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Analog Devices Inc. LT3741EUF#PBF
- Part No.:
- LT3741EUF#PBF
- Manufacturer:
- Analog Devices Inc.
- Category:
- DC DC Switching Controllers
- Package:
- 20-WFQFN Exposed Pad
- Datasheet:
-
LT3741EUF#PBF.pdf
- Description:
- IC REG CTRLR BUCK 20QFN
- Quantity:
- Payment:
- Shipping:
Inventory:2,293
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Product details
Overview
LT3741EUF#PBF from Analog Devices (formerly Linear Technology) is a fixed-frequency synchronous step-down DC/DC controller designed for high-precision constant-current and constant-voltage regulation up to 20A output. It features average current-mode control, ±6% current regulation accuracy, ±1.5% voltage regulation accuracy, and supports 6V–36V input with output down to 0V (up to VIN – 2V). It is used in supercapacitor charging and industrial current-source applications requiring extreme short-circuit protection.
For engineers reviewing the LT3741EUF#PBF datasheet, LT3741EUF#PBF pinout, LT3741EUF#PBF application, or LT3741EUF#PBF equivalent, key selection criteria include its dual analog CTRL1/CTRL2 current programming interface, thermal current derating capability, 20-lead 4mm × 4mm QFN package with exposed GND pad, and ability to source/sink inductor current - distinguishing it from the LT3741-1 variant.
Technical Context
The LT3741EUF#PBF implements average current-mode control using internal gm amplifiers (475 µA/V for current loop, 850 µA/V for voltage loop) and a 2V buffered reference (±1% over temperature). Its dual-control architecture allows real-time current limiting via CTRL1 (0–1.5V, clamped) and thermal derating via CTRL2, with common-mode lockout ensuring operation only within 0–2V below VIN.
It integrates high-side (2.3Ω pull-up / 1.3Ω pull-down) and low-side (2.3Ω pull-up / 1.0Ω pull-down) gate drivers, programmable 200kHz–1MHz switching via RT resistor or external SYNC signal, and cycle-by-cycle overcurrent protection triggered at VSENSE+–VSENSE− = 51mV + 23mV offset. Soft-start uses 11µA charging current into external capacitor on SS pin.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 6V to 36V - supports wide industrial input rails including 12V, 24V, and 36V systems without external pre-regulation. |
| Output Current Accuracy | ±6% - enables precise current sourcing/sinking for supercap charging and LED driver-class applications. |
| Voltage Regulation Accuracy | ±1.5% - ensures stable output voltage under load transients and line variations, critical for battery-like sources. |
| Switching Frequency Range | 200kHz to 1MHz - adjustable via RT resistor or external clock on SYNC pin for EMI optimization and inductor size trade-offs. |
| CTRL1 Input Range | 0V to 1.5V (clamped) - maps linearly to 0–20A regulated output current via external sense resistor (e.g., 5mΩ → 20A). |
| Shutdown Quiescent Current | <1µA - enables ultra-low-power standby in always-on industrial or energy-harvesting systems. |
| Package | 20-lead 4mm × 4mm QFN with exposed thermal pad - provides low θJA = 37°C/W for high-current thermal management. |
Pinout & Package
LT3741EUF#PBF uses a thermally enhanced 20-lead plastic QFN (4mm × 4mm) with exposed GND pad (Pin 21), rated for –40°C to +125°C junction temperature. The exposed pad must be soldered to PCB for thermal and electrical performance.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| EN/UVLO (Pin 1) | Enable & Undervoltage Lockout Input | Turns on internal bias at 1.55V; full shutdown at ~0.5V; 130mV hysteresis enables programmable UVLO thresholds. |
| VREF (Pin 2) | 2V Buffered Reference Output | Supplies up to 500µA for CTRL1/CTRL2 divider networks; improves current-setting accuracy and noise immunity. |
| CTRL2 (Pin 3) | Thermal Derating Control Input | Reduces regulated current when thermally constrained; lower of CTRL1/CTRL2 sets final current limit. |
| GND (Pins 4,11,14,21) | Ground Return | Multiple ground connections and exposed pad minimize ground bounce and improve current-sense accuracy. |
| CTRL1 (Pin 5) | Main Current Setpoint Input | 0–1.5V analog input determines high-level regulated current; internally clamped to prevent overrange errors. |
| SS (Pin 6) | Soft-Start Timing Node | 11µA internal current charges external capacitor to ramp regulated current gradually during startup. |
| FB (Pin 7) | Voltage Feedback & OVP Input | 1.21V reference for output voltage regulation; triggers 13µs OVP shutdown if FB exceeds 1.5V. |
| SENSE+ (Pin 8) | Current Sense Inverting Input | Connects to high-side of external sense resistor; forms error amplifier input with SENSE– for average current loop. |
| SENSE– (Pin 9) | Current Sense Non-Inverting Input | Sinks reference current from CTRL1/CTRL2 path; completes current-sense differential pair with SENSE+. |
| VC (Pin 10) | Current Loop Compensation | Connects to RC network (e.g., 20kΩ + 2nF) to stabilize average current-mode control loop. |
