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Analog Devices Inc. LT3755EMSE#WPBF
- Part No.:
- LT3755EMSE#WPBF
- Manufacturer:
- Analog Devices Inc.
- Category:
- LED Drivers
- Package:
- 16-TFSOP (0.118", 3.00mm Width) Exposed Pad
- Datasheet:
-
LT3755EMSE#WPBF.pdf
- Description:
- IC LED DRIVER CTRLR PWM 16MSOP
- Quantity:
- Payment:
- Shipping:
Inventory:503
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Product details
Overview
LT3755EMSE#WPBF 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 LT3755EMSE#WPBF datasheet, LT3755EMSE#WPBF pinout, LT3755EMSE#WPBF application, or LT3755EMSE#WPBF equivalent, key selection criteria include high-side current sense architecture, programmable 100kHz–1MHz switching frequency, open LED protection via FB pin, adjustable analog dimming via CTRL pin, and thermally enhanced MSOP-16 packaging with exposed pad grounding.
Technical Context
The LT3755EMSE#WPBF implements fixed-frequency current-mode control with internal 7.15V INTVCC regulator powering gate driver and logic. Its ground-referenced FB pin enables dual-mode operation-constant-current regulation via ISP/ISN differential sensing (100mV threshold) and constant-voltage regulation at 1.25V nominal-while supporting fault detection including open LED (FB < VFB – 50mV) and overvoltage (FB > VFB + 60mV).
It integrates high-side current sense amplification with 95.5–103mV full-scale threshold (J-grade), CTRL-pin programmable current limit (0–1.1V range), and synchronized soft-start via SS pin with 10µA pull-up. The device uses an internal ramp generator and transconductance error amplifier (gm = 480µS) to stabilize loop dynamics across wide VIN and VOUT ranges.
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 single-string or multi-series white LED arrays for automotive headlamps and industrial lighting. |
| Current Sense Threshold | 100mV (typical) at ISP–ISN - sets LED current ILED = 100mV / RSENSE, enabling precise, low-loss sensing with standard resistors. |
| Switching Frequency Range | 100kHz to 1MHz - adjustable via RT resistor; higher frequencies reduce inductor size but increase switching loss. |
| Dimming Ratio | 3000:1 true-color PWM - preserves LED chromaticity across full brightness range without color shift. |
| Package & Thermal | 16-Lead MSOP with exposed pad - θJA = 43°C/W; requires soldered GND pad for thermal performance and noise immunity. |
| AEC-Q100 Grade | Grade E (–40°C to +125°C) - qualified for automotive front-lighting applications per stress test requirements. |
Pinout & Package
LT3755EMSE#WPBF 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 for thermal management and noise reduction. Pin numbering follows standard MSOP top-view orientation (Pin 1 at top-left corner, Pin 16 at bottom-right).
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| PWMOUT (Pin 1) | Buffered PWM output | Drives external NMOS disconnect switch; toggles low during FB overvoltage (> VFB + 60mV) to isolate LED load. |
| FB (Pin 2) | Voltage feedback input | Regulates to 1.25V nominal; enables CV mode and triggers OPENLED fault signal when below VFB – 50mV. |
| ISN (Pin 3) | Negative current sense input | High-side sense return; bias current ~25µA; enables short-circuit detection when ISN < 3V. |
| ISP (Pin 4) | Positive current sense input | High-side sense input; common-mode range 2.9V–75V; bias current varies with CTRL voltage. |
| VC (Pin 5) | Error amplifier output | Transconductance output (gm = 480µS); connects to RC compensation network for loop stability. |
| CTRL (Pin 6) | Current threshold adjust | Sets ISP–ISN threshold from 0V to 100mV linearly (0–1.1V), then clamps at full scale above 1.2V. |
| VREF (Pin 7) | 2.0V reference output | Stable 2.0V source (±2%); supplies bias for CTRL divider or temperature-compensation networks. |
| PWM (Pin 8) | Digital dimming input | Active-high enable; internal pull-down; controls oscillator, gate drive, and VC impedance state. |
| 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; 10kΩ → 1MHz, 100kΩ → 100kHz (typical). |
| SHDN/UVLO (Pin 11) | Enable & undervoltage detect | 1.22V falling threshold with programmable hysteresis; pulls 2.1µA below threshold to set hysteresis. |
| INTVCC (Pin 12) | Internal LDO output | 7.15V regulated supply (±3%) for gate driver and logic; requires 4.7µF ceramic bypass near pin. |
