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Analog Devices Inc. LT8646SEV#WPBF
- Part No.:
- LT8646SEV#WPBF
- Manufacturer:
- Analog Devices Inc.
- Package:
- 32-TFQFN Exposed Pad
- Datasheet:
-
LT8646SEV#WPBF.pdf
- Description:
- IC REG BUCK ADJ 8A 32LQFN
- Quantity:
- Payment:
- Shipping:
Inventory:514
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Product details
Overview
LT8646SEV#WPBF from Analog Devices is an automotive-grade 65V input, 8A synchronous step-down Silent Switcher 2 regulator with external compensation, 2.5µA quiescent current in Burst Mode, 40ns minimum on-time, and integrated bypass capacitors for ultra-low EMI. It operates from 3.4V to 65V input, delivers up to 8A output at adjustable voltage, and targets high-reliability automotive power supplies.
For engineers reviewing the LT8646SEV#WPBF datasheet, LT8646SEV#WPBF pinout, LT8646SEV#WPBF application, or LT8646SEV#WPBF equivalent, key selection criteria include its AEC-Q100 qualification, external VC-loop compensation for fast transient response and current sharing, spread spectrum EMI reduction, and 6mm × 4mm LQFN thermal performance with exposed GND pads.
Technical Context
The LT8646SEV#WPBF implements peak current mode control with a dedicated VC error amplifier output enabling user-configurable loop compensation via external RC network-critical for optimizing stability and transient response across wide load and line variations. Its second-generation Silent Switcher 2 architecture integrates internal VIN, BST, and INTVCC bypass capacitors to minimize high-di/dt loop area and eliminate layout sensitivity for radiated EMI compliance.
It supports four operating modes via SYNC/MODE pin: Burst Mode (ultralow IQ), pulse-skipping (full-frequency down to light loads), spread spectrum (±24% frequency dithering), and external synchronization (200kHz–2.2MHz). The 40ns minimum on-time enables high step-down ratios (e.g., 48V→3.3V) at 2MHz switching, while low dropout (60mV @ 1A) ensures regulation under high-current, low-VIN conditions.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 3.4V to 65V - supports wide automotive battery transients including cold-crank (4.5V) and load-dump (60V). |
| Output Current | 8A continuous - sufficient for powering ADAS processors, radar modules, or infotainment SoCs from single-stage conversion. |
| Quiescent Current (Burst Mode) | 2.5µA @ 12VIN→3.3VOUT - enables >1-year battery standby in always-on automotive modules. |
| Switching Frequency Range | 200kHz to 2.2MHz - programmable via RT resistor; allows optimization of size (high-freq) vs. efficiency (low-freq). |
| Minimum On-Time | 40ns - enables 48V→3.3V conversion at 2MHz without pulse skipping, reducing output filter size. |
| EMI Performance | CISPR 25 Class 5 compliant - achieves <10dBµV/m margin in radiated emissions with standard PCB layout, no added shielding. |
| Thermal Resistance (θJC) | 4.4°C/W - low junction-to-case resistance via 6mm×4mm LQFN exposed pad, enabling 8A operation without forced air. |
Pinout & Package
LT8646SEV#WPBF is housed in a 32-lead 6mm × 4mm × 0.94mm LQFN package with six exposed GND pads (Pins 33–38) requiring soldering to PCB for optimal thermal and EMI performance. Pin count and footprint match industry-standard QFN packages.
| 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 inductance; must be locally bypassed with ≥4.7µF ceramic capacitor. |
| GND (Pins 8,9,10,17,18,19,33–38) | Power and signal reference ground | Exposure of Pins 33–38 as thermal pad mandates direct solder connection to inner/outer GND planes for θJC = 4.4°C/W. |
| SW (Pins 12,13,14,15,16) | Switch node output | Five paralleled SW pins minimize trace inductance and EMI; requires compact routing to inductor and BST capacitor. |
| VC (Pin 30) | Error amplifier output | External compensation node: RC network from VC to GND sets loop bandwidth and phase margin for current sharing or fast transients. |
| 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 VOUT ramp rate; supports power sequencing with other rails. |
| PG (Pin 31) | Power good open-drain flag | Asserts high when FB is within ±8% of target and no faults (UVLO, thermal, EN/UV low); pulls low during startup/faults. |
Key Features
| Feature | Design Value |
|---|---|
| Silent Switcher 2 architecture | Integrated VIN/BST/INTVCC bypass capacitors eliminate layout-dependent EMI peaks and enable CISPR 25 Class 5 compliance on 2-layer PCBs. |
| External VC compensation | Enables precise loop tuning for multi-phase current sharing and <10µs recovery from 2A→4A load transients with <150mV undershoot. |
| AEC-Q100 Grade 1 qualification | Rated for –40°C to +125°C junction temperature with full parametric validation-suitable for engine bay and ADAS ECU deployments. |
| Spread spectrum modulation | ±24% frequency dithering reduces peak radiated emissions by up to 10dBµV/m without sacrificing efficiency or output ripple. |
| Low dropout operation | 60mV dropout at 1A enables stable 3.3V output even during 4.5V cold-crank events, avoiding brownout resets. |
Applications
| Automotive ADAS Power Supply | Industrial 24V-to-5V Conversion |
|---|---|
Use Scenario: Powering 77GHz radar transceivers requiring clean, low-noise 5V/3A supply in compact front-bumper module. IC Role / Device Role / Timing Role: Primary buck converter delivering regulated 5V with <10mVP-P ripple and <100ns transient response to RF ICs. Use Value: Silent Switcher 2 EMI suppression eliminates need for ferrite beads or metal shields, reducing BOM cost and board area by 35%. |
Use Scenario: Converting 24V factory bus to 5V for PLC I/O modules operating in electrically noisy environments. IC Role / Device Role / Timing Role: High-efficiency, wide-input buck regulator with robust UVLO hysteresis and thermal shutdown. Use Value: 94% efficiency at 2MHz/24V→5V enables convection-cooled design; AEC-Q100 reliability extends field life beyond 15 years. |
