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Analog Devices Inc. LTC3631IDD#TRPBF
- Part No.:
- LTC3631IDD#TRPBF
- Manufacturer:
- Analog Devices Inc.
- Package:
- 8-WFDFN Exposed Pad
- Datasheet:
-
LTC3631IDD#TRPBF.pdf
- Description:
- IC REG BUCK ADJ 100MA 8DFN
- Quantity:
- Payment:
- Shipping:
Inventory:2,031
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Product details
Overview
LTC3631IDD#TRPBF from Analog Devices (formerly Linear Technology) is a high-voltage, synchronous step-down DC/DC converter with integrated high-side and low-side MOSFETs, delivering up to 100mA output current from a 4.5V–45V input. It operates in Burst Mode® with 12µA no-load quiescent current, features programmable peak current limit (50–225mA), and maintains regulation down to 0% duty cycle for low-dropout operation - ideal for industrial sensor nodes powered by 24V rails or automotive battery-supplied instrumentation.
For engineers reviewing the LTC3631IDD#TRPBF datasheet, LTC3631IDD#TRPBF pinout, LTC3631IDD#TRPBF application, or LTC3631IDD#TRPBF equivalent, key selection criteria include its 45V max input rating with 60V surge tolerance, 0.8V ±1% feedback reference, internal soft-start and RUN pin control with 110mV hysteresis, and compatibility with fixed 3.3V/5V or adjustable output configurations using minimal external components.
Technical Context
The LTC3631IDD#TRPBF implements a hysteretic Burst Mode® control architecture where the feedback comparator (trip at 0.8V ±1%, 5mV hysteresis) disables switching when VFB exceeds the reference, entering 12µA sleep mode until VFB falls 5mV below threshold. Peak inductor current is set via ISET pin (1µA sourced), enabling precise optimization of efficiency across load ranges from 1mA to 100mA.
Its dual-MOSFET synchronous topology eliminates external diode losses, while internal overvoltage lockout (47–52V trip) and undervoltage lockout (3.75–4.5V trip) provide robust protection against transients. The RUN pin (1.17–1.25V enable threshold) and HYST open-drain output allow flexible power sequencing and hysteresis extension in battery-backed or rail-monitoring systems.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 4.5V to 45V - supports direct connection to unregulated 24V industrial or 36V automotive supplies without pre-regulation. |
| No-Load Quiescent Current | 12µA typical - enables multi-year battery life in always-on remote sensors or loop-powered 4–20mA transmitters. |
| Output Current Capability | 100mA maximum - sufficient to power microcontrollers, ADCs, RS-485 transceivers, and analog front-ends in compact embedded systems. |
| Feedback Reference Voltage | 0.800V ±1% - enables accurate output regulation with external resistor dividers; stable over temperature and line variations. |
| Peak Current Limit Range | 50mA to 225mA - programmable via ISET-to-GND resistor to match inductor size and optimize efficiency at light loads. |
| Overvoltage Lockout Threshold | 47V to 52V rising - protects internal switches during 60V transient surges common in automotive load-dump events. |
| Run Pin Enable Threshold | 1.17V to 1.25V rising - allows clean power-up sequencing using simple resistive dividers from VIN or auxiliary rails. |
Pinout & Package
The LTC3631IDD#TRPBF is housed in an 8-lead (3mm × 3mm) plastic DFN package with exposed thermal pad (Pin 9 = GND), optimized for high-power-density layouts and efficient PCB heat dissipation. Thermal resistance θJA = 43°C/W enables reliable operation at full load without forced airflow.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| SW (Pin 1) | Switch Node | Connection point for external inductor; carries high dv/dt switching waveform - requires tight layout and Kelvin grounding to minimize EMI. |
| VIN (Pin 2) | Main Input Supply | High-voltage input rail (4.5–45V); must be decoupled with ≥2.2µF ceramic capacitor directly to GND (Pin 8/9). |
| ISET (Pin 3) | Peak Current Programming | Sources 1µA; resistor to GND sets peak inductor current from 50mA (shorted) to 225mA (open). |
| SS (Pin 4) | Soft-Start Control | Sources 5µA; external capacitor to GND sets ramp time - default internal soft-start is 0.75ms if floating. |
| RUN (Pin 5) | Enable/Shutdown Control | Logic-level input: >1.2V enables regulation; <0.7V forces shutdown (3µA IQ); hysteresis improves noise immunity. |
| VOUT/VFB (Pin 6) | Output Feedback | Connects to regulated output (fixed versions) or divider midpoint (adjustable versions); senses 0.8V reference. |
| HYST (Pin 7) | Run Hysteresis Output | Open-drain logic output pulled low when RUN < 1.2V; used to extend RUN pin hysteresis with external resistor to VIN. |
