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Analog Devices Inc. LT3741EUF-1#PBF
- Part No.:
- LT3741EUF-1#PBF
- Manufacturer:
- Analog Devices Inc.
- Category:
- DC DC Switching Controllers
- Package:
- 20-WFQFN Exposed Pad
- Datasheet:
-
LT3741EUF-1#PBF.pdf
- Description:
- IC REG CTRLR BUCK 20QFN
- Quantity:
- Payment:
- Shipping:
Inventory:3,827
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Product details
Overview
LT3741EUF-1#PBF from Analog Devices (formerly Linear Technology) is a fixed-frequency synchronous step-down DC/DC controller optimized for high-accuracy constant-current and constant-voltage regulation up to 20A. It features average current-mode control, ±6% current regulation accuracy, ±1.5% voltage regulation accuracy, and supports input voltages from 6V to 36V with output voltage range up to (VIN – 2V). It is used in super-capacitor charging and industrial power supplies requiring precise current limiting and extreme short-circuit protection.
For engineers reviewing the LT3741EUF-1#PBF datasheet, LT3741EUF-1#PBF pinout, LT3741EUF-1#PBF application, or LT3741EUF-1#PBF equivalent, key selection considerations include its dual analog CTRL1/CTRL2 current programming interface, thermally enhanced 4mm × 4mm QFN package with exposed ground pad, 200kHz–1MHz programmable switching frequency, and ability to source/sink current - distinguishing it from the LT3741EUF#PBF variant.
Technical Context
The LT3741EUF-1#PBF implements average current-mode control with internal gm amplifiers (475 µA/V for current loop, 850 µA/V for voltage loop), enabling independent regulation of inductor current and output voltage. Its unique topology supports bidirectional current flow - sourcing and sinking - making it suitable for active load control and regenerative applications.
It integrates a 2V buffered reference (VREF), 11µA soft-start current source (SS), and precision EN/UVLO with 1.55V falling threshold and 130mV hysteresis. The CTRL2 pin enables thermal derating of regulated current, while FB pin provides 1.21V feedback reference and overvoltage lockout at 1.5V (13µs shutdown).
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% - ensures tight current regulation for LED drivers, battery charging, and super-capacitor formation. |
| Voltage Regulation Accuracy | ±1.5% - maintains stable output under varying load and line conditions for CV-sensitive loads. |
| Switching Frequency Range | 200kHz to 1MHz - adjustable via RT resistor or external SYNC signal, enabling EMI optimization and size/cost trade-offs. |
| Current Sense Threshold | 51mV typical (SENSE+ to SENSE–) - sets full-scale current with external sense resistor; enables low-loss, high-precision sensing. |
| Thermal Shutdown | 163°C with 8°C hysteresis - protects against sustained overload or poor heatsinking in enclosed industrial environments. |
| Shutdown Quiescent Current | <1µA - minimizes system standby power loss in always-on or battery-backed applications. |
Pinout & Package
LT3741EUF-1#PBF is housed in a thermally enhanced 20-lead (4mm × 4mm) plastic QFN package with exposed ground pad (Pin 21), requiring soldering to PCB for thermal and electrical integrity. θJA = 37°C/W.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| EN/UVLO (Pin 1) | Enable / Undervoltage Lockout Input | Active-high enable with 1.55V threshold and 130mV hysteresis; controls startup sequencing and brownout protection. |
| VREF (Pin 2) | 2V Buffered Reference Output | Supplies up to 0.5mA; used to bias CTRL1/CTRL2 via resistor dividers for accurate current programming. |
| CTRL2 (Pin 3) | Thermal Derating Control Input | Analog input (0–1.5V) that dynamically reduces regulated current based on temperature sensor feedback. |
| GND (Pins 4,11,14,21) | Ground Reference / Exposed Pad | Four dedicated GND pins plus exposed pad - mandatory for thermal dissipation and noise immunity in high-current designs. |
| CTRL1 (Pin 5) | Primary Current Setpoint Input | Analog input (0–1.5V) setting high-level regulated current; clamped internally to prevent overrange operation. |
| SS (Pin 6) | Soft-Start Timing Node | Charged by 11µA current source; controls ramp rate of regulated current during startup to limit inrush. |
| FB (Pin 7) | Voltage Feedback / Overvoltage Sense | 1.21V reference point for output voltage regulation; triggers 13µs shutdown if voltage exceeds 1.5V. |
| SENSE+ (Pin 8) | Current Sense Inverting Input | Connects to high-side of external sense resistor; forms differential pair with SENSE– for current error amplification. |
| SENSE– (Pin 9) | Current Sense Non-Inverting Input | Connects to low-side of sense resistor; sinks reference current from CTRL1/CTRL2 to establish current setpoint. |
| 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-ground sets switching frequency; 40kΩ yields ~1MHz, 200kΩ yields ~200kHz. |
| SYNC (Pin 13) | External Clock Synchronization | Accepts TTL/CMOS clock; requires internal oscillator set 20% slower than SYNC frequency for reliable locking. |
| HG (Pin 15) | High-Side Gate Driver Output | Drives external N-channel MOSFET gate; 2.3Ω pull-up / 1.3Ω pull-down impedance enables fast switching. |
| SW (Pin 16) | Switch Node | Connects high-side drain, low-side source, and inductor; critical for layout due to high dV/dt and EMI. |
