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Analog Devices Inc. LT3755EMSE#PBF
- Part No.:
- LT3755EMSE#PBF
- Manufacturer:
- Analog Devices Inc.
- Category:
- LED Drivers
- Package:
- 16-TFSOP (0.118", 3.00mm Width) Exposed Pad
- Datasheet:
-
LT3755EMSE#PBF.pdf
- Description:
- IC LED DRIVER CTRLR PWM 16MSOP
- Quantity:
- Payment:
- Shipping:
Inventory:385
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Product details
Overview
LT3755EMSE#PBF 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 supports 4.5V–40V input, delivers up to 75V output, senses high-side LED current with 100mV threshold, and enables 3000:1 PWM dimming - used in automotive headlamp drivers and industrial LED lighting systems.
For engineers reviewing the LT3755EMSE#PBF datasheet, LT3755EMSE#PBF pinout, LT3755EMSE#PBF application, or LT3755EMSE#PBF equivalent, key selection considerations include high-side current sensing architecture, programmable 100kHz–1MHz switching frequency, open-LED protection via FB pin, AEC-Q100 qualification (E-grade), and MSOP-16 thermal performance with exposed pad grounding.
Technical Context
The LT3755EMSE#PBF 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 sense or output voltage via FB pin, supporting dual-loop operation with priority arbitration.
High-side current sensing enables topology flexibility and avoids ground loop interference; the CTRL pin adjusts current threshold from 100mV (full-scale) down to ~0mV via analog dimming; OPENLED status (LT3755 variant) asserts when FB falls 50mV below 1.25V reference, indicating open-circuit LED fault.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 4.5V to 40V - supports wide-range battery and industrial supplies without pre-regulation. |
| Output Voltage Capability | Up to 75V - enables multi-LED string operation in automotive and signage applications. |
| Current Sense Threshold | 100mV (typical) at ISP–ISN - sets precise LED current with low power loss in sense resistor. |
| Switching Frequency Range | 100kHz to 1MHz (RT-programmable) - balances efficiency, EMI, and magnetic component size. |
| Dimming Ratio | 3000:1 true-color PWM - preserves color consistency across full brightness range in display/lighting. |
| Operating Junction Temp | –40°C to +125°C - qualified for under-hood automotive and industrial ambient conditions. |
| Package Thermal Resistance | θJA = 43°C/W (MSOP) - requires minimal PCB copper area for thermal management. |
Pinout & Package
LT3755EMSE#PBF uses a thermally enhanced 16-lead plastic MSOP package with exposed pad (Pin 17) soldered to PCB ground plane for thermal and electrical integrity. Pin numbering follows standard MSOP top-view orientation (Pin 1 at top-left corner).
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| PWMOUT (Pin 1) | Buffered PWM output | Drives NMOS disconnect switch or level-shifts PWM signal; toggles low during FB overvoltage fault. |
| FB (Pin 2) | Voltage feedback input | Regulates output voltage to 1.25V reference; triggers OPENLED pull-down if <1.20V (open-LED detection). |
| ISN (Pin 3) | Negative current sense input | High-side LED current sense return; enables short-circuit detection when ISN <3V. |
| ISP (Pin 4) | Positive current sense input | High-side LED current sense high terminal; bias current varies with CTRL voltage. |
| VC (Pin 5) | Error amplifier output | Integrates regulation error; high-impedance during PWM low to retain state for next cycle. |
| CTRL (Pin 6) | Analog dimming control | Sets ISP–ISN threshold from 0mV to 100mV linearly (0–1V), then clamps at full scale (>1.2V). |
| VREF (Pin 7) | 2.0V reference output | Stable 2.0V source for CTRL divider or temperature compensation networks; drives ≤100µA. |
| PWM (Pin 8) | Digital dimming input | Active-high enable; disables oscillator and forces GATE/PWMOUT low when low. |
| OPENLED (Pin 9) | Open-LED status output | Open-collector pull-down asserted when FB <1.20V - signals LED string disconnection. |
| SS (Pin 10) | Soft-start timing | 10µA internal current charges external capacitor; resets on UVLO or thermal fault. |
| RT (Pin 11) | Frequency programming | Resistor-to-GND sets oscillator frequency; 100kΩ → ~375kHz per datasheet curve. |
| SHDN/UVLO (Pin 12) | Shutdown & input monitoring | 1.22V falling threshold with programmable hysteresis; pulls 2.1µA to set UVLO window. |
| INTVCC (Pin 13) | Internal LDO output | 7.15V regulated supply for gate driver; requires 4.7µF local ceramic bypass. |
