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Analog Devices Inc. LT3741IUF#TRPBF
- Part No.:
- LT3741IUF#TRPBF
- Manufacturer:
- Analog Devices Inc.
- Category:
- DC DC Switching Controllers
- Package:
- 20-WFQFN Exposed Pad
- Datasheet:
-
LT3741IUF#TRPBF.pdf
- Description:
- IC REG CTRLR BUCK 20QFN
- Quantity:
- Payment:
- Shipping:
Inventory:2,815
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Product details
Overview
LT3741IUF#TRPBF 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 employs average current-mode control, supports sourcing and sinking current, and features ±6% current regulation accuracy, ±1.5% voltage regulation accuracy, and 6V–36V input range - used in supercapacitor charging and industrial current-source applications.
For engineers reviewing the LT3741IUF#TRPBF datasheet, LT3741IUF#TRPBF pinout, LT3741IUF#TRPBF application, or LT3741IUF#TRPBF equivalent, key selection criteria include its dual CTRL-pin thermal/current limiting, 20-lead 4mm × 4mm QFN package with exposed GND pad, programmable 200kHz–1MHz switching frequency, and ability to regulate down to 0V output while maintaining inductor current control across VIN – 2V output range.
Technical Context
The LT3741IUF#TRPBF implements average current-mode control using internal gm amplifiers (475 µA/V for current loop, 850 µA/V for voltage loop), with independent CTRL1/CTRL2 analog inputs setting regulated current level - the lower of the two voltages determines final output. Its unique topology enables bidirectional inductor current control (source/sink), distinguishing it from the LT3741-1 variant which lacks sinking capability.
It integrates a 2V buffered reference (VREF), 1.21V FB reference with overvoltage lockout at 1.5V, soft-start with 11 µA charging current, and precision EN/UVLO with 1.55V falling threshold and 130 mV hysteresis. The controller drives external high-side and low-side N-channel MOSFETs via HG/LG outputs with matched non-overlap timing (100 ns HG→LG, 60 ns LG→HG) and gate driver RDS(ON) values of 2.3 Ω / 1.3 Ω (HG pull-up/pull-down) and 2.3 Ω / 1.0 Ω (LG pull-up/pull-down).
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 6V to 36V - supports wide industrial input rails; absolute max 40V on VIN pin. |
| Output Current Regulation Accuracy | ±6% - ensures stable current delivery under varying load, temperature, and input conditions. |
| Voltage Regulation Accuracy | ±1.5% - maintains tight output voltage control when voltage loop engages (e.g., during CV mode). |
| Switching Frequency Range | 200 kHz to 1 MHz - set by RT resistor or synchronized via SYNC pin; enables EMI optimization and size/cost trade-offs. |
| CTRL Pin Input Range | 0 V to 1.5 V - maps linearly to 0 mV–51 mV sense voltage across RS, enabling precise analog current programming. |
| Shutdown Quiescent Current | <1 µA - minimizes system standby power loss; achieved at EN/UVLO < 0.5 V. |
| Package | 20-lead 4 mm × 4 mm plastic QFN with exposed GND pad - thermally enhanced for high-current operation (θJA = 37°C/W). |
Pinout & Package
LT3741IUF#TRPBF uses a thermally enhanced 20-lead (4 mm × 4 mm) plastic QFN package with exposed GND pad (Pin 21), requiring soldering to PCB for thermal and electrical integrity. Absolute maximum junction temperature is 125°C.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| EN/UVLO (Pin 1) | Enable and undervoltage lockout input | Activates internal bias at 1.55 V; full shutdown below 0.5 V; 130 mV hysteresis enables programmable UVLO with external resistor divider. |
| VREF (Pin 2) | Buffered 2 V reference output | Supplies up to 0.5 mA; used to generate CTRL1/CTRL2 bias voltages via resistor dividers. |
| CTRL2 (Pin 3) | Thermal current limit input | Analog input (0–1.5 V) that reduces regulated current when overheating occurs; lower voltage wins vs CTRL1. |
| GND (Pins 4, 11, 14, 21) | Ground reference and thermal path | Multiple ground connections plus exposed pad ensure low-impedance return and heat dissipation. |
| CTRL1 (Pin 5) | Main current regulation reference input | Sets high-level regulated current and overcurrent threshold; clamped to 1.5 V max; defines 51 mV full-scale sense voltage. |
| SS (Pin 6) | Soft-start control node | Charged at 11 µA; controls ramp rate of regulated current during startup to limit inrush. |
| FB (Pin 7) | Voltage feedback and overvoltage sense | 1.21 V reference; triggers 13 µs OVP shutdown if voltage exceeds 1.5 V (25% above regulation point). |
| SENSE+ (Pin 8) | Inverting input of current error amplifier | Connects to high-side of external sense resistor; common-mode range extends to VIN – 2 V. |
| SENSE– (Pin 9) | Non-inverting input of current error amplifier | Sinks reference current from CTRL1/CTRL2; forms differential sense pair with SENSE+. |
| VC (Pin 10) | Current-loop compensation node | Connects to RC network (e.g., 20 kΩ + 2 nF) to stabilize average current-mode control loop. |
| RT (Pin 12) | Frequency setting input | Resistor to GND sets fSW; current-limited to 60 µA; shorting to GND yields ~2 MHz (not recommended). |
| SYNC (Pin 13) | External clock synchronization input | Accepts TTL/CMOS clock; RT resistor must be set for 20% lower internal frequency to avoid jitter. |
