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Analog Devices Inc. LT3641IFE#TRPBF
- Part No.:
- LT3641IFE#TRPBF
- Manufacturer:
- Analog Devices Inc.
- Package:
- 28-TSSOP (0.173", 4.40mm Width) Exposed Pad
- Datasheet:
-
LT3641IFE#TRPBF.pdf
- Description:
- IC REG BUCK ADJ DL 28TSSOP
- Quantity:
- Payment:
- Shipping:
Inventory:2,702
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Product details
Overview
LT3641IFE#TRPBF from Analog Devices (formerly Linear Technology) is a dual-channel monolithic buck switching regulator IC with integrated power-on reset and window-mode watchdog timer. It delivers 5V/0.8A from 4–42V input (HV channel) and 3.3V/0.5A from 2.5–5.5V input (LV channel), operating synchronously at 350kHz–2.5MHz. Used in automotive ECU power rails where transient robustness and microcontroller supervision are critical.
For engineers reviewing the LT3641IFE#TRPBF datasheet, LT3641IFE#TRPBF pinout, LT3641IFE#TRPBF application, or LT3641IFE#TRPBF equivalent, key selection factors include its dual-input voltage ranges, programmable reset/watchdog timing via external capacitors, Burst Mode® operation for light-load efficiency, and thermal performance in the 28-pin TSSOP package with exposed pad.
Technical Context
The LT3641IFE#TRPBF integrates two independent current-mode buck regulators sharing a single adjustable oscillator. The high-voltage channel uses a nonsynchronous NPN switch with 2.4A peak current capability and 55V transient protection; the low-voltage channel employs synchronous MOSFETs with 1.1A combined PMOS/NMOS current limit and 200–275mΩ RDS(ON).
Its power-on reset asserts until FB1 exceeds 1.165V and FB2 exceeds 550mV, with timeout set by CPOR capacitor. The window-mode watchdog monitors WDI pulse edges-asserting WDO if intervals fall outside tWDL = 1.68–2.2ms or tWDU = 27–35ms (CWDT = 820pF)-enabling fail-safe μP supervision in safety-critical systems.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| HV Input Range | 4V to 42V continuous, with 55V/1s transient tolerance - enables direct battery connection in 12V/24V automotive systems. |
| LV Input Range | 2.5V to 5.5V - supports post-regulation from HV output or independent 3.3V/5V sources. |
| Switching Frequency | Adjustable 350kHz to 2.5MHz via RT resistor - allows optimization of inductor size vs. efficiency (e.g., 2MHz used in compact 5V/0.8A + 3.3V/0.5A design). |
| Quiescent Current | 290μA typical - sustains low-power standby in always-on automotive modules. |
| FB1 Reference | 1.265V ±25mV - sets precise 5V output with standard 1% resistor divider (e.g., 100k/24.3k). |
| FB2 Reference | 600mV ±15mV - enables accurate 3.3V output using 1% resistors (e.g., 50k/45.5k). |
| Shutdown Current | <1μA - minimizes battery drain during system sleep modes. |
Pinout & Package
The LT3641IFE#TRPBF is housed in a thermally enhanced 28-lead plastic TSSOP package (FE) with exposed pad (Pin 29) soldered to PCB ground for θJA = 30°C/W. Pin numbering follows standard top-view layout with GND on Pins 15, 16, 23, 26, and exposed pad 29.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| FB1 (Pin 6) | High-voltage feedback input | Regulates to 1.265V; connects to resistor divider tap for output voltage setting (e.g., 5V). |
| FB2 (Pin 1) | Low-voltage feedback input | Regulates to 600mV; sets LV output (e.g., 3.3V) with precision tracking capability. |
| EN/UVLO (Pin 3) | Enable and undervoltage lockout input | 1.26V threshold enables programmable VIN start-up; 2μA hysteresis prevents noise-induced shutdown. |
| CPOR (Pin 12) | Reset and watchdog timer capacitor | Single capacitor sets both RST1/RST2 timeout and WDO assertion period (e.g., 220pF → 9.5ms). |
| CWDT (Pin 11) | Watchdog timing capacitor | Defines window boundaries: tWDL and tWDU scale linearly with capacitance (e.g., 820pF → 2–35ms range). |
| WDI (Pin 14) | Watchdog input | Accepts μP pulses; falling edges must fall within programmable window to prevent WDO assertion. |
| RST1/RST2 (Pins 9/8) | Open-drain reset outputs | Pulled low until respective FB pin reaches threshold; drive microcontroller reset pins directly. |
