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Analog Devices Inc. LT3517EFE#PBF
- Part No.:
- LT3517EFE#PBF
- Manufacturer:
- Analog Devices Inc.
- Category:
- LED Drivers
- Package:
- 16-TSSOP (0.173", 4.40mm Width) Exposed Pad
- Datasheet:
-
LT3517EFE#PBF.pdf
- Description:
- IC LED DRV RGLTR PWM 16TSSOP
- Quantity:
- Payment:
- Shipping:
Inventory:752
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Product details
Overview
LT3517EFE#PBF 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 and enables 5000:1 true-color PWM dimming with external PWM input. It is widely deployed in automotive interior lighting and industrial display backlighting requiring robust transient protection up to 40V.
For engineers reviewing the LT3517EFE#PBF datasheet, LT3517EFE#PBF pinout, LT3517EFE#PBF application, or LT3517EFE#PBF equivalent, key selection considerations include its 250kHz–2.5MHz programmable switching frequency, open-LED protection, gate driver for PMOS LED disconnect, and dual constant-current/constant-voltage regulation capability in the 16-pin TSSOP package.
Technical Context
The LT3517EFE#PBF implements a dual-loop control architecture: a voltage feedback loop (FB pin, 1.01V threshold) and a current feedback loop (ISP/ISN differential sense, 100mV full-scale), with the lower-demand loop dictating operating mode. Its internal 1.5A/45V N-channel MOSFET switch operates in fixed-frequency current-mode control, synchronized via SYNC pin or set by RT resistor.
It integrates a transconductance error amplifier (VC pin, 550µS gm), soft-start (SS pin), analog dimming via CTRL pin (0–1V input, 10:1 range), and a dedicated top-gate driver (TG pin) with 7V clamp for external PMOS LED disconnect-enabling fast PWM recovery and output capacitor hold-up during dimming off-cycles.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Switch Current Limit | 1.5A typical; ensures safe drive of high-brightness LED strings without external current limiting components. |
| Input Voltage Range | 3V to 30V continuous, 40V transient; supports 12V/24V automotive rails and accommodates load dump events. |
| Current Sense Threshold | 100mV ±3% at ISP–ISN; enables accurate, low-loss LED current regulation with minimal PCB layout sensitivity. |
| Switching Frequency Range | 250kHz to 2.5MHz; allows trade-off between efficiency (lower fSW) and component size (higher fSW). |
| PWM Dimming Ratio | 5000:1 true-color ratio; achieves flicker-free, high-fidelity dimming down to 0.02% duty cycle at 100Hz–120Hz. |
| Operating Junction Temp | –40°C to +125°C; qualified for under-hood automotive and industrial ambient environments. |
| Package Type | 16-lead plastic TSSOP; industry-standard footprint with exposed thermal pad (GND-connected) for thermal management. |
Pinout & Package
LT3517EFE#PBF is housed in a 16-lead plastic TSSOP package with exposed thermal pad (pin 17, GND). The package provides mechanical robustness and thermal performance suitable for high-current LED driver applications in space-constrained designs.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| VIN | Main input supply rail | Accepts 3V–30V input; requires local 2.2µF ceramic bypass capacitor to minimize high-frequency ripple and EMI. |
| 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 | 0–1V input scales LED current linearly (0–100%); clamped at 100mV sense threshold when ≥1V. |
| PWM | Digital dimming control | Active-low signal enabling 5000:1 PWM dimming; disables main switch and forces TG high to disconnect LED string. |
| SYNC | External clock input | Accepts 200kHz–3MHz CMOS clock; requires RT resistor set to 20% lower frequency for reliable synchronization. |
| FB | Voltage loop feedback | Regulates output voltage to 1.01V threshold; provides overvoltage protection and constant-voltage mode control. |
| SS | Soft-start timing | Capacitor-connected node controlling startup ramp rate; 0.1µF yields smooth start with minimal inrush current. |
| RT | Frequency programming | Resistor-to-GND sets oscillator frequency (250kHz–2.5MHz); must not be left floating or capacitive-loaded. |
| SW | Power switch drain | High dv/dt node; requires minimized trace area and adjacent ground plane to reduce EMI and switching losses. |
| TG | Top-gate PMOS driver | Inverted PWM output driving external PMOS; clamped to VISP – 7V to protect gate oxide of series disconnect FET. |
| ISP / ISN | High-side current sense inputs | Differential pair measuring voltage across external sense resistor; rail-to-rail operation supports wide LED string voltage range. |
