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Analog Devices Inc. LT3755EMSE#WTRPBF
- Part No.:
- LT3755EMSE#WTRPBF
- Manufacturer:
- Analog Devices Inc.
- Category:
- LED Drivers
- Package:
- 16-TFSOP (0.118", 3.00mm Width) Exposed Pad
- Datasheet:
-
LT3755EMSE#WTRPBF.pdf
- Description:
- IC LED DRIVER CTRLR PWM 16MSOP
- Quantity:
- Payment:
- Shipping:
Inventory:3,799
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Product details
Overview
LT3755EMSE#WTRPBF 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 with 4.5V–40V input, 100mV high-side current sense threshold, and 3000:1 PWM dimming for automotive LED headlamps.
For engineers reviewing the LT3755EMSE#WTRPBF datasheet, LT3755EMSE#WTRPBF pinout, LT3755EMSE#WTRPBF application, or LT3755EMSE#WTRPBF equivalent, key selection criteria include high-side current sensing capability, AEC-Q100 qualification, open LED protection via FB-based fault detection, and programmable 100kHz–1MHz switching frequency for EMI and magnetics optimization.
Technical Context
The LT3755EMSE#WTRPBF implements fixed-frequency current-mode control with internal 7.15V INTVCC regulator powering gate driver and logic. Its transconductance error amplifier (VC) stabilizes either LED current (via ISP/ISN differential sensing) or output voltage (via FB reference at 1.25V), enabling dual regulation modes in a single IC.
It features dedicated high-side current sense inputs (ISP/ISN) supporting common-mode voltages up to 75V, integrated short-circuit protection triggering at >150mV differential when ISN < 3V, and programmable undervoltage lockout on SHDN/UVLO with 20mV hysteresis - all confirmed for the E-grade MSOP variant.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 4.5V to 40V - supports wide automotive battery range including cold-crank and load-dump conditions. |
| Output Voltage Capability | Up to 75V - enables driving long LED strings in headlamp and signage applications. |
| Current Sense Threshold | 100mV (typical) at ISP–ISN - enables precise, low-loss high-side current sensing with minimal resistor power dissipation. |
| Switching Frequency Range | 100kHz to 1MHz - adjustable via RT pin resistor to balance efficiency, EMI, and external component size. |
| Dimming Ratio | 3000:1 true-color PWM dimming - preserves LED chromaticity across full brightness range for automotive lighting compliance. |
| Operating Temperature | –40°C to +125°C junction - qualified per AEC-Q100 Grade E for under-hood automotive use. |
| Package | 16-lead MSOP - thermally enhanced surface-mount package with exposed pad soldered to PCB ground for thermal management. |
Pinout & Package
LT3755EMSE#WTRPBF is housed in a 16-lead plastic MSOP package (3mm × 4.9mm) with exposed thermal pad (Pin 17) that must be soldered to PCB ground. 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 (>VFB + 60mV) to isolate LED load and prevent damage. |
| FB (Pin 2) | Voltage feedback input | Ground-referenced node regulating output voltage at 1.25V; also triggers OPENLED pull-down when below VFB – 50mV (open LED detection). |
| 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 input; accepts up to 75V common-mode voltage for flexible topology placement. |
| VC (Pin 5) | Error amplifier output | High-impedance compensation node storing demand state during PWM off-time; requires RC network for loop stability. |
| CTRL (Pin 6) | Current threshold adjust | Sets ISP–ISN regulation point: linear scaling (0–1V) then constant 100mV above 1.2V - enables analog dimming and temperature compensation. |
| VREF (Pin 7) | 2.0V reference output | Stable 2.0V source (±2%) supplying ≤100µA; used to bias CTRL divider for analog dimming or thermal foldback. |
| PWM (Pin 8) | Digital dimming input | Active-low enable: disables switching, idles oscillator, and places VC in high-Z storage mode; internal pull-down. |
| SS (Pin 9) | Soft-start control | 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 (100kHz–1MHz); no internal pull-up - must not float. |
| SHDN/UVLO (Pin 11) | Shutdown & UVLO input | 1.22V falling threshold with programmable hysteresis; pulls 2.1µA below threshold to set hysteresis with external divider. |
| INTVCC (Pin 12) | Internal LDO output | 7.15V regulated supply (±150mV) for gate driver and logic; requires 4.7µF ceramic bypass close to pin. |
| VIN (Pin 13) | Main input supply | Accepts 4.5V–40V; powers INTVCC LDO and internal circuitry; requires local 0.22µF+ ceramic bypass. |
