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Analog Devices Inc. LT8643SIV#PBF
- Part No.:
- LT8643SIV#PBF
- Manufacturer:
- Analog Devices Inc.
- Package:
- 24-TFQFN Exposed Pad
- Datasheet:
-
LT8643SIV#PBF.pdf
- Description:
- IC REG BUCK ADJ 6A 24LQFN
- Quantity:
- Payment:
- Shipping:
Inventory:1,640
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Product details
Overview
LT8643SIV#PBF from Analog Devices is a 42V, 6A synchronous step-down Silent Switcher 2 regulator with external compensation, 30ns minimum on-time, forced continuous or spread-spectrum operation, and 2.5µA quiescent current in Burst Mode-designed for automotive infotainment power rails requiring ultralow EMI and fast transient response.
For engineers reviewing the LT8643SIV#PBF datasheet, LT8643SIV#PBF pinout, LT8643SIV#PBF application, or LT8643SIV#PBF equivalent, key selection criteria include external VC-loop compensation capability, 24-lead LQFN thermal performance (θJC = 7°C/W), AEC-Q100 qualification, and compatibility with 200kHz–3MHz switching frequency programming via RT resistor.
Technical Context
The LT8643SIV#PBF implements peak current mode control with a dedicated VC error amplifier output for external loop compensation-enabling precise current sharing across parallel converters and optimized transient response at 2MHz+ switching frequencies. Its Silent Switcher 2 architecture integrates internal bypass capacitors on VIN, BST, and INTVCC to minimize high-di/dt loop area and suppress radiated EMI without external filters.
It supports four distinct operating modes via SYNC/MODE pin: Burst Mode (ground), forced continuous mode (floating), spread-spectrum modulation (3–4V), and external clock synchronization (AC-coupled). The VC pin provides direct access to the transconductance error amplifier (1.7mS gain, ±350µA sink/source), allowing RC network tuning of bandwidth and phase margin.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 3.4V to 42V - supports 12V/24V/36V automotive battery systems with cold-crank headroom. |
| Output Current | 6A continuous, 7A peak - sustains full load under 125°C junction temperature with proper PCB copper and thermal pad soldering. |
| Quiescent Current | 2.5µA in Burst Mode (12VIN→3.3VOUT) - enables >10-year battery backup in always-on vehicle modules. |
| Switching Frequency | 200kHz to 3MHz (RT-programmable) - allows optimization between inductor size (1µH @ 3MHz) and efficiency (95% @ 2MHz, 12VIN→5VOUT). |
| Minimum On-Time | 30ns - enables 12VIN→1VOUT conversion at 2MHz without pulse-skipping instability. |
| Feedback Reference | 0.970V ±0.006V - ensures ±1% output accuracy over –40°C to 125°C, critical for ADAS sensor bias rails. |
| EMI Performance | CISPR 25 Class 5 compliant (radiated) with spread spectrum - eliminates need for external EMI filters in infotainment head units. |
Pinout & Package
LT8643SIV#PBF uses a 24-lead 4mm × 4mm × 0.94mm LQFN package with exposed thermal pad (pins 25–28, GND). The package is RoHS-compliant, MSL Level 3, and identical in footprint to standard QFN-24.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| VC (22) | Error amplifier output | Direct access to transconductance node (1.7mS) for external RC compensation-enables stable current sharing and <50µs load-step recovery at 6A. |
| SYNC/MODE (20) | Operating mode selector | Configures Burst Mode (GND), FCM (open), spread spectrum (3–4V), or sync (AC-coupled clock)-no external logic required. |
| TR/SS (21) | Soft-start & tracking input | Controls VOUT ramp rate via capacitor; below 1.6V forces FB tracking-prevents inrush into downstream FPGAs or ADCs. |
| PG (23) | Power good open-drain | Asserts high when FB is within ±7.5% of 0.97V and no fault (UVLO, thermal, EN/UV low)-drives enable chains for sequenced power-up. |
| FB (24) | Feedback reference node | Regulated to 0.970V; connects to resistor divider from VOUT-supports precision 3.3V/5V/12V outputs with <±1% tolerance. |
