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Analog Devices Inc. LT3935RV#PBF
- Part No.:
- LT3935RV#PBF
- Manufacturer:
- Analog Devices Inc.
- Category:
- LED Drivers
- Package:
- 28-TFQFN Exposed Pad
- Datasheet:
-
LT3935RV#PBF.pdf
- Description:
- IC LED DRVR RGLTR PWM 4A 28LQFN
- Quantity:
- Payment:
- Shipping:
Inventory:613
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Product details
Overview
LT3935RV#PBF from Analog Devices is a 36V, 4A synchronous step-down LED driver with Silent Switcher architecture, fixed-frequency peak-current control, and PWM/analog dimming capability. It regulates LED string current with ±1.5% accuracy, supports 0V–36V output voltage range, and integrates open/short LED fault detection for automotive lighting systems.
For engineers reviewing the LT3935RV#PBF datasheet, LT3935RV#PBF pinout, LT3935RV#PBF application, or LT3935RV#PBF equivalent, key selection criteria include input voltage range (3.6V–36V), programmable switching frequency (200kHz–2MHz), spread-spectrum EMI reduction, thermal shutdown, and fault reporting via open-drain FAULT pin.
Technical Context
The LT3935RV#PBF implements fixed-frequency, peak-current-mode control with dual regulation loops: one for LED current (via ISP/ISN sense and CTRL programming) and another for output voltage limiting (via FB pin and internal 1.000V reference). Its Silent Switcher topology minimizes EMI through symmetrical layout and integrated charge pump for BST drive.
It features dual fault detection-open-circuit (FB > 950mV + ISP−ISN < 10mV) and short-circuit (FB < 200mV)-with latch-off or hiccup restart selectable via SS pin resistor. The device operates across −40°C to +150°C junction temperature and uses proprietary valley-current limiting (DA limit ≈6.4A) to prevent inductor saturation during low-VOUT conditions.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 3.6V to 36V - supports wide-range industrial and automotive battery inputs without external pre-regulation. |
| Max LED Current | 4A - enables high-brightness single-string LED arrays (e.g., 3× high-power LEDs at 4A). |
| Current Regulation Accuracy | ±1.5% - ensures consistent luminance across temperature and unit-to-unit variation. |
| Switching Frequency Range | 200kHz to 2MHz - allows trade-off between component size (higher fSW → smaller L/C) and efficiency/EMI. |
| Output Voltage Limit | Programmable via FB divider - protects LED string from overvoltage by clamping VOUT when FB ≥1.05V. |
| Fault Reporting | Open-drain FAULT pin - pulls low for open-circuit (FB > 950mV) or short-circuit (FB < 200mV) conditions. |
| Junction Temp Range | −40°C to +150°C - qualified for under-hood automotive and high-ambient industrial environments. |
Pinout & Package
LT3935RV#PBF is housed in a thermally enhanced 28-lead LQFN package (5mm × 4mm × 0.94mm) with exposed GND pad (Pin 29) requiring PCB soldering for thermal and electrical integrity. Pin count and layout match standard 4mm × 5mm QFN footprints.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| VIN (Pins 1, 24) | Input power supply | Supplies analog circuitry and high-side switch; requires local ceramic bypassing to GND. |
| ISP / ISN (Pins 6, 5) | Current sense differential inputs | Measure voltage across external sense resistor (e.g., 25mΩ); enable ±1.5% LED current regulation. |
| CTRL (Pin 18) | LED current programming input | Accepts 250mV–1.25V analog voltage or 12.5%–62.5% duty-cycle pulses to set regulated current. |
| FB (Pin 4) | Output voltage feedback | Monitors LED string voltage via resistor divider; triggers overvoltage lockout at 1.05V. |
| FAULT (Pin 7) | Open-drain fault indicator | Pulls low for open-circuit (FB > 950mV) or short-circuit (FB < 200mV); requires 100kΩ pull-up to INTVCC. |
| RT (Pin 10) | Frequency programming | Resistor to GND sets switching frequency (e.g., 45.3kΩ = 2MHz); enables EMI optimization. |
| SYNC/SPRD (Pin 19) | External clock or SSFM control | Tied to INTVCC enables spread-spectrum modulation; tied to GND disables synchronization. |
| SW (Pins 14, 15) | Power switch node | Internally connected; drives external inductor; switches between VIN and GND at programmed fSW. |