| VIN (Pin 14) | Main power input | Bypassed with ≥0.22µF ceramic; powers INTVCC LDO and internal circuitry. |
| SENSE (Pin 15) | Low-side switch current sense | Kelvin-connected to FET source; compares against 108mV current limit threshold. |
| GATE (Pin 16) | NMOS gate driver | Swings between GND and INTVCC; drives external power FET with 35ns rise/fall times. |
| Exposed Pad (Pin 17) | Thermal & electrical ground | Mandatory solder connection to PCB ground plane for thermal dissipation and noise control. |
Key Features
| Feature | Design Value |
|---|---|
| High-side current sensing | Enables flexible topology selection (boost/buck/buck-boost/SEPIC/flyback) without compromising ground reference. |
| Programmable 100kHz–1MHz frequency | Optimizes magnetics size, efficiency, and EMI filtering for each application's thermal and layout constraints. |
| 3000:1 true-color PWM dimming | Maintains consistent LED chromaticity across full brightness range - critical for automotive and display lighting. |
| Open-LED fault detection | Uses FB pin voltage drop (≤1.20V) to assert OPENLED pull-down - enables system-level fault reporting and safety shutdown. |
| AEC-Q100 qualified (Grade E) | Validated for automotive under-hood environments including temperature cycling, vibration, and ESD robustness. |
| 100mV high-side current sense threshold | Minimizes I²R losses in sense resistor while maintaining precision regulation across temperature and load. |
Applications
| Automotive LED Headlamps | Industrial High-Bay Lighting |
|---|---|
|
Use Scenario: 50W white LED headlamp module operating from 8V–40V vehicle battery with cold-crank tolerance. IC Role / Device Role / Timing Role: Constant-current LED controller regulating 1.5A string current while managing boost converter dynamics and thermal foldback. Use Value: AEC-Q100 qualification ensures reliability in under-hood environments; 3000:1 PWM dimming enables adaptive driving beam control without color shift. |
Use Scenario: 100W high-bay fixture using multiple parallel LED strings powered from 24V DC distribution bus. IC Role / Device Role / Timing Role: High-side current-sense controller enabling buck-mode operation with single-point current regulation across strings. Use Value: 100mV sense threshold reduces heat generation in current shunt; MSOP package allows compact driver board integration in space-constrained fixtures. |
| UV-C Disinfection Systems | Stage & Architectural Lighting |
|
Use Scenario: Pulsed UV-C LED array (275nm) requiring precise current control and fast on/off transitions for germicidal duty cycles. IC Role / Device Role / Timing Role: Fast-response current-mode controller synchronizing LED current pulses with external timing signals via PWM input. Use Value: 35ns gate drive rise/fall times support microsecond-level current switching; open-LED detection prevents overvoltage stress during lamp failure. |
Use Scenario: RGBW tunable architectural fixture where independent current control of each color channel is required. IC Role / Device Role / Timing Role: Four-channel controller (one per channel) using CTRL pin for analog dimming and PWM for high-ratio digital dimming. Use Value: Dual dimming interface (PWM + CTRL) enables seamless 20-bit effective resolution; 1.25V FB reference supports constant-voltage auxiliary circuits. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar LED controller applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LTC3783EMSE#PBF | Higher VIN max (60V), integrated gate driver bootstrap diode, no OPENLED pin, 500kHz fixed frequency. | Preferred for higher-input industrial supplies; lacks open-LED status reporting and adjustable frequency. | Select when input exceeds 40V or bootstrap diode integration simplifies layout; not suitable for automotive open-fault diagnostics. |
| LM3410XMF/NOPB | Single-stage buck-only controller, 40V VIN, 1.25V FB reference, no high-side sensing, 1.5A integrated switch. | Targeted at low-power (<15W), cost-sensitive buck LED drivers without topology flexibility. | Choose for simple, low-component-count buck designs below 15W; cannot replace LT3755EMSE#PBF in boost or high-power applications. |
Compared with LTC3783EMSE#PBF and LM3410XMF/NOPB, the LT3755EMSE#PBF uniquely combines AEC-Q100 qualification, programmable frequency, high-side sensing, and open-LED reporting in a single MSOP package - making it optimal for automotive and high-reliability multi-topology LED systems.
