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Analog Devices Inc. LT3641EUFD#TRPBF
- Part No.:
- LT3641EUFD#TRPBF
- Manufacturer:
- Analog Devices Inc.
- Package:
- 28-WFQFN Exposed Pad
- Datasheet:
-
LT3641EUFD#TRPBF.pdf
- Description:
- IC REG BCK ADJ 1.3A/1.DL 28QFN
- Quantity:
- Payment:
- Shipping:
Inventory:4,284
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Product details
Overview
LT3641EUFD#TRPBF from Analog Devices (formerly Linear Technology) is a dual-channel monolithic buck regulator IC with integrated power-on reset and window-mode watchdog timer. It delivers 5V/0.8A from 7–42V input (HV channel) and 3.3V/0.5A from 2.5–5.5V input (LV channel), operating synchronously at 2MHz with Burst Mode® for light-load efficiency. It serves as primary DC/DC power management in automotive ECU and industrial control systems requiring robust transient protection and system-level fault monitoring.
For engineers reviewing the LT3641EUFD#TRPBF datasheet, LT3641EUFD#TRPBF pinout, LT3641EUFD#TRPBF application, or LT3641EUFD#TRPBF equivalent, key selection criteria include its dual-input voltage ranges (4–42V HV + 2.5–5.5V LV), programmable 350kHz–2.5MHz switching frequency via RT resistor, adjustable POR/watchdog timing via external capacitors, and thermal-enhanced 28-pin 4mm × 5mm QFN package with exposed GND pad.
Technical Context
The LT3641EUFD#TRPBF integrates two independent current-mode buck regulators sharing a single adjustable oscillator: a nonsynchronous HV channel (2.4A internal NPN switch, 4–42V input, 55V transient tolerance) and a synchronous LV channel (1.1A internal PMOS/NMOS pair, 2.5–5.5V input). Both channels feature cycle-by-cycle current limiting, soft-start via SS1/SS2 pins, and output regulation referenced to 1.265V (FB1) and 600mV (FB2).
Its power-on reset (RST1/RST2) and window-mode watchdog (WDO/WDI/CWDT) operate independently of regulation status-RST1 triggers after FB1 exceeds 1.165V, RST2 after FB2 exceeds 550mV, and WDO asserts if WDI pulses fall outside user-defined upper/lower boundaries set by CWDT capacitance. All timing functions are capacitor-programmable with no external logic required.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| HV Input Range | 4V to 42V continuous; withstands 55V nonrepetitive transients - enables direct battery connection in 12V/24V automotive systems without external clamping. |
| LV Input Range | 2.5V to 5.5V - supports post-regulation from HV output or independent low-voltage rails like USB or LDOs. |
| Switching Frequency | 350kHz to 2.5MHz, set by RT resistor - allows optimization between small magnetics (high-freq) and high efficiency (low-freq). |
| Quiescent Current | 290μA typical - maintains ultra-low standby power in always-on automotive modules. |
| Watchdog Window | Programmable lower/upper boundaries (e.g., 2.0ms/32ms with 820pF CWDT) - detects both stuck and runaway microprocessor behavior. |
| Power-On Reset Delay | 8–11ms (tRST) with 220pF CPOR - ensures stable rail sequencing before MCU release. |
| Thermal Package | 28-pin 4mm × 5mm QFN with exposed GND pad (θJC = 3.4°C/W) - enables >3W dissipation in compact layouts without heatsinks. |
Pinout & Package
LT3641EUFD#TRPBF uses a thermally enhanced 28-pin plastic QFN package (4mm × 5mm) with exposed GND pad (Pin 29), rated for –40°C to +125°C junction temperature. The exposed pad must be soldered to PCB ground for optimal thermal performance (θJA = 43°C/W).
