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Analog Devices Inc. LT3741IFE#PBF
- Part No.:
- LT3741IFE#PBF
- Manufacturer:
- Analog Devices Inc.
- Category:
- DC DC Switching Controllers
- Package:
- 20-TSSOP (0.173", 4.40mm Width) Exposed Pad
- Datasheet:
-
LT3741IFE#PBF.pdf
- Description:
- IC REG CTRLR BUCK 20TSSOP
- Quantity:
- Payment:
- Shipping:
Inventory:107
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Product details
Overview
LT3741IFE#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). Used in supercapacitor charging and industrial current-source applications requiring extreme short-circuit protection.
For engineers reviewing the LT3741IFE#PBF datasheet, LT3741IFE#PBF pinout, LT3741IFE#PBF application, or LT3741IFE#PBF equivalent, key selection criteria include its dual CTRL-pin thermal/current limiting, 20-lead TSSOP package with exposed pad, 200kHz–1MHz programmable switching frequency, and ability to source/sink current - distinguishing it from the LT3741-1 variant.
Technical Context
The LT3741IFE#PBF implements average current-mode control using internal gm amplifiers (475 µA/V for current loop, 850 µA/V for voltage loop), with independent regulation paths for inductor current (via SENSE+/SENSE–) and output voltage (via FB). Its dual analog control inputs (CTRL1 and CTRL2) enable dynamic current limiting based on thermal feedback or external setpoint, with the lower voltage determining final regulated current.
It integrates high-side (HG) and low-side (LG) gate drivers with matched non-overlap timing (100 ns HG→LG, 60 ns LG→HG), 5V VCC_INT regulator, and 2V buffered reference (VREF) capable of 0.5 mA drive. The device supports synchronization via SYNC pin and programmable soft-start via SS pin with 11 µA charging current.
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 precise current sourcing/sinking for battery charging, LED drivers, and supercapacitor conditioning. |
| Voltage Regulation Accuracy | ±1.5% - maintains stable output voltage under load transients and line variations, critical for CV mode operation. |
| Switching Frequency Range | 200 kHz to 1 MHz - adjustable via RT resistor or external SYNC signal, enabling optimization of size vs. efficiency. |
| CTRL Pin Input Range | 0 V to 1.5 V - maps linearly to 0 mV–51 mV sense voltage across RS, enabling accurate analog current programming. |
| Shutdown Quiescent Current | <1 µA - enables ultra-low-power standby in always-on industrial or energy-harvesting systems. |
| Package Type | 20-Lead Plastic TSSOP with exposed thermal pad - provides robust thermal performance (θJA = 38°C/W) in compact footprint. |
Pinout & Package
LT3741IFE#PBF uses a 20-lead plastic TSSOP package with exposed thermal pad (Pin 21) soldered to PCB ground for thermal management. θJA = 38°C/W.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| VIN (Pin 3) | Main power input | Accepts 6V–36V supply; requires local 4.7µF low-ESR bypass capacitor to GND. |
| EN/UVLO (Pin 4) | Enable & undervoltage lockout | Turns on core at 1.55V; full shutdown below 0.5V; 130mV hysteresis; 5.5µA internal current source. |
| VREF (Pin 5) | Buffered reference output | 2.0V ±1% reference (1.94–2.06V) capable of 0.5mA drive for CTRL divider networks. |
| CTRL2 (Pin 6) | Thermal current limit input | Analog input (0–1.5V) that dynamically reduces regulated current when thermal stress is detected. |
| CTRL1 (Pin 8) | Primary current setpoint | Primary analog control input; sets high-level regulated current and overcurrent threshold (with +23mV offset). |
| SS (Pin 9) | Soft-start control | 11µA current source charges external capacitor to ramp regulated current gradually during startup. |
| FB (Pin 10) | Voltage feedback & OVP sense | 1.21V regulation threshold; triggers 13µs OVP shutdown if voltage exceeds 1.5V (~25% above regulation). |
| SENSE+ (Pin 11) | Current-sense inverting input | Connects to high-side of external sense resistor (RS); common-mode range extends to VIN – 2V. |
| SENSE– (Pin 12) | Current-sense non-inverting input | Reference current flows out to RS low-side; enables bidirectional current sensing capability. |
| VC (Pin 13) | Current-loop compensation | Connects to RC network (e.g., 20kΩ + 2nF) to stabilize average current-mode control loop. |
| RT (Pin 14) | Frequency setting | Resistor to GND sets fSW (200kHz–1MHz); internally current-limited to 60µA. |
| SYNC (Pin 15) | External clock sync input | Accepts TTL/CMOS clock; RT must be set 20% slower than SYNC frequency to avoid jitter. |
| HG (Pin 17) | High-side gate driver output | Drives external N-channel MOSFET gate; 2.3Ω pull-up / 1.3Ω pull-down impedance. |
| SW (Pin 18) | Switch node | Connects to source of high-side FET and drain of low-side FET; forms buck switching node. |