Key Features
| Feature | Design Value |
|---|---|
| Silent Switcher® architecture | Reduces radiated/conducted EMI by >30dB at fundamental and harmonics vs. conventional buck converters. |
| Spread-spectrum frequency modulation | Varies switching frequency ±25% around RT-set value to smear EMI peaks and pass CISPR 25 Class 5. |
| Integrated LED current monitor (ISMON) | Provides buffered 10mV/mV output proportional to ISP−ISN, enabling real-time current diagnostics. |
| Accurate EN/UVLO threshold | 1.16V rising threshold with 20mV hysteresis ensures clean startup/shutdown across temperature. |
| Thermal shutdown protection | Activates above +150°C junction temperature; latches off until thermal recovery and EN reassertion. |
Applications
| Automotive Headlamp Driver | Industrial High-Bay Lighting |
|---|---|
Use Scenario: Driving 3× high-power white LEDs (≈9V, 4A) in vehicle headlamps with strict EMI limits per CISPR 25. IC Role / Device Role / Timing Role: Primary LED current regulator with fault reporting, UVLO, and spread-spectrum EMI suppression. Use Value: Enables direct 12V/24V battery operation without external pre-regulator while meeting automotive EMC requirements. | Use Scenario: Powering long LED strings (up to 36V) in warehouse high-bay fixtures requiring stable current over wide ambient temperature ranges. IC Role / Device Role / Timing Role: Synchronous buck controller with ±1.5% current accuracy and −40°C to +150°C operation. Use Value: Eliminates need for external current-sense amplifiers and improves system reliability in uncooled enclosures. |
| RGB LED Color Mixing Module | UV-C Sterilization System |
Use Scenario: Independently dimming red/green/blue LED channels using PWM input on CTRL pin for precise color calibration. IC Role / Device Role / Timing Role: Dimmable LED driver supporting 100kHz–1MHz digital CTRL pulses for flicker-free color control. Use Value: Achieves 20:1 dimming ratio without analog DACs, reducing BOM cost and board space. | Use Scenario: Driving high-current UV-C LED strings (e.g., 365nm, 4A) in medical sterilization devices requiring fault-safe operation. IC Role / Device Role / Timing Role: Fault-tolerant LED driver with open/short detection and latch-off mode to prevent hazardous overcurrent. Use Value: Ensures immediate shutdown on LED string failure, protecting both user safety and optical components. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar LED driver applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LTC3783EFE#PBF | Non-synchronous boost/buck-boost LED driver; no integrated MOSFETs; requires external high-side switch. | Supports >36V output but lacks Silent Switcher EMI performance and integrated fault reporting. | Choose for boost-topology designs where input < VOUT; avoid for EMI-sensitive automotive applications. |
| LM3409QMY/NOPB | Asynchronous buck LED driver; 1A max current; no spread spectrum; lower integration (no ISMON, no SSFM). | Qualified for automotive AEC-Q100 Grade 1 only; not rated for 150°C junction operation. | Use for cost-sensitive, lower-current (<1.5A) industrial lighting where full LT3935 feature set is unnecessary. |
Compared with LTC3783EFE#PBF and LM3409QMY/NOPB, the LT3935RV#PBF delivers higher integration (4A synchronous switch, ISMON, FAULT), superior EMI performance via Silent Switcher, and extended temperature capability - making it optimal for high-reliability, high-current automotive and industrial LED systems where compact layout and regulatory compliance are critical.
Availability
LT3935RV#PBF is available at Aetrix Electronics and suitable for automotive headlamps, industrial high-bay lighting, and UV-C sterilization systems requiring stable component supply, long-term lifecycle support, and RoHS/WEEE compliance.
Supply support for LT3935RV#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, Inc. is a global leader in high-performance analog, mixed-signal, and digital signal processing semiconductors, serving precision instrumentation, industrial automation, and automotive markets.
