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Analog Devices Inc. LTC3631IDD#PBF
- Part No.:
- LTC3631IDD#PBF
- Manufacturer:
- Analog Devices Inc.
- Package:
- 8-WFDFN Exposed Pad
- Datasheet:
-
LTC3631IDD#PBF.pdf
- Description:
- IC REG BUCK ADJ 100MA 8DFN
- Quantity:
- Payment:
- Shipping:
Inventory:173
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Product details
Overview
LTC3631IDD#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, operating from 4.5V to 45V input, and drawing only 12µA quiescent current in Burst Mode® operation. It features programmable peak current limit (50–225mA), 0.8V ±1% feedback reference, and internal soft-start - ideal for industrial control supplies and battery-operated devices requiring ultra-low standby power.
For engineers reviewing the LTC3631IDD#PBF datasheet, LTC3631IDD#PBF pinout, LTC3631IDD#PBF application, or LTC3631IDD#PBF equivalent, key selection criteria include its 45V max input rating, 12µA no-load IQ, DFN-8 (3mm × 3mm) thermal performance, and compatibility with fixed 3.3V/5V or adjustable output configurations using external resistive feedback.
Technical Context
The LTC3631IDD#PBF implements a hysteretic Burst Mode® control architecture with an internal 0.8V feedback comparator and 5mV hysteresis, enabling automatic transition between active switching and ultra-low-power sleep cycles. Its peak current limit is set via ISET pin biasing (1µA sourced), directly determining maximum inductor ramp current and average output capability.
Startup is managed by a precise RUN pin threshold (1.21V rising, 1.10V falling) with 110mV hysteresis, while HYST pin provides open-drain logic-level indication of RUN state. The device integrates both P-channel high-side and N-channel low-side power switches with typical RON of 3.0Ω and 1.5Ω respectively, eliminating external FETs and compensation networks.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 4.5V to 45V - supports wide industrial and automotive supply rails, including 24V and 36V systems. |
| Output Current | Up to 100mA - sufficient for powering microcontrollers, sensors, and interface ICs in distributed systems. |
| Quiescent Current | 12µA typical in regulation - enables multi-year battery life in always-on IoT and portable instrumentation. |
| Feedback Reference | 0.800V ±1% - enables accurate output regulation across temperature and line variations for fixed or adjustable designs. |
| Peak Current Limit | Programmable 50mA to 225mA via ISET resistor - allows optimization of inductor size, ripple, and efficiency at light loads. |
| Overvoltage Protection | 60V surge tolerance with internal OVLO - protects against load dump transients in automotive environments. |
| Package | 8-lead 3mm × 3mm DFN with exposed GND pad - delivers θJA = 43°C/W for reliable thermal management in compact layouts. |
Pinout & Package
Package: 8-lead (3mm × 3mm) plastic DFN with exposed thermal pad (Pin 9 = GND), rated for –40°C to 125°C junction temperature. Exposed pad must be soldered to PCB ground plane for optimal thermal and electrical performance.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| SW (Pin 1) | Switch node | Connects to inductor; carries high di/dt switching waveform - requires short, low-inductance layout to minimize EMI. |
| VIN (Pin 2) | Main input supply | Accepts 4.5V–45V; bypass capacitor required between VIN and GND for stability and noise suppression. |
| ISET (Pin 3) | Peak current programming | 1µA current source sets trip threshold; resistor to GND adjusts peak current from 50mA to 225mA. |
| SS (Pin 4) | Soft-start control | 5µA current source charges external capacitor; determines output voltage ramp time during startup. |
| RUN (Pin 5) | Enable/disable control | Active-high logic: >1.21V enables operation; <0.7V forces shutdown (3µA IQ). |
| VOUT/VFB (Pin 6) | Output feedback | For fixed-output versions, connect directly to VOUT; for adjustable, use resistive divider to 0.8V reference. |
| HYST (Pin 7) | Run hysteresis indicator | Open-drain output pulled low when RUN is inactive - used to augment RUN pin hysteresis externally. |
| GND (Pins 8 & 9) | Ground reference | Pins 8 and 9 are internally connected; Pin 9 is exposed thermal pad - must be soldered to PCB ground plane. |
Key Features
| Feature | Design Value |
|---|---|
| No external compensation required | Integrated hysteretic control eliminates need for loop compensation components - reduces BOM count and design iteration. |
| Low dropout operation | 100% duty cycle capability - maintains regulation even when VIN approaches VOUT, critical for brownout resilience. |
| Internal overvoltage lockout | Disables switching above 50V typical (47V min), protecting downstream circuitry from 60V surges without external clamping. |
| Adjustable soft-start | External capacitor on SS pin sets controlled output voltage ramp - prevents input supply droop during startup. |
| Precise RUN threshold with hysteresis | 1.21V enable / 1.10V disable with 110mV hysteresis - ensures clean, bounce-free power sequencing in noisy environments. |
Applications
| Industrial Control Supplies | 4–20mA Current Loops |
|---|---|
Use Scenario: Powering analog sensor transmitters and PLC I/O modules in factory automation systems with 24V DC rails. IC Role / Device Role / Timing Role: Primary DC/DC regulator converting unregulated 24V–36V field power to stable 3.3V or 5V for signal conditioning and ADC reference. Use Value: 12µA quiescent current minimizes self-heating in sealed enclosures; 45V input range accommodates long-cable voltage drop and transient spikes. | Use Scenario: Providing isolated, regulated supply for 4–20mA loop-powered transmitters in hazardous area instrumentation. IC Role / Device Role / Timing Role: Local point-of-load regulator generating clean 5V for op-amps and DACs driving the current loop. Use Value: Internal MOSFETs eliminate gate drivers; Burst Mode® maintains regulation down to µA-level loop currents without oscillation. |
| Portable Instruments | Battery-Operated Devices |
