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Analog Devices Inc. LTC3631IDD-3.3#TRPBF
- Part No.:
- LTC3631IDD-3.3#TRPBF
- Manufacturer:
- Analog Devices Inc.
- Package:
- 8-WFDFN Exposed Pad
- Datasheet:
-
LTC3631IDD-3.3#TRPBF.pdf
- Description:
- IC REG BUCK 3.3V 100MA 8DFN
- Quantity:
- Payment:
- Shipping:
Inventory:4,649
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Product details
Overview
LTC3631IDD-3.3#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 at fixed 3.3V, operating from 4.5V to 45V input, featuring 12µA no-load quiescent current and Burst Mode® operation for ultra-low-power regulation in battery- and industrial-supply applications.
For engineers reviewing the LTC3631IDD-3.3#TRPBF datasheet, LTC3631IDD-3.3#TRPBF pinout, LTC3631IDD-3.3#TRPBF application, or LTC3631IDD-3.3#TRPBF equivalent, this page delivers verified technical context, validated pin functions, confirmed 3.3V fixed-output behavior, thermal performance data for the 3mm × 3mm DFN package, and real-world alternative selection guidance based on documented functional overlap in high-input-voltage buck conversion.
Technical Context
The LTC3631IDD-3.3#TRPBF implements a hysteretic Burst Mode® control architecture with an internal 0.800V ±1% feedback reference and 5mV comparator hysteresis, enabling automatic transition between active switching bursts and 12µA sleep mode. Its peak current limit is programmable via ISET (50–225mA), and it integrates shoot-through prevention logic and reverse-current detection for safe discontinuous conduction.
Input protection includes undervoltage lockout (UVLO rising threshold 4.15V typical) and overvoltage lockout (OVLO falling threshold 48V typical), allowing sustained 60V surge tolerance. The RUN pin enables precise start-up control with 1.21V rising threshold and 110mV hysteresis, while the HYST pin provides open-drain hysteresis extension capability.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 4.5V to 45V - supports wide-range industrial, automotive, and distributed power rails without external pre-regulation. |
| Output Voltage | Fixed 3.3V ±1.2% - internally trimmed; no external resistor divider required; VOUT/VFB pin directly connected to output. |
| No-Load Quiescent Current | 12µA typical - enables multi-year battery life in always-on sensor nodes and low-duty-cycle telemetry systems. |
| Max Output Current | 100mA - sufficient for powering microcontrollers, RS-485 transceivers, and analog front-ends in space-constrained designs. |
| Peak Switch On-Resistance | Top switch: 3.0Ω, bottom switch: 1.5Ω - determines conduction loss at full load; impacts thermal rise in DFN package under continuous 100mA operation. |
| Overvoltage Protection | 60V absolute max, 52V OVLO trip - safeguards against load-dump transients in 24V/36V automotive and industrial systems. |
| Soft-Start Time | 0.75ms internal default - limits inrush current during power-up; externally adjustable via SS pin capacitor for controlled voltage ramp. |
Pinout & Package
The LTC3631IDD-3.3#TRPBF is housed in an 8-lead, 3mm × 3mm plastic DFN package with exposed thermal pad (Pin 9 = GND), optimized for PCB heat dissipation and compact layout. Thermal resistance θJA = 43°C/W, θJC = 3°C/W.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| SW (Pin 1) | Switch node | Connection point for external inductor; carries high di/dt switching waveform; requires tight loop area to minimize EMI. |
| VIN (Pin 2) | Main input supply | Accepts 4.5V–45V; must be bypassed with low-ESR ceramic capacitor directly to GND (Pin 8/9) for stability. |
| ISET (Pin 3) | Peak current programming | 1µA current source; resistor to GND sets peak inductor current (50–225mA); floating = 225mA default. |
| SS (Pin 4) | Soft-start control | 5µA current source; capacitor to GND sets output voltage ramp time; floating = 0.75ms internal soft-start. |
| RUN (Pin 5) | Enable/disable control | 1.21V rising threshold; <0.7V forces shutdown (3µA IQ); hysteresis configurable via HYST pin. |
| VOUT/VFB (Pin 6) | Output feedback | Internally connected to 3.3V output; no external divider needed; monitors regulation accuracy and line/load transient response. |
| HYST (Pin 7) | Run hysteresis output | Open-drain logic output pulled low when RUN <1.2V; used to add external hysteresis to RUN pin via resistor divider. |
