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Analog Devices Inc. LT3491ESC8#TRMPBF
- Part No.:
- LT3491ESC8#TRMPBF
- Manufacturer:
- Analog Devices Inc.
- Category:
- LED Drivers
- Package:
- 8-VFSOP (0.049", 1.25mm Width)
- Datasheet:
-
LT3491ESC8#TRMPBF.pdf
- Description:
- IC LED DRV RGLTR PWM SC70-8
- Quantity:
- Payment:
- Shipping:
Inventory:1,412
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Product details
Overview
LT3491ESC8#TRMPBF from Analog Devices (formerly Linear Technology) is a fixed-frequency, current-mode step-up DC/DC converter IC designed to drive up to six white LEDs in series from a 2.5V–12V input supply. It integrates a Schottky diode, provides high-side LED current sensing for single-wire LED string connection, delivers ±5% reference accuracy, and operates at 2.3MHz switching frequency. It is used in portable backlighting applications including GPS receivers and digital cameras.
For engineers reviewing the LT3491ESC8#TRMPBF datasheet, LT3491ESC8#TRMPBF pinout, LT3491ESC8#TRMPBF application, or LT3491ESC8#TRMPBF equivalent, key selection criteria include open-LED protection voltage (27V), CTRL pin dimming/shutdown interface, 200mV current-sense reference, SC70-8 package thermal performance (θJA = 270°C/W), and compatibility with 1µF output capacitance.
Technical Context
The LT3491ESC8#TRMPBF employs constant-frequency current-mode control with internal ramp compensation to ensure stable regulation across line and load variations. Its high-side sense architecture eliminates ground-referenced ballast resistors and enables direct grounding of the LED cathode anywhere in the system.
Operation relies on an internal 1.25V bandgap reference, oscillator, PWM comparator (A2), and error amplifier (A1) that regulates peak inductor current by comparing VCAP–VLED against the scaled CTRL voltage. Shutdown occurs when CTRL falls below 50mV; full LED current is achieved when CTRL exceeds 1.5V.
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), or 3.3V logic-supplied operation |
| 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; precision resistor selection directly determines LED current accuracy |
| Open-LED Protection | 27V clamp (typ) - prevents overvoltage damage during LED string disconnection or open-circuit failure |
| CTRL Interface | Single-pin analog dimming & shutdown - 0–50mV = shutdown; 100–1500mV = linear LED current control; >1500mV = full current |
| Integrated Schottky | Forward drop ≤0.8V @ 100mA - eliminates external diode, reduces BOM count and layout complexity |
| Package | 8-Lead SC70 (SC8) - 2.2mm × 1.35mm footprint, exposed pad for thermal management, θJA = 270°C/W |
Pinout & Package
LT3491ESC8#TRMPBF is housed in an 8-lead plastic SC70 (SC8) package with exposed pad connected to PCB ground for thermal performance. Pin 1 is marked with a bar; top view orientation follows JEDEC MO-203 BA standard.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| SW (Pin 1) | Power switch drain node | Connects to inductor; high dv/dt node requiring minimal trace area to reduce EMI |
| GND (Pins 2, 3, 4) | Ground return paths | All three pins must be tied directly to local ground plane for low-impedance return and thermal conduction |
| VIN (Pin 5) | Input supply input | Bypass locally with ≥1µF ceramic capacitor; accepts 2.5V–12V input range |
| CTRL (Pin 6) | Dimming and shutdown control | 0–50mV = shutdown; 100–1500mV = proportional LED current; must not float |
| LED (Pin 7) | LED string anode & sense node | Connects to first LED anode and RSENSE; high-side current sense point enabling "one-wire" LED connection |
| CAP (Pin 8) | Boost output & Schottky cathode | Connects to output capacitor and RSENSE; clamped at 27V during open-LED fault |
Key Features
| Feature | Design Value |
|---|---|
| High-side current sensing | Enables LED string cathode grounding anywhere-eliminates need for dedicated ground-return wiring and simplifies mechanical integration |
| Integrated Schottky diode | Reduces external component count by one, avoids diode selection, layout, and thermal derating decisions |