| VIN (Pin 13) | Main power input | 4.5V–40V input; must be bypassed with ≥0.22µF ceramic capacitor close to pin. |
| 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; rise/fall time <35ns (CL = 3300pF). |
| Exposed Pad (Pin 16) | Thermal & electrical GND | Must be soldered to PCB ground plane; serves as current sense return and thermal path (θJC = 4°C/W). |
Key Features
| Feature | Design Value |
|---|---|
| High-side current sensing | Enables flexible topology selection (boost/buck/buck-boost/SEPIC/flyback) without ground-loop interference. |
| Programmable 3000:1 PWM dimming | Maintains LED color fidelity across full intensity range using true-color modulation architecture. |
| Integrated 7.15V INTVCC LDO | Eliminates need for external bias supply; powers gate driver and logic while supporting VIN as low as 4.5V. |
| Open LED fault detection | Uses FB pin voltage drop (< VFB – 50mV) to assert OPENLED status signal-no extra comparator required. |
| Adjustable analog dimming via CTRL | Linearly scales current sense threshold from 0 to 100mV, enabling smooth analog brightness control. |
| AEC-Q100 qualified (Grade E) | Validated for automotive front-lighting use with guaranteed operation from –40°C to +125°C junction. |
Applications
| Automotive LED Headlamps | Battery-Powered LED Lighting |
|---|---|
Use Scenario: High-brightness adaptive front-lighting system (AFS) in passenger vehicles requiring dynamic beam shaping and daylight visibility. IC Role / Device Role / Timing Role: Constant-current LED controller managing 50W+ white LED strings in boost configuration with PWM dimming for DRL and low-beam modes. Use Value: AEC-Q100 qualification ensures reliability under automotive thermal cycling; 75V output supports long LED strings without cascading converters. | Use Scenario: Portable inspection light or emergency beacon powered by 12V sealed lead-acid or Li-ion battery packs. IC Role / Device Role / Timing Role: Efficient DC/DC controller operating in buck mode to regulate current for high-lumen LED arrays across varying battery voltage (10V–14.4V). Use Value: 4.5V minimum input enables operation down to deeply discharged batteries; <1µA shutdown current extends standby runtime. |
| Industrial Machine Vision Lighting | Architectural LED Drivers |
Use Scenario: Stroboscopic illumination for high-speed camera systems in automated optical inspection (AOI) equipment. IC Role / Device Role / Timing Role: Precision current source delivering microsecond-accurate LED pulses via synchronized PWM input and fast gate driver (35ns rise/fall). Use Value: 3000:1 dimming ratio enables fine-grained exposure control; high-side sensing avoids ground noise coupling into imaging sensors. | Use Scenario: Constant-current driver for RGBW LED modules in commercial façade lighting with DALI or 0–10V interface integration. IC Role / Device Role / Timing Role: Dual-loop controller using FB for voltage supervision and ISP/ISN for current regulation, supporting analog dimming via CTRL and digital dimming via PWM. Use Value: Ground-referenced FB pin simplifies interface with standard 0–10V dimmers; 16-pin MSOP footprint allows compact, cost-effective PCB layout. |
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 200kHz/600kHz dual-frequency option; no CTRL-based analog dimming; lower max VOUT (60V); no OPENLED pin. | Targeted at simpler boost-only LED drivers without high-side sensing flexibility or automotive qualification. | Select when fixed frequency and reduced feature set suffice; avoid for AEC-Q100 or multi-topology designs. |
| LM3410XSD/NOPB | Single-ended boost controller only; 32V max VOUT; integrated 1.5A FET; no high-side sensing; no AEC-Q100 rating. | Designed for low-power (<5W), space-constrained portable LED applications-not suitable for automotive or high-voltage strings. | Choose for cost-sensitive, low-complexity boost drivers where external FET control and 75V capability are unnecessary. |
Compared with LTC3783EFE#PBF and LM3410XSD/NOPB, the LT3755EMSE#WPBF uniquely combines AEC-Q100 qualification, 75V output, high-side current sensing for topology flexibility, and dual analog/PWM dimming-making it the only option qualified for demanding automotive headlamp systems requiring robust fault reporting and thermal resilience.
