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Analog Devices Inc. LTC3631EMS8E-3.3#PBF
- Part No.:
- LTC3631EMS8E-3.3#PBF
- Manufacturer:
- Analog Devices Inc.
- Package:
- 8-TSSOP, 8-MSOP (0.118", 3.00mm Width) Exposed Pad
- Datasheet:
-
LTC3631EMS8E-3.3#PBF.pdf
- Description:
- IC REG BUCK 3.3V 100MA 8MSOP
- Quantity:
- Payment:
- Shipping:
Inventory:2,698
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Product details
Overview
LTC3631EMS8E-3.3#PBF 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 at a fixed 3.3V output, operating from 4.5V to 45V input, and drawing only 12µA quiescent current in Burst Mode® operation - ideal for industrial control supplies and battery-operated devices requiring ultra-low standby power.
For engineers reviewing the LTC3631EMS8E-3.3#PBF datasheet, LTC3631EMS8E-3.3#PBF pinout, LTC3631EMS8E-3.3#PBF application, or LTC3631EMS8E-3.3#PBF equivalent, this page delivers verified technical context, validated pin functions, confirmed 3.3V fixed-output behavior, thermal performance data for the MS8E package, and real-world alternative selection guidance grounded in manufacturer-specified compatibility.
Technical Context
The LTC3631EMS8E-3.3#PBF implements a hysteretic Burst Mode® control architecture with an internal 0.800V ±1% feedback reference, enabling regulation without external compensation. Its peak current limit is programmable via the ISET pin (50mA–225mA), directly determining maximum average output current (up to 112mA).
It integrates both high-side (P-channel) and low-side (N-channel) MOSFETs with typical on-resistances of 3.0Ω and 1.5Ω, respectively, and features precise RUN pin threshold (1.21V rising / 1.10V falling) with 110mV hysteresis, plus internal soft-start (0.75ms) and external soft-start capability via the SS pin.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Output Voltage | Fixed 3.3V ±1.2% (3.26V–3.36V over temperature), eliminating need for external feedback divider. |
| Input Voltage Range | 4.5V to 45V DC - supports wide industrial and automotive supply rails; includes 60V surge tolerance via overvoltage lockout. |
| Max Output Current | 100mA continuous load - limited by internal power switches and thermal design of MS8E package (θJA = 40°C/W). |
| Quiescent Current | 12µA typical in Burst Mode® - enables >1-year battery life in 10µA-systems with intermittent wake-up. |
| Feedback Reference | 0.800V ±1% (–40°C to 125°C) - sets output accuracy and enables precise regulation across line/load/temperature. |
| Peak Current Limit | Programmable 50mA–225mA via ISET resistor - allows optimization of inductor size, ripple, and efficiency for specific load profiles. |
| Shutdown Current | 3µA max - achieved when RUN pin < 0.7V, enabling deep system-level power gating. |
Pinout & Package
Package: 8-lead plastic MSOP (MS8E), 3mm × 3mm footprint, 0.75mm profile, with exposed GND pad (Pin 9) requiring PCB soldering for thermal and electrical integrity (θJC = 5°C–10°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 layout and Kelvin grounding. |
| VIN (Pin 2) | Main input supply | Accepts 4.5V–45V; must be bypassed with low-ESR ceramic capacitor directly to GND (Pin 8/9) to suppress high-frequency noise. |
| ISET (Pin 3) | Peak current programming input | Sources 1µA; resistor to GND sets peak inductor current (50–225mA); floating = 225mA, shorted = 50mA. |
| SS (Pin 4) | Soft-start control | Sources 5µA; external capacitor to GND sets ramp time (default internal = 0.75ms); controls inrush and input droop. |
| RUN (Pin 5) | Enable/disable control | Active-high logic: >1.21V enables regulation; <0.7V forces shutdown (3µA IQ); hysteresis improves noise immunity. |
| VOUT/VFB (Pin 6) | Output voltage sense / feedback | Internally connected to 3.3V output in fixed versions; serves as error amplifier input referenced to 0.800V. |
| HYST (Pin 7) | Run hysteresis open-drain output | Pulled low when RUN < 1.2V; used externally to increase RUN pin hysteresis via resistor divider feedback. |
| GND (Pin 8 & Exposed Pad Pin 9) | Power and signal ground | Primary return path for VIN, SW, and internal circuitry; exposed pad must be soldered to PCB ground plane for thermal management. |
Key Features
| Feature | Design Value |
|---|---|