| CBOOT (Pin 19) | Floating high-side supply | 5V regulated boot supply for HG driver; requires Schottky diode from VCC_INT to CBOOT. |
| LG (Pin 20) | Low-side gate driver output | Drives external N-channel MOSFET gate; 2.3Ω pull-up / 1.0Ω pull-down impedance. |
| VCC_INT (Pin 1) | Internal 5V regulator output | Supplies gate drivers and internal circuits; current-limited to 50mA; tie to rail if VIN < 6V. |
| GND (Pins 2, 7, 16, 21) | Ground reference | Four dedicated GND pins plus exposed pad (Pin 21) - all must connect to solid PCB ground plane. |
Key Features
| Feature | Design Value |
|---|---|
| Dual analog current control (CTRL1 + CTRL2) | Enables real-time thermal derating: CTRL2 reduces regulated current before thermal shutdown occurs. |
| Average current-mode architecture | Provides inherent cycle-by-cycle current limiting and stable regulation across wide output voltage range (0V to VIN – 2V). |
| Bidirectional current capability | Supports both sourcing and sinking of inductor current - essential for supercapacitor charge/discharge and regenerative loads. |
| Integrated 5V VCC_INT regulator | Eliminates need for external bias supply; powers gate drivers and internal logic; includes UVLO and current limiting. |
| Programmable overvoltage protection | FB pin detects overvoltage >1.5V and disables switching for 13µs to safely discharge inductor energy. |
| Exposed thermal pad (TSSOP) | Enables efficient heat dissipation in high-current designs; exposed pad (Pin 21) must be soldered to PCB ground plane. |
Applications
| Supercapacitor Charging | Industrial Constant-Current Source |
|---|---|
|
Use Scenario: Rapidly charging large-value supercapacitors (e.g., 10–100F) from 0V to rated voltage while maintaining strict current limits and preventing thermal runaway. IC Role / Device Role / Timing Role: Primary current-regulating controller managing both charge phase (constant current) and termination phase (constant voltage), with cycle-by-cycle overcurrent protection. Use Value: Enables safe, repeatable supercap charging at up to 20A with ±6% current accuracy and automatic transition to CV mode at 1.21V FB threshold. |
Use Scenario: Providing stable, programmable DC current to electrochemical cells, resistive heaters, or test equipment loads in factory automation systems. IC Role / Device Role / Timing Role: High-accuracy current source controller with analog-setpoint interface (CTRL1/CTRL2) and thermal foldback to prevent overheating under sustained load. Use Value: Delivers precise 0–20A output with <1µA shutdown current and 200kHz–1MHz switching flexibility for EMI-sensitive environments. |
| LED Driver for High-Power Arrays | Extreme Short-Circuit Protected Power Supply |
|
Use Scenario: Driving multi-string, high-brightness LED arrays in architectural lighting or horticultural systems where dimming and thermal management are critical. IC Role / Device Role / Timing Role: Constant-current buck controller with dual analog control enabling PWM dimming via CTRL1 and thermal derating via CTRL2. Use Value: Maintains consistent LED brightness across temperature swings and prevents catastrophic failure during LED string open/short events. |
Use Scenario: Powering mission-critical subsystems (e.g., safety controllers, sensor interfaces) where output must survive indefinite short-circuit without damage or latch-up. IC Role / Device Role / Timing Role: Robust step-down controller with cycle-by-cycle current limiting, thermal shutdown (163°C), and <1µA shutdown state. Use Value: Guarantees reliable operation under fault conditions - no external current-limiting components required; survives continuous short-circuit indefinitely in shutdown mode. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar constant-current, constant-voltage buck controller applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LTC3775EFE#PBF | Single CTRL pin only; no CTRL2 thermal input; supports up to 15A; requires external VREF for precision current setting. | Lacks dual-analog current limiting; less suitable for thermally constrained supercap or LED applications requiring dynamic foldback. | Select when cost sensitivity outweighs need for thermal derating and 20A capability is not required. |
| LT3763EFE#PBF | Higher 80V input rating; optimized for LED drivers; includes PWM dimming interface; no SENSE– sink capability. | Designed for high-VF LED strings; lacks bidirectional current support and supercap-specific OVP timing. | Prefer for automotive or high-input-voltage LED applications; avoid for bidirectional or zero-VOUT supercap use cases. |
Compared with LT3741IFE#PBF, LTC3775EFE#PBF offers lower cost but sacrifices thermal foldback and peak current capability, while LT3763EFE#PBF delivers higher input voltage tolerance and LED-specific features at the expense of bidirectional operation and fine-grained analog current control.
