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Analog Devices Inc. LT3518IUF#PBF
- Part No.:
- LT3518IUF#PBF
- Manufacturer:
- Analog Devices Inc.
- Category:
- LED Drivers
- Package:
- 16-WQFN Exposed Pad
- Datasheet:
-
LT3518IUF#PBF.pdf
- Description:
- IC LED DRVR RGLTR PWM 2.3A 16QFN
- Quantity:
- Payment:
- Shipping:
Inventory:926
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Product details
Overview
LT3518IUF#PBF from Analog Devices is a constant-frequency current-mode DC/DC LED driver IC with an integrated 2.3A/45V N-channel power switch, supporting boost, buck, and buck-boost topologies. It delivers precise constant-current regulation via 100mV high-side current sensing and enables 3000:1 true-color PWM dimming for high-fidelity display backlighting in automotive and avionic systems.
For engineers reviewing the LT3518IUF#PBF datasheet, LT3518IUF#PBF pinout, LT3518IUF#PBF application, or LT3518IUF#PBF equivalent, key selection criteria include its –40°C to 125°C operating junction temperature range, 250kHz–2.5MHz adjustable switching frequency, open-LED protection, and gate driver for PMOS LED disconnect-critical for robust illumination and scanner designs.
Technical Context
The LT3518IUF#PBF implements dual-loop regulation: a voltage loop (FB pin, 1.01V threshold) for overvoltage protection and a current loop (ISP/ISN inputs, 100mV sense threshold) for LED current control. Its internal transconductance error amplifier (550µS) drives the VC pin to stabilize either loop, with automatic mode priority favoring the lower feedback demand.
Switching is synchronized via the SYNC pin or set by an external RT resistor (250kHz–2.5MHz); the 16-lead 4mm×4mm QFN package features an exposed thermal pad tied to GND, enabling efficient heat dissipation under continuous 2.3A switch operation at up to 30V input.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Switch Current Limit | 2.3A typical; supports high-brightness LED strings without external MOSFETs in buck or boost configurations. |
| Input Voltage Range | 3V to 30V continuous; withstands 40V transients-suitable for 12V/24V automotive rails with load-dump immunity. |
| Current Sense Threshold | 100mV ±3mV; enables accurate LED current regulation with low-power, high-precision sense resistors. |
| Dimming Ratio | 3000:1 true-color PWM; achieved via dedicated PWM pin with fast recovery and stored VC state-preserves color fidelity in displays. |
| Operating Temperature | –40°C to +125°C junction; qualified for industrial and automotive lighting environments per LT3518I grade. |
| Package | 16-lead 4mm × 4mm QFN (UF); exposed pad soldered to PCB ground plane for thermal management and EMI reduction. |
| Shutdown Current | <1µA; enables ultra-low-power standby in battery-powered illumination systems. |
Pinout & Package
The LT3518IUF#PBF is housed in a 16-lead plastic QFN package (4mm × 4mm) with an exposed thermal pad (Pin 17) that must be soldered directly to the PCB ground plane for thermal and electrical integrity.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| SW | Power Switch Output | Drives external inductor/diode; requires minimal trace area to reduce EMI and switching losses. |
| VIN | Main Input Supply | Accepts 3V–30V; must be bypassed locally with ≥1µF ceramic capacitor for stable operation. |
| SHDN | Enable/Disable Control | Logic-high (>1.2V) enables IC; logic-low (<0.45V) disables with <1µA quiescent current. |
| PWM | Digital Dimming Input | Directly controls LED current on/off; supports 3000:1 dimming ratio with stored VC state for fast recovery. |
| CTRL | Analog Dimming Input | Sets current sense threshold (0–1V → 0–100mV); provides 10:1 analog dimming when used with PWM. |
| ISP / ISN | High-Side Current Sense Inputs | Differential pair measuring voltage across external sense resistor; rail-to-rail operation supports wide LED Vf ranges. |
| TG | Top Gate Driver Output | Drives external PMOS for LED disconnect; clamped to VISP – 7V for safe gate drive in buck/buck-boost modes. |
| FB | Voltage Feedback Input | Regulates output voltage to 1.01V; triggers open-LED protection if voltage exceeds threshold. |
| RT | Frequency Adjustment | Resistor-to-GND sets switching frequency (250kHz–2.5MHz); required for SYNC synchronization. |
| SYNC | External Clock Input | Accepts external clock; RT must be configured for 20% lower free-running frequency for reliable sync lock. |
| VC | Error Amplifier Output | Compensation node for loop stability; external RC network adjusts bandwidth and transient response. |
