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Analog Devices Inc. LT3491ESC8#TRPBF
- Part No.:
- LT3491ESC8#TRPBF
- Manufacturer:
- Analog Devices Inc.
- Category:
- LED Drivers
- Package:
- 8-VFSOP (0.049", 1.25mm Width)
- Datasheet:
-
LT3491ESC8#TRPBF.pdf
- Description:
- IC LED DRV RGLTR PWM SC70-8
- Quantity:
- Payment:
- Shipping:
Inventory:4,074
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Product details
Overview
LT3491ESC8#TRPBF 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 single Li-Ion cell. It integrates a Schottky diode, features high-side current sensing for "one-wire" LED string connection, 2.3MHz switching, ±5% reference accuracy, and 27V open-LED protection. It targets compact portable backlighting in digital cameras and GPS receivers.
For engineers reviewing the LT3491ESC8#TRPBF datasheet, LT3491ESC8#TRPBF pinout, LT3491ESC8#TRPBF application, or LT3491ESC8#TRPBF equivalent, key selection criteria include its 2.3MHz operation enabling ultra-small 10µH inductors, 200mV LED current sense voltage, SC70-8 package footprint, integrated Schottky, and true-color PWM dimming with 300:1 range - all critical for space-constrained, battery-powered LED driver designs.
Technical Context
The LT3491ESC8#TRPBF employs constant-frequency current-mode control with an internal 2.3MHz oscillator and ramp-compensated PWM comparator. Its high-side sense architecture eliminates the need for ground-referenced ballast resistors, allowing the LED cathode to float while maintaining precise current regulation via VCAP–VLED feedback.
Startup is controlled by the CTRL pin threshold (100mV turn-on, 50mV shutdown), and overvoltage protection clamps CAP at 27V during open-circuit conditions. The integrated Schottky diode supports up to 1A inrush current and enables minimal external component count - only one inductor, two 1µF ceramic capacitors, and one sense resistor are required.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| VIN Range | 2.5V to 12V - supports direct Li-Ion (2.7–4.2V), dual-AA (2–3.2V), or 3.3V logic rail input without pre-regulation. |
| Switching Frequency | 2.3MHz (typ) - enables use of tiny 10µH inductors and 1µF ceramic output capacitors, minimizing board area. |
| LED Current Sense Voltage | 200mV (±5%) - sets ILED = 200mV / RSENSE; enables accurate, resistor-programmed current from 5mA to 200mA. |
| Open-LED Protection | 27V clamp (typ) - prevents destructive overvoltage on CAP pin if LED string opens; reduces switching frequency to limit input current. |
| CTRL Pin Function | Single-pin dimming & shutdown - 0–1.5V analog control provides full LED current range; <50mV disables regulator. |
| Integrated Schottky | Forward drop ≤0.8V @ 100mA - eliminates external diode, reduces BOM count, and simplifies layout in SC70-8 package. |
| Package | 8-Lead SC70 (2.2mm × 1.35mm) - ultra-compact footprint ideal for thin mobile devices with strict height constraints (<1mm profile). |
Pinout & Package
LT3491ESC8#TRPBF is housed in an 8-lead plastic SC70 package (JEDEC MO-203 variation BA, EIAJ SC-70). The package features a small outline (2.2mm × 1.35mm × 1.0mm max height) and exposed die pad not present in SC70-8 - thermal performance relies on PCB copper area under pins 2–4 (GND) and pin 1 (SW) routing.
