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Analog Devices Inc. LT3519IMS#PBF
- Part No.:
- LT3519IMS#PBF
- Manufacturer:
- Analog Devices Inc.
- Category:
- LED Drivers
- Package:
- 16-TFSOP (0.118", 3.00mm Width)
- Datasheet:
-
LT3519IMS#PBF.pdf
- Description:
- IC LED DRV RGLTR PWM 16MSOP
- Quantity:
- Payment:
- Shipping:
Inventory:3,168
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Product details
Overview
LT3519IMS#PBF from Analog Devices (formerly Linear Technology) is a fixed-frequency 400kHz step-up DC/DC LED driver IC with integrated 45V/750mA low-side switch and Schottky diode. It supports constant-current and constant-voltage regulation, rail-to-rail current sense (0V–45V), programmable undervoltage lockout, and open-LED fault detection. It is designed for automotive and industrial LED lighting systems requiring robust transient protection (40V) and high dimming ratio.
For engineers reviewing the LT3519IMS#PBF datasheet, LT3519IMS#PBF pinout, LT3519IMS#PBF application, or LT3519IMS#PBF equivalent, this page delivers verified technical context, real-world operating parameters, validated alternative parts, and design-critical package and pin-level details - all specific to the LT3519IMS#PBF variant (400kHz, –40°C to 125°C, MSOP-16).
Technical Context
The LT3519IMS#PBF implements current-mode control with internal compensation and dual-loop regulation: voltage feedback via FB pin (1.22V reference) and rail-to-rail current sense via ISP/ISN pins. Its error amplifier selects between loops based on which demands lower peak switch current, enabling seamless transition between constant-current (LED drive) and constant-voltage (open-LED protection) modes.
It features a dedicated OPENLED open-collector status pin asserting when FB falls within ~60mV of 1.22V, indicating LED disconnection. Dimming is supported via external PWM input (up to 3000:1 True Color PWM™) and analog control via CTRL pin (0.1V–2.0V, linearly scaling current sense threshold from 100mV to 250mV).
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Switching Frequency | 400kHz - enables compact magnetics and EMI filtering while balancing efficiency and thermal performance in automotive LED boost designs. |
| Internal Switch Rating | 45V VDS, 750mA ISW - supports LED strings up to ~38V output with margin for transients; eliminates need for external MOSFET in many 12V/24V automotive applications. |
| Integrated Schottky Diode | 0.8V forward drop at 500mA - reduces BOM count and PCB area vs discrete diode solutions; enables self-contained boost topology without external rectifier. |
| Current Sense Range | Rail-to-rail 0V–45V across ISP/ISN - allows flexible placement of sense resistor in high-side, low-side, or floating configurations (e.g., buck, SEPIC, buck-boost). |
| CTRL Pin Threshold | Adjustable 100mV–250mV sense voltage - enables precise analog dimming and fine-tuned current programming (e.g., 100mA ±1% with 1% RSENSE). |
| Open LED Detection | FB threshold offset of –60mV (typ.) - provides reliable fault reporting without additional comparators; requires FB divider design to keep normal VFB ≤ 1.1V. |
| UVLO Hysteresis | Programmable via SHDN/UVLO pin with 2.2μA internal pull-down - allows custom turn-on/turn-off thresholds (e.g., 6.2V off / 8.2V on) for battery voltage monitoring. |
Pinout & Package
LT3519IMS#PBF is housed in a 16-lead plastic MSOP package (3mm × 4.9mm, 0.5mm pitch) with exposed pad for thermal dissipation. The package is rated for –40°C to 125°C junction temperature and features four GND pins (1, 8, 9, 16) for low-impedance grounding and improved thermal performance.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| GND (1, 8, 9, 16) | Power and signal ground reference | Four dedicated ground connections minimize ground bounce and improve thermal conduction; must be tied to solid GND plane. |
| OPENLED (2) | Open-collector fault status output | Pulls low when FB ≥ (1.22V – 60mV); requires external pull-up; latched during PWM low phase for stable fault reporting. |
| PWM (3) | Switch enable/disable control | Low disables oscillator and main switch; internal pull-down; tie to VREF if unused to prevent false shutdown. |
| SHDN/UVLO (4) | Shutdown and input undervoltage detection | 1.22V falling threshold with programmable hysteresis; sub-μA bias current above threshold ensures low quiescent power. |
| VIN (5) | Main input supply (3V–30V continuous) | Must be bypassed with ≥1μF ceramic capacitor placed adjacent to pin; withstands 40V transients for automotive load-dump immunity. |
| SW (6) | Switch node connection | Connects to inductor; high dV/dt node - minimize trace length/area to reduce EMI and switching losses. |
| ANODE (7) | Internal Schottky anode terminal | Connects to inductor in boost mode; ties to cathode of external diode in buck/buck-boost configurations. |
| ISP (11) | Current sense positive input | Non-inverting input of rail-to-rail current sense amplifier; bias current increases with VISP–VISN; keep away from SW node. |
| ISN (12) | Current sense negative input | Inverting input of current sense amplifier; forms Kelvin pair with ISP for accurate RSENSE measurement. |
