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Analog Devices Inc. LT3491EDC#TRPBF
- Part No.:
- LT3491EDC#TRPBF
- Manufacturer:
- Analog Devices Inc.
- Category:
- LED Drivers
- Package:
- 6-WFDFN Exposed Pad
- Datasheet:
-
LT3491EDC#TRPBF.pdf
- Description:
- IC LED DRVR RGLTR PWM 260MA 6DFN
- Quantity:
- Payment:
- Shipping:
Inventory:474
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Product details
Overview
LT3491EDC#TRPBF from Analog Devices (formerly Linear Technology) is a fixed-frequency step-up 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 in a 6-lead 2mm × 2mm DFN package.
For engineers reviewing the LT3491EDC#TRPBF datasheet, LT3491EDC#TRPBF pinout, LT3491EDC#TRPBF application, or LT3491EDC#TRPBF equivalent, key selection criteria include LED string count support (up to 6), high-side sense architecture enabling ground-referenced LED strings, 27V output clamp, 200mV current-sense voltage, and compatibility with low-ESR 1µF output capacitors.
Technical Context
The LT3491EDC#TRPBF employs constant-frequency current-mode control with internal ramp compensation for stable regulation across line and load variations. Its high-side current sense topology eliminates the need for ballast resistors and allows one-wire LED string connection by referencing the LED anode to ground.
It integrates a 27V overvoltage clamp on the CAP pin, a 200mV precision current-sense reference (VCAP – VLED), and a single CTRL pin that linearly modulates LED current from 0 to full scale (e.g., 20mA with 10Ω RSENSE) between 0V and 1.5V, while shutting down below 50mV.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| VIN Range | 2.5V to 12V - supports single Li-Ion (2.7–4.2V), dual alkaline (2–3.2V with auxiliary supply), or 3.3V/5V logic rails. |
| Switching Frequency | 2.3MHz (typ) - enables use of tiny 10µH inductors and 1µF ceramic capacitors, minimizing board area. |
| LED Current Sense Voltage | 200mV (±5%) - sets ILED = 200mV / RSENSE; enables precise, resistor-programmed current without external op-amps. |
| Open-LED Protection | 27V clamp (typ) - limits CAP voltage during LED string open-circuit fault, reducing stress on external components. |
| CTRL Pin Function | Single-pin analog dimming & shutdown - 0–1.5V controls LED current linearly; <50mV disables regulator. |
| Integrated Schottky | Forward drop ≤0.8V @ 100mA - eliminates external diode, reduces BOM count and thermal footprint. |
| Package | 6-Lead DFN (2mm × 2mm × 0.75mm) - exposes thermal pad for PCB grounding; θJA = 102°C/W. |
Pinout & Package
LT3491EDC#TRPBF is housed in a thermally enhanced 6-lead DFN package (2mm × 2mm × 0.75mm) with exposed pad (Pin 7) requiring solder connection to PCB ground for rated thermal performance (θJA = 102°C/W).
