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Analog Devices Inc. LT3518EUF#PBF
- Part No.:
- LT3518EUF#PBF
- Manufacturer:
- Analog Devices Inc.
- Category:
- LED Drivers
- Package:
- 16-WQFN Exposed Pad
- Datasheet:
-
LT3518EUF#PBF.pdf
- Description:
- IC LED DRVR RGLTR PWM 2.3A 16QFN
- Quantity:
- Payment:
- Shipping:
Inventory:2,904
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Product details
Overview
LT3518EUF#PBF from Analog Devices is a constant-frequency current-mode DC/DC LED driver IC with an integrated 2.3A, 45V internal 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.
For engineers reviewing the LT3518EUF#PBF datasheet, LT3518EUF#PBF pinout, LT3518EUF#PBF application, or LT3518EUF#PBF equivalent, key selection criteria include its 250kHz–2.5MHz adjustable switching frequency, open-LED protection, PMOS gate driver for LED disconnect, and operation across 3V–30V input with transient tolerance to 40V.
Technical Context
The LT3518EUF#PBF implements dual-loop regulation-combining a voltage feedback loop (FB pin, 1.01V threshold) and a current sense loop (ISP/ISN, 100mV threshold)-to seamlessly transition between constant-current and constant-voltage modes. Its current-mode architecture uses a stabilizing ramp and peak switch current control determined by VCTRL or internal 100mV reference.
Switching frequency is set either by an external RT resistor (250kHz–2.5MHz) or synchronized to an external clock via SYNC pin, with built-in 20% frequency margin requirement. The TG output drives an external PMOS for LED string disconnect during PWM low periods, reducing output capacitor discharge and improving dimming transient recovery.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Switch Current Limit | 2.3A typical; sets maximum inductor/LED current capability without external current-limiting components. |
| Input Voltage Range | 3V to 30V continuous, 40V transient; supports wide automotive and industrial supply rails. |
| Current Sense Threshold | 100mV at ISP–ISN; enables accurate, low-loss LED current regulation with minimal power dissipation in sense resistor. |
| Dimming Ratio | 3000:1 PWM + 10:1 analog (CTRL); achieves high-fidelity grayscale control in display backlight systems. |
| Switching Frequency Range | 250kHz to 2.5MHz; allows trade-off between efficiency (lower fSW) and component size (higher fSW). |
| Operating Junction Temp | –40°C to 125°C; qualified for extended industrial and automotive ambient conditions. |
| Shutdown Current | <1µA; minimizes battery drain in always-on or low-power standby applications. |
Pinout & Package
The LT3518EUF#PBF 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/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| SW | Power Switch Output | Drives external inductor/diode; high di/dt node requiring minimized trace area to reduce EMI. |
| VIN | Main Input Supply | Accepts 3V–30V input; requires local 2.2µF ceramic bypass 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. |
| PWM | Digital Dimming Input | Active-low signal enabling 3000:1 PWM dimming; internally pulled down with 50kΩ resistor. |
| CTRL | Analog Current Setpoint | Sets LED current threshold from 0–100mV (0–1V input); clamped at 100mV above 1V for full-scale operation. |
| ISP / ISN | High-Side Current Sense | Differential inputs for 100mV sense resistor; rail-to-rail operation supports wide LED string voltage range. |
| TG | PMOS Gate Driver Output | Inverted PWM output driving external PMOS; includes 7V clamp to protect gate oxide when VISP up to 45V. |
| FB | Voltage Feedback Input | Regulates output voltage to 1.01V threshold; used for overvoltage protection and CV mode in boost configurations. |
| RT | Frequency Adjustment | Resistor-to-GND sets oscillator frequency; must not be left floating or capacitively loaded. |
| SYNC | External Clock Input | Accepts external clock for synchronization; RT resistor must be selected for 20% lower free-running frequency. |
Key Features
| Feature | Design Value |
|---|---|
| True Color PWM™ Dimming | 3000:1 ratio preserves color fidelity in LCD/OLED backlights by eliminating current ripple-induced hue shift. |
| Integrated 2.3A/45V Switch | Eliminates need for external MOSFET in most medium-power LED drivers, reducing BOM count and layout complexity. |
| Open LED Protection | Automatic shutdown when ISP–ISN voltage exceeds threshold, preventing overvoltage damage to LED string or IC. |
| PMOS LED Disconnect Driver | TG output enables fast, low-loss LED string isolation during PWM off-time, minimizing output capacitor discharge. |
| Adjustable Frequency (250kHz–2.5MHz) | Enables optimization of magnetic and capacitive components for size, cost, or EMI compliance per application. |
Applications
| Display Backlighting | Automotive Lighting |
|---|---|
Use Scenario: Driving white LED strings in LCD monitors, tablets, and medical displays requiring uniform brightness and flicker-free dimming. IC Role / Device Role / Timing Role: Constant-current LED driver operating in boost mode with 3000:1 PWM dimming and open-LED fault detection. Use Value: Enables high-contrast, low-flicker imaging with no color shift across dimming range due to True Color PWM™ architecture. | Use Scenario: Powering interior dome lights, map lights, and instrument cluster illumination in 12V/24V vehicle systems. IC Role / Device Role / Timing Role: Buck-mode LED driver with 3V–30V input range, transient tolerance to 40V, and –40°C to 125°C operation. Use Value: Ensures reliable startup and operation during cold cranking (≥3V) and load dump events (≤40V transients) without external protection. |
| Illumination Systems | Industrial Scanners |
Use Scenario: Controlling high-brightness LED arrays in architectural lighting, signage, and machine vision illuminators. IC Role / Device Role / Timing Role: Buck-boost LED driver supporting variable input (8V–16V) and stable current delivery despite LED Vf drift with temperature. Use Value: Maintains consistent lumen output across ambient temperature swings using dual-loop CC/CV regulation and CTRL-based thermal compensation. | Use Scenario: Pulsed LED illumination in barcode scanners and optical encoders requiring precise timing and rapid on/off transitions. IC Role / Device Role / Timing Role: Synchronized LED driver with SYNC input locked to system clock and TG-driven PMOS disconnect for sub-microsecond turn-off. Use Value: Achieves clean, jitter-free LED pulses with <200ns gate delays and no residual current leakage during off-state, critical for decoding accuracy. |