Use Scenario: Power management in handheld multimeters, gas detectors, and portable data loggers powered by two or three Li-ion cells. IC Role / Device Role / Timing Role: Efficient step-down converter supplying 3.3V to MCU and display backlight from variable 6V–12.6V battery stack. Use Value: 4.5V minimum input enables operation down to near-end-of-discharge; 12µA IQ extends battery runtime in sleep modes. | Use Scenario: Always-on subsystem power in smart sensors and wireless edge nodes using primary alkaline or lithium thionyl chloride batteries. IC Role / Device Role / Timing Role: Ultra-low-IQ buck regulator maintaining real-time clock, memory retention, and wake-up circuitry during deep sleep. Use Value: 3µA shutdown current and precise RUN threshold enable deterministic wake-up from external events without leakage-induced drain. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar step-down converter applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LT3692EMSE#PBF | Higher 200mA output, 3.5V–42V input, requires external compensation, larger MSOP-10 package. | Targets higher-current industrial sensors and motor drivers where 100mA is insufficient. | Select LT3692EMSE#PBF when >100mA load or tighter output voltage accuracy (<±0.5%) is required. |
| TPS62130ARGTR | 3V–17V input, 3A output, 17µA IQ, requires external compensation, 1.2MHz fixed-frequency PWM. | Suited for consumer-grade 5V USB-powered systems with moderate current demands and less stringent input voltage range. | Choose TPS62130ARGTR for cost-sensitive, medium-current applications where 45V input capability is unnecessary. |
Compared with LT3692EMSE#PBF and TPS62130ARGTR, the LTC3631IDD#PBF uniquely balances ultra-low quiescent current (12µA), 45V input tolerance, and integrated power switches in a thermally efficient 3mm × 3mm DFN - making it optimal for space-constrained, high-input-voltage, low-power industrial and battery systems where simplicity and reliability are prioritized over raw current capacity.
Availability
LTC3631IDD#PBF is available at Aetrix Electronics and suitable for industrial control supplies, 4–20mA current loops, and portable instrumentation requiring stable component supply, long-term lifecycle support, and guaranteed traceable sourcing.
Supply support for LTC3631IDD#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.
The LTC3631 belongs to Linear's high-voltage monolithic DC/DC converter product line, designed specifically for robust, low-quiescent-current regulation in harsh industrial, automotive, and battery-powered environments where input transients and extended temperature operation are critical.
FAQ
What is the maximum input voltage the LTC3631IDD#PBF can withstand without damage?
The LTC3631IDD#PBF has an absolute maximum VIN rating of 60V and includes internal overvoltage lockout (OVLO) that disables switching above 50V typical. This allows the device to survive automotive load-dump transients and industrial power-rail surges while maintaining safe operation within its 4.5V–45V functional input range. Sustained operation above 45V is not recommended for regulation integrity.
Does the LTC3631IDD#PBF require external compensation components?
No, the LTC3631IDD#PBF uses a proprietary hysteretic Burst Mode® control architecture that eliminates the need for external compensation components such as type-II or type-III error amplifier networks. Its internal feedback comparator and peak current sensing provide inherent stability across all load and input conditions - reducing bill-of-materials count and simplifying layout.
How is the output voltage configured for the LTC3631IDD#PBF?
The LTC3631IDD#PBF is offered in fixed-output versions (e.g., LTC3631IDD-3.3#PBF, LTC3631IDD-5#PBF) and an adjustable version. For fixed outputs, VOUT/VFB (Pin 6) connects directly to the output rail. For adjustable operation, a resistive divider scales the output voltage to match the internal 0.800V ±1% reference at Pin 6 - enabling custom output voltages from ~0.8V to ≤VIN.
What thermal considerations apply to the LTC3631IDD#PBF in its DFN package?
The LTC3631IDD#PBF in the 3mm × 3mm DFN package has θJA = 43°C/W and requires the exposed GND pad (Pin 9) to be soldered to a minimum 100mm² copper pour on the PCB for effective heat dissipation. Junction temperature must remain ≤125°C; under worst-case 45V input and 100mA load, thermal design should verify TJ = TA + (PD × 43°C/W) stays within limits using measured power loss.
Can the LTC3631IDD#PBF operate in 100% duty cycle mode?
Yes, the LTC3631IDD#PBF supports 100% duty cycle operation, allowing continuous conduction when VIN drops close to VOUT - essential for maintaining regulation during brownout conditions in industrial and automotive systems. This capability is enabled by its synchronous architecture and absence of minimum off-time constraints found in many PWM controllers.
LTC3631IDD#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)
LTC3631IDD#PBF FAQ
1.How can I place an order for LTC3631IDD#PBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LTC3631IDD#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 LTC3631IDD#PBF reliable?
The price and inventory of LTC3631IDD#PBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LTC3631IDD#PBF is usually 5 days.
3.What payment methods are accepted for LTC3631IDD#PBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LTC3631IDD#PBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LTC3631IDD#PBF?
LTC3631IDD#PBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LTC3631IDD#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 LTC3631IDD#PBF?
For technical support, including LTC3631IDD#PBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LTC3631IDD#PBF requirements.
6.How does Aetrix verify that LTC3631IDD#PBF is sourced from the original manufacturer or authorized distributors?
All LTC3631IDD#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 LTC3631IDD#PBF meets industry standards.
7.What is the process for return or replacement of LTC3631IDD#PBF?
All LTC3631IDD#PBF units undergo pre-shipment inspection (PSI). If there is an issue with LTC3631IDD#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 LTC3631IDD#PBF part is unused and in its original packaging.
Return procedure for LTC3631IDD#PBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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