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Analog Devices Inc. LT3956EUHE#TRPBF
- Part No.:
- LT3956EUHE#TRPBF
- Manufacturer:
- Analog Devices Inc.
- Category:
- LED Drivers
- Package:
- 36-WFQFN, 28 Leads, Exposed Pad
- Datasheet:
-
LT3956EUHE#TRPBF.pdf
- Description:
- IC LED DRVR RGLTR PWM 3.3A 36QFN
- Quantity:
- Payment:
- Shipping:
Inventory:9,897
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Product details
Overview
LT3956EUHE#TRPBF from Analog Devices (formerly Linear Technology) is a constant-current/constant-voltage DC/DC controller IC designed for high-power LED driving in boost, buck, buck-boost, SEPIC, and flyback topologies. It integrates an 84V/3.3A internal N-channel MOSFET, supports 4.5V–80V input, delivers up to 80V output, and enables true-color PWM dimming up to 3000:1. It is used in automotive headlamps, industrial lighting, and battery-powered LED systems.
For engineers reviewing the LT3956EUHE#TRPBF datasheet, LT3956EUHE#TRPBF pinout, LT3956EUHE#TRPBF application, or LT3956EUHE#TRPBF equivalent, key selection criteria include high-side current sensing capability, programmable switching frequency (100kHz–1MHz), open-LED and overvoltage protection, adjustable current threshold via CTRL pin, and thermal shutdown at 165°C - all critical for robust LED driver design and BOM optimization.
Technical Context
The LT3956EUHE#TRPBF employs a fixed-frequency, current-mode control architecture with internal slope compensation for stable operation across wide VIN (4.5V–80V) and VOUT (up to 80V) ranges. Its dual-loop regulation supports simultaneous or independent constant-current (via ISP/ISN high-side sensing) and constant-voltage (via FB pin) control, with seamless mode transition governed by VMODE status signaling.
It features integrated protection including ISP/ISN short-circuit detection (<3V common-mode), programmable UVLO with hysteresis on EN/UVLO, open-LED fault detection via FB loop monitoring, and overvoltage shutdown triggered when FB exceeds VFB + 60mV. The VC error amplifier output provides loop compensation flexibility, while PWMOUT drives external disconnect MOSFETs for load isolation during faults.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 4.5V to 80V - supports wide-range industrial and automotive battery inputs, including 12V/24V/48V systems with 80V transient tolerance. |
| Output Voltage Capability | Up to 80V - enables driving long LED strings in boost or SEPIC configurations without external HV FETs. |
| Internal Switch Rating | 84V VDS, 3.3A continuous - eliminates need for external high-voltage switch in many medium-power LED drivers. |
| Current Sense Threshold | 250mV nominal (adjustable 0–257mV via CTRL) - sets precise LED current with minimal power loss in sense resistor. |
| Switching Frequency Range | 100kHz to 1MHz (RT-programmable) - allows trade-off between efficiency, EMI, and external component size (inductor/capacitor). |
| Dimming Ratio | 3000:1 true-color PWM - preserves color consistency across full brightness range in high-end lighting applications. |
| Operating Junction Temp | –40°C to 125°C - qualified for under-hood automotive and industrial environments requiring extended thermal reliability. |
Pinout & Package
LT3956EUHE#TRPBF is housed in a thermally enhanced 36-lead (5mm × 6mm) plastic QFN package with two exposed pads: Pin 37 (GND) and Pin 38 (SW). The package supports high-power dissipation and requires soldering both exposed pads to PCB copper for thermal and electrical integrity.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| VIN | Main input supply rail | Accepts 4.5V–80V; must be bypassed with ≥0.22µF ceramic capacitor to PGND near the pin. |
| SW | Drain of internal N-MOSFET | Connects directly to inductor; exposed pad (Pin 38) must be soldered to thermal plane for current handling and heat dissipation. |
| ISP / ISN | High-side current sense inputs | Differential pair measuring LED string current; supports common-mode range up to 80V and short-circuit detection below 3V. |
| FB | Voltage feedback input | Regulates output voltage to 1.25V reference; also enables open-LED detection and overvoltage protection (FB > VFB + 60mV forces PWMOUT low). |
| CTRL | Current threshold adjustment | Programs ISP–ISN sense voltage from 0mV to 257mV; tied to VREF for default 250mV setting. |
| PWM | Digital dimming control | Active-low signal enabling/disabling switching; controls PWMOUT and stores VC state during idle for fast restart. |