The LT3935RV#PBF belongs to Analog Devices' Silent Switcher LED driver product line, engineered specifically for low-EMI, high-current DC/DC conversion in demanding automotive and industrial lighting applications.
FAQ
What is the maximum LED string voltage supported by the LT3935RV#PBF?
The LT3935RV#PBF supports up to 36V LED string voltage, as confirmed by its absolute maximum rating of 0V to 36V on the VOUT pin and ISP/ISN common-mode range of 0V to 36V. This allows direct driving of multi-LED strings without external voltage boosting, provided input voltage exceeds VOUT by sufficient margin for regulation.
Does the LT3935RV#PBF require an external current sense resistor, and what value is typical?
Yes, the LT3935RV#PBF requires an external current sense resistor between ISP and ISN. A 25mΩ resistor is typical for 4A operation, yielding 100mV sense voltage at full scale - matching the device's maximum programmable sense voltage and ensuring ±1.5% current regulation accuracy across temperature.
How does spread-spectrum frequency modulation work on the LT3935RV#PBF?
Spread-spectrum frequency modulation on the LT3935RV#PBF is enabled by tying the SYNC/SPRD pin to INTVCC, causing the switching frequency to vary continuously from 100% to 125% of the RT-resistor-set value. This smears EMI energy across a wider bandwidth, reducing peak emissions by up to 20dB and aiding compliance with CISPR 25 and FCC Part 15.
Can the LT3935RV#PBF operate with input voltage below the LED string voltage?
No - the LT3935RV#PBF is a step-down (buck) converter only and cannot regulate LED current when VIN < VOUT. Its operating principle requires VIN to exceed VOUT by at least the sum of switch drops and inductor DCR. For boost or buck-boost topologies, alternative drivers like the LTC3783EFE#PBF must be used instead of the LT3935RV#PBF.
What fault conditions trigger the FAULT pin on the LT3935RV#PBF?
The FAULT pin on the LT3935RV#PBF pulls low for two confirmed conditions: (1) open-circuit LED string (FB > 950mV AND ISP−ISN < 10mV), and (2) short-circuited LED string (FB < 200mV). Both are detected internally and reported via the open-drain FAULT output, which requires a 100kΩ pull-up to INTVCC for proper logic-level signaling.
LT3935RV#PBF Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- -
- Package/Case:
- 28-TFQFN Exposed Pad
- Packaging:
- Tray
- Product Status:
- Active
- Type:
- DC DC Regulator
- Topology:
- Step-Down (Buck)
- Internal Switch(s):
- Yes
- Number of Outputs:
- 1
- Voltage - Supply (Min):
- 3.6V
- Voltage - Supply (Max):
- 36V
- Voltage - Output:
- 0V ~ 36V
- Current - Output / Channel:
- 4A
- Frequency:
- 200kHz ~ 2MHz
- Dimming:
- PWM
- Applications:
- Lighting
- Operating Temperature:
- -40°C ~ 150°C (TJ)
- Grade:
- Automotive
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 28-LQFN (4x5)
LT3935RV#PBF FAQ
1.How can I place an order for LT3935RV#PBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LT3935RV#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 LT3935RV#PBF reliable?
The price and inventory of LT3935RV#PBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LT3935RV#PBF is usually 5 days.
3.What payment methods are accepted for LT3935RV#PBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LT3935RV#PBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LT3935RV#PBF?
LT3935RV#PBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LT3935RV#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 LT3935RV#PBF?
For technical support, including LT3935RV#PBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LT3935RV#PBF requirements.
6.How does Aetrix verify that LT3935RV#PBF is sourced from the original manufacturer or authorized distributors?
All LT3935RV#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 LT3935RV#PBF meets industry standards.
7.What is the process for return or replacement of LT3935RV#PBF?
All LT3935RV#PBF units undergo pre-shipment inspection (PSI). If there is an issue with LT3935RV#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 LT3935RV#PBF part is unused and in its original packaging.
Return procedure for LT3935RV#PBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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