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Analog Devices Inc. LT3517IUF#PBF
- Part No.:
- LT3517IUF#PBF
- Manufacturer:
- Analog Devices Inc.
- Category:
- LED Drivers
- Package:
- 16-WQFN Exposed Pad
- Datasheet:
-
LT3517IUF#PBF.pdf
- Description:
- IC LED DRVR RGLTR PWM 1.5A 16QFN
- Quantity:
- Payment:
- Shipping:
Inventory:555
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Product details
Overview
LT3517IUF#PBF from Analog Devices is a constant-frequency current-mode DC/DC LED driver IC with an internal 1.5A, 45V 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 across 3V–30V input with transient tolerance to 40V - ideal for automotive display backlighting requiring robust thermal performance and wide dimming range.
For engineers reviewing the LT3517IUF#PBF datasheet, LT3517IUF#PBF pinout, LT3517IUF#PBF application, or LT3517IUF#PBF equivalent, key selection criteria include its 16-lead 4mm × 4mm QFN package, –40°C to 125°C operating junction temperature, adjustable switching frequency (250kHz–2.5MHz), open-LED protection, and dual dimming control (PWM + CTRL analog).
Technical Context
The LT3517IUF#PBF integrates a current-sense amplifier with rail-to-rail operation and a transconductance error amplifier (550 µS) driving the VC node for loop compensation. Its dual-loop architecture simultaneously monitors FB (1.01V threshold) for overvoltage protection and ISP/ISN differential voltage for LED current regulation, enabling seamless transition between constant-current and constant-voltage modes.
It features synchronous frequency adjustment via RT resistor or external clock on SYNC pin (with 20% slower RT setting), programmable soft-start via SS capacitor, and integrated PMOS gate driver (TG) with 7V clamp and TGEN enable control - all optimized for low EMI layout using the exposed pad as GND and minimized SW node area.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Switch Current Limit | 1.5A typical; sets maximum peak inductor current for reliable LED string drive without external current-limiting components. |
| Input Voltage Range | 3V to 30V continuous, 40V transient; supports 12V/24V automotive rails and accommodates load-dump events without shutdown. |
| Current Sense Threshold | 100mV ±3mV; enables accurate LED current regulation with minimal power loss in sense resistor (e.g., 100mΩ at 1A). |
| Switching Frequency Range | 250kHz to 2.5MHz; allows trade-off between efficiency (lower fSW) and component size (higher fSW) via RT resistor or SYNC input. |
| PWM Dimming Ratio | 5000:1 true-color; achieved by disabling switching during PWM low phase while preserving VC node charge for fast recovery. |
| Operating Temperature | –40°C to +125°C junction; qualified for industrial and automotive lighting environments with derated lifetime above 125°C. |
| Shutdown Current | <1µA; ensures negligible battery drain in always-on vehicle systems during sleep mode. |
Pinout & Package
The LT3517IUF#PBF 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; 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. |
| CTRL | Analog current setpoint | Sets VISP–ISN threshold from 0V to 1V (0–100mV), enabling 10:1 analog dimming when used with PWM. |
| PWM | Digital dimming input | Active-low signal; disables switching and preserves VC state for sub-µs recovery and 5000:1 dimming fidelity. |
| SYNC | External clock input | Accepts TTL/CMOS clock; forces synchronization when RT is configured for 20% lower frequency than SYNC signal. |
| FB | Voltage feedback input | Regulates output to 1.01V; triggers overvoltage shutdown if exceeded - critical for open-LED protection in boost configurations. |
| RT | Frequency programming | Resistor-to-GND sets oscillator frequency (250kHz–2.5MHz); must not be left floating or capacitive-loaded. |
| TG | PMOS gate driver output | Drives external high-side PMOS disconnect switch; clamped to VISP – 7V to protect gate oxide. |
| TGEN | TG enable input | Logic-high (>1.5V) activates TG driver; internal 40kΩ pull-down ensures safe default-off state. |
| ISP / ISN | High-side current sense inputs | Differential pair measuring voltage across external sense resistor; rail-to-rail operation supports full LED string voltage range. |
