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Analog Devices Inc. LT3954EUHE#TRPBF
- Part No.:
- LT3954EUHE#TRPBF
- Manufacturer:
- Analog Devices Inc.
- Category:
- LED Drivers
- Package:
- 36-WFQFN, 28 Leads, Exposed Pad
- Datasheet:
-
LT3954EUHE#TRPBF.pdf
- Description:
- IC LED DRIVER RGLTR PWM 5A 36QFN
- Quantity:
- Payment:
- Shipping:
Inventory:2,370
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Product details
Overview
LT3954EUHE#TRPBF from Analog Devices (formerly Linear Technology) is a 40V input, constant-current/constant-voltage DC/DC converter IC optimized for high-power LED driving in boost, SEPIC, buck-boost, and flyback topologies. It integrates a 40V/5A N-channel MOSFET switch, internal PWM dimming generator, rail-to-rail current sense amplifier (0V–40V), and ±3% current regulation accuracy. It delivers up to 20W output in typical boost LED applications with 95% efficiency.
For engineers reviewing the LT3954EUHE#TRPBF datasheet, LT3954EUHE#TRPBF pinout, LT3954EUHE#TRPBF application, or LT3954EUHE#TRPBF equivalent, key selection criteria include its 4.5V–40V input range, programmable 100kHz–1MHz switching frequency, 3000:1 True Color PWM™ dimming capability, high-side/low-side current sensing flexibility, and integrated open-LED and short-circuit protection - all in a thermally enhanced 36-lead 5mm × 6mm QFN package.
Technical Context
The LT3954EUHE#TRPBF employs a fixed-frequency, current-mode control architecture with slope compensation, enabling stable operation across wide VIN (4.5V–40V) and VOUT ranges. Its dual-loop design supports simultaneous or independent constant-current (via ISP/ISN) and constant-voltage (via FB) regulation, with seamless mode transition signaled by the VMODE pin.
It features an internal 7.85V LDO (INTVCC) powering gate drivers and logic, a programmable soft-start via DIM/SS capacitor, and fault management including overcurrent (600mV ISP–ISN threshold), overvoltage (FB + 60mV), thermal shutdown (>165°C), and open-LED detection (FB < VFB – 50mV & ISP–ISN < 25mV).
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 4.5V to 40V - supports automotive battery, industrial 24V, and wide-input LED systems without external pre-regulation. |
| Switch Rating | 40V/5A internal N-MOSFET - eliminates external high-side switch in most boost/SEPIC LED drivers up to ~20W. |
| Current Regulation Accuracy | ±3% - ensures consistent LED brightness across temperature and line/load variations. |
| PWM Dimming Ratio | 3000:1 True Color PWM™ - preserves color fidelity in high-end architectural and display lighting. |
| Switching Frequency Range | 100kHz to 1MHz (programmable via RT resistor) - enables optimization of EMI, efficiency, and magnetics size. |
| Current Sense Range | Rail-to-rail 0V to 40V - allows high-side or low-side sensing in any topology without level-shifting circuitry. |
| Shutdown Current | <1µA - meets ultra-low-power standby requirements in battery-powered or energy-conscious systems. |
Pinout & Package
LT3954EUHE#TRPBF is housed in a thermally enhanced 36-lead plastic QFN package (5mm × 6mm), featuring two exposed pads: Pin 37 (GND) and Pin 38 (SW), both requiring direct soldering to PCB copper planes for thermal and electrical integrity.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| GND (Pins 4, 24, Exposed Pad 37) | Power and signal reference ground | Primary return path for INTVCC, VC, FB, CTRL; exposed pad must be soldered to large GND plane for thermal dissipation. |
| SW (Pins 8, 9, 20, 21, Exposed Pad 38) | Drain of internal 40V/5A N-MOSFET | High-current switching node; exposed pad must connect to SW copper pour to minimize inductance and thermal resistance. |
| ISP / ISN | High-side or low-side current sense inputs | Differential pair measuring LED current; supports 0V–40V common-mode range - enables flexible placement across load or sense resistor. |
| FB | Voltage feedback input for CV regulation | Regulates output voltage to 1.25V reference; triggers open-LED detection when below VFB – 50mV while ISP–ISN < 25mV. |
| CTRL | Analog dimming and current threshold control | Sets ILED = (CTRL – 0.1V)/(4 × RSENSE) for 0V–1V; clamps at full-scale 250mV above 1.2V for precise analog dimming. |
| DIM/SS | Soft-start timing and PWM generator programming | Charging current sets PWMOUT duty cycle; capacitor value defines soft-start time and dimming frequency (e.g., 47nF → ~300Hz). |
| RT | Switching frequency programming | Resistor to GND sets oscillator frequency from 100kHz (95.3kΩ) to 1MHz (8.87kΩ); critical for EMI compliance and efficiency tuning. |
| VMODE | Open-LED / CV-mode status indicator | Open-drain output pulled low when FB > VFB – 50mV AND ISP–ISN < 25mV - signals transition from CC to CV regulation. |
Key Features
| Feature | Design Value |
|---|---|