| 27V open-LED protection | Prevents destructive overvoltage during LED failure or connector disconnect-no external clamp circuit required |
| 2.3MHz switching frequency | Permits use of 10µH inductors and 1µF ceramics-cuts solution size vs. lower-frequency boost drivers by >40% |
| Wide 300:1 true-color PWM dimming | Maintains consistent LED chromaticity across dimming range-critical for camera flash and display backlight color fidelity |
Applications
| Cellular Phone Backlight | Digital Camera Flash |
|---|---|
Use Scenario: Driving four white LEDs in series for main LCD backlight in GSM/UMTS handsets with Li-Ion battery input (3.0–4.2V). IC Role / Device Role / Timing Role: Constant-current boost controller providing regulated 20mA per LED with analog dimming via baseband processor GPIO. Use Value: High-side sensing allows direct LED cathode grounding to chassis, reducing EMI and simplifying flex-cable routing. | Use Scenario: Delivering 200mA pulsed current to a single high-brightness white LED for autofocus assist and flash illumination in compact digital cameras. IC Role / Device Role / Timing Role: High-efficiency boost driver operating in torch mode (100mA) and flash mode (200mA), controlled by dedicated camera ASIC. Use Value: 27V open-LED protection ensures robustness during hot-swap of LED modules; 2.3MHz operation minimizes inductor size in space-constrained lens barrels. |
| GPS Receiver Display | MP3 Player UI Lighting |
Use Scenario: Powering three white LEDs for monochrome segment LCD backlight in automotive-grade GPS navigation units powered from 12V vehicle supply via LDO pre-regulation. IC Role / Device Role / Timing Role: Step-up converter generating ~9.5V output from 3.3V logic rail to drive series-connected LEDs with precise current matching. Use Value: ±5% reference accuracy ensures uniform brightness across all segments; SC70-8 package fits tight bezel areas near display edge. | Use Scenario: Illuminating OLED status icons and button backlights in portable audio players using two AA cells (2.0–3.2V) as primary power source. IC Role / Device Role / Timing Role: Low-input-voltage boost driver supporting direct battery connection to inductor while chip is powered from 3.3V logic rail. Use Value: Enables >85% efficiency at 2.5V input-extending battery life without requiring separate 3.3V regulator for LED driver. |
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 |
|---|---|---|---|
| LT3465ESC8#TRMPBF | 2.7MHz switching, higher quiescent current (1.9mA vs. 4mA), same SC70-8 package, no open-LED clamp | Lacks 27V open-LED protection; requires external clamp for fault tolerance | Choose when higher frequency is prioritized over fault protection and board space is extremely constrained |
| LT1937ES5#TRMPBF | SC70-5 package, 1.2MHz, supports up to 4 LEDs, lower max VIN (10V), no integrated Schottky | Requires external Schottky diode and larger inductor; limited to lower LED count and input voltage | Choose for cost-sensitive designs with ≤4 LEDs and VIN ≤10V where external diode is acceptable |
Compared with LT3465ESC8#TRMPBF and LT1937ES5#TRMPBF, LT3491ESC8#TRMPBF uniquely combines integrated Schottky, 27V open-LED protection, and high-side sensing in SC70-8-making it optimal for robust, space-limited 4–6 LED backlighting where reliability and minimal BOM are critical.
Availability
LT3491ESC8#TRMPBF is available at Aetrix Electronics and suitable for cellular phones, digital cameras, and GPS receivers requiring stable component supply, long-term manufacturability, and automotive-qualified thermal performance.
Supply support for LT3491ESC8#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 product support, documentation, and manufacturing continuity for the LT3491 family.
The LT3491 belongs to Linear's high-efficiency LED driver product line, engineered specifically for portable backlighting and flash applications demanding small size, high integration, and robust fault protection.
FAQ
What is the maximum number of white LEDs the LT3491ESC8#TRMPBF can drive in series?
