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Analog Devices Inc. LT3491EDC#TRMPBF
- Part No.:
- LT3491EDC#TRMPBF
- Manufacturer:
- Analog Devices Inc.
- Category:
- LED Drivers
- Package:
- 6-WFDFN Exposed Pad
- Datasheet:
-
LT3491EDC#TRMPBF.pdf
- Description:
- IC LED DRVR RGLTR PWM 260MA 6DFN
- Quantity:
- Payment:
- Shipping:
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Product details
Overview
LT3491EDC#TRMPBF from Analog Devices (formerly Linear Technology) is a fixed-frequency, current-mode boost DC/DC converter IC designed to drive up to six white LEDs in series from a 2.5V–12V input, featuring integrated Schottky diode, high-side current sensing, and single-pin PWM dimming/shutdown control. It delivers ±5% reference accuracy, 2.3MHz switching, and 27V open-LED protection for portable Li-Ion-powered backlighting in digital cameras and GPS receivers.
For engineers reviewing the LT3491EDC#TRMPBF datasheet, LT3491EDC#TRMPBF pinout, LT3491EDC#TRMPBF application, or LT3491EDC#TRMPBF equivalent, key selection criteria include its 6-lead 2mm × 2mm DFN package, 200mV LED current sense voltage, 260–350mA switch current limit, internal Schottky diode, and compatibility with 1µF output capacitance - all critical for space-constrained, high-efficiency LED driver designs.
Technical Context
The LT3491EDC#TRMPBF employs constant-frequency current-mode control with an internal 1.25V bandgap reference and ramp-compensated PWM comparator to regulate LED current via high-side sensing across the CAP–LED differential. Its oscillator operates at 2.3MHz (1.8–2.8MHz range), enabling use of miniature 10µH inductors and ceramic capacitors while maintaining stable regulation under line and load transients.
Shutdown and analog dimming are unified on the CTRL pin: device enables above 100mV, fully regulates LED current at 1.5V, and disables below 50mV. The internal Schottky diode (0.8V forward drop at 100mA, 4µA leakage at 20V) eliminates external diode requirements, and open-circuit protection clamps CAP at 27V (typ) during LED string failure.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| VIN Range | 2.5V to 12V - supports single-cell Li-Ion (2.7–4.2V) and dual-cell alkaline (2–3.2V) inputs without external regulators. |
| Switching Frequency | 2.3MHz (1.8–2.8MHz) - enables compact 10µH inductors and 1µF ceramic output capacitors, reducing board area and EMI filter size. |
| LED Current Sense Voltage | 200mV (190–210mV) - sets ILED = 200mV/RSENSE; enables precise current programming with standard 1% resistors (e.g., 10Ω → 20mA). |
| Open-LED Protection | 27V clamp (26–28V) - prevents overvoltage damage during LED string disconnection or open-circuit failure; reduces input current automatically. |
| Switch Current Limit | 350mA (max) - limits peak inductor current to protect internal MOSFET and ensure reliable operation with 10µH inductors. |
| Package | 6-Lead DFN (2mm × 2mm × 0.75mm) - low-profile, thermally enhanced package with exposed pad tied to PCB ground for θJA = 102°C/W. |
| CTRL Pin Function | Single-pin dimming/shutdown - 0–1.5V analog control provides 300:1 true-color PWM dimming range; <50mV disables IC. |
Pinout & Package
LT3491EDC#TRMPBF uses a 6-lead plastic DFN package (2mm × 2mm × 0.75mm) with exposed thermal pad (Pin 7) requiring connection to PCB ground for rated thermal performance (θJA = 102°C/W). The SC70 variant (LT3491ESC8) is pin-compatible but larger; this part is exclusively DFN.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| SW (Pin 1) | Internal Power Switch Drain | Connects to inductor; high dv/dt node - minimize trace area to reduce EMI and ringing. |
| GND (Pin 2) | Power Ground | Primary ground return for switch, bias, and feedback; tie directly to local ground plane. |
| CTRL (Pin 3) | Dimming & Shutdown Control | 0–1.5V analog input sets LED current; <50mV disables regulator; must not float. |
| LED (Pin 4) | High-Side Current Sense Input | Connects to LED string anode and RSENSE; enables "one-wire" LED connection by referencing current sense to LED cathode side. |
| CAP (Pin 5) | Boost Output / Schottky Cathode | Output node connected to internal Schottky cathode; place 1µF ceramic capacitor here for stability and ripple reduction. |
| VIN (Pin 6) | Input Supply | 2.5–12V input; requires local 1µF ceramic bypass capacitor near pin. |
Key Features
