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Analog Devices Inc. LT3517IUF#TRPBF
- Part No.:
- LT3517IUF#TRPBF
- Manufacturer:
- Analog Devices Inc.
- Category:
- LED Drivers
- Package:
- 16-WQFN Exposed Pad
- Datasheet:
-
LT3517IUF#TRPBF.pdf
- Description:
- IC LED DRVR RGLTR PWM 1.5A 16QFN
- Quantity:
- Payment:
- Shipping:
Inventory:2,500
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Product details
Overview
LT3517IUF#TRPBF from Analog Devices (formerly Linear Technology) is a constant-frequency current-mode DC/DC LED driver IC with an integrated 1.5A, 45V internal power switch, supporting boost, buck, and buck-boost topologies. It delivers precise constant-current regulation via 100mV high-side current sensing, enables 5000:1 true-color PWM dimming, and operates from 3V to 30V input with transient tolerance up to 40V - used in automotive display backlighting and avionic lighting systems.
For engineers reviewing the LT3517IUF#TRPBF datasheet, LT3517IUF#TRPBF pinout, LT3517IUF#TRPBF application, or LT3517IUF#TRPBF equivalent, key selection criteria include its dual-loop (voltage + current) regulation architecture, programmable 250kHz–2.5MHz switching frequency, open-LED protection, PMOS gate driver for LED disconnect, and thermal performance in the 4mm × 4mm QFN package with exposed pad.
Technical Context
The LT3517IUF#TRPBF implements a dual-loop control system: the current loop regulates LED current using a 100mV sense threshold referenced to CTRL voltage (0–1V), while the voltage loop monitors FB pin against 1.01V reference for overvoltage protection. The internal 1.5A/45V N-channel MOSFET switch operates in fixed-frequency current-mode mode with slope compensation.
It supports external synchronization via SYNC pin (with RT resistor set 20% below sync frequency), soft-start via SS pin, and analog dimming via CTRL pin (10:1 range). Gate drive for external PMOS disconnect is provided on TG pin with 7V clamp, and TGEN enables/disables that function.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Switch Current Limit | 1.5A typical; sets maximum peak inductor current for reliable operation at full load |
| Input Voltage Range | 3V to 30V continuous, 40V transient; supports wide automotive battery range including cold-crank and load-dump conditions |
| Current Sense Threshold | 100mV ±3mV; enables accurate LED current setting with low-power, high-precision shunt resistor |
| Switching Frequency Range | 250kHz to 2.5MHz; adjustable via RT resistor or external SYNC signal for EMI optimization or compact layout |
| PWM Dimming Ratio | 5000:1 true-color; achieved by fast-switching PWM pin control with stored VC node state for minimal recovery delay |
| Operating Junction Temp | –40°C to 125°C; qualified for industrial and automotive under-hood applications with derating above 125°C |
| Shutdown Current | <1µA; ensures ultra-low quiescent power in standby or ignition-off states |
Pinout & Package
The LT3517IUF#TRPBF is housed in a 16-lead (4mm × 4mm) plastic QFN package with exposed thermal pad (Pin 17) soldered to PCB ground plane for thermal management and low-inductance GND return.