| VIN (5,6,13,14) | Main power input | Four parallel pins reduce impedance and thermal rise; requires ≥2.2µF local ceramic bypass per group near GND pins. |
| GND (3,16,25–28) | Power & signal ground | Eight GND connections including 4-exposed-pad thermal anchors-must be soldered to inner-layer copper pour for θJA ≤24°C/W. |
Key Features
| Feature | Design Value |
|---|---|
| Silent Switcher 2 architecture | Integrated VIN/BST/INTVCC bypass capacitors eliminate layout-sensitive EMI hotspots-CISPR 25 Class 5 compliance achieved without ferrites or shields. |
| External VC compensation | Enables multi-phase current sharing and bandwidth tuning up to 500kHz-critical for fast transient response in radar power supplies. |
| 30ns minimum on-time | Supports high step-down ratios (e.g., 24V→1.8V @ 2MHz) without subharmonic oscillation-reduces need for complex multi-stage designs. |
| AEC-Q100 Grade I | Qualified for –40°C to +125°C operation with lifetime reliability data-meets automotive infotainment and ADAS module requirements. |
| Spread spectrum modulation | 22% frequency dithering reduces peak EMI by >10dB-eliminates costly board-level filtering in compact center-stack displays. |
Applications
| Automotive Infotainment | Radar Power Supply |
|---|---|
Use Scenario: 12V battery-powered head unit supplying 5V/3A to SoC, display, and audio codecs. IC Role / Device Role / Timing Role: Primary buck converter delivering regulated 5V rail with ultra-low EMI to prevent RF interference with AM/FM reception. Use Value: Silent Switcher 2 architecture meets CISPR 25 Class 5 limits without external filters, reducing BOM cost and PCB area by 30%. |
Use Scenario: 24V vehicle system powering 3.3V/2A mmWave radar sensor with strict <100mV ripple requirement. IC Role / Device Role / Timing Role: High-efficiency, low-noise step-down regulator with 30ns on-time enabling 24V→3.3V conversion at 2MHz for compact magnetics. Use Value: External VC compensation delivers <20µs 2A–4A transient recovery-maintains radar timing integrity during rapid acceleration events. |
| Industrial PLC I/O Module | ADAS Camera Power |
Use Scenario: DIN-rail mounted controller requiring 5V/4A for fieldbus interface and microcontroller with wide input range (9–36V DC). IC Role / Device Role / Timing Role: Input-flexible buck regulator with forced continuous mode ensuring stable 5V output across variable industrial supply voltages. Use Value: 42V max input withstands 36V transients; 2.5µA quiescent current extends backup battery life during brownout conditions. |
Use Scenario: Compact rear-view camera module powered from 12V battery with EMI-sensitive image sensor and ISP. IC Role / Device Role / Timing Role: Low-ripple, low-EMI power source for 1.2V/1.8V/3.3V rails feeding CMOS image sensor and video processor. Use Value: Output ripple <10mVP-P and spread spectrum mode prevent visible noise bands in captured video under electromagnetic interference. |
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 |
|---|---|---|---|
| LT8640SIV#PBF | Internal compensation, no VC pin; 1.7µA Burst Mode IQ vs 230µA for LT8643S | Lacks current sharing capability; simpler for single-rail, fixed-output designs | Select when external compensation is unnecessary and lowest quiescent current is prioritized. |
| MPQ4433AGL-AEC1-Z | 3.5A max output, 40V max input, no spread spectrum, non-AEC-Q100 qualified | Lower current rating; not validated for automotive temperature cycling or lifetime reliability | Consider only for non-automotive industrial use where EMI and AEC-Q100 are not required. |
Compared with LT8640SIV#PBF, LT8643SIV#PBF trades slightly higher light-load IQ for essential VC-loop flexibility in multi-rail or paralleled systems; versus MPQ4433AGL-AEC1-Z, it delivers higher current, superior EMI suppression, and certified automotive reliability-justifying its use in safety-critical ADAS subsystems.
