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Analog Devices Inc. LTC3631EDD#PBF
- Part No.:
- LTC3631EDD#PBF
- Manufacturer:
- Analog Devices Inc.
- Package:
- 8-WFDFN Exposed Pad
- Datasheet:
-
LTC3631EDD#PBF.pdf
- Description:
- IC REG BUCK ADJ 100MA 8DFN
- Quantity:
- Payment:
- Shipping:
Inventory:18,456
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Product details
Overview
LTC3631EDD#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 features 12µA no-load quiescent current, 0.8V ±1% feedback reference, programmable peak current limit (50–225mA), and Burst Mode® operation for high light-load efficiency. It is used in industrial control supplies and battery-operated devices requiring robust input surge tolerance.
For engineers reviewing the LTC3631EDD#PBF datasheet, LTC3631EDD#PBF pinout, LTC3631EDD#PBF application, or LTC3631EDD#PBF equivalent, key selection criteria include its 45V max input rating with 60V surge protection, thermally enhanced 3mm × 3mm DFN package, internal soft-start and RUN threshold control, and compatibility with fixed 3.3V/5V or adjustable output configurations.
Technical Context
The LTC3631EDD#PBF implements a hysteretic Burst Mode® control architecture with an internal 0.8V feedback comparator and 5mV hysteresis, enabling automatic transition between active burst cycles and ultra-low-power sleep mode. Its peak current limit is set via external resistor on ISET pin, directly determining maximum inductor ramp current and average output capability.
It integrates complementary P-channel high-side and N-channel low-side power switches with typical RON of 3.0Ω and 1.5Ω, respectively, and includes dedicated pins for RUN enable control (1.21V rising threshold), HYST hysteresis adjustment, SS soft-start timing, and VOUT/VFB feedback-enabling precise startup sequencing and stable regulation across wide input and load ranges.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 4.5V to 45V - supports wide industrial and automotive supply rails; overvoltage lockout protects up to 60V transients. |
| Output Current | Up to 100mA - maximum continuous regulated load; limited by peak current setting and thermal design. |
| No-Load Quiescent Current | 12µA typical - enables multi-year battery life in always-on sensor nodes and portable instruments. |
| Feedback Reference Voltage | 0.800V ±1% - precision reference for accurate output regulation; used with external divider for adjustable versions. |
| Peak Current Limit Range | 50mA to 225mA - set by resistor from ISET to GND; determines inductor sizing, ripple, and efficiency trade-offs. |
| Package | 8-lead 3mm × 3mm DFN (DD) with exposed GND pad - optimized thermal resistance (θJA = 43°C/W) for compact high-voltage designs. |
| Operating Junction Temp | –40°C to 125°C - qualified for industrial and extended-temperature embedded applications. |
Pinout & Package
Package: 8-lead (3mm × 3mm) plastic DFN with exposed GND pad (Pin 9), requiring soldering to PCB ground plane for thermal and electrical performance.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| SW (Pin 1) | Switch node | Connection point for external inductor; ties to drains of internal high-side and low-side MOSFETs. |
| VIN (Pin 2) | Main input supply | Accepts 4.5V–45V input; requires local ceramic bypass capacitor to GND for stability and EMI suppression. |
| 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 controls output voltage ramp time (default 0.75ms if floating). |
| RUN (Pin 5) | Enable/disable control | Active-high logic input; >1.21V enables operation, <0.7V forces shutdown (3µA IQ); 110mV internal hysteresis. |
| VOUT/VFB (Pin 6) | Output feedback | Connects to output for fixed versions; for adjustable versions, connects to resistive divider referencing 0.8V. |
| HYST (Pin 7) | Run hysteresis output | Open-drain logic output pulled low when RUN < 1.2V; used to add external hysteresis to RUN threshold. |
| GND (Pin 8 & Pin 9) | Ground reference | Pins 8 and 9 (exposed pad) are internally connected and must be soldered to PCB ground for thermal management and noise immunity. |
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-constrained systems. |
| Programmable peak current limit | Enables optimization of inductor size, input/output capacitance, and efficiency for specific load profiles (50–225mA range). |
| Internal and external soft-start | Prevents input supply droop during startup; internal 0.75ms ramp or user-defined ramp via SS pin capacitor. |
| Overvoltage lockout (OVLO) | Disables switching above 47–52V (rising/falling), protecting internal circuitry from 60V surges without external components. |
Applications
| 4–20mA Current Loops | Industrial Control Supplies |
|---|---|
Use Scenario: Powering loop-powered field transmitters in process automation systems with 24V DC supply rails subject to line transients. IC Role / Device Role / Timing Role: Primary DC/DC regulator converting unregulated 24V–48V plant supply to stable 3.3V or 5V for sensor signal conditioning and HART modem ICs. Use Value: 60V surge tolerance and 45V max input ensure uninterrupted operation during brownouts and lightning-induced spikes on long cable runs. |
Use Scenario: Providing isolated auxiliary power for PLC I/O modules, motor drives, and safety controllers operating in harsh factory environments. IC Role / Device Role / Timing Role: High-efficiency, low-noise buck converter supplying clean 5V to microcontrollers, ADCs, and digital isolators in DIN-rail mounted equipment. Use Value: 12µA quiescent current extends backup battery runtime during AC mains failure; DFN package enables dense, convection-cooled layouts. |
| Distributed Power Systems | Battery-Operated Devices |
Use Scenario: Local point-of-load regulation in telecom and datacom chassis where intermediate bus voltages (e.g., 12V, 24V, 48V) feed multiple subsystems. IC Role / Device Role / Timing Role: Secondary buck stage delivering 3.3V/100mA to FPGA configuration memory, clock buffers, or interface PHYs with minimal external components. Use Value: No compensation required and only three external parts (inductor + two caps) reduce design cycle time and improve reliability vs. controller-based solutions. |
