My Inquiry
My Account
Analog Devices Inc. LT3755IUD-1#PBF
- Part No.:
- LT3755IUD-1#PBF
- Manufacturer:
- Analog Devices Inc.
- Category:
- LED Drivers
- Package:
- 16-WFQFN Exposed Pad
- Datasheet:
-
LT3755IUD-1#PBF.pdf
- Description:
- IC LED DRIVER CTRLR PWM 16QFN
- Quantity:
- Payment:
- Shipping:
Inventory:1,776
Please send an inquiry. Send us your inquiry, and we will respond immediately.
Product details
Overview
LT3755IUD-1#PBF from Analog Devices is a constant-frequency, current-mode DC/DC LED controller driving external N-channel MOSFETs in boost, buck, or buck-boost topologies. It features 4.5V–40V input range, 75V output capability, 100kHz–1MHz adjustable switching frequency, high-side current sensing with 100mV threshold, and AEC-Q100 qualification for automotive headlamp drivers.
For engineers reviewing the LT3755IUD-1#PBF datasheet, LT3755IUD-1#PBF pinout, LT3755IUD-1#PBF application, or LT3755IUD-1#PBF equivalent, key selection considerations include its frequency synchronization capability (LT3755-1 variant), open LED protection logic, PWM/CTRL dual dimming interface, and thermally enhanced 3mm × 3mm QFN package with exposed pad.
Technical Context
The LT3755IUD-1#PBF implements fixed-frequency current-mode control with internal 7.15V INTVCC regulator powering gate driver and logic. Its oscillator supports external RT resistor programming and synchronization via dedicated SYNC pin-exclusive to the -1 variant-enabling precise timing alignment with system clocks.
High-side current sensing across ISP/ISN enables flexible topology support without ground loop interference; the FB pin provides constant-voltage regulation or open-LED fault detection at 1.25V reference, while CTRL pin adjusts current sense threshold from 0V to 100mV linearly below 1V and holds full-scale above 1.2V.
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 |
| Switching Frequency Range | 100kHz to 1MHz - adjustable via RT pin; SYNC pin allows external clock locking for EMI reduction |
| Current Sense Threshold | 100mV nominal at ISP–ISN - enables accurate high-side LED current regulation with low power loss |
| Dimming Ratio | 3000:1 true-color PWM - preserves color consistency across full brightness range in automotive lighting |
| Operating Temperature | –40°C to +125°C junction - qualified per AEC-Q100 Grade I for under-hood automotive use |
| Package | 16-lead 3mm × 3mm QFN with exposed thermal pad - provides low θJA = 68°C/W for high-power LED driver thermal management |
Pinout & Package
LT3755IUD-1#PBF uses a thermally enhanced 16-lead (3mm × 3mm) plastic QFN package with exposed pad (Pin 17) soldered to PCB ground for thermal and electrical integrity.