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, fixed 500kHz frequency, no integrated PWM dimming control; requires external PWM generator. | Better suited for high-current (>2A), fixed-frequency industrial lighting where analog dimming suffices. | Select LTC3783EFE#PBF when higher peak current and simplified frequency control outweigh need for integrated 3000:1 PWM. |
| LM3409QMH/NOPB | Lower 1.25A switch current, 40V max switch rating, no TG output or open-LED protection; automotive AEC-Q100 qualified. | Targeted at cost-sensitive automotive exterior lighting where AEC-Q100 compliance is mandatory and current demand ≤1.25A. | Choose LM3409QMH/NOPB only for AEC-Q100-compliant designs under 1.25A with no requirement for PMOS disconnect or open-LED fault response. |
Compared with LTC3783EFE#PBF and LM3409QMH/NOPB, the LT3518EUF#PBF uniquely integrates 3000:1 PWM dimming, TG-driven LED disconnect, and open-LED protection in a single 4mm × 4mm QFN-enabling compact, high-fidelity backlight solutions without external timing or fault-handling circuitry.
Availability
LT3518EUF#PBF is available at Aetrix Electronics and suitable for display backlighting, automotive lighting, and industrial illumination systems requiring stable component supply, long-term lifecycle support, and guaranteed parametric performance across –40°C to 125°C.
Supply support for LT3518EUF#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 LT3518EUF#PBF belongs to Linear Technology's precision LED driver product line, designed specifically for high-dynamic-range, color-critical illumination in displays and automotive systems where reliability, dimming fidelity, and fault robustness are essential.
FAQ
What is the maximum continuous input voltage rating for the LT3518EUF#PBF?
The LT3518EUF#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 automotive load-dump environments. Absolute maximum rating for VIN is 40V-exceeding this risks permanent device damage per datasheet Absolute Maximum Ratings.
Does the LT3518EUF#PBF support both constant-current and constant-voltage regulation modes?
Yes, the LT3518EUF#PBF implements dual-loop regulation: the current sense loop (ISP/ISN) enforces constant-current mode, while the FB pin regulates output voltage to 1.01V in constant-voltage mode. Whichever loop demands lower output current takes precedence, enabling seamless auto-transition between modes during LED Vf drift or open-circuit faults.
How is the switching frequency set on the LT3518EUF#PBF, and what is the valid range?
The LT3518EUF#PBF switching frequency is set via a resistor from RT to GND, supporting 250kHz to 2.5MHz. For example, a 16.9kΩ resistor yields ~1MHz. Alternatively, the SYNC pin accepts an external clock; the RT resistor must then be selected to produce a free-running frequency 20% slower than the SYNC signal to ensure reliable synchronization.
What is the function of the TG pin on the LT3518EUF#PBF, and how is it used?
The TG pin on the LT3518EUF#PBF is a top-gate driver output that provides an inverted PWM signal to drive an external PMOS transistor between VISP and the LED anode. It includes a 7V clamp to protect the PMOS gate when VISP reaches up to 45V. This enables fast LED string disconnect during PWM low periods, preserving output capacitor charge and improving dimming transient response.
Can the LT3518EUF#PBF operate in buck, boost, and buck-boost configurations?
Yes, the LT3518EUF#PBF is explicitly designed to operate in all three topologies. Its flexible feedback architecture-using ISP/ISN for current sensing and FB for voltage monitoring-allows implementation as a buck driver (e.g., 24V input → 12V LED string), boost driver (e.g., 5V input → 36V LED string), or buck-boost driver (e.g., 8–16V input → 24V LED string), as validated in multiple typical application circuits in the datasheet.
LT3518EUF#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)
LT3518EUF#PBF FAQ
1.How can I place an order for LT3518EUF#PBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LT3518EUF#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 LT3518EUF#PBF reliable?
The price and inventory of LT3518EUF#PBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LT3518EUF#PBF is usually 5 days.
3.What payment methods are accepted for LT3518EUF#PBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LT3518EUF#PBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LT3518EUF#PBF?
LT3518EUF#PBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LT3518EUF#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 LT3518EUF#PBF?
For technical support, including LT3518EUF#PBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LT3518EUF#PBF requirements.
6.How does Aetrix verify that LT3518EUF#PBF is sourced from the original manufacturer or authorized distributors?
All LT3518EUF#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 LT3518EUF#PBF meets industry standards.
7.What is the process for return or replacement of LT3518EUF#PBF?
All LT3518EUF#PBF units undergo pre-shipment inspection (PSI). If there is an issue with LT3518EUF#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 LT3518EUF#PBF part is unused and in its original packaging.
Return procedure for LT3518EUF#PBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
LT3518EUF#PBF Tags
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BCR402RE6327HTSA1
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BCR430UXTSA2
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BCR420UE6433HTMA1
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LYT1604D-TL
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CL2N8-G
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BCR420UW6-7
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