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Analog Devices Inc. LT8643SIV-2#PBF
- Part No.:
- LT8643SIV-2#PBF
- Manufacturer:
- Analog Devices Inc.
- Package:
- 24-TFQFN Exposed Pad
- Datasheet:
-
LT8643SIV-2#PBF.pdf
- Description:
- IC REG BUCK ADJ 6A 24LQFN
- Quantity:
- Payment:
- Shipping:
Inventory:907
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Product details
Overview
LT8643SIV-2#PBF from Analog Devices is a 42V, 6A synchronous step-down Silent Switcher regulator with external compensation, 2.5µA quiescent current in Burst Mode, 30ns minimum on-time, and AEC-Q100 qualification for automotive applications. It delivers up to 96% efficiency at 1MHz (12VIN→5VOUT) and supports spread-spectrum EMI reduction.
For engineers reviewing the LT8643SIV-2#PBF datasheet, LT8643SIV-2#PBF pinout, LT8643SIV-2#PBF application, or LT8643SIV-2#PBF equivalent, key selection criteria include ultralow IQ regulation, external VC-loop compensation for fast transient response and current sharing, forced continuous or spread-spectrum operation modes, and thermal performance in 4mm × 4mm LQFN with exposed GND pad.
Technical Context
The LT8643SIV-2#PBF implements peak current mode control with a dedicated VC error amplifier output for external compensation-enabling precise loop tuning, multi-phase current sharing, and optimized transient response at switching frequencies up to 3MHz. Its Silent Switcher architecture integrates split VIN paths and internal hot-loop minimization to suppress radiated EMI without requiring external shielding.
It supports four SYNC/MODE-configurable operating states: Burst Mode (ultralow IQ), Forced Continuous Mode (full-frequency operation), Spread Spectrum (±22% frequency dithering), and external clock synchronization. The 30ns minimum on-time enables high step-down ratios (e.g., 42V→3.3V) at 2MHz, while low dropout (100mV @ 1A) ensures stable regulation under high-load, low-VIN conditions.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 3.4V to 42V - supports wide automotive battery transients and industrial input rails without pre-regulation. |
| Output Current | 6A continuous, 7A peak - sustains full load across –40°C to 125°C junction temperature range. |
| Quiescent Current | 2.5µA @ 12VIN→3.3VOUT in Burst Mode - enables always-on systems with multi-year battery life. |
| Switching Frequency | 200kHz to 3MHz (RT-programmable) - allows optimization of size vs. efficiency; 2MHz enables <3mm² inductor solutions. |
| Minimum On-Time | 30ns - enables direct 42V-to-3.3V conversion at 2MHz without cascaded stages. |
| Feedback Reference | 0.970V ±0.006V - tight tolerance reduces output voltage drift over temperature and line/load. |
| EMI Performance | CISPR 25 Class 5 compliant with spread spectrum - eliminates need for ferrite beads or metal shields in automotive ECU designs. |
Pinout & Package
LT8643SIV-2#PBF uses a 24-lead 4mm × 4mm × 0.94mm LQFN package with exposed GND pads (pins 25–28) for thermal management. Pin functions are validated per Analog Devices' Rev. D datasheet and DC2530A demo board layout.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| VC (22) | Error amplifier output | Direct access to control loop node for external RC compensation-enables fast transient response and parallel current sharing. |
| SYNC/MODE (20) | Operating mode selector | Configures Burst Mode (GND), FCM (floating), spread spectrum (3.4V), or external sync (clock input). |
| TR/SS (21) | Soft-start & tracking input | Programs output ramp rate via capacitor; enables power sequencing with other rails when driven externally. |
| PG (23) | Power good open-drain | Asserts high when FB is within ±7.5% of 0.97V reference-provides system-level power sequencing and fault indication. |
| BST (7) | Bootstrap supply | Drives high-side NMOS gate above VIN using 0.1µF ceramic capacitor-ensures full enhancement at high duty cycles. |