| 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 |
| FB (Pin 2) | Voltage feedback input | Regulates to 1.25V; enables CV mode and open-LED detection (pulls OPENLED when FB < VFB – 50mV) |
| ISN (Pin 3) | Negative current sense input | High-side current sense return; short-circuit detection active below 3V common-mode voltage |
| ISP (Pin 4) | Positive current sense input | High-side current sense high terminal; bias current varies with CTRL voltage |
| VC (Pin 5) | Error amplifier output | Integrates ISP–ISN error; high-impedance during PWM low to retain state for next cycle |
| CTRL (Pin 6) | Current threshold adjust | Sets ISP–ISN threshold from 0V to 100mV linearly (0–1V), then holds full scale (>1.2V) |
| VREF (Pin 7) | 2.0V reference output | Stable 2.0V source for CTRL divider or temperature compensation networks; supplies ≤100µA |
| PWM (Pin 8) | Digital dimming input | Active-low shutdown; disables oscillator, pulls GATE/PWMOUT low, and places VC in high-Z hold |
| SYNC (Pin 9) | Frequency sync input | Replaces OPENLED on -1 variant; accepts external clock to lock oscillator phase and reduce EMI |
| SS (Pin 10) | Soft-start control | 10µA pull-up to 2.5V rail; external capacitor sets ramp time; reset by UVLO or thermal fault |
| RT (Pin 11) | Frequency set resistor | Connects to GND; selects switching frequency from 100kHz (100kΩ) to 1MHz (10kΩ) |
| SHDN/UVLO (Pin 12) | Shutdown & undervoltage detect | 1.22V falling threshold with programmable hysteresis; sub-µA bias in shutdown |
| INTVCC (Pin 13) | Internal LDO output | 7.15V regulated supply for gate driver and logic; requires 4.7µF local ceramic bypass |
| VIN (Pin 14) | Main input supply | 4.5V–40V input; must be bypassed with ≥0.22µF ceramic capacitor near pin |
| SENSE (Pin 15) | Low-side current sense | Kelvin-connected to FET source; monitors switch current for slope-compensated current-mode control |
| GATE (Pin 16) | NMOS gate driver | Drives external FET gate between INTVCC and GND; clamped during fault or shutdown |
| Exposed Pad (Pin 17) | Thermal & electrical ground | Mandatory solder connection to PCB ground plane for thermal dissipation and noise immunity |
Key Features
| Feature | Design Value |
|---|---|
| Frequency synchronization | SYNC pin enables deterministic phase alignment with system clocks, reducing conducted EMI peaks |
| True-color PWM dimming | 3000:1 ratio preserves chromaticity across full intensity range-critical for automotive adaptive driving beams |
| High-side current sensing | ISP/ISN inputs eliminate ground path interference, enabling flexible boost/buck/buck-boost/SEPIC/flyback configurations |
| Open LED fault reporting | OPENLED pin (replaced by SYNC on -1) asserts open-circuit condition via FB voltage drop below VFB – 50mV |
| AEC-Q100 Grade I qualification | Validated for –40°C to +125°C operation with automotive-grade reliability testing and traceable lot control |
Applications
| Automotive LED Headlamps | Battery-Powered LED Lighting |
|---|---|
Use Scenario: High-brightness adaptive front-lighting systems (AFS) requiring precise current regulation and fast PWM dimming for dynamic beam shaping. IC Role / Device Role / Timing Role: Constant-current LED controller managing boost converter stage with synchronized switching and open-LED fault signaling. Use Value: Enables 3000:1 true-color dimming and AEC-Q100 compliance for safety-critical illumination without color shift. | Use Scenario: Portable medical devices or handheld instruments using high-efficiency white LED arrays powered by Li-ion batteries. IC Role / Device Role / Timing Role: Wide-input buck-boost LED driver maintaining stable current across 3.0–4.2V battery discharge curve. Use Value: Delivers consistent lumen output and thermal stability using high-side sensing and programmable soft-start. |
| Industrial LED Signage | UV-C LED Disinfection Systems |
Use Scenario: Outdoor digital billboards operating in variable ambient temperatures with high-reliability LED string management. IC Role / Device Role / Timing Role: Constant-current controller in SEPIC topology supporting 12–24V input and 40–60V LED string output. Use Value: Provides open-LED detection and thermal foldback to prevent catastrophic failure in unattended installations. | Use Scenario: Pulsed UV-C LED arrays for surface disinfection requiring precise current pulses and rapid turn-on/turn-off. IC Role / Device Role / Timing Role: Fast-response current controller using PWM input to deliver microsecond-scale current pulses with minimal overshoot. Use Value: Achieves >99% germicidal efficacy through accurate peak current control and jitter-free dimming timing. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar LED controller applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LT3755IUD#PBF | Lacks SYNC pin; OPENLED function retained; identical pinout and electrical specs except sync capability | Suitable where EMI-sensitive synchronous operation is not required; retains open-LED status reporting | Select when system clock synchronization is unnecessary and fault indication is prioritized |
| LT3755IUD-2#PBF | Includes improved OPENLED status pin with re-assertion logic after overvoltage recovery; no SYNC pin | Better suited for safety-critical applications requiring robust open-LED detection after transient overvoltage events | Select when enhanced fault reporting reliability outweighs need for frequency synchronization |
Compared with LT3755IUD#PBF and LT3755IUD-2#PBF, the LT3755IUD-1#PBF uniquely enables deterministic EMI reduction via external clock locking while sacrificing open-LED reporting-making it optimal for tightly synchronized automotive lighting clusters where timing precision supersedes standalone fault signaling.
