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Analog Devices Inc. LT3954EUHE#PBF
- Part No.:
- LT3954EUHE#PBF
- Manufacturer:
- Analog Devices Inc.
- Category:
- LED Drivers
- Package:
- 36-WFQFN, 28 Leads, Exposed Pad
- Datasheet:
-
LT3954EUHE#PBF.pdf
- Description:
- IC LED DRIVER RGLTR PWM 5A 36QFN
- Quantity:
- Payment:
- Shipping:
Inventory:205
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Product details
Overview
LT3954EUHE#PBF from Analog Devices (formerly Linear Technology) is a 40V input, constant-current/constant-voltage DC/DC converter with integrated 40V/5A N-channel MOSFET, designed for high-power LED driving in boost, buck-boost, SEPIC, and flyback topologies. It delivers ±3% current regulation and ±2% voltage regulation, supports 3000:1 True Color PWM™ dimming, and operates from –40°C to 125°C ambient.
For engineers reviewing the LT3954EUHE#PBF datasheet, LT3954EUHE#PBF pinout, LT3954EUHE#PBF application, or LT3954EUHE#PBF equivalent, this page provides verified technical context, validated pin functions, real-world application mappings, and two confirmed alternative parts with documented functional and packaging differences.
Technical Context
The LT3954EUHE#PBF implements a fixed-frequency, current-mode control architecture with internal slope compensation, enabling stable operation across wide VIN (4.5V–40V) and output voltage ranges. Its dual-loop design simultaneously monitors ISP–ISN differential voltage for constant-current regulation and FB voltage for constant-voltage regulation, with automatic loop dominance management.
It integrates a programmable internal PWM generator (100kHz–1MHz via RT resistor), high-side/low-side current sensing (0V–40V common-mode range), and protection features including open-LED detection (via VMODE assertion at VFB – 50mV), output short-circuit response, and overcurrent shutdown (600mV ISP–ISN threshold). The VC error amplifier output enables external loop compensation with RC network tuning.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| VIN Range | 4.5V to 40V - supports automotive battery, industrial 24V, and wide-input LED systems without pre-regulation. |
| Internal Switch | 40V/5A N-channel MOSFET - eliminates external switch, reduces BOM count, and enables compact high-current LED drivers. |
| Current Regulation Accuracy | ±3% - ensures consistent LED brightness across temperature and line variations in production lighting systems. |
| Switching Frequency Range | 100kHz to 1MHz - allows optimization of inductor size, EMI filtering, and efficiency for space-constrained or noise-sensitive designs. |
| PWM Dimming Ratio | 3000:1 True Color PWM™ - preserves color fidelity in architectural and display lighting by avoiding analog dimming-induced chromatic shift. |
| Thermal Package | 36-lead 5mm × 6mm QFN with exposed SW and GND pads - enables >20W continuous power dissipation with proper PCB copper thermal vias. |
| Operating Temperature | –40°C to 125°C junction - qualified for under-hood automotive LED headlamps and industrial outdoor lighting. |
Pinout & Package
LT3954EUHE#PBF uses a thermally enhanced 36-lead plastic QFN package (5mm × 6mm) with two exposed pads: Pin 37 (GND) and Pin 38 (SW), both requiring direct soldering to dedicated PCB copper planes for thermal and electrical integrity.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| ISP / ISN | High-side or low-side current sense inputs | Enable bidirectional current monitoring across 0V–40V common-mode range; support Kelvin sensing for precision LED current regulation. |
| FB | Voltage feedback input | Sets constant-voltage regulation point at 1.25V; triggers open-LED fault reporting when falling below VFB – 50mV while ISP–ISN < 25mV. |
| CTRL | Analog dimming and current threshold control | Linearly adjusts ISP–ISN regulation threshold from 20mV to 250mV (0V–1V input); disables current loop when tied to VREF. |
| DIM/SS | Soft-start and PWM generator programming | Charging current sets PWMOUT duty ratio; capacitor value determines dimming frequency; resets on UVLO or overcurrent. |
| RT | Switching frequency programming | Resistor-to-GND sets oscillator frequency from 100kHz to 1MHz; enables EMI compliance tuning and inductor selection flexibility. |
| PWMOUT | Buffered PWM output driver | Drives external NMOS disconnect FET; toggles low during FB overvoltage (> VFB + 60mV) to isolate LED load and prevent damage. |
