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Analog Devices Inc. LT8643SIV#WPBF
- Part No.:
- LT8643SIV#WPBF
- Manufacturer:
- Analog Devices Inc.
- Package:
- 24-TFQFN Exposed Pad
- Datasheet:
-
LT8643SIV#WPBF.pdf
- Description:
- IC REG BUCK ADJ 6A 24LQFN
- Quantity:
- Payment:
- Shipping:
Inventory:3,687
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Product details
Overview
LT8643SIV#WPBF from Analog Devices is a 42V, 6A synchronous step-down Silent Switcher 2 regulator with external compensation, 30ns minimum on-time, 2.5µA quiescent current in Burst Mode (VIN=12V→3.3V), and AEC-Q100 automotive qualification. It delivers up to 96% efficiency at 1MHz (12VIN→5VOUT) and operates from –40°C to 125°C junction temperature.
For engineers reviewing the LT8643SIV#WPBF datasheet, LT8643SIV#WPBF pinout, LT8643SIV#WPBF application, or LT8643SIV#WPBF equivalent, this page provides verified technical context, package-validated pin functions, EMI-optimized design meaning of Silent Switcher 2 architecture, and real-world transient response data for automotive power rail design.
Technical Context
The LT8643SIV#WPBF implements peak current mode control with a dedicated VC error amplifier output for external loop compensation-enabling precise current sharing across parallel converters and fast load transient response at 2MHz switching. Its second-generation Silent Switcher 2 architecture integrates internal bypass capacitors for VIN, BST, and INTVCC, minimizing high-di/dt loop area and reducing radiated EMI without requiring complex PCB layout mitigation.
It supports four operating modes via the SYNC/MODE pin: Burst Mode (ultralow IQ), Forced Continuous Mode (FCM), spread spectrum modulation (reducing EMI peaks), and external clock synchronization. Minimum on-time of 30ns enables high step-down ratios (e.g., 36VIN→3.3VOUT) at 2MHz, while integrated 7.5A top FET current limit and thermal shutdown ensure robust operation under overload.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 3.4V to 42V - supports wide automotive battery transients including cold-crank (4.5V) and load-dump (40V+). |
| Output Current | 6A continuous, 7A peak - sustains full-rated load across full temperature range with proper thermal design. |
| Quiescent Current | 2.5µA (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) per application. |
| Minimum On-Time | 30ns - enables direct 24VIN→3.3VOUT conversion at 2MHz without intermediate stages. |
| EMI Performance | CISPR 25 Class 5 compliant (radiated) with spread spectrum - eliminates need for external EMI filters in infotainment/ADAS systems. |
| Package | 24-lead 4mm × 4mm LQFN - exposes GND pads (25–28) for low-θJC thermal path (7°C/W) and EMI shielding. |
Pinout & Package
LT8643SIV#WPBF uses a 24-lead LQFN package (4mm × 4mm × 0.94mm) with exposed GND pads (25–28) soldered to PCB for thermal and EMI performance. Pin 22 is VC (error amp output); pins 25–28 are GND and must be connected to system ground plane.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| VC (22) | Error amplifier output | Direct access to control loop node; RC network to GND sets bandwidth and phase margin for fast transient response. |
| SW (8–12) | Power switch node | Five paralleled SW pins reduce trace inductance and resistive loss; critical for low EMI and high-efficiency operation. |
| GND (3, 16, 22, 25–28) | Ground reference | Multiple GND connections minimize ground bounce; exposed pad (25–28) dominates thermal resistance (θJC = 7°C/W). |
| SYNC/MODE (20) | Operating mode selector | Configures Burst Mode (GND), FCM (float), spread spectrum (3–4V), or sync (external clock) - no external logic needed. |
| TR/SS (21) | Soft-start/tracking input | 1.9µA internal pull-up enables capacitor-based soft-start; below 1.6V enables output voltage tracking for sequencing. |
| PG (23) | Power good open-drain | Asserts after VFB reaches ±8% of 0.97V reference and remains valid only when VIN > 3.4V - reliable system power sequencing signal. |
Key Features
| Feature | Design Value |
|---|---|
| Silent Switcher 2 architecture | Integrated VIN/BST/INTVCC bypass capacitors eliminate layout-sensitive EMI hotspots and guarantee CISPR 25 Class 5 compliance. |
| External VC compensation | Enables precise current sharing in multiphase configurations and <20µs 2A→4A load transient recovery (fSW = 2MHz). |
| 30ns minimum on-time | Supports single-stage 36VIN→3.3VOUT conversion at 2MHz - reduces BOM count and board space vs. cascaded solutions. |
| AEC-Q100 Grade I | Qualified from –40°C to +125°C junction temperature with automotive reliability testing - suitable for engine bay and ADAS applications. |
| Burst Mode IQ = 2.5µA | Extends battery runtime in always-on vehicle networks (e.g., CAN wake-up receivers, telematics backup power). |
Applications
| Automotive Infotainment Power Supply | ADAS Camera Module Rail |
|---|---|
Use Scenario: Powering SoC, DDR memory, and display interfaces in head-unit systems with strict EMI limits. IC Role / Device Role / Timing Role: Primary 5V/3.3V buck converter delivering clean, low-noise rails with spread spectrum enabled. Use Value: Meets CISPR 25 Class 5 radiated emissions without external EMI filter, reducing BOM cost and board area by >30%. |
Use Scenario: Generating stable 1.8V/1.2V rails for image sensors and ISP processors in surround-view cameras. IC Role / Device Role / Timing Role: High-PIDR (power integrity during rapid load transients) regulator with 30ns min-on-time enabling direct 12VIN→1.2VOUT. Use Value: Achieves <100mV output deviation during 1A→3A load steps (20µs/div), eliminating need for large bulk capacitance. |
| Industrial PLC I/O Module | Electric Vehicle Battery Management System |
Use Scenario: Providing isolated 5V bias for analog front-ends and digital isolators in harsh factory environments. IC Role / Device Role / Timing Role: Input-filter tolerant buck supplying regulated 5V from 24VDC industrial bus with 42V surge immunity. Use Value: Sustains regulation down to 3.4V input and withstands 42V transients - eliminates need for upstream TVS or pre-regulator. |
