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Analog Devices Inc. LT3518HFE#TRPBF
- Part No.:
- LT3518HFE#TRPBF
- Manufacturer:
- Analog Devices Inc.
- Category:
- LED Drivers
- Package:
- 16-TSSOP (0.173", 4.40mm Width) Exposed Pad
- Datasheet:
-
LT3518HFE#TRPBF.pdf
- Description:
- IC LED DRV RGLTR PWM 16TSSOP
- Quantity:
- Payment:
- Shipping:
Inventory:2,010
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Product details
Overview
LT3518HFE#TRPBF from Analog Devices is a constant-frequency current-mode DC/DC LED driver IC with an internal 2.3A, 45V N-channel MOSFET switch, operating in boost, buck, and buck-boost topologies. It delivers constant-current regulation via 100mV high-side current sensing and supports true-color PWM dimming up to 3000:1 for display backlighting and automotive lighting systems.
For engineers reviewing the LT3518HFE#TRPBF datasheet, LT3518HFE#TRPBF pinout, LT3518HFE#TRPBF application, or LT3518HFE#TRPBF equivalent, key selection criteria include its –40°C to 150°C junction temperature rating, 16-pin TSSOP package, 250kHz–2.5MHz adjustable switching frequency, and dual dimming control (PWM + CTRL analog).
Technical Context
The LT3518HFE#TRPBF integrates a transconductance error amplifier (550 µS), dual feedback loops (voltage loop referenced to 1.01 V at FB, current loop controlled by VCTRL), and rail-to-rail current sense amplifier with 96–103 mV threshold accuracy. Its internal 2.3A/45V switch enables operation across 3V–30V input with transient tolerance to 40V.
It features synchronized switching (via SYNC pin), soft-start (SS pin), programmable oscillator (RT pin), and gate driver for external PMOS LED disconnect (TG pin). The CTRL pin sets LED current threshold linearly below 1V (ILED = VCTRL/(10·RSENSE)), clamping at 100 mV above 1V.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Switch Current Limit | 2.3 A typical - supports ≥1.5 A continuous LED current in buck mode with thermal margin at TJ ≤ 150°C |
| Input Voltage Range | 3 V to 30 V continuous - accommodates 12 V automotive and industrial supply rails with 40 V transient protection |
| Current Sense Threshold | 100 mV ±3% - enables precise, low-loss current regulation using standard 68 mΩ or 100 mΩ sense resistors |
| Switching Frequency Range | 250 kHz to 2.5 MHz - selectable via RT resistor or external SYNC clock for layout-optimized efficiency or size |
| PWM Dimming Ratio | 3000:1 - achieved with minimum 3 µs pulse width at 2 MHz fSW, enabling flicker-free high-resolution brightness control |
| Junction Temperature Range | –40°C to +150°C - qualified for under-hood automotive and high-ambient industrial LED lighting |
| Shutdown Current | <1 µA - ensures minimal battery drain in always-on vehicle systems during sleep mode |
Pinout & Package
The LT3518HFE#TRPBF is housed in a 16-lead plastic TSSOP package (FE) with exposed pad grounded for thermal management (θJA = 40°C/W, θJC(PAD) = 10°C/W). Pin 17 (exposed pad) must be soldered to PCB ground plane.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| VIN | Input supply rail | Accepts 3–30 V DC; requires local 2.2 µF ceramic bypass capacitor to suppress high di/dt noise |
| SHDN | Enable/disable control | Logic-high ≥1.2 V enables operation; logic-low ≤0.4 V disables switch and reduces quiescent current to <1 µA |
| FB | Voltage feedback input | Regulates output voltage to 1.01 V reference; used for overvoltage protection and CV mode in boost configurations |
| VC | Error amplifier output | gm = 550 µS; connects to RC compensation network to stabilize current/voltage control loops |
| CTRL | Analog current setpoint | Sets LED current threshold from 0–100 mV (0–1 V input); enables 10:1 analog dimming when combined with PWM |
| PWM | Digital dimming input | Active-low signal disables main switch and forces TG high; supports 3000:1 true-color PWM dimming |
| TG | Top-gate driver output | Drives external PMOS between ISP and (ISP – 7 V); includes internal 7 V clamp for safe gate drive |
| ISP/ISN | High-side current sense inputs | Differential pair measuring voltage across external RSENSE; rail-to-rail operation supports wide LED string voltage range |
