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Analog Devices Inc. LTC3631EMS8E#PBF
- Part No.:
- LTC3631EMS8E#PBF
- Manufacturer:
- Analog Devices Inc.
- Package:
- 8-TSSOP, 8-MSOP (0.118", 3.00mm Width) Exposed Pad
- Datasheet:
-
LTC3631EMS8E#PBF.pdf
- Description:
- IC REG BUCK ADJ 100MA 8MSOP
- Quantity:
- Payment:
- Shipping:
Inventory:4,174
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Product details
Overview
LTC3631EMS8E#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 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 during 60V input surges. It is used in industrial control supplies and 4–20mA current loop transmitters where wide-input, low-quiescent power conversion is critical.
For engineers reviewing the LTC3631EMS8E#PBF datasheet, LTC3631EMS8E#PBF pinout, LTC3631EMS8E#PBF application, or LTC3631EMS8E#PBF equivalent, key selection considerations include its 4.5V–45V input range, internal synchronous switches, 0.8V ±1% feedback reference, MS8E package thermal performance (θJA = 40°C/W), and compatibility with fixed 5V output configuration per order code.
Technical Context
The LTC3631EMS8E#PBF implements a hysteretic Burst Mode® control architecture with an internal 0.8V feedback comparator and 5mV hysteresis, enabling ultra-low quiescent current operation by alternating between short burst cycles and deep-sleep intervals. Its peak current limit is set via external resistor on ISET pin, directly scaling maximum average output current (up to 112mA).
Startup is controlled by a precise RUN pin threshold (1.21V rising, 1.10V falling) with 110mV hysteresis, supported by HYST open-drain logic output for external hysteresis adjustment. Internal soft-start ramps output voltage over 0.75ms, while external capacitor on SS pin allows user-defined ramp time and inrush control.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 4.5V to 45V - supports direct connection to unregulated industrial rails, automotive batteries, and PoE-derived supplies without pre-regulation. |
| No-Load Quiescent Current | 12µA typical - enables multi-year battery life in always-on remote sensors and loop-powered field instruments. |
| Output Current Capability | 100mA continuous - sufficient to power microcontrollers, RS-485 transceivers, and analog front-ends in distributed control nodes. |
| Feedback Reference Voltage | 0.800V ±1% - enables accurate adjustable output regulation and stable 5V fixed-output operation using internal resistor divider. |
| Overvoltage Lockout Threshold | 47V rising / 45V falling - protects against 60V transient surges common in 24V/48V industrial systems without external clamping. |
| Peak Current Limit Range | 50mA to 225mA (programmable via ISET resistor) - allows optimization of inductor size, ripple, and efficiency for specific load profiles. |
| Package Thermal Resistance | θJA = 40°C/W (MS8E) - ensures reliable operation at full load in compact industrial PCB layouts without forced airflow. |
Pinout & Package
The LTC3631EMS8E#PBF is housed in an 8-lead plastic MSOP (MS8E) package with exposed pad (Pin 9), requiring soldering to PCB ground plane for optimal thermal and electrical performance. Pin pitch is 0.65mm; package dimensions are 3mm × 3mm × 1.1mm.
