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Analog Devices Inc. LT8645SIV#WPBF
- Part No.:
- LT8645SIV#WPBF
- Manufacturer:
- Analog Devices Inc.
- Package:
- 32-TFQFN Exposed Pad
- Datasheet:
-
LT8645SIV#WPBF.pdf
- Description:
- IC REG BUCK ADJ 8A 32LQFN
- Quantity:
- Payment:
- Shipping:
Inventory:3,455
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Product details
Overview
LT8645SIV#WPBF from Analog Devices is a 65V, 8A synchronous step-down Silent Switcher 2 regulator with 2.5µA quiescent current in Burst Mode, internal compensation, and AEC-Q100 qualification for automotive applications. It delivers up to 95% efficiency at 1MHz (12VIN→5VOUT), features 40ns minimum on-time, and operates across 3.4V–65V input range in a 32-lead 6mm × 4mm LQFN package.
For engineers reviewing the LT8645SIV#WPBF datasheet, LT8645SIV#WPBF pinout, LT8645SIV#WPBF application, or LT8645SIV#WPBF equivalent, key selection considerations include ultralow EMI performance without layout sensitivity, internal bypass capacitors, spread spectrum modulation support, and automotive-grade thermal reliability up to 125°C junction temperature.
Technical Context
The LT8645SIV#WPBF employs peak current mode control with second-generation Silent Switcher 2 architecture, integrating internal VIN, BST, and INTVCC bypass capacitors to minimize radiated EMI and eliminate PCB layout sensitivity. Its 40ns minimum on-time enables high step-down ratios at switching frequencies up to 2.2MHz.
Burst Mode® operation achieves 2.5µA IQ regulating 12VIN to 3.3VOUT, while pulse-skipping and spread spectrum modes provide flexible low-load and EMI-reduction strategies. The device includes integrated soft-start, output tracking, and power-good monitoring with ±8% FB threshold accuracy.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 3.4V to 65V - supports wide-range industrial and automotive battery inputs including 12V, 24V, 36V, and 48V systems. |
| Output Current | 8A continuous - delivers full rated load without external current sharing or parallel configuration. |
| Quiescent Current (Burst Mode) | 2.5µA at 12VIN→3.3VOUT - enables >10-year battery life in always-on automotive modules. |
| Switching Frequency Range | 200kHz to 2.2MHz - programmable via RT resistor; allows optimization of size vs. efficiency vs. EMI. |
| Minimum On-Time | 40ns - enables 12VIN→1.0VOUT conversion at 2MHz, supporting high-ratio point-of-load regulation. |
| Feedback Reference Voltage | 0.97V ±0.006V - tight tolerance ensures <±0.1% output voltage accuracy under line/load/temperature variation. |
| EMI Performance | CISPR 25 Class 5 compliant - meets stringent automotive radiated emission limits without external filters. |
| Thermal Rating | –40°C to 125°C junction - AEC-Q100 qualified for under-hood automotive use with θJC(PAD) = 4.4°C/W. |
Pinout & Package
LT8645SIV#WPBF is housed in a 32-lead LQFN package (6mm × 4mm × 0.94mm) with exposed thermal pad (Pins 33–38, GND). The package is RoHS-compliant, Au-finished (e4), and MSL Level 3.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| VIN (Pins 4,5,6,21,22,23) | Main input power supply | Multiple parallel pins reduce IR drop and thermal resistance; requires ≥4.7µF local ceramic bypass per group. |
| GND (Pins 8,9,10,17,18,19,33–38) | Power and signal reference ground | Exposes 6 dedicated GND pads + 6 exposed thermal pad pins - must be soldered to PCB for θJC(PAD) = 4.4°C/W. |
| SW (Pins 12,13,14,15,16) | Power switch node | Five paralleled SW outputs reduce conduction loss and EMI loop area; connects directly to inductor and BST capacitor. |
| FB (Pin 32) | Feedback sensing input | Regulates to 0.97V reference; requires 1–10pF phase-lead capacitor between FB and VOUT for stability. |
| EN/UV (Pin 25) | Enable and undervoltage lockout | Hysteretic threshold (1.01V rise / 0.965V fall) enables reliable startup and brownout protection. |
| RT (Pin 26) | Frequency programming | Resistor-to-ground sets fSW from 200kHz to 2.2MHz; 60.4kΩ yields ~1MHz for typical 5V/8A design. |
| SYNC/MODE (Pin 28) | Operating mode control | Ground = Burst Mode; float = pulse-skipping; INTVCC = spread spectrum; external clock = synchronization. |
