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Analog Devices Inc. LT3518IFE#PBF
- Part No.:
- LT3518IFE#PBF
- Manufacturer:
- Analog Devices Inc.
- Category:
- LED Drivers
- Package:
- 16-TSSOP (0.173", 4.40mm Width) Exposed Pad
- Datasheet:
-
LT3518IFE#PBF.pdf
- Description:
- IC LED DRV RGLTR PWM 16TSSOP
- Quantity:
- Payment:
- Shipping:
Inventory:1,289
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Product details
Overview
LT3518IFE#PBF 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 from 3V to 30V input with transient protection up to 40V-used in automotive lighting and display backlighting.
For engineers reviewing the LT3518IFE#PBF datasheet, LT3518IFE#PBF pinout, LT3518IFE#PBF application, or LT3518IFE#PBF equivalent, key selection criteria include its 2.3A switch rating, 100mV current sense threshold, 250kHz–2.5MHz adjustable switching frequency, open-LED protection, and dual dimming (PWM + CTRL analog) capability for high-fidelity LED control.
Technical Context
The LT3518IFE#PBF integrates a current-sense amplifier, transconductance error amplifier (550 µS), and dual-loop regulation (voltage feedback at FB pin, current feedback via ISP/ISN) to seamlessly transition between constant-current and constant-voltage modes. Its internal 2.3A/45V N-channel MOSFET switch supports peak currents up to 3.5A and features gate drive for external PMOS disconnect (TG output with 7V clamp).
Switching frequency is set by an external RT resistor (250kHz–2.5MHz) or synchronized to an external clock via SYNC pin (with 20% slower RT programming). The CTRL pin linearly adjusts current threshold from 0 to 100mV (0–1V input), while PWM pin enables full-cycle on/off control with stored VC state for fast recovery.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Switch Current Limit | 2.3A typical; enables driving high-brightness LED strings up to ~1.5A continuous in buck mode with margin. |
| Current Sense Threshold | 100mV nominal; allows accurate LED current setting with low-loss, high-precision sense resistors (e.g., 68mΩ for 1.47A). |
| Input Voltage Range | 3V to 30V continuous; supports 12V/24V automotive rails and industrial supplies, with 40V transient tolerance. |
| Dimming Ratio | 3000:1 via PWM pin; achieves flicker-free, high-fidelity color rendering in display backlighting without current droop. |
| Switching Frequency Range | 250kHz to 2.5MHz; permits optimization of inductor size (e.g., 4.3µH at 2MHz) vs. efficiency (e.g., 15µH at 1MHz). |
| FB Pin Threshold | 1.01V ±30mV; provides overvoltage protection for LED strings and enables precise output voltage setting in boost configurations. |
| Shutdown Current | <1µA; ensures minimal battery drain in always-on automotive or portable illumination systems. |
Pinout & Package
LT3518IFE#PBF is housed in a 16-lead plastic TSSOP package (FE grade), with exposed pad soldered to PCB ground for thermal management and EMI reduction. Pin 17 (exposed pad) is GND and must be connected.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| VIN | Input supply rail | Accepts 3V–30V DC; requires local 2.2µF ceramic bypass capacitor to suppress high di/dt noise. |
| SHDN | Enable/disable control | Logic-high ≥1.2V enables operation; ≤0.45V disables with <1µA quiescent current. |
| PWM | Digital dimming input | Active-low signal disables switching and saves VC state; enables 3000:1 dimming with aligned SYNC edge timing. |
| CTRL | Analog current adjustment | 0–1V input scales current sense threshold from 0 to 100mV; used for temperature compensation or fine-tuning. |
| ISP / ISN | High-side current sense inputs | Differential pair measuring voltage across external sense resistor; rail-to-rail operation supports wide LED Vf range. |
| TG | PMOS gate driver output | Drives external PMOS disconnect switch; clamped to VISP – 7V to protect gate oxide. |
| FB | Voltage feedback input | Regulates output to 1.01V; used for overvoltage protection and boost/buck-boost output voltage setting. |
