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Analog Devices Inc. LT8646SIV#WPBF
- Part No.:
- LT8646SIV#WPBF
- Manufacturer:
- Analog Devices Inc.
- Package:
- 32-TFQFN Exposed Pad
- Datasheet:
-
LT8646SIV#WPBF.pdf
- Description:
- IC REG BUCK ADJ 8A 32LQFN
- Quantity:
- Payment:
- Shipping:
Inventory:1,255
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Product details
Overview
LT8646SIV#WPBF from Analog Devices is a 65V input, 8A synchronous step-down Silent Switcher 2 regulator with external compensation, 40ns minimum on-time, 2.5µA quiescent current in Burst Mode, and AEC-Q100 automotive qualification. It delivers up to 95% efficiency at 1MHz (12VIN→5VOUT) and operates from 3.4V to 65V input in harsh environments such as automotive infotainment power supplies.
For engineers reviewing the LT8646SIV#WPBF datasheet, LT8646SIV#WPBF pinout, LT8646SIV#WPBF application, or LT8646SIV#WPBF equivalent, key selection criteria include ultralow EMI emissions (CISPR 25 Class 5 compliant), external loop compensation for fast transient response, spread spectrum modulation capability, and thermal performance with θJC(PAD) = 4.4°C/W in the 6mm × 4mm LQFN package.
Technical Context
The LT8646SIV#WPBF implements peak current mode control with a dedicated VC error amplifier output for external compensation-enabling precise current sharing across parallel converters and optimized transient response at switching frequencies up to 2.2MHz. Its second-generation Silent Switcher 2 architecture integrates internal bypass capacitors on VIN, BST, and INTVCC pins to minimize high-di/dt loop area and eliminate layout sensitivity for radiated EMI.
Burst Mode operation reduces input quiescent current to 230µA (BIAS = 0V) or 25µA (BIAS = 5V), while pulse-skipping and spread spectrum modes provide flexible low-load efficiency and EMI reduction strategies. The 40ns minimum on-time supports high step-down ratios (e.g., 48V→3.3V at 2MHz) without pulse skipping.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 3.4V to 65V - supports wide-range industrial and automotive battery inputs including cold-crank (6V) and load-dump (60V+). |
| Output Current | 8A continuous - enables single-chip 5V/8A or 3.3V/8A conversion without external MOSFETs or current sharing. |
| Quiescent Current | 2.5µA in Burst Mode (12VIN→3.3VOUT) - extends battery life in always-on automotive modules. |
| Switching Frequency | 200kHz to 2.2MHz - programmable via RT resistor; allows optimization of size (high-freq) vs. efficiency (low-freq). |
| Min On-Time | 40ns - enables high input-to-output voltage ratios (e.g., 48V→3.3V) at 2MHz without duty-cycle limitation. |
| EMI Performance | CISPR 25 Class 5 compliant - meets stringent automotive radiated emission limits without external filters in typical layouts. |
| Thermal Resistance | θJC(PAD) = 4.4°C/W - enables >6W power dissipation with minimal junction-to-pad temperature rise under full load. |
Pinout & Package
LT8646SIV#WPBF uses a 32-lead 6mm × 4mm × 0.94mm LQFN package with exposed thermal pad (Pins 33–38, GND). The package footprint matches standard 6mm × 4mm QFN layouts and supports JEDEC-compliant reflow (260°C max).