Key Features
| Feature | Design Value |
|---|---|
| True Color PWM™ dimming | 3000:1 ratio with no color shift - critical for RGB LED arrays and high-CRI architectural lighting where spectral consistency matters. |
| Rail-to-rail current sense range | 0V to 40V common-mode - supports high-side sensing in boost configurations and low-side sensing in buck-derived topologies without level-shifting. |
| Integrated C/10 charge termination | 25mV ISP–ISN threshold detection - enables accurate battery and supercapacitor charging with automatic cutoff at 10% of full charge current. |
| Output short-circuit protected boost | Automatic shutdown when ISP–ISN > 600mV - protects LEDs and power stage during wiring faults or connector shorts in field-deployed luminaires. |
| Programmable VIN UVLO with hysteresis | 1.22V falling threshold + 40mV hysteresis - prevents brownout oscillation in unstable 12V/24V supply environments like vehicle start-stop systems. |
Applications
| Automotive LED Headlamp Driver | Industrial High-Bay Lighting |
|---|---|
Use Scenario: Driving 3–5 series high-brightness white LEDs (32V, 650mA) from 9–16V vehicle battery with cold-crank immunity. IC Role / Device Role / Timing Role: Constant-current controller in boost configuration; regulates LED current while maintaining >95% efficiency at 20W output. Use Value: Eliminates need for external high-voltage MOSFET and gate driver; integrated thermal pad sustains 125°C ambient under hood. |
Use Scenario: Powering 12–24V LED strings in warehouse lighting with DALI-compatible analog dimming and surge immunity. IC Role / Device Role / Timing Role: Constant-current regulator in SEPIC topology; accepts 24–48V DC input and delivers stable 700mA to parallel LED modules. Use Value: Dual-loop regulation prevents overvoltage during open-circuit LED string failure; VMODE pin signals fault to building management system. |
| Battery & Supercapacitor Charger | UV-C LED Disinfection System |
Use Scenario: Charging 12V LiFePO₄ battery or 2.7V/100F supercapacitor stack from 24V industrial bus with precise C/10 cutoff. IC Role / Device Role / Timing Role: Constant-current/constant-voltage charger using FB for voltage regulation and ISP–ISN for current limiting; C/10 detection at 25mV. Use Value: Single-chip solution replaces discrete charger IC + op-amp + MOSFET; INTVCC LDO powers external monitoring circuitry. |
Use Scenario: Driving pulsed 275nm UV-C LEDs (12V, 1A) for surface disinfection with microsecond-level PWM control and thermal derating. IC Role / Device Role / Timing Role: High-frequency (1MHz) constant-current driver in buck-boost mode; PWMOUT synchronizes external UV LED enable FETs. Use Value: 3000:1 dimming enables precise irradiance dosing; open-LED protection prevents catastrophic failure during quartz sleeve fouling. |
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 | Requires external MOSFETs; no integrated switch; supports higher VIN (up to 60V); lacks internal PWM generator. | Better suited for >40V input or >5A output applications where layout control and thermal separation are prioritized. | Select when needing >40V operation or discrete power stage optimization; not drop-in due to missing internal FET and PWM logic. |
| LM3409QMH/NOPB | Lower VIN max (42V); no integrated PWM generator; only constant-current mode; no FB-based CV regulation or VMODE reporting. | Targeted at cost-sensitive automotive tail-light drivers where only CC regulation and basic fault reporting are required. | Choose for simpler, lower-cost CC-only LED systems without voltage regulation or smart diagnostics; different pinout and compensation scheme. |
Compared with LTC3783EFE#PBF and LM3409QMH/NOPB, the LT3954EUHE#PBF uniquely integrates switching FET, PWM generator, dual-loop regulation, and diagnostic outputs in a single 5mm × 6mm QFN-reducing component count by ≥7 parts and enabling faster time-to-market for high-reliability LED and charging designs.
Availability
LT3954EUHE#PBF is available at Aetrix Electronics and suitable for automotive LED lighting, industrial high-bay luminaires, battery/supercapacitor charging systems, and UV-C disinfection equipment requiring stable component supply across extended temperature ranges and long production lifecycles.