Availability
LT3755IUD-1#PBF is available at Aetrix Electronics and suitable for automotive LED headlamps, battery-powered portable lighting, and industrial signage requiring stable component supply, AEC-Q100 compliance, and frequency synchronization capability.
Supply support for LT3755IUD-1#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 is a global leader in high-performance analog, mixed-signal, and digital signal processing semiconductors, serving industrial, automotive, communications, and healthcare markets.
The LT3755 family is designed specifically for high-reliability, high-efficiency LED current regulation in demanding environments-emphasizing automotive-grade thermal performance, flexible topology support, and integrated protection features.
FAQ
What is the primary function of the SYNC pin on the LT3755IUD-1#PBF?
The SYNC pin on the LT3755IUD-1#PBF replaces the OPENLED function found on non–1 variants and enables external clock synchronization of the internal oscillator. It accepts a logic-level square wave to lock switching frequency and phase-reducing EMI peaks and enabling deterministic timing in multi-converter systems. The LT3755IUD-1#PBF requires the external clock to run 20% faster than the RT-set frequency for reliable operation, and the PWM rising edge must precede SYNC by ≥200ns for optimal dimming fidelity.
How does the LT3755IUD-1#PBF implement open LED detection without an OPENLED pin?
The LT3755IUD-1#PBF does not provide dedicated open LED reporting because its Pin 9 is assigned to SYNC instead of OPENLED. Open-circuit detection must be implemented externally-typically by monitoring FB voltage with a comparator circuit that triggers when FB exceeds VFB – 50mV (1.20V typical). This differs from LT3755IUD#PBF and LT3755IUD-2#PBF, which assert OPENLED internally. System designers using LT3755IUD-1#PBF must allocate additional components for fault signaling.
What is the maximum output voltage supported by the LT3755IUD-1#PBF?
The LT3755IUD-1#PBF supports output voltages up to 75V, as confirmed by Absolute Maximum Ratings (ISP/ISN pins rated to 75V) and Typical Application circuits achieving 50W LED string operation at 75V. This rating applies regardless of topology-boost, buck, buck-boost, SEPIC, or flyback-as long as external components (MOSFET, diode, inductor, capacitors) are rated accordingly. The 75V limit ensures safe operation with standard 100V-rated power semiconductors.
Can the LT3755IUD-1#PBF operate in constant-voltage mode?
Yes, the LT3755IUD-1#PBF supports constant-voltage regulation via its FB pin, which is internally referenced to 1.25V. When configured with a resistive divider from output to FB, the controller regulates output voltage instead of LED current. In this mode, the ISP/ISN current sense loop remains active but is overridden by the voltage loop-provided FB remains within its valid range. The device also provides FB overvoltage protection (PWMOUT forced low if FB > VFB + 60mV) and open-LED detection (via FB drop) when used in CV mode.
What thermal management requirements apply to the LT3755IUD-1#PBF in high-power LED applications?
The LT3755IUD-1#PBF requires soldering of its exposed thermal pad (Pin 17) directly to a PCB ground plane to achieve θJA = 68°C/W. For continuous 50W LED driver operation, a minimum 250mm² copper area with 2–4 thermal vias (0.3mm diameter, spaced ≤1mm apart) beneath the pad is recommended. Junction temperature must remain ≤125°C; derating is required above 85°C ambient. Thermal shutdown activates at 165°C, but sustained operation above 125°C degrades long-term reliability per Analog Devices' characterization data.