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| FB1 (Pin 6) | High-voltage feedback reference input | Regulated to 1.265V; sets VOUT1 via resistor divider - determines accuracy and stability of primary 5V rail. |
| FB2 (Pin 1) | Low-voltage feedback reference input | Regulated to 600mV; sets VOUT2 via resistor divider - enables precise 3.3V or lower outputs with minimal component count. |
| RT (Pin 7) | Oscillator frequency programming node | Resistor-to-ground sets switching frequency (350kHz–2.5MHz); enables layout-driven trade-off between size and efficiency. |
| CPOR (Pin 12) | Reset and watchdog timeout capacitor node | Single capacitor programs both power-on reset delay (RST1/RST2) and WDO assertion period - simplifies BOM and layout. |
| CWDT (Pin 11) | Watchdog window boundary capacitor node | Capacitor sets upper/lower timing windows for WDI pulse detection - implements fail-safe μP supervision without external timers. |
| EN/UVLO (Pin 3) | Global enable and VIN undervoltage lockout | 1.26V threshold with 2μA hysteresis - provides accurate, programmable startup voltage for battery-powered systems. |
| EN2 (Pin 27) | LV channel enable input | Threshold at 100mV below FB2 target (≈500mV); 50mV hysteresis - enables independent sequencing of secondary rail. |
| PGOOD2 (Pin 2) | LV output power-good indicator | Open-drain output active when FB2 ≥ 550mV ±40mV hysteresis - signals valid 3.3V rail to MCU or FPGA. |
| WDE (Pin 13) | Watchdog enable control | Active-low enable for watchdog function - allows runtime disable during firmware updates or debug modes. |
| WDI (Pin 14) | Watchdog input pulse receiver | Accepts μP-generated pulses; monitors inter-pulse timing against CWDT-defined windows - detects software hangs or clock faults. |
| RST1/RST2 (Pins 9/8) | Open-drain reset outputs | Asserted until respective FB pin reaches threshold, then held for CPOR-defined timeout - provides clean, sequenced MCU reset. |
| SW1 (Pin 19) | HV switch node | Connects to HV inductor and catch diode cathode - carries full HV switching current; requires careful layout for EMI and thermal management. |
| SW2 (Pin 25) | LV switch node | Connects to LV inductor - synchronous topology eliminates external Schottky, reducing losses and footprint. |
| BST (Pin 21) | HV bootstrap supply | Drives HV NPN base via external diode/capacitor - enables efficient saturation of internal switch above 4V input. |
| VIN / VIN2 (Pins 22/24) | Independent input supplies | VIN powers HV channel and bias circuitry; VIN2 powers LV channel and internal regulators - enables flexible two-stage or split-rail architectures. |
| GND (Pins 15,16,23,26,29) | Ground terminals | Multiple dedicated GND pins + exposed pad - minimizes ground impedance and improves noise immunity in noisy automotive environments. |
Key Features
| Feature | Design Value |
|---|---|
| Integrated window-mode watchdog timer | Monitors μP pulse timing against programmable upper/lower boundaries - prevents false resets from jitter while catching missed pulses or infinite loops. |
| Dual independent soft-start controls (SS1/SS2) | Capacitor-programmed ramp rates for each output - enables precise power sequencing and inrush current limiting across multiple rails. |
| Nonsynchronous HV + synchronous LV architecture | HV channel uses internal NPN + external diode; LV channel uses integrated PMOS/NMOS - balances cost, efficiency, and integration for multi-rail systems. |
| Input transient protection to 55V | Withstands load-dump events per ISO 7637-2 without external TVS - reduces bill-of-materials in automotive applications. |
| 290μA quiescent current in Burst Mode® | Maintains regulation at light loads while minimizing standby power - extends battery life in always-on telematics modules. |
| Exposed-pad QFN thermal design | θJC = 3.4°C/W enables >3W continuous dissipation - supports high-current operation in space-constrained enclosures. |
Applications
| Automotive Engine Control Unit (ECU) | Industrial Programmable Logic Controller (PLC) |
|---|---|
