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Analog Devices Inc. LTC3631IMS8E-3.3#PBF
- Part No.:
- LTC3631IMS8E-3.3#PBF
- Manufacturer:
- Analog Devices Inc.
- Package:
- 8-TSSOP, 8-MSOP (0.118", 3.00mm Width) Exposed Pad
- Datasheet:
-
LTC3631IMS8E-3.3#PBF.pdf
- Description:
- IC REG BUCK 3.3V 100MA 8MSOP
- Quantity:
- Payment:
- Shipping:
Inventory:774
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Product details
Overview
LTC3631IMS8E-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 at a fixed 3.3V, operating from 4.5V to 45V input, featuring 12µA quiescent current in Burst Mode® and internal overvoltage lockout up to 60V - ideal for industrial control supplies and battery-operated instrumentation.
For engineers reviewing the LTC3631IMS8E-3.3#PBF datasheet, LTC3631IMS8E-3.3#PBF pinout, LTC3631IMS8E-3.3#PBF application, or LTC3631IMS8E-3.3#PBF equivalent, key selection criteria include its 3.3V fixed output, MS8E package thermal performance (θJA = 40°C/W), programmable peak current limit (50–225mA), precise RUN pin threshold (1.21V rising), and no-compensation design requiring only three external components.
Technical Context
The LTC3631IMS8E-3.3#PBF implements a hysteretic Burst Mode® control architecture with an internal 0.800V ±1% feedback reference and 5mV comparator hysteresis, enabling ultra-low quiescent current operation while maintaining regulation across load currents from 100µA to 100mA. Its peak-current-limited switching uses internal P-channel high-side and N-channel low-side MOSFETs with 3.0Ω and 1.5Ω typical on-resistance, respectively.
Startup is controlled by a precision RUN pin comparator (1.21V rising / 1.10V falling threshold, 110mV hysteresis), supported by internal soft-start (0.75ms default) and adjustable external soft-start via SS pin (5µA sourced current). Input protection includes undervoltage lockout (3.75–4.50V) and overvoltage lockout (47–52V), allowing safe exposure to 60V transients.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 4.5V to 45V - supports wide industrial and automotive battery inputs, with 60V surge tolerance |
| Output Voltage | Fixed 3.3V ±1.2% - factory-trimmed for stable logic supply without external resistors |
| Max Output Current | 100mA - sufficient for microcontrollers, sensors, and interface ICs in space-constrained systems |
| Quiescent Current | 12µA typical in Burst Mode® - enables multi-year battery life in always-on monitoring devices |
| Feedback Reference | 0.800V ±1% - high-precision reference enabling accurate output regulation across temperature |
| Peak Current Limit | Programmable 50mA to 225mA via ISET pin - allows optimization of inductor size and efficiency for specific load profiles |
| Thermal Resistance | θJA = 40°C/W (MS8E) - enables 100mA operation at +85°C ambient with minimal PCB copper |
Pinout & Package
Package: 8-lead plastic MSOP (MS8E), 3mm × 3mm footprint, 0.75mm profile, with exposed pad (Pin 9) tied to GND for optimal thermal and electrical performance.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| SW (Pin 1) | Switch Node | Connection to 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) |
| 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; capacitor to GND extends startup ramp time beyond internal 0.75ms default |
| RUN (Pin 5) | Enable/Shutdown Control | Active-high logic: >1.21V enables operation; <0.7V disables with 3µA shutdown current |
| VOUT/VFB (Pin 6) | Output Feedback | Internally connected to 3.3V output; provides feedback path for regulation loop |
| HYST (Pin 7) | Run Hysteresis Output | Open-drain logic output pulled low when RUN < 1.2V - used to add external hysteresis to RUN divider |
| GND (Pin 8) | Ground Reference | Analog and power ground; exposed pad (Pin 9) must be soldered to PCB ground plane |
Key Features
| Feature | Design Value |
|---|---|
| Burst Mode® Operation | Maintains regulation at light loads with 12µA IQ, eliminating linear regulator inefficiency in battery-powered systems |
| No Compensation Required | Internal compensation enables stable operation with only input/output capacitors and inductor - reduces BOM count and design risk |
| Integrated Power Switches | Monolithic P-ch high-side and N-ch low-side MOSFETs eliminate external FETs and gate drivers, saving board area and cost |
| Precision RUN Threshold | 1.21V rising / 1.10V falling with 110mV hysteresis ensures clean, bounce-free enable/disable sequencing in noisy environments |
| Overvoltage Lockout | Disables switching above 47–52V and sustains 60V transients - protects downstream circuitry in 24V/36V industrial bus applications |
Applications
| 4–20mA Current Loop Transmitter | Industrial Sensor Node |
|---|---|
Use Scenario: Powering a loop-powered 4–20mA transmitter from a 24V industrial bus with strict current budget constraints. IC Role / Device Role / Timing Role: Primary 3.3V regulator supplying ADC, microcontroller, and DAC - operates in Burst Mode® to minimize loop current draw. Use Value: 12µA quiescent current ensures headroom within the 4mA minimum loop current, enabling full functionality without violating Hart protocol compliance. |
Use Scenario: Remote environmental sensor node powered by primary lithium battery with 10+ year lifetime requirement. IC Role / Device Role / Timing Role: Main system regulator delivering 3.3V to ultra-low-power MCU and digital sensor interface during periodic wake-up bursts. Use Value: 12µA sleep current and no-compensation design reduce system-level power management complexity and extend battery service life. |
| Distributed Power in PLC Backplane | Automotive Body Control Module |
Use Scenario: Local 3.3V rail generation on modular PLC I/O cards fed from a shared 24V backplane with voltage ripple and transient exposure. IC Role / Device Role / Timing Role: Point-of-load regulator providing noise-isolated 3.3V for FPGA configuration and communication peripherals. Use Value: 45V max input rating and 60V surge tolerance withstand backplane transients; MS8E package enables compact placement near load. |