The LT3491ESC8#TRMPBF is specified to drive up to six white LEDs in series from a 3V supply, assuming typical forward voltage of 3.2V per LED (19.2V total). With its 27V open-LED protection clamp and 32V absolute max LED pin rating, it supports configurations up to six LEDs even under worst-case Vf drift and temperature variation. The LT3491ESC8#TRMPBF datasheet confirms this capability in both front-page description and Typical Application Circuits TA01a through TA06b.
Does the LT3491ESC8#TRMPBF require an external Schottky diode?
No, the LT3491ESC8#TRMPBF integrates a Schottky diode internally-confirmed in the Features section ("Internal Schottky Diode"), Absolute Maximum Ratings (Schottky Forward Drop ≤0.8V @ 100mA), and Block Diagram (Figure 1). This eliminates the need for external diode selection, layout, thermal design, and BOM management. The LT3491ESC8#TRMPBF CAP pin connects directly to the internal Schottky cathode, and SW pin serves as the anode node.
What is the function of the CTRL pin on the LT3491ESC8#TRMPBF?
The CTRL pin on the LT3491ESC8#TRMPBF serves dual functions: analog dimming control and shutdown enable. When pulled below 50mV, the IC shuts down with <10µA quiescent current. Between 100mV and 1.5V, LED current scales linearly from 0 to full value (ILED = 200mV/RSENSE). Above 1.5V, current remains at maximum. This single-pin interface simplifies system-level brightness control using DAC outputs, filtered PWM, or direct logic signals-verified in Electrical Characteristics Table and Figure G15.
Can the LT3491ESC8#TRMPBF operate from a 2.5V input supply?
Yes, the LT3491ESC8#TRMPBF has a minimum operating voltage of 2.5V, explicitly stated in Absolute Maximum Ratings and Electrical Characteristics tables. It successfully drives 3–4 white LEDs from 2.5V input in low-voltage applications such as two-AA-cell devices, as demonstrated in Application Circuit Figure F10 and Typical Performance Curve TA04b. Efficiency remains >65% at 2.5V input with 3 LEDs, per TA04b data.
What package type does the LT3491ESC8#TRMPBF use, and what are its thermal characteristics?
The LT3491ESC8#TRMPBF uses the 8-lead plastic SC70 (SC8) package with exposed pad, as confirmed by Order Information table and Package Description drawing #05-08-1639. Its thermal resistance is θJA = 270°C/W (JEDEC-standard test board), and the exposed pad must be soldered to PCB ground for rated performance. This differs from the DFN variant (LT3491EDC), which has θJA = 102°C/W but requires different layout and footprint.
LT3491ESC8#TRMPBF Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- -
- Package/Case:
- 8-VFSOP (0.049", 1.25mm Width)
- 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:
- -
- Current - Output / Channel:
- 350mA (Switch)
- Frequency:
- 2.3MHz
- Dimming:
- PWM
- Applications:
- Backlight
- Operating Temperature:
- -40°C ~ 85°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- SC-70-8
LT3491ESC8#TRMPBF FAQ
1.How can I place an order for LT3491ESC8#TRMPBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LT3491ESC8#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 LT3491ESC8#TRMPBF reliable?
The price and inventory of LT3491ESC8#TRMPBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LT3491ESC8#TRMPBF is usually 5 days.
3.What payment methods are accepted for LT3491ESC8#TRMPBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LT3491ESC8#TRMPBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LT3491ESC8#TRMPBF?
LT3491ESC8#TRMPBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LT3491ESC8#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 LT3491ESC8#TRMPBF?
For technical support, including LT3491ESC8#TRMPBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LT3491ESC8#TRMPBF requirements.
6.How does Aetrix verify that LT3491ESC8#TRMPBF is sourced from the original manufacturer or authorized distributors?
All LT3491ESC8#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 LT3491ESC8#TRMPBF meets industry standards.
7.What is the process for return or replacement of LT3491ESC8#TRMPBF?
All LT3491ESC8#TRMPBF units undergo pre-shipment inspection (PSI). If there is an issue with LT3491ESC8#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 LT3491ESC8#TRMPBF part is unused and in its original packaging.
Return procedure for LT3491ESC8#TRMPBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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