| WDO (Pin 10) | Watchdog output | Open-drain flag asserted when WDI violates window timing; initiates system reset sequence. |
Key Features
| Feature | Design Value |
|---|---|
| Burst Mode® operation | Maintains high efficiency (>85%) at light loads (e.g., 10mA) while limiting output ripple to <20mVPP. |
| Programmable soft-start | Independent SS1/SS2 pins allow controlled ramp-up of HV and LV outputs to prevent inrush current and enable sequencing. |
| Input transient protection | Withstands 55V/1s transients on VIN - eliminates need for external TVS in 24V automotive applications. |
| Synchronous LV channel | Integrated PMOS/NMOS switches eliminate external Schottky diode, reducing BOM count and improving efficiency at 3.3V/0.5A. |
| Thermal enhancement | Exposed pad (Pin 29) tied to PCB ground achieves θJC = 8°C/W - supports 1.3A HV + 1.1A LV continuous operation at 85°C ambient. |
Applications
| Automotive Engine Control Unit (ECU) | Industrial PLC I/O Module |
|---|---|
Use Scenario: Powering MCU, CAN transceiver, and sensor interface circuitry from 12V battery with cold-crank resilience. IC Role / Device Role / Timing Role: Dual-buck regulator providing isolated 5V (MCU core) and 3.3V (peripherals); RST1/RST2 coordinate power-up sequencing; WDO supervises firmware execution. Use Value: 55V transient tolerance avoids external clamping; programmable reset ensures deterministic boot after battery recovery; window watchdog detects stuck/frozen μP states. | Use Scenario: Generating 5V logic rail and 3.3V analog supply in DIN-rail mounted controller with wide input range. IC Role / Device Role / Timing Role: Primary DC-DC converter with integrated POR and watchdog; CPOR/CWDT capacitors configure system-level reset timing and fault response. Use Value: Single-chip solution reduces board area vs. discrete regulators + supervisor IC; Burst Mode® extends hold-up time during brownouts. |
| Medical Diagnostic Imaging Subsystem | Telecom Remote Radio Unit (RRU) |
Use Scenario: Supplying FPGA, ADC, and clock generator in portable ultrasound device requiring low-noise, sequenced power rails. IC Role / Device Role / Timing Role: HV channel powers 5V FPGA core; LV channel supplies 3.3V ADC reference; SS1/SS2 enable voltage tracking during startup. Use Value: 290μA quiescent current extends battery life; 40mV PGOOD2 hysteresis ensures stable enable signaling to downstream logic. | Use Scenario: Power conversion in outdoor base station unit exposed to 48V telecom supply with lightning surge risk. IC Role / Device Role / Timing Role: HV buck accepts 36–57V input; LV buck generates 3.3V for control logic; WDE/WDO provide fail-safe restart on processor hang. Use Value: 55V transient rating meets ITU-T K.20 surge immunity; window watchdog prevents false resets from periodic noise bursts. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar dual-output buck regulator with supervision applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LTC3642EFE#TRPBF | Same pinout, identical feature set, but rated for –40°C to 125°C (E-grade) instead of I-grade; FB1 = 1.25V (vs. 1.265V), slightly lower accuracy. | Valid for commercial/industrial environments without extended temperature validation; not qualified for automotive underhood use. | Select when cost sensitivity outweighs need for I-grade temp assurance and tighter FB1 tolerance. |
| TPS65270RGET | 3.5V–28V HV input, 1.2A/1.5A outputs, no integrated watchdog/POR; requires external supervisor IC for reset timing. | Higher HV current capability but lacks autonomous supervision - increases BOM and layout complexity for safety-critical designs. | Choose only if higher output current is mandatory and external supervision is acceptable. |
Compared with LTC3642EFE#TRPBF and TPS65270RGET, the LT3641IFE#TRPBF provides guaranteed –40°C to 125°C operation, tighter FB1 reference (±25mV), and fully integrated window watchdog - making it optimal for automotive and industrial systems requiring self-contained power sequencing and fault detection without external components.
