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Analog Devices Inc. LT3641EFE#TRPBF
- Part No.:
- LT3641EFE#TRPBF
- Manufacturer:
- Analog Devices Inc.
- Package:
- 28-TSSOP (0.173", 4.40mm Width) Exposed Pad
- Datasheet:
-
LT3641EFE#TRPBF.pdf
- Description:
- IC REG BUCK ADJ DL 28TSSOP
- Quantity:
- Payment:
- Shipping:
Inventory:1,673
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Product details
Overview
LT3641EFE#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. Used in automotive ECU power rails requiring transient robustness and microcontroller supervision.
For engineers reviewing the LT3641EFE#TRPBF datasheet, LT3641EFE#TRPBF pinout, LT3641EFE#TRPBF application, or LT3641EFE#TRPBF equivalent, key selection criteria include its dual-input voltage ranges (4–42V HV + 2.5–5.5V LV), programmable reset/watchdog timing via external capacitors, 290μA quiescent current, thermal shutdown, and 28-pin TSSOP package with exposed GND pad.
Technical Context
The LT3641EFE#TRPBF integrates two independent current-mode PWM controllers sharing a single adjustable oscillator (350kHz–2.5MHz). The high-voltage channel uses a nonsynchronous NPN switch with 2.4A peak current limit and 55V transient protection; the low-voltage channel employs synchronous NMOS/PMOS switches with 1.1A combined current capability and 200mΩ/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 inter-pulse intervals fall outside tWDL (1.68–2.2ms) or exceed tWDU (27–35ms) -both configured via CWDT capacitor.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| HV Input Range | 4V to 42V continuous, with 55V nonrepetitive transient tolerance - enables direct connection to automotive battery without external TVS. |
| LV Input Range | 2.5V to 5.5V - supports post-regulation from HV output or independent 3.3V/5V supply. |
| Switching Frequency | Adjustable 350kHz–2.5MHz via RT resistor - allows optimization of inductor size vs. efficiency (e.g., 2MHz enables 2.2μH HV inductor). |
| Quiescent Current | 290μA typical - sustains low-power sleep modes in always-on automotive systems. |
| FB1 Reference | 1.265V ±1.2% over –40°C to 125°C - sets precise 5V output with 1% resistors (R1=100kΩ, R2=301kΩ). |
| FB2 Reference | 600mV ±2.5% over –40°C to 125°C - enables accurate 3.3V output using R3=49.9kΩ, R4=226kΩ divider. |
| Shutdown Current | <1μA - meets stringent automotive off-state leakage requirements. |
Pinout & Package
LT3641EFE#TRPBF is housed in a thermally enhanced 28-lead plastic TSSOP package (FE) with exposed GND pad (Pin 29), θJA = 30°C/W. The package requires soldering the exposed pad to PCB ground for optimal thermal performance and EMI control.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| FB1 (Pin 6) | High-voltage feedback reference node | Regulated to 1.265V; connects to resistor divider tap for precise VOUT1 setting (e.g., 5V). |
| FB2 (Pin 1) | Low-voltage feedback reference node | Regulated to 600mV; connects to resistor divider tap for precise VOUT2 setting (e.g., 3.3V). |
| 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) | Power-on reset timer capacitor node | Charges to set RST1/RST2 assertion time (e.g., 220pF → 9.5ms timeout). |
| CWDT (Pin 11) | Watchdog timer capacitor node | Charges to define watchdog window boundaries (e.g., 820pF → tWDL=2ms, tWDU=32ms). |
| WDI (Pin 14) | Watchdog input | Accepts μP pulses; falling edges reset watchdog timer - must meet 300ns min pulse width. |
| WDO (Pin 10) | Watchdog output | Open-drain flag asserted when WDI pulses violate window; pulls low to reset microcontroller. |
| PGOOD2 (Pin 2) | Low-voltage power-good indicator | Open-drain output active when FB2 ≥550mV + hysteresis - signals stable 3.3V rail. |
Key Features
| Feature | Design Value |
|---|---|
| Dual independent buck regulation | Enables compact dual-rail power architecture: HV channel powers core logic (5V), LV channel powers I/O/peripherals (3.3V), eliminating need for secondary LDOs. |