| TGEN | PMOS driver enable | Logic-high (>1.5V) activates TG output; internal 40kΩ pull-down allows direct tie to GND to disable function. |
| VREF | 2.0V precision reference | Stable 2.0V ±2% output sourcing up to 100µA; used for CTRL biasing, resistor-divider references, or external circuitry. |
| VC | Error amplifier output | gm amplifier output (550µS) for loop compensation; RC network here stabilizes both current and voltage regulation loops. |
| GND | Signal and thermal ground | Exposed pad (pin 17) must be soldered to PCB ground plane with multiple thermal vias for junction temperature control. |
Key Features
| Feature | Design Value |
|---|---|
| True Color PWM™ dimming | 5000:1 ratio preserves color fidelity across dimming range by maintaining consistent LED forward voltage and thermal profile. |
| Integrated 1.5A/45V switch | Eliminates need for external high-voltage MOSFET in most LED string configurations up to 36W (24V × 1.5A). |
| Open LED protection | Automatic shutdown when ISP–ISN voltage exceeds threshold, preventing overvoltage damage to LEDs and driver. |
| PMOS gate driver (TG) | Enables fast, low-loss LED string disconnection during PWM off-time, preserving output capacitor charge and reducing recovery delay. |
| Adjustable frequency (250kHz–2.5MHz) | Allows optimization of inductor size (e.g., 6.8µH at 2MHz vs. 22µH at 250kHz) and EMI filtering requirements per application. |
| 100mV current sense threshold | Reduces power loss in sense resistor by 4× versus 400mV alternatives, improving efficiency especially at high LED currents. |
Applications
| Automotive Interior Lighting | Industrial Display Backlighting |
|---|---|
|
Use Scenario: LED dome lights, map lights, and footwell illumination in passenger vehicles with 12V/24V battery systems subject to load dump transients. IC Role / Device Role / Timing Role: Constant-current LED driver operating in buck mode, regulating 350mA–1A through multi-LED strings while surviving 40V transients. Use Value: Built-in 40V transient tolerance and open-LED protection eliminate need for external TVS diodes or fault monitoring circuits. |
Use Scenario: High-brightness LCD panel backlights in factory HMIs, medical displays, and outdoor kiosks requiring uniform luminance and flicker-free dimming. IC Role / Device Role / Timing Role: Boost-mode constant-current source delivering stable 100–300mA to white LED strings with 100Hz–120Hz PWM dimming. Use Value: 5000:1 True Color PWM™ ensures no visible color shift during dimming, critical for color-accurate human-machine interfaces. |
| Avionic Cabin Lighting | Barcode Scanner Illumination |
|
Use Scenario: FAA-certified LED lighting in commercial aircraft cabins where reliability, thermal stability, and EMI compliance are mandatory. IC Role / Device Role / Timing Role: Buck-boost topology driver powering 24V LED arrays from variable 18–32V avionics bus, with -40°C to +125°C operation. Use Value: Dual-loop regulation maintains precise current despite wide input variation and temperature drift, ensuring consistent light output over flight envelope. |
Use Scenario: Pulsed high-intensity illumination for CCD/CMOS barcode scanners requiring microsecond-level LED turn-on/off timing. IC Role / Device Role / Timing Role: Fast-response constant-current driver using PWM input and TG-controlled PMOS disconnect to achieve <2µs LED on/off transitions. Use Value: Integrated TG driver and stored VC state reduce PWM recovery time, enabling rapid successive scan pulses without current overshoot. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar LED driver applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LT3965EFE#PBF | Higher 40V switch rating, integrated PWM generator, I²C interface, but no analog CTRL pin or TG driver. | Better suited for digitally controlled multi-channel systems; lacks analog dimming and PMOS disconnect for ultra-fast PWM recovery. | Select when system-level digital control and channel synchronization outweigh need for analog dimming flexibility. |
| LM3409QMH/NOPB | 40V switch, adjustable current limit, no integrated reference or TG driver; requires external VREF and PMOS gate control. | Lower BOM cost but higher design complexity; lacks 100mV sense, True Color PWM, and open-LED protection. | Select for cost-sensitive, thermally relaxed applications where external compensation and discrete protection are acceptable. |
Compared with LT3517EFE#PBF, LT3965EFE#PBF adds digital control at the expense of analog dimming simplicity, while LM3409QMH/NOPB reduces integration to lower cost but increases layout and validation effort for robust LED current regulation.