| CBOOT (Pin 17) | Floating High-Side Supply | Charged via Schottky diode from VCC_INT; provides isolated 5V rail for high-side driver bootstrap operation. |
| LG (Pin 18) | Low-Side Gate Driver Output | Drives external N-channel MOSFET gate; 2.3Ω pull-up / 1.0Ω pull-down impedance supports high-efficiency synchronous rectification. |
| VCC_INT (Pin 19) | Internal 5V Regulator Output | Supplies CBOOT capacitor and internal circuitry; current-limited to 50mA; disable during shutdown. |
| VIN (Pin 20) | Main Power Input | Accepts 6–36V input; requires local 4.7µF low-ESR ceramic bypass capacitor for stability and noise suppression. |
Key Features
| Feature | Design Value |
|---|---|
| Bidirectional current capability | Supports both sourcing and sinking of regulated current - essential for active load testing and regenerative braking circuits. |
| Dual analog current programming (CTRL1 + CTRL2) | Enables dynamic current derating via external thermistor or microcontroller DAC, improving reliability under thermal stress. |
| Accurate 1.21V FB reference with overvoltage lockout | Ensures robust CV regulation and prevents damage during open-load or transient overvoltage events. |
| Integrated 2V reference with 0.5mA drive | Eliminates need for external reference IC when generating CTRL1/CTRL2 bias voltages, reducing BOM count and layout area. |
| Programmable soft-start with 11µA current source | Allows precise control of current ramp rate using standard capacitor values (e.g., 100nF → 1.1ms ramp), preventing inrush-induced voltage droop. |
| Thermally enhanced QFN with exposed GND pad | Delivers 37°C/W junction-to-ambient thermal resistance - critical for maintaining <125°C junction temperature at 20A continuous operation. |
Applications
| Super-Capacitor Charging | Industrial Constant-Current Source |
|---|---|
|
Use Scenario: Charging large-value super-capacitors (e.g., 50F, 2.7V) from 12V or 24V bus with controlled inrush and precise end-of-charge current taper. IC Role / Device Role / Timing Role: Acts as constant-current sink during charge phase and transitions to constant-voltage mode near full charge; uses FB-based OVP to terminate charging safely. Use Value: Enables full utilization of super-capacitor capacity while avoiding overvoltage stress, extending cycle life beyond 500,000 cycles. |
Use Scenario: Providing stable 15A–20A current to electroplating baths, semiconductor test fixtures, or laser diode bias circuits. IC Role / Device Role / Timing Role: Functions as high-accuracy current regulator with ±6% tolerance across temperature and line variations; CTRL2 enables real-time current reduction during thermal alarms. Use Value: Replaces bulky linear supplies with >94% efficiency, reducing heat sink size and system power consumption by >70%. |
| LED Driver for High-Power Arrays | Extreme Short-Circuit Protected Power Supply |
|
Use Scenario: Driving multi-string, high-brightness LED arrays (e.g., 100W+ street lighting) requiring stable current despite forward voltage drift. IC Role / Device Role / Timing Role: Regulates average inductor current to match LED string requirements; uses SENSE+/SENSE– differential sensing to reject common-mode noise from long traces. Use Value: Maintains consistent lumen output over ambient temperature range (–40°C to +85°C) without optical feedback loops. |
Use Scenario: Powering safety-critical subsystems (e.g., emergency lighting, fire alarm sensors) where fault tolerance and immediate current limiting are mandatory. IC Role / Device Role / Timing Role: Delivers fast-cycle-by-cycle overcurrent protection (<100ns response) and automatic recovery after short-circuit removal. Use Value: Survives indefinite short-circuit conditions at full input voltage without latch-up or thermal runaway - validated per IEC 61000-4-5 surge immunity. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar high-current, constant-current/constant-voltage controller applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LTC3775EFE#PBF | Single-output synchronous buck controller with ±1.5% current accuracy, but no bidirectional current capability or CTRL2 thermal derating pin. | Designed for unidirectional high-current loads only; lacks sink capability required for regenerative or active load applications. | Select LTC3775EFE#PBF only when bidirectional operation is unnecessary and tighter current accuracy (±1.5%) is prioritized over thermal adaptability. |
| LM5119MT/NOPB | Two-phase synchronous buck controller with 6V–100V input, but no integrated current-sense amplifier or analog current programming interface. | Requires external current-sense amplifier and DAC for current regulation; not optimized for sub-1% current loop stability. | Choose LM5119MT/NOPB for ultra-wide input (up to 100V) and multiphase scalability, but expect added complexity and calibration effort for current control. |
Compared with LTC3775EFE#PBF and LM5119MT/NOPB, the LT3741EUF-1#PBF uniquely combines bidirectional current control, dual analog current programming, and integrated thermal derating - making it the only option among the three qualified for super-capacitor formation and active load testing.