| HG (Pin 15) | High-side gate driver output | Drives external high-side N-MOSFET gate; 2.3 Ω pull-up / 1.3 Ω pull-down impedance. |
| SW (Pin 16) | Switch node connection | Internal floating rail for HG driver; connects externally to source of high-side FET and drain of low-side FET. |
| CBOOT (Pin 17) | Floating bootstrap supply for HG driver | Charged via Schottky diode from VCC_INT; supplies ~5 V to HG driver during high-side conduction. |
| LG (Pin 18) | Low-side gate driver output | Drives external low-side N-MOSFET gate; 2.3 Ω pull-up / 1.0 Ω pull-down impedance. |
| VCC_INT (Pin 19) | Internally regulated 5 V supply | Powers internal circuitry and charges CBOOT; current-limited to 50 mA; disable at VIN < 6 V by tying to rail. |
| VIN (Pin 20) | Main input power supply | Requires local 4.7 µF low-ESR bypass capacitor; absolute max 40 V. |
Key Features
| Feature | Design Value |
|---|---|
| Bidirectional current control (source/sink) | Enables active discharge and regenerative operation in supercapacitor charging and battery simulation systems. |
| Dual analog current control inputs (CTRL1/CTRL2) | Allows simultaneous regulation (e.g., current setpoint + thermal derating) without external logic or microcontroller intervention. |
| Accurate 1.21 V FB reference with 1.5 V OVP threshold | Provides precise CV regulation and fast overvoltage protection (13 µs shutdown) to safeguard downstream loads. |
| Programmable soft-start via SS pin (11 µA current source) | Eliminates need for external timer circuits; enables controlled current ramp to prevent inrush into capacitive loads. |
| Integrated 2 V VREF with 0.5 mA drive capability | Simplifies generation of stable CTRL1/CTRL2 bias voltages using standard resistor dividers - no external reference required. |
| Thermal shutdown with 163°C trip and 8°C hysteresis | Protects against sustained overload or poor heatsinking; forces reset and pulls SS low to halt current ramp. |
Applications
| Supercapacitor Charging | Industrial Constant-Current Source |
|---|---|
|
Use Scenario: Rapidly charge large-value supercapacitors (e.g., 100 F) from 0 V to rated voltage while limiting inrush and ensuring balanced cell voltage. IC Role / Device Role / Timing Role: Primary current-regulating controller managing bidirectional energy flow; regulates average inductor current with ±6% accuracy regardless of output voltage. Use Value: Enables safe, efficient, and repeatable supercap charging cycles without external current-sense amplifiers or discrete protection circuitry. |
Use Scenario: Provide stable 0–20 A current output for electroplating, LED testing, or sensor calibration where voltage may vary widely (e.g., 0–30 V). IC Role / Device Role / Timing Role: High-accuracy current-mode controller operating in CC mode until voltage limit is reached; switches seamlessly to CV mode. Use Value: Delivers consistent current across full output voltage range (0 V to VIN – 2 V), eliminating need for separate CC/CV controllers. |
| High-Reliability Short-Circuit Protection | Laser Diode Driver (CV+CC) |
|
Use Scenario: Power mission-critical industrial equipment requiring immediate shutdown upon short-circuit detection with minimal fault energy. IC Role / Device Role / Timing Role: Cycle-by-cycle overcurrent protector using dedicated SENSE+/SENSE– interface; triggers within one switching cycle at 23 mV over setpoint. Use Value: Limits fault current to defined maximum (e.g., 20 A) with sub-microsecond response - far faster than thermal or microcontroller-based protection. |
Use Scenario: Drive high-power laser diodes requiring strict current regulation and overvoltage clamp to prevent catastrophic optical damage. IC Role / Device Role / Timing Role: Dual-loop controller enforcing both current limit (via CTRL1) and voltage ceiling (via FB divider); OVP shuts down switching in 13 µs. Use Value: Guarantees laser diode safety by preventing both overcurrent and overvoltage events - critical for Class 4 laser systems. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar constant-current, constant-voltage step-down controller applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LTC3776EFE#TRPBF | Single-phase, 2-phase capable controller; supports up to 60 A with external MOSFETs; requires external current-sense amplifier for precision CC. | Targeted at higher-current multi-phase designs; lacks integrated bidirectional current control and dual CTRL inputs. | Choose LTC3776 for >20 A or multi-phase scalability; avoid if bidirectional current or analog thermal derating is required. |
| LT3741IUF-1#TRPBF | Same pinout and package; omits sinking capability and zero-cross comparator; simplified for parallel operation or unidirectional use only. | Used where only sourcing is needed (e.g., LED drivers); cannot actively discharge or support regenerative loads. | Choose LT3741IUF-1#TRPBF to reduce cost and complexity when sink functionality is unnecessary. |
Compared with LTC3776EFE#TRPBF and LT3741IUF-1#TRPBF, the LT3741IUF#TRPBF uniquely delivers integrated bidirectional current control, dual analog current inputs for thermal derating, and cycle-by-cycle overcurrent protection - making it optimal for supercapacitor charging and high-integrity CC/CV systems where sinking and fast fault response are mandatory.
