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Analog Devices Inc. LT8642SEV#PBF
- Part No.:
- LT8642SEV#PBF
- Manufacturer:
- Analog Devices Inc.
- Package:
- 24-TFQFN Exposed Pad
- Datasheet:
-
LT8642SEV#PBF.pdf
- Description:
- IC REG BUCK ADJ 10A 24LQFN
- Quantity:
- Payment:
- Shipping:
Inventory:1,189
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Product details
Overview
LT8642SEV#PBF from Analog Devices is a 18V, 10A synchronous step-down Silent Switcher 2 regulator featuring integrated bypass capacitors, 20ns minimum on-time, external VC compensation, and spread-spectrum EMI reduction. It delivers up to 96% efficiency at 1MHz (12VIN to 3.3VOUT) and operates across 2.8V–18V input in server power, automotive, and industrial DC/DC conversion.
For engineers reviewing the LT8642SEV#PBF datasheet, LT8642SEV#PBF pinout, LT8642SEV#PBF application, or LT8642SEV#PBF equivalent, key selection criteria include ultralow radiated EMI performance without external filters, forced continuous mode for fast transient response, and 4mm × 4mm LQFN thermal design with exposed GND pad soldering requirements.
Technical Context
The LT8642SEV#PBF implements peak current mode control with second-generation Silent Switcher 2 architecture, integrating internal VIN, BST, and INTVCC bypass capacitors to minimize high-di/dt loop area and eliminate layout sensitivity for CISPR 32 Class B compliance. Its 20ns minimum on-time enables 12V-to-1.2V conversion at 2MHz with minimal external components.
Operation modes are selected via SYNC/MODE pin: ground for Burst Mode (230µA IQ), floating for forced continuous mode (FCM), >3V for FCM + spread spectrum (±22% frequency modulation), or external clock for synchronization. External compensation at VC pin supports bandwidth optimization across 200kHz–3MHz switching frequencies.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 2.8V to 18V - supports wide-range industrial and automotive battery inputs without pre-regulation |
| Output Current | 10A continuous - sustains full load at 125°C junction temperature with proper PCB thermal design |
| Switching Frequency | 200kHz to 3MHz - programmable via RT resistor; 2MHz typical enables compact 0.28µH inductor |
| Min On-Time | 20ns - enables high step-down ratios (e.g., 12V→1.2V) at high frequencies without pulse-skipping |
| Feedback Reference | 0.597V ±3mV - tight tolerance ensures accurate output regulation across temperature and line |
| Quiescent Current | 230µA in Burst Mode - maintains <1mW standby power at light loads for always-on systems |
| EMI Performance | CISPR 32 Class B compliant - achieves pass without external EMI filter due to integrated capacitors and optimized layout |
Pinout & Package
LT8642SEV#PBF uses a 24-lead 4mm × 4mm LQFN package with exposed GND pads (pins 25–28). Thermal resistance θJA = 38°C/W (JEDEC board), reduced to 24°C/W on demo board with optimized copper and thermal vias. Exposed pads must be soldered to PCB ground plane for thermal and EMI performance.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| BIAS (1) | Internal regulator bias supply | Accepts ≥3.1V external supply (e.g., VOUT ≥3.3V) to reduce VIN current draw and improve efficiency |
| INTVCC (2) | Internal 3.4V regulator output | Must remain unconnected - powers internal logic; sourced from BIAS if active, else from VIN |
| VIN (4,5,6,13,14,15) | Main input power path | Multiple parallel pins reduce impedance; require local ≥4.7µF ceramic capacitor with low-ESL placement |
| BST (7) | Bootstrap capacitor node | Floats externally; internal 0.22µF capacitor supplies gate drive voltage for top MOSFET |
| SW (8–12) | Power switch output | Five paralleled pins connect to inductor; must be minimized in PCB area to suppress EMI radiation |
| EN/UV (17) | Enable and input UVLO control | Hysteresis of 40mV; rising threshold 0.99V allows precise input undervoltage shutdown |
| RT (18) | Oscillator frequency programming | Resistor to GND sets fSW: 221kΩ = 210kHz, 60.4kΩ = 700kHz, 18.2kΩ = 1.95MHz |
| SYNC/MODE (20) | Operating mode selection | GND = Burst Mode, float = FCM, >3V = FCM+spread spectrum, AC clock = sync |
| SS (21) | Soft-start and tracking control | 1.9µA internal pull-up charges external capacitor to program VOUT ramp rate |
| VC (22) | Error amplifier output | External RC network sets loop compensation; enables current sharing in parallel configurations |
