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Analog Devices Inc. LTC3490EDD#PBF
- Part No.:
- LTC3490EDD#PBF
- Manufacturer:
- Analog Devices Inc.
- Category:
- LED Drivers
- Package:
- 8-WFDFN Exposed Pad
- Datasheet:
-
LTC3490EDD#PBF.pdf
- Description:
- IC LED DRVR RGLTR DIM 350MA 8DFN
- Quantity:
- Payment:
- Shipping:
Inventory:227
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Product details
Overview
LTC3490EDD#PBF from Analog Devices (formerly Linear Technology) is a synchronous boost LED driver IC designed for single- or dual-cell NiMH/alkaline portable lighting. It delivers 350mA constant current with 2.8V–4V output compliance, 1.3MHz fixed-frequency operation, and <1mA quiescent current-enabling compact, high-efficiency 1W white LED flashlights.
For engineers reviewing the LTC3490EDD#PBF datasheet, LTC3490EDD#PBF pinout, LTC3490EDD#PBF application, or LTC3490EDD#PBF equivalent, key selection factors include its 1V–3.2V input range, analog dimming via CTRL/SHDN, open-LED voltage limiting to 4.7V, and thermal-enhanced 3mm × 3mm DFN package with exposed ground pad.
Technical Context
The LTC3490EDD#PBF integrates a 100mΩ NMOS switch and 130mΩ PMOS synchronous rectifier in a current-mode boost architecture. Its internal compensation eliminates external loop components, while the CELLs pin configures undervoltage lockout thresholds (0.85V/cell for 1-cell, 1.4V/cell for 2-cell mode).
Dimming is implemented via analog control: ILED = 500 × (VCTRL/VIN − 0.2) mA for VCTRL between 0.2×VIN and 0.9×VIN; outside that range, it clamps at 350mA or enters shutdown (<50µA IIN). LOBAT provides open-drain low-battery indication.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| LED Drive Current | 350mA typical, ±20mA over temperature - ensures stable 1W LED brightness without external sense resistor |
| Input Voltage Range | 1V to 3.2V - supports operation down to near-dead NiMH/alkaline cells, enabling extended runtime |
| Output Compliance | 2.8V to 4V - matches forward voltage of standard 1W white LEDs (e.g., Luxeon LXHL-BW02) |
| Switching Frequency | 1.3MHz typical - allows use of small 3.3µH inductor and 4.7µF ceramic capacitor |
| Efficiency | Up to 90% - achieved via synchronous rectification, minimizing heat in space-constrained flashlight designs |
| Shutdown Current | <50µA - preserves battery life during storage or standby |
| Open-LED Limit | 4.7V max - protects IC and downstream circuitry if LED disconnects or fails open |
Pinout & Package
Package: 8-lead 3mm × 3mm plastic DFN (DD) with exposed thermal pad (Pin 9), requiring solder connection to PCB ground for thermal and electrical performance.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| CELLS (1) | Logic input | Selects 1-cell (GND) or 2-cell (VIN) UVLO/detection thresholds - sets battery protection behavior |
| VIN (2) | Power input | Accepts 1V–3.2V battery input; powers internal circuitry and gate drivers |
| SW (3) | Switch node | Connects to external inductor; carries high di/dt switching current - requires short, wide trace |
| GND (4) | Ground reference | Analog and power ground; tied to exposed pad for thermal conduction |
| LED (5) | Constant-current output | Sinks regulated 350mA to LED anode; output voltage floats up to 4.7V limit |
| CAP (6) | Filter capacitor node | Connects 4.7µF low-ESR ceramic capacitor - stabilizes output and reduces ripple |
| LOBAT (7) | Open-drain flag | Asserts low when battery drops below 0.8V/cell (1-cell) or 1.8V (2-cell) - enables user alert |
| CTRL/SHDN (8) | Dimming & enable | Analog dimming input (0.2–0.9×VIN) or shutdown trigger (<0.2×VIN); no external pull-up needed |
| Exposed Pad (9) | Thermal/Ground | Mandatory solder connection to PCB ground plane - critical for thermal dissipation and noise immunity |
Key Features
| Feature | Design Value |
|---|---|
| Integrated Synchronous Rectification | 100mΩ NMOS + 130mΩ PMOS switches eliminate external Schottky loss - enables >90% efficiency at light loads |
| Single-Potentiometer Dimming | Current scales linearly with VCTRL/VIN, removing battery-voltage dependency - simplifies mechanical dimmer design |
| Programmable Low-Battery Detection | CELLS pin selects threshold per cell count - prevents deep discharge damage to NiMH/alkaline batteries |
| Internally Compensated Loop | No external compensation components required - reduces BOM count and layout sensitivity |
| Robust Open-LED Protection | Hard-clamped 4.7V output limit - avoids overvoltage stress on LED string or PCB traces |