| SYNC | External clock input | Accepts 0.4–1.5 V logic-low / 1.5–6 V logic-high; synchronizes switching edge to external timing source |
| RT | Oscillator frequency set | Resistor-to-GND sets fSW from 250 kHz–2.5 MHz; must not be left floating or capacitive-loaded |
Key Features
| Feature | Design Value |
|---|---|
| Integrated 2.3A/45V switch | Eliminates external MOSFET and gate driver in most medium-power LED drivers (≤15 W), reducing BOM count and layout area |
| 100 mV current sense threshold | Minimizes power loss in sense resistor (e.g., 68 mΩ dissipates only 15.5 mW at 1.5 A), improving thermal efficiency |
| Open LED protection | Disables switching and asserts fault condition if ISP–ISN voltage exceeds threshold, preventing overvoltage damage to LEDs |
| PMOS gate driver (TG pin) | Enables fast, low-loss LED string disconnect during PWM off-time, preserving output capacitor charge and minimizing recovery delay |
| Adjustable frequency (250 kHz–2.5 MHz) | Allows optimization: lower frequencies for high-efficiency >12 V input, higher frequencies for compact 5 V–12 V designs with small inductors/capacitors |
Applications
| Automotive Headlamp Control | Industrial Display Backlighting |
|---|---|
Use Scenario: Adaptive front-lighting system (AFS) requiring dynamic LED current adjustment across temperature and input voltage variation. IC Role / Device Role / Timing Role: Constant-current LED driver regulating 1–2 A through white LED strings in buck configuration, with open-LED fault detection and thermal derating at TJ > 125°C. Use Value: Maintains consistent lumen output over –40°C to +150°C ambient via integrated high-temp qualification and 100 mV sense accuracy, eliminating external calibration. | Use Scenario: High-brightness LCD panel backlight in factory HMIs where EMI-sensitive sensors operate nearby. IC Role / Device Role / Timing Role: Boost-mode LED driver powering 4–6 series white LEDs from 5 V rail, synchronized to system clock via SYNC pin to avoid beat frequencies. Use Value: 3000:1 PWM dimming at 100–120 Hz enables flicker-free grayscale rendering without audible coil whine, meeting IEC 62471 photobiological safety requirements. |
| Avionic Cabin Lighting | Barcode Scanner Illumination |
Use Scenario: Redundant LED lighting in pressurized aircraft cabins requiring fail-safe operation and low standby power. IC Role / Device Role / Timing Role: Buck-boost LED driver delivering 300 mA to mixed-color LED arrays from variable 8–16 V aircraft bus, with SHDN-controlled sleep mode. Use Value: <1 µA shutdown current extends battery backup runtime; 150°C rated junction ensures reliability during extended ground operations in hot tarmacs. | Use Scenario: Pulsed high-intensity illumination for CCD-based barcode readers requiring precise 10–100 µs light bursts. IC Role / Device Role / Timing Role: Constant-current driver in buck topology, triggered by microcontroller PWM signal with sub-microsecond TG-driven PMOS disconnect. Use Value: Fast TG turn-off (<200 ns) prevents LED current tailing, ensuring sharp optical pulse edges critical for decoding high-density QR codes. |
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 4 A switch current, 60 V rating, but no integrated current sense amplifier; requires external sense amp and feedback network | Better suited for >2 A LED strings or 48 V industrial bus inputs; lacks 100 mV sense and CTRL-based analog dimming | Select when scaling beyond 1.5 A or needing >30 V input; accept added complexity for higher power density |
| LM3409QMHX/NOPB | 3 A switch, 42 V rating, fixed 100 mV sense, but only buck topology support and no SYNC or TG pin | Optimized for cost-sensitive automotive buck-only designs; no buck-boost capability or external PMOS control | Choose for single-topology, high-volume automotive headlamp modules where topology flexibility is unnecessary |
Compared with LTC3783EFE#TRPBF and LM3409QMHX/NOPB, the LT3518HFE#TRPBF uniquely combines triple-topology operation, integrated 100 mV current sense, 3000:1 PWM dimming, and TG-driven PMOS disconnect in a single 16-pin TSSOP-enabling compact, thermally robust, and functionally complete LED driver designs without external amplifiers or gate drivers.
