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Analog Devices Inc. LT8643SEV-2#PBF
- Part No.:
- LT8643SEV-2#PBF
- Manufacturer:
- Analog Devices Inc.
- Package:
- 24-TFQFN Exposed Pad
- Datasheet:
-
LT8643SEV-2#PBF.pdf
- Description:
- IC REG BUCK ADJ 6A 24LQFN
- Quantity:
- Payment:
- Shipping:
Inventory:2,001
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Product details
Overview
LT8643SEV-2#PBF from Analog Devices is a 42V, 6A synchronous step-down Silent Switcher regulator with external compensation, 30ns minimum on-time, and 2.5µA quiescent current in Burst Mode operation. It delivers up to 95% efficiency at 2MHz (12VIN→5VOUT) and supports spread spectrum modulation for ultralow EMI in automotive power supplies.
For engineers reviewing the LT8643SEV-2#PBF datasheet, LT8643SEV-2#PBF pinout, LT8643SEV-2#PBF application, or LT8643SEV-2#PBF equivalent, key selection criteria include external VC-loop compensation for fast transient response, AEC-Q100 qualification, 200kHz–3MHz programmable switching frequency, and Silent Switcher architecture enabling CISPR 25 Class 5 compliance without shielding.
Technical Context
The LT8643SEV-2#PBF implements peak current mode control with an externally accessible error amplifier output (VC pin), enabling precise loop tuning for high-bandwidth load transients and multi-phase current sharing. Its Silent Switcher architecture uses symmetrical layout and integrated input capacitors to suppress common-mode EMI at source.
It supports four operating modes via SYNC/MODE pin: Burst Mode (ultralow IQ), Forced Continuous Mode (stable harmonics), Spread Spectrum (EMI reduction), and external synchronization (system clock alignment). Minimum on-time of 30ns enables 12VIN→1.2VOUT conversion at 2MHz.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 3.4V to 42V - supports wide automotive battery range including cold-crank (4.5V) and load-dump (40V) conditions. |
| Output Current | 6A continuous, 7A peak - sustains full load under thermal derating up to 125°C junction temperature. |
| Quiescent Current | 2.5µA in Burst Mode (12VIN→3.3VOUT) - enables >1-year battery life in always-on automotive modules. |
| Switching Frequency | 200kHz to 3MHz (RT-programmable) - allows optimization of size (high-freq) vs. efficiency (low-freq) and avoids AM band interference. |
| Feedback Reference | 0.970V ±6mV - enables accurate output regulation across temperature; supports resistive divider design for any VOUT ≥1V. |
| Min On-Time | 30ns - permits high step-down ratios (e.g., 24VIN→1.2VOUT) at 2MHz without pulse-skipping instability. |
| EMI Performance | CISPR 25 Class 5 compliant (radiated) with filter - eliminates need for metal shielding in infotainment and ADAS ECUs. |
Pinout & Package
LT8643SEV-2#PBF is housed in a thermally enhanced 24-lead LQFN package (4mm × 4mm × 0.94mm) with exposed GND pads (pins 25–28) soldered to PCB for θJC(PAD) = 7°C/W. The package matches standard QFN footprints and supports JEDEC-compliant reflow.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| BIAS (1) | External bias supply input | Reduces VIN current draw when tied to VOUT ≥3.3V; mandatory for <230µA sleep IQ in LT8643S-2 variant. |
| INTVCC (2) | Internal 3.4V regulator bypass | Requires ≥1µF low-ESR ceramic cap; powers gate drivers and control logic; sourced from BIAS if >3.1V, else from VIN. |
| GND (3,16,25–28) | Power and signal ground | Multiple GND pins + exposed pad minimize ground impedance and thermal resistance; pad must be soldered for rated performance. |
| VIN (5,6,13,14) | Main input power supply | Four parallel VIN pins reduce IR drop and enable robust 6A input path; requires dual 1µF + one ≥2.2µF local bypass caps. |
| BST (7) | Bootstrap capacitor connection | Drives high-side MOSFET gate above VIN; requires 0.1µF ceramic cap placed adjacent to pin. |
| SW (8–12) | Power switch node | Five paralleled SW pins reduce conduction loss and EMI; must connect directly to inductor with minimal trace area. |
| RT (18) | Frequency programming resistor | Resistor to GND sets fSW: 221kΩ = 210kHz, 60.4kΩ = 700kHz, 18.2kΩ = 1.95MHz - enables precise EMI band avoidance. |
| SYNC/MODE (20) | Operating mode selector | Ground = Burst Mode; open = FCM; INTVCC = spread spectrum; external clock = sync - no external components needed. |