| PG (23) | Power good open-drain flag | Asserts high when FB is within ±8% of 0.597V; pulled low during faults or EN/UV <1V |
| FB (24) | Feedback reference node | Regulated to 0.597V; requires 4.7–47pF phase-lead capacitor between FB and VOUT |
Key Features
| Feature | Design Value |
|---|---|
| Silent Switcher 2 Architecture | Integrated VIN/BST/INTVCC bypass capacitors minimize high-frequency current loop area, enabling CISPR 32 Class B pass without external EMI filter |
| Spread Spectrum Modulation | ±22% triangular frequency dither reduces peak EMI amplitude by spreading energy across 200kHz bandwidth, easing EMC certification |
| 20ns Minimum On-Time | Enables direct 12V-to-1.2V conversion at 2MHz, eliminating need for intermediate regulation stages and reducing BOM count |
| Forced Continuous Mode | Maintains fixed switching frequency across full load range, supporting fast load transients (<50µs recovery) and predictable EMI spectrum |
| External VC Compensation | Allows loop bandwidth tuning for optimal transient response with different inductors/frequencies; supports parallel regulator current sharing |
| CLKOUT Synchronization | Provides 200ns-wide clock pulses at fSW to align multiple regulators, reducing beat frequencies and system-level conducted EMI |
Applications
| Server Power Rails | Automotive ADAS Processors |
|---|---|
Use Scenario: Generating 1.2V/10A core supply for Xeon or AMD EPYC CPUs in 1U rack servers with strict airflow and thermal constraints. IC Role / Device Role / Timing Role: Primary point-of-load regulator delivering stable, low-noise power with <10mVP-P ripple and fast transient response to CPU DVFS events. Use Value: Silent Switcher 2 architecture eliminates need for bulky EMI filters, saving board space and cost while meeting FCC Class A emissions limits in dense server chassis. | Use Scenario: Powering vision SoCs (e.g., NVIDIA Orin) in camera modules requiring clean 1.8V/5A rails with minimal conducted noise coupling into analog sensor paths. IC Role / Device Role / Timing Role: High-efficiency buck converter operating in forced continuous mode to maintain constant switching frequency and avoid interference with image sensor clock domains. Use Value: Integrated bypass capacitors and spread spectrum reduce radiated emissions below CISPR 25 Level 5 limits, avoiding costly shielding or re-spin. |
| Industrial PLC I/O Modules | Medical Imaging FPGA Supplies |
Use Scenario: Providing isolated 3.3V/3A auxiliary rail in DIN-rail mounted PLCs with wide input (9–36V DC) and -40°C to +85°C ambient operation. IC Role / Device Role / Timing Role: Input-flexible buck regulator using EN/UV resistor divider for brownout protection and SS pin for controlled startup sequencing with other subsystems. Use Value: 2.8V–18V input range covers 12V/24V industrial buses; 125°C rated junction temperature ensures reliability in sealed enclosures without active cooling. | Use Scenario: Delivering ultra-low-noise 1.0V/8A supply to Xilinx Ultrascale+ FPGAs in portable ultrasound units where EMI must not interfere with RF front-end receivers. IC Role / Device Role / Timing Role: Low-ripple, high-PoL regulator operating in Burst Mode at standby and forced continuous during imaging acquisition bursts. Use Value: 240µA no-load quiescent current extends battery life; <10mVP-P output ripple prevents digital noise coupling into sensitive analog signal chains. |
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 |
|---|---|---|---|
| LT8645SIV#PBF | Same architecture, 12A rating, wider 3.4V–65V input range, larger 5mm × 6mm LQFN package | Supports higher input voltages (e.g., 48V industrial buses); requires larger PCB footprint and different thermal layout | Select when input exceeds 18V or output current >10A is needed; not drop-in due to package and pinout differences |
| MPQ4436AGL-AEC1-P | Automotive-grade 12A buck, 3.3V–36V input, no integrated bypass caps, requires external EMI filtering | Qualified per AEC-Q100 Grade 1; lacks Silent Switcher EMI advantages but offers extended temperature range (-40°C to +125°C) | Choose for automotive production where AEC-Q100 qualification is mandatory; expect higher layout sensitivity and added filter BOM cost |
Compared with LT8645SIV#PBF and MPQ4436AGL-AEC1-P, the LT8642SEV#PBF provides optimal EMI performance in space-constrained 4mm × 4mm layouts for 18V-input systems, while maintaining lower quiescent current than the MPQ4436 and smaller footprint than the LT8645S.