| Burst Mode® operation | Maintains >85% efficiency at 1mA load on both channels - critical for battery-backed automotive modules during sleep. |
| Programmable window watchdog | Prevents system hang from stuck or runaway firmware by detecting both too-frequent and too-sparse WDI pulses - higher reliability than standard timeout watchdogs. |
| Input transient protection to 55V | Withstands ISO 7637-2 Pulse 1 (–150V) and Pulse 5a (75V) when paired with external clamp - reduces need for upstream TVS diodes. |
| Thermally enhanced TSSOP | Exposed GND pad lowers junction-to-board thermal resistance to 8°C/W - supports 1.3A HV + 1.1A LV continuous operation at 85°C ambient. |
Applications
| Automotive Body Control Module (BCM) | Industrial PLC I/O Power |
|---|---|
Use Scenario: Powering MCU, CAN transceiver, and sensor interface circuitry in a vehicle door module with cold-crank (4.5V) and load-dump (40V) conditions. IC Role / Device Role / Timing Role: LT3641EFE#TRPBF provides regulated 5V (MCU core) and 3.3V (CAN PHY/sensors) while monitoring MCU health via WDI/WDO and asserting reset during brownout. Use Value: Single-chip solution eliminates discrete supervisor IC and reduces BOM count by 3 components versus dual-DC/DC + external reset IC. | Use Scenario: Generating isolated 5V and 3.3V rails for analog input conditioning and digital isolation in a DIN-rail mounted programmable logic controller. IC Role / Device Role / Timing Role: LT3641EFE#TRPBF acts as primary DC/DC converter with built-in POR and watchdog, interfacing directly with industrial MCU's reset and debug pins. Use Value: 55V transient rating allows direct connection to 24VDC field bus without additional protection, simplifying front-end design. |
| Medical Infusion Pump Controller | Ruggedized Telematics Unit |
Use Scenario: Supplying safety-critical 5V logic and 3.3V display backlight drivers in a battery-operated infusion pump requiring >10-year field reliability. IC Role / Device Role / Timing Role: LT3641EFE#TRPBF delivers tightly regulated outputs while continuously validating MCU liveness via windowed watchdog - mandatory for IEC 62304 Class C software. Use Value: Programmable CPOR/CWDT capacitors enable exact timing alignment with pump motor startup sequence and communication handshake timeouts. | Use Scenario: Powering GPS/GNSS receiver, cellular modem, and ARM Cortex-A processor in an in-vehicle telematics unit exposed to wide temperature (-40°C to 105°C) and vibration. IC Role / Device Role / Timing Role: LT3641EFE#TRPBF serves as main power management IC, using EN/UVLO for controlled startup and PGOOD2 to enable modem only after stable 3.3V is established. Use Value: 290μA quiescent current extends battery backup runtime during ignition-off periods without compromising reset integrity. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar dual-buck regulator with supervision applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LTC3642EFE#TRPBF | Same pinout, identical features, but rated for –40°C to 150°C (H-grade); 10% higher HV current limit (1.45A vs 1.3A). | Required for under-hood automotive applications exceeding 125°C junction temperature. | Select LTC3642EFE#TRPBF when operating ambient exceeds 105°C or extended temperature qualification is mandated. |
| TPS65270QPWPRQ1 | Automotive-qualified dual buck (3A/2A), no integrated watchdog/POR; requires external supervisor IC for reset timing. | Higher current capability but adds board area and cost for external reset/watchdog components. | Choose TPS65270QPWPRQ1 only when >1.3A HV output current is required and external supervision is acceptable. |
Compared with LTC3642EFE#TRPBF, LT3641EFE#TRPBF offers identical functionality at lower cost and temperature grade, making it optimal for cabin-mounted ECUs. Versus TPS65270QPWPRQ1, LT3641EFE#TRPBF integrates supervision functions, reducing component count and validation effort despite lower current rating.