| 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 and parasitic ringing. |
| GND (Pins 2, 3, 4) | Ground return paths | All three pins must be tied directly to local ground plane; shared GND improves thermal dissipation and noise immunity. |
| VIN (Pin 5) | Input supply input | Accepts 2.5–12V; requires local 1µF ceramic bypass capacitor placed adjacent to pin. |
| CTRL (Pin 6) | Dimming & shutdown control | Analog input: 0–1.5V sets LED current; <50mV forces shutdown; must not float - tie to GND or control voltage source. |
| LED (Pin 7) | High-side current sense input | Connects to LED string anode and sense resistor; enables "one-wire" LED connection by floating cathode side. |
| CAP (Pin 8) | Boost output / Schottky cathode | Drives LED string cathode; connects to output capacitor and internal Schottky anode; clamped at 27V during open-LED fault. |
Key Features
| Feature | Design Value |
|---|---|
| Integrated Schottky diode | Eliminates external diode, saves ~1.5mm² board area, and removes solder joint reliability risk in portable assemblies. |
| High-side LED current sense | Enables LED string cathode to connect anywhere (e.g., to system ground), simplifying flex cable routing and reducing interconnect layers. |
| 2.3MHz fixed-frequency operation | Permits use of 10µH inductors <2.5mm² footprint and 1µF X5R/X7R ceramics - cuts total solution size by >40% vs. 500kHz alternatives. |
| 300:1 true-color PWM dimming | Maintains consistent LED chromaticity across full brightness range by avoiding analog current modulation below 1.5V CTRL threshold. |
| 27V open-LED protection | Prevents CAP overvoltage damage during LED disconnection or failure; automatically throttles switching to limit input current draw. |
| Single-pin CTRL interface | Reduces system GPIO count - one microcontroller pin handles both enable/disable and fine-grained brightness control. |
Applications
| Digital Camera Backlight | GPS Receiver Display |
|---|---|
Use Scenario: Driving four white LEDs for high-brightness LCD backlight in sub-15mm-thick handheld GPS units with Li-Ion power. IC Role / Device Role / Timing Role: Boost converter with integrated Schottky and high-side sensing, delivering regulated 20mA per LED from 3.6V nominal input. Use Value: Enables single-layer flex PCB design with no external diode or ballast resistors, meeting 85°C ambient and 100,000-hour MTBF requirements. |
Use Scenario: Powering dual-row white LED status indicators in automotive-grade GPS modules operating from 9–16V vehicle supply. IC Role / Device Role / Timing Role: Step-up LED driver accepting 12V input, regulating current to six-series LEDs using external 1Ω sense resistor. Use Value: 27V open-LED clamp protects against LED string failure in sealed enclosures; 2.3MHz switching avoids AM radio band interference. |
| MP3 Player OLED Display | Smartphone Front Camera Flash |
Use Scenario: Dimmable backlight for 1.5-inch OLED display in battery-powered MP3 players requiring flicker-free 200Hz PWM. IC Role / Device Role / Timing Role: Constant-current LED driver supporting 300:1 true-color PWM dimming via microcontroller-generated 200Hz signal on CTRL pin. Use Value: Maintains color point stability across entire brightness range; 1.5V CTRL threshold ensures full current at logic-high levels from 3.3V MCU. |
Use Scenario: Torch/flash dual-mode LED driver in smartphones, delivering 100mA (torch) or 200mA (flash) to single white LED from 3.6V Li-Ion. IC Role / Device Role / Timing Role: Programmable current source with fast transient response (<30µs settling), supporting rapid flash activation. Use Value: Single IC replaces discrete boost + MOSFET + op-amp solution; CTRL pin voltage scaling allows seamless mode transition without firmware reconfiguration. |
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, same 200mV sense, but uses DFN-8 (3mm × 2mm) - 33% larger footprint than SC70-8. | Higher frequency allows smaller inductors but increases EMI sensitivity; lacks 27V open-LED clamp (max VOUT = 34V, no active clamp). | Choose LT3465EDD#TRPBF only when higher efficiency at light load or compatibility with existing DFN-8 layout is required. |
| LT1937ES5#TRPBF | 1.2MHz operation, ThinSOT-5 package (same pinout as SC70-5), no integrated Schottky - requires external diode. | Lower switching frequency demands larger 22µH inductor; external diode adds 0.4V forward drop and layout complexity. | Choose LT1937ES5#TRPBF only for cost-sensitive designs where board area is less constrained and external diode sourcing is acceptable. |
Compared with LT3491ESC8#TRPBF, LT3465EDD#TRPBF trades SC70-8 compactness for higher frequency and slightly better light-load efficiency, while LT1937ES5#TRPBF sacrifices integration and board area to reduce unit cost - making LT3491ESC8#TRPBF optimal for ultra-thin, high-reliability portable backlighting where space and BOM count are primary constraints.