| VC | Error amplifier output | gm = 550µS; connects to RC compensation network for loop stability in constant-current or constant-voltage mode. |
Key Features
| Feature | Design Value |
|---|---|
| True Color PWM™ dimming | 3000:1 ratio preserves LED chromaticity during dimming-critical for medical displays and avionics HUDs. |
| Open LED protection | Automatic shutdown when ISP/ISN detect no current flow-prevents overvoltage damage to LEDs and driver. |
| Adjustable frequency with SYNC | RT resistor sets base frequency; SYNC pin allows synchronization to system clock-reduces EMI in multi-rail designs. |
| Integrated PMOS gate driver | TG pin drives external PMOS to disconnect LED string during PWM off-time-minimizes output capacitor discharge and improves dimming fidelity. |
| Wide input voltage range | 3V–30V operation with 40V transient tolerance-enables direct connection to unregulated 24V truck/bus systems without pre-regulation. |
Applications
| Automotive Headlamp Control | Industrial Display Backlighting |
|---|---|
Use Scenario: Adaptive front-lighting system (AFS) requiring dynamic beam shaping and intensity modulation across varying ambient conditions. IC Role / Device Role / Timing Role: Constant-current LED driver regulating 1.5A through high-power white LED arrays in buck configuration, with PWM dimming synchronized to vehicle CAN bus timing signals. Use Value: 3000:1 dimming range and open-LED fault detection ensure compliance with UNECE R112 safety standards and enable real-time beam calibration. | Use Scenario: High-brightness LCD backlight for factory HMIs operating in wide temperature (-40°C to 125°C) and EMI-heavy environments. IC Role / Device Role / Timing Role: Boost-mode LED driver powering 8-series white LEDs from 12V rail, using FB feedback for stable output and CTRL pin for ambient light compensation. Use Value: 2.3A switch and 45V rating support long LED strings; TSSOP package enables compact layout near display edge with minimal thermal derating. |
| Aerospace Avionic Lighting | Barcode Scanner Illumination |
Use Scenario: Cockpit instrument panel backlighting requiring MIL-STD-704 compliant operation and zero-flicker performance under vibration. IC Role / Device Role / Timing Role: Buck-boost LED driver maintaining constant 300mA current across 8V–16V input variation, using SYNC to lock switching to master avionics clock. Use Value: 250kHz–2.5MHz frequency agility avoids interference with RF comms bands; exposed-pad TSSOP aids conduction cooling in sealed enclosures. | Use Scenario: High-speed handheld barcode scanner needing rapid LED strobe pulses with consistent luminance across battery voltage decay. IC Role / Device Role / Timing Role: Buck-mode driver delivering 1A peak current to red LED array, controlled by microcontroller PWM signal with stored VC state for sub-µs recovery. Use Value: 100mV current sense and <1µA shutdown current extend battery life; 16-pin TSSOP simplifies automated assembly on dense scanner PCBs. |
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; no integrated current sense amplifier; requires external sense amp or shunt. | Better suited for >2A LED strings; lacks 100mV sense threshold and True Color PWM™ dimming. | Select when higher output current is required and external sensing is acceptable. |
| MAX16820ATP+ | 2.5A switch; fixed 500kHz frequency; no SYNC or adjustable RT; only 1000:1 PWM dimming. | Lower BOM count for cost-sensitive industrial lighting; no buck-boost capability. | Select for fixed-frequency, lower-complexity designs where 3000:1 dimming is not required. |
Compared with LTC3783EFE#PBF and MAX16820ATP+, the LT3518IFE#PBF uniquely combines 2.3A switching, 100mV precision current sensing, 3000:1 PWM dimming, and triple topology support in a single TSSOP package-making it optimal for space-constrained, high-fidelity LED systems demanding reliability across automotive and avionic temperature ranges.
