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Analog Devices Inc. LT3518IUF#TRPBF
- Part No.:
- LT3518IUF#TRPBF
- Manufacturer:
- Analog Devices Inc.
- Category:
- LED Drivers
- Package:
- 16-WQFN Exposed Pad
- Datasheet:
-
LT3518IUF#TRPBF.pdf
- Description:
- IC LED DRVR RGLTR PWM 2.3A 16QFN
- Quantity:
- Payment:
- Shipping:
Inventory:1,060
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Product details
Overview
LT3518IUF#TRPBF from Analog Devices is a constant-frequency current-mode DC/DC LED driver IC with an internal 2.3A, 45V power switch, supporting boost, buck, and buck-boost topologies. It delivers precise constant-current regulation via 100mV high-side current sensing, enables 3000:1 true-color PWM dimming, and operates across 3V–30V input with transient tolerance to 40V - ideal for automotive display backlighting and industrial illumination systems.
For engineers reviewing the LT3518IUF#TRPBF datasheet, LT3518IUF#TRPBF pinout, LT3518IUF#TRPBF application, or LT3518IUF#TRPBF equivalent, key selection criteria include its dual-loop (voltage + current) regulation architecture, programmable 250kHz–2.5MHz switching frequency, integrated PMOS gate driver for LED disconnect, open-LED protection, and –40°C to 125°C industrial temperature grade in 4mm × 4mm QFN.
Technical Context
The LT3518IUF#TRPBF implements a dual-loop control system where the error amplifier selects between voltage feedback (FB pin, 1.01V threshold) and current feedback (ISP/ISN differential sense) to seamlessly transition between constant-voltage and constant-current modes. Its current-mode architecture uses a stabilizing ramp and peak-current limiting to ensure cycle-by-cycle stability across wide duty cycles.
Switching frequency is set either by an external RT resistor (250kHz–2.5MHz range) or synchronized to an external clock via SYNC pin, with internal logic ensuring turn-on occurs at a fixed delay after SYNC's rising edge. The TG pin provides inverted PWM output to drive an external PMOS for LED current path disconnection during dimming, reducing output capacitor discharge and improving transient recovery.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Internal Switch | 2.3A, 45V rated MOSFET - supports high-brightness LED strings up to ~70W in boost mode with minimal external components. |
| Current Sense Threshold | 100mV (±3mV) - enables accurate LED current regulation with low-power, low-thermal-drift sense resistors (e.g., 68mΩ for 1.47A). |
| Dimming Ratio | 3000:1 true-color PWM - achieved with minimum 3µs pulse width at 2MHz switching, preserving color fidelity in display backlighting. |
| Input Voltage Range | 3V to 30V continuous, 40V transient - accommodates 12V/24V automotive rails and industrial supplies with robust overvoltage immunity. |
| Operating Temperature | –40°C to +125°C junction - qualified for under-hood automotive lighting and industrial embedded systems without derating. |
| Shutdown Current | <1µA - enables ultra-low-power standby in battery-backed illumination or portable devices. |
| Package | 16-lead 4mm × 4mm QFN with exposed thermal pad - provides low θJA = 36°C/W for thermally constrained PCB layouts. |
Pinout & Package
LT3518IUF#TRPBF is housed in a 16-lead (4mm × 4mm) plastic QFN package with exposed thermal pad (Pin 17), which must be soldered to PCB ground for thermal and electrical integrity. Pin pitch is 0.5mm; package conforms to JEDEC MO-220WEED.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| SW | Power Switch Output | Drives external inductor/diode; requires minimized trace area to reduce EMI and switching losses. |
| VIN | Main Input Supply | Accepts 3V–30V; must be bypassed with ≥1µF low-ESR ceramic capacitor placed adjacent to pin. |
| SHDN | Enable/Disable Control | Logic-high (≥1.2V) enables operation; logic-low (≤0.45V) disables switch and reduces quiescent current to <1µA. |
| FB | Voltage Feedback Input | Regulates output voltage to 1.01V threshold; used for overvoltage protection and CV mode in boost configurations. |
| VC | Error Amplifier Output | gm amplifier output (550µS); connects to RC compensation network to stabilize current/voltage loops. |
| CTRL | Analog Dimming Input | Sets current sense threshold from 0V to 1V; 0.1V yields 10% full-scale current (10:1 analog dimming). |
| PWM | Digital Dimming Input | Active-low signal disables main switch and forces TG high; enables 3000:1 PWM dimming with stored VC state. |
| TG | Top-Gate Driver Output | Inverted PWM output driving external PMOS; clamped to VISP – 7V for safe gate drive of high-side disconnect FET. |
| ISP / ISN | High-Side Current Sense Inputs | Differential inputs referenced to VISP; support rail-to-rail sensing with 300nA bias current and 0.03%/V line regulation. |
| TGEN | PMOS Gate Enable | Logic-high (≥1.5V) activates TG output; internal 40kΩ pull-down ensures safe default-off state. |
