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Analog Devices Inc. LT3755EMSE#TRPBF
- Part No.:
- LT3755EMSE#TRPBF
- Manufacturer:
- Analog Devices Inc.
- Category:
- LED Drivers
- Package:
- 16-TFSOP (0.118", 3.00mm Width) Exposed Pad
- Datasheet:
-
LT3755EMSE#TRPBF.pdf
- Description:
- IC LED DRIVER CTRLR PWM 16MSOP
- Quantity:
- Payment:
- Shipping:
Inventory:9,762
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Product details
Overview
LT3755EMSE#TRPBF 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 features 4.5V–40V input range, 75V output capability, 100mV high-side current sense threshold, 3000:1 PWM dimming, and AEC-Q100 qualification for automotive headlamp drivers.
For engineers reviewing the LT3755EMSE#TRPBF datasheet, LT3755EMSE#TRPBF pinout, LT3755EMSE#TRPBF application, or LT3755EMSE#TRPBF equivalent, key selection considerations include high-side current sensing architecture, programmable 100kHz–1MHz switching frequency, open LED protection via FB-based fault detection, and thermally enhanced MSOP-16 packaging with exposed pad grounding.
Technical Context
The LT3755EMSE#TRPBF implements fixed-frequency current-mode control with internal 7.15V INTVCC regulator powering gate driver and logic. Its error amplifier (VC) regulates either LED current via ISP/ISN differential sensing or output voltage via FB pin - dual-loop operation enables seamless transition between constant-current and constant-voltage modes.
High-side current sensing supports flexible topology deployment without ground-referenced LED strings. The CTRL pin adjusts current threshold from 0 to 100mV (10× scaling), while PWM input enables true-color dimming; OPENLED status pin (active-low open-drain) asserts when FB falls below VFB – 50mV, signaling open-circuit LED faults.
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 high-brightness automotive lighting. |
| Current Sense Threshold | 100mV (typical) at ISP–ISN - enables precise, low-loss high-side current sensing with minimal power dissipation. |
| Switching Frequency Range | 100kHz to 1MHz - adjustable via RT resistor to optimize efficiency, EMI, or magnetic component size. |
| PWM Dimming Ratio | 3000:1 - delivers flicker-free, high-fidelity color stability across full brightness range. |
| Operating Junction Temp | –40°C to +125°C - qualified per AEC-Q100 Grade E for under-hood automotive environments. |
| Package Type | 16-Lead Plastic MSOP with exposed thermal pad - provides enhanced thermal performance in space-constrained PCB layouts. |
Pinout & Package
LT3755EMSE#TRPBF 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 convention (Pin 1 = VREF, Pin 16 = GATE).
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| VREF (Pin 1) | 2.0V reference output | Provides stable bias for CTRL pin divider; supplies ≤100µA for analog dimming or temperature compensation networks. |
| PWM (Pin 2) | Digital dimming enable | Active-high input controlling oscillator and gate drive; internal pull-down allows idle-state shutdown with <1µA quiescent current. |
| OPENLED (Pin 3) | Open LED fault indicator | Open-drain output asserting low when FB < VFB – 50mV; requires external pull-up <1mA for status reporting. |
| SS (Pin 4) | Soft-start timing control | 10µA internal current source charges external capacitor to ramp VC and prevent inrush current during startup. |
| FB (Pin 5) | Voltage feedback input | Ground-referenced node regulating output voltage to 1.25V; also enables open-LED detection and overvoltage protection. |
| PWMOUT (Pin 6) | Buffered PWM signal | INTVCC-referenced output mirroring PWM state; drives NMOS disconnect switch or level-shifts for high-side FET control. |
| GATE (Pin 7) | NMOS gate driver | Drives external low-side N-channel MOSFET between INTVCC and GND; fast 35ns rise/fall times support high-frequency operation. |
| SENSE (Pin 8) | Low-side current sense | Kelvin-connected to source of power MOSFET; monitors switch current for slope-compensated current-mode control. |
| CTRL (Pin 9) | Analog dimming control | Sets ISP–ISN current threshold from 0 to 100mV (10× scaling); enables smooth analog dimming or thermal derating. |
| VC (Pin 10) | Error amplifier output | High-impedance transconductance output stabilizing both current and voltage loops; requires RC compensation network. |
| ISP (Pin 11) | High-side current sense (+) | Connects to positive terminal of LED string current-sense resistor; common-mode range up to 75V supports high-voltage outputs. |
| ISN (Pin 12) | High-side current sense (–) | Connects to negative terminal of current-sense resistor; enables accurate high-side sensing without ground disruption. |
| RT (Pin 13) | Frequency programming | Resistor-to-GND sets oscillator frequency from 100kHz–1MHz; enables EMI optimization and magnetics sizing. |
