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Analog Devices Inc. LT8643SIV#TRPBF
- Part No.:
- LT8643SIV#TRPBF
- Manufacturer:
- Analog Devices Inc.
- Package:
- 24-TFQFN Exposed Pad
- Datasheet:
-
LT8643SIV#TRPBF.pdf
- Description:
- IC REG BUCK ADJ 6A 24LQFN
- Quantity:
- Payment:
- Shipping:
Inventory:1,170
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Product details
Overview
LT8643SIV#TRPBF from Analog Devices is a 42V, 6A synchronous step-down DC/DC regulator with external compensation, Silent Switcher® 2 architecture, 2.5µA quiescent current in Burst Mode, and 30ns minimum on-time. It delivers up to 95% efficiency at 2MHz (12VIN→5VOUT) and targets noise-sensitive automotive and industrial power rails requiring low EMI and fast transient response.
For engineers reviewing the LT8643SIV#TRPBF datasheet, LT8643SIV#TRPBF pinout, LT8643SIV#TRPBF application, or LT8643SIV#TRPBF equivalent, this page provides verified technical context, package mapping, real-world EMI performance data, external loop compensation guidance, and validated automotive-grade alternatives for high-reliability 5V/6A point-of-load designs.
Technical Context
The LT8643SIV#TRPBF implements peak current mode control with a 30ns minimum on-time, enabling high step-down ratios (e.g., 36VIN→3.3VOUT) at 2–3MHz switching frequencies. Its external VC pin allows full control of error amplifier transconductance (1.7mS), gain (260), source/sink current (±350µA), and clamp voltage (2.6V) for precise loop tuning.
Silent Switcher 2 architecture integrates internal bypass capacitors on VIN, BST, and INTVCC pins, minimizing PCB layout sensitivity and achieving CISPR 25 Class 5 radiated EMI compliance without external filters. Spread spectrum modulation (22% range, 3kHz center) further reduces peak emissions in fixed-frequency or sync modes.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 3.4V to 42V - supports wide automotive battery transients (cold crank, load dump) and industrial 24/36V rails. |
| Output Current | 6A continuous, 7A peak - sustains full load across –40°C to 125°C junction temperature with proper thermal design. |
| 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 (small inductors) vs. efficiency (1MHz optimal for 12VIN→5VOUT). |
| Feedback Reference | 0.970V ±0.006V - tight tolerance enables accurate output regulation; line regulation <0.02%/V ensures stability over input range. |
| EMI Performance | CISPR 25 Class 5 compliant (radiated & conducted) with integrated caps - eliminates need for external EMI filter in most automotive layouts. |
| Min On-Time | 30ns - enables 36VIN→3.3VOUT conversion at 2MHz without pulse-skipping artifacts. |
Pinout & Package
LT8643SIV#TRPBF uses a 24-lead 4mm × 4mm × 0.94mm LQFN package with exposed GND pads (pins 25–28) for thermal management. θJA = 38°C/W (JEDEC board), θJC(PAD) = 7°C/W.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| BIAS (1) | Internal regulator supply | Tie to VOUT (≥3.3V) to reduce VIN current draw; enables low-noise biasing of power switches. |
| VC (22) | Error amplifier output | External RC network sets loop bandwidth and phase margin; required for current sharing and fast transient response. |
| SYNC/MODE (20) | Operating mode selector | GND = Burst Mode; float = FCM; INTVCC = spread spectrum; external clock = sync - no external logic needed. |
| TR/SS (21) | Soft-start & tracking control | 1.9µA internal pull-up enables capacitor-programmed slew rate; supports power sequencing with other rails. |
| PG (23) | Power good indicator | Open-drain output asserts when FB is within ±8% of 0.97V and no fault (UVLO, thermal, EN/UV low). |
| FB (24) | Feedback reference node | Regulated to 0.970V; connect resistor divider tap here; add 4.7–22pF phase lead cap to VOUT for stability. |
Key Features
| Feature | Design Value |
|---|---|
| Silent Switcher 2 architecture | Integrated VIN/BST/INTVCC bypass capacitors eliminate layout-dependent EMI spikes and simplify PCB routing. |
| External compensation (VC pin) | Enables precise loop tuning for <10µs load transient recovery and parallel operation with current sharing. |
| Burst Mode with 2.5µA IQ | Maintains regulation at µA-level loads while suppressing switching noise - critical for always-on telematics modules. |
| Spread spectrum modulation | Reduces peak radiated emissions by >10dB across 100–1000MHz band without sacrificing efficiency or thermal performance. |
| AEC-Q100 Grade 1 qualified | Validated for –40°C to 125°C operation with automotive reliability testing - suitable for engine control, ADAS, and infotainment. |
Applications
| Automotive Infotainment Power | Industrial PLC I/O Module |
|---|---|
Use Scenario: Powering 5V/4A SoC and DDR memory in head unit with strict CISPR 25 Class 5 EMI limits. IC Role / Device Role / Timing Role: Primary 5V buck converter with external compensation for dynamic load handling during video decode bursts. Use Value: Eliminates external EMI filter, reduces BOM cost by $0.32, and achieves 95% efficiency at 2MHz switching. |
Use Scenario: Generating stable 5V rail for isolated analog I/O channels in harsh factory environments. IC Role / Device Role / Timing Role: High-reliability point-of-load regulator with AEC-Q100 qualification and 42V input tolerance. Use Value: Survives 40V load-dump transients without shutdown; maintains regulation during 100ms brownouts down to 3.4V. |
| Medical Imaging Sensor Bias | EV Battery Management System |
Use Scenario: Low-noise 3.3V/2A supply for CMOS image sensor array in portable ultrasound devices. IC Role / Device Role / Timing Role: Ultra-low IQ buck converter operating in Burst Mode between imaging frames. Use Value: 2.5µA quiescent current extends battery runtime by 38% vs. comparable 5µA alternatives. |
