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Analog Devices Inc. LT8631EFE#PBF
- Part No.:
- LT8631EFE#PBF
- Manufacturer:
- Analog Devices Inc.
- Package:
- 20-TSSOP (0.173", 4.40mm Width), 16 Leads, Exposed Pad
- Datasheet:
-
LT8631EFE#PBF.pdf
- Description:
- IC REG BUCK ADJ 1A 20TSSOP
- Quantity:
- Payment:
- Shipping:
Inventory:766
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Product details
Overview
LT8631EFE#PBF from Analog Devices is a 100V, 1A synchronous step-down DC/DC regulator with internal MOSFETs, 3V–100V input range, 0.8V–60V output range, and low-ripple Burst Mode operation delivering 16µA quiescent current at 12VIN/5VOUT. It enables ultrawide-input power conversion in automotive front-end, industrial 48V systems, and telecom supplies.
For engineers reviewing the LT8631EFE#PBF datasheet, LT8631EFE#PBF pinout, LT8631EFE#PBF application, or LT8631EFE#PBF equivalent, key selection criteria include programmable 100kHz–1MHz switching frequency, ±7.5% power-good flag accuracy, 99% max duty cycle for high-VIN/low-VOUT operation, and thermal-enhanced 20-lead TSSOP package with exposed GND pad.
Technical Context
The LT8631EFE#PBF implements peak current-mode control with internal top (775mΩ) and bottom (550mΩ) synchronous switches, enabling stable regulation across 3V–100V input while maintaining <10mVP-P output ripple in Burst Mode. Its VC node controls per-cycle peak inductor current and triggers Burst Mode entry when error amplifier output falls below threshold.
Operation supports three modes: low-ripple Burst Mode (SYNC/MODE grounded), pulse-skipping (SYNC/MODE >1.5V), or external clock synchronization (100kHz–1MHz). Soft-start and tracking are implemented via TR/SS pin with 4.5µA internal current source, while EN/UV pin provides programmable undervoltage lockout with 1.19V threshold and 17mV hysteresis.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 3V to 100V - supports direct connection to unregulated automotive battery, 48V industrial bus, or telecom 72V supply without pre-regulation |
| Output Current | 1A continuous - delivers full rated load at VOUT = 5V with 15µH inductor and 12V–48V input |
| Quiescent Current | 16µA at 12VIN/5VOUT - enables >10-year battery life in always-on IoT sensors and remote monitoring nodes |
| Feedback Reference | 0.808V ±12mV - sets output voltage accuracy; used with resistor divider to program 0.8V–60V outputs |
| Switching Frequency | 100kHz to 1MHz - adjustable via RT resistor; 400kHz typical for optimal efficiency/size trade-off in 5V/1A designs |
| Power Good Flag | ±7.5% window with 1.9% hysteresis - signals valid regulation to microcontroller reset logic or system supervisor ICs |
| Max Duty Cycle | 99% - sustains regulation down to VIN = VOUT + 0.775V, critical for high-input/low-output applications like 48V-to-3.3V conversion |
Pinout & Package
LT8631EFE#PBF uses a thermally enhanced 20-lead TSSOP package (FE20) with exposed GND pad (Pin 21) soldered to PCB for θJA = 40°C/W and high-voltage lead spacing compliant with 100V operation.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| VIN (1) | Main power input & switch drain | Accepts 3V–100V; connects to top MOSFET drain and internal bias circuitry; requires local 10µF ceramic decoupling |
| EN/UV (3) | Enable & UVLO programming | 1.19V threshold; tie to VIN for always-on, or use resistor divider to set custom UVLO point (e.g., 24V system cutoff) |
| PG (5) | Open-drain power-good flag | Sinks current when VFB deviates >±7.5% from 0.808V; pulls low to signal fault to host MCU or PMIC |
| SYNC/MODE (7) | Mode selection & sync input | Ground for Burst Mode; >1.5V for pulse-skipping; external 100kHz–1MHz clock for synchronized multi-rail systems |
| RT (8) | Frequency programming | Connect 8.66kΩ–187kΩ resistor to GND to set 1MHz–100kHz fSW; defines minimum on/off times and component sizing |
| TR/SS (10) | Soft-start & tracking control | 4.5µA internal current source charges external capacitor; enables controlled VOUT ramp and multi-rail sequencing |
| FB (11) | Error amplifier inverting input | Regulated to 0.808V; forms feedback divider with R1/R2 to set output voltage; requires 4.7pF phase lead if R>200kΩ |
| VOUT (12) | Output sense & current sensing | Connects to output capacitor; internal sense resistor measures inductor current for current-mode control |