| 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 to minimize EMI. |
| VIN (Pin 2) | Main input supply | Accepts 4.5V–45V input; must be bypassed with low-ESR ceramic capacitor close to pin to suppress high-frequency ripple. |
| ISET (Pin 3) | Peak current programming input | Sources 1µA; resistor to GND sets peak inductor current from 50mA (shorted) to 225mA (open), directly controlling max output capability. |
| SS (Pin 4) | Soft-start control | Sources 5µA; external capacitor to GND extends startup ramp beyond internal 0.75ms, limiting inrush and preventing input droop. |
| RUN (Pin 5) | Enable/disable control | Logic-high >1.21V enables regulation; <0.7V forces shutdown (3µA IQ); hysteresis prevents chatter near threshold. |
| VOUT/VFB (Pin 6) | Output feedback | For fixed 5V version (LTC3631EMS8E#PBF), internally connected to output; serves as error amplifier input referenced to 0.8V. |
| HYST (Pin 7) | Run hysteresis logic output | Open-drain output pulled low when RUN <1.2V; usable to drive external pull-up for custom hysteresis or status indication. |
| GND (Pin 8 + Exposed Pad 9) | Power and signal ground | Exposes thermal pad (Pin 9) - mandatory soldering to large PCB ground plane required for thermal dissipation and noise immunity. |
Key Features
| Feature | Design Value |
|---|---|
| Burst Mode® operation | Maintains regulation at light loads while drawing only 12µA, eliminating need for external enable sequencing in battery-backed systems. |
| Integrated synchronous MOSFETs | Eliminates external high-side and low-side switches, reducing BOM count to just inductor, input/output capacitors, and optional ISET/SS resistors. |
| Programmable peak current limit | Enables precise matching of inductor saturation current and output capacitor ripple rating - avoids overdesign and saves board space. |
| Precise RUN pin threshold with hysteresis | Guarantees clean, chatter-free startup/shutdown across temperature (-40°C to 125°C), critical for reliability in harsh industrial environments. |
| Internal overvoltage lockout to 60V | Withstands ISO 7637-2 pulse 1/2a/5a transients without external TVS, simplifying design for automotive and factory automation applications. |
Applications
| 4–20mA Current Loop Transmitter | Industrial Sensor Node Power Supply |
|---|---|
Use Scenario: Powering precision DACs, op-amps, and HART modems in two-wire field transmitters powered from loop current. IC Role / Device Role / Timing Role: Primary regulated 5V supply derived from 12–42V loop voltage; provides stable bias for analog signal chain and digital communication. Use Value: 12µA quiescent current ensures loop compliance margin remains intact even at minimum 4mA loop current; 45V max input accommodates long-cable voltage drop. |
Use Scenario: Local power conversion for wireless sensor nodes deployed in PLC cabinets or motor control enclosures with noisy 24V DC rails. IC Role / Device Role / Timing Role: Point-of-load regulator converting unregulated 24V industrial bus to clean 5V for MCU, RF module, and ADC. Use Value: 60V surge tolerance eliminates need for upstream TVS; MS8E package fits dense control board layouts; Burst Mode extends battery life in hybrid-powered units. |
| Distributed Control System (DCS) I/O Module | Automotive Body Control Module (BCM) |
Use Scenario: Providing isolated 5V rail for analog input conditioning and digital isolation in modular DCS backplanes. IC Role / Device Role / Timing Role: Secondary regulator downstream of main 5V or 3.3V system rail, handling local transducer interface loads. Use Value: Low dropout (100% duty cycle) allows operation down to 4.5V input - essential during brownout conditions in aging plant infrastructure. |
Use Scenario: Powering LIN bus transceivers, LED drivers, and window/mirror control ICs in 12V automotive subsystems. IC Role / Device Role / Timing Role: Input-tolerant buck converter accepting battery voltage (9–16V nominal, up to 45V crank) and delivering stable 5V. Use Value: 45V operating range covers load-dump transients; 125°C junction rating supports under-hood placement; no external compensation reduces layout sensitivity. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar synchronous step-down converter applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LT3652IMSE#PBF | 4.95V–32V input, 2A output, constant-current/constant-voltage charge management; no programmable peak current limit. | Designed for Li-ion battery charging, not general-purpose regulation; lacks 45V surge tolerance and 12µA IQ. | Select only if battery charging functionality is required; not a functional substitute for LTC3631EMS8E#PBF in fixed 5V supply roles. |
| TPS54202DRCT | 4.5V–28V input, 2A output, 2.5MHz fixed-frequency PWM; 26µA IQ in Eco-mode, no Burst Mode. | Higher output current but narrower input range and higher quiescent current; less suitable for 48V industrial or battery-backed systems. | Prefer for high-frequency, high-current designs where EMI filtering is prioritized over ultra-low IQ; verify 28V max input suffices. |
Compared with LT3652IMSE#PBF and TPS54202DRCT, the LTC3631EMS8E#PBF uniquely combines 45V input tolerance, 12µA quiescent current, and programmable peak current in an MS8E package - making it optimal for space-constrained, wide-input, low-power industrial regulators where efficiency at microamp loads is non-negotiable.