| SENSE (Pin 14) | Low-side current sense | Kelvin-connected to FET source; monitors switch current for slope-compensated current-mode control. |
| GATE (Pin 15) | NMOS gate driver | Drives external FET gate between INTVCC and GND; clamped low during shutdown/fault/idle. |
| Exposed Pad (Pin 16) | Thermal & signal ground | Must be soldered to PCB ground plane; serves as primary thermal path and current sense return for SENSE. |
Key Features
| Feature | Design Value |
|---|---|
| High-side current sensing | Supports ISP/ISN common-mode up to 75V - enables optimal placement in boost/buck-boost topologies without level-shifting. |
| AEC-Q100 Grade E qualification | Validated for automotive under-hood operation from –40°C to +125°C junction - meets reliability requirements for headlamp drivers. |
| True-color PWM dimming | 3000:1 ratio with minimal color shift - achieved via precise timing control and fast gate drive (35ns rise/fall) preserving LED spectral integrity. |
| Open LED fault detection | FB-based status signaling (OPENLED pin) asserts when FB drops below VFB – 50mV - provides fail-safe indication without additional circuitry. |
| Programmable soft-start | RC-controlled ramp on SS pin prevents inrush current and output overshoot during startup - critical for high-power LED systems. |
| Integrated short-circuit protection | Automatic GATE disable when ISP–ISN > 150mV at ISN < 3V - protects FET and magnetics during output short events. |
Applications
| Automotive LED Headlamps | Battery-Powered LED 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 while supporting PWM dimming synchronized to vehicle CAN bus commands. Use Value: AEC-Q100 qualification ensures reliability in high-temperature engine bay environments; 75V output supports multi-string configurations without cascading converters. |
Use Scenario: Portable medical device illumination requiring flicker-free, low-noise light output from 12V sealed lead-acid battery. IC Role / Device Role / Timing Role: Buck-mode LED driver maintaining stable current despite battery voltage sag from 12.8V to 9.5V during discharge. Use Value: Wide 4.5V–40V input range accommodates deep discharge; 100mV current sense minimizes power loss in current-sense resistor. |
| Industrial High-Bay Lighting | Architectural LED Signage |
|
Use Scenario: 150W high-bay fixture using series-connected LEDs powered from 24VDC industrial bus. IC Role / Device Role / Timing Role: Boost-mode controller delivering regulated 60V output with analog dimming via 0–10V control interface. Use Value: CTRL pin enables smooth 0–100% analog dimming; high-side sensing simplifies layout by eliminating ground-referenced shunt placement constraints. |
Use Scenario: Outdoor RGB pixel sign with independent channel control requiring precise current matching across red/green/blue LEDs. IC Role / Device Role / Timing Role: Constant-current source per channel with identical 100mV sense threshold ensuring consistent luminance and color point. Use Value: Matched ISP/ISN threshold tolerance (±10mV) minimizes inter-channel current variation; 3000:1 PWM enables fine-grained brightness control. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar LED controller applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LT3756EMSE#WTRPBF | Higher 100V output capability; improved ISP/ISN common-mode range (up to 100V); same pinout and feature set. | Required for LED strings exceeding 75V or operating in higher-voltage industrial systems. | Select when output voltage > 75V is needed; drop-in replacement otherwise. |
| LM3410XSDX/NOPB | Single-stage buck-only controller; lower 36V max output; no high-side sensing; no OPENLED or SYNC functionality. | Limited to low-voltage LED arrays (<36V) where topology flexibility and fault reporting are not required. | Choose only for cost-sensitive, low-complexity buck applications with VIN < 24V and fixed output voltage. |
Compared with LT3755EMSE#WTRPBF, LT3756EMSE#WTRPBF extends voltage headroom for future-proofing high-string-count designs, while LM3410XSDX/NOPB sacrifices topology versatility and protection features for lower BOM cost in constrained buck-only use cases.
Availability
LT3755EMSE#WTRPBF is available at Aetrix Electronics and suitable for automotive LED headlamps, industrial high-bay lighting, portable medical illumination, and architectural signage requiring stable component supply with AEC-Q100 assurance.
