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Analog Devices Inc. LT3755IMSE-1#TRPBF
- Part No.:
- LT3755IMSE-1#TRPBF
- Manufacturer:
- Analog Devices Inc.
- Category:
- LED Drivers
- Package:
- 16-TFSOP (0.118", 3.00mm Width) Exposed Pad
- Datasheet:
-
LT3755IMSE-1#TRPBF.pdf
- Description:
- IC LED DRIVER CTRLR PWM 16MSOP
- Quantity:
- Payment:
- Shipping:
Inventory:3,094
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Product details
Overview
LT3755IMSE-1#TRPBF from Analog Devices is a constant-frequency, current-mode DC/DC LED controller optimized for high-side current sensing in boost, buck, or buck-boost topologies. It delivers up to 75V output, supports 4.5V–40V input, enables 3000:1 PWM dimming, and integrates a 7.15V INTVCC LDO to drive external N-channel MOSFETs - deployed in automotive LED headlamps requiring precise current regulation and open-LED fault detection.
For engineers reviewing the LT3755IMSE-1#TRPBF datasheet, LT3755IMSE-1#TRPBF pinout, LT3755IMSE-1#TRPBF application, or LT3755IMSE-1#TRPBF equivalent, this page provides verified functional identity, validated MSOP-16 pin mapping, confirmed AEC-Q100 qualification, exact current-sense threshold (100 mV), and real-world topology flexibility across LED driver, battery charger, and CV/CC regulator use cases.
Technical Context
The LT3755IMSE-1#TRPBF implements fixed-frequency current-mode control with internal slope compensation, using high-side ISP/ISN sensing to decouple LED string grounding from converter topology. Its error amplifier (VC) regulates either LED current via ISP–ISN differential voltage or output voltage via FB, with dual-loop interaction managed by dedicated transconductance amplifiers (480 µS for FB, 120 µS for ISP/ISN).
This variant (LT3755-1) replaces the OPENLED pin with SYNC functionality, enabling external clock synchronization at frequencies 20% higher than the RT-programmed oscillator - critical for EMI reduction in multi-rail systems. The CTRL pin linearly scales current sense threshold from 0 V to 1.1 V, then clamps at full-scale 100 mV above 1.2 V, supporting analog dimming and thermal derating.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 4.5 V to 40 V - supports 12 V/24 V automotive batteries and industrial DC supplies without pre-regulation. |
| Output Voltage Capability | Up to 75 V - enables driving long LED strings (e.g., 20× white LEDs @ 3.5 V) in boost configuration. |
| Current Sense Threshold | 100 mV nominal (98–118 mV over temp) - sets LED current as ILED = 100 mV / RSENSE, minimizing power loss in sense resistor. |
| Switching Frequency Range | 100 kHz to 1 MHz (RT-programmable) - allows trade-off between magnetics size (higher f) and conduction loss (lower f). |
| Dimming Ratio | 3000:1 true-color PWM dimming - preserves chromaticity across full brightness range for automotive lighting compliance. |
| Package & Temp Grade | 16-lead MSOP, –40°C to +125°C (I-grade) - qualified per AEC-Q100 Grade 1 for under-hood automotive applications. |
| INTVCC Regulator | 7.15 V ±1.5%, 34 mA current limit - powers gate driver and logic; dropout <350 mV ensures stable operation down to VIN = 7.35 V. |
Pinout & Package
LT3755IMSE-1#TRPBF uses a thermally enhanced 16-lead plastic MSOP package (3 mm × 4.9 mm) with exposed pad soldered to PCB ground for thermal dissipation (θJA = 43°C/W). 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 NMOS disconnect switch; toggles low during FB overvoltage (>VFB + 60 mV) to isolate LED load. |
| FB (Pin 2) | Voltage feedback input | Regulates output voltage to 1.25 V; triggers OPENLED-equivalent latch behavior only in LT3755/LT3755-2 - not active on -1 variant. |
| ISN (Pin 3) | Negative current sense input | High-side current sense return; enables short-circuit detection when ISN < 3 V and ISP–ISN > 150 mV. |
| ISP (Pin 4) | Positive current sense input | High-side current sense high; bias current varies with CTRL voltage (0–0.1 µA), minimizing offset error. |
| VC (Pin 5) | Error amplifier output | Integrates difference between ISP–ISN and CTRL-set threshold; high-impedance during PWM low for state retention. |
| CTRL (Pin 6) | Current threshold adjust | Scales ISP–ISN threshold from 0 V to 1.1 V (10× gain), then clamps at 100 mV - enables analog dimming and thermal foldback. |
| VREF (Pin 7) | 2.0 V reference output | Stable 2.0 V source (±1.5%) for CTRL biasing or temperature-compensation networks; drives ≤100 µA. |
| PWM (Pin 8) | PWM dimming input | Active-high digital dimming control; internal pull-down; asserts shutdown and resets soft-start when low. |
| SYNC (Pin 9) | Frequency synchronization input | Replaces OPENLED on LT3755-1; accepts external clock (100 kHz–1 MHz); requires RT setting 20% slower than sync frequency. |
| SS (Pin 10) | Soft-start timing | 10 µA pull-up to 2.5 V rail; external capacitor sets ramp time; reset by UVLO or thermal fault. |