| TR/SS (21) | Soft-start and tracking control | 1.9µA internal pull-up enables RC-programmed slew rate; <1.6V enables tracking; >1.6V enables regulation. |
| VC (22) | Error amplifier output | Direct access to compensation node; requires external RC network (e.g., 10kΩ + 1nF) for stability and current sharing. |
| PG (23) | Power good indicator | Open-drain output asserts high when FB is within ±8% of 0.97V and no fault (UVLO, thermal, EN); pulls low during startup/faults. |
| FB (24) | Feedback voltage sense | Regulates to 0.970V; connects to resistor divider midpoint; requires 4.7–22pF phase-lead cap to VOUT for stability. |
Key Features
| Feature | Design Value |
|---|---|
| External VC compensation | Enables custom loop bandwidth tuning and multi-phase current sharing for high-dynamic-load applications like radar power supplies. |
| Silent Switcher architecture | Integrated input capacitors and balanced layout reduce radiated EMI by >30dB vs. conventional buck regulators at 100MHz. |
| Spread spectrum modulation | 22% frequency dithering centered on programmed fSW reduces peak EMI amplitude by 10dB, easing CISPR 25 certification. |
| AEC-Q100 Grade E | Qualified for –40°C to +125°C operation with lifetime validation per automotive reliability standards (HTOL, TC, UHAST). |
| Ultralow dropout | 100mV dropout at 1A enables stable 3.3V output from 3.4V input - critical for start-stop engine operation. |
Applications
| Automotive Infotainment Power | ADAS Camera Module Supply |
|---|---|
Use Scenario: Powering SoC, DDR memory, and display interfaces in head units with strict EMI limits and cold-crank survival. IC Role / Device Role / Timing Role: Primary 5V/3.3V buck converter delivering clean, low-noise power with spread spectrum enabled to meet CISPR 25 Class 5. Use Value: Eliminates metal shielding and ferrite beads while maintaining <40dBµV/m radiated emissions at 150MHz–1GHz. | Use Scenario: Providing regulated 1.2V core and 2.8V I/O rails for CMOS image sensors in surround-view cameras. IC Role / Device Role / Timing Role: High-efficiency, low-ripple step-down regulator with 30ns min-on-time supporting 12VIN→1.2VOUT at 2MHz. Use Value: Enables compact 2-layer PCB design with 2.2µH inductor and 100µF output capacitance, reducing BOM cost by 35%. |
| Industrial PLC I/O Module | Electric Vehicle Battery Management |
Use Scenario: Generating isolated 5V/12V rails for analog front-ends and communication interfaces in harsh factory environments. IC Role / Device Role / Timing Role: Robust DC/DC converter with 42V max input and AEC-Q100 qualification ensuring operation during 40V load-dump transients. Use Value: Sustains regulation during 100ms 40V surges without latch-off or output droop, eliminating need for upstream TVS clamping. | Use Scenario: Powering microcontrollers and CAN transceivers in battery pack monitors exposed to wide temperature swings. IC Role / Device Role / Timing Role: Ultra-low-IQ buck regulator delivering 3.3V from 8–40V battery stack with 2.5µA shutdown current. Use Value: Extends shelf-life monitoring duration to >18 months on single CR2032 cell, meeting OEM long-term storage requirements. |
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 |
|---|---|---|---|
| LT8640SEV-2#PBF | Internal compensation; 1.7µA Burst Mode IQ (vs. 230µA); no VC pin; identical pinout and package. | Lacks external loop tuning; unsuitable for multi-phase or ultra-fast transient loads (e.g., LiDAR pulsed drivers). | Select when simplicity and lowest IQ are prioritized over dynamic performance and current sharing. |
| MPQ4433AGL-AEC1-P | 3.8V–60V input; 3.5A output; 2.5µA IQ; no spread spectrum; QFN-16 package; different pinout. | Lower current rating; no VC pin or Silent Switcher EMI suppression; requires external EMI filtering for automotive. | Select for cost-sensitive, lower-current applications where full 6A capability and Class 5 EMI compliance are not required. |
Compared with LT8640SEV-2#PBF, the LT8643SEV-2#PBF trades slightly higher light-load IQ for essential VC-loop flexibility and faster transient response; versus MPQ4433AGL-AEC1-P, it delivers superior EMI performance, higher current, and proven AEC-Q100 reliability in safety-critical domains.