Availability
LT3491ESC8#TRPBF is available at Aetrix Electronics and suitable for digital camera backlighting, GPS receiver displays, and MP3 player OLED illumination requiring stable component supply, long-term lifecycle support, and guaranteed RoHS-compliant manufacturing.
Supply support for LT3491ESC8#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 full technical and supply chain continuity for legacy Linear products including the LT3491 family.
The LT3491 product line was engineered specifically for space-constrained, battery-powered white LED backlighting in portable consumer electronics - emphasizing ultra-small footprint, integrated power components, and robust fault protection.
FAQ
What is the maximum number of white LEDs the LT3491ESC8#TRPBF can drive in series?
The LT3491ESC8#TRPBF 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). This assumes typical forward voltage of 3.2V per LED at 20mA, resulting in ~19.2V total VF, well within the device's 27V open-LED clamp and 32V absolute max LED pin rating.
Does the LT3491ESC8#TRPBF require an external Schottky diode?
No, the LT3491ESC8#TRPBF integrates a Schottky diode internally, as explicitly stated in the "Features" section ("Internal Schottky Diode") and verified in the block diagram (Figure 1) and pin function description for CAP (Pin 8). This eliminates the need for an external diode and reduces bill-of-materials count and PCB area.
What is the minimum LED current achievable with the LT3491ESC8#TRPBF before pulse-skipping occurs?
The LT3491ESC8#TRPBF can regulate down to 2mA LED current without pulse-skipping using the standard application circuit (Figure F02), as documented in the "Minimum Output Current" section. Below 2mA, the device enters discontinuous conduction mode and begins skipping pulses, though average current remains regulated down to zero.
How does the high-side current sense architecture of the LT3491ESC8#TRPBF simplify PCB layout?
The high-side sense architecture allows the LED string cathode to connect directly to system ground - eliminating the need for a dedicated ground-return trace from the LED assembly. This simplifies flex cable routing in clamshell or slider phones and reduces layer count in multi-layer boards, as confirmed in the "Description" section's comparison to traditional grounded-sense drivers.
What is the recommended capacitor type and value for the CAP pin of the LT3491ESC8#TRPBF?
The datasheet specifies a 1µF ceramic capacitor for the CAP pin, and mandates X5R or X7R dielectrics due to their stable capacitance over temperature - unlike Y5V or Z5U types which suffer significant derating. Recommended part examples include Taiyo Yuden GMK316BJ105ML and GMK325BJ225ML, as cited in multiple application schematics (e.g., TA01a, F06).
LT3491ESC8#TRPBF 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#TRPBF FAQ
1.How can I place an order for LT3491ESC8#TRPBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LT3491ESC8#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 LT3491ESC8#TRPBF reliable?
The price and inventory of LT3491ESC8#TRPBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LT3491ESC8#TRPBF is usually 5 days.
3.What payment methods are accepted for LT3491ESC8#TRPBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LT3491ESC8#TRPBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LT3491ESC8#TRPBF?
LT3491ESC8#TRPBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LT3491ESC8#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 LT3491ESC8#TRPBF?
For technical support, including LT3491ESC8#TRPBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LT3491ESC8#TRPBF requirements.
6.How does Aetrix verify that LT3491ESC8#TRPBF is sourced from the original manufacturer or authorized distributors?
All LT3491ESC8#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 LT3491ESC8#TRPBF meets industry standards.
7.What is the process for return or replacement of LT3491ESC8#TRPBF?
All LT3491ESC8#TRPBF units undergo pre-shipment inspection (PSI). If there is an issue with LT3491ESC8#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 LT3491ESC8#TRPBF part is unused and in its original packaging.
Return procedure for LT3491ESC8#TRPBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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