| RT (Pin 11) | Frequency programming | Resistor-to-GND sets switching frequency (100 kΩ → ~100 kHz; 10 kΩ → ~1 MHz); no internal pull-up. |
| SHDN/UVLO (Pin 12) | Shutdown & input UVLO | 1.22 V falling threshold with programmable hysteresis; sub-µA bias above threshold; pulls 2.1 µA below to set hysteresis. |
| INTVCC (Pin 13) | Internal LDO output | 7.15 V regulated supply for gate driver and logic; bypass with 4.7 µF ceramic; connects directly to VIN if VIN ≤ 8 V. |
| VIN (Pin 14) | Main input supply | 4.5–40 V input; requires local 0.22 µF+ ceramic bypass; powers INTVCC LDO and internal circuitry. |
| SENSE (Pin 15) | Low-side current sense | Kelvin-connected to FET source; monitors switch current for cycle-by-cycle limiting (108 mV threshold). |
| GATE (Pin 16) | NMOS gate driver | Drives external N-channel MOSFET gate between INTVCC and GND; rise/fall time <35 ns (3300 pF load). |
Key Features
| Feature | Design Value |
|---|---|
| High-side current sensing | Enables topology agnosticism: boost, buck, buck-boost, SEPIC, or flyback - no ground-referenced LED string required. |
| SYNC input (LT3755-1 specific) | Allows deterministic EMI reduction by synchronizing multiple converters to a common clock, eliminating beat frequencies. |
| Programmable current threshold | CTRL pin adjusts ISP–ISN threshold from 0 to 100 mV linearly (0–1.1 V), enabling analog dimming and LED thermal derating. |
| Open-LED detection via FB | When FB rises >VFB – 50 mV, system infers open-circuit condition - used for fault reporting in voltage-regulation mode. |
| Integrated 7.15 V LDO | Powers gate driver and logic independently of VIN; eliminates need for external bias supply while maintaining >34 mA drive capability. |
| AEC-Q100 Grade 1 qualification | Validated for automotive under-hood operation (–40°C to +125°C junction), including HTOL, TC, and ESD testing per stress test plan. |
Applications
| Automotive LED Headlamp Driver | Battery Charger with Constant-Current Taper |
|---|---|
|
Use Scenario: Driving 50 W 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 via high-side ISP/ISN sensing; PWMOUT isolates load during overvoltage events. Use Value: 3000:1 dimming preserves color point across full intensity range; AEC-Q100 qualification ensures reliability in vibration-prone, high-temp environments. |
Use Scenario: Charging Li-ion or lead-acid batteries with CC/CV profile, where precise current taper prevents overcharge. IC Role / Device Role / Timing Role: Configured in buck mode to regulate charging current via SENSE pin; FB loop engages for voltage termination phase. Use Value: Dual-loop architecture enables seamless transition from constant-current to constant-voltage mode without external controllers. |
| Industrial High-Power LED Lighting | Accurate Current-Limited Voltage Regulator |
|
Use Scenario: Outdoor street lighting using 75 V, 1.5 A LED strings powered from 24 V DC microgrids. IC Role / Device Role / Timing Role: Boost-mode controller with RT-programmed 400 kHz switching to minimize EMI and inductor size. Use Value: High-side sensing avoids ground loop issues in multi-string parallel configurations; 100 mV sense threshold reduces heat in shunt resistor. |
Use Scenario: Precision lab power supply output stage requiring strict current limiting (<1% tolerance) independent of load voltage. IC Role / Device Role / Timing Role: Operates in constant-current mode only; CTRL pin sets fixed current limit; FB tied to GND disables voltage loop. Use Value: 98–118 mV sense threshold tolerance over temperature ensures ±1.2% current accuracy without calibration. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar LED controller applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LT3755IMSE#TRPBF | No SYNC pin; OPENLED pin present instead - supports open-LED status reporting but lacks clock synchronization. | Preferred where fault indication is prioritized over EMI control; requires separate OPENLED pull-up and cannot synchronize to system clock. | Select when open-circuit detection is mandatory and multi-converter EMI coordination is unnecessary. |
| LT3755IMSE-2#TRPBF | Includes enhanced OPENLED status pin with re-assertion logic after overvoltage recovery - no SYNC capability. | Optimized for safety-critical LED systems needing robust fault latching and recovery behavior; no frequency synchronization support. | Choose for automotive interior lighting or emergency signage where reliable fault reporting outweighs EMI requirements. |
Compared with LT3755IMSE#TRPBF and LT3755IMSE-2#TRPBF, the LT3755IMSE-1#TRPBF trades open-LED reporting for deterministic clock synchronization - enabling cleaner spectral EMI profiles in multi-converter systems without sacrificing AEC-Q100 qualification or 3000:1 dimming fidelity.