Use Scenario: Powering MCU, CAN transceivers, and cell monitoring ICs in BMS slave boards exposed to battery pack voltage swings. IC Role / Device Role / Timing Role: AEC-Q100 qualified 6A buck converting pack voltage (8–42V) to 3.3V/5V system rails. Use Value: Automotive qualification ensures long-term reliability under thermal cycling and vibration; 2.5µA IQ extends sleep-mode battery life. |
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#WPBF | Internal compensation; 1.7µA Burst Mode IQ; no VC pin; identical pinout and package. | Lower complexity for single-rail designs; less suitable for current sharing or aggressive transient requirements. | Select when fast transient response is not required and layout simplicity is prioritized. |
| MPQ4433AGL-AEC1-Z | 3.5A max output; 40V max input; no spread spectrum; 17µA IQ; QFN-16 package. | Limited current capability and missing EMI features restrict use in high-power infotainment or ADAS. | Consider only for cost-sensitive, lower-current automotive subsystems where EMI filtering is acceptable. |
Compared with LT8640SIV#WPBF, the LT8643SIV#WPBF trades internal simplicity for external loop control and higher current, while MPQ4433AGL-AEC1-Z offers lower cost but sacrifices EMI performance, output current, and transient capability - making LT8643SIV#WPBF the optimal choice for demanding automotive power rails.
Availability
LT8643SIV#WPBF is available at Aetrix Electronics and suitable for automotive infotainment systems, ADAS camera modules, industrial PLC I/O, and EV battery management systems requiring stable component supply, AEC-Q100 compliance, and low EMI emissions.
Supply support for LT8643SIV#WPBF 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.
The LT8643SIV#WPBF belongs to the Silent Switcher 2 family, designed specifically for noise-sensitive automotive and industrial applications requiring ultra-low EMI, high efficiency at high frequencies, and robust operation across extreme temperature ranges.
FAQ
What is the maximum output current capability of the LT8643SIV#WPBF?
The LT8643SIV#WPBF delivers 6A continuous output current over its full operating temperature range (–40°C to 125°C junction), with 7A peak capability. This rating assumes proper PCB thermal design using the exposed GND pads (pins 25–28) and adequate copper area per Analog Devices' DC2530A demo board guidelines. Derating applies above 85°C ambient.
How does the LT8643SIV#WPBF achieve ultralow EMI without external filters?
The LT8643SIV#WPBF integrates ceramic bypass capacitors for VIN, BST, and INTVCC directly into the LQFN package, minimizing high-di/dt loop area. Combined with symmetrical internal layout and Silent Switcher 2 edge-rate control, this enables CISPR 25 Class 5 radiated emissions compliance on standard 2-layer PCBs - eliminating the need for ferrite beads or common-mode chokes in most automotive applications.
What is the function of the VC pin on the LT8643SIV#WPBF?
The VC pin (Pin 22) is the output of the internal error amplifier on the LT8643SIV#WPBF. It provides direct access to the control loop for external compensation via an RC network to GND. This enables precise tuning of bandwidth and phase margin, supporting fast transient response (<20µs for 2A→4A steps) and accurate current sharing in multiphase configurations.
Can the LT8643SIV#WPBF operate from a 3.4V input?
Yes, the LT8643SIV#WPBF has a minimum input voltage of 3.4V and maintains regulation down to this level. However, at inputs near 3.4V, the achievable output voltage is limited by dropout - e.g., at 1A load, dropout is ~100mV, so maximum VOUT ≈ 3.3V. For 3.3V output, VIN ≥ 3.5V is recommended to ensure margin.
Is the LT8643SIV#WPBF pin-compatible with the LT8640SIV#WPBF?
Yes, the LT8643SIV#WPBF is pin-compatible with the LT8640SIV#WPBF - both use the same 24-lead LQFN package and share identical pin assignments except that Pin 22 is VC on LT8643SIV#WPBF and GND on LT8640SIV#WPBF. This allows drop-in replacement where external compensation is added, though layout review is recommended to confirm VC routing.
LT8643SIV#WPBF 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):
- 3V
- 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:
- Automotive
- Qualification:
- AEC-Q100
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 24-LQFN (4x4)
LT8643SIV#WPBF FAQ
1.How can I place an order for LT8643SIV#WPBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LT8643SIV#WPBF 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#WPBF reliable?
The price and inventory of LT8643SIV#WPBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LT8643SIV#WPBF is usually 5 days.
3.What payment methods are accepted for LT8643SIV#WPBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LT8643SIV#WPBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LT8643SIV#WPBF?
LT8643SIV#WPBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LT8643SIV#WPBF 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#WPBF?
For technical support, including LT8643SIV#WPBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LT8643SIV#WPBF requirements.
6.How does Aetrix verify that LT8643SIV#WPBF is sourced from the original manufacturer or authorized distributors?
All LT8643SIV#WPBF 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#WPBF meets industry standards.
7.What is the process for return or replacement of LT8643SIV#WPBF?
All LT8643SIV#WPBF units undergo pre-shipment inspection (PSI). If there is an issue with LT8643SIV#WPBF, 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#WPBF part is unused and in its original packaging.
Return procedure for LT8643SIV#WPBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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