourced from the original manufacturer or authorized distributors?
All LT3755EMSE-1#WPBF 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#WPBF meets industry standards.
7.What is the process for return or replacement of LT3755EMSE-1#WPBF?
All LT3755EMSE-1#WPBF units undergo pre-shipment inspection (PSI). If there is an issue with LT3755EMSE-1#WPBF, 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#WPBF part is unused and in its original packaging.
Return procedure for LT3755EMSE-1#WPBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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