Availability
LT3518HFE#TRPBF is available at Aetrix Electronics and suitable for automotive lighting, industrial display backlighting, and avionic cabin illumination requiring stable component supply across extended temperature ranges and long production lifecycles.
Supply support for LT3518HFE#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) is a global leader in high-performance analog, mixed-signal, and power management semiconductors.
The LT3518HFE#TRPBF belongs to Linear Technology's LED driver product line, engineered specifically for high-reliability constant-current LED regulation in harsh environments including automotive, aerospace, and industrial applications.
FAQ
What is the maximum junction temperature rating for the LT3518HFE#TRPBF?
The LT3518HFE#TRPBF is guaranteed over the full –40°C to +150°C junction temperature range. This H-grade qualification enables reliable operation in under-hood automotive and high-ambient industrial environments where standard E- or I-grade variants (125°C max) would require derating or forced cooling. The LT3518HFE#TRPBF achieves this via enhanced process and packaging validation per Analog Devices' high-temp reliability standards.
How does the LT3518HFE#TRPBF implement open LED protection?
The LT3518HFE#TRPBF monitors the ISP–ISN differential voltage. If the sense voltage falls below 9 mV (10% scale) while PWM is active, the device interprets this as an open LED condition and disables the main switch, holding VC low and preventing uncontrolled voltage rise at the FB node. This feature is active in all topologies and requires no external circuitry-ensuring intrinsic protection for LED strings in automotive and avionic applications where failure modes must be contained.
Can the LT3518HFE#TRPBF operate in buck-boost mode, and what design considerations apply?
Yes, the LT3518HFE#TRPBF supports buck-boost operation, as confirmed in its functional description and Typical Application TA04. In buck-boost, the output voltage is level-shifted relative to ground, requiring careful FB resistor divider design per Equation 5 (VOUT = (R1/R2)·1.01 V + VBE(Q1)). Inductor selection follows DBOOST formula, and the TG pin must drive a PMOS between ISP and the LED cathode to maintain proper current path. Layout must minimize SW node area due to higher voltage stress versus pure buck.
What is the role of the TG pin on the LT3518HFE#TRPBF, and how is it used?
The TG (Top Gate) pin on the LT3518HFE#TRPBF is an inverted PWM output that drives the gate of an external PMOS transistor placed between ISP and the LED string anode. When PWM is low, TG goes high, turning off the PMOS and disconnecting the LED current path-preventing output capacitor discharge and enabling fast, clean dimming transitions. An internal 7 V clamp protects the PMOS gate, allowing safe operation even when ISP reaches 45 V. TGEN must be pulled high to enable TG functionality.
Does the LT3518HFE#TRPBF support synchronization to an external clock, and how is it configured?
Yes, the LT3518HFE#TRPBF supports external clock synchronization via the SYNC pin. To configure, connect a logic-level clock signal (0.4–1.5 V low, 1.5–6 V high) to SYNC and select the RT resistor to program a free-running frequency ~20% slower than the SYNC frequency. Synchronization occurs on the rising edge of SYNC with a fixed delay. This eliminates beat frequencies in multi-channel LED systems and reduces EMI by aligning switching edges across multiple LT3518HFE#TRPBF devices.
LT3518HFE#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 ~ 150°C (TJ)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 16-TSSOP-EP
LT3518HFE#TRPBF FAQ
1.How can I place an order for LT3518HFE#TRPBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LT3518HFE#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 LT3518HFE#TRPBF reliable?
The price and inventory of LT3518HFE#TRPBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LT3518HFE#TRPBF is usually 5 days.
3.What payment methods are accepted for LT3518HFE#TRPBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LT3518HFE#TRPBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LT3518HFE#TRPBF?
LT3518HFE#TRPBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LT3518HFE#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 LT3518HFE#TRPBF?
For technical support, including LT3518HFE#TRPBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LT3518HFE#TRPBF requirements.
6.How does Aetrix verify that LT3518HFE#TRPBF is sourced from the original manufacturer or authorized distributors?
All LT3518HFE#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 LT3518HFE#TRPBF meets industry standards.
7.What is the process for return or replacement of LT3518HFE#TRPBF?
All LT3518HFE#TRPBF units undergo pre-shipment inspection (PSI). If there is an issue with LT3518HFE#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 LT3518HFE#TRPBF part is unused and in its original packaging.
Return procedure for LT3518HFE#TRPBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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