Availability
LT8643SIV#PBF is available at Aetrix Electronics and suitable for automotive infotainment, radar power supplies, and industrial PLC I/O modules requiring stable component supply with AEC-Q100 assurance and long-term production continuity.
Supply support for LT8643SIV#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 automotive, industrial, communications, and healthcare markets since 1965.
The LT8643SIV#PBF belongs to the Silent Switcher 2 family-engineered specifically for noise-sensitive automotive and industrial power conversion where EMI compliance, thermal efficiency, and transient robustness are non-negotiable design constraints.
FAQ
What is the maximum output current capability of the LT8643SIV#PBF?
The LT8643SIV#PBF delivers 6A continuous output current and supports 7A peak current under thermally optimized PCB conditions (exposed pad fully soldered, ≥2 oz copper, 4-layer stackup). Derating applies above 85°C ambient; full 6A is guaranteed up to 125°C junction temperature per datasheet thermal limits.
How does the VC pin on the LT8643SIV#PBF differ from the LT8640SIV#PBF?
The LT8643SIV#PBF features a dedicated VC pin (Pin 22) that exposes the error amplifier output for external RC compensation-enabling precise loop tuning, current sharing, and fast transient response. The LT8640SIV#PBF lacks this pin and uses internal compensation only, limiting flexibility in dynamic load applications.
Can the LT8643SIV#PBF operate with a 24V input and 3.3V output at 2MHz switching frequency?
Yes, the LT8643SIV#PBF supports 24V→3.3V conversion at 2MHz using an appropriate inductor (e.g., 1µH, 8A saturation current) and output capacitor (≥100µF low-ESR). Its 30ns minimum on-time prevents pulse-skipping, and external VC compensation maintains stability under this high step-down ratio.
Is the LT8643SIV#PBF qualified for automotive applications?
Yes, the LT8643SIV#PBF is AEC-Q100 Grade I qualified (–40°C to +125°C) and manufactured under automotive-specific process controls. It includes automotive reliability reports, enhanced ESD protection, and lifetime validation-making it suitable for infotainment, body electronics, and ADAS subsystems.
What is the purpose of the SYNC/MODE pin on the LT8643SIV#PBF?
The SYNC/MODE pin configures four operating modes: Burst Mode (GND), forced continuous mode (open), spread-spectrum modulation (3–4V), or external clock synchronization (AC-coupled). This single-pin interface eliminates external mode-select logic and simplifies design across varying EMI and transient response requirements.
LT8643SIV#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:
- 200kHz ~ 3MHz
- Synchronous Rectifier:
- Yes
- Operating Temperature:
- -40°C ~ 125°C (TJ)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 24-LQFN (4x4)
LT8643SIV#PBF FAQ
1.How can I place an order for LT8643SIV#PBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LT8643SIV#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 LT8643SIV#PBF reliable?
The price and inventory of LT8643SIV#PBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LT8643SIV#PBF is usually 5 days.
3.What payment methods are accepted for LT8643SIV#PBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LT8643SIV#PBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LT8643SIV#PBF?
LT8643SIV#PBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LT8643SIV#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 LT8643SIV#PBF?
For technical support, including LT8643SIV#PBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LT8643SIV#PBF requirements.
6.How does Aetrix verify that LT8643SIV#PBF is sourced from the original manufacturer or authorized distributors?
All LT8643SIV#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 LT8643SIV#PBF meets industry standards.
7.What is the process for return or replacement of LT8643SIV#PBF?
All LT8643SIV#PBF units undergo pre-shipment inspection (PSI). If there is an issue with LT8643SIV#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 LT8643SIV#PBF part is unused and in its original packaging.
Return procedure for LT8643SIV#PBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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