| FB (13) | Voltage feedback input | Regulates to 1.22V; used for CV mode or open-LED detection; never leave floating - tie to GND if unused. |
| CTRL (14) | Current threshold adjustment | Sets VISP–VISN threshold from 100mV to 250mV; 50nA bias current enables high-impedance DAC or resistor divider interface. |
| VREF (15) | 2.0V precision reference output | Supplies up to 100μA; used to bias CTRL, PWM, or external circuitry; 0.04%/V line regulation ensures stability over input range. |
| CATHODE (10) | Internal Schottky cathode terminal | Connects to LED anode in boost mode; ties to inductor in buck mode; shares current path with internal diode. |
Key Features
| Feature | Design Value |
|---|---|
| True Color PWM™ dimming | Up to 3000:1 ratio at 120Hz - preserves LED color fidelity across full dimming range without low-frequency flicker or hue shift. |
| Multi-topology support | Operates in boost, SEPIC, buck-boost, or buck mode - enables single IC reuse across diverse LED string voltages and input conditions (e.g., 6V–30V automotive). |
| Integrated Schottky diode | Eliminates external diode, reducing component count by one and saving ~2mm² PCB area in typical boost layout. |
| Rail-to-rail current sense | 0V–45V common-mode range - permits sense resistor placement on either side of LED string or in series with high-voltage outputs without level-shifting. |
| Open LED protection with status pin | Hardware-based fault detection and reporting via OPENLED pin - removes need for external comparator or microcontroller polling in safety-critical lighting. |
| Internal compensation | Reduces external components to only RSENSE, feedback resistors, inductor, and input/output capacitors - accelerates design cycle and improves production yield. |
Applications
| Automotive Headlamp Driver | Industrial Panel Backlight |
|---|---|
Use Scenario: Driving 38V white LED string from 12V vehicle battery with load-dump immunity and thermal derating. IC Role / Device Role / Timing Role: Constant-current LED driver with 400kHz switching, integrated Schottky, and open-LED fault reporting via OPENLED pin. Use Value: Enables single-chip solution meeting AEC-Q100 Grade 1 temp range (–40°C to 125°C) and ISO 7637-2 pulse 5a transient requirements without external TVS or diode. | Use Scenario: Powering 16V, 150mA LED array in factory HMI panel with variable input (6V–24V) and analog dimming via 0–10V control signal. IC Role / Device Role / Timing Role: Buck-boost LED controller regulating current via ISP/ISN with CTRL pin interfaced to DAC for smooth 100:1 analog dimming. Use Value: Eliminates need for separate voltage regulator and current source; rail-to-rail sense allows direct sensing on LED cathode side, simplifying layout and improving accuracy. |
| Commercial Signage Power Supply | Emergency Exit Light Driver |
Use Scenario: Boosting 24V input to drive 24V, 150mA LED module in outdoor digital signage with 3000:1 PWM dimming for daylight visibility control. IC Role / Device Role / Timing Role: Fixed-frequency boost converter using ANODE/CATHODE pins and internal Schottky; PWM pin driven by microcontroller at 120Hz. Use Value: Achieves >92% efficiency at 12V input while maintaining color consistency across full brightness range - critical for brand-color accuracy in advertising displays. | Use Scenario: Reliable 9V, 500mA LED driver for battery-backed emergency lighting, requiring undervoltage lockout and open-circuit fault detection. IC Role / Device Role / Timing Role: Buck-mode LED controller with SHDN/UVLO pin programmed for 7V turn-on/6V turn-off and OPENLED pin wired to system fault indicator. Use Value: Guarantees fail-safe operation: automatically disables output below safe battery voltage and signals LED failure before backup runtime is compromised. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar LED driver applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LTC3783EMS#PBF | 4-switch synchronous buck-boost controller (no integrated switch or diode); requires external MOSFETs and gate drivers. | Higher efficiency (>95%) and power scalability (up to 10A), but larger BOM and layout complexity; no integrated fault pin like OPENLED. | Select when >4W output power, higher efficiency, or wide-input (4V–36V) buck-boost is required; not drop-in for LT3519IMS#PBF layouts. |
| MAX16820ATG+T | 400kHz boost LED driver with 40V/1.2A switch; no integrated Schottky; uses external diode; 1.25V FB reference. | Higher current capability and wider VIN range (4.5V–28V), but lacks rail-to-rail current sense and OPENLED status pin; different pinout and compensation scheme. | Select when driving >750mA LEDs or needing higher input transient tolerance; requires redesign of sense network and fault reporting circuitry. |
Compared with LTC3783EMS#PBF and MAX16820ATG+T, the LT3519IMS#PBF offers the lowest component count for <4W automotive LED applications due to its integrated switch and Schottky diode, while providing unique diagnostic features (OPENLED, rail-to-rail sense) not matched by either alternative - making it optimal for cost-sensitive, space-constrained, and safety-aware designs.
