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Analog Devices Inc. LT8645SEV-2#PBF
- Part No.:
- LT8645SEV-2#PBF
- Manufacturer:
- Analog Devices Inc.
- Package:
- 32-TFQFN Exposed Pad
- Datasheet:
-
LT8645SEV-2#PBF.pdf
- Description:
- IC REG BUCK ADJ 8A 32LQFN
- Quantity:
- Payment:
- Shipping:
Inventory:3,117
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Product details
Overview
LT8645SEV-2#PBF from Analog Devices is a 65V, 8A synchronous step-down Silent Switcher regulator with 2.5µA quiescent current in Burst Mode, 40ns minimum on-time, and integrated power MOSFETs in a 32-lead 6mm × 4mm LQFN package. It delivers up to 95% efficiency at 1MHz (12VIN → 5VOUT) and supports spread spectrum modulation for ultra-low EMI in automotive and industrial power supplies.
For engineers reviewing the LT8645SEV-2#PBF datasheet, LT8645SEV-2#PBF pinout, LT8645SEV-2#PBF application, or LT8645SEV-2#PBF equivalent, key selection criteria include input voltage range (3.4V–65V), ultralow IQ regulation, AEC-Q100 qualification (E-grade), internal compensation, and programmable switching frequency (200kHz–2.2MHz).
Technical Context
The LT8645SEV-2#PBF implements peak current mode control with frequency foldback during start-up or overcurrent, enabling stable low-dropout operation (60mV @ 1A). Its Silent Switcher architecture uses symmetrical layout and integrated bypass capacitors to suppress common-mode EMI without external filters.
It features three selectable operating modes via SYNC/MODE pin: Burst Mode (ultralow IQ), pulse-skipping (full-frequency down to light loads), and spread spectrum (±20% frequency dithering). Internal 0.97V reference and soft-start/tracking (TR/SS pin) support precise output sequencing and transient immunity.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 3.4V to 65V - supports wide-range industrial, automotive, and telecom inputs without pre-regulation. |
| Output Current | 8A continuous - enables single-chip 5V/8A or 3.3V/8A conversion with minimal external components. |
| Quiescent Current | 2.5µA @ 12VIN→3.3VOUT - extends battery life in always-on systems such as telematics and sensor nodes. |
| Switching Frequency | 200kHz to 2.2MHz (RT-programmable) - allows optimization of size (high-freq) vs. efficiency (low-freq) and EMI compliance. |
| Minimum On-Time | 40ns - enables high step-down ratios (e.g., 48V→3.3V) at 2MHz without pulse skipping. |
| Feedback Reference | 0.97V ±0.006V - tight tolerance ensures accurate output regulation across temperature and load. |
| EMI Performance | CISPR 25 Class 5 compliant with spread spectrum - eliminates need for external EMI filters in automotive designs. |
Pinout & Package
LT8645SEV-2#PBF is housed in a thermally enhanced 32-lead LQFN package (6mm × 4mm × 0.94mm) with exposed GND pads (Pins 33–38) requiring PCB soldering for optimal thermal performance. The package footprint matches standard 6mm × 4mm QFN layouts.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| VIN (Pins 4,5,6,21,22,23) | Main input power supply | Supplies internal circuitry and top-side switch; requires multiple local bypass caps (0.47µF ×2 + 4.7µF) for low-impedance path. |
| GND (Pins 8,9,10,17,18,19,33–38) | Power and signal ground reference | Multiple dedicated pins + exposed thermal pad reduce ground loop inductance and improve EMI/thermal performance. |
| BST (Pin 11) | Bootstrap gate drive supply | Connects to 0.1µF ceramic capacitor between BST and SW to enable high-side NMOS gate drive above VIN. |
| SW (Pins 12–16) | Switch node output | Drives external inductor; must be minimized in PCB area to reduce radiated EMI and switching losses. |
| EN/UV (Pin 25) | Enable and undervoltage lockout | Hysteretic threshold (1.01V rise / 0.965V fall) enables reliable startup and brownout protection. |
| RT (Pin 26) | Frequency programming resistor | Resistor to GND sets switching frequency from 200kHz (221kΩ) to 2.2MHz (18.2kΩ); enables precise EMI tuning. |