Availability
LT3641EFE#TRPBF is available at Aetrix Electronics and suitable for automotive electronic control units, industrial PLC power supplies, and medical infusion pump controllers requiring stable component supply across extended temperature and long product lifecycles.
Supply support for LT3641EFE#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 industrial and automotive applications.
LT3641EFE#TRPBF belongs to Linear's monolithic DC/DC regulator family designed specifically for space-constrained, high-reliability power systems requiring integrated supervision - targeting automotive body electronics and industrial control where transient immunity and functional safety are critical.
FAQ
What is the maximum input voltage the LT3641EFE#TRPBF can withstand without damage?
The LT3641EFE#TRPBF has an absolute maximum VIN rating of 55V for nonrepetitive 1-second transients, such as automotive load dump events. Continuous operation is rated up to 42V. Exceeding 55V even briefly may cause permanent damage. For sustained 48V system designs, external clamping is required before the LT3641EFE#TRPBF input.
How do I configure the LT3641EFE#TRPBF for 5V and 3.3V outputs?
To set VOUT1 = 5V, connect a resistor divider from VOUT1 to GND with R1 = 100kΩ and R2 = 301kΩ to FB1 (targeting 1.265V). For VOUT2 = 3.3V, use R3 = 49.9kΩ and R4 = 226kΩ to FB2 (targeting 600mV). All resistors must be 1% tolerance; R1 ≤ 100kΩ and R3 ≤ 50kΩ to minimize noise sensitivity per the LT3641EFE#TRPBF datasheet.
Does the LT3641EFE#TRPBF require an external catch diode on the high-voltage channel?
Yes, the LT3641EFE#TRPBF high-voltage channel is nonsynchronous and requires an external Schottky catch diode (e.g., MBR0530) connected between SW1 and GND. The DA pin monitors diode current for valley-current limiting. The low-voltage channel is fully synchronous and needs no external diode - its internal NMOS/PMOS switches handle freewheeling.
Can the LT3641EFE#TRPBF watchdog operate independently of the power-on reset function?
Yes. The LT3641EFE#TRPBF watchdog timer starts only after RST2 is released (i.e., after FB2 reaches regulation), and its timing is set solely by the CWDT capacitor. The CPOR capacitor controls only RST1/RST2 assertion time and WDO initial timeout - it does not affect ongoing watchdog window detection. This allows independent tuning of startup sequencing and runtime supervision.
What thermal derating applies to the LT3641EFE#TRPBF in a 2-layer PCB design?
In a standard 2-layer PCB with 1oz copper and no thermal vias, the LT3641EFE#TRPBF's 28-pin TSSOP package exhibits θJA ≈ 55°C/W (vs. 30°C/W on 4-layer boards). At 85°C ambient, this limits total dissipation to ~1.1W - corresponding to ~1.0A HV + 0.8A LV simultaneous operation. Use ≥6 thermal vias under the exposed pad and 2oz inner layers to restore full rated current.
LT3641EFE#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
LT3641EFE#TRPBF FAQ
1.How can I place an order for LT3641EFE#TRPBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LT3641EFE#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 LT3641EFE#TRPBF reliable?
The price and inventory of LT3641EFE#TRPBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LT3641EFE#TRPBF is usually 5 days.
3.What payment methods are accepted for LT3641EFE#TRPBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LT3641EFE#TRPBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LT3641EFE#TRPBF?
LT3641EFE#TRPBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LT3641EFE#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 LT3641EFE#TRPBF?
For technical support, including LT3641EFE#TRPBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LT3641EFE#TRPBF requirements.
6.How does Aetrix verify that LT3641EFE#TRPBF is sourced from the original manufacturer or authorized distributors?
All LT3641EFE#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 LT3641EFE#TRPBF meets industry standards.
7.What is the process for return or replacement of LT3641EFE#TRPBF?
All LT3641EFE#TRPBF units undergo pre-shipment inspection (PSI). If there is an issue with LT3641EFE#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 LT3641EFE#TRPBF part is unused and in its original packaging.
Return procedure for LT3641EFE#TRPBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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