Availability
LT8642SEV#PBF is available at Aetrix Electronics and suitable for server power rails, automotive ADAS processors, and industrial PLC I/O modules requiring stable component supply with guaranteed long-term availability and traceable sourcing.
Supply support for LT8642SEV#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 industrial, automotive, communications, and healthcare markets.
The LT8642S product line delivers ultralow-EMI, high-efficiency DC/DC conversion for noise-sensitive applications including data center infrastructure, autonomous vehicle compute platforms, and medical imaging equipment.
FAQ
What is the maximum recommended junction temperature for continuous operation of the LT8642SEV#PBF?
The LT8642SEV#PBF is rated for continuous operation up to 125°C junction temperature. Its thermal design relies on soldering the exposed GND pads (25–28) to a robust PCB copper plane with thermal vias; θJA drops from 38°C/W (JEDEC board) to 24°C/W on optimized demo boards. Operation above 125°C triggers overtemperature protection, which reduces lifetime.
How does the LT8642SEV#PBF achieve CISPR 32 Class B compliance without external EMI filters?
The LT8642SEV#PBF integrates ceramic bypass capacitors for VIN, BST, and INTVCC directly into the LQFN package, minimizing high-di/dt loop areas. Combined with symmetrical SW pin layout, optimized internal routing, and optional spread spectrum modulation, it meets radiated emissions limits on standard 4-layer PCBs - as validated on DC2560A demo board with no external filter.
Can the LT8642SEV#PBF operate with an input voltage below 2.8V?
No. The absolute minimum input voltage for regulation is 2.5V (limiting condition), but the specified operational minimum is 2.8V per datasheet Electrical Characteristics. Below 2.8V, the internal regulators cannot sustain bias, causing UVLO shutdown or unstable operation. For sub-2.8V inputs, consider the LT8640S (1.8V–42V range) or LT8614 (3.4V–42V).
What is the purpose of the BIAS pin on the LT8642SEV#PBF, and how should it be connected?
The BIAS pin supplies current to internal circuitry when biased ≥3.1V, reducing VIN current draw and improving light-load efficiency. For VOUT ≥3.3V, connect BIAS directly to VOUT. For lower outputs or external supplies, use a 1µF local bypass capacitor. If unused, tie to GND - though this increases VIN quiescent current, especially at high fSW.
Does the LT8642SEV#PBF support output voltage tracking during power-up sequencing?
Yes. The SS pin enables precise output voltage tracking: applying a ramped voltage to SS forces the FB pin to regulate to VFB = 0.597V × (VSS/1V) until VSS exceeds 1V, after which the internal reference resumes control. An internal 1.9µA pull-up current allows simple RC soft-start; series resistance is required if driven by low-impedance sources to prevent damage during fault conditions.
LT8642SEV#PBF Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- Silent Switcher®1
- Package/Case:
- 24-TFQFN Exposed Pad
- Packaging:
- Tray
- Product Status:
- Active
- Function:
- Step-Down
- Output Configuration:
- Positive
- Topology:
- Buck
- Output Type:
- Adjustable
- Number of Outputs:
- 1
- Voltage - Input (Min):
- 2.8V
- Voltage - Input (Max):
- 18V
- Voltage - Output (Min/Fixed):
- 0.597V
- Voltage - Output (Max):
- 3.3V
- Current - Output:
- 10A
- Frequency - Switching:
- 200kHz ~ 3MHz
- Synchronous Rectifier:
- Yes
- Operating Temperature:
- -40°C ~ 125°C (TJ)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 24-LQFN (4x4)
LT8642SEV#PBF FAQ
1.How can I place an order for LT8642SEV#PBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LT8642SEV#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 LT8642SEV#PBF reliable?
The price and inventory of LT8642SEV#PBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LT8642SEV#PBF is usually 5 days.
3.What payment methods are accepted for LT8642SEV#PBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LT8642SEV#PBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LT8642SEV#PBF?
LT8642SEV#PBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LT8642SEV#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 LT8642SEV#PBF?
For technical support, including LT8642SEV#PBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LT8642SEV#PBF requirements.
6.How does Aetrix verify that LT8642SEV#PBF is sourced from the original manufacturer or authorized distributors?
All LT8642SEV#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 LT8642SEV#PBF meets industry standards.
7.What is the process for return or replacement of LT8642SEV#PBF?
All LT8642SEV#PBF units undergo pre-shipment inspection (PSI). If there is an issue with LT8642SEV#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 LT8642SEV#PBF part is unused and in its original packaging.
Return procedure for LT8642SEV#PBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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