Availability
LT3755EMSE#WPBF 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-voltage LED string control.
Supply support for LT3755EMSE#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 is a global leader in high-performance analog, mixed-signal, and digital signal processing semiconductors, serving industrial, automotive, communications, and healthcare markets.
The LT3755 product line was designed specifically for high-efficiency, high-reliability LED current regulation in demanding environments-including automotive front lighting-where precision dimming, fault diagnostics, and wide input/output voltage range are critical.
FAQ
What is the primary function of the LT3755EMSE#WPBF in an LED driver circuit?
The LT3755EMSE#WPBF functions as a constant-current, fixed-frequency current-mode DC/DC controller that drives an external N-channel MOSFET to regulate LED current in boost, buck, buck-boost, SEPIC, or flyback configurations. It uses high-side current sensing (via ISP/ISN pins) and supports both PWM and analog (CTRL pin) dimming. In the LT3755EMSE#WPBF, this functionality is implemented with AEC-Q100 qualification, making it suitable for automotive headlamp applications where reliability and fault reporting are essential.
How does the LT3755EMSE#WPBF achieve open LED detection?
The LT3755EMSE#WPBF achieves open LED detection by monitoring the FB pin voltage: when FB falls below the internal 1.25V regulation threshold minus 50mV (i.e., <1.20V), the OPENLED pin asserts a pull-down signal indicating an open-circuit condition. This occurs because loss of LED current causes the FB node to drop due to lack of feedback current. The LT3755EMSE#WPBF implements this directly in hardware without external comparators, and the OPENLED status remains latched during PWM low periods for reliable fault reporting.
Can the LT3755EMSE#WPBF operate with input voltages below 5V?
No-the LT3755EMSE#WPBF has a specified minimum operating input voltage of 4.5V, and reliable startup requires VIN ≥ 4.5V with proper UVLO hysteresis setting. Below this, the internal INTVCC regulator cannot maintain 7.15V output, causing gate drive failure and control instability. While the SHDN/UVLO pin can be held low to achieve <1µA shutdown current, the LT3755EMSE#WPBF will not regulate or switch below 4.5V. For sub-4.5V operation, a different controller or pre-regulator stage is required.
What is the role of the CTRL pin on the LT3755EMSE#WPBF?
The CTRL pin on the LT3755EMSE#WPBF adjusts the ISP–ISN current sense threshold linearly from 0mV to 100mV as CTRL voltage increases from 0V to 1.1V; above 1.2V, the threshold clamps at 100mV. This enables analog dimming by scaling LED current without changing PWM duty cycle. The LT3755EMSE#WPBF uses this pin to provide smooth brightness control independent of switching frequency, and its 50nA input bias ensures minimal loading on external divider networks.
Is the LT3755EMSE#WPBF pin-compatible with other variants like LT3755-1 or LT3755-2?
No-the LT3755EMSE#WPBF corresponds to the base LT3755 variant and is not pin-compatible with LT3755-1 or LT3755-2. The LT3755-1 replaces the OPENLED pin (Pin 9) with SYNC for oscillator synchronization, while the LT3755-2 enhances OPENLED behavior with re-assertion logic after overvoltage events. Though all share the same MSOP-16 package and pinout numbering, functional pin assignments differ at Pin 9 (OPENLED vs SYNC), so direct substitution without schematic review is not supported.
LT3755EMSE#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#WPBF FAQ
1.How can I place an order for LT3755EMSE#WPBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LT3755EMSE#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#WPBF reliable?
The price and inventory of LT3755EMSE#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#WPBF is usually 5 days.
3.What payment methods are accepted for LT3755EMSE#WPBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LT3755EMSE#WPBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LT3755EMSE#WPBF?
LT3755EMSE#WPBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LT3755EMSE#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#WPBF?
For technical support, including LT3755EMSE#WPBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LT3755EMSE#WPBF requirements.
6.How does Aetrix verify that LT3755EMSE#WPBF is sourced from the original manufacturer or authorized distributors?
All LT3755EMSE#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#WPBF meets industry standards.
7.What is the process for return or replacement of LT3755EMSE#WPBF?
All LT3755EMSE#WPBF units undergo pre-shipment inspection (PSI). If there is an issue with LT3755EMSE#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#WPBF part is unused and in its original packaging.
Return procedure for LT3755EMSE#WPBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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