| SW (8–12) | Power switch node | Five paralleled SW pins reduce conduction loss and EMI; must be routed as single low-inductance node to inductor. |
| GND (3,16,22,25–28) | Ground return | Multiple GND connections-including 4-exposed-pad thermal path-minimize ground bounce and improve thermal resistance (θJC = 7°C/W). |
Key Features
| Feature | Design Value |
|---|---|
| Silent Switcher architecture | Integrated dual-input VIN paths and balanced SW routing cut radiated EMI by >30dB vs. conventional buck regulators. |
| External VC compensation | Enables custom loop bandwidth tuning and active current sharing across multiple LT8643S-2 units in high-current arrays. |
| Spread spectrum modulation | ±22% frequency dithering centered on RT-set frequency-reduces peak EMI amplitude without affecting regulation stability. |
| AEC-Q100 Grade I | Qualified for automotive ambient temperatures (–40°C to +125°C) with lifetime reliability validation per stress test protocols. |
| Low dropout operation | 100mV dropout at 1A load ensures regulation down to VIN = VOUT + 0.1V-critical for cold-crank 6V automotive scenarios. |
Applications
| Automotive ADAS Power Supply | Industrial PLC I/O Module |
|---|---|
Use Scenario: Powers image signal processor (ISP) and radar SoC in forward-facing camera module with strict CISPR 25 Class 5 EMI limits. IC Role / Device Role / Timing Role: Primary 5V/6A power rail generator with spread-spectrum EMI suppression and power-good sequencing. Use Value: Eliminates external EMI filters and metal shielding, reducing BOM cost and PCB area by >35% vs. non-Silent Switcher alternatives. |
Use Scenario: Supplies isolated 3.3V logic and 5V analog circuitry in DIN-rail mounted programmable logic controller. IC Role / Device Role / Timing Role: High-efficiency, wide-input DC/DC converter handling 9–36V industrial supply variations and 100% load steps. Use Value: 95% efficiency at 2MHz enables compact 1210-size inductors and passive cooling-no heatsink required at 6A full load. |
| Medical Imaging Sensor Hub | Telecom Remote Radio Unit |
Use Scenario: Powers low-noise analog front-end (AFE) and FPGA in portable ultrasound probe requiring ultralow ripple & noise. IC Role / Device Role / Timing Role: Low-EMI, low-ripple 3.3V/6A supply with <10mVP-P output ripple and sub-µA standby IQ. Use Value: Burst Mode IQ of 2.5µA extends battery runtime to >72 hours in handheld diagnostic devices. |
Use Scenario: Generates 5V/6A bias for GaN power amplifiers in 5G massive MIMO base station remote radio heads. IC Role / Device Role / Timing Role: High-reliability, thermally robust DC/DC stage operating continuously at 85°C ambient with forced air cooling. Use Value: θJA = 24°C/W on demo board enables 6A operation at 125°C junction temp-no derating needed below 85°C ambient. |
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-2#PBF | Internal compensation; 1.7µA Burst Mode IQ; no VC pin; identical pinout and package. | Lacks external loop tuning and current sharing capability-suited for fixed-output, single-rail applications. | Select when design requires lowest possible IQ and simpler compensation, not multi-phase or dynamic load response. |
| MPQ4433AGL-AEC1-P | 3.5V–36V input; 3.5A output; integrated compensation; 17µA IQ; QFN-16 package. | Lower current rating and no spread spectrum-requires external EMI filtering for automotive Class 5 compliance. | Choose for cost-sensitive, lower-power automotive modules where full 6A capability and ultra-low EMI are not required. |
Compared with LT8640SIV-2#PBF, the LT8643SIV-2#PBF trades slightly higher light-load IQ for essential VC-loop flexibility and current sharing; versus MPQ4433AGL-AEC1-P, it delivers 71% higher output current, 7x lower IQ, and built-in EMI suppression-justifying its use in high-performance, space-constrained automotive and industrial systems.