Use Scenario: 5V/6A auxiliary supply for microcontroller, CAN transceiver, and cell monitoring ICs in BMS mainboard. IC Role / Device Role / Timing Role: Robust primary regulator with reverse-current protection and thermal foldback. Use Value: Safely handles reverse current during cell balancing; thermal shutdown activates only above 150°C junction. |
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#TRPBF | Internal compensation; 5A continuous (7A peak); same package and pinout; 1.7µA IQ in Burst Mode. | Lower output current; simpler design for fixed 5A loads without current sharing or aggressive transient requirements. | Select when loop stability is prioritized over transient speed and current sharing is unnecessary. |
| MPQ4433AGL-AEC1-Z | Monolithic 42V/6A buck; 2.5µA IQ; AEC-Q100 Grade 1; but no spread spectrum or Silent Switcher architecture. | Higher radiated EMI requires external filter; lacks VC pin for external loop tuning; lower efficiency at 2MHz (92% vs. 95%). | Select for cost-sensitive automotive applications where EMI filtering is acceptable and loop tuning flexibility is not required. |
Compared with LT8643SIV#TRPBF, LT8640SIV#TRPBF offers simpler implementation but sacrifices fast transient response and current sharing capability, while MPQ4433AGL-AEC1-Z meets automotive qualification but requires additional EMI mitigation and delivers lower efficiency at high frequencies.
Availability
LT8643SIV#TRPBF is available at Aetrix Electronics and suitable for automotive infotainment systems, industrial PLCs, medical imaging sensors, and EV battery management systems requiring stable component supply, AEC-Q100 qualification, and ultra-low EMI emissions.
Supply support for LT8643SIV#TRPBF 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 LT864xS family delivers Silent Switcher 2 power conversion for noise-sensitive applications, combining high efficiency, ultra-low IQ, and automotive-grade reliability in compact monolithic packages.
FAQ
What is the minimum input voltage for stable operation of the LT8643SIV#TRPBF?
The LT8643SIV#TRPBF has a guaranteed minimum input voltage of 3.4V across its full operating temperature range (–40°C to 125°C). At 25°C, it can start regulation as low as 3.0V, but system designs must respect the 3.4V specification for robust automotive and industrial use. Below this threshold, UVLO disables switching and pulls PG low.
How does the VC pin on the LT8643SIV#TRPBF enable current sharing between multiple converters?
The VC pin on the LT8643SIV#TRPBF serves as the error amplifier output, allowing direct connection of VC nodes via small resistors to force equal peak inductor currents. This external compensation path-combined with synchronized switching-enables precise current sharing among paralleled LT8643SIV#TRPBF units without additional master-slave circuitry.
Can the LT8643SIV#TRPBF operate without connecting the BIAS pin?
Yes, the LT8643SIV#TRPBF can operate with BIAS tied to GND, but this increases VIN current draw and reduces efficiency-especially at high input voltages or switching frequencies. For optimal performance, BIAS should be connected to VOUT (≥3.3V) or an external ≥3.3V supply, with a 1µF local bypass capacitor if not using VOUT.
What is the maximum achievable switching frequency when using the RT pin on the LT8643SIV#TRPBF?
The LT8643SIV#TRPBF supports switching frequencies up to 3MHz, set by connecting an 18.2kΩ resistor from RT to GND. At 3MHz, the device maintains >90% efficiency (12VIN→5VOUT, 2A load) and retains full Burst Mode functionality, though thermal management becomes more critical due to higher core losses.
Does the LT8643SIV#TRPBF require external components for EMI compliance in automotive applications?
No-the LT8643SIV#TRPBF's Silent Switcher 2 architecture, with integrated VIN/BST/INTVCC bypass capacitors and optimized internal current loops, achieves CISPR 25 Class 5 radiated and conducted EMI compliance on standard 4-layer PCBs without external filters. Spread spectrum modulation further lowers peak emissions by up to 10dB when enabled via SYNC/MODE.
LT8643SIV#TRPBF Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- -
- Package/Case:
- 24-TFQFN Exposed Pad
- Packaging:
- Tape & Reel (TR)
- 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#TRPBF FAQ
1.How can I place an order for LT8643SIV#TRPBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LT8643SIV#TRPBF 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#TRPBF reliable?
The price and inventory of LT8643SIV#TRPBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LT8643SIV#TRPBF is usually 5 days.
3.What payment methods are accepted for LT8643SIV#TRPBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LT8643SIV#TRPBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LT8643SIV#TRPBF?
LT8643SIV#TRPBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LT8643SIV#TRPBF 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#TRPBF?
For technical support, including LT8643SIV#TRPBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LT8643SIV#TRPBF requirements.
6.How does Aetrix verify that LT8643SIV#TRPBF is sourced from the original manufacturer or authorized distributors?
All LT8643SIV#TRPBF 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#TRPBF meets industry standards.
7.What is the process for return or replacement of LT8643SIV#TRPBF?
All LT8643SIV#TRPBF units undergo pre-shipment inspection (PSI). If there is an issue with LT8643SIV#TRPBF, 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#TRPBF part is unused and in its original packaging.
Return procedure for LT8643SIV#TRPBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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