| Feature | Design Value |
|---|---|
| Integrated Schottky Diode | Eliminates external diode, saves board space, and reduces BOM count; rated for 1A inrush and 100mA continuous (0.8V VF). |
| High-Side Current Sensing | Enables grounded LED cathode configuration - simplifies mechanical layout and eliminates need for ballast resistors or floating sense circuits. |
| 27V Open-LED Clamp | Protects downstream components during LED string failure; reduces input current and prevents CAP overvoltage without external Zener or TVS. |
| 2.3MHz Fixed Switching | Allows use of tiny 10µH inductors (e.g., Murata LQH32CN100) and 1µF X5R/X7R ceramics, minimizing solution footprint and cost. |
| 300:1 True-Color PWM Dimming | Maintains consistent LED chromaticity across full brightness range by avoiding analog current modulation below 1.5V CTRL threshold. |
Applications
| Digital Camera Backlight | GPS Receiver Display |
|---|---|
Use Scenario: Driving four white LEDs in series for LCD backlight in compact handheld digital cameras powered by single Li-Ion cell (3.0–4.2V). IC Role / Device Role / Timing Role: Boost converter with integrated Schottky and high-side sensing provides regulated 20mA per LED string with minimal external components. Use Value: Enables uniform brightness, eliminates ballast resistors, and achieves >70% efficiency at 3.6V input - extending battery life and reducing thermal load. | Use Scenario: Powering three white LEDs for monochrome segment display in automotive-grade GPS receivers operating across –40°C to 85°C. IC Role / Device Role / Timing Role: Constant-current LED driver with 27V open-circuit protection ensures reliability during cold-start or LED failure conditions. Use Value: Maintains display visibility under wide input voltage (2.5–12V) and temperature ranges without derating; exposed-pad DFN ensures thermal stability. |
| MP3 Player UI Lighting | PDA Keypad Illumination |
Use Scenario: Dimmable backlight for OLED or segmented UI in portable MP3 players using 3.3V logic rail as VIN source. IC Role / Device Role / Timing Role: Single-pin CTRL interface accepts filtered PWM or DC voltage for smooth brightness control without color shift. Use Value: Achieves 300:1 dimming range with true-color fidelity; 2.3MHz operation avoids audible noise in audio-sensitive environments. | Use Scenario: Driving six white LEDs in series for keypad backlight in ruggedized PDAs with limited PCB real estate. IC Role / Device Role / Timing Role: High-efficiency boost topology with integrated Schottky supports full-string operation from 2.5V minimum input. Use Value: Reduces component count to just inductor, two 1µF caps, and one sense resistor - cutting BOM cost and assembly steps. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar white LED driver applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LT3465EDD#TRPBF | 2.7MHz switching, higher IQ (1.9mA), same 6-lead DFN package, identical 200mV sense voltage and 27V OVP. | Optimized for ultra-low-noise applications; slightly higher quiescent current but faster transient response. | Preferred when higher switching frequency is needed to shrink inductor size further or avoid AM radio band interference. |
| LT1937ES5#TRMPBF | 1.2MHz switching, ThinSOT-5 package (smaller footprint but no exposed pad), 200mV sense, 34V OVP, lower max VIN (10V). | Limited to ≤10V input; lacks thermal pad - less suitable for sustained high-current operation in confined spaces. | Select when board height is constrained below 0.75mm and input voltage never exceeds 10V; verify thermal margin at full load. |
Compared with LT3491EDC#TRMPBF, LT3465EDD#TRPBF offers faster switching for smaller passives but higher quiescent current, while LT1937ES5#TRMPBF trades thermal performance and input range for minimal footprint - making LT3491EDC#TRMPBF optimal for balanced efficiency, thermal management, and 12V tolerance in portable lighting.
Availability
LT3491EDC#TRMPBF is available at Aetrix Electronics and suitable for digital camera backlighting, GPS receiver displays, and MP3 player UI lighting requiring stable component supply, long-lifecycle support, and RoHS-compliant packaging.
Supply support for LT3491EDC#TRMPBF 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 acquired Linear Technology in 2017 and maintains full technical and manufacturing continuity for legacy Linear power products.