Availability
LTC3631EMS8E#PBF is available at Aetrix Electronics and suitable for industrial control supplies, 4–20mA current loop transmitters, and distributed power systems requiring stable component supply across extended temperature ranges and long production lifecycles.
Supply support for LTC3631EMS8E#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 LTC3631 product line was designed specifically for high-input-voltage, low-quiescent-current DC/DC conversion in harsh environments - targeting applications like process instrumentation, factory automation, and automotive subsystems where reliability and wide VIN range are paramount.
FAQ
What is the guaranteed operating temperature range for the LTC3631EMS8E#PBF?
The LTC3631EMS8E#PBF is rated for –40°C to 125°C junction temperature. This extended range is validated across all electrical specifications and ensures reliable operation in industrial enclosures, under-hood automotive locations, and outdoor sensor housings without derating.
Does the LTC3631EMS8E#PBF require external compensation components?
No, the LTC3631EMS8E#PBF uses a hysteretic Burst Mode® control architecture that requires no external compensation. Its internal feedback loop is fully self-contained, eliminating the need for compensation capacitors or resistors - simplifying layout and improving stability across input/output variations.
How is the output voltage configured for the LTC3631EMS8E#PBF?
The LTC3631EMS8E#PBF is the fixed 5V output version. Its VOUT/VFB pin (Pin 6) connects internally to the output, eliminating the need for external feedback resistors. For adjustable outputs, other variants (e.g., LTC3631EDD#PBF) require an external resistor divider to set VOUT relative to the 0.8V reference.
What is the function of the HYST pin on the LTC3631EMS8E#PBF?
The HYST pin (Pin 7) is an open-drain logic output pulled low when the RUN pin voltage falls below 1.2V. It enables external hysteresis adjustment for the RUN comparator - for example, by connecting a resistor from HYST to RUN - allowing customized enable/disable thresholds in noisy supply environments.
Can the LTC3631EMS8E#PBF operate with 100% duty cycle?
Yes, the LTC3631EMS8E#PBF supports 100% duty cycle operation, enabling dropout-free regulation when VIN approaches VOUT (e.g., 5.5V input to 5V output). This feature is critical for maintaining output stability during brownout conditions in industrial power systems.
LTC3631EMS8E#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:
- 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-MSOP-EP
LTC3631EMS8E#PBF FAQ
1.How can I place an order for LTC3631EMS8E#PBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LTC3631EMS8E#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#PBF reliable?
The price and inventory of LTC3631EMS8E#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#PBF is usually 5 days.
3.What payment methods are accepted for LTC3631EMS8E#PBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LTC3631EMS8E#PBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LTC3631EMS8E#PBF?
LTC3631EMS8E#PBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LTC3631EMS8E#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#PBF?
For technical support, including LTC3631EMS8E#PBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LTC3631EMS8E#PBF requirements.
6.How does Aetrix verify that LTC3631EMS8E#PBF is sourced from the original manufacturer or authorized distributors?
All LTC3631EMS8E#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#PBF meets industry standards.
7.What is the process for return or replacement of LTC3631EMS8E#PBF?
All LTC3631EMS8E#PBF units undergo pre-shipment inspection (PSI). If there is an issue with LTC3631EMS8E#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#PBF part is unused and in its original packaging.
Return procedure for LTC3631EMS8E#PBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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