Availability
LT3519IMS#PBF is available at Aetrix Electronics and suitable for automotive headlamps, industrial HMIs, commercial signage, and emergency lighting systems requiring stable component supply, AEC-Q100-compliant temperature operation, and long-term lifecycle availability.
Supply support for LT3519IMS#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 and maintains full product support, datasheets, and application engineering for all Linear parts including the LT3519 family.
The LT3519IMS#PBF belongs to Linear's high-reliability LED driver product line, engineered specifically for automotive and industrial lighting where robustness, integrated protection, and minimal external components are critical design requirements.
FAQ
What is the switching frequency of the LT3519IMS#PBF?
The LT3519IMS#PBF operates at a fixed 400kHz switching frequency. This value is inherent to the LT3519 variant (as opposed to LT3519-1 at 1MHz or LT3519-2 at 2.2MHz) and is factory-trimmed - no external components adjust it. The 400kHz frequency balances inductor size, efficiency, and EMI in automotive LED boost applications, and is confirmed in the Electrical Characteristics table on page 3 of the official datasheet (3519fa).
Does the LT3519IMS#PBF include an integrated Schottky diode?
Yes, the LT3519IMS#PBF integrates a Schottky diode with 0.8V forward drop at 500mA and 4μA leakage at 24V (per page 3, Electrical Characteristics). This diode connects internally between the ANODE and CATHODE pins, eliminating the need for an external rectifier in boost configurations. Its inclusion is explicitly stated in the device description, features list, and pin function definitions - confirming it is present in the LT3519IMS#PBF variant.
What is the operating temperature range for the LT3519IMS#PBF?
The LT3519IMS#PBF is specified for a junction temperature range of –40°C to 125°C. This is the "I" grade (Industrial), confirmed in the Order Information table on page 2 of the datasheet, where LT3519IMS#PBF is listed with "–40°C to 125°C" under Temperature Range. All electrical characteristics marked with "l" apply across this full range, including FB regulation voltage, UVLO thresholds, and switch current limit.
How does open-LED detection work on the LT3519IMS#PBF?
The LT3519IMS#PBF uses its FB pin and OPENLED pin for hardware-based open-LED detection. When the FB voltage rises to within ~60mV of its 1.22V regulation threshold (i.e., ≥1.16V), the OPENLED pin pulls low. This occurs only when the LED string opens and the voltage loop takes control - provided the FB divider is designed so that normal operation keeps VFB ≤ 1.1V. The behavior is documented in the PIN FUNCTIONS section (page 6) and TYPICAL PERFORMANCE CHARACTERISTICS (Figure G11).
Can the LT3519IMS#PBF be used in buck configuration?
Yes, the LT3519IMS#PBF supports buck-mode LED driving, as demonstrated in Typical Application TA04a (page 15) and TA06a (page 17) of the datasheet. In buck mode, the ANODE pin connects to the input, CATHODE to the inductor, and the LED string is placed between inductor and ground. The rail-to-rail current sense (ISP/ISN) and dual-loop regulation allow stable constant-current operation - confirmed by efficiency plots and waveform captures showing 500mA output with 90% efficiency at 20V input.
LT3519IMS#PBF Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- -
- Package/Case:
- 16-TFSOP (0.118", 3.00mm Width)
- Packaging:
- Tube
- Product Status:
- Active
- Type:
- DC DC Regulator
- Topology:
- SEPIC, 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:
- 750mA (Switch)
- Frequency:
- 400kHz
- Dimming:
- Analog, PWM
- Applications:
- Lighting
- Operating Temperature:
- -40°C ~ 125°C (TJ)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 16-MSOP
LT3519IMS#PBF FAQ
1.How can I place an order for LT3519IMS#PBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LT3519IMS#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 LT3519IMS#PBF reliable?
The price and inventory of LT3519IMS#PBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LT3519IMS#PBF is usually 5 days.
3.What payment methods are accepted for LT3519IMS#PBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LT3519IMS#PBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LT3519IMS#PBF?
LT3519IMS#PBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LT3519IMS#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 LT3519IMS#PBF?
For technical support, including LT3519IMS#PBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LT3519IMS#PBF requirements.
6.How does Aetrix verify that LT3519IMS#PBF is sourced from the original manufacturer or authorized distributors?
All LT3519IMS#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 LT3519IMS#PBF meets industry standards.
7.What is the process for return or replacement of LT3519IMS#PBF?
All LT3519IMS#PBF units undergo pre-shipment inspection (PSI). If there is an issue with LT3519IMS#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 LT3519IMS#PBF part is unused and in its original packaging.
Return procedure for LT3519IMS#PBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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