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Analog Devices Inc. LT3518IFE#TRPBF
- Part No.:
- LT3518IFE#TRPBF
- Manufacturer:
- Analog Devices Inc.
- Category:
- LED Drivers
- Package:
- 16-TSSOP (0.173", 4.40mm Width) Exposed Pad
- Datasheet:
-
LT3518IFE#TRPBF.pdf
- Description:
- IC LED DRV RGLTR PWM 16TSSOP
- Quantity:
- Payment:
- Shipping:
Inventory:3,550
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Product details
Overview
LT3518IFE#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 - used in automotive lighting and display backlighting systems.
For engineers reviewing the LT3518IFE#TRPBF datasheet, LT3518IFE#TRPBF pinout, LT3518IFE#TRPBF application, or LT3518IFE#TRPBF equivalent, this page provides verified topology flexibility (buck/boost/buck-boost), confirmed 100mV current sense threshold, validated 2.3A switch current limit, and real-world thermal derating guidance for industrial-grade operation up to 125°C junction temperature.
Technical Context
The LT3518IFE#TRPBF integrates dual-loop control: a voltage loop (FB pin, 1.01V threshold) and a current loop (ISP/ISN differential input) that jointly determine operating mode-constant-current dominates when LED load demands it; constant-voltage activates during overvoltage conditions. Its internal transconductance error amplifier (550 µS) drives the VC pin for loop compensation, while the 250kHz–2.5MHz adjustable oscillator (via RT resistor or SYNC input) supports layout-optimized frequency selection.
It features rail-to-rail current sense operation, open-LED protection via FB overvoltage shutdown, and a dedicated PMOS gate driver (TG pin) with 7V clamp referenced to ISP, enabling safe LED string disconnect during PWM off-time. The CTRL pin linearly scales the current sense threshold from 0 to 100mV (0–1V input), enabling analog dimming with 10:1 ratio alongside PWM.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Switch Current Limit | 2.3A typical - sets maximum peak inductor current; defines usable LED string power in buck mode at 30V input. |
| Current Sense Threshold | 100mV ±3% - determines full-scale LED current via external RSENSE; enables accurate, low-loss current programming. |
| Input Voltage Range | 3V to 30V continuous - supports 12V/24V automotive rails and wide-input industrial supplies; tolerates 40V transients. |
| Switching Frequency Range | 250kHz to 2.5MHz - selectable via RT resistor or external SYNC clock; higher frequencies reduce inductor/capacitor size. |
| Dimming Capability | 3000:1 PWM + 10:1 analog (CTRL) - enables flicker-free, color-stable dimming in display backlights and avionic lighting. |
| Junction Temperature Range | –40°C to 125°C - qualified for extended-temperature industrial and automotive under-hood applications. |
| Shutdown Current | <1µA - minimizes battery drain in always-on vehicle systems during sleep mode. |
Pinout & Package
The LT3518IFE#TRPBF is packaged in a 16-pin plastic TSSOP (FE package) with exposed pad soldered to GND for thermal and electrical integrity. Pin 1 is located at bottom-left corner when notch faces upward.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| VIN | Main input supply rail | Accepts 3V–30V; requires local 2.2µF ceramic bypass capacitor to suppress switching noise. |
| SHDN | Enable/disable control | Logic-high ≥1.2V enables operation; ≤0.45V disables with <1µA quiescent draw. |
| PWM | Digital dimming input | Active-low signal; disables main switch and forces TG high to disconnect LED string. |
| CTRL | Analog current setpoint | 0–1V input scales current sense threshold from 0 to 100mV; ties to VREF for full scale. |
| SYNC | External clock input | Accepts 1.5–5V logic; synchronizes switching edge to external source for EMI reduction. |
| FB | Voltage feedback input | Regulates output to 1.01V threshold; triggers open-LED protection if voltage exceeds limit. |
| SS | Soft-start timing node | Connects to 0.1µF capacitor to ramp VC voltage and limit inrush current at startup. |
| RT | Oscillator frequency set | Resistor to GND programs frequency; 16.9kΩ yields 1MHz; must not be left floating. |
| SW | Power switch drain | High dv/dt node; requires minimal trace area and ground plane underneath to reduce EMI. |
| TG | PMOS gate driver output | Drives external PMOS between ISP and load; clamped to ISP – 7V for gate protection. |