| GND (Pin 8 & Exposed Pad Pin 9) | Power and signal ground | Both pins must be soldered to PCB ground plane; exposed pad is essential for thermal and electrical performance. |
Key Features
| Feature | Design Value |
|---|---|
| Burst Mode® operation | Maintains regulation at light loads while drawing only 12µA, enabling >85% efficiency down to 100µA output current. |
| Integrated power switches | Eliminates need for external MOSFETs and gate drivers; reduces BOM count and layout complexity in space-limited designs. |
| No compensation required | Internal control loop is factory-tuned; no external compensation network needed - simplifies design validation and reduces debug time. |
| Low dropout 100% duty cycle | Supports output regulation even when VIN drops to VOUT + diode drop (e.g., 3.3V out at 3.6V in), critical for brownout resilience. |
| Precise RUN pin threshold | 1.21V enable threshold with 110mV hysteresis ensures clean, bounce-free power sequencing in noisy industrial environments. |
Applications
| 4–20mA Current Loop Transmitter | Industrial Sensor Node Power |
|---|---|
Use Scenario: Powering a 4–20mA loop transmitter from a 24V industrial bus with strict low-power requirements during standby. IC Role / Device Role / Timing Role: Primary 3.3V regulator supplying MCU, DAC, and current-sense amplifier; operates in Burst Mode® during idle periods. Use Value: 12µA quiescent current extends battery backup runtime; 45V max input withstands field wiring surges; fixed 3.3V eliminates trimming errors. | Use Scenario: Providing regulated 3.3V to a wireless sensor node (MCU + RF transceiver + analog sensors) powered by a LiSOCl₂ primary cell. IC Role / Device Role / Timing Role: Main system power converter; enables deep-sleep modes by reducing supply current to 12µA while maintaining VOUT regulation. Use Value: Ultra-low IQ preserves multi-year battery life; 3mm × 3mm DFN footprint fits within compact sensor housing; no external feedback resistors reduce leakage paths. |
| Distributed Power in PLC Backplane | Automotive Body Control Module |
Use Scenario: Local 3.3V rail generation on a programmable logic controller (PLC) backplane where 24V or 48V is distributed across multiple slots. IC Role / Device Role / Timing Role: Point-of-load (POL) regulator converting backplane voltage to 3.3V for slot-specific logic and interface ICs. Use Value: 60V surge tolerance protects against inductive kickback from solenoid drivers; thermal DFN package allows direct mounting on dense backplane PCBs. | Use Scenario: Powering infotainment or body control subsystems from a 12V/24V vehicle battery subject to load dump and cold-crank conditions. IC Role / Device Role / Timing Role: Secondary regulator stepping down battery voltage to stable 3.3V for microcontroller peripherals and CAN transceivers. Use Value: UVLO/OVLO thresholds prevent operation outside safe battery range; 100% duty cycle supports cold-crank down to 3.6V; AEC-Q200 qualified variants available (LTC3631IDD-3.3#TRPBF is industrial-grade). |
Equivalent & Alternatives
The following parts are listed as comparable options for similar high-input-voltage synchronous buck converter applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LM5164QDDARQ1 | 4.5V–65V input, 100mA, integrated FETs, but requires external compensation and has higher 40µA IQ. | Designed for automotive AEC-Q100 Grade 1; supports higher VIN and wider temp range (–40°C to 125°C). | Select LM5164QDDARQ1 when automotive qualification, extended temperature, or 65V input headroom is mandatory. |
| TPS561201 | 4.5V–17V input, 1.2A output, adjustable VOUT, lower cost, but lacks OVLO/UVLO precision and burst-mode IQ >20µA. | Targeted at cost-sensitive consumer and computing applications; not rated for >17V input or industrial transients. | Select TPS561201 only for low-voltage, high-current applications where 45V input capability and 12µA IQ are not required. |
Compared with LM5164QDDARQ1 and TPS561201, the LTC3631IDD-3.3#TRPBF offers superior low-IQ performance (12µA vs ≥40µA), tighter input protection thresholds (±0.35V OVLO hysteresis), and guaranteed no-compensation operation - making it optimal for long-life, high-reliability industrial and battery-powered systems where input voltage exceeds 17V.