LT3755IUD-1#PBF Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- -
- Package/Case:
- 16-WFQFN 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:
- -40°C ~ 125°C (TJ)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 16-QFN (3x3)
LT3755IUD-1#PBF FAQ
1.How can I place an order for LT3755IUD-1#PBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LT3755IUD-1#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 LT3755IUD-1#PBF reliable?
The price and inventory of LT3755IUD-1#PBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LT3755IUD-1#PBF is usually 5 days.
3.What payment methods are accepted for LT3755IUD-1#PBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LT3755IUD-1#PBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LT3755IUD-1#PBF?
LT3755IUD-1#PBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LT3755IUD-1#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 LT3755IUD-1#PBF?
For technical support, including LT3755IUD-1#PBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LT3755IUD-1#PBF requirements.
6.How does Aetrix verify that LT3755IUD-1#PBF is sourced from the original manufacturer or authorized distributors?
All LT3755IUD-1#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 LT3755IUD-1#PBF meets industry standards.
7.What is the process for return or replacement of LT3755IUD-1#PBF?
All LT3755IUD-1#PBF units undergo pre-shipment inspection (PSI). If there is an issue with LT3755IUD-1#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 LT3755IUD-1#PBF part is unused and in its original packaging.
Return procedure for LT3755IUD-1#PBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
LT3755IUD-1#PBF Tags
-
BCR402RE6327HTSA1
Infineon Technologies
-
BCR430UXTSA2
Infineon Technologies
-
BCR420UE6433HTMA1
Infineon Technologies
-
BCR420UE6327HTSA1
Infineon Technologies
-
BCR421UE6327HTSA1
Infineon Technologies
-
LYT1604D-TL
Power Integrations
-
HV9910CLG-G
Microchip Technology
-
CL2N8-G
Microchip Technology
-
BCR420UW6-7
Diodes Incorporated
-
BCR421UW6-7
Diodes Incorporated
-
BCR420UFD-7
Diodes Incorporated
-
BCR421UFD-7
Diodes Incorporated
Tech Hub
A practical engineering guide to 3.3V and 5V logic compatibility, input thresholds, resistor dividers, translator ICs, MOSFET level shifting, I2C pull-ups, timing limits and power-sequencing risks.
The 74HC595 uses push-pull logic outputs, while the TPIC6B595 uses 50 V open-drain DMOS sinks for higher-power loads. This guide compares timing, current limits, 3.3 V interfacing, load wiring, thermal…
The 74HC595 converts serial data into eight stable parallel outputs. This guide covers pin functions, shift and storage timing, OE and MR behavior, drive-current limits, cascading, voltage compatibilit…
A technical comparison of level-sensitive latches and edge-triggered flip-flops, covering timing windows, setup and hold limits, master–slave operation, time borrowing, race-through, HDL inference and…
A D latch stores one bit while Enable controls when data can pass. This reference covers gate-level operation, truth tables, transparency, setup and hold timing, LE versus OE, common ICs and practical …
An SR latch stores one bit through cross-coupled feedback. This engineering reference covers NOR and NAND implementations, truth tables, forbidden-state recovery, gated operation, switch debouncing, fa…
Latch circuits retain one bit through feedback. This technical reference covers SR and D latches, truth tables, transparency, timing limits, latch-versus-flip-flop behavior, applications and common log…
An engineering guide to LED driver operation, constant-current and constant-voltage outputs, linear and switching topologies, dimming, IC selection, calculations, replacement compatibility, and fault c…
Operational amplifier guide covering op amp basics, feedback, ideal vs real op amps, common configurations, buffer circuits, offset, bias current, gain-bandwidth, slew rate, rail-to-rail limits and sel…
Jumper cables guide covering safe connection order, red and black clamp placement, final ground connection, cable gauge, length, clamp quality, copper vs CCA cables, jump starter comparison and battery…