| VREF | 2.0V Reference Output | Stable 2.0V ±20mV reference; supplies up to 100µA for CTRL bias or external circuitry. |
| SS | Soft-Start Control | Capacitor-to-GND controls startup ramp rate; prevents inrush current and output overshoot. |
| TGEN | PMOS Driver Enable | Logic-high enables TG output; internal 40kΩ pull-down allows default disable when unconnected. |
| GND | Ground Reference | Exposed pad (Pin 17) is sole GND terminal; must be soldered to PCB ground plane for thermal and electrical performance. |
Key Features
| Feature | Design Value |
|---|---|
| True Color PWM™ Dimming | 3000:1 ratio with stored VC state ensures zero color shift and sub-µs recovery during PWM transitions. |
| Integrated 2.3A/45V Switch | Eliminates need for external high-current MOSFET in most LED driver applications up to 30W. |
| Multi-Topology Operation | Native support for boost, buck, and buck-boost configurations simplifies design reuse across varied input/output requirements. |
| Open LED Protection | Automatic shutdown when FB > 1.01V prevents overvoltage damage to LEDs and downstream circuitry. |
| Adjustable Frequency (250kHz–2.5MHz) | Enables optimization of efficiency (low fSW) or solution size (high fSW) without changing topology or components. |
| PMOS Gate Driver (TG) | Provides controlled LED string disconnect during PWM off-time, preventing output capacitor discharge and improving dimming fidelity. |
Applications
| Automotive Headlight Modules | Avionic Display Backlighting |
|---|---|
Use Scenario: High-reliability LED driver for adaptive front-lighting systems (AFS) in passenger vehicles, operating from 9V–16V battery with load-dump tolerance. IC Role / Device Role / Timing Role: Constant-current LED driver with open-LED fault detection and 3000:1 PWM dimming for dynamic beam shaping. Use Value: Enables precise luminance control across temperature extremes (–40°C to +125°C), meeting AEC-Q100 stress test requirements for automotive electronics. | Use Scenario: Backlight power supply for cockpit LCDs in commercial aircraft, requiring EMI compliance and fail-safe operation. IC Role / Device Role / Timing Role: Boost-mode LED driver with SYNC input for system-level clock alignment and soft-start for inrush limiting. Use Value: Reduces electromagnetic emissions via controlled SW node layout and synchronized switching, satisfying DO-160 Section 21 Category D radiated emissions limits. |
| Industrial Scanner Illumination | Medical Imaging Light Engines |
Use Scenario: Pulsed LED source in high-speed barcode scanners, demanding microsecond-level dimming response and consistent intensity. IC Role / Device Role / Timing Role: Buck-boost LED driver with 2.3A switch and 100mV current sense for stable current delivery despite varying LED forward voltage. Use Value: Delivers repeatable light pulse amplitude and timing across 10,000+ cycles, supporting ISO/IEC 15416 verification standards. | Use Scenario: White LED illumination for endoscopic and dermatological imaging devices, requiring flicker-free, color-accurate output. IC Role / Device Role / Timing Role: Constant-current regulator with dual-loop control (voltage + current) and PMOS disconnect for zero-current hold during image capture. Use Value: Eliminates temporal artifacts in captured images by ensuring no LED leakage current during exposure windows. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar LED driver applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LTC3783EFE#PBF | Higher 4A switch current, 60V rating; no integrated current sense amplifier; requires external sense amp and compensation. | Targeted at higher-power (>50W) LED arrays; lacks native 3000:1 PWM dimming and open-LED protection. | Select when driving multi-string high-power LEDs where external control flexibility outweighs integration benefits. |
| LM3409QMH/NOPB | 2.5A/75V switch; fixed 100mV sense; no voltage loop or FB pin; only constant-current operation. | Designed exclusively for boost LED drivers; no buck/buck-boost capability or dual-loop regulation. | Choose for cost-sensitive, single-topology boost applications where constant-voltage regulation is unnecessary. |
Compared with LTC3783EFE#PBF and LM3409QMH/NOPB, the LT3518IUF#PBF uniquely integrates dual-loop regulation, 3000:1 PWM dimming, and multi-topology support in a thermally optimized QFN package-making it optimal for compact, high-fidelity illumination systems requiring both reliability and design flexibility.