Availability
LT8643SIV-2#PBF is available at Aetrix Electronics and suitable for automotive ADAS power supplies, industrial PLC I/O modules, medical imaging sensor hubs, and telecom remote radio units requiring stable component supply, AEC-Q100 qualification, and long-term lifecycle support.
Supply support for LT8643SIV-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, Inc. is a global leader in high-performance analog, mixed-signal, and digital signal processing semiconductors, serving precision instrumentation, communications, and industrial markets since 1965.
The LT8643S-2 belongs to Analog Devices' Silent Switcher® family of high-efficiency, low-EMI DC/DC regulators-designed specifically for automotive, industrial, and medical applications demanding clean, reliable power in space- and noise-constrained environments.
FAQ
What is the maximum output current and thermal limit of the LT8643SIV-2#PBF?
The LT8643SIV-2#PBF delivers 6A continuous output current with guaranteed performance from –40°C to +125°C junction temperature. Its 4mm × 4mm LQFN package achieves θJC = 7°C/W (junction-to-case) and θJA = 24°C/W on a demo board, enabling full 6A operation at 125°C junction temperature with proper PCB copper area and airflow.
How does the VC pin on the LT8643SIV-2#PBF enable external compensation and current sharing?
The VC pin on the LT8643SIV-2#PBF provides direct access to the error amplifier output, allowing designers to add external RC networks for precise loop compensation. This enables faster transient response than internal-compensation variants and supports active current sharing across multiple LT8643SIV-2#PBF units by connecting their VC pins through small resistors-critical for high-current (>12A) applications.
Can the LT8643SIV-2#PBF operate with input voltages below 3.4V?
No-the LT8643SIV-2#PBF has a specified minimum input voltage of 3.4V per its Absolute Maximum Ratings and Electrical Characteristics tables. Operation below this threshold is not guaranteed and may result in regulation failure or undefined behavior; for sub-3.4V inputs, consider the LT8645S or other low-VIN buck regulators.
What are the key differences between LT8643SIV-2#PBF and LT8640SIV-2#PBF?
The LT8643SIV-2#PBF features external VC compensation (pin 22), enabling advanced loop tuning and current sharing, whereas the LT8640SIV-2#PBF uses internal compensation and lacks the VC pin. The LT8643SIV-2#PBF also has higher Burst Mode IQ (230µA vs. 1.7µA) due to VC circuitry but offers superior dynamic performance and flexibility in complex power systems.
Does the LT8643SIV-2#PBF support synchronization to an external clock source?
Yes-the SYNC/MODE pin (pin 20) of the LT8643SIV-2#PBF accepts an external clock signal to synchronize switching frequency. When driven with a clean CMOS clock, the device operates in forced continuous mode at the external frequency, eliminating beat frequencies in multi-rail systems and simplifying EMI filter design in synchronized power architectures.
LT8643SIV-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)
LT8643SIV-2#PBF FAQ
1.How can I place an order for LT8643SIV-2#PBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LT8643SIV-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 LT8643SIV-2#PBF reliable?
The price and inventory of LT8643SIV-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 LT8643SIV-2#PBF is usually 5 days.
3.What payment methods are accepted for LT8643SIV-2#PBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LT8643SIV-2#PBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LT8643SIV-2#PBF?
LT8643SIV-2#PBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LT8643SIV-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 LT8643SIV-2#PBF?
For technical support, including LT8643SIV-2#PBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LT8643SIV-2#PBF requirements.
6.How does Aetrix verify that LT8643SIV-2#PBF is sourced from the original manufacturer or authorized distributors?
All LT8643SIV-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 LT8643SIV-2#PBF meets industry standards.
7.What is the process for return or replacement of LT8643SIV-2#PBF?
All LT8643SIV-2#PBF units undergo pre-shipment inspection (PSI). If there is an issue with LT8643SIV-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 LT8643SIV-2#PBF part is unused and in its original packaging.
Return procedure for LT8643SIV-2#PBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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