| VMODE | Fault status indicator | Open-collector output pulled low when FB drops ≤ VFB – 50mV - signals open-LED or CV-mode takeover. |
| INTVCC | Internal LDO output | 7.15V regulated supply for gate driver and logic; requires 4.7µF local bypass; connect to VIN if VIN ≤ 7V. |
Key Features
| Feature | Design Value |
|---|---|
| High-side current sensing | Enables flexible topology support (boost/buck/buck-boost/SEPIC/flyback) without ground-referenced LED strings. |
| True-color PWM dimming | 3000:1 ratio with no color shift - achieved via precise timing control and dedicated PWMOUT driver for external disconnect FET. |
| Programmable undervoltage lockout | Accurate 1.22V falling threshold with user-defined hysteresis via external resistor divider on EN/UVLO pin. |
| Integrated short-circuit protection | Monitors ISP–ISN differential voltage <335mV when ISN <3V - prevents destructive currents during startup or output shorts in SEPIC designs. |
| Constant-voltage loop status pin | VMODE asserts low when FB falls ≤ VFB – 50mV - provides real-time indication of open-LED condition or CV-mode activation. |
Applications
| Automotive Headlamp Driver | Battery-Powered LED Lighting |
|---|---|
Use Scenario: High-brightness white LED headlamps in 12V/24V vehicles with cold-crank (4.5V) and load-dump (80V) transients. IC Role / Device Role / Timing Role: Constant-current controller regulating 370mA LED string in boost configuration; handles wide VIN range and provides PWM dimming synchronized to vehicle CAN bus commands. Use Value: 94% peak efficiency at 25W output ensures minimal thermal stress; integrated 84V switch eliminates external HV FET, reducing BOM count and layout complexity. | Use Scenario: Portable emergency lighting or solar-charged LED arrays requiring stable current delivery across varying battery SOC (10V–30V). IC Role / Device Role / Timing Role: Buck-mode constant-current regulator driving 10–20 LEDs; uses CTRL pin for analog dimming and temperature compensation via thermistor network. Use Value: Adjustable current threshold (0–257mV) enables precise dimming down to near-zero current; low shutdown IQ (<1µA) extends battery runtime in standby. |
| Industrial Machine Vision Lighting | LED-Based Battery Charger |
Use Scenario: High-intensity strobed illumination for inspection systems requiring microsecond-level flash timing and consistent lumen output. IC Role / Device Role / Timing Role: Fast-response constant-current source in buck-boost topology; PWM input triggers precise LED pulses; VMODE confirms open-circuit integrity before each flash. Use Value: 3000:1 PWM dimming enables calibrated intensity scaling; high-side sensing avoids ground loop interference in sensitive imaging electronics. | Use Scenario: Multi-cell Li-ion or lead-acid battery charger with CC/CV profile and LED status indicators. IC Role / Device Role / Timing Role: Dual-loop controller: ISP/ISN regulates charging current; FB regulates termination voltage; PWMOUT isolates LED load during overvoltage events. Use Value: Simultaneous CC/CV regulation eliminates need for separate charger IC; open-LED and overvoltage protections prevent damage to battery or LEDs during fault conditions. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar constant-current/constant-voltage LED driver applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LTC3783EFE#PBF | Requires external high-side N-MOSFET; no integrated switch; supports higher VIN (100V) and wider frequency range (50kHz–1MHz). | Better suited for >80V input or >3.3A output applications where thermal management favors discrete FETs. | Select LTC3783EFE#PBF when higher voltage/current headroom or discrete FET optimization is required; LT3956EUHE#TRPBF preferred for compact, integrated solutions up to 80V/3.3A. |
| LM3410XSD/NOPB | Single-switch buck-only controller; lower max VIN (42V); no CV regulation or VMODE status pin; simpler feature set. | Limited to low-to-mid power buck LED drivers without open-LED detection or multi-topology flexibility. | Choose LM3410XSD/NOPB for cost-sensitive, single-topology, sub-20W applications; LT3956EUHE#TRPBF offers broader functionality and higher integration for demanding designs. |
Compared with LTC3783EFE#PBF and LM3410XSD/NOPB, the LT3956EUHE#TRPBF uniquely combines integrated 84V/3.3A switching, dual-loop CC/CV control, high-side sensing, and comprehensive fault reporting (VMODE/PWMOUT) in a single QFN package - making it optimal for space-constrained, high-reliability LED driver designs requiring topology flexibility and robust protection.