| GSM Base Station Bias Supply | Automotive Infotainment Core Rail |
Use Scenario: Generating 3.3V/6A bias for cellular modem RF front-end in telematics control units. IC Role / Device Role / Timing Role: High-current, low-IQ buck converter supporting burst-mode sleep states during idle periods. Use Value: 2.5µA quiescent current extends backup battery life to >3 months; 40ns min-on-time supports 48V→3.3V at 2MHz. |
Use Scenario: Providing 1.1V/8A core voltage for automotive-grade application processors in digital clusters. IC Role / Device Role / Timing Role: Precision-adjustable buck regulator with TR/SS tracking for controlled power-up sequencing with DDR memory. Use Value: External VC compensation ensures <5% output deviation during 0→8A load steps; PG flag synchronizes SoC reset release. |
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 | Internal compensation; 1.7µA Burst Mode IQ; no VC pin; identical pinout and package. | Better suited for fixed-output, space-constrained designs where loop tuning isn't required. | Select LT8645SEV#WPBF when simplicity and lowest quiescent current outweigh need for current sharing or aggressive transient response. |
| MPQ4436-AEC1 | 40V max input; 6A output; 17µA IQ; no spread spectrum; QFN-20 package (smaller, fewer pins). | Limited to lower-voltage automotive systems (e.g., body control); lacks Silent Switcher EMI advantages. | Choose MPQ4436-AEC1 only for cost-sensitive, lower-power (<6A) applications where 65V capability and Class 5 EMI aren't mandatory. |
Compared with LT8645SEV#WPBF, the LT8646SEV#WPBF trades slightly higher light-load IQ for design flexibility via VC compensation and faster transient immunity; versus MPQ4436-AEC1, it delivers superior high-voltage robustness, EMI performance, and thermal capability at the cost of larger footprint and higher unit price.
Availability
LT8646SEV#WPBF is available at Aetrix Electronics and suitable for automotive ADAS systems, industrial 24V power supplies, and GSM base station biasing requiring stable component supply, AEC-Q100 assurance, and long-term lifecycle support.
Supply support for LT8646SEV#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 precision instrumentation, communications, and automotive markets since 1965.
The LT8646SEV#WPBF belongs to Analog Devices' Silent Switcher 2 DC/DC regulator family, engineered specifically for automotive and industrial applications demanding ultra-low EMI, high efficiency across wide input ranges, and AEC-Q100 reliability without external filtering.
FAQ
What is the maximum input voltage rating for the LT8646SEV#WPBF?
The LT8646SEV#WPBF has an absolute maximum input voltage rating of 65V on the VIN pins, with guaranteed operation from 3.4V to 65V. This enables robust handling of automotive load-dump transients (up to 60V per ISO 7637-2) and industrial 48V bus variations without external protection circuitry.
Does the LT8646SEV#WPBF require external compensation components?
Yes, the LT8646SEV#WPBF features an exposed VC pin (Pin 30) that requires an external RC network connected from VC to GND to set loop bandwidth and phase margin. This enables precise tuning for current sharing in parallel configurations or optimized transient response-unlike the internally compensated LT8645SEV#WPBF.
How does the LT8646SEV#WPBF achieve CISPR 25 Class 5 EMI compliance?
The LT8646SEV#WPBF achieves CISPR 25 Class 5 compliance through its Silent Switcher 2 architecture: integrated VIN, BST, and INTVCC bypass capacitors minimize high-di/dt loop area, while symmetrical internal layout and balanced SW node routing cancel magnetic fields. No external EMI filters are needed on standard 2-layer PCBs.
What is the purpose of the exposed thermal pads (Pins 33–38) on the LT8646SEV#WPBF?
The exposed thermal pads (Pins 33–38) on the LT8646SEV#WPBF are GND-connected copper pads designed for direct soldering to the PCB's internal or bottom-side ground plane. This provides a low-thermal-resistance path (θJC = 4.4°C/W) to dissipate heat from the 8A power stage, enabling full-load operation without heatsinks or forced airflow.
Can the LT8646SEV#WPBF synchronize to an external clock source?
Yes, the LT8646SEV#WPBF can synchronize to an external clock via the SYNC/MODE pin (Pin 28). When driven with a TTL/CMOS clock signal between 200kHz and 2.2MHz, the device locks its internal oscillator and operates in pulse-skipping mode-enabling deterministic switching and reduced beat frequencies in multi-rail systems.
LT8646SEV#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)
LT8646SEV#WPBF FAQ
1.How can I place an order for LT8646SEV#WPBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LT8646SEV#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 LT8646SEV#WPBF reliable?
The price and inventory of LT8646SEV#WPBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LT8646SEV#WPBF is usually 5 days.
3.What payment methods are accepted for LT8646SEV#WPBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LT8646SEV#WPBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LT8646SEV#WPBF?
LT8646SEV#WPBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LT8646SEV#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 LT8646SEV#WPBF?
For technical support, including LT8646SEV#WPBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LT8646SEV#WPBF requirements.
6.How does Aetrix verify that LT8646SEV#WPBF is sourced from the original manufacturer or authorized distributors?
All LT8646SEV#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 LT8646SEV#WPBF meets industry standards.
7.What is the process for return or replacement of LT8646SEV#WPBF?
All LT8646SEV#WPBF units undergo pre-shipment inspection (PSI). If there is an issue with LT8646SEV#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 LT8646SEV#WPBF part is unused and in its original packaging.
Return procedure for LT8646SEV#WPBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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