Supply support for LT3755EMSE#WTRPBF 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 automotive, industrial, communications, and healthcare markets.
The LT3755 product line was designed specifically for high-reliability, high-efficiency LED current regulation in demanding automotive and industrial lighting applications - emphasizing robust fault protection, wide input/output ranges, and AEC-Q100 compliance.
FAQ
What topology configurations does the LT3755EMSE#WTRPBF support?
The LT3755EMSE#WTRPBF supports boost, buck, buck-boost, SEPIC, and flyback topologies due to its high-side current sensing architecture and ground-referenced FB pin. This flexibility allows designers to select the optimal configuration based on input/output voltage relationship and efficiency targets - for example, buck mode for 24V input to 12V LED string, or boost for 12V input to 48V string. The LT3755EMSE#WTRPBF datasheet confirms all five topologies in the Applications section.
How does the LT3755EMSE#WTRPBF implement open LED detection?
The LT3755EMSE#WTRPBF uses the FB pin voltage to detect open LED conditions: when FB falls below VFB – 50mV (typically 1.20V), the OPENLED pin asserts a pull-down signal. This occurs because open-circuit conditions cause the feedback divider to collapse, reducing FB voltage. The LT3755EMSE#WTRPBF integrates this function directly - no external comparators or timers are needed. The OPENLED status remains latched during PWM low periods and updates on next PWM high transition.
Can the LT3755EMSE#WTRPBF operate with input voltage below 6V?
Yes, the LT3755EMSE#WTRPBF operates down to 4.5V input, but SHDN/UVLO pin voltage must not exceed VIN when VIN < 6V to ensure proper undervoltage lockout behavior. For sub-6V operation, tie SHDN/UVLO directly to VIN or use a resistor divider referenced to VIN. The LT3755EMSE#WTRPBF's internal INTVCC LDO maintains 7.15V regulation even at 4.5V input, enabling gate drive functionality throughout the specified range.
What is the role of the CTRL pin on the LT3755EMSE#WTRPBF?
The CTRL pin on the LT3755EMSE#WTRPBF adjusts the ISP–ISN current sense threshold: from 0V to 1V, it scales linearly (e.g., 0.5V → 50mV threshold); above 1.2V, it holds constant at 100mV. This enables analog dimming, thermal foldback (by connecting NTC to VREF–CTRL divider), or current derating. The LT3755EMSE#WTRPBF specifies CTRL input bias current ≤100nA, minimizing divider loading errors.
Is the LT3755EMSE#WTRPBF pin-compatible with other variants like LT3755-1 or LT3755-2?
No - LT3755EMSE#WTRPBF is the base variant without SYNC or enhanced OPENLED features. LT3755-1 replaces OPENLED with SYNC on Pin 3; LT3755-2 adds improved OPENLED latching behavior. While all share identical MSOP pinout and core functionality, Pin 3 function differs: LT3755EMSE#WTRPBF uses it as OPENLED, whereas LT3755EMSE-1#WTRPBF uses it as SYNC. Interchange requires schematic and firmware review.
LT3755EMSE#WTRPBF 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:
- 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#WTRPBF FAQ
1.How can I place an order for LT3755EMSE#WTRPBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LT3755EMSE#WTRPBF 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#WTRPBF reliable?
The price and inventory of LT3755EMSE#WTRPBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LT3755EMSE#WTRPBF is usually 5 days.
3.What payment methods are accepted for LT3755EMSE#WTRPBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LT3755EMSE#WTRPBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LT3755EMSE#WTRPBF?
LT3755EMSE#WTRPBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LT3755EMSE#WTRPBF 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#WTRPBF?
For technical support, including LT3755EMSE#WTRPBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LT3755EMSE#WTRPBF requirements.
6.How does Aetrix verify that LT3755EMSE#WTRPBF is sourced from the original manufacturer or authorized distributors?
All LT3755EMSE#WTRPBF 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#WTRPBF meets industry standards.
7.What is the process for return or replacement of LT3755EMSE#WTRPBF?
All LT3755EMSE#WTRPBF units undergo pre-shipment inspection (PSI). If there is an issue with LT3755EMSE#WTRPBF, 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#WTRPBF part is unused and in its original packaging.
Return procedure for LT3755EMSE#WTRPBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
LT3755EMSE#WTRPBF Tags
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