Applications
| Rechargeable Flashlights | Portable Medical Lighting |
|---|---|
Use Scenario: Handheld LED flashlight powered by two AA alkaline cells with momentary ON/OFF and adjustable brightness. IC Role / Device Role / Timing Role: Constant-current boost driver regulating 350mA to white LED; CELLs pin set to VIN for 2-cell UVLO; CTRL/SHDN driven by potentiometer. Use Value: Delivers full 1W LED output down to 1.8V total battery voltage, then smoothly dims as cells deplete - extends usable runtime by 30% vs. fixed-output drivers. | Use Scenario: Battery-powered otoscope or headlamp used in field diagnostics where reliability and long shelf life are critical. IC Role / Device Role / Timing Role: Primary LED current source with LOBAT flag wired to microcontroller GPIO to trigger low-battery warning LED. Use Value: <50µA shutdown current preserves primary battery for >2 years in storage; 1V start-up ensures operation even after prolonged discharge. |
| Emergency Signage | Industrial Inspection Lights |
Use Scenario: Self-contained exit sign or hazard marker using NiMH rechargeable pack with automatic dimming on low battery. IC Role / Device Role / Timing Role: LED driver with LOBAT signal feeding comparator circuit that reduces ILED to 70mA when battery falls below threshold. Use Value: Maintains visibility for >8 hours at reduced brightness after main charge depletes - meets NFPA 101 emergency lighting duration requirements. | Use Scenario: Ruggedized handheld inspection lamp for factory floor use, powered by 2×AA NiMH with metal housing acting as heatsink. IC Role / Device Role / Timing Role: High-efficiency current source driving Luxeon red LED; exposed pad soldered to copper pour under IC for thermal management. Use Value: 90% efficiency minimizes self-heating in sealed enclosure; 3mm × 3mm DFN footprint enables compact, drop-resistant mechanical design. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar constant-current LED driver applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LTC3205 | Charge-pump topology; 2.8V–4.5V input; no inductor required; lower max output voltage (6V) | Best for multi-LED strings in space-constrained devices where inductor EMI is unacceptable | Choose LTC3205 only if inductor-free design and lower output compliance (≤6V) are acceptable trade-offs |
| LTC3402 | Synchronous boost regulator (not LED-specific); 0.85V–5V input; 2A output; requires external current-sense resistor | Suitable for custom LED current regulation with programmable setpoint, but adds component count and layout complexity | Choose LTC3402 only when flexible current programming (beyond 350mA) and wider input range outweigh BOM simplicity |
Compared with LTC3490EDD#PBF, LTC3205 eliminates magnetic components but sacrifices output compliance and efficiency above 3.5V; LTC3402 offers higher current headroom and broader input range but requires external sensing and compensation - neither is pin-compatible, and both increase design effort for basic 350mA flashlight applications.
Availability
LTC3490EDD#PBF is available at Aetrix Electronics and suitable for rechargeable flashlights, portable medical lighting, and industrial inspection tools requiring stable component supply, long-term manufacturability, and guaranteed lead-free compliance.
Supply support for LTC3490EDD#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 acquired Linear Technology in 2017 and maintains full product support, documentation, and manufacturing continuity for legacy Linear parts including the LTC3490 series.
The LTC3490 belongs to Linear's high-efficiency portable LED driver family, engineered specifically for battery-powered lighting where minimal external components, ultra-low quiescent current, and robust battery protection are mandatory.
FAQ
What is the minimum input voltage required for LTC3490EDD#PBF to start switching?
The LTC3490EDD#PBF has a minimum start-up voltage of 0.9V (typical) and 1.0V (max) per the datasheet. It can begin regulation with as little as 1V input, and once the LED voltage exceeds 2.3V, the device sustains operation even if VIN drops slightly below the start-up threshold. This enables reliable ignition from nearly depleted NiMH or alkaline cells - a key feature for flashlight applications where runtime extension is critical. The LTC3490EDD#PBF achieves this via an internal low-voltage start-up circuit independent of the main regulator loop.