| RT | Frequency Set Input | Resistor-to-ground sets oscillator frequency; 16.9kΩ yields 1MHz; must not be left floating or capacitive-loaded. |
| SYNC | External Clock Input | Accepts 0.4V–1.5V logic-low/high; synchronizes switch turn-on to external clock rising edge with fixed delay. |
| SS | Soft-Start Control | Capacitor-to-ground controls startup ramp rate; 0.1µF yields smooth start with minimal inrush current. |
| VREF | 2.0V Reference Output | Stable 2.0V ±20mV reference (1.96–2.04V) sourcing up to 100µA; used to bias CTRL or external circuitry. |
| GND | Ground / Exposed Pad | Thermal and electrical ground; exposed pad (Pin 17) must be soldered to PCB ground plane with thermal vias. |
Key Features
| Feature | Design Value |
|---|---|
| Dual-loop regulation | Simultaneous FB (1.01V) and ISP/ISN (100mV) feedback paths enable automatic, seamless transition between constant-voltage and constant-current modes without external logic. |
| Integrated PMOS gate driver | TG output with 7V clamp and TGEN enable allows direct control of high-side LED disconnect switch, eliminating need for external level-shifting circuitry. |
| Open-LED protection | Monitors ISP/ISN differential voltage; disables switching if sense voltage exceeds threshold, preventing overvoltage damage to LEDs and output capacitors. |
| Programmable frequency & sync | RT resistor sets 250kHz–2.5MHz range; SYNC input accepts external clocks up to 2.5MHz with 20% slower RT setting for deterministic phase alignment. |
| Low-noise soft-start | SS pin accepts external capacitor to linearly ramp VC voltage, suppressing output overshoot and inrush current during startup without requiring external controllers. |
Applications
| Automotive Display Backlighting | Industrial Illumination Systems |
|---|---|
Use Scenario: Driving white LED arrays in TFT-LCD instrument clusters and center-stack displays in vehicles operating across –40°C to +105°C ambient. IC Role / Device Role / Timing Role: Constant-current LED driver with 3000:1 PWM dimming and open-LED fault detection, regulating brightness while maintaining color consistency. Use Value: Eliminates need for external current-sense amplifiers and dimming controllers; 40V transient tolerance protects against load-dump events per ISO 7637-2. | Use Scenario: Powering high-intensity LED fixtures in factory floor lighting, machine vision inspection, and hazardous-area illumination. IC Role / Device Role / Timing Role: Buck-boost LED driver delivering stable 300mA–1.5A output from variable 8V–32V industrial supplies with thermal foldback. Use Value: Single-chip solution supports wide input range and multiple topologies; exposed-pad QFN enables reliable thermal management in enclosed enclosures. |
| Avionic Cabin Lighting | Barcode Scanner Illumination |
Use Scenario: Controlling dimmable LED strips in aircraft passenger service units (PSUs) and reading lights, meeting DO-160 lightning-induced transient requirements. IC Role / Device Role / Timing Role: Boost-mode LED driver with 1.01V FB regulation and 100mV current sensing, enabling precise luminance control across 18V–32V aircraft bus voltages. Use Value: Integrated 45V switch and 40V transient rating simplify input protection design; low shutdown current extends battery backup runtime. | Use Scenario: Pulsed high-brightness illumination for CCD/CMOS image sensors in handheld and fixed-mount barcode scanners. IC Role / Device Role / Timing Role: Synchronized buck-mode LED driver with 2MHz switching and 3000:1 PWM dimming, timed to camera exposure windows. Use Value: SYNC pin aligns LED pulses with sensor integration time; fast transient recovery preserves consistent illumination intensity across rapid scan sequences. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar LED driver applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LTC3783EFE#TRPBF | Higher 4A switch current, 60V rating, but no integrated current sense amplifier; requires external 0.1Ω sense resistor and op-amp for current loop. | Targeted at higher-power (>50W) LED arrays; lacks 3000:1 PWM dimming and open-LED protection. | Select when >2.3A output or >45V input is required; expect added BOM cost and layout complexity for current sensing. |
| MAX16820ATP+T | 2.5A switch, 40V rating, 100mV sense, but only supports boost topology; no buck/buck-boost capability or TG driver. | Optimized for LCD backlight boost converters; lacks multi-topology flexibility and PMOS disconnect for deep dimming. | Choose for cost-sensitive boost-only designs where TG functionality and topology versatility are unnecessary. |
Compared with LTC3783EFE#TRPBF and MAX16820ATP+T, the LT3518IUF#TRPBF uniquely integrates dual-loop regulation, 3000:1 PWM dimming, and a PMOS gate driver in a single 4mm × 4mm QFN - reducing component count and PCB area for compact, multi-topology LED systems requiring industrial temperature reliability.