| VREF | 2.0V reference output | Stable 2.0V ±20mV source; supplies bias for CTRL, RT, and external circuitry with up to 100µA sink capability. |
| VC | Error amplifier output | gm amplifier output (550µS); external RC network compensates control loop for stability across operating conditions. |
| SS | Soft-start control | Capacitor-to-GND controls ramp rate of internal reference; prevents inrush current and output overshoot at startup. |
| GND | Ground reference | Exposed thermal pad (Pin 17); must be soldered to solid PCB ground plane with multiple thermal vias for thermal and EMI performance. |
Key Features
| Feature | Design Value |
|---|---|
| True Color PWM™ dimming | 5000:1 ratio with preserved color fidelity via zero-current PWM blanking and stored VC state for <1µs recovery. |
| Integrated 1.5A/45V switch | Eliminates external MOSFET in most LED driver designs; reduces BOM count and layout complexity for compact solutions. |
| Multi-topology support | Native operation in boost, buck, and buck-boost modes enables single-IC solution across diverse LED voltage/current requirements. |
| Open-LED protection | FB pin monitoring shuts down switch if output exceeds 1.01V - essential for fail-safe operation in automotive backlighting. |
| Thermal-enhanced QFN | 4mm × 4mm footprint with exposed GND pad achieves θJA = 36°C/W, enabling 1.5A operation at 125°C ambient without heatsink. |
Applications
| Automotive Display Backlighting | Avionic Cabin Lighting |
|---|---|
Use Scenario: Driving white LED strings in TFT-LCD instrument clusters and center displays under 12V/24V vehicle battery with load-dump transients. IC Role / Device Role / Timing Role: Constant-current LED driver with open-circuit detection and 5000:1 PWM dimming for glare-free night vision compliance. Use Value: Eliminates need for external current-sense op-amp and high-voltage PMOS disconnect switch; withstands 40V transients per ISO 7637-2. | Use Scenario: Powering red/green status indicators and reading lights in aircraft cabins where EMI and reliability are mission-critical. IC Role / Device Role / Timing Role: Buck-mode LED controller with synchronized switching (via SYNC) to avoid interference with avionics RF bands. Use Value: Achieves >85% efficiency at 300mA/12V output with 2.5MHz operation, minimizing filter component size and weight. |
| Industrial Scanner Illumination | Medical Endoscope Light Source |
Use Scenario: High-intensity linear LED array illumination in barcode scanners requiring rapid on/off cycling and stable brightness. IC Role / Device Role / Timing Role: Boost-mode driver with programmable soft-start and 100mV current sensing for repeatable pulse-current accuracy. Use Value: Enables 200ns PWM edge response and <1% current ripple via 2.2µF X7R output capacitor - critical for motion-blur-free imaging. | Use Scenario: Regulated white LED light engine in portable endoscopes powered by Li-ion batteries (3.0–4.2V nominal). IC Role / Device Role / Timing Role: Buck-boost topology maintains constant 700mA LED current across full battery discharge curve. Use Value: Supports 3V–30V input range and uses CTRL+PWM dual dimming to meet IEC 60601-1 photobiological safety limits. |
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 3A switch current, 60V rating, but no integrated current-sense amplifier; requires external sense resistor and op-amp. | Better suited for high-power (>2A) LED arrays; lacks native 100mV sense and True Color PWM dimming. | Select when higher output current or extended input voltage (up to 60V) is required, and board space allows added components. |
| MAX16820ATP+ | Fixed 2MHz switching, 1.2A switch, 40V rating; only supports boost topology and lacks buck/buck-boost flexibility. | Targeted at space-constrained boost-only applications; no TG driver or TGEN control for PMOS disconnect. | Choose for simple boost LED drivers where topology flexibility and multi-mode dimming are not needed. |
Compared with LTC3783EFE#PBF and MAX16820ATP+, the LT3517IUF#PBF provides integrated high-side current sensing, triple-topology operation, and industry-leading 5000:1 PWM dimming - making it optimal for automotive and avionic lighting where reliability, compactness, and dimming fidelity are prioritized over raw current headroom.