| GND (Pin 8 + Exposed Pad 9) | Power and Signal Ground | Primary ground return; exposed pad must be soldered to PCB ground plane for thermal and electrical integrity. |
Key Features
| Feature | Design Value |
|---|---|
| Burst Mode® Operation | Maintains regulation at ultra-low loads while drawing only 12µA - critical for energy-harvesting and battery-critical applications. |
| Integrated Synchronous Power Switches | Eliminates external Schottky diode and reduces conduction losses - improves full-load efficiency by ~8% vs asynchronous designs. |
| Programmable Peak Current Limit | Enables use of smaller inductors and capacitors in low-current applications, reducing BOM cost and board area by up to 30%. |
| Precise RUN Pin Threshold with Adjustable Hysteresis | Guarantees controlled start-up under varying input conditions; HYST pin simplifies implementation of custom hysteresis without extra components. |
| Low Dropout Operation (100% Duty Cycle) | Supports output regulation even when VIN approaches VOUT - essential for brownout resilience in wide-input industrial systems. |
Applications
| Industrial Sensor Nodes | 4–20mA Current Loop Transmitters |
|---|---|
Use Scenario: Remote temperature/pressure sensor powered from 24V loop supply with isolated signal conditioning and low-power MCU. IC Role / Device Role / Timing Role: Primary DC/DC regulator converting 24V loop voltage to 3.3V for microcontroller, ADC, and signal chain - operating continuously at <1mA average load. Use Value: 12µA quiescent current extends battery life beyond 10 years; Burst Mode® ensures stable 3.3V output despite highly variable sensor activity. | Use Scenario: Two-wire field transmitter delivering calibrated 4–20mA output while powering internal circuitry from same loop. IC Role / Device Role / Timing Role: High-efficiency buck converter supplying regulated 5V to op-amps, DACs, and loop driver - must operate down to 8V loop compliance voltage. Use Value: 4.5V minimum input and 100% duty cycle capability maintain regulation at lowest loop voltages; 60V surge tolerance withstands cable ESD events. |
| Automotive Body Electronics | Portable Test Equipment |
Use Scenario: Door module or lighting controller powered from 12V battery with load-dump and cold-crank resilience requirements. IC Role / Device Role / Timing Role: Secondary power rail generator providing 5V for CAN transceiver and microcontroller - must survive 60V transients and start reliably at 4.5V. Use Value: Integrated 60V surge protection and precise UVLO/OVLO eliminate need for external TVS or supervisor ICs - reduces component count and board space. | Use Scenario: Handheld multimeter or oscilloscope with Li-ion battery pack (8.4V–12.6V) powering analog front-end and display backlight. IC Role / Device Role / Timing Role: Step-down regulator delivering 3.3V to MCU and 5V to display driver - must sustain full load during measurement bursts while minimizing standby drain. Use Value: Programmable peak current limit allows optimal inductor sizing for both burst efficiency and continuous operation; SS pin enables smooth startup without input droop. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar step-down converter applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LT8609SIS8E#TRPBF | Higher 2.5A output, 3V–42V input, 2.5µA IQ, but requires external compensation and has larger MSOP-8 footprint. | Targeted at higher-current applications; lacks programmable peak current limit and integrated soft-start flexibility. | Select when >100mA output or tighter EMI control (Silent Switcher®) is required; not drop-in due to different pinout and compensation needs. |
| TPS54202DRCT | 2A output, 4.5V–28V input, 26µA IQ, uses external MOSFETs, requires full compensation network. | Designed for cost-sensitive, medium-current applications; no integrated switches or Burst Mode® - lower light-load efficiency. | Choose for higher output current with discrete FET control; avoid when ultra-low IQ or minimal external parts are mandatory. |
Compared with LT8609SIS8E#TRPBF and TPS54202DRCT, the LTC3631IDD#TRPBF delivers superior light-load efficiency and smallest solution size for ≤100mA applications, with no external compensation and fewer passive components - making it optimal for space-constrained, battery- or loop-powered systems where standby current dominates lifetime cost.
Availability
LTC3631IDD#TRPBF is available at Aetrix Electronics and suitable for industrial sensor nodes, 4–20mA current loop transmitters, and automotive body electronics requiring stable component supply, long-term lifecycle support, and guaranteed traceable sourcing.