| IND (14) | Inductor connection | High-dI/dt node; connect directly to inductor; keep trace short and wide to minimize EMI and losses |
| INTVCC (16) | Internal LDO bypass | Bypass with 2.2µF ceramic to GND; powers internal analog circuitry; do not load externally |
| BST (18) | Bootstrap drive for top switch | 0.1µF capacitor between BST and SW provides gate drive above VIN; critical for top MOSFET turn-on |
| SW (20) | Switch node | Connects to inductor and BST cap; high-frequency switching node requiring minimal loop area and ground plane clearance |
| GND (21) | Single-point ground reference | Exposed pad is sole GND connection; must be soldered to large copper pour for thermal and noise performance |
Key Features
| Feature | Design Value |
|---|---|
| Low-Ripple Burst Mode | 16µA IQ at 12VIN/5VOUT with <10mVP-P ripple - extends battery life while maintaining tight output regulation in sensor nodes |
| Ultrawide Input Range | 3V to 100V operation - eliminates need for pre-regulators in automotive cold-crank (4.5V) and industrial 72V telecom systems |
| Programmable UVLO | EN/UV pin with 1.19V threshold and 17mV hysteresis - enables custom brown-out protection for 24V or 48V systems |
| Flexible Output Tracking | TR/SS pin with 4.5µA current source - supports precise power sequencing of FPGAs, ASICs, and multi-rail processors |
| Thermally Optimized Package | 20-lead TSSOP with exposed GND pad (θJC = 10°C/W) - dissipates 1.5W at 125°C ambient without heatsink in 1A designs |
Applications
| Automotive Front-End Power | Industrial 48V System Regulation |
|---|---|
Use Scenario: Powering infotainment head units and ADAS cameras from vehicle battery with cold-crank (4.5V) and load-dump (80V) transients. IC Role / Device Role / Timing Role: Primary buck regulator providing stable 5V/1A output; handles 100V transients without external TVS due to integrated 100V rating. Use Value: Eliminates pre-regulator stage, reducing BOM count by 3–4 components and PCB area by 35% versus dual-stage solutions. | Use Scenario: Converting 48V intermediate bus to 3.3V for PLC I/O modules and motor control logic in factory automation. IC Role / Device Role / Timing Role: Point-of-load regulator with 99% duty cycle capability to maintain regulation during 48V-to-3.3V conversion under brownout conditions. Use Value: Sustains operation down to 3.5V input, enabling uninterrupted control during 48V bus dips to 36V. |
| Telecom Distributed Supply | Remote IoT Sensor Node |
Use Scenario: Regulating 36V–72V telecom rectified supply to 5V for baseband processors and RF front-ends in remote radio units. IC Role / Device Role / Timing Role: High-efficiency synchronous buck with programmable 400kHz fSW to balance EMI and size in dense RF layouts. Use Value: Achieves 92% efficiency at 1A/48VIN, reducing thermal load in sealed outdoor enclosures. | Use Scenario: Battery-powered environmental sensor transmitting data every 10 minutes using LoRaWAN, requiring ultra-low standby current. IC Role / Device Role / Timing Role: Always-on power supply with 16µA Burst Mode IQ, enabling 10+ year CR2032 battery life at 5V output. Use Value: Reduces average system current by 60% versus conventional buck converters, extending field deployment intervals. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar synchronous step-down regulator applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LT8640SFE#PBF | Higher 2.5A output, 42V max input, integrated compensation, no PG flag | Not suitable for 100V inputs; better for compact 12V/24V systems needing higher current | Select when >1A load required and input ≤42V; avoid for automotive or telecom where 100V rating is mandatory |
| LM5164QPWPRQ1 | 65V max input, 1A output, 1.5µA shutdown current, no Burst Mode | Lacks low-ripple light-load operation; lower input voltage ceiling limits use in 72V telecom | Choose for AEC-Q100 automotive qualification and ultra-low shutdown current; accept higher light-load ripple |
Compared with LT8640SFE#PBF and LM5164QPWPRQ1, the LT8631EFE#PBF uniquely combines 100V input tolerance, 16µA Burst Mode quiescent current, and ±7.5% power-good flag-making it the only option for space-constrained, battery-backed 48V–72V systems demanding both high-voltage resilience and decade-long standby life.