| Integrated 40V/5A power switch | Reduces BOM count and layout complexity in medium-power LED drivers; eliminates need for external high-voltage MOSFET and driver. |
| True Color PWM™ dimming (3000:1) | Preserves LED chromaticity at low duty cycles - essential for museum lighting, medical displays, and premium signage where color shift is unacceptable. |
| Rail-to-rail current sense (0V–40V) | Enables direct high-side sensing in boost configurations or low-side sensing in buck-derived topologies without op-amp level shifters. |
| Programmable switching frequency (100kHz–1MHz) | Allows trade-off between inductor size (higher fSW → smaller L) and conduction losses (lower fSW → higher efficiency at high current). |
| Output short-circuit protected boost | Automatically disables SW and pulls PWMOUT low during output short - prevents damage to LEDs, inductor, and IC under fault conditions. |
| C/10 indication for battery charging | Uses ISP–ISN voltage threshold (25mV typ.) to signal end-of-charge in Li-ion or supercapacitor applications - simplifies charger state machine design. |
Applications
| Automotive Headlamp Drivers | Industrial High-Bay LED Lighting |
|---|---|
Use Scenario: Driving 3–5 series high-brightness white LEDs (36V–60V) from 12V/24V vehicle battery with dynamic headlight leveling and adaptive beam shaping. IC Role / Device Role / Timing Role: Constant-current LED driver with programmable dimming, open-circuit detection, and thermal foldback - operates as primary power stage in headlamp ECU. Use Value: Enables single-chip solution for AHB (Adaptive Driving Beam) compliance with 3000:1 dimming depth and fast transient response to camera-based scene analysis. |
Use Scenario: Powering 100W+ LED arrays in warehouse, factory, or outdoor area lighting using 24V–48V DC distribution rails. IC Role / Device Role / Timing Role: High-efficiency boost LED controller supporting DALI-2 or 0–10V analog dimming interfaces - functions as core current regulator in modular LED driver architecture. Use Value: Delivers >95% peak efficiency and ±3% current accuracy across 40°C–85°C ambient, reducing thermal management cost and extending LED lifetime. |
| Battery & Supercapacitor Chargers | UV-C LED Disinfection Systems |
Use Scenario: Charging 2–4 series Li-ion cells or 10–50F supercapacitors from 12V/24V sources with C/10 termination and voltage limiting. IC Role / Device Role / Timing Role: Constant-current/constant-voltage charger controller with programmable charge profile - replaces discrete charger ICs in portable medical or IoT power banks. Use Value: Uses FB and ISP–ISN loops to implement precise CC/CV charging; C/10 detection (25mV threshold) provides reliable end-of-charge signaling without external comparators. |
Use Scenario: Driving pulsed UV-C LEDs (275nm, 10–50W) for surface or air disinfection with precise dose control and thermal derating. IC Role / Device Role / Timing Role: High-reliability, high-current LED driver with fast PWM dimming and overtemperature protection - serves as pulse generator in germicidal irradiation modules. Use Value: Supports microsecond-level PWM pulses with 3000:1 ratio to deliver exact UV dose (J/cm²); thermal shutdown (>165°C) prevents LED degradation during high-duty-cycle operation. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar LED driver applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LT3761EUHE#TRPBF | Lacks integrated PWM generator; requires external PWM source for dimming; no DIM/SS pin or True Color PWM™ capability. | Better suited for analog-dimming-only or externally synchronized systems; not recommended for standalone high-ratio PWM dimming. | Select LT3954EUHE#TRPBF when self-contained 3000:1 PWM dimming and integrated soft-start are required. |
| LM3409QMHX/NOPB | Lower max input (42V vs 40V), no internal PWM generator, no VMODE or C/10 features; ±5% current accuracy vs ±3%. | Designed for cost-sensitive automotive LED tail lamps; lacks open-LED reporting and CV regulation robustness for charger use. | Choose LT3954EUHE#TRPBF for applications needing tighter regulation, integrated diagnostics, or dual CC/CV functionality. |
Compared with LT3761EUHE#TRPBF and LM3409QMHX/NOPB, the LT3954EUHE#TRPBF offers superior integration (on-chip PWM generator, VMODE status, C/10 charging signal), tighter current regulation (±3%), and broader topology support - making it optimal for high-fidelity LED lighting and multi-function power conversion where board space and feature count are critical.
Availability
LT3954EUHE#TRPBF is available at Aetrix Electronics and suitable for automotive headlamp drivers, industrial high-bay LED lighting, and battery/supercapacitor charging systems requiring stable component supply, long-term lifecycle support, and guaranteed traceable sourcing.