Availability
LT3518IUF#TRPBF is available at Aetrix Electronics and suitable for automotive display backlighting, industrial illumination systems, avionic cabin lighting, and barcode scanner illumination requiring stable component supply across extended temperature ranges and long production lifecycles.
Supply support for LT3518IUF#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) is a global leader in high-performance analog, mixed-signal, and power management semiconductors, serving precision instrumentation, industrial automation, and automotive markets.
The LT3518 belongs to Linear's high-efficiency LED driver product line, designed specifically for compact, thermally constrained LED lighting applications demanding wide input range, multi-topology flexibility, and high-fidelity dimming performance.
FAQ
What is the maximum continuous input voltage rating for the LT3518IUF#TRPBF?
The LT3518IUF#TRPBF has a maximum continuous input voltage rating of 30V at the VIN pin. It tolerates nonrepetitive 40V transients for up to one second, making it suitable for 24V automotive and industrial systems subject to load-dump conditions. Operation above 30V continuously risks exceeding absolute maximum ratings and must be avoided per datasheet Note 3.
How does the LT3518IUF#TRPBF achieve 3000:1 PWM dimming ratio?
The LT3518IUF#TRPBF achieves 3000:1 true-color PWM dimming by combining fast switching (up to 2.5MHz), stored VC node state during PWM low periods, and synchronized TG-driven PMOS LED disconnect. With a 2MHz switching frequency, the minimum 3µs pulse width yields a 9ms/3µs = 3000:1 ratio - verified in typical application TA04b and confirmed in Electrical Characteristics Table.
Can the LT3518IUF#TRPBF operate in buck, boost, and buck-boost topologies with the same pin configuration?
Yes, the LT3518IUF#TRPBF supports all three topologies using identical pin connections - only external component placement (inductor, diode, sense resistor, feedback divider) changes per configuration. Its dual-loop architecture automatically adapts: FB dominates in boost (CV), ISP/ISN dominates in buck (CC), and both interact in buck-boost to maintain regulation across input/output crossovers.
What is the function of the TG and TGEN pins on the LT3518IUF#TRPBF?
The TG pin is an inverted PWM output that drives the gate of an external PMOS transistor placed in series with the LED string; TGEN enables this function (≥1.5V). When active, TG pulls low during PWM high to turn on the PMOS, and goes high during PWM low to disconnect the LED current path - preventing output capacitor discharge and enabling faster dimming recovery in the LT3518IUF#TRPBF.
Is the LT3518IUF#TRPBF RoHS-compliant and lead-free?
Yes, the LT3518IUF#TRPBF is RoHS-compliant and features a lead-free finish, as indicated by the "#PBF" and "#TRPBF" suffixes in its orderable part number. Per Linear Technology's lead-free marking guide, the "PBF" designation confirms compliance with EU RoHS Directive 2011/65/EU and JEDEC JS-001 standards.
LT3518IUF#TRPBF Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- -
- Package/Case:
- 16-WQFN Exposed Pad
- Packaging:
- Tape & Reel (TR)
- 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#TRPBF FAQ
1.How can I place an order for LT3518IUF#TRPBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LT3518IUF#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 LT3518IUF#TRPBF reliable?
The price and inventory of LT3518IUF#TRPBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LT3518IUF#TRPBF is usually 5 days.
3.What payment methods are accepted for LT3518IUF#TRPBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LT3518IUF#TRPBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LT3518IUF#TRPBF?
LT3518IUF#TRPBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LT3518IUF#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 LT3518IUF#TRPBF?
For technical support, including LT3518IUF#TRPBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LT3518IUF#TRPBF requirements.
6.How does Aetrix verify that LT3518IUF#TRPBF is sourced from the original manufacturer or authorized distributors?
All LT3518IUF#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 LT3518IUF#TRPBF meets industry standards.
7.What is the process for return or replacement of LT3518IUF#TRPBF?
All LT3518IUF#TRPBF units undergo pre-shipment inspection (PSI). If there is an issue with LT3518IUF#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 LT3518IUF#TRPBF part is unused and in its original packaging.
Return procedure for LT3518IUF#TRPBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
LT3518IUF#TRPBF Tags
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