| 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 device; logic-low ≤0.45V disables with <1µA shutdown current |
| CTRL | Analog Current Setpoint | 0–1V input scales LED current threshold from 0 to 100mV; tied to VREF for full-scale operation |
| PWM | Digital Dimming Input | Active-low signal enabling 5000:1 PWM dimming; disables main switch and forces TG high during low phase |
| SYNC | External Clock Input | Accepts 0.4V–1.5V logic-low/high; synchronizes switching edge with external clock source |
| FB | Voltage Feedback Input | Regulates output voltage to 1.01V; triggers overvoltage shutdown if exceeded |
| RT | Frequency Programming | Resistor-to-GND sets oscillator frequency; open circuit prohibited; 4.02kΩ = 2.5MHz, 90.9kΩ = 250kHz |
| TG | PMOS Gate Driver Output | Drives external PMOS between VISP and (VISP – 7V); includes internal 7V clamp for gate protection |
| TGEN | PMOS Enable Control | ≥1.5V enables TG output; grounded to disable PMOS disconnect function |
| ISP / ISN | High-Side Current Sense | Differential inputs for 100mV sense resistor; rail-to-rail operation supports wide LED string voltage range |
| VREF | 2.0V Reference Output | Stable 2.0V ±20mV reference; supplies up to 100µA for CTRL bias or external circuitry |
| VC | Error Amplifier Output | gm amplifier output (550µS); stabilized with external RC network for loop compensation |
| SS | Soft-Start Control | Capacitor-to-GND controls ramp rate of internal reference; 0.1µF yields typical start-up profile |
| GND | Ground Reference | Exposed pad (Pin 17) must be soldered to PCB ground plane for thermal and electrical integrity |
Key Features
| Feature | Design Value |
|---|---|
| Triple-Mode Topology Support | Configurable as boost, buck, or buck-boost via external component selection - eliminates need for multiple driver ICs across lighting designs |
| True-Color PWM Dimming | 5000:1 ratio with preserved color fidelity due to zero-recovery-time VC node hold and fast PMOS disconnect |
| Integrated PMOS Gate Driver | TG pin drives external PMOS to isolate LED string during PWM off-time, preventing output capacitor discharge and improving dimming linearity |
| Open-LED Protection | Automatic shutdown when ISP–ISN voltage exceeds threshold - prevents overvoltage damage to LEDs and driver during fault conditions |
| Transient-Robust Input Stage | Rated for 40V nonrepetitive transients - meets ISO 7637-2 pulse 5a requirements for automotive 12V systems |
Applications
| Automotive Display Backlighting | Avionic Cabin Lighting |
|---|---|
Use Scenario: Driving white LED strings in TFT-LCD instrument clusters and center displays under varying battery voltage (9V–16V) and temperature (–40°C to 105°C). IC Role / Device Role / Timing Role: Constant-current LED driver operating in buck mode with 1.5A switch, synchronized to system clock via SYNC pin to suppress EMI in sensitive RF zones. Use Value: Enables flicker-free, high-contrast backlighting with 5000:1 dimming for daylight-to-night adaptation without color shift. | Use Scenario: Powering certified LED luminaires in aircraft cabin emergency path lighting and reading lights, requiring DO-160D Section 22 compliance. IC Role / Device Role / Timing Role: Buck-boost LED driver delivering regulated 300mA to 12V LED loads across 8V–16V input range, with open-LED fault detection and thermal derating. Use Value: Ensures fail-safe operation with automatic shutdown on LED open-circuit, meeting FAA lighting reliability mandates. |
| Industrial Scanner Illumination | Medical Imaging Panel Lighting |
Use Scenario: High-speed linear LED array illumination in barcode and document scanners requiring precise current stability during rapid PWM modulation. IC Role / Device Role / Timing Role: Boost-mode LED driver with 2.5MHz switching and 100ns gate delays, controlled via external PWM signal for sub-millisecond exposure timing. Use Value: Delivers consistent photon flux across scan lines with <±1% current ripple, eliminating image banding artifacts. | Use Scenario: Low-noise, EMI-controlled LED backlighting for diagnostic-grade medical LCD panels where electromagnetic interference could disrupt sensor signals. IC Role / Device Role / Timing Role: Constant-voltage + constant-current hybrid regulator in buck configuration, using FB loop for overvoltage clamp and current loop for brightness stability. Use Value: Maintains IEC 60601-1 EMC compliance with minimized SW node area and synchronized switching to avoid critical frequency bands. |
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 3A switch current, 60V rating, but no integrated current sense amp; requires external sense resistor and op-amp for current loop | Targeted at higher-power LED arrays (>2A) and industrial UV curing; lacks 5000:1 PWM dimming and open-LED protection | Select when >2A output or >45V input is required; accept added BOM complexity for extended voltage/current range |
| MAX16820ATP+ | Lower 1.2A switch, fixed 1MHz frequency, no SYNC or TGEN pins; uses 200mV current sense threshold | Optimized for cost-sensitive consumer backlighting; no buck-boost support or PMOS disconnect driver | Select for simple boost-only designs with moderate dimming (1000:1) and no thermal or fault-protection requirements |
Compared with LTC3783EFE#TRPBF and MAX16820ATP+, the LT3517IUF#TRPBF uniquely integrates dual-loop regulation, 5000:1 PWM dimming, and PMOS gate drive in a single 4mm × 4mm QFN - reducing solution size and simplifying design for mid-power automotive and avionic lighting where reliability and dimming fidelity are critical.