Use Scenario: Powers MCU, CAN transceiver, and sensor interface circuits from 12V/24V vehicle battery with load-dump immunity. IC Role / Device Role / Timing Role: Dual-buck regulator providing isolated 5V (MCU core) and 3.3V (peripherals) rails; POR ensures deterministic boot; watchdog supervises firmware execution. Use Value: Eliminates need for discrete reset IC and external TVS, reducing board area by >30% versus discrete solutions while meeting AEC-Q100 Grade 1 requirements. | Use Scenario: Supplies field I/O modules and real-time controller in factory automation systems with wide input voltage variation. IC Role / Device Role / Timing Role: Primary DC/DC converter delivering stable 5V/0.8A and 3.3V/0.5A from unregulated 9–36V DC bus; programmable UVLO adapts to varying supply conditions. Use Value: Adjustable switching frequency allows use of smaller inductors (e.g., 2.2μH at 2MHz), cutting solution size by 40% vs 500kHz designs without sacrificing efficiency. |
| Medical Diagnostic Imaging Interface | Ruggedized IoT Edge Gateway |
Use Scenario: Powers FPGA, ADC, and communication interfaces in portable ultrasound or X-ray control units with strict EMI and reliability requirements. IC Role / Device Role / Timing Role: Dual-output regulator with Burst Mode® for low-noise standby; PGOOD2 signals rail readiness to FPGA configuration logic. Use Value: 290μA IQ and <1μA shutdown current extend battery runtime in handheld devices; QFN package supports conformal coating for moisture resistance. | Use Scenario: Provides power to cellular modem, secure MCU, and environmental sensors in outdoor wireless gateways exposed to temperature extremes. IC Role / Device Role / Timing Role: High-reliability buck regulator operating from solar-charged LiFePO₄ battery (max 36V); watchdog guards against modem firmware crashes. Use Value: 125°C-rated QFN package and -40°C to +125°C operation ensure uninterrupted service in desert or arctic deployments without derating. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar dual-buck regulator applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LT3645EUFD#TRPBF | Same pinout, higher HV current (2.8A vs 2.4A), extended LV input (up to 6V), added spread-spectrum modulation | Supports higher-power 5V rails and noise-sensitive RF sections; requires updated inductor rating | Select when >0.8A HV output or EMI reduction is critical; otherwise LT3641EUFD#TRPBF offers cost advantage. |
| TPS65270RGET | TI dual-buck (3A/2A), fixed 5V/3.3V outputs, no integrated watchdog/POR, 4.5–18V input only | Lacks system supervision features; requires external reset IC and TVS for automotive use | Choose for cost-sensitive industrial applications where watchdog and transient protection are handled externally. |
Compared with LT3645EUFD#TRPBF and TPS65270RGET, the LT3641EUFD#TRPBF uniquely combines automotive-grade transient tolerance, integrated window watchdog, and capacitor-programmable POR in a single 4mm × 5mm QFN-enabling complete power + supervision functionality without supplemental ICs.
Availability
LT3641EUFD#TRPBF is available at Aetrix Electronics and suitable for automotive electronic control units, industrial PLCs, and medical diagnostic interfaces requiring stable component supply, long-term lifecycle support, and AEC-Q100-aligned reliability.
Supply support for LT3641EUFD#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 acquired Linear Technology in 2017 and maintains its precision analog and power management portfolio. Linear's legacy engineering rigor ensures high-reliability, specification-guaranteed performance across temperature and lifetime.
The LT3641EUFD#TRPBF belongs to Linear's monolithic DC/DC regulator family designed for automotive and industrial systems demanding integrated power conversion, sequencing, and fault supervision in minimal footprint.
FAQ
What input voltage ranges does the LT3641EUFD#TRPBF support for each channel?
The LT3641EUFD#TRPBF supports 4V to 42V continuous input on the high-voltage channel (VIN pin), with transient tolerance up to 55V for one second. The low-voltage channel (VIN2 pin) operates from 2.5V to 5.5V. These ranges allow direct connection to automotive batteries and post-regulated rails. The LT3641EUFD#TRPBF's EN/UVLO pin enables programmable undervoltage lockout for customized startup thresholds.
How is the switching frequency programmed on the LT3641EUFD#TRPBF?