Supply support for LT3954EUHE#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 technologies, formed through the acquisition of Linear Technology in 2017.
The LT3954EUHE#TRPBF belongs to ADI's Power by Linear™ portfolio of high-efficiency, high-reliability LED drivers and battery chargers, designed specifically for demanding applications in automotive lighting, industrial illumination, and energy storage systems.
FAQ
What is the maximum output power achievable with the LT3954EUHE#TRPBF in a boost configuration?
The LT3954EUHE#TRPBF supports up to 20W output in typical boost LED applications, as validated in the datasheet's "95% Efficiency 20W Boost LED Driver" reference design. This assumes VIN ≥ 9V, proper thermal management (exposed SW/GND pads soldered to copper), and optimized layout. At lower input voltages (<9V), derating is required per the datasheet's "20W LED String (current derated for VIN < 9V)" note.
Does the LT3954EUHE#TRPBF support both high-side and low-side current sensing?
Yes, the LT3954EUHE#TRPBF supports rail-to-rail current sensing from 0V to 40V on the ISP and ISN pins. This allows direct high-side sensing (e.g., between LED anode and boost inductor) or low-side sensing (e.g., between LED cathode and GND) without external amplifiers or level shifters - a key advantage for flexible topology implementation.
How does the VMODE pin function in the LT3954EUHE#TRPBF, and what triggers its assertion?
The VMODE pin on the LT3954EUHE#TRPBF is an open-drain output that asserts (pulls low) when two conditions occur simultaneously: (1) FB voltage exceeds VFB – 50mV (≈1.205V), and (2) the ISP–ISN differential falls below 25mV (typical). This indicates transition from constant-current to constant-voltage regulation - useful for open-LED detection in LED drivers or end-of-charge signaling in battery chargers.
Can the LT3954EUHE#TRPBF be used for battery charging applications, and what features enable this?
Yes, the LT3954EUHE#TRPBF is explicitly designed for battery and supercapacitor charging. Key enablers include dual-loop CC/CV regulation, C/10 charge termination detection (using 25mV ISP–ISN threshold), FB overvoltage protection, and programmable soft-start via DIM/SS. Its ±3% current accuracy and wide input range make it suitable for Li-ion, lead-acid, and supercapacitor charging circuits.
What is the purpose of the DIM/SS pin on the LT3954EUHE#TRPBF, and how does it affect operation?
The DIM/SS pin on the LT3954EUHE#TRPBF serves dual roles: (1) soft-start timing control - an external capacitor sets ramp-up time during startup; and (2) PWM dimming signal generation - its charging current programs the duty cycle and frequency of the internal PWM generator (e.g., 47nF yields ~300Hz). It also resets during UVLO, overcurrent, or thermal faults to ensure safe restart behavior.
LT3954EUHE#TRPBF Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- -
- Package/Case:
- 36-WFQFN, 28 Leads, Exposed Pad
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Active
- Type:
- DC DC Regulator
- Topology:
- Flyback, SEPIC, Step-Down (Buck), Step-Up (Boost)
- Internal Switch(s):
- Yes
- Number of Outputs:
- 1
- Voltage - Supply (Min):
- 4.5V
- Voltage - Supply (Max):
- 40V
- Voltage - Output:
- -
- Current - Output / Channel:
- 5A (Switch)
- Frequency:
- 100kHz ~ 1MHz
- Dimming:
- Analog, PWM
- Applications:
- -
- Operating Temperature:
- -40°C ~ 125°C (TJ)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 36-QFN (5x6)
LT3954EUHE#TRPBF FAQ
1.How can I place an order for LT3954EUHE#TRPBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LT3954EUHE#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 LT3954EUHE#TRPBF reliable?
The price and inventory of LT3954EUHE#TRPBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LT3954EUHE#TRPBF is usually 5 days.
3.What payment methods are accepted for LT3954EUHE#TRPBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LT3954EUHE#TRPBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LT3954EUHE#TRPBF?
LT3954EUHE#TRPBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LT3954EUHE#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 LT3954EUHE#TRPBF?
For technical support, including LT3954EUHE#TRPBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LT3954EUHE#TRPBF requirements.
6.How does Aetrix verify that LT3954EUHE#TRPBF is sourced from the original manufacturer or authorized distributors?
All LT3954EUHE#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 LT3954EUHE#TRPBF meets industry standards.
7.What is the process for return or replacement of LT3954EUHE#TRPBF?
All LT3954EUHE#TRPBF units undergo pre-shipment inspection (PSI). If there is an issue with LT3954EUHE#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 LT3954EUHE#TRPBF part is unused and in its original packaging.
Return procedure for LT3954EUHE#TRPBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
LT3954EUHE#TRPBF Tags
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CL2N8-G
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