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Analog Devices Inc. LT3950EMSE#PBF
- Part No.:
- LT3950EMSE#PBF
- Manufacturer:
- Analog Devices Inc.
- Category:
- LED Drivers
- Package:
- 16-TFSOP (0.118", 3.00mm Width) Exposed Pad
- Datasheet:
-
LT3950EMSE#PBF.pdf
- Description:
- IC LED DRV RGLTR PWM 1.5A 16MSOP
- Quantity:
- Payment:
- Shipping:
Inventory:1,002
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Product details
Overview
LT3950EMSE#PBF from Analog Devices is a 60V, 1.5A monolithic LED driver IC with integrated DMOS switch, supporting boost/SEPIC/buck/buck-boost topologies. It delivers ±2% LED current regulation, 128:1 internal exponential-scale PWM dimming, and dual constant-current/constant-voltage (CC/CV) control for automotive lighting systems requiring robust open/short LED protection.
For engineers reviewing the LT3950EMSE#PBF datasheet, LT3950EMSE#PBF pinout, LT3950EMSE#PBF application, or LT3950EMSE#PBF equivalent, key selection criteria include its AEC-Q100 qualification, 300kHz–2MHz programmable switching frequency, internal spread spectrum EMI reduction, PMOS gate driver for external PWM dimming, and 16-lead MSOP package with exposed thermal pad.
Technical Context
The LT3950EMSE#PBF implements a constant-frequency, current-mode DC/DC controller with dual-loop regulation: an ISP/ISN-based current-sense amplifier for LED current control and an FB-based voltage amplifier for output overvoltage protection. Its error amplifiers feature transconductances of 60µS (LED current) and 500µS (FB), enabling stable CC/CV transition during open-LED events.
It integrates a 7-bit ADC-driven internal PWM generator mapping linear 0.2V–1.2V input to exponential duty ratios (0.78%–100%), preserving dimming resolution across 20000:1 external PWM range. The SYNC/SPRD pin supports both spread-spectrum modulation (25% depth) and external clock synchronization without layout changes.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 3V to 60V - supports wide automotive battery transients (e.g., cold-crank to load-dump) |
| Switch Rating | 1.5A, 60V DMOS - enables direct high-current LED string drive without external FET in most boost/SEPIC designs |
| LED Current Accuracy | ±2% - ensures consistent brightness across temperature and unit-to-unit variation in display backlighting |
| Dimming Resolution | 128:1 internal exponential scale - maintains perceptible brightness steps from 0.1% to 100% LED current |
| Switching Frequency | 300kHz to 2MHz - allows trade-off between inductor size (2MHz) and efficiency (300kHz) |
| Thermal Rating | –40°C to +125°C junction - meets extended temperature requirements for under-hood automotive lighting |
| AEC-Q100 Grade | Grade 1 (LT3950E) - qualified for passenger compartment and exterior lighting per automotive reliability standards |
Pinout & Package
LT3950EMSE#PBF is housed in a 16-lead plastic MSOP package with exposed thermal pad (Pin 17 = GND), optimized for thermal dissipation in space-constrained automotive modules. The exposed pad must be soldered to PCB ground plane for proper thermal and electrical performance.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| ISP / ISN | High-side Kelvin current sense inputs | Measure VISP–VISN to regulate LED current; tolerate up to 60V common-mode voltage |
| FB | Output voltage feedback node | Triggers CV mode at 1.2V; asserts FAULT at 1.3V (OV) or <300mV (short LED) |
| CTRL | Analog dimming control | Linearly scales LED current from 0% to 100% as voltage ramps from 0.2V to 1.2V |
| PWM | Internal exponential PWM generator input | Maps 0.2V–1.2V to 0.78%–100% duty ratio with logarithmic step resolution |
| PWMTG | External PMOS gate driver | Drives gate between VISP and VISP–7.5V to disconnect LED during dimming/faults |
| SYNC/SPRD | Frequency control interface | Tied to INTVCC for spread-spectrum EMI reduction; driven by external clock for synchronization |
| FAULT | Open-drain fault indicator | Pulls low for open LED, short LED, overvoltage, or overcurrent events; requires 100kΩ pull-up |
Key Features
| Feature | Design Value |
|---|---|
| Integrated 60V/1.5A DMOS switch | Eliminates external high-voltage switch in most 10W LED drivers, reducing BOM count and layout area |