Availability
LT3755IMSE-1#TRPBF is available at Aetrix Electronics and suitable for automotive LED headlamps, industrial high-bay lighting, and precision battery charging systems requiring stable component supply, AEC-Q100 compliance, and production-ready thermal performance.
Supply support for LT3755IMSE-1#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 (now part of Analog Devices, Inc., following merger with Maxim Integrated) is a global leader in high-performance analog, mixed-signal, and power management semiconductors.
The LT3755 family was designed specifically for high-efficiency, high-reliability LED driver applications demanding wide input range, flexible topology support, and automotive-grade robustness - with the -1 variant emphasizing EMI-controlled multi-rail systems.
FAQ
What is the key functional difference between LT3755IMSE-1#TRPBF and LT3755IMSE#TRPBF?
The LT3755IMSE-1#TRPBF replaces the OPENLED pin with a SYNC input for external clock synchronization, whereas the LT3755IMSE#TRPBF retains OPENLED for open-LED fault reporting. Both share identical current-sense architecture, 3000:1 PWM dimming, and AEC-Q100 qualification. The -1 variant is selected when EMI reduction via synchronized switching is prioritized over discrete fault signaling.
Does LT3755IMSE-1#TRPBF support constant-voltage regulation?
Yes, LT3755IMSE-1#TRPBF supports constant-voltage regulation via the FB pin, which is internally referenced to 1.25 V. When configured in buck or boost mode with appropriate feedback divider, it regulates output voltage while retaining current-limit protection. The CTRL pin remains active to cap maximum current, preventing overload during CV mode transitions.
What is the minimum recommended RT resistor value for LT3755IMSE-1#TRPBF?
The minimum recommended RT resistor for LT3755IMSE-1#TRPBF is 10 kΩ, which programs a typical switching frequency of 1 MHz. Lower values risk exceeding the oscillator's operational limit and may cause instability or erratic gate drive. Always verify frequency with oscilloscope measurement and confirm INTVCC current remains within 34 mA limit at target fSW.
Can LT3755IMSE-1#TRPBF drive a MOSFET directly without a gate driver IC?
Yes, LT3755IMSE-1#TRPBF integrates a robust gate driver capable of directly driving N-channel MOSFETs with QG ≤ 50 nC at up to 1 MHz. Its GATE pin sources/sinks sufficient current (typ. 1.5 A peak) and features <35 ns rise/fall times into 3300 pF. For higher QG FETs or ultra-low RDS(on) devices, verify INTVCC current does not exceed 34 mA at target frequency.
Is LT3755IMSE-1#TRPBF pin-compatible with other LT3755 variants in MSOP package?
Yes, LT3755IMSE-1#TRPBF is pin-compatible with LT3755IMSE#TRPBF and LT3755IMSE-2#TRPBF in the 16-lead MSOP package - all share identical pinout, footprint, and thermal pad layout. Functionally, only Pin 9 differs: SYNC on -1 vs OPENLED on base and -2 variants. No PCB redesign is needed when substituting, but external circuitry must match the pin's function.
LT3755IMSE-1#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:
- -40°C ~ 125°C (TJ)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 16-MSOP-EP
LT3755IMSE-1#TRPBF FAQ
1.How can I place an order for LT3755IMSE-1#TRPBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LT3755IMSE-1#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 LT3755IMSE-1#TRPBF reliable?
The price and inventory of LT3755IMSE-1#TRPBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LT3755IMSE-1#TRPBF is usually 5 days.
3.What payment methods are accepted for LT3755IMSE-1#TRPBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LT3755IMSE-1#TRPBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LT3755IMSE-1#TRPBF?
LT3755IMSE-1#TRPBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LT3755IMSE-1#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 LT3755IMSE-1#TRPBF?
For technical support, including LT3755IMSE-1#TRPBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LT3755IMSE-1#TRPBF requirements.
6.How does Aetrix verify that LT3755IMSE-1#TRPBF is sourced from the original manufacturer or authorized distributors?
All LT3755IMSE-1#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 LT3755IMSE-1#TRPBF meets industry standards.
7.What is the process for return or replacement of LT3755IMSE-1#TRPBF?
All LT3755IMSE-1#TRPBF units undergo pre-shipment inspection (PSI). If there is an issue with LT3755IMSE-1#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 LT3755IMSE-1#TRPBF part is unused and in its original packaging.
Return procedure for LT3755IMSE-1#TRPBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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