| ISP / ISN | High-side current sense inputs | Differential pair measuring voltage across RSENSE; rail-to-rail operation supports full input range. |
| VREF | 2.0V precision reference | Stable 2.0V ±2% output; sources/sinks up to 100µA; used to bias CTRL and RT networks. |
| VC | Error amplifier output | gm = 550µS; connects to RC compensation network for loop stability in constant-current mode. |
| TGEN | Top-gate enable control | Logic-high ≥1.5V enables TG driver; internal 40kΩ pull-down ensures disable when unconnected. |
| GND | Ground reference | Exposed pad (Pin 16) must be soldered to PCB ground plane for thermal dissipation and noise immunity. |
Key Features
| Feature | Design Value |
|---|---|
| True Color PWM™ Dimming | 3000:1 ratio preserves LED chromaticity across dimming range - critical for medical displays and cockpit lighting. |
| Integrated 2.3A, 45V Switch | Eliminates external MOSFET in mid-power LED drivers (≤15W), reducing BOM count and layout complexity. |
| 100mV High-Side Current Sense | Minimizes power loss and heat generation in RSENSE; enables accurate current regulation independent of LED forward voltage. |
| Buck/Boost/Buck-Boost Flexibility | Single IC supports multiple topologies - simplifies platform design across varying input/output voltage requirements. |
| Open LED Protection | Automatic shutdown via FB pin monitoring prevents overvoltage damage to LEDs and driver during string failure. |
| Adjustable 250kHz–2.5MHz Frequency | Enables optimization for efficiency (lower fSW) or compactness (higher fSW); avoids AM radio band interference. |
Applications
| Automotive Headlamp Control | Industrial Display Backlighting |
|---|---|
Use Scenario: Adaptive front-lighting system (AFS) requiring dynamic beam shaping and stepless dimming across temperature extremes. IC Role / Device Role / Timing Role: Constant-current LED driver regulating 1–3A strings in buck configuration; uses PWM+CTRL hybrid dimming for smooth transitions. Use Value: Maintains consistent lumen output and color point from –40°C to 125°C ambient; 3000:1 dimming enables compliance with UNECE R149 glare limits. | Use Scenario: High-brightness LCD backlight for factory HMIs operating in 24V DC environments with EMI constraints. IC Role / Device Role / Timing Role: Boost-mode driver powering 12–24 white LEDs in series; synchronized to system clock via SYNC pin to suppress conducted emissions. Use Value: 2.5MHz switching enables <3mm² solution size; open-LED protection prevents catastrophic failure during field maintenance. |
| Avionic Cabin Lighting | Barcode Scanner Illumination |
Use Scenario: FAA-certified LED cabin lights needing DO-160G Section 22 lightning surge immunity and low EMI. IC Role / Device Role / Timing Role: Buck-boost driver accommodating 18–32V aircraft bus variation while maintaining constant LED current. Use Value: 40V transient rating withstands load-dump events; exposed-pad TSSOP meets thermal derating requirements for sealed enclosures. | Use Scenario: High-speed handheld barcode scanner requiring strobed illumination synchronized to image capture. IC Role / Device Role / Timing Role: PWM-controlled buck driver delivering 1.5A pulses at 120Hz with <3µs minimum on-time. Use Value: 3000:1 dimming ratio enables precise exposure control; fast recovery (<10µs) after PWM off preserves scan 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#TRPBF | Higher 4A switch current; supports SEPIC/Cuk; no integrated current sense amp - requires external op-amp for CC mode. | Targeted at >20W LED arrays; lacks 100mV sense threshold and True Color PWM™; needs more external components. | Choose LTC3783EFE#TRPBF only when >2.3A peak current or multi-topology flexibility beyond buck/boost/buck-boost is required. |
| MAX16820ATP+T | Fixed 2MHz fSW; 1.5A switch; 200mV current sense; no SYNC or analog dimming - PWM-only dimming at 1000:1 max. | Optimized for cost-sensitive consumer lighting; lacks open-LED protection and thermal grade support above 85°C. | Choose MAX16820ATP+T only for low-complexity, fixed-frequency 1.5A applications where extended temperature range and hybrid dimming are unnecessary. |
Compared with LTC3783EFE#TRPBF and MAX16820ATP+T, the LT3518IFE#TRPBF uniquely combines 2.3A/45V integration, 100mV current sensing, 3000:1 PWM dimming, and –40°C to 125°C qualification - making it optimal for space-constrained, thermally demanding LED systems requiring both precision current regulation and robust fault protection.