Supply support for LTC3631IDD#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, Inc. (acquired Linear Technology in 2017) is a global leader in high-performance analog, mixed-signal, and power management semiconductors, serving industrial, automotive, communications, and healthcare markets.
The LTC3631 belongs to Linear's high-voltage monolithic DC/DC converter product line, designed specifically for rugged, low-quiescent-current regulation in harsh environments - emphasizing reliability, integration, and ease of use in distributed power architectures.
FAQ
What is the maximum input voltage the LTC3631IDD#TRPBF can withstand without damage?
The LTC3631IDD#TRPBF has an absolute maximum VIN rating of 60V and includes internal overvoltage lockout that disables switching above 47–52V. This allows safe operation during automotive load-dump transients or industrial power surges while maintaining regulation from 4.5V to 45V - the specified functional input range. The device remains latched off until VIN returns within the operational window.
Does the LTC3631IDD#TRPBF require external compensation components?
No, the LTC3631IDD#TRPBF uses a proprietary hysteretic Burst Mode® control architecture that requires no external compensation components. Its internal feedback loop is fully self-contained, enabling stable regulation with only three external parts for fixed-output versions: input capacitor, output capacitor, and inductor - significantly simplifying design and reducing bill-of-materials cost.
How does the ISET pin on the LTC3631IDD#TRPBF affect output current capability?
The ISET pin on the LTC3631IDD#TRPBF sources a precise 1µA current; connecting a resistor from ISET to GND sets the peak inductor current between 50mA (R = 0Ω) and 225mA (R = open). Since maximum average output current equals half the peak current in this architecture, the ISET resistor directly determines usable load capacity - e.g., a 500kΩ resistor yields ~112mA peak and ~56mA average output.
Can the LTC3631IDD#TRPBF operate with 100% duty cycle, and why is that important?
Yes, the LTC3631IDD#TRPBF supports 100% duty cycle operation, meaning it can maintain regulation even when input voltage drops to near the output voltage level. This is critical in automotive cold-crank scenarios (VIN dips to ~4.5V) or industrial brownouts, ensuring uninterrupted power to downstream circuitry without dropout - a key advantage over many competing buck regulators with minimum off-time limitations.
What package type and thermal characteristics apply to the LTC3631IDD#TRPBF?
The LTC3631IDD#TRPBF uses an 8-lead 3mm × 3mm plastic DFN package with exposed thermal pad (Pin 9 = GND). Its thermal resistance is θJA = 43°C/W and θJC = 3°C/W, enabling reliable 100mA operation on standard FR-4 PCBs with adequate copper pour. The exposed pad must be soldered to the ground plane to achieve rated performance and prevent thermal shutdown.
LTC3631IDD#TRPBF Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- -
- Package/Case:
- 8-WFDFN Exposed Pad
- Packaging:
- Tape & Reel (TR)
- Product Status:
- Active
- Function:
- Step-Down
- Output Configuration:
- Positive or Negative
- Topology:
- Buck
- Output Type:
- Adjustable
- Number of Outputs:
- 1
- Voltage - Input (Min):
- 4.5V
- Voltage - Input (Max):
- 45V
- Voltage - Output (Min/Fixed):
- 0.8V
- Voltage - Output (Max):
- 45V
- Current - Output:
- 100mA
- Frequency - Switching:
- -
- Synchronous Rectifier:
- Yes
- Operating Temperature:
- -40°C ~ 125°C (TJ)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 8-DFN (3x3)
LTC3631IDD#TRPBF FAQ
1.How can I place an order for LTC3631IDD#TRPBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LTC3631IDD#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 LTC3631IDD#TRPBF reliable?
The price and inventory of LTC3631IDD#TRPBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LTC3631IDD#TRPBF is usually 5 days.
3.What payment methods are accepted for LTC3631IDD#TRPBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LTC3631IDD#TRPBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LTC3631IDD#TRPBF?
LTC3631IDD#TRPBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LTC3631IDD#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 LTC3631IDD#TRPBF?
For technical support, including LTC3631IDD#TRPBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LTC3631IDD#TRPBF requirements.
6.How does Aetrix verify that LTC3631IDD#TRPBF is sourced from the original manufacturer or authorized distributors?
All LTC3631IDD#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 LTC3631IDD#TRPBF meets industry standards.
7.What is the process for return or replacement of LTC3631IDD#TRPBF?
All LTC3631IDD#TRPBF units undergo pre-shipment inspection (PSI). If there is an issue with LTC3631IDD#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 LTC3631IDD#TRPBF part is unused and in its original packaging.
Return procedure for LTC3631IDD#TRPBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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