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| VIN (Pins 4,5,6,21,22,23) | Main input power supply | Must be locally bypassed with ≥4.7µF capacitor; multiple pins reduce IR drop and improve high-current path integrity. |
| GND (Pins 8,9,10,17,18,19,33–38) | Power and signal ground reference | Exposed pad (33–38) must be soldered to PCB ground plane for thermal and EMI performance; not optional. |
| SW (Pins 12,13,14,15,16) | Switch node output | High di/dt node; requires minimized copper area and direct connection to inductor and BST capacitor to suppress EMI. |
| VC (Pin 30) | Error amplifier output | External compensation point: connect RC network to ground to set loop bandwidth and phase margin for fast transient response. |
| EN/UV (Pin 25) | Enable and undervoltage lockout | Hysteretic threshold (0.965V/1.01V) enables reliable startup and brownout protection without external circuitry. |
| SYNC/MODE (Pin 28) | Operating mode selector | Configures Burst Mode (GND), pulse-skipping (float), spread spectrum (3–4V), or external sync (clock input). |
| TR/SS (Pin 29) | Soft-start and tracking control | Internal 1.9µA pull-up enables capacitor-programmed slew rate; supports output voltage tracking during power sequencing. |
| FB (Pin 32) | Feedback reference input | Regulates to 0.97V ±0.6%; connects to resistor divider; requires 1–10pF phase-lead capacitor to VOUT for stability. |
Key Features
| Feature | Design Value |
|---|---|
| Silent Switcher 2 Architecture | Integrated VIN/BST/INTVCC bypass capacitors eliminate layout-dependent EMI; achieves CISPR 25 Class 5 compliance on standard 4-layer PCBs. |
| External Compensation (VC Pin) | Enables precise loop tuning for multi-phase current sharing and <50µs load transient recovery at 8A step change. |
| Ultralow Quiescent Current | 2.5µA IQ in Burst Mode (12VIN→3.3VOUT) sustains >1-year battery life in always-on telematics modules. |
| Spread Spectrum Modulation | 24% frequency dithering reduces peak EMI by >10dB at fundamental and harmonics without affecting regulation accuracy. |
| AEC-Q100 Grade I | Qualified from –40°C to +125°C junction temperature; supports under-hood automotive applications with validated reliability data. |
Applications
| Automotive Infotainment Power | Industrial PLC I/O Module Supply |
|---|---|
Use Scenario: Powering 5V/3A display controller and 3.3V/2A MCU in head-unit systems with 9–16V battery input and load-dump transients. IC Role / Device Role / Timing Role: Primary synchronous buck regulator delivering regulated 5V and 3.3V rails with integrated EMI suppression and thermal robustness. Use Value: Eliminates need for external EMI filters and heatsinks; maintains regulation during 65V load-dump events per ISO 7637-2. | Use Scenario: Generating isolated 5V/6A auxiliary supply for digital I/O cards in factory automation controllers with 24VDC input. IC Role / Device Role / Timing Role: High-efficiency, high-reliability DC/DC converter operating continuously at 6A with minimal derating. Use Value: Delivers 94% efficiency at 2MHz (12VIN→5VOUT), enabling compact 25mm² solution size and <40°C case rise at full load. |
| GSM Base Station RF Power Amp Bias | Test Equipment DC Power Module |
Use Scenario: Providing clean, low-noise 5V bias for GaN RF power amplifiers in small-cell base stations with 48V backplane input. IC Role / Device Role / Timing Role: Low-EMI, high-PoL buck converter with spread spectrum enabled to avoid interference with sensitive RF receivers. Use Value: Radiated emissions reduced by 15dB below CISPR 25 Class 5 limit at 200–1000MHz, eliminating costly shielding. | Use Scenario: Programmable 3.3V/8A output stage in benchtop power supplies requiring fast transient response and remote sensing. IC Role / Device Role / Timing Role: Precision-regulated, externally compensated buck stage supporting dynamic load steps up to 8A with <100mV deviation. Use Value: VC pin enables custom loop compensation for <30µs recovery from 0→8A load step, meeting test equipment specification. |
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 |
|---|---|---|---|
| LT8645SIV#WPBF | Internal compensation; 2.5µA IQ (vs. 230µA in LT8646S sleep); no VC pin; identical pinout and package. | Optimized for fixed-output, space-constrained designs where loop tuning is unnecessary. | Select LT8645SIV#WPBF when external compensation is not required and lowest possible quiescent current is critical. |
| MPQ4470AGL-AEC1-Z | 40V max input; 7A output; 1.5µA IQ; no spread spectrum; QFN-16 package (smaller, fewer pins). | Limited to lower-voltage automotive systems; lacks Silent Switcher EMI performance and high-ratio capability. | Select MPQ4470AGL-AEC1-Z only for cost-sensitive 12V/24V applications where 65V rating and CISPR 25 Class 5 are not required. |
Compared with LT8645SIV#WPBF, the LT8646SIV#WPBF trades slightly higher light-load IQ for design flexibility via VC-based loop control and current sharing-making it superior for high-performance, multi-rail, or paralleled configurations. Against MPQ4470AGL-AEC1-Z, it provides significantly wider input range, higher output current, and certified EMI performance essential for demanding automotive and industrial use cases.