Availability
LT3517IUF#TRPBF is available at Aetrix Electronics and suitable for automotive display backlighting, avionic cabin lighting, and industrial scanner illumination requiring stable component supply, long-term lifecycle support, and AEC-Q200-aligned thermal robustness.
Supply support for LT3517IUF#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, Inc. (ADI) is a global leader in high-performance analog, mixed-signal, and digital signal processing semiconductors, formed through the acquisition of Linear Technology in 2017.
The LT3517IUF#TRPBF belongs to ADI's legacy Linear Technology LED driver product line, engineered specifically for high-reliability constant-current LED applications demanding wide input range, multi-topology flexibility, and precision dimming in harsh environments.
FAQ
What is the maximum continuous input voltage rating for the LT3517IUF#TRPBF?
The LT3517IUF#TRPBF has a maximum continuous input voltage rating of 30V at VIN, SHDN, PWM, and TGEN pins. It tolerates nonrepetitive 40V transients for up to one second per Absolute Maximum Ratings - making it suitable for automotive 12V systems subject to load dump events. Operation beyond 30V continuously risks exceeding junction temperature limits and violating SOA constraints.
How does the LT3517IUF#TRPBF achieve 5000:1 PWM dimming without color shift?
The LT3517IUF#TRPBF achieves 5000:1 true-color PWM dimming by combining fast PWM pin response (<200ns propagation delay), stored VC node charge retention during PWM low periods, and synchronous PMOS LED disconnect via TG/TGEN. This preserves LED forward voltage stability and eliminates output capacitor discharge - maintaining consistent current waveform shape and spectral output across the full dimming range.
Can the LT3517IUF#TRPBF operate in buck-boost mode with open-LED protection enabled?
Yes, the LT3517IUF#TRPBF supports buck-boost topology with open-LED protection active. Its current-sense amplifier monitors ISP–ISN differential voltage; if the LED string opens, ISP–ISN drops below 10mV (10% scale), triggering automatic shutdown within one switching cycle. This behavior is topology-agnostic and functions identically in boost, buck, and buck-boost configurations per the LT3517 datasheet Figure 1 and Applications Information section.
What is the purpose of the TGEN pin on the LT3517IUF#TRPBF, and how should it be configured?
The TGEN pin on the LT3517IUF#TRPBF enables or disables the internal PMOS gate driver output on TG. When TGEN is pulled ≥1.5V (e.g., to VREF), TG actively drives external PMOS to disconnect the LED string during PWM low time. When TGEN is grounded, TG is disabled and floats. Leaving TGEN unconnected is not recommended due to its internal 40kΩ pull-down; tie to VREF or GND based on whether PMOS disconnect is required in the application.
Does the LT3517IUF#TRPBF require external compensation components, and where are they connected?
Yes, the LT3517IUF#TRPBF requires external compensation on the VC pin to stabilize the current/voltage control loop. A typical configuration uses a 10nF capacitor from VC to GND; a series resistor may be added to increase slew rate for improved transient response to VIN or CTRL changes. Compensation values depend on selected inductor, output capacitor, and operating point - refer to the Loop Compensation section of the LT3517 datasheet for design equations and stability criteria.
LT3517IUF#TRPBF Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- True Color PWM™
- 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:
- 1.5A (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)
LT3517IUF#TRPBF FAQ
1.How can I place an order for LT3517IUF#TRPBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LT3517IUF#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 LT3517IUF#TRPBF reliable?
The price and inventory of LT3517IUF#TRPBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LT3517IUF#TRPBF is usually 5 days.
3.What payment methods are accepted for LT3517IUF#TRPBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LT3517IUF#TRPBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LT3517IUF#TRPBF?
LT3517IUF#TRPBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LT3517IUF#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 LT3517IUF#TRPBF?
For technical support, including LT3517IUF#TRPBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LT3517IUF#TRPBF requirements.
6.How does Aetrix verify that LT3517IUF#TRPBF is sourced from the original manufacturer or authorized distributors?
All LT3517IUF#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 LT3517IUF#TRPBF meets industry standards.
7.What is the process for return or replacement of LT3517IUF#TRPBF?
All LT3517IUF#TRPBF units undergo pre-shipment inspection (PSI). If there is an issue with LT3517IUF#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 LT3517IUF#TRPBF part is unused and in its original packaging.
Return procedure for LT3517IUF#TRPBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
LT3517IUF#TRPBF Tags
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