| SHDN/UVLO (Pin 14) | Enable & undervoltage lockout | 1.22V falling threshold with programmable hysteresis; disables IC and resets soft-start during brownout events. |
| INTVCC (Pin 15) | Internal LDO supply | 7.15V regulated output powering gate driver and logic; bypassed with 4.7µF ceramic capacitor near pin. |
| VIN (Pin 16) | Main input supply | Accepts 4.5V–40V; locally bypassed with ≥0.22µF ceramic capacitor to suppress high-frequency noise. |
Key Features
| Feature | Design Value |
|---|---|
| High-side current sensing | Enables topology flexibility (boost/buck/buck-boost/SEPIC/flyback) without compromising LED string grounding or requiring shunt resistors on ground path. |
| True Color PWM™ dimming | 3000:1 ratio preserves LED chromaticity across entire dimming range - critical for automotive adaptive front-lighting systems (AFS). |
| Programmable open LED protection | FB-based fault detection triggers OPENLED assertion at VFB – 50mV, enabling fail-safe shutdown before overvoltage damage occurs. |
| Adjustable frequency with RT pin | 100kHz–1MHz range allows trade-off between efficiency (lower fSW), EMI filtering cost (higher fSW), and magnetics size (higher fSW → smaller inductors). |
| AEC-Q100 Grade E qualification | Validated for automotive use across –40°C to +125°C junction temperature - meets reliability requirements for headlamp and daytime running light (DRL) applications. |
Applications
| Automotive LED Headlamps | Battery-Powered LED Lighting |
|---|---|
|
Use Scenario: High-power white LED arrays in adaptive front-lighting systems (AFS) requiring precise current regulation and rapid dimming response. IC Role / Device Role / Timing Role: Constant-current controller managing boost converter driving 50W+ LED strings; synchronizes PWM dimming with vehicle CAN bus commands. Use Value: 3000:1 True Color PWM dimming maintains CCT stability; high-side sensing avoids ground loop interference in chassis-grounded lamp housings. |
Use Scenario: Portable medical devices or handheld inspection tools using high-brightness LEDs powered by Li-ion batteries (3.0–4.2V nominal). IC Role / Device Role / Timing Role: Buck-boost LED driver maintaining constant current despite battery voltage sag; supports analog dimming via CTRL pin for user interface control. Use Value: Wide 4.5–40V input range accommodates battery packs up to 10S; 100mV current sense minimizes power loss in compact, thermally constrained enclosures. |
| Industrial Machine Vision Lighting | Architectural LED Signage |
|
Use Scenario: Stroboscopic LED arrays in factory automation cameras requiring microsecond-level flash timing and consistent luminance across batches. IC Role / Device Role / Timing Role: Precision current source with fast transient response; PWM input synchronized to camera trigger signals for repeatable exposure control. Use Value: Current-mode architecture ensures stable duty-cycle control independent of input/output variations; OPENLED fault flag enables predictive maintenance alerts. |
Use Scenario: Outdoor RGB LED signage operating in variable ambient temperatures with strict lifetime and color consistency requirements. IC Role / Device Role / Timing Role: Constant-current driver for individual red/green/blue channels; uses CTRL pin for thermal derating to extend LED lifespan at elevated ambient temperatures. Use Value: VREF output powers precision resistor dividers for channel-matched analog dimming; AEC-Q100 qualification ensures long-term reliability in uncontrolled outdoor environments. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar LED controller applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LT3756EMSE#TRPBF | Higher 60V ISP/ISN common-mode range (vs 75V), identical pinout and feature set; adds spread-spectrum modulation for EMI reduction. | Preferred for ultra-low EMI designs where CISPR-25 Class 5 compliance is required; otherwise functionally interchangeable. | Select LT3756EMSE#TRPBF if EMI certification is critical; otherwise LT3755EMSE#TRPBF offers same performance at lower cost. |
| LM3410XSDX/NOPB | Single-stage buck-only controller; 2.7–24V input; no high-side sensing; 1.25V FB reference only; no OPENLED or CTRL analog dimming. | Limited to low-voltage, single-string LED applications; lacks fault reporting and multi-topology flexibility. | Choose LM3410XSDX/NOPB only for cost-sensitive, low-power (<10W), fixed-buck designs where diagnostic features are unnecessary. |
Compared with LT3756EMSE#TRPBF, the LT3755EMSE#TRPBF omits spread-spectrum operation but retains identical topology support and fault protection - making it optimal for cost-driven automotive lighting where EMI is managed externally. Versus LM3410XSDX/NOPB, LT3755EMSE#TRPBF delivers full high-voltage, multi-topology, and diagnostic capability essential for industrial and premium automotive use.