Availability
LT3741EUF-1#PBF is available at Aetrix Electronics and suitable for industrial power supplies, super-capacitor charging systems, and high-reliability constant-current sources requiring stable component supply and long-term manufacturability.
Supply support for LT3741EUF-1#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 digital signal processing technologies, serving industrial, automotive, communications, and healthcare markets.
The LT3741EUF-1#PBF belongs to ADI's high-current DC/DC controller product line, designed specifically for applications demanding precise constant-current regulation, bidirectional power flow, and robust fault protection in harsh industrial environments.
FAQ
What is the key functional difference between LT3741EUF-1#PBF and LT3741EUF#PBF?
The LT3741EUF-1#PBF includes zero-crossing detection and modified control logic enabling true bidirectional current flow (source and sink), whereas the LT3741EUF#PBF is optimized for unidirectional operation only. This makes LT3741EUF-1#PBF suitable for regenerative loads and active load testing, while LT3741EUF#PBF is preferred for simpler constant-current sourcing applications like LED drivers.
Can LT3741EUF-1#PBF operate with input voltage below 6V?
No - the absolute minimum input voltage for LT3741EUF-1#PBF is 6V, as specified in the Absolute Maximum Ratings and Electrical Characteristics tables. Operation below 6V violates the device's operational specification and may result in unstable regulation or failure to start. For lower-input applications, consider alternative controllers such as the LT3957.
How does the CTRL2 pin function in LT3741EUF-1#PBF?
The CTRL2 pin in LT3741EUF-1#PBF accepts an analog voltage (0–1.5V) that dynamically scales down the regulated output current set by CTRL1. When used with an NTC thermistor divider, it enables automatic thermal derating - e.g., reducing current from 20A to 10A as temperature rises - without requiring microcontroller intervention or firmware updates.
What is the purpose of the exposed pad (Pin 21) on LT3741EUF-1#PBF?
The exposed pad (Pin 21) on LT3741EUF-1#PBF is electrically and thermally connected to GND. It must be soldered to a PCB copper pour to achieve the specified θJA of 37°C/W and ensure safe operation at full 20A load. Leaving it unconnected causes excessive junction temperature rise and potential thermal shutdown or permanent damage.
Does LT3741EUF-1#PBF support synchronization to an external clock?
Yes - LT3741EUF-1#PBF supports external clock synchronization via the SYNC pin. To ensure reliable locking, the internal oscillator (set by the RT resistor) must run at least 20% slower than the external SYNC frequency. The SYNC pin must be grounded when unused to prevent noise coupling and erratic switching behavior.
LT3741EUF-1#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-1#PBF FAQ
1.How can I place an order for LT3741EUF-1#PBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LT3741EUF-1#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-1#PBF reliable?
The price and inventory of LT3741EUF-1#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-1#PBF is usually 5 days.
3.What payment methods are accepted for LT3741EUF-1#PBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LT3741EUF-1#PBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LT3741EUF-1#PBF?
LT3741EUF-1#PBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LT3741EUF-1#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-1#PBF?
For technical support, including LT3741EUF-1#PBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LT3741EUF-1#PBF requirements.
6.How does Aetrix verify that LT3741EUF-1#PBF is sourced from the original manufacturer or authorized distributors?
All LT3741EUF-1#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-1#PBF meets industry standards.
7.What is the process for return or replacement of LT3741EUF-1#PBF?
All LT3741EUF-1#PBF units undergo pre-shipment inspection (PSI). If there is an issue with LT3741EUF-1#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-1#PBF part is unused and in its original packaging.
Return procedure for LT3741EUF-1#PBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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