| RT (Pin 12) | Frequency Setting Input | Resistor to GND sets fSW; 60µA current limit defines max frequency (~2MHz if shorted, but not recommended). |
| SYNC (Pin 13) | External Clock Synchronization | Accepts external clock; RT should be set for 20% lower internal frequency to avoid jitter or loss of sync. |
| HG (Pin 15) | High-Side Gate Driver Output | Drives external N-channel MOSFET gate; 2.3Ω pull-up / 1.3Ω pull-down enables fast switching with low shoot-through risk. |
| SW (Pin 16) | Switch Node | Connects high-side drain, low-side source, and inductor; floating node referenced to CBOOT for high-side drive. |
| CBOOT (Pin 17) | Floating High-Side Supply | 5V regulated supply for HG driver; requires Schottky diode from VCC_INT to charge bootstrap capacitor. |
| LG (Pin 18) | Low-Side Gate Driver Output | Drives external N-channel MOSFET gate; 2.3Ω pull-up / 1.0Ω pull-down optimized for low-side conduction losses. |
| VCC_INT (Pin 19) | Internal 5V Regulator Output | Powers internal circuits and charges CBOOT; current-limited to 50mA; disable by shutdown or VIN < 6V. |
| VIN (Pin 20) | Main Power Input | 6–36V supply input; requires local 4.7µF low-ESR ceramic bypass capacitor to GND for stability. |
Key Features
| Feature | Design Value |
|---|---|
| Dual analog current control (CTRL1 + CTRL2) | Enables simultaneous precision current setting and thermal derating without microcontroller intervention. |
| Average current-mode topology | Provides inherent current limiting, stable operation across wide output voltage range (0V to VIN – 2V), and immunity to duty-cycle limitations. |
| Source-and-sink capability | Supports bidirectional inductor current flow - essential for supercapacitor charging/discharging and regenerative loads. |
| Accurate 1.21V FB reference with OVP | Ensures tight voltage regulation and fast 13µs overvoltage shutdown to protect downstream components. |
| Integrated 5V VCC_INT regulator | Eliminates need for external bias supply; powers internal logic, gate drivers, and CBOOT charging circuitry. |
Applications
| Supercapacitor Charging | Industrial Constant-Current Source |
|---|---|
|
Use Scenario: Rapid charging of 10–100F supercapacitors from 12V/24V bus to 2.7V–5.5V with controlled inrush and thermal management. IC Role / Device Role / Timing Role: Primary current-regulating controller managing both charge current and voltage transition phases. Use Value: ±6% current accuracy prevents overcharge; CTRL2-based thermal foldback avoids capacitor overheating during high-current pulses. |
Use Scenario: Precision 0–20A current source for electroplating, LED test fixtures, or sensor excitation in factory automation. IC Role / Device Role / Timing Role: Fixed-frequency synchronous buck controller operating in constant-current mode with analog setpoint inputs. Use Value: Wide 0V–(VIN–2V) output compliance enables true zero-voltage sourcing; 20A capability eliminates need for paralleling controllers. |
| High-Reliability Short-Circuit Protection | Programmable Dual-Mode Power Supply |
|
Use Scenario: Power delivery to mission-critical loads where instantaneous fault response (<100ns) and cycle-by-cycle current limiting are mandatory. IC Role / Device Role / Timing Role: Current-mode controller enforcing hard current limit at 51mV + 23mV sense threshold with no soft-start delay. Use Value: Eliminates reliance on external current-limit ICs; built-in OCP responds faster than typical PMICs or discrete solutions. |
Use Scenario: Lab-grade bench supply supporting both CC and CV modes with front-panel analog voltage control and thermal monitoring. IC Role / Device Role / Timing Role: Dual-loop (current + voltage) controller accepting independent analog inputs for current setpoint and voltage setpoint. Use Value: Seamless transition between CC and CV modes without mode-switching artifacts; SS pin enables smooth startup ramp. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar constant-current step-down controller applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LTC3776 | Single-ended current-mode controller; no SENSE– current sink; supports only sourcing; no CTRL2 thermal input. | Lacks bidirectional current capability and thermal derating path; suitable only for unidirectional CC loads. | Select LTC3776 only when sink capability and thermal foldback are unnecessary and board space permits larger TSSOP-20 package. |
| LT3741EUF-1#PBF | Same pinout and package; omits sink capability and CTRL2 input; simplified version optimized for parallel operation. | Cannot regulate sinking current or support thermal derating; intended for multi-phase designs where current sharing dominates. | Choose LT3741EUF-1#PBF only for multi-phase constant-current arrays where individual thermal control is managed externally. |
Compared with LTC3776 and LT3741EUF-1#PBF, the LT3741EUF#PBF uniquely delivers bidirectional current control, integrated thermal derating, and full 0V-to-(VIN–2V) output compliance - making it irreplaceable in supercapacitor and regenerative load applications.