Availability
LT3517EFE#PBF is available at Aetrix Electronics and suitable for automotive interior lighting, industrial display backlighting, and avionic cabin lighting requiring stable component supply, long-term lifecycle support, and guaranteed parametric performance across temperature extremes.
Supply support for LT3517EFE#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, 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 LT3517EFE#PBF belongs to ADI's Power by Linear™ LED driver product line, engineered specifically for high-reliability, high-dynamic-range illumination systems demanding precision current regulation, robust fault protection, and seamless dimming performance.
FAQ
What is the maximum input voltage rating for LT3517EFE#PBF during continuous operation?
The LT3517EFE#PBF supports continuous input operation from 3V to 30V. It tolerates nonrepetitive 40V transients for up to one second-critical for automotive load dump conditions. Exceeding 30V continuously risks exceeding thermal limits, especially at high ambient temperatures or high duty cycles. Always verify power dissipation using θJA = 40°C/W for the TSSOP package.
How does the LT3517EFE#PBF achieve 5000:1 PWM dimming without color shift?
The LT3517EFE#PBF achieves 5000:1 True Color PWM™ dimming by combining fast-switching capability (up to 2.5MHz), stored VC node state during PWM off-time, and integrated TG-driven PMOS LED disconnect. This prevents output capacitor discharge and eliminates current recovery delay, maintaining consistent LED junction temperature and forward voltage across the entire dimming range-preserving chromaticity.
Can LT3517EFE#PBF operate in buck, boost, and buck-boost modes with the same PCB layout?
No-LT3517EFE#PBF requires topology-specific component placement and routing. While the IC itself supports all three modes, each demands distinct inductor, diode, sense resistor, and feedback divider configurations. For example, buck mode places RSENSE on the high side of the LED string, whereas boost mode locates it on the input side. Shared layouts risk instability or failure to regulate.
What is the function of the TG pin on LT3517EFE#PBF, and how is it used?
The TG (Top Gate) pin on LT3517EFE#PBF is an inverted PWM output that drives the gate of an external PMOS transistor placed in series with the LED string. When PWM is low, TG goes high, turning off the PMOS and isolating the LED string-preventing output capacitor discharge and enabling near-instantaneous dimming recovery. TGEN must be pulled high to enable TG functionality.
Does LT3517EFE#PBF provide open-LED protection, and how does it work?
Yes, LT3517EFE#PBF includes built-in open-LED protection. When the ISP–ISN differential voltage exceeds the current sense threshold (e.g., due to broken LED string), the IC disables the main switch, halts switching, and pulls the TG pin high to disconnect the LED path. This prevents uncontrolled voltage rise at the FB node and protects downstream components from overvoltage stress.
LT3517EFE#PBF Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- True Color PWM™
- 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:
- 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-TSSOP-EP
LT3517EFE#PBF FAQ
1.How can I place an order for LT3517EFE#PBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LT3517EFE#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 LT3517EFE#PBF reliable?
The price and inventory of LT3517EFE#PBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LT3517EFE#PBF is usually 5 days.
3.What payment methods are accepted for LT3517EFE#PBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LT3517EFE#PBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LT3517EFE#PBF?
LT3517EFE#PBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LT3517EFE#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 LT3517EFE#PBF?
For technical support, including LT3517EFE#PBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LT3517EFE#PBF requirements.
6.How does Aetrix verify that LT3517EFE#PBF is sourced from the original manufacturer or authorized distributors?
All LT3517EFE#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 LT3517EFE#PBF meets industry standards.
7.What is the process for return or replacement of LT3517EFE#PBF?
All LT3517EFE#PBF units undergo pre-shipment inspection (PSI). If there is an issue with LT3517EFE#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 LT3517EFE#PBF part is unused and in its original packaging.
Return procedure for LT3517EFE#PBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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