| FB (Pin 32) | Feedback voltage sense | Regulates to 0.97V reference; connects to resistor divider tap; requires 1–10pF phase lead cap to VOUT for stability. |
| SYNC/MODE (Pin 28) | Operating mode selection | Ground = Burst Mode; float = pulse-skipping; INTVCC = spread spectrum; external clock = synchronization. |
Key Features
| Feature | Design Value |
|---|---|
| Silent Switcher® Architecture | Integrated dual-input power path and symmetrical layout reduce radiated EMI by >30dB vs. conventional buck regulators. |
| Ultralow Quiescent Current | 2.5µA IQ in regulation enables >10-year battery life in always-on IoT sensors and automotive standby modules. |
| Internal Power MOSFETs | Top switch RDS(on) = 36mΩ, bottom switch RDS(on) = 25mΩ - eliminates external FETs and gate drivers, reducing BOM count and layout complexity. |
| Spread Spectrum Modulation | ±20% triangular dithering of switching frequency reduces peak EMI amplitude, easing CISPR 25 Class 5 certification. |
| AEC-Q100 Qualified (Grade E) | Rated for –40°C to +125°C junction temperature - validated for automotive infotainment, ADAS cameras, and body control modules. |
| Output Soft-Start & Tracking | TR/SS pin supports user-defined slew rate and voltage sequencing with internal 2µA current source and 200Ω pull-down. |
Applications
| Automotive Infotainment Power | Industrial PLC I/O Module |
|---|---|
|
Use Scenario: Powering 5V/3A display controller and audio codec in head unit with 9V–16V battery input and strict EMI limits. IC Role / Device Role / Timing Role: Primary DC/DC converter delivering regulated 5V rail with spread spectrum enabled to meet CISPR 25 Class 5. Use Value: Eliminates external EMI filter, reduces solution size by 40%, and maintains <10mVP-P ripple under dynamic load. |
Use Scenario: Generating isolated 3.3V/2A logic supply for digital I/O cards in 24V industrial control cabinet. IC Role / Device Role / Timing Role: High-efficiency, wide-input buck regulator supporting 18V–36V nominal input with 100% duty cycle capability. Use Value: Delivers 94% efficiency at full load while maintaining 2.5µA quiescent current during sleep states for energy monitoring. |
| GSM Base Station RF Power | Medical Portable Monitor |
|
Use Scenario: Providing clean 3.3V/5A bias for PA driver stages in LTE small cell radio with 28V input and stringent noise floor requirements. IC Role / Device Role / Timing Role: Low-noise, high-current buck converter operating in Burst Mode during idle periods to minimize conducted emissions. Use Value: Achieves <–65dBc harmonics at 2.6GHz and supports fast load transient response (<20µs) for burst transmission. |
Use Scenario: Supplying 5V/1.5A for microcontroller, OLED display, and analog front-end in battery-powered patient monitor. IC Role / Device Role / Timing Role: Primary power management IC with soft-start and tracking to coordinate multi-rail power-up sequence. Use Value: Extends Li-ion battery runtime by 35% vs. legacy controllers due to 2.5µA IQ and >90% efficiency at 10mA load. |
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 |
|---|---|---|---|
| LT8645SJV-2#PBF | Same electrical specs; rated for –40°C to +150°C junction temperature (J-grade) | Required for under-hood automotive applications exceeding 125°C ambient | Select when extended temperature operation is mandatory; otherwise LT8645SEV-2#PBF suffices for cabin electronics. |
| LT8646SEV-2#PBF | External compensation (VC pin exposed); identical pinout and specs except no internal compensation network | Needed for custom loop shaping, high-PSRR designs, or non-standard output capacitors | Choose only if design requires manual compensation tuning; LT8645SEV-2#PBF offers plug-and-play stability with internal compensation. |
Compared with LT8645SJV-2#PBF and LT8646SEV-2#PBF, the LT8645SEV-2#PBF provides optimal balance of ease-of-use (internal compensation), automotive qualification (AEC-Q100 E-grade), and thermal performance for cabin-level electronics - avoiding over-specification while ensuring robustness and rapid time-to-market.