Use Scenario: Secondary 3.3V supply in body control unit powered from vehicle battery (9–16V nominal, up to 45V load dump). IC Role / Device Role / Timing Role: Regulator for CAN transceiver, EEPROM, and wake-up controller - must survive cold-crank and load-dump events. Use Value: Integrated UVLO/OVLO and 100% duty-cycle capability ensure reliable start-up during cold-crank (down to 4.5V) and robust operation during load dump. |
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, 3.5–42V input, 2.5µA IQ, but requires external compensation and has different pinout | Supports higher current loads; not drop-in due to different FB/COMP pin assignment and soft-start behavior | Select when >100mA output or lower IQ is required; redesign PCB layout and compensation network required |
| TPS62130ARGTR | 3–17V input, 3A output, 17µA IQ, adjustable output, QFN-16 package - no integrated OVLO or wide VIN range | Targets high-current, low-VIN applications; lacks 45V rating and 60V surge protection | Choose for cost-sensitive, high-efficiency 3.3V rails from 5V/12V sources where industrial transients are absent |
Compared with LT3692EMS8E-3.3#PBF and TPS62130ARGTR, the LTC3631IMS8E-3.3#PBF uniquely combines 45V input rating, 60V surge tolerance, 12µA IQ, and fixed 3.3V output in an MS8E package - making it optimal for space-constrained, high-reliability industrial and automotive auxiliary rails where simplicity and ruggedness are prioritized over raw current capability.
Availability
LTC3631IMS8E-3.3#PBF is available at Aetrix Electronics and suitable for industrial control supplies, 4–20mA current loops, and battery-operated instrumentation requiring stable component supply across extended temperature ranges (–40°C to 125°C).
Supply support for LTC3631IMS8E-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, 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 LTC3631IMS8E-3.3#PBF belongs to Linear's high-voltage monolithic DC/DC converter product line, designed specifically for rugged, low-quiescent-current regulation in harsh environments where wide input range, surge immunity, and minimal external components are critical.
FAQ
What is the maximum input voltage the LTC3631IMS8E-3.3#PBF can safely withstand?
The LTC3631IMS8E-3.3#PBF features overvoltage lockout that disables switching above 47–52V, but its absolute maximum VIN rating is 60V. This means the device can safely sustain 60V transients without damage, provided switching remains disabled - a key feature for industrial 24V bus and automotive load-dump resilience. Continuous operation is limited to 4.5V–45V.
Does the LTC3631IMS8E-3.3#PBF require external compensation components?
No, the LTC3631IMS8E-3.3#PBF uses an internally compensated hysteretic control architecture and requires no external compensation components. Only three external parts - an inductor, input capacitor, and output capacitor - are needed for basic operation, significantly simplifying design and improving reliability compared to voltage-mode controllers.
How is the output voltage set on the LTC3631IMS8E-3.3#PBF?
The LTC3631IMS8E-3.3#PBF is a fixed-output variant with the 3.3V regulation point laser-trimmed at wafer test. Pin 6 (VOUT/VFB) is internally connected to the output, eliminating the need for an external resistor divider. This ensures ±1.2% accuracy over temperature and line, and removes potential errors from external component tolerances and layout parasitics.
What is the purpose of the HYST pin on the LTC3631IMS8E-3.3#PBF?
The HYST pin (Pin 7) is an open-drain output pulled low when the RUN pin voltage falls below 1.2V, signaling shutdown state. It enables external hysteresis enhancement for the RUN comparator - for example, by connecting HYST to the RUN divider node to widen the enable/disable voltage window and prevent oscillation during slow-rising input rails.
Can the LTC3631IMS8E-3.3#PBF operate at 100% duty cycle?
Yes, the LTC3631IMS8E-3.3#PBF supports 100% duty cycle operation, allowing regulation down to VIN – VDROP (where VDROP is determined by RDS(ON) and load current). This enables stable output during cold-crank conditions in automotive applications where input voltage may dip to 4.5V while maintaining 3.3V output.
LTC3631IMS8E-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
LTC3631IMS8E-3.3#PBF FAQ
1.How can I place an order for LTC3631IMS8E-3.3#PBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LTC3631IMS8E-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 LTC3631IMS8E-3.3#PBF reliable?
The price and inventory of LTC3631IMS8E-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 LTC3631IMS8E-3.3#PBF is usually 5 days.
3.What payment methods are accepted for LTC3631IMS8E-3.3#PBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LTC3631IMS8E-3.3#PBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LTC3631IMS8E-3.3#PBF?
LTC3631IMS8E-3.3#PBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LTC3631IMS8E-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 LTC3631IMS8E-3.3#PBF?
For technical support, including LTC3631IMS8E-3.3#PBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LTC3631IMS8E-3.3#PBF requirements.
6.How does Aetrix verify that LTC3631IMS8E-3.3#PBF is sourced from the original manufacturer or authorized distributors?
All LTC3631IMS8E-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 LTC3631IMS8E-3.3#PBF meets industry standards.
7.What is the process for return or replacement of LTC3631IMS8E-3.3#PBF?
All LTC3631IMS8E-3.3#PBF units undergo pre-shipment inspection (PSI). If there is an issue with LTC3631IMS8E-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 LTC3631IMS8E-3.3#PBF part is unused and in its original packaging.
Return procedure for LTC3631IMS8E-3.3#PBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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