| TR/SS (Pin 29) | Soft-start and output tracking | 1.9µA internal pull-up enables RC-programmed slew rate; supports sequencing with other rails via external voltage source. |
Key Features
| Feature | Design Value |
|---|---|
| Silent Switcher 2 Architecture | Integrated VIN/BST/INTVCC ceramic capacitors minimize fast-current-loop area, enabling CISPR 25 Class 5 compliance on standard 2-layer PCBs. |
| Ultralow Quiescent Current | 2.5µA IQ in Burst Mode extends battery runtime in always-on automotive ECUs, telematics, and ADAS sensors. |
| Internal Compensation | Eliminates external compensation network - simplifies design, reduces BOM count, and ensures stable operation across all loads and temperatures. |
| Spread Spectrum Modulation | 24% frequency dithering reduces peak EMI by >10dB, easing compliance testing without added filter components. |
| AEC-Q100 Grade I | Qualified for –40°C to +125°C operation with full characterization and reliability testing per automotive standards. |
| Low Dropout Performance | 60mV dropout at 1A enables high-efficiency regulation near input rail - critical for 12VIN→11.5VOUT pre-regulator applications. |
Applications
| Automotive Infotainment Power | Industrial PLC I/O Module Supply |
|---|---|
|
Use Scenario: Powering 5V/3A display controller and audio codec in head unit with 12V battery input subject to cold-crank (4.5V) and load-dump (60V) transients. IC Role / Device Role / Timing Role: Primary 5V buck converter with input overvoltage clamping, burst-mode sleep during vehicle off-state, and PG signaling to MCU. Use Value: Eliminates need for external EMI filter and input TVS due to integrated caps and 65V rating - reduces board area by 35% vs. legacy solutions. |
Use Scenario: Generating isolated 5V/5A supply for digital I/O expansion cards in modular PLC chassis with 24VDC field bus input. IC Role / Device Role / Timing Role: High-current point-of-load regulator with adjustable fSW (500kHz–1.5MHz) to avoid noise coupling into analog sensor channels. Use Value: 94% efficiency at 2MHz enables compact 1µH inductor and 100µF output cap - achieves 12cm² solution size including thermal pad. |
| GSM Base Station RF Power Amplifier Bias | Medical Imaging Sensor Interface Supply |
|
Use Scenario: Providing clean, low-noise 5V/4A bias for GaN PA stages in small-cell base stations operating from 48V telecom rectifier. IC Role / Device Role / Timing Role: EMI-critical front-end buck with spread spectrum enabled and CLKOUT synchronized to system clock for deterministic noise placement. Use Value: Radiated emissions reduced by 15dB at 150MHz vs. fixed-frequency mode - passes EN 55032 Class A without shielding. |
Use Scenario: Powering low-noise 3.3V/2A ADC driver and FPGA I/O banks in portable ultrasound probe with Li-ion battery (3.0–4.2V) input. IC Role / Device Role / Timing Role: Wide-input buck with TR/SS tracking to sequence with 1.2V core rail and PG confirmation before data acquisition. Use Value: 2.5µA quiescent current extends single-charge battery life to 14 days in standby - exceeds IEC 62304 low-power 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 |
|---|---|---|---|
| LT8645SEV#WPBF | Same silicon, extended temperature grade (–40°C to +125°C guaranteed), identical pinout and electrical specs. | Targeted for under-hood automotive applications requiring full spec guarantee across full temp range. | Select LT8645SEV#WPBF when full AEC-Q100 temperature validation and production traceability are required. |
| LT8640SIV#PBF | Lower current (6A), same 65V rating and Silent Switcher 2 architecture, but no spread spectrum or CLKOUT. | Suitable for cost-sensitive industrial applications where 8A headroom and advanced EMI features are unnecessary. | Choose LT8640SIV#PBF for 5V/6A designs where footprint compatibility is needed but full feature set is not required. |
Compared with LT8645SEV#WPBF, the LT8645SIV#WPBF shares identical functionality but is specified for the standard industrial temperature range; versus LT8640SIV#PBF, it adds 2A current headroom, spread spectrum, and CLKOUT-enabling higher-reliability automotive and EMI-critical designs.