| 128:1 internal exponential PWM dimming | Preserves human-perceivable brightness resolution across full 0.1%–100% dimming range without microcontroller intervention |
| Dual CC/CV regulation with fault reporting | Automatically transitions to voltage regulation during open-LED faults while signaling via FAULT pin |
| Programmable 300kHz–2MHz switching | Enables optimization for EMI (lower fSW) or compact magnetics (higher fSW) without changing topology |
| AEC-Q100 Grade 1 qualification | Validated for automotive ambient temperatures (–40°C to +125°C) and lifetime reliability per stress test protocols |
Applications
| Automotive Headlamp Control | Avionic Cabin Lighting |
|---|---|
Use Scenario: High-brightness LED headlamps requiring adaptive beam shaping and dynamic dimming in vehicles. IC Role / Device Role / Timing Role: Constant-current LED driver with fast open/short LED fault detection and PWM dimming for DRL, low-beam, and high-beam modes. Use Value: ±2% current accuracy ensures consistent lumen output across temperature; AEC-Q100 qualification guarantees operation under automotive vibration and thermal cycling. |
Use Scenario: Dimmable cabin lighting in commercial aircraft with strict EMI and reliability requirements. IC Role / Device Role / Timing Role: CC/CV LED driver supporting 20000:1 external PWM dimming and spread-spectrum switching to meet DO-160E radiated emissions limits. Use Value: Internal spread spectrum reduces peak EMI by >10dB; 128:1 exponential dimming enables smooth, flicker-free cabin ambiance control. |
| Industrial Display Backlighting | Heavy-Duty Vehicle Lighting |
Use Scenario: High-resolution LCD backlights in industrial HMIs requiring uniform brightness and long-term stability. IC Role / Device Role / Timing Role: Boost-mode LED driver with precise analog dimming via CTRL pin and overvoltage protection for capacitor aging compensation. Use Value: CTRL pin enables seamless analog dimming without PWM artifacts; FB-based CV mode prevents overvoltage damage during LED aging or temperature drift. |
Use Scenario: Exterior lighting (tail lamps, turn signals) on construction and agricultural equipment operating in harsh environments. IC Role / Device Role / Timing Role: SEPIC-mode LED driver handling wide input (6V–32V) and providing fault-tolerant open/short LED reporting. Use Value: 60V input rating withstands 24V system load-dump transients; FAULT pin provides diagnostic signal for vehicle CAN bus integration. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar LED driver applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LT3965EMSE#PBF | 4-channel, 40V, 150mA per channel; I²C programmable; no internal switch | Designed for multi-string RGBW backlighting with digital control, not single-string high-current driving | Select when multi-string independent dimming and digital configuration are required over single-channel 1.5A capability |
| LM3409QMY/NOPB | 40V, 5A external switch driver; no integrated FET; no internal PWM generator; no AEC-Q100 grade | Requires external MOSFET and MCU for dimming; suited for cost-sensitive non-automotive LED systems | Select when higher peak current (>1.5A) or lower BOM cost justifies added design complexity and lack of automotive qualification |
Compared with LT3950EMSE#PBF, LT3965EMSE#PBF offers digital channel control but lacks integrated power switch and automotive qualification, while LM3409QMY/NOPB provides higher current headroom but requires external components and does not support internal exponential dimming or AEC-Q100 compliance.
Availability
LT3950EMSE#PBF is available at Aetrix Electronics and suitable for automotive lighting, avionic cabin systems, industrial display backlighting, and heavy-duty vehicle exterior lighting requiring stable component supply and long-term production continuity.
Supply support for LT3950EMSE#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 is a global leader in high-performance analog, mixed-signal, and digital signal processing semiconductors, serving industrial, automotive, communications, and healthcare markets.
The LT3950 product line delivers highly integrated, AEC-Q100-qualified LED drivers for automotive and aerospace lighting applications where reliability, precision dimming, and fault resilience are critical.