Availability
LT8645SEV-2#PBF is available at Aetrix Electronics and suitable for automotive infotainment systems, industrial PLC power supplies, and medical portable monitors requiring stable component supply, long-term lifecycle support, and RoHS/WEEE compliance.
Supply support for LT8645SEV-2#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 automotive markets since 1965.
The LT8645S-2 product line delivers high-efficiency, low-EMI power conversion for noise-sensitive applications including automotive ADAS, industrial automation, and portable medical devices - emphasizing reliability, regulatory compliance, and design simplicity.
FAQ
What is the maximum input voltage rating for LT8645SEV-2#PBF?
The LT8645SEV-2#PBF has an absolute maximum input voltage rating of 65V on the VIN pins. Operation is guaranteed across the full 3.4V to 65V input range, making it suitable for 48V industrial buses, automotive cold-crank (up to 60V), and telecom backup supplies. Exceeding 65V risks permanent damage per Absolute Maximum Ratings.
Does LT8645SEV-2#PBF require external compensation components?
No, the LT8645SEV-2#PBF features internal compensation and is optimized for use with standard ceramic output capacitors (e.g., 100µF X7R). Unlike the LT8646S variant, it does not expose the VC pin and requires no external compensation network - simplifying layout and reducing BOM count while maintaining stability across all operating conditions.
How is spread spectrum modulation enabled on LT8645SEV-2#PBF?
Spread spectrum modulation on the LT8645SEV-2#PBF is activated by connecting the SYNC/MODE pin (Pin 28) to INTVCC (~3.4V) or an external 3V–4V supply. This configures the device into pulse-skipping mode with ±20% triangular frequency dithering - reducing peak EMI amplitudes without affecting average switching frequency or efficiency.
What thermal performance can be expected from LT8645SEV-2#PBF in a typical layout?
In a standard 4-layer PCB with 2oz copper, 6 thermal vias under the exposed pad, and recommended layout (per DC2468A demo board), the LT8645SEV-2#PBF achieves θJA ≈ 17°C/W. At 8A load and 12V input, case temperature rise is ~45°C above ambient - well within the –40°C to +125°C operating junction range when airflow or heatsinking is applied.
Is LT8645SEV-2#PBF qualified for automotive applications?
Yes, the LT8645SEV-2#PBF is AEC-Q100 qualified (Grade E) for operation from –40°C to +125°C junction temperature and is approved for automotive cabin applications including infotainment, telematics, and ADAS camera modules. It meets stringent reliability, EMI, and qualification testing requirements defined in the AEC-Q100 standard.
LT8645SEV-2#PBF Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- Silent Switcher®2
- Package/Case:
- 32-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):
- 3.4V
- Voltage - Input (Max):
- 65V
- Voltage - Output (Min/Fixed):
- 0.97V
- Voltage - Output (Max):
- 65V
- Current - Output:
- 8A
- Frequency - Switching:
- 200kHz ~ 2.2MHz
- Synchronous Rectifier:
- Yes
- Operating Temperature:
- -40°C ~ 125°C (TJ)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 32-LQFN (6x4)
LT8645SEV-2#PBF FAQ
1.How can I place an order for LT8645SEV-2#PBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LT8645SEV-2#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 LT8645SEV-2#PBF reliable?
The price and inventory of LT8645SEV-2#PBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LT8645SEV-2#PBF is usually 5 days.
3.What payment methods are accepted for LT8645SEV-2#PBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LT8645SEV-2#PBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LT8645SEV-2#PBF?
LT8645SEV-2#PBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LT8645SEV-2#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 LT8645SEV-2#PBF?
For technical support, including LT8645SEV-2#PBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LT8645SEV-2#PBF requirements.
6.How does Aetrix verify that LT8645SEV-2#PBF is sourced from the original manufacturer or authorized distributors?
All LT8645SEV-2#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 LT8645SEV-2#PBF meets industry standards.
7.What is the process for return or replacement of LT8645SEV-2#PBF?
All LT8645SEV-2#PBF units undergo pre-shipment inspection (PSI). If there is an issue with LT8645SEV-2#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 LT8645SEV-2#PBF part is unused and in its original packaging.
Return procedure for LT8645SEV-2#PBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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