Availability
LT8643SEV-2#PBF is available at Aetrix Electronics and suitable for automotive infotainment systems, ADAS camera modules, and industrial PLC I/O requiring stable component supply across extended temperature ranges and long production lifecycles.
Supply support for LT8643SEV-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 LT8643S-2 product line delivers high-efficiency, low-EMI power conversion for demanding automotive and industrial applications where reliability, small size, and regulatory compliance are non-negotiable.
FAQ
What is the maximum output current capability of the LT8643SEV-2#PBF under continuous operation?
The LT8643SEV-2#PBF delivers 6A continuous output current at ambient temperatures up to +85°C with proper PCB thermal design (exposed pad soldered, 2oz copper). At 125°C junction temperature, it sustains 6A with appropriate derating per thermal resistance curves in the datasheet. Peak current capability reaches 7A for short-duration pulses.
How does the LT8643SEV-2#PBF achieve ultralow EMI without external shielding?
The LT8643SEV-2#PBF achieves ultralow EMI through Analog Devices' Silent Switcher architecture: integrated input capacitors minimize high-di/dt loop area, and symmetrical internal power stage layout cancels magnetic fields. Combined with optional spread spectrum modulation, it meets CISPR 25 Class 5 radiated emissions limits on standard 4-layer PCBs without metal cans or ferrites.
Can the LT8643SEV-2#PBF operate from a 3.4V input and still regulate a 3.3V output?
Yes, the LT8643SEV-2#PBF supports true dropout operation: at 1A load, dropout voltage is 100mV, enabling stable 3.3V output from a 3.4V input. This is critical for automotive start-stop systems where battery voltage dips below 6V. The device maintains regulation down to 3.4V input across its full temperature range.
What is the function of the VC pin on the LT8643SEV-2#PBF and how is it used?
VC is the error amplifier output pin on the LT8643SEV-2#PBF, providing direct access to the control loop for external compensation. Unlike the LT8640S-2, the LT8643SEV-2#PBF requires an external RC network (e.g., 10kΩ resistor + 1nF capacitor to GND) from VC to ground to stabilize the loop, enable fast transient response, and support current sharing in multi-phase configurations.
Is the LT8643SEV-2#PBF qualified for automotive applications and what grade does it carry?
Yes, the LT8643SEV-2#PBF is AEC-Q100 qualified for automotive use. As indicated in the order information table, the "E" suffix denotes Grade E (–40°C to +125°C junction temperature), with full reliability testing including HTOL, temperature cycling, and unbiased HAST. It is approved for use in infotainment, ADAS, and body electronics systems.
LT8643SEV-2#PBF Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- Silent Switcher®2
- 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):
- 3.4V
- Voltage - Input (Max):
- 42V
- Voltage - Output (Min/Fixed):
- 0.97V
- Voltage - Output (Max):
- 42V
- Current - Output:
- 6A
- Frequency - Switching:
- 180kHz ~ 2.1MHz
- Synchronous Rectifier:
- Yes
- Operating Temperature:
- -40°C ~ 125°C
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 24-LQFN (4x4)
LT8643SEV-2#PBF FAQ
1.How can I place an order for LT8643SEV-2#PBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LT8643SEV-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 LT8643SEV-2#PBF reliable?
The price and inventory of LT8643SEV-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 LT8643SEV-2#PBF is usually 5 days.
3.What payment methods are accepted for LT8643SEV-2#PBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LT8643SEV-2#PBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LT8643SEV-2#PBF?
LT8643SEV-2#PBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LT8643SEV-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 LT8643SEV-2#PBF?
For technical support, including LT8643SEV-2#PBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LT8643SEV-2#PBF requirements.
6.How does Aetrix verify that LT8643SEV-2#PBF is sourced from the original manufacturer or authorized distributors?
All LT8643SEV-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 LT8643SEV-2#PBF meets industry standards.
7.What is the process for return or replacement of LT8643SEV-2#PBF?
All LT8643SEV-2#PBF units undergo pre-shipment inspection (PSI). If there is an issue with LT8643SEV-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 LT8643SEV-2#PBF part is unused and in its original packaging.
Return procedure for LT8643SEV-2#PBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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