Availability
LT3956EUHE#TRPBF is available at Aetrix Electronics and suitable for automotive lighting, industrial LED systems, and battery-powered portable lighting requiring stable component supply, long-term lifecycle support, and traceable sourcing.
Supply support for LT3956EUHE#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 semiconductors, formed through the acquisition of Linear Technology in 2017.
The LT3956EUHE#TRPBF belongs to ADI's Power by Linear™ portfolio of high-efficiency DC/DC controllers, specifically engineered for precision constant-current LED driving in harsh environments - emphasizing thermal robustness, fault resilience, and topology versatility.
FAQ
What is the maximum LED string voltage supported by the LT3956EUHE#TRPBF?
The LT3956EUHE#TRPBF supports output voltages up to 80V, enabling long LED strings in boost, SEPIC, or flyback configurations. This rating is defined by its internal switch breakdown voltage (84V) and validated across the full –40°C to 125°C junction temperature range. Applications exceeding 80V require external HV FETs or alternative controllers like the LTC3783.
How does the LT3956EUHE#TRPBF implement open-LED protection?
The LT3956EUHE#TRPBF detects open-LED conditions via the FB pin: when the FB voltage falls to VFB – 50mV (typical), the VMODE pin pulls low to signal the fault. If FB rises above VFB + 60mV (e.g., due to overvoltage), PWMOUT is driven low to disconnect the LED load. These functions operate independently of the current loop and are active across the full operating temperature range.
Can the LT3956EUHE#TRPBF be used in buck mode with high-side current sensing?
Yes - the LT3956EUHE#TRPBF supports buck-mode operation with high-side current sensing using ISP/ISN. In this configuration, the LED string connects between VIN and the switch node (SW), with the sense resistor placed between ISP and ISN on the high side. The datasheet Figure 3 confirms this arrangement, and the ISP common-mode range (2.9V–80V) accommodates typical buck-mode bias conditions.
What is the purpose of the VMODE pin on the LT3956EUHE#TRPBF?
The VMODE pin on the LT3956EUHE#TRPBF is an open-collector output that pulls low when the FB voltage drops to VFB – 50mV (typical), indicating either open-LED condition or constant-voltage loop dominance. It remains latched during PWM low periods and updates when PWM goes high. An external pull-up resistor (≤1mA) is required; VMODE provides real-time system-level fault status without additional monitoring circuitry.
Does the LT3956EUHE#TRPBF support analog dimming in addition to PWM?
Yes - the LT3956EUHE#TRPBF supports analog dimming via the CTRL pin, which adjusts the ISP–ISN current sense threshold from 0mV to 257mV. At CTRL = 2V, threshold is 250mV; at CTRL = 0.5V, it drops to ~100mV. For zero-current dimming, CTRL can be driven below 0.1V (threshold becomes negative), though accuracy degrades. This complements the 3000:1 true-color PWM dimming for hybrid brightness control.
LT3956EUHE#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):
- 80V
- Voltage - Output:
- 80V
- Current - Output / Channel:
- 3.3A (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)
LT3956EUHE#TRPBF FAQ
1.How can I place an order for LT3956EUHE#TRPBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LT3956EUHE#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 LT3956EUHE#TRPBF reliable?
The price and inventory of LT3956EUHE#TRPBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LT3956EUHE#TRPBF is usually 5 days.
3.What payment methods are accepted for LT3956EUHE#TRPBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LT3956EUHE#TRPBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LT3956EUHE#TRPBF?
LT3956EUHE#TRPBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LT3956EUHE#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 LT3956EUHE#TRPBF?
For technical support, including LT3956EUHE#TRPBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LT3956EUHE#TRPBF requirements.
6.How does Aetrix verify that LT3956EUHE#TRPBF is sourced from the original manufacturer or authorized distributors?
All LT3956EUHE#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 LT3956EUHE#TRPBF meets industry standards.
7.What is the process for return or replacement of LT3956EUHE#TRPBF?
All LT3956EUHE#TRPBF units undergo pre-shipment inspection (PSI). If there is an issue with LT3956EUHE#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 LT3956EUHE#TRPBF part is unused and in its original packaging.
Return procedure for LT3956EUHE#TRPBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
LT3956EUHE#TRPBF Tags
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