Availability
LT3518IUF#PBF is available at Aetrix Electronics and suitable for automotive headlight modules, avionic display backlighting, and industrial scanner illumination requiring stable component supply across extended temperature ranges and long production lifecycles.
Supply support for LT3518IUF#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 (now part of Analog Devices, Inc. following merger with Linear Technology) is a global leader in high-performance analog, mixed-signal, and power management semiconductors.
The LT3518IUF#PBF belongs to Linear Technology's LED driver product line, engineered specifically for high-efficiency, high-dimming-ratio illumination systems in automotive, aerospace, and industrial applications where precision current regulation and robust fault protection are mandatory.
FAQ
What is the maximum continuous input voltage rating for the LT3518IUF#PBF?
The LT3518IUF#PBF supports continuous operation up to 30V on the VIN pin. It tolerates nonrepetitive 40V transients for up to one second, making it suitable for 24V automotive systems with load-dump events. Absolute maximum ratings specify 40V for VIN, SHDN, PWM, and TGEN pins under transient conditions only.
Does the LT3518IUF#PBF support buck, boost, and buck-boost topologies natively?
Yes, the LT3518IUF#PBF is explicitly designed to operate in all three topologies without external reconfiguration. Its internal architecture-including the ISP/ISN current sense inputs, TG driver, and FB voltage feedback-enables seamless transition between constant-current and constant-voltage regulation modes across boost, buck, and buck-boost configurations.
How does the LT3518IUF#PBF achieve 3000:1 PWM dimming ratio?
The LT3518IUF#PBF achieves 3000:1 true-color PWM dimming by combining fast PWM pin response (<3µs minimum pulse width at 2MHz switching), stored VC node state during PWM off-time, and external PMOS LED disconnect via the TG pin. This preserves LED current accuracy and eliminates color shift across the full dimming range.
What is the function of the TGEN pin on the LT3518IUF#PBF?
The TGEN pin on the LT3518IUF#PBF enables or disables the internal PMOS gate driver (TG output). When pulled high (>1.5V), it activates the TG pin to drive an external PMOS transistor for LED string disconnect during PWM off-cycles-preventing output capacitor discharge and improving dimming fidelity. An internal 40kΩ pull-down ensures safe default disable.
Is the LT3518IUF#PBF RoHS-compliant and lead-free?
Yes, the LT3518IUF#PBF carries the #PBF suffix, indicating it is lead-free and RoHS-compliant per Analog Devices' standard specifications. The device uses 100% matte tin lead finish and meets JEDEC J-STD-020 moisture sensitivity level 3 (MSL3) for surface-mount assembly.
LT3518IUF#PBF Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- -
- Package/Case:
- 16-WQFN Exposed Pad
- Packaging:
- Tube
- Product Status:
- Active
- Type:
- DC DC Regulator
- Topology:
- Step-Down (Buck), Step-Up (Boost)
- Internal Switch(s):
- Yes
- Number of Outputs:
- 1
- Voltage - Supply (Min):
- 3V
- Voltage - Supply (Max):
- 30V
- Voltage - Output:
- -
- Current - Output / Channel:
- 2.3A (Switch)
- Frequency:
- 250kHz ~ 2.5MHz
- Dimming:
- Analog, PWM
- Applications:
- Backlight
- Operating Temperature:
- -40°C ~ 125°C (TJ)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 16-QFN (4x4)
LT3518IUF#PBF FAQ
1.How can I place an order for LT3518IUF#PBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LT3518IUF#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 LT3518IUF#PBF reliable?
The price and inventory of LT3518IUF#PBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LT3518IUF#PBF is usually 5 days.
3.What payment methods are accepted for LT3518IUF#PBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LT3518IUF#PBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LT3518IUF#PBF?
LT3518IUF#PBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LT3518IUF#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 LT3518IUF#PBF?
For technical support, including LT3518IUF#PBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LT3518IUF#PBF requirements.
6.How does Aetrix verify that LT3518IUF#PBF is sourced from the original manufacturer or authorized distributors?
All LT3518IUF#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 LT3518IUF#PBF meets industry standards.
7.What is the process for return or replacement of LT3518IUF#PBF?
All LT3518IUF#PBF units undergo pre-shipment inspection (PSI). If there is an issue with LT3518IUF#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 LT3518IUF#PBF part is unused and in its original packaging.
Return procedure for LT3518IUF#PBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
LT3518IUF#PBF Tags
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