Availability
LT8646SIV#WPBF is available at Aetrix Electronics and suitable for automotive infotainment systems, industrial PLC power modules, and GSM base station RF bias supplies requiring stable component supply, AEC-Q100 qualification, and long-term production continuity.
Supply support for LT8646SIV#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.
The LT8646SIV#WPBF belongs to the Silent Switcher 2 family of high-efficiency, low-EMI DC/DC regulators designed specifically for automotive and industrial applications where electromagnetic compatibility, thermal resilience, and wide-input operation are mandatory.
FAQ
What is the maximum input voltage rating for the LT8646SIV#WPBF?
The LT8646SIV#WPBF has an absolute maximum input voltage rating of 65V on the VIN pins. It is specified to operate continuously over an input range of 3.4V to 65V, making it suitable for automotive battery systems subject to load-dump transients. Operation above 65V may cause permanent damage and is not supported.
How does the VC pin on the LT8646SIV#WPBF enable external compensation?
The VC pin on the LT8646SIV#WPBF is the output of the internal error amplifier and serves as the control node for peak switch current. By connecting an RC network from VC to GND, designers set the loop's dominant pole and zero to optimize phase margin and transient response-critical for current sharing in parallel configurations and fast load-step recovery in the LT8646SIV#WPBF.
Can the LT8646SIV#WPBF achieve CISPR 25 Class 5 radiated emissions compliance without external EMI filters?
Yes-the LT8646SIV#WPBF's Silent Switcher 2 architecture, with integrated bypass capacitors and optimized internal layout, enables CISPR 25 Class 5 radiated emissions compliance on standard 4-layer PCBs without external filters. Verified test data (Figure G49–G51) shows >10dB margin below the Class 5 peak limit at 100–1000MHz when using the recommended demo board layout and spread spectrum mode.
What is the thermal performance difference between the LT8646SIV#WPBF and LT8645SIV#WPBF packages?
Both the LT8646SIV#WPBF and LT8645SIV#WPBF use identical 32-lead 6mm × 4mm LQFN packages with exposed thermal pads. Their thermal resistance values are identical: θJC(PAD) = 4.4°C/W and θJA = 17°C/W on demo boards. The difference lies in functional implementation-not package thermals-so thermal design guidelines apply equally to both parts.
Does the LT8646SIV#WPBF support synchronization to an external clock source?
Yes-the LT8646SIV#WPBF supports external clock synchronization via the SYNC/MODE pin (Pin 28). When driven with a TTL/CMOS-compatible clock signal, the device synchronizes its internal oscillator to the external frequency while operating in pulse-skipping mode. This eliminates beat frequencies in multi-converter systems and simplifies EMI filtering in tightly spaced power domains.
LT8646SIV#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):
- 3.4V
- 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)
LT8646SIV#WPBF FAQ
1.How can I place an order for LT8646SIV#WPBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LT8646SIV#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 LT8646SIV#WPBF reliable?
The price and inventory of LT8646SIV#WPBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LT8646SIV#WPBF is usually 5 days.
3.What payment methods are accepted for LT8646SIV#WPBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LT8646SIV#WPBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LT8646SIV#WPBF?
LT8646SIV#WPBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LT8646SIV#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 LT8646SIV#WPBF?
For technical support, including LT8646SIV#WPBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LT8646SIV#WPBF requirements.
6.How does Aetrix verify that LT8646SIV#WPBF is sourced from the original manufacturer or authorized distributors?
All LT8646SIV#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 LT8646SIV#WPBF meets industry standards.
7.What is the process for return or replacement of LT8646SIV#WPBF?
All LT8646SIV#WPBF units undergo pre-shipment inspection (PSI). If there is an issue with LT8646SIV#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 LT8646SIV#WPBF part is unused and in its original packaging.
Return procedure for LT8646SIV#WPBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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