Availability
LT3741IUF#TRPBF 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 and long-term manufacturability.
Supply support for LT3741IUF#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 (ADI) acquired Linear Technology in 2017 and continues to develop and support its high-performance power management portfolio, including precision DC/DC controllers and regulators.
The LT3741IUF#TRPBF belongs to ADI's high-accuracy current-mode controller product line, engineered specifically for applications demanding simultaneous constant-current and constant-voltage regulation with robust fault protection and thermal management - such as energy storage, test equipment, and industrial automation.
FAQ
What is the primary function of the LT3741IUF#TRPBF in a power system?
The LT3741IUF#TRPBF functions as a synchronous step-down DC/DC controller optimized for precise constant-current (CC) and constant-voltage (CV) regulation. It directly controls external high-side and low-side N-channel MOSFETs to maintain output current up to 20 A with ±6% accuracy and output voltage with ±1.5% accuracy - making it ideal for supercapacitor charging and industrial current-source applications where both CC and CV modes must coexist.
How does the LT3741IUF#TRPBF achieve bidirectional current control?
The LT3741IUF#TRPBF achieves bidirectional current control through its unique average current-mode architecture and dedicated SENSE+/SENSE– differential inputs, allowing it to regulate inductor current regardless of polarity. Unlike unidirectional controllers, it can actively sink current - enabling rapid supercapacitor discharge, regenerative braking simulation, and active load testing. This capability is intrinsic to the LT3741 (not LT3741-1) and requires no external circuitry.
Can the LT3741IUF#TRPBF operate with 0 V output voltage?
Yes, the LT3741IUF#TRPBF supports output voltages down to 0 V while maintaining accurate inductor current regulation across its full 0 V to (VIN – 2 V) range. This is enabled by its average current-mode control architecture and wide common-mode input range at the SENSE pins (0 V to VIN – 2 V). It remains in CC mode until the FB voltage reaches 1.21 V, then transitions smoothly to CV mode - supporting true zero-volt start-up and operation.
What is the role of the CTRL2 pin on the LT3741IUF#TRPBF?
The CTRL2 pin on the LT3741IUF#TRPBF provides an independent analog input (0–1.5 V) for thermal derating or secondary current limiting. Its voltage is compared with CTRL1, and the lower value determines the final regulated current. For example, connecting a thermistor-based voltage divider to CTRL2 allows automatic current reduction as temperature rises - a hardware-based safety feature that operates independently of microcontrollers or software.
Does the LT3741IUF#TRPBF require external components for soft-start?
No, the LT3741IUF#TRPBF implements soft-start internally via the SS pin, which is charged by a precise 11 µA current source. An external capacitor to ground sets the ramp time - for example, a 100 nF capacitor yields ~9 ms ramp (1.1 V / 11 µA). This eliminates the need for external timers or DACs, simplifying design while ensuring repeatable, controlled current rise during startup to prevent inrush into capacitive or low-impedance loads.
LT3741IUF#TRPBF Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- -
- Package/Case:
- 20-WFQFN Exposed Pad
- Packaging:
- Tape & Reel (TR)
- 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)
LT3741IUF#TRPBF FAQ
1.How can I place an order for LT3741IUF#TRPBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LT3741IUF#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 LT3741IUF#TRPBF reliable?
The price and inventory of LT3741IUF#TRPBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LT3741IUF#TRPBF is usually 5 days.
3.What payment methods are accepted for LT3741IUF#TRPBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LT3741IUF#TRPBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LT3741IUF#TRPBF?
LT3741IUF#TRPBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LT3741IUF#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 LT3741IUF#TRPBF?
For technical support, including LT3741IUF#TRPBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LT3741IUF#TRPBF requirements.
6.How does Aetrix verify that LT3741IUF#TRPBF is sourced from the original manufacturer or authorized distributors?
All LT3741IUF#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 LT3741IUF#TRPBF meets industry standards.
7.What is the process for return or replacement of LT3741IUF#TRPBF?
All LT3741IUF#TRPBF units undergo pre-shipment inspection (PSI). If there is an issue with LT3741IUF#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 LT3741IUF#TRPBF part is unused and in its original packaging.
Return procedure for LT3741IUF#TRPBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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