Availability
LT3517IUF#PBF is available at Aetrix Electronics and suitable for automotive display backlighting, avionic cabin lighting, and industrial scanner illumination requiring stable component supply across extended temperature ranges and long production lifecycles.
Supply support for LT3517IUF#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 industrial, automotive, communications, and healthcare markets.
The LT3517 belongs to Linear's high-reliability LED driver product line, designed specifically for demanding lighting applications requiring wide input range, multi-topology flexibility, and precision current regulation with integrated protection features.
FAQ
What is the maximum allowable input voltage for continuous operation of the LT3517IUF#PBF?
The LT3517IUF#PBF supports continuous input operation from 3V to 30V. It tolerates nonrepetitive 40V transients for up to one second, making it suitable for automotive 12V/24V systems subject to load-dump events per ISO 7637-2. Exceeding 30V continuously risks exceeding thermal limits and reducing device lifetime, especially above 125°C junction temperature.
How does the LT3517IUF#PBF achieve 5000:1 PWM dimming without color shift?
The LT3517IUF#PBF achieves 5000:1 True Color PWM™ dimming by fully disabling the main power switch and error amplifier during PWM low phase while preserving the charge state on the VC compensation node. This eliminates current ripple during off-time and ensures instantaneous, consistent current restoration at PWM rising edge - maintaining LED junction temperature stability and spectral output fidelity across the entire dimming range.
Can the LT3517IUF#PBF operate in buck mode with an input voltage higher than the LED string forward voltage?
Yes, the LT3517IUF#PBF natively supports buck-mode operation when VIN exceeds the LED string forward voltage. In this configuration, it regulates LED current via high-side sensing across ISP/ISN, uses the FB pin for overvoltage protection, and leverages the internal 1.5A switch for high efficiency. Typical applications include 24V-input automotive tail lamps driving 3–4 white LEDs in series (VF ≈ 12V).
What is the function of the TG and TGEN pins on the LT3517IUF#PBF?
The TG pin is a dedicated PMOS gate driver output that sources current to drive an external high-side PMOS transistor between VISP and the LED anode. The TGEN pin enables this driver: applying ≥1.5V activates TG, while grounding TGEN disables it. This allows active disconnection of the LED string during PWM off-time to prevent output capacitor discharge and improve dimming response - a key feature for flicker-free lighting.
Is the LT3517IUF#PBF RoHS-compliant and lead-free?
Yes, the LT3517IUF#PBF carries the #PBF suffix indicating lead-free finish and full RoHS compliance per EU Directive 2011/65/EU. The device uses matte tin plating over copper leads and meets JEDEC J-STD-020 moisture sensitivity level 3 (MSL3) for standard SMT assembly. Full compliance documentation is available through Analog Devices' quality portal.
LT3517IUF#PBF Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- True Color PWM™
- 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:
- 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#PBF FAQ
1.How can I place an order for LT3517IUF#PBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LT3517IUF#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 LT3517IUF#PBF reliable?
The price and inventory of LT3517IUF#PBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LT3517IUF#PBF is usually 5 days.
3.What payment methods are accepted for LT3517IUF#PBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LT3517IUF#PBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LT3517IUF#PBF?
LT3517IUF#PBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LT3517IUF#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 LT3517IUF#PBF?
For technical support, including LT3517IUF#PBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LT3517IUF#PBF requirements.
6.How does Aetrix verify that LT3517IUF#PBF is sourced from the original manufacturer or authorized distributors?
All LT3517IUF#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 LT3517IUF#PBF meets industry standards.
7.What is the process for return or replacement of LT3517IUF#PBF?
All LT3517IUF#PBF units undergo pre-shipment inspection (PSI). If there is an issue with LT3517IUF#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 LT3517IUF#PBF part is unused and in its original packaging.
Return procedure for LT3517IUF#PBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
LT3517IUF#PBF Tags
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