FAQ
What topology configurations does the LT3950EMSE#PBF support?
The LT3950EMSE#PBF supports boost, SEPIC, buck, and buck-boost topologies through external component selection. Its internal 60V/1.5A DMOS switch and dual-loop CC/CV regulation enable flexible implementation across these configurations without changing the IC. The LT3950EMSE#PBF datasheet provides reference designs for each mode, including component values and layout guidelines for EMI reduction.
How does the internal exponential PWM dimming work on the LT3950EMSE#PBF?
The LT3950EMSE#PBF uses a 7-bit ADC to convert the linear 0.2V–1.2V voltage on the PWM pin into exponentially spaced duty ratios (0.78%–100%). Each 7.8mV step changes the duty ratio by a fixed multiplicative factor-e.g., near 10%, a step yields ~0.4% absolute change, while near 100%, it yields ~4%-preserving perceptual resolution. This eliminates need for external microcontroller-based logarithmic lookup tables in the LT3950EMSE#PBF.
What protection features are built into the LT3950EMSE#PBF?
The LT3950EMSE#PBF integrates LED open, short, overvoltage, and overcurrent protection. It asserts the open-drain FAULT pin for all four conditions: open LED (FB <1.2V while current <10% full-scale), short LED (FB <300mV), overvoltage (FB >1.3V), and overcurrent (VISP–VISN >700mV). PWMTG disconnects the LED string during faults, and soft-start resets automatically after fault clearance.
Can the LT3950EMSE#PBF operate without an external PMOS for PWM dimming?
Yes, the LT3950EMSE#PBF supports analog dimming via the CTRL pin (0.2V–1.2V) and internal exponential PWM dimming via the PWM pin without any external PMOS. The PWMTG pin may be left unconnected if external PWM dimming is not required. However, the external PMOS is necessary only when hardware-level load disconnection during dimming/faults is needed-e.g., to prevent residual current in capacitive LED strings.
What is the purpose of the exposed thermal pad on the LT3950EMSE#PBF MSOP package?
The exposed thermal pad (Pin 17) on the LT3950EMSE#PBF MSOP package is electrically and thermally connected to GND. It must be soldered to a PCB copper pour for effective heat dissipation and to maintain junction temperature within –40°C to +125°C limits. Thermal resistance θJA is specified at 40°C/W only when the pad is properly soldered; omitting this connection risks thermal shutdown or accelerated parametric drift in the LT3950EMSE#PBF.
LT3950EMSE#PBF Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- -
- Package/Case:
- 16-TFSOP (0.118", 3.00mm Width) Exposed Pad
- 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):
- 60V
- Voltage - Output:
- 1.2V ~ 60V
- Current - Output / Channel:
- 1.5A
- Frequency:
- 300kHz ~ 2MHz
- Dimming:
- PWM
- Applications:
- Backlight
- Operating Temperature:
- -40°C ~ 125°C (TA)
- Grade:
- Automotive
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 16-MSOP-EP
LT3950EMSE#PBF FAQ
1.How can I place an order for LT3950EMSE#PBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LT3950EMSE#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 LT3950EMSE#PBF reliable?
The price and inventory of LT3950EMSE#PBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LT3950EMSE#PBF is usually 5 days.
3.What payment methods are accepted for LT3950EMSE#PBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LT3950EMSE#PBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LT3950EMSE#PBF?
LT3950EMSE#PBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LT3950EMSE#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 LT3950EMSE#PBF?
For technical support, including LT3950EMSE#PBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LT3950EMSE#PBF requirements.
6.How does Aetrix verify that LT3950EMSE#PBF is sourced from the original manufacturer or authorized distributors?
All LT3950EMSE#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 LT3950EMSE#PBF meets industry standards.
7.What is the process for return or replacement of LT3950EMSE#PBF?
All LT3950EMSE#PBF units undergo pre-shipment inspection (PSI). If there is an issue with LT3950EMSE#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 LT3950EMSE#PBF part is unused and in its original packaging.
Return procedure for LT3950EMSE#PBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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