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Analog Devices Inc. LT8646SEV#PBF
- Part No.:
- LT8646SEV#PBF
- Manufacturer:
- Analog Devices Inc.
- Package:
- 32-TFQFN Exposed Pad
- Datasheet:
-
LT8646SEV#PBF.pdf
- Description:
- IC REG BUCK ADJ 8A 32LQFN
- Quantity:
- Payment:
- Shipping:
Inventory:2,514
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Product details
Overview
LT8646SEV#PBF from Analog Devices is a 65V input, 8A synchronous step-down DC/DC regulator featuring Silent Switcher 2 architecture, external compensation (VC pin), 2.5µA quiescent current in Burst Mode, 40ns minimum on-time, and AEC-Q100 qualification for automotive power supplies.
For engineers reviewing the LT8646SEV#PBF datasheet, LT8646SEV#PBF pinout, LT8646SEV#PBF application, or LT8646SEV#PBF equivalent, this page delivers verified specifications, validated pin functions, confirmed automotive-grade thermal and EMI performance, and real-world transient response data for high-reliability 12V–48V to 3.3V/5V conversion.
Technical Context
The LT8646SEV#PBF implements peak current mode control with an externally compensated error amplifier (VC pin), enabling precise current sharing across parallel converters and fast load-transient response at up to 2.2MHz switching frequency. Its integrated bypass capacitors on VIN, BST, and INTVCC minimize high-frequency loop area to meet CISPR 25 Class 5 radiated EMI limits without external filters.
It supports four operating modes via the SYNC/MODE pin: Burst Mode (ultralow IQ), pulse-skipping (full-frequency down to light loads), spread-spectrum modulation (EMI reduction), and external clock synchronization. The 0.97V feedback reference and ±8% power-good window ensure accurate regulation across –40°C to 125°C junction temperature.
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 - delivers full rated current with thermal derating per θJC(PAD) = 4.4°C/W and exposed GND pad soldering. |
| Quiescent Current (Burst Mode) | 230µA (BIAS = 0V) or 120µA (BIAS = 5V) - enables >10-year battery life in always-on automotive modules. |
| Switching Frequency Range | 200kHz to 2.2MHz - adjustable via RT resistor; allows optimization of size vs. efficiency and avoids AM band interference. |
| Minimum On-Time | 40ns - enables high step-down ratios (e.g., 48V → 3.3V at 2MHz) without pulse skipping or instability. |
| Feedback Reference Voltage | 0.97V ±0.006V - tight tolerance ensures ±1% output accuracy over line, load, and temperature. |
| Power-Good Threshold | ±8% of VFB - provides reliable system sequencing with hysteresis to prevent chatter during startup or fault recovery. |
Pinout & Package
LT8646SEV#PBF uses a 32-lead 6mm × 4mm × 0.94mm LQFN package with six exposed GND pads (pins 33–38) requiring PCB soldering for thermal integrity and EMI suppression. Pin count and footprint match standard 6mm × 4mm QFN layouts.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| VIN (Pins 4,5,6,21,22,23) | Main input power supply | Multiple pins reduce IR drop and AC impedance; must be locally bypassed with ≥4.7µF ceramic capacitor. |
| GND (Pins 8,9,10,17,18,19,33–38) | Power and signal ground reference | Exposure pad soldering mandatory for thermal performance (θJC(PAD) = 4.4°C/W) and low-impedance return path. |
| SW (Pins 12,13,14,15,16) | Switch node connection | High-current, high-dV/dt node; requires minimal PCB copper area to suppress radiated EMI. |
| VC (Pin 30) | Error amplifier output | External compensation point: RC network sets loop bandwidth and phase margin for fast transient response. |
| EN/UV (Pin 25) | Enable and undervoltage lockout | Hysteretic threshold (1.01V rise / 0.965V fall) enables robust start-up under brownout conditions. |
| SYNC/MODE (Pin 28) | Operating mode selection | Configures Burst Mode (GND), pulse-skipping (float), spread spectrum (3–4V), or external sync (clock input). |
| TR/SS (Pin 29) | Soft-start and output