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| SW (Pin 1) | Power Switch Drain | Connects to inductor; high dv/dt node - minimize trace area to reduce EMI. |
| GND (Pin 2) | Ground Reference | Primary ground return for control circuitry and feedback; tie directly to local ground plane. |
| VIN (Pin 3) | Input Supply | 2.5V–12V input; requires local 1µF ceramic bypass capacitor. |
| CTRL (Pin 4) | Dimming & Shutdown Control | Analog input: 0–1.5V sets LED current; <50mV forces shutdown; must not float. |
| LED (Pin 5) | LED Anode / Sense Node | Connects to anode of first LED and RSENSE; high-side current sense point. |
| CAP (Pin 6) | Boost Output / Cathode Node | Output of boost stage; connects to cathode of LED string and output capacitor (1µF). |
| Exposed Pad (Pin 7) | Thermal & Electrical Ground | Mandatory PCB ground connection for thermal dissipation and noise reduction. |
Key Features
| Feature | Design Value |
|---|---|
| High-Side Current Sensing | Enables ground-referenced LED strings - simplifies mechanical layout and eliminates need for isolated sense resistors. |
| Integrated Schottky Diode | Reduces component count and board space; eliminates external diode selection, thermal management, and layout complexity. |
| Wide True Color PWM Dimming | 300:1 dimming range preserves LED chromaticity - avoids color shift by supporting both analog and direct PWM dimming schemes. |
| One-Pin Dimming & Shutdown | Reduces system GPIO usage; eliminates need for separate enable and brightness control lines in space-constrained portable designs. |
| 27V Open-LED Clamp | Prevents destructive overvoltage during LED failure or disconnection - protects downstream components without external clamping circuits. |
Applications
| Smartphone Backlight | Digital Camera Flash |
|---|---|
Use Scenario: Driving four white LEDs for LCD backlight in compact smartphones powered by single Li-Ion cells (3.0–4.2V). IC Role / Device Role / Timing Role: Constant-current boost controller with high-side sense and integrated Schottky. Use Value: Enables uniform brightness across LED string without ballast resistors; 2.3MHz operation allows ultra-small 10µH inductor and 1µF capacitor. | Use Scenario: Delivering pulsed 200mA current to two white LEDs in digital camera flash modules. IC Role / Device Role / Timing Role: High-efficiency boost driver with fast transient response and programmable current limit. Use Value: Supports torch mode (100mA) and flash mode (200mA) via CTRL voltage scaling; 27V clamp prevents damage during LED disconnect events. |
| GPS Receiver Display | MP3 Player UI Lighting |
Use Scenario: Powering three white LEDs for high-contrast monochrome display backlight in GPS handheld units. IC Role / Device Role / Timing Role: Low-quiescent-current LED driver optimized for battery life in always-on navigation devices. Use Value: 8µA shutdown current extends battery runtime; wide 2.5–12V input accommodates aging Li-Ion and backup coin-cell scenarios. | Use Scenario: Controlling brightness of status LEDs and OLED segment backlights in portable audio players. IC Role / Device Role / Timing Role: Single-pin dimming interface compatible with microcontroller DAC or filtered PWM outputs. Use Value: 300:1 true-color dimming range maintains consistent white point across all brightness levels - critical for user interface fidelity. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar white LED boost driver applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LT3465EDD#TRPBF | 2.7MHz switching, 1.9mA quiescent current, same 6-lead DFN package but no exposed pad; lower max duty cycle (85%). | Optimized for higher efficiency at light loads; less suitable for 6-LED strings at 12V input due to lower VOUT capability. | Select when prioritizing ultra-low IQ and 2.7MHz operation; verify thermal margin without exposed pad. |
| LT1937EDD#TRPBF | 1.2MHz switching, 1.9mA IQ, supports up to 4 LEDs, 10V max VIN, ThinSOT-6 package (3mm × 3mm). | Smaller LED string count and input voltage range; larger footprint than DFN; lacks 27V open-LED clamp. | Choose for cost-sensitive 4-LED designs with <10V input; avoid for 6-LED or >10V systems requiring robust fault protection. |
Compared with LT3465EDD#TRPBF and LT1937EDD#TRPBF, LT3491EDC#TRPBF offers superior open-LED protection (27V clamp vs none or 34V unclamped), higher LED string capacity (6 vs 4 or 6 with reduced headroom), and thermally optimized DFN packaging - making it preferred for ruggedized portable displays requiring fault resilience and minimal board area.
Availability
LT3491EDC#TRPBF is available at Aetrix Electronics and suitable for smartphone backlighting, digital camera flash modules, GPS receiver displays, and MP3 player UI lighting requiring stable component supply and long-term industrial availability.
Supply support for LT3491EDC#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 acquired Linear Technology in 2017 and maintains its high-performance analog IC portfolio, emphasizing precision power management, signal conditioning, and timing solutions for demanding industrial and portable applications.