| No external compensation required | Internal hysteretic control loop eliminates need for loop compensation components - reduces BOM count and layout sensitivity. |
| Low dropout operation | 100% duty cycle capability - maintains regulation down to VIN ≈ VOUT, critical for brownout resilience in wide-input systems. |
| Integrated power switches | Monolithic P-channel high-side + N-channel low-side MOSFETs - eliminates external FETs and gate drivers, simplifying design and reducing footprint. |
| Precise RUN pin threshold | 1.21V rising / 1.10V falling with 110mV hysteresis - enables reliable power sequencing and robust start-up under noisy supply conditions. |
| Thermally enhanced MS8E package | θJA = 40°C/W with exposed GND pad - supports 100mA continuous output at +85°C ambient without forced air or heatsink. |
Applications
| 4–20mA Current Loops | Industrial Control Supplies |
|---|---|
Use Scenario: Powering loop-powered field transmitters in hazardous area instrumentation where supply headroom is limited and standby current must be minimized. IC Role / Device Role / Timing Role: Primary 3.3V regulator sourcing sensor signal conditioning and DAC circuitry while maintaining compliance with 4–20mA loop voltage drop constraints. Use Value: 12µA quiescent current ensures sufficient margin below 4mA loop minimum, preserving analog signal integrity and enabling true two-wire operation. |
Use Scenario: Providing isolated 3.3V bias for PLC I/O modules, valve positioners, and HART modems operating from unregulated 24V DC rails subject to surges and brownouts. IC Role / Device Role / Timing Role: Robust front-end DC/DC converter handling 45V transients and 60V surges, with UVLO/OVLO protecting downstream logic and analog circuitry. Use Value: 4.5V–45V input range and 60V surge tolerance eliminate need for upstream TVS or LDO pre-regulation, reducing component count and failure points. |
| Distributed Power Systems | Battery-Operated Devices |
Use Scenario: Local point-of-load regulation in distributed architectures where centralized 24V or 48V bus powers multiple subsystems with varying voltage requirements. IC Role / Device Role / Timing Role: Compact, thermally efficient 3.3V step-down stage placed near microcontrollers, ADCs, or communication ICs to minimize IR drop and noise coupling. Use Value: MS8E package (3mm × 3mm) and no-compensation design enable dense placement with minimal PCB area and thermal derating concerns. |
Use Scenario: Long-life portable instruments (e.g., handheld multimeters, gas detectors) powered by primary lithium or alkaline cells with declining voltage profiles. IC Role / Device Role / Timing Role: High-efficiency buck converter sustaining 3.3V output down to 4.5V input, extending usable battery capacity beyond linear regulators. Use Value: Burst Mode® efficiency >85% at 1mA load and 12µA sleep current maximize runtime in intermittently active measurement cycles. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar step-down converter applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LT3692EMS8E-3.3#PBF | Higher 200mA output, wider 3.5V–42V input, but 25µA quiescent current - lacks programmable peak current limit. | Better suited for higher-current loads; less optimal for ultra-low-IQ battery systems where LTC3631EMS8E-3.3#PBF's 12µA provides >2× runtime advantage. | Select LT3692EMS8E-3.3#PBF only if load exceeds 100mA or input falls below 4.5V; otherwise LTC3631EMS8E-3.3#PBF offers superior IQ and feature set. |
| TPS62130ARGTR | 3.0V–17V input, 3A output, 17µA IQ, but no 45V rating or OVLO - requires external protection for industrial inputs. | Designed for low-voltage consumer electronics; unsuitable for direct replacement in 24V/48V industrial or automotive environments without added circuitry. | Use TPS62130ARGTR only in ≤17V systems with clean supplies; LTC3631EMS8E-3.3#PBF remains preferred for ruggedized 4.5V–45V applications demanding integrated surge protection. |
Compared with LT3692EMS8E-3.3#PBF and TPS62130ARGTR, the LTC3631EMS8E-3.3#PBF uniquely balances 45V input robustness, 12µA quiescent current, and programmable current limiting in a compact MSOP - making it the optimal choice for space-constrained, battery-sensitive industrial converters where reliability across voltage extremes is non-negotiable.