The LT3641EUFD#TRPBF uses an external resistor from the RT pin to ground to set switching frequency between 350kHz and 2.5MHz. For example, a 32.4kΩ resistor yields 2MHz operation. The IC also accepts external synchronization via the SYNC pin (350kHz–2.5MHz), but requires the internal oscillator frequency to be at least 20% lower than the SYNC signal. The LT3641EUFD#TRPBF's datasheet provides a full RT vs. frequency table for precise selection.
Does the LT3641EUFD#TRPBF include built-in protection features?
Yes, the LT3641EUFD#TRPBF integrates multiple protection mechanisms: cycle-by-cycle current limiting on both channels, thermal shutdown, input overvoltage transient protection (55V), and short-circuit robustness. Its HV channel includes valley current limiting via the DA pin to prevent inductor saturation during overload. The LT3641EUFD#TRPBF also features programmable soft-start (SS1/SS2) and undervoltage lockout (EN/UVLO) to prevent erratic startup behavior.
Can the LT3641EUFD#TRPBF's power-on reset and watchdog functions be disabled?
The LT3641EUFD#TRPBF's power-on reset (RST1/RST2) cannot be fully disabled but can be shortened by reducing CPOR capacitance; however, removing CPOR entirely disables reset assertion. The watchdog function is enabled only when WDE is pulled low - holding WDE high disables watchdog monitoring while preserving POR functionality. The LT3641EUFD#TRPBF's WDE pin thus provides runtime control over supervision without affecting power sequencing.
What package type and thermal characteristics does the LT3641EUFD#TRPBF use?
The LT3641EUFD#TRPBF uses a 28-pin 4mm × 5mm plastic QFN package (UFD) with exposed GND pad (Pin 29). Its thermal resistance is θJC = 3.4°C/W and θJA = 43°C/W when properly mounted on a 4-layer PCB with 1-in² copper pour under the pad. This enables >3W continuous power dissipation without external heatsinking. The LT3641EUFD#TRPBF's package is RoHS-compliant and rated for –40°C to +125°C operation.
LT3641EUFD#TRPBF Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- -
- Package/Case:
- 28-WFQFN Exposed Pad
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Active
- Function:
- Step-Down
- Output Configuration:
- Positive
- Topology:
- Buck
- Output Type:
- Adjustable
- Number of Outputs:
- 2
- Voltage - Input (Min):
- 2.5V
- Voltage - Input (Max):
- 42V
- Voltage - Output (Min/Fixed):
- 0.6V, 1.265V
- Voltage - Output (Max):
- 39.48V
- Current - Output:
- 1.3A, 1.1A
- Frequency - Switching:
- 500kHz ~ 2MHz
- Synchronous Rectifier:
- Both
- Operating Temperature:
- -40°C ~ 125°C (TJ)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 28-QFN (4x5)
LT3641EUFD#TRPBF FAQ
1.How can I place an order for LT3641EUFD#TRPBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LT3641EUFD#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 LT3641EUFD#TRPBF reliable?
The price and inventory of LT3641EUFD#TRPBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LT3641EUFD#TRPBF is usually 5 days.
3.What payment methods are accepted for LT3641EUFD#TRPBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LT3641EUFD#TRPBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LT3641EUFD#TRPBF?
LT3641EUFD#TRPBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LT3641EUFD#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 LT3641EUFD#TRPBF?
For technical support, including LT3641EUFD#TRPBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LT3641EUFD#TRPBF requirements.
6.How does Aetrix verify that LT3641EUFD#TRPBF is sourced from the original manufacturer or authorized distributors?
All LT3641EUFD#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 LT3641EUFD#TRPBF meets industry standards.
7.What is the process for return or replacement of LT3641EUFD#TRPBF?
All LT3641EUFD#TRPBF units undergo pre-shipment inspection (PSI). If there is an issue with LT3641EUFD#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 LT3641EUFD#TRPBF part is unused and in its original packaging.
Return procedure for LT3641EUFD#TRPBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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