The LT3491EDC#TRPBF belongs to Linear's white LED boost driver product line, engineered specifically for space-constrained portable electronics where uniform LED brightness, minimal external components, and robust fault protection are critical design requirements.
FAQ
What is the maximum number of white LEDs the LT3491EDC#TRPBF can drive?
The LT3491EDC#TRPBF can drive up to six white LEDs in series from a 3V supply, as confirmed in the device description and typical application circuits. This assumes forward voltage per LED ≤3.5V (e.g., 6 × 3.3V = 19.8V), staying within the 27V open-LED clamp and 32V absolute max LED pin rating. The LT3491EDC#TRPBF datasheet explicitly states "Drives Up to Six White LEDs from a 3V Supply" and validates this in TA06a/b.
Does the LT3491EDC#TRPBF require an external Schottky diode?
No, the LT3491EDC#TRPBF integrates a Schottky diode internally, as stated in the features list ("Internal Schottky Diode") and confirmed in the block diagram and absolute maximum ratings (Schottky Forward Drop ≤0.8V @ 100mA). This eliminates the need for an external diode, reducing BOM count and PCB area - a key differentiator versus discrete boost controllers.
What is the purpose of the exposed pad on the LT3491EDC#TRPBF DFN package?
The exposed pad (Pin 7) on the LT3491EDC#TRPBF DFN package must be soldered to the PCB ground plane to achieve the specified thermal performance (θJA = 102°C/W). It serves both thermal dissipation and electrical grounding functions. The datasheet explicitly states: "EXPOSED PAD (PIN 7) SHOULD BE CONNECTED TO PCB GROUND" and provides solder pad layout guidelines to ensure reliability.
How does the LT3491EDC#TRPBF implement high-side current sensing?
The LT3491EDC#TRPBF implements high-side current sensing by measuring the voltage difference between CAP and LED pins (VCAP – VLED = 200mV), which corresponds to the current through the external sense resistor RSENSE. This architecture allows the LED string's cathode to connect directly to ground - enabling "one wire current source" operation and eliminating the need for a grounded sense resistor. The LT3491EDC#TRPBF block diagram and functional description confirm this topology.
Can the LT3491EDC#TRPBF operate from a 2.5V input supply?
Yes, the LT3491EDC#TRPBF supports a minimum input voltage of 2.5V, as specified in the "VIN Range: 2.5V to 12V" feature and confirmed in the Absolute Maximum Ratings table. This enables operation from deeply discharged Li-Ion cells or dual alkaline batteries. The datasheet also includes a dedicated "Low Input Voltage Applications" section (Figure 10) demonstrating use with 2V–3.2V AA cells when powered via auxiliary 3.3V logic rail.
LT3491EDC#TRPBF 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#TRPBF FAQ
1.How can I place an order for LT3491EDC#TRPBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LT3491EDC#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 LT3491EDC#TRPBF reliable?
The price and inventory of LT3491EDC#TRPBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LT3491EDC#TRPBF is usually 5 days.
3.What payment methods are accepted for LT3491EDC#TRPBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LT3491EDC#TRPBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LT3491EDC#TRPBF?
LT3491EDC#TRPBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LT3491EDC#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 LT3491EDC#TRPBF?
For technical support, including LT3491EDC#TRPBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LT3491EDC#TRPBF requirements.
6.How does Aetrix verify that LT3491EDC#TRPBF is sourced from the original manufacturer or authorized distributors?
All LT3491EDC#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 LT3491EDC#TRPBF meets industry standards.
7.What is the process for return or replacement of LT3491EDC#TRPBF?
All LT3491EDC#TRPBF units undergo pre-shipment inspection (PSI). If there is an issue with LT3491EDC#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 LT3491EDC#TRPBF part is unused and in its original packaging.
Return procedure for LT3491EDC#TRPBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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