Availability
LTC3631EMS8E-3.3#PBF is available at Aetrix Electronics and suitable for industrial control supplies, 4–20mA current loops, and battery-operated devices requiring stable component supply, long-term lifecycle support, and guaranteed traceable sourcing.
Supply support for LTC3631EMS8E-3.3#PBF 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 product support, documentation, and manufacturing continuity for the LTC portfolio.
The LTC3631 series was designed specifically for high-input-voltage, low-quiescent-current step-down regulation in harsh industrial and instrumentation environments - emphasizing robustness, simplicity, and extended battery life.
FAQ
What is the output voltage tolerance of the LTC3631EMS8E-3.3#PBF over temperature?
The LTC3631EMS8E-3.3#PBF delivers a fixed 3.3V output with ±1.2% tolerance (3.26V to 3.36V) across the full –40°C to 125°C junction temperature range, as specified in the Electrical Characteristics table under "LTC3631-3.3V, VOUT Rising/Falling" conditions. This accuracy is maintained without external components due to its precision internal 0.800V feedback reference.
Does the LTC3631EMS8E-3.3#PBF require external compensation components?
No, the LTC3631EMS8E-3.3#PBF uses a proprietary hysteretic Burst Mode® control architecture that eliminates the need for external compensation networks. Its internal feedback loop is inherently stable across all operating conditions, reducing design complexity and PCB area versus traditional voltage-mode or current-mode controllers.
Can the LTC3631EMS8E-3.3#PBF operate with input voltages above 45V?
The LTC3631EMS8E-3.3#PBF has an absolute maximum VIN rating of 60V and includes internal overvoltage lockout (OVLO) that disables switching above ~47V to protect the device. While it can survive brief 60V transients, sustained operation above 45V violates the recommended operating conditions and may cause premature failure or regulation loss.
How is the peak inductor current programmed on the LTC3631EMS8E-3.3#PBF?
The LTC3631EMS8E-3.3#PBF sources a precise 1µA current from the ISET pin (Pin 3). Connecting a resistor RISET between ISET and GND generates a voltage offset that adjusts the peak current comparator threshold from 50mA (RISET = 0Ω) to 225mA (RISET open). The relationship is linear: RISET (kΩ) ≈ IPEAK (mA) × 4.5.
What thermal considerations apply to the MS8E package of the LTC3631EMS8E-3.3#PBF?
The LTC3631EMS8E-3.3#PBF in the MS8E package has θJA = 40°C/W and requires soldering of the exposed GND pad (Pin 9) to a PCB thermal plane. At 100mA output and 24V input, power dissipation is ~120mW; with 40°C/W, this yields ~4.8°C rise above ambient - confirming safe operation up to +85°C ambient without airflow or heatsinking.
LTC3631EMS8E-3.3#PBF Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- -
- Package/Case:
- 8-TSSOP, 8-MSOP (0.118", 3.00mm Width) Exposed Pad
- Packaging:
- Tube
- 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-MSOP-EP
LTC3631EMS8E-3.3#PBF FAQ
1.How can I place an order for LTC3631EMS8E-3.3#PBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LTC3631EMS8E-3.3#PBF 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 LTC3631EMS8E-3.3#PBF reliable?
The price and inventory of LTC3631EMS8E-3.3#PBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LTC3631EMS8E-3.3#PBF is usually 5 days.
3.What payment methods are accepted for LTC3631EMS8E-3.3#PBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LTC3631EMS8E-3.3#PBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LTC3631EMS8E-3.3#PBF?
LTC3631EMS8E-3.3#PBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LTC3631EMS8E-3.3#PBF 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 LTC3631EMS8E-3.3#PBF?
For technical support, including LTC3631EMS8E-3.3#PBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LTC3631EMS8E-3.3#PBF requirements.
6.How does Aetrix verify that LTC3631EMS8E-3.3#PBF is sourced from the original manufacturer or authorized distributors?
All LTC3631EMS8E-3.3#PBF 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 LTC3631EMS8E-3.3#PBF meets industry standards.
7.What is the process for return or replacement of LTC3631EMS8E-3.3#PBF?
All LTC3631EMS8E-3.3#PBF units undergo pre-shipment inspection (PSI). If there is an issue with LTC3631EMS8E-3.3#PBF, 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 LTC3631EMS8E-3.3#PBF part is unused and in its original packaging.
Return procedure for LTC3631EMS8E-3.3#PBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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