Availability
LT3755EMSE#TRPBF is available at Aetrix Electronics and suitable for automotive LED headlamps, battery-powered portable lighting, industrial machine vision systems, and architectural signage requiring stable component supply, AEC-Q100 compliance, and high-reliability thermal performance.
Supply support for LT3755EMSE#TRPBF 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 with precision power management solutions.
The LT3755 product line was designed specifically for high-efficiency, high-reliability LED current regulation in demanding automotive and industrial lighting applications - emphasizing topology flexibility, fault resilience, and AEC-Q100 qualification.
FAQ
What topology configurations does the LT3755EMSE#TRPBF support?
The LT3755EMSE#TRPBF supports boost, buck, buck-boost, SEPIC, and flyback topologies due to its high-side current sensing architecture and ground-referenced FB pin. This eliminates ground-path disruption in LED strings and enables flexible layout in space-constrained automotive and industrial lighting modules. Each configuration requires appropriate external passive components and MOSFET selection aligned with voltage/current requirements.
How does the LT3755EMSE#TRPBF implement open LED protection?
The LT3755EMSE#TRPBF implements open LED protection by monitoring the FB pin voltage: when FB falls below VFB – 50mV (typical), the OPENLED pin asserts low to signal an open-circuit condition. This occurs because the voltage feedback loop becomes active when LED current drops to zero, pulling FB toward the 1.25V reference. The LT3755EMSE#TRPBF uses this behavior to provide fail-safe status reporting without additional sensors.
Can the LT3755EMSE#TRPBF operate in constant-voltage mode?
Yes, the LT3755EMSE#TRPBF operates in constant-voltage mode by connecting the FB pin to the output voltage divider - the internal transconductance amplifier regulates FB to 1.25V (nominal). In this mode, the ISP/ISN current sense loop remains active but is subordinated; the device maintains output voltage stability while retaining overvoltage protection via PWMOUT deactivation if FB exceeds VFB + 60mV.
What is the purpose of the CTRL pin on the LT3755EMSE#TRPBF?
The CTRL pin on the LT3755EMSE#TRPBF adjusts the ISP–ISN current sense threshold from 0 to 100mV (10× scaling), enabling analog dimming or thermal derating. For VCTRL ≤ 1V, ILED = (VCTRL – 100mV)/(10 • RLED); above 1.2V, threshold is fixed at 100mV. This allows precise current control independent of PWM, supporting hybrid dimming schemes and temperature-compensated LED drive in the LT3755EMSE#TRPBF.
Is the LT3755EMSE#TRPBF pin-compatible with other variants like LT3755-1 or LT3755-2?
No, the LT3755EMSE#TRPBF is not pin-compatible with LT3755-1 or LT3755-2 variants: LT3755-1 replaces OPENLED with SYNC for oscillator synchronization, while LT3755-2 enhances OPENLED latching behavior. All share identical MSOP-16 pinout and core functionality, but pin 3 function differs - LT3755EMSE#TRPBF uses OPENLED, whereas LT3755EMSE-1#TRPBF uses SYNC and LT3755EMSE-2#TRPBF uses improved OPENLED logic.
LT3755EMSE#TRPBF 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:
- -
- Operating Temperature:
- 0°C ~ 125°C (TJ)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 16-MSOP-EP
LT3755EMSE#TRPBF FAQ
1.How can I place an order for LT3755EMSE#TRPBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LT3755EMSE#TRPBF 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#TRPBF reliable?
The price and inventory of LT3755EMSE#TRPBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LT3755EMSE#TRPBF is usually 5 days.
3.What payment methods are accepted for LT3755EMSE#TRPBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LT3755EMSE#TRPBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LT3755EMSE#TRPBF?
LT3755EMSE#TRPBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LT3755EMSE#TRPBF 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#TRPBF?
For technical support, including LT3755EMSE#TRPBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LT3755EMSE#TRPBF requirements.
6.How does Aetrix verify that LT3755EMSE#TRPBF is sourced from the original manufacturer or authorized distributors?
All LT3755EMSE#TRPBF 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#TRPBF meets industry standards.
7.What is the process for return or replacement of LT3755EMSE#TRPBF?
All LT3755EMSE#TRPBF units undergo pre-shipment inspection (PSI). If there is an issue with LT3755EMSE#TRPBF, 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#TRPBF part is unused and in its original packaging.
Return procedure for LT3755EMSE#TRPBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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