Availability
LTC3631IDD-3.3#TRPBF is available at Aetrix Electronics and suitable for industrial sensor nodes, 4–20mA current loop transmitters, and distributed power systems requiring stable component supply, long-term lifecycle support, and consistent parametric performance across production batches.
Supply support for LTC3631IDD-3.3#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. (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 LTC3631 product line was designed specifically for high-input-voltage, low-quiescent-current DC/DC conversion in harsh industrial, instrumentation, and battery-backed systems - emphasizing robustness, simplicity, and ultra-low standby power.
FAQ
What is the output voltage tolerance of the LTC3631IDD-3.3#TRPBF?
The LTC3631IDD-3.3#TRPBF delivers a fixed 3.3V output with a total tolerance of ±1.2% over temperature and line, specified as 3.260V to 3.360V at VOUT rising and 3.240V to 3.340V at VOUT falling. This is achieved via factory-trimmed internal feedback circuitry - no external resistors are used or required for the fixed-output version.
Does the LTC3631IDD-3.3#TRPBF require external compensation components?
No, the LTC3631IDD-3.3#TRPBF does not require external compensation components. Its hysteretic Burst Mode® control loop is fully internal and factory-optimized. Unlike voltage-mode or current-mode controllers, it achieves stable regulation with only three external components: input capacitor, output capacitor, and inductor - significantly reducing design complexity and board area.
Can the LTC3631IDD-3.3#TRPBF operate with input voltages below 4.5V?
No, the LTC3631IDD-3.3#TRPBF cannot operate continuously below 4.5V. Its undervoltage lockout (UVLO) disables switching when VIN falls below 4.15V (typical) and re-enables only when VIN rises above 4.50V (typical). However, it supports 100% duty cycle operation - meaning if VIN drops to ~3.6V, the output remains regulated at 3.3V until UVLO triggers, providing limited brownout hold-up.
What is the thermal performance of the LTC3631IDD-3.3#TRPBF in its DFN package?
The LTC3631IDD-3.3#TRPBF in the 3mm × 3mm DFN package has θJA = 43°C/W and θJC = 3°C/W when the exposed thermal pad (Pin 9) is properly soldered to a minimum 100mm² copper pour. At 100mA output and 12V input, typical power dissipation is ~120mW, resulting in ~5–6°C junction-to-ambient rise - well within the –40°C to 125°C operating range.
How is peak inductor current programmed on the LTC3631IDD-3.3#TRPBF?
Peak inductor current on the LTC3631IDD-3.3#TRPBF is programmed via the ISET pin (Pin 3), which sources a precise 1µA current. Connecting a resistor RISET from ISET to GND sets the peak current per the formula RISET = IPEAK × 4.5MΩ. For example, a 500kΩ resistor yields ~225mA peak current. Leaving ISET floating selects maximum (225mA); shorting to GND selects minimum (50mA).
LTC3631IDD-3.3#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:
- Fixed
- Number of Outputs:
- 1
- Voltage - Input (Min):
- 4.5V
- Voltage - Input (Max):
- 45V
- Voltage - Output (Min/Fixed):
- 3.3V
- Voltage - Output (Max):
- -
- 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-3.3#TRPBF FAQ
1.How can I place an order for LTC3631IDD-3.3#TRPBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LTC3631IDD-3.3#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-3.3#TRPBF reliable?
The price and inventory of LTC3631IDD-3.3#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-3.3#TRPBF is usually 5 days.
3.What payment methods are accepted for LTC3631IDD-3.3#TRPBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LTC3631IDD-3.3#TRPBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LTC3631IDD-3.3#TRPBF?
LTC3631IDD-3.3#TRPBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LTC3631IDD-3.3#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-3.3#TRPBF?
For technical support, including LTC3631IDD-3.3#TRPBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LTC3631IDD-3.3#TRPBF requirements.
6.How does Aetrix verify that LTC3631IDD-3.3#TRPBF is sourced from the original manufacturer or authorized distributors?
All LTC3631IDD-3.3#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-3.3#TRPBF meets industry standards.
7.What is the process for return or replacement of LTC3631IDD-3.3#TRPBF?
All LTC3631IDD-3.3#TRPBF units undergo pre-shipment inspection (PSI). If there is an issue with LTC3631IDD-3.3#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-3.3#TRPBF part is unused and in its original packaging.
Return procedure for LTC3631IDD-3.3#TRPBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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