Can LTC3490EDD#PBF drive red Luxeon LEDs without additional components?
No - red Luxeon LEDs have forward voltages as low as 2.31V, below the 2.5V minimum required for reliable LTC3490EDD#PBF internal circuitry operation. For non-dimming use, a 0.6Ω series resistor raises the effective load voltage; for dimming applications, a Schottky diode (e.g., MBRM120E) is recommended to maintain sufficient output voltage across the dimming range. These additions ensure stable regulation and prevent dropout during low-current operation. The LTC3490EDD#PBF itself does not integrate this functionality.
How does the CELLs pin affect undervoltage lockout behavior in LTC3490EDD#PBF?
The CELLs pin configures the LTC3490EDD#PBF for either 1-cell or 2-cell battery systems: tying it to GND sets UVLO at 0.7–0.9V/cell (1-cell mode), while tying it to VIN sets UVLO at 1.4–1.8V/cell (2-cell mode). This directly determines when the part shuts down to protect batteries from deep discharge. In 1-cell mode, LOBAT asserts at ~0.8V; in 2-cell mode, it asserts at ~1.8V. The LTC3490EDD#PBF uses this pin to scale both UVLO and low-battery detection thresholds - no external resistors or configuration registers are needed.
What is the purpose of the exposed pad on the LTC3490EDD#PBF DFN package?
The exposed pad (Pin 9) on the LTC3490EDD#PBF is electrically and thermally connected to GND. It must be soldered to a PCB copper pour tied to system ground to provide low-thermal-resistance heat dissipation (θJA = 43°C/W) and reduce junction temperature rise during continuous 350mA operation. Failure to solder this pad results in excessive die temperature, potential thermal shutdown, and reduced reliability. The LTC3490EDD#PBF datasheet explicitly states this pad "MUST BE SOLDERED TO PCB" - it is not optional for functional or safety-critical designs.
Does LTC3490EDD#PBF require external compensation components?
No - the LTC3490EDD#PBF features fully internal loop compensation, requiring only four external components for basic operation: an inductor (3.3µH), output capacitor (4.7µF), input bypass capacitor (optional), and pull-down resistor on CTRL/SHDN (optional for shutdown). This eliminates external compensation networks (e.g., RC filters or op-amp integrators) that complicate layout, increase cost, and degrade stability margin. The LTC3490EDD#PBF achieves this via optimized internal transconductance amplifier and frequency compensation - confirmed in the Functional Block Diagram and Applications Information sections of the datasheet.
LTC3490EDD#PBF Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- -
- Package/Case:
- 8-WFDFN Exposed Pad
- Packaging:
- Tube
- Product Status:
- Active
- Type:
- DC DC Regulator
- Topology:
- Step-Up (Boost)
- Internal Switch(s):
- Yes
- Number of Outputs:
- 1
- Voltage - Supply (Min):
- 1V
- Voltage - Supply (Max):
- 3.2V
- Voltage - Output:
- 2.8V ~ 4V
- Current - Output / Channel:
- 350mA
- Frequency:
- 1.3MHz
- Dimming:
- Analog
- Applications:
- -
- Operating Temperature:
- -40°C ~ 85°C (TA)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 8-DFN (3x3)
LTC3490EDD#PBF FAQ
1.How can I place an order for LTC3490EDD#PBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LTC3490EDD#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 LTC3490EDD#PBF reliable?
The price and inventory of LTC3490EDD#PBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LTC3490EDD#PBF is usually 5 days.
3.What payment methods are accepted for LTC3490EDD#PBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LTC3490EDD#PBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LTC3490EDD#PBF?
LTC3490EDD#PBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LTC3490EDD#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 LTC3490EDD#PBF?
For technical support, including LTC3490EDD#PBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LTC3490EDD#PBF requirements.
6.How does Aetrix verify that LTC3490EDD#PBF is sourced from the original manufacturer or authorized distributors?
All LTC3490EDD#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 LTC3490EDD#PBF meets industry standards.
7.What is the process for return or replacement of LTC3490EDD#PBF?
All LTC3490EDD#PBF units undergo pre-shipment inspection (PSI). If there is an issue with LTC3490EDD#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 LTC3490EDD#PBF part is unused and in its original packaging.
Return procedure for LTC3490EDD#PBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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