Availability
LT3518IFE#TRPBF is available at Aetrix Electronics and suitable for automotive headlamps, industrial HMI backlights, avionic cabin lighting, and barcode scanner illumination requiring stable component supply across extended temperature ranges and long production lifecycles.
Supply support for LT3518IFE#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 (now part of Analog Devices, Inc., following merger with Linear Technology) designs high-performance analog, mixed-signal, and power management ICs for precision, reliability, and rugged operation.
The LT3518IFE#TRPBF belongs to Linear's LED driver product line, engineered specifically for high-efficiency, multi-topology constant-current LED regulation in harsh environments - emphasizing thermal robustness, dimming fidelity, and system-level fault protection.
FAQ
What is the maximum continuous input voltage rating for the LT3518IFE#TRPBF?
The LT3518IFE#TRPBF supports continuous operation up to 30V on the VIN pin. It tolerates nonrepetitive 40V transients for up to one second, per Absolute Maximum Ratings. Exceeding 30V continuously risks thermal overload, especially at high duty cycles or elevated ambient temperatures - proper heatsinking via the exposed pad is essential above 24V input.
How does the LT3518IFE#TRPBF achieve 3000:1 PWM dimming ratio?
The LT3518IFE#TRPBF achieves 3000:1 PWM dimming by combining precise switch timing control, stored VC node state during PWM low periods, and external PMOS LED disconnect via the TG pin. Minimum PWM pulse width is constrained by switching frequency - e.g., at 2MHz, 3µs minimum width yields 9ms/3µs = 3000:1 ratio. The LT3518IFE#TRPBF maintains current accuracy across this range without color shift.
Can the LT3518IFE#TRPBF operate in buck, boost, and buck-boost modes with the same PCB layout?
No - while the LT3518IFE#TRPBF supports all three topologies internally, each requires distinct external component placement: buck needs input capacitor near VIN and Schottky diode on SW; boost requires output capacitor on PVIN and diode anode to SW; buck-boost demands careful grounding of ISP/ISN and isolation of feedback divider. Shared layout is not feasible without performance compromise or reliability risk.
What is the function of the TGEN pin on the LT3518IFE#TRPBF?
The TGEN pin enables or disables the internal PMOS gate driver (TG pin). When pulled ≥1.5V, it activates the TG output to drive an external PMOS transistor for LED string disconnect during PWM off-time - preventing output capacitor discharge and improving dimming response. When grounded or left floating (internal 40kΩ pull-down), TG remains inactive. This feature is critical for maintaining fast PWM recovery in the LT3518IFE#TRPBF.
Does the LT3518IFE#TRPBF provide open-LED protection, and how does it work?
Yes, the LT3518IFE#TRPBF provides open-LED protection via its FB pin. When the LED string opens, output voltage rises until FB exceeds 1.01V, triggering automatic shutdown of the main switch. This prevents overvoltage stress on downstream components and the LT3518IFE#TRPBF itself. Recovery is automatic once the fault clears and FB drops below threshold - no latch or manual reset is required.
LT3518IFE#TRPBF Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- -
- Package/Case:
- 16-TSSOP (0.173", 4.40mm Width) 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-TSSOP-EP
LT3518IFE#TRPBF FAQ
1.How can I place an order for LT3518IFE#TRPBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LT3518IFE#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 LT3518IFE#TRPBF reliable?
The price and inventory of LT3518IFE#TRPBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LT3518IFE#TRPBF is usually 5 days.
3.What payment methods are accepted for LT3518IFE#TRPBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LT3518IFE#TRPBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LT3518IFE#TRPBF?
LT3518IFE#TRPBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LT3518IFE#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 LT3518IFE#TRPBF?
For technical support, including LT3518IFE#TRPBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LT3518IFE#TRPBF requirements.
6.How does Aetrix verify that LT3518IFE#TRPBF is sourced from the original manufacturer or authorized distributors?
All LT3518IFE#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 LT3518IFE#TRPBF meets industry standards.
7.What is the process for return or replacement of LT3518IFE#TRPBF?
All LT3518IFE#TRPBF units undergo pre-shipment inspection (PSI). If there is an issue with LT3518IFE#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 LT3518IFE#TRPBF part is unused and in its original packaging.
Return procedure for LT3518IFE#TRPBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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