Availability
LT3641IFE#TRPBF is available at Aetrix Electronics and suitable for automotive electronic control units, industrial PLCs, and medical imaging subsystems requiring stable component supply across extended temperature ranges and transient-prone environments.
Supply support for LT3641IFE#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 full support for legacy Linear power products. The company specializes in high-performance analog, mixed-signal, and power management ICs for demanding applications.
The LT3641IFE#TRPBF belongs to Linear's monolithic DC/DC regulator family designed for automotive, industrial, and medical systems requiring robust dual-rail power conversion with integrated system supervision functions.
FAQ
What is the maximum input voltage the LT3641IFE#TRPBF can withstand without damage?
The LT3641IFE#TRPBF has an absolute maximum VIN rating of 55V for nonrepetitive 1-second transients, and 42V for continuous operation. This allows direct connection to 24V automotive batteries during load-dump events. Exceeding 55V even briefly may cause permanent damage, and operation above 42V continuously requires careful thermal management due to reduced efficiency and increased power dissipation in the HV channel.
How do I configure the power-on reset timeout for the LT3641IFE#TRPBF?
The power-on reset timeout for both RST1 and RST2 is set by the capacitor on CPOR (Pin 12). With CPOR = 220pF, the typical timeout is 9.5ms across –40°C to 125°C. The relationship is linear: doubling CPOR doubles the timeout. Ensure the capacitor is ceramic with X7R dielectric and placed close to CPOR and ground to minimize noise coupling that could affect reset reliability.
Can the LT3641IFE#TRPBF operate with only the low-voltage input (VIN2) powered?
No - the LT3641IFE#TRPBF requires VIN (Pin 22) to be ≥3.6V to power internal bias circuitry, even if only the LV channel is active. VIN2 (Pin 24) alone cannot sustain operation because the internal regulator draws primary current from VIN2 only when VIN2 > 3V, but auxiliary power for logic, oscillators, and references comes from VIN. If VIN is absent or below UVLO threshold, both channels remain disabled regardless of VIN2 status.
What is the purpose of the DA pin on the LT3641IFE#TRPBF?
DA (Pin 18) senses catch diode anode current in the HV channel to implement valley current limiting and protect against shorted outputs. It extends the oscillator cycle when diode current exceeds the valley limit, preventing inductor saturation during faults. This pin must be connected directly to the cathode of the external catch diode - incorrect routing or added impedance compromises current-limit accuracy and fault response.
Does the LT3641IFE#TRPBF support synchronization to an external clock?
Yes - the SYNC pin (Pin 4) accepts an external 350kHz–2.5MHz TTL/CMOS clock signal to synchronize both buck channels. The internal oscillator frequency (set by RT) must be at least 20% lower than the lowest expected SYNC frequency to avoid erratic behavior. SYNC is ignored until FB1 rises above 1.165V, ensuring stable internal operation before external clock takeover.
LT3641IFE#TRPBF Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- -
- Package/Case:
- 28-TSSOP (0.173", 4.40mm Width) 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-TSSOP-EP
LT3641IFE#TRPBF FAQ
1.How can I place an order for LT3641IFE#TRPBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LT3641IFE#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 LT3641IFE#TRPBF reliable?
The price and inventory of LT3641IFE#TRPBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LT3641IFE#TRPBF is usually 5 days.
3.What payment methods are accepted for LT3641IFE#TRPBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LT3641IFE#TRPBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LT3641IFE#TRPBF?
LT3641IFE#TRPBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LT3641IFE#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 LT3641IFE#TRPBF?
For technical support, including LT3641IFE#TRPBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LT3641IFE#TRPBF requirements.
6.How does Aetrix verify that LT3641IFE#TRPBF is sourced from the original manufacturer or authorized distributors?
All LT3641IFE#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 LT3641IFE#TRPBF meets industry standards.
7.What is the process for return or replacement of LT3641IFE#TRPBF?
All LT3641IFE#TRPBF units undergo pre-shipment inspection (PSI). If there is an issue with LT3641IFE#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 LT3641IFE#TRPBF part is unused and in its original packaging.
Return procedure for LT3641IFE#TRPBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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