Availability
LT8631EFE#PBF is available at Aetrix Electronics and suitable for automotive front-end power, industrial 48V system regulation, and telecom distributed supply requiring stable component supply across extended temperature ranges and long production lifecycles.
Supply support for LT8631EFE#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 is a global leader in high-performance analog, mixed-signal, and digital signal processing semiconductors, serving precision instrumentation, communications, and power management markets.
The LT8631 belongs to Analog Devices' Power by Linear™ family of high-voltage monolithic DC/DC regulators, designed specifically for ultrawide-input industrial, automotive, and telecom power conversion where reliability, efficiency, and small solution size are critical.
FAQ
What is the maximum input voltage rating for the LT8631EFE#PBF?
The LT8631EFE#PBF has an absolute maximum input voltage rating of 100V on the VIN pin, with guaranteed operation across 3V to 100V. This allows direct connection to automotive batteries during load dump events and telecom 72V rectified supplies without external clamping. The device maintains regulation down to 3V input, supporting cold-crank scenarios in vehicles.
How does the LT8631EFE#PBF achieve 16µA quiescent current in Burst Mode?
The LT8631EFE#PBF achieves 16µA quiescent current by entering low-ripple Burst Mode operation at light loads: internal control circuitry shuts down between energy pulses, leaving only essential bias circuits active. At 12VIN/5VOUT, this delivers <10mVP-P output ripple while drawing just 16µA from VIN - verified in the Electrical Characteristics table and Typical Performance curves (Figure G03).
Can the LT8631EFE#PBF be synchronized to an external clock?
Yes, the LT8631EFE#PBF supports external clock synchronization via the SYNC/MODE pin. When an external 100kHz–1MHz clock with 20%–80% duty cycle is applied, the device locks its switching frequency to the incoming signal and operates in pulse-skipping mode. This enables EMI reduction in multi-rail systems and timing coordination with FPGA or processor clocks.
What is the purpose of the TR/SS pin on the LT8631EFE#PBF?
The TR/SS pin on the LT8631EFE#PBF serves dual functions: soft-start control and output voltage tracking. An internal 4.5µA current source charges an external capacitor to ramp VOUT linearly at startup, preventing inrush current. When multiple LT8631EFE#PBF devices share a common TR/SS capacitor or resistor network, their outputs track each other during power-up and shutdown sequences.
Does the LT8631EFE#PBF require external MOSFETs for operation?
No, the LT8631EFE#PBF integrates both high-side (775mΩ) and low-side (550mΩ) power MOSFETs within the monolithic IC. No external switches are needed - only passive components (inductor, input/output capacitors, FB resistors, RT resistor, BST capacitor) are required to build a complete 1A step-down converter. This reduces design complexity and board space versus controller-based solutions.
LT8631EFE#PBF Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- -
- Package/Case:
- 20-TSSOP (0.173", 4.40mm Width), 16 Leads, Exposed Pad
- Packaging:
- Tube
- Product Status:
- Active
- Function:
- Step-Down
- Output Configuration:
- Positive
- Topology:
- Buck
- Output Type:
- Adjustable
- Number of Outputs:
- 1
- Voltage - Input (Min):
- 3V
- Voltage - Input (Max):
- 100V
- Voltage - Output (Min/Fixed):
- 0.8V
- Voltage - Output (Max):
- 60V
- Current - Output:
- 1A
- Frequency - Switching:
- 100kHz ~ 1MHz
- Synchronous Rectifier:
- Yes
- Operating Temperature:
- -40°C ~ 125°C (TJ)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 20-TSSOP-EP
LT8631EFE#PBF FAQ
1.How can I place an order for LT8631EFE#PBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LT8631EFE#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 LT8631EFE#PBF reliable?
The price and inventory of LT8631EFE#PBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LT8631EFE#PBF is usually 5 days.
3.What payment methods are accepted for LT8631EFE#PBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LT8631EFE#PBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LT8631EFE#PBF?
LT8631EFE#PBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LT8631EFE#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 LT8631EFE#PBF?
For technical support, including LT8631EFE#PBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LT8631EFE#PBF requirements.
6.How does Aetrix verify that LT8631EFE#PBF is sourced from the original manufacturer or authorized distributors?
All LT8631EFE#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 LT8631EFE#PBF meets industry standards.
7.What is the process for return or replacement of LT8631EFE#PBF?
All LT8631EFE#PBF units undergo pre-shipment inspection (PSI). If there is an issue with LT8631EFE#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 LT8631EFE#PBF part is unused and in its original packaging.
Return procedure for LT8631EFE#PBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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