Availability
LT3755EMSE#PBF is available at Aetrix Electronics and suitable for automotive LED headlamps, industrial high-bay lighting, UV-C disinfection systems, and stage lighting requiring stable component supply, long-term lifecycle support, and AEC-Q100 compliance.
Supply support for LT3755EMSE#PBF 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 Linear Technology) is a global leader in high-performance analog, mixed-signal, and power management ICs.
The LT3755 product line was designed specifically for high-efficiency, high-reliability LED current regulation across automotive, industrial, and medical lighting applications - emphasizing topology flexibility, fault resilience, and thermal robustness.
FAQ
What is the maximum output voltage supported by the LT3755EMSE#PBF?
The LT3755EMSE#PBF supports output voltages up to 75V, enabling direct drive of long LED strings in automotive and industrial lighting. This rating applies regardless of topology (boost, buck-boost, SEPIC, or flyback) and is limited only by external component voltage ratings and layout parasitics - not by internal circuitry.
Does the LT3755EMSE#PBF support both constant-current and constant-voltage regulation?
Yes, the LT3755EMSE#PBF supports dual regulation modes: constant-current via ISP/ISN differential sensing and constant-voltage via the FB pin referenced to 1.25V. The two loops interact - the current loop dominates unless FB drops below its threshold, at which point open-LED protection activates. Both modes are simultaneously active and prioritized internally.
What is the function of the OPENLED pin on the LT3755EMSE#PBF?
The OPENLED pin on the LT3755EMSE#PBF is an open-collector output that pulls low when the FB voltage falls below 1.20V (i.e., 50mV below the 1.25V regulation threshold), signaling an open LED string condition. It requires an external pull-up resistor (<1mA) and is latched during PWM low periods - providing reliable fault indication without continuous polling.
Can the LT3755EMSE#PBF be used in buck configuration?
Yes, the LT3755EMSE#PBF supports buck topology through high-side current sensing - unlike traditional buck controllers that rely on low-side sensing. This allows the LED string to remain grounded while regulating current, simplifying thermal management and EMI design. External components (inductor, diode, MOSFET) must be selected for buck operation per the datasheet design equations.
What is the purpose of the CTRL pin on the LT3755EMSE#PBF?
The CTRL pin on the LT3755EMSE#PBF adjusts the ISP–ISN current sense threshold from 0mV to 100mV, enabling analog dimming. For 0V < VCTRL < 1V, threshold = 0.1 × VCTRL; above 1.2V, it clamps at 100mV. This provides fine-grained current control independent of PWM, supporting smooth dimming transitions and temperature compensation networks.
LT3755EMSE#PBF 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:
- -
- Operating Temperature:
- 0°C ~ 125°C (TJ)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 16-MSOP-EP
LT3755EMSE#PBF FAQ
1.How can I place an order for LT3755EMSE#PBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LT3755EMSE#PBF 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#PBF reliable?
The price and inventory of LT3755EMSE#PBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LT3755EMSE#PBF is usually 5 days.
3.What payment methods are accepted for LT3755EMSE#PBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LT3755EMSE#PBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LT3755EMSE#PBF?
LT3755EMSE#PBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LT3755EMSE#PBF 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#PBF?
For technical support, including LT3755EMSE#PBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LT3755EMSE#PBF requirements.
6.How does Aetrix verify that LT3755EMSE#PBF is sourced from the original manufacturer or authorized distributors?
All LT3755EMSE#PBF 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#PBF meets industry standards.
7.What is the process for return or replacement of LT3755EMSE#PBF?
All LT3755EMSE#PBF units undergo pre-shipment inspection (PSI). If there is an issue with LT3755EMSE#PBF, 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#PBF part is unused and in its original packaging.
Return procedure for LT3755EMSE#PBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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