The LT3491EDC#TRMPBF belongs to Linear's high-efficiency LED driver product line, engineered specifically for portable consumer electronics requiring compact, integrated boost solutions with robust fault protection and precision current regulation.
FAQ
What is the maximum number of white LEDs the LT3491EDC#TRMPBF can drive?
The LT3491EDC#TRMPBF can drive up to six white LEDs in series from a 3V supply, as confirmed in the datasheet's front-page description and Typical Application Circuits (e.g., Figure TA06a/b). This assumes typical forward voltage of ~3.2V per LED (19.2V total), within the device's 27V open-LED clamp and 32V absolute max CAP voltage rating. Performance depends on inductor selection and input voltage headroom.
Does the LT3491EDC#TRMPBF require an external Schottky diode?
No, the LT3491EDC#TRMPBF integrates a Schottky diode with 0.8V forward drop at 100mA and 4µA leakage at 20V, eliminating the need for an external diode. This integration reduces component count, PCB area, and potential failure points - a key feature highlighted in the product description and Absolute Maximum Ratings table.
What is the recommended output capacitor value for the LT3491EDC#TRMPBF?
The datasheet specifies that only a 1µF ceramic output capacitor is required for stable operation of the LT3491EDC#TRMPBF. This value is validated across multiple application circuits (e.g., TA01a, TA04a, TA06a) and supported by capacitor selection guidance recommending X5R/X7R dielectrics for stable capacitance over temperature.
How does the CTRL pin function for dimming and shutdown in the LT3491EDC#TRMPBF?
The CTRL pin of the LT3491EDC#TRMPBF serves dual functions: it enables analog dimming (0–1.5V) to set LED current proportionally and triggers shutdown (<50mV). At 1.5V, full current is delivered; above 1.5V, current remains constant. This behavior is documented in Electrical Characteristics (VCTRL for Full LED Current = 1.5V, VCTRL to Shut Down = 50mV) and Operation section.
Is the LT3491EDC#TRMPBF compatible with 2mm × 2mm DFN layout footprints used for other Linear LED drivers?
Yes, the LT3491EDC#TRMPBF uses the standard 6-lead DFN (2mm × 2mm) package defined in LTC DWG #05-08-1703, matching footprint dimensions (2.00±0.10mm × 2.00±0.10mm) and pad pitch (0.61±0.05mm) of related parts like LT3465EDD. The exposed thermal pad (0.56±0.05mm × 0.56±0.05mm) must be soldered to PCB ground for thermal compliance.
LT3491EDC#TRMPBF Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- -
- Package/Case:
- 6-WFDFN Exposed Pad
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Active
- Type:
- DC DC Regulator
- Topology:
- Step-Up (Boost)
- Internal Switch(s):
- Yes
- Number of Outputs:
- 1
- Voltage - Supply (Min):
- 2.5V
- Voltage - Supply (Max):
- 12V
- Voltage - Output:
- 27V
- Current - Output / Channel:
- 260mA (Switch)
- Frequency:
- 2.3MHz
- Dimming:
- PWM
- Applications:
- Backlight
- Operating Temperature:
- -40°C ~ 85°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 6-DFN (2x2)
LT3491EDC#TRMPBF FAQ
1.How can I place an order for LT3491EDC#TRMPBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LT3491EDC#TRMPBF 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 LT3491EDC#TRMPBF reliable?
The price and inventory of LT3491EDC#TRMPBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LT3491EDC#TRMPBF is usually 5 days.
3.What payment methods are accepted for LT3491EDC#TRMPBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LT3491EDC#TRMPBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LT3491EDC#TRMPBF?
LT3491EDC#TRMPBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LT3491EDC#TRMPBF 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 LT3491EDC#TRMPBF?
For technical support, including LT3491EDC#TRMPBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LT3491EDC#TRMPBF requirements.
6.How does Aetrix verify that LT3491EDC#TRMPBF is sourced from the original manufacturer or authorized distributors?
All LT3491EDC#TRMPBF 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 LT3491EDC#TRMPBF meets industry standards.
7.What is the process for return or replacement of LT3491EDC#TRMPBF?
All LT3491EDC#TRMPBF units undergo pre-shipment inspection (PSI). If there is an issue with LT3491EDC#TRMPBF, 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 LT3491EDC#TRMPBF part is unused and in its original packaging.
Return procedure for LT3491EDC#TRMPBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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