Availability
LT3741IFE#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 and long-term manufacturability.
Supply support for LT3741IFE#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/constant-voltage regulation in demanding industrial and energy-storage applications - emphasizing thermal resilience, bidirectional capability, and analog programmability.
FAQ
What is the maximum output current supported by the LT3741IFE#PBF?
The LT3741IFE#PBF supports up to 20A regulated output current in continuous operation. This is achieved using average current-mode control with external sense resistor (RS) and precise analog voltage programming on the CTRL1 pin. Current accuracy is ±6% over temperature, and the device includes cycle-by-cycle overcurrent protection with a 23mV offset above the CTRL1-set threshold. Peak inductor current depends on input/output conditions and inductor selection.
Does the LT3741IFE#PBF support bidirectional current flow?
Yes, the LT3741IFE#PBF supports both sourcing and sinking of inductor current due to its unique topology and differential SENSE+ / SENSE– architecture. This enables true bidirectional operation - critical for supercapacitor charge/discharge cycles and regenerative braking interfaces. The LT3741-1 variant does not support sinking current, making the LT3741IFE#PBF the correct choice for applications requiring reverse current capability.
How does thermal derating work on the LT3741IFE#PBF?
Thermal derating on the LT3741IFE#PBF is implemented via the CTRL2 pin, which accepts an analog voltage (0–1.5V) to dynamically reduce the regulated output current before reaching thermal shutdown (163°C). When CTRL2 voltage falls below the CTRL1 voltage, the lower value determines the final current limit - allowing external NTC-based circuits or microcontroller feedback to preemptively scale back current under rising temperature conditions.
What is the purpose of the exposed pad on the LT3741IFE#PBF TSSOP package?
The exposed pad (Pin 21) on the LT3741IFE#PBF's 20-lead TSSOP package is electrically and thermally connected to GND. It must be soldered to a large PCB copper area to achieve the specified θJA of 38°C/W. This thermal path is essential for reliable operation at high output currents (e.g., 20A), preventing junction temperature exceedance and ensuring long-term reliability in industrial ambient conditions.
Can the LT3741IFE#PBF operate with 0V output voltage?
Yes, the LT3741IFE#PBF supports output voltages down to 0V (within its specified output voltage range of 0V to VIN – 2V), enabled by its average current-mode architecture and dedicated SENSE+/SENSE– differential sensing. This capability is essential for supercapacitor charging from fully discharged states and other zero-VOUT applications - unlike many buck controllers that require minimum output voltage headroom.
LT3741IFE#PBF Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- -
- Package/Case:
- 20-TSSOP (0.173", 4.40mm Width) 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-TSSOP-EP
LT3741IFE#PBF FAQ
1.How can I place an order for LT3741IFE#PBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LT3741IFE#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 LT3741IFE#PBF reliable?
The price and inventory of LT3741IFE#PBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LT3741IFE#PBF is usually 5 days.
3.What payment methods are accepted for LT3741IFE#PBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LT3741IFE#PBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LT3741IFE#PBF?
LT3741IFE#PBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LT3741IFE#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 LT3741IFE#PBF?
For technical support, including LT3741IFE#PBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LT3741IFE#PBF requirements.
6.How does Aetrix verify that LT3741IFE#PBF is sourced from the original manufacturer or authorized distributors?
All LT3741IFE#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 LT3741IFE#PBF meets industry standards.
7.What is the process for return or replacement of LT3741IFE#PBF?
All LT3741IFE#PBF units undergo pre-shipment inspection (PSI). If there is an issue with LT3741IFE#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 LT3741IFE#PBF part is unused and in its original packaging.
Return procedure for LT3741IFE#PBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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