Availability
LT8645SIV#WPBF is available at Aetrix Electronics and suitable for automotive infotainment systems, industrial PLC power supplies, and medical imaging equipment requiring stable component supply with AEC-Q100 qualification and long-term lifecycle support.
Supply support for LT8645SIV#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 industrial, automotive, communications, and healthcare markets since 1965.
The LT8645S/LT8646S product line delivers high-efficiency, ultralow-EMI DC/DC conversion for automotive and industrial applications demanding robustness, small size, and regulatory compliance without design compromises.
FAQ
What is the maximum input voltage rating for the LT8645SIV#WPBF?
The LT8645SIV#WPBF has an absolute maximum input voltage rating of 65V, with guaranteed operation from 3.4V to 65V. This enables direct connection to 48V industrial buses and automotive battery systems experiencing load dump transients, eliminating the need for upstream overvoltage protection in most designs.
Does the LT8645SIV#WPBF require external compensation components?
No, the LT8645SIV#WPBF uses internal compensation, which eliminates external RC networks typically needed for loop stability. This simplifies layout, reduces bill-of-materials cost, and ensures consistent performance across temperature and manufacturing variance without tuning.
How does the LT8645SIV#WPBF achieve ultralow EMI without external filters?
The LT8645SIV#WPBF integrates ceramic bypass capacitors for VIN, BST, and INTVCC within the LQFN package, minimizing high-di/dt loop areas. Combined with symmetrical layout and Silent Switcher 2 edge-rate control, this enables CISPR 25 Class 5 compliance on standard 2-layer PCBs without ferrite beads or common-mode chokes.
What is the purpose of the exposed thermal pad (Pins 33–38) on the LT8645SIV#WPBF?
The six exposed thermal pad pins (33–38) on the LT8645SIV#WPBF are internally connected to GND and must be soldered to a large PCB copper pour for optimal thermal performance. This achieves θJC(PAD) = 4.4°C/W, enabling 8A continuous operation at 125°C junction temperature with minimal heatsinking.
Can the LT8645SIV#WPBF synchronize to an external clock source?
Yes, the LT8645SIV#WPBF supports external synchronization via the SYNC/MODE pin (Pin 28). When driven with a TTL/CMOS clock signal, the device locks its internal oscillator to the external frequency and operates in pulse-skipping mode - enabling deterministic EMI reduction and multi-rail timing coordination.
LT8645SIV#WPBF Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- Silent Switcher®2
- Package/Case:
- 32-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):
- 65V
- Voltage - Output (Min/Fixed):
- 0.97V
- Voltage - Output (Max):
- 65V
- Current - Output:
- 8A
- Frequency - Switching:
- 200kHz ~ 2.2MHz
- Synchronous Rectifier:
- Yes
- Operating Temperature:
- -40°C ~ 125°C (TJ)
- Grade:
- Automotive
- Qualification:
- AEC-Q100
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 32-LQFN (6x4)
LT8645SIV#WPBF FAQ
1.How can I place an order for LT8645SIV#WPBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LT8645SIV#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 LT8645SIV#WPBF reliable?
The price and inventory of LT8645SIV#WPBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LT8645SIV#WPBF is usually 5 days.
3.What payment methods are accepted for LT8645SIV#WPBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LT8645SIV#WPBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LT8645SIV#WPBF?
LT8645SIV#WPBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LT8645SIV#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 LT8645SIV#WPBF?
For technical support, including LT8645SIV#WPBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LT8645SIV#WPBF requirements.
6.How does Aetrix verify that LT8645SIV#WPBF is sourced from the original manufacturer or authorized distributors?
All LT8645SIV#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 LT8645SIV#WPBF meets industry standards.
7.What is the process for return or replacement of LT8645SIV#WPBF?
All LT8645SIV#WPBF units undergo pre-shipment inspection (PSI). If there is an issue with LT8645SIV#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 LT8645SIV#WPBF part is unused and in its original packaging.
Return procedure for LT8645SIV#WPBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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