Availability
LT3518IFE#PBF is available at Aetrix Electronics and suitable for automotive headlamps, industrial display backlighting, and avionic lighting requiring stable component supply, extended temperature operation (-40°C to 125°C), and long-term production continuity.
Supply support for LT3518IFE#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) is a global leader in high-performance analog, mixed-signal, and power management semiconductors, serving precision instrumentation, industrial, automotive, and aerospace markets.
The LT3518 belongs to Linear's high-reliability LED driver product line, designed specifically for demanding constant-current applications requiring robust fault protection, wide input range, and ultra-precise dimming in harsh environments.
FAQ
What is the maximum continuous input voltage rating for LT3518IFE#PBF?
The LT3518IFE#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 spikes. This rating is confirmed in the Absolute Maximum Ratings table and applies specifically to the FE-grade TSSOP package used in LT3518IFE#PBF.
Does LT3518IFE#PBF support buck-boost topology, and how is it configured?
Yes, LT3518IFE#PBF supports buck-boost operation as explicitly stated in the Features and Applications sections. Configuration requires external components arranged per Figure 4 in the datasheet: FB connects to a resistor divider referenced to the LED string cathode, and the TG pin drives a PMOS switch to level-shift the feedback reference. This enables regulation across input voltages both above and below the LED forward voltage.
What is the function of the TG pin on LT3518IFE#PBF, and what voltage does it drive?
The TG pin on LT3518IFE#PBF is a top-gate driver output that controls an external PMOS transistor to disconnect the LED string during PWM off-time. It delivers an inverted PWM signal with a 7V clamp relative to ISP, ensuring gate-source voltage stays within safe limits (e.g., VISP = 24V → TG max = 17V). This feature minimizes output capacitor discharge and improves dimming fidelity in LT3518IFE#PBF designs.
Can LT3518IFE#PBF operate without an external RT resistor?
No-LT3518IFE#PBF requires an external resistor connected from the RT pin to GND for proper oscillator operation. Leaving RT open or loading it with capacitance will cause malfunction. The resistor value sets switching frequency from 250kHz to 2.5MHz (e.g., 16.9kΩ = 1MHz); if synchronization is needed, RT must be set to generate a frequency 20% slower than the external SYNC signal.
How does LT3518IFE#PBF implement open LED protection?
LT3518IFE#PBF detects open-circuit conditions by monitoring the ISP–ISN differential voltage. When no LED current flows, the sense voltage collapses below the operational threshold, triggering automatic shutdown of the main switch and disabling output. This protects both the LED string and internal switch from overvoltage stress-confirmed in the Features list and Typical Application circuits (e.g., TA05a with open-LED fault response).
LT3518IFE#PBF Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- -
- Package/Case:
- 16-TSSOP (0.173", 4.40mm Width) 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-TSSOP-EP
LT3518IFE#PBF FAQ
1.How can I place an order for LT3518IFE#PBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LT3518IFE#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 LT3518IFE#PBF reliable?
The price and inventory of LT3518IFE#PBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LT3518IFE#PBF is usually 5 days.
3.What payment methods are accepted for LT3518IFE#PBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LT3518IFE#PBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LT3518IFE#PBF?
LT3518IFE#PBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LT3518IFE#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 LT3518IFE#PBF?
For technical support, including LT3518IFE#PBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LT3518IFE#PBF requirements.
6.How does Aetrix verify that LT3518IFE#PBF is sourced from the original manufacturer or authorized distributors?
All LT3518IFE#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 LT3518IFE#PBF meets industry standards.
7.What is the process for return or replacement of LT3518IFE#PBF?
All LT3518IFE#PBF units undergo pre-shipment inspection (PSI). If there is an issue with LT3518IFE#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 LT3518IFE#PBF part is unused and in its original packaging.
Return procedure for LT3518IFE#PBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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