Use Scenario: Power management in handheld test equipment, portable medical monitors, and remote environmental sensors powered by Li-ion or alkaline batteries. IC Role / Device Role / Timing Role: Main system regulator stepping down battery voltage (e.g., 9V PP3 or 2S Li-ion) to 3.3V for MCU, display, and wireless SoC. Use Value: 100% duty-cycle low-dropout operation sustains regulation down to 3.6V input, maximizing usable battery capacity before shutdown. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar high-voltage synchronous buck converter applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LT8609SIS8E#PBF | Higher 42V input rating, 2A output, Silent Switcher® architecture; requires external compensation; 2.5µA IQ. | Targets higher-current, lower-noise applications (e.g., RF, audio); not drop-in due to different pinout and control scheme. | Select when >100mA output or stricter EMI requirements exist; verify PCB layout changes for Silent Switcher layout rules. |
| TPS54240DGQR | 40V input, 2.5A output, external MOSFETs; 147µA IQ; requires full compensation network and boot capacitor. | Suitable for cost-sensitive, higher-power industrial supplies; lacks integrated switches and low-IQ sleep mode. | Choose for scalability beyond 100mA or when thermal budget allows discrete FETs; expect longer design validation cycle. |
Compared with LT8609SIS8E#PBF and TPS54240DGQR, the LTC3631EDD#PBF offers the lowest quiescent current (12µA) and simplest implementation (no compensation, integrated switches) for sub-100mA, space-constrained, high-input-voltage applications - making it optimal for battery longevity and rapid prototyping where efficiency at microamp loads is critical.
Availability
LTC3631EDD#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 LTC3631EDD#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 LTC3631EDD#PBF belongs to Linear's high-voltage monolithic DC/DC converter product line, designed specifically for rugged, low-quiescent-current regulation in industrial and instrumentation applications where wide input range and reliability under transient stress are mandatory.
FAQ
What is the maximum input voltage the LTC3631EDD#PBF can withstand without damage?
The LTC3631EDD#PBF has an absolute maximum VIN rating of 60V and includes internal overvoltage lockout (OVLO) that disables switching above ~47–52V. This allows the device to survive short-duration 60V transients - such as load dump events in automotive or industrial settings - without external protection circuitry, while maintaining safe operation within its 4.5V–45V functional input range.
Can the LTC3631EDD#PBF be used in adjustable-output configurations?
Yes, the LTC3631EDD#PBF supports adjustable output voltages using an external resistive divider connected to the VOUT/VFB pin. The internal 0.800V ±1% reference is compared against the divided output voltage, enabling precise regulation of any output ≥0.8V. Fixed 3.3V and 5V variants (e.g., LTC3631EDD-3.3#PBF) are also available, but the base LTC3631EDD#PBF part itself is functionally identical and configurable via external feedback.
How does the ISET pin affect efficiency and component selection in the LTC3631EDD#PBF?
The ISET pin on the LTC3631EDD#PBF programs the peak inductor current from 50mA to 225mA via an external resistor. Lower peak current reduces required inductor size, input/output capacitance, and RMS current stress - improving efficiency at light loads and minimizing board area. However, peak current must exceed twice the maximum load current (e.g., >200mA for 100mA output) to maintain regulation; undersizing causes dropout or instability.
Does the LTC3631EDD#PBF require external compensation components?
No, the LTC3631EDD#PBF uses a proprietary hysteretic Burst Mode® control architecture with internal compensation. It operates stably with only three external components for fixed-output versions: an inductor, input capacitor, and output capacitor. No feedback compensation network, type-II/type-III compensators, or additional resistors/capacitors are needed - significantly simplifying design and reducing bill-of-materials cost.
What thermal considerations apply to the LTC3631EDD#PBF in its 3mm × 3mm DFN package?
The LTC3631EDD#PBF in the DD package has θJA = 43°C/W and requires the exposed GND pad (Pin 9) to be soldered to a minimum 100mm² PCB copper area for effective heat dissipation. At 100mA output and 24V input, power dissipation is ~150mW; with proper thermal land design, junction temperature rise remains <7°C above ambient - well within the –40°C to 125°C operating range without forced airflow.
LTC3631EDD#PBF Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- -
- Package/Case:
- 8-WFDFN 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-DFN (3x3)
LTC3631EDD#PBF FAQ
1.How can I place an order for LTC3631EDD#PBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LTC3631EDD#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 LTC3631EDD#PBF reliable?
The price and inventory of LTC3631EDD#PBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LTC3631EDD#PBF is usually 5 days.
3.What payment methods are accepted for LTC3631EDD#PBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LTC3631EDD#PBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LTC3631EDD#PBF?
LTC3631EDD#PBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LTC3631EDD#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 LTC3631EDD#PBF?
For technical support, including LTC3631EDD#PBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LTC3631EDD#PBF requirements.
6.How does Aetrix verify that LTC3631EDD#PBF is sourced from the original manufacturer or authorized distributors?
All LTC3631EDD#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 LTC3631EDD#PBF meets industry standards.
7.What is the process for return or replacement of LTC3631EDD#PBF?
All LTC3631EDD#PBF units undergo pre-shipment inspection (PSI). If there is an issue with LTC3631EDD#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 LTC3631EDD#PBF part is unused and in its original packaging.
Return procedure for LTC3631EDD#PBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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