Availability
LT3741EUF#PBF is available at Aetrix Electronics and suitable for supercapacitor charging, industrial constant-current sources, and high-reliability short-circuit protected power supplies requiring stable component supply across extended temperature ranges.
Supply support for LT3741EUF#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 (ADI) is a global leader in high-performance analog, mixed-signal, and power management semiconductors, formed through the acquisition of Linear Technology in 2017.
The LT3741 product line was developed by Linear Technology specifically for high-accuracy, high-current constant-current and constant-voltage DC/DC conversion in industrial, automotive, and energy-storage applications - with emphasis on robustness, thermal intelligence, and analog programmability.
FAQ
What is the maximum output current supported by the LT3741EUF#PBF?
The LT3741EUF#PBF supports up to 20A regulated output current, determined by the external sense resistor value and CTRL1 voltage (e.g., 5mΩ with 1.5V on CTRL1 yields 20A). This rating assumes proper thermal design using the exposed pad and appropriate MOSFET selection per the datasheet guidelines.
Does the LT3741EUF#PBF support both sourcing and sinking current?
Yes, the LT3741EUF#PBF supports bidirectional inductor current flow - enabling both sourcing and sinking - unlike the LT3741-1 family. This capability is intrinsic to its average current-mode architecture and is confirmed in the device description, block diagram, and typical applications section of the LT3741 datasheet.
How does thermal derating work on the LT3741EUF#PBF?
Thermal derating on the LT3741EUF#PBF is implemented via the CTRL2 pin: an analog voltage applied to CTRL2 sets a secondary current limit, and the lower of CTRL1 and CTRL2 voltages determines the final regulated current. This allows direct analog interfacing with NTC thermistors or DAC outputs for real-time thermal foldback.
What is the function of the SENSE– pin on the LT3741EUF#PBF?
The SENSE– pin on the LT3741EUF#PBF serves as the non-inverting input of the average current-mode error amplifier and sinks reference current derived from CTRL1 or CTRL2. It completes the differential sense pair with SENSE+, enabling accurate measurement of voltage drop across the external sense resistor regardless of common-mode level.
Can the LT3741EUF#PBF operate with 0V output voltage?
Yes, the LT3741EUF#PBF supports output voltages down to 0V (within its specified output voltage range of 0V to VIN – 2V), enabled by its average current-mode control architecture and dedicated current regulation loop - making it suitable for supercapacitor discharge and zero-bias current-source applications.
LT3741EUF#PBF Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- -
- Package/Case:
- 20-WFQFN Exposed Pad
- Packaging:
- Tube
- Product Status:
- Active
- Output Type:
- Transistor Driver
- Function:
- Step-Down
- Output Configuration:
- Positive
- Topology:
- Buck
- Number of Outputs:
- 1
- Output Phases:
- 1
- Voltage - Supply (Vcc/Vdd):
- 6V ~ 36V
- Frequency - Switching:
- 200kHz ~ 1MHz
- Duty Cycle (Max):
- -
- Synchronous Rectifier:
- Yes
- Clock Sync:
- Yes
- Serial Interfaces:
- -
- Control Features:
- Enable, Frequency Control, Soft Start
- Operating Temperature:
- -40°C ~ 125°C (TJ)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 20-QFN (4x4)
LT3741EUF#PBF FAQ
1.How can I place an order for LT3741EUF#PBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LT3741EUF#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 LT3741EUF#PBF reliable?
The price and inventory of LT3741EUF#PBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LT3741EUF#PBF is usually 5 days.
3.What payment methods are accepted for LT3741EUF#PBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LT3741EUF#PBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LT3741EUF#PBF?
LT3741EUF#PBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LT3741EUF#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 LT3741EUF#PBF?
For technical support, including LT3741EUF#PBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LT3741EUF#PBF requirements.
6.How does Aetrix verify that LT3741EUF#PBF is sourced from the original manufacturer or authorized distributors?
All LT3741EUF#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 LT3741EUF#PBF meets industry standards.
7.What is the process for return or replacement of LT3741EUF#PBF?
All LT3741EUF#PBF units undergo pre-shipment inspection (PSI). If there is an issue with LT3741EUF#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 LT3741EUF#PBF part is unused and in its original packaging.
Return procedure for LT3741EUF#PBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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