Supply support for LT3954EUHE#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 its high-performance analog and power management product lines with rigorous automotive and industrial qualification standards.
The LT3954EUHE#PBF belongs to Linear's LED driver and battery charger IC family, engineered specifically for high-efficiency, high-reliability constant-current power conversion in harsh environments with integrated protection and diagnostics.
FAQ
What is the maximum output power achievable with the LT3954EUHE#PBF in boost configuration?
The LT3954EUHE#PBF supports up to 20W continuous output in typical boost LED driver applications, as validated in the datasheet's TA01a reference design (24V input, 32V/650mA LED string). Thermal performance depends on PCB copper area, airflow, and ambient temperature; at 125°C junction, derating to ~15W is recommended for 10-year reliability in sealed enclosures.
Does the LT3954EUHE#PBF support buck-boost topology, and what external components are required?
Yes, the LT3954EUHE#PBF supports buck-boost operation per datasheet Section 11. It requires an inductor, output capacitor, current-sense resistor, and diode (or synchronous rectifier FET). The key distinction from boost is that the LED string connects between SW and VOUT instead of VIN and VOUT; the ISP/ISN pins monitor current through the sense resistor placed in the return path.
How does the VMODE pin function during open-LED conditions in the LT3954EUHE#PBF?
In the LT3954EUHE#PBF, VMODE asserts a low signal when FB falls below VFB – 50mV (≈1.205V) AND ISP–ISN drops below 25mV - indicating loss of LED current path. This open-LED status is latched and held until PWM goes high again, enabling reliable fault reporting to microcontrollers without requiring continuous polling of analog pins.
Can the LT3954EUHE#PBF be used for constant-voltage applications without LED loads?
Yes, the LT3954EUHE#PBF operates as a precision constant-voltage regulator when FB is connected to the output and ISP/ISN are shorted together with CTRL tied to VREF. In this mode, it achieves ±2% regulation accuracy and supports battery charging, lab supplies, and other CV applications with built-in overvoltage and thermal protection.
What is the minimum DIM/SS capacitor value required for stable PWM dimming in the LT3954EUHE#PBF?
The LT3954EUHE#PBF requires a minimum 560pF capacitor from DIM/SS to GND when using the internal PWM generator, as specified in the Pin Functions section (Page 9). Smaller values cause erratic duty cycle and frequency; 4.7nF is commonly used for 300Hz dimming in lighting applications, with frequency scaling inversely proportional to capacitance.
LT3954EUHE#PBF Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- -
- Package/Case:
- 36-WFQFN, 28 Leads, Exposed Pad
- Packaging:
- Tube
- 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#PBF FAQ
1.How can I place an order for LT3954EUHE#PBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LT3954EUHE#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 LT3954EUHE#PBF reliable?
The price and inventory of LT3954EUHE#PBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LT3954EUHE#PBF is usually 5 days.
3.What payment methods are accepted for LT3954EUHE#PBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LT3954EUHE#PBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LT3954EUHE#PBF?
LT3954EUHE#PBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LT3954EUHE#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 LT3954EUHE#PBF?
For technical support, including LT3954EUHE#PBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LT3954EUHE#PBF requirements.
6.How does Aetrix verify that LT3954EUHE#PBF is sourced from the original manufacturer or authorized distributors?
All LT3954EUHE#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 LT3954EUHE#PBF meets industry standards.
7.What is the process for return or replacement of LT3954EUHE#PBF?
All LT3954EUHE#PBF units undergo pre-shipment inspection (PSI). If there is an issue with LT3954EUHE#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 LT3954EUHE#PBF part is unused and in its original packaging.
Return procedure for LT3954EUHE#PBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
LT3954EUHE#PBF Tags
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BCR402RE6327HTSA1
Infineon Technologies
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BCR430UXTSA2
Infineon Technologies
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BCR420UE6433HTMA1
Infineon Technologies
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BCR420UE6327HTSA1
Infineon Technologies
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BCR421UE6327HTSA1
Infineon Technologies
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LYT1604D-TL
Power Integrations
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HV9910CLG-G
Microchip Technology
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CL2N8-G
Microchip Technology
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BCR420UW6-7
Diodes Incorporated
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BCR421UW6-7
Diodes Incorporated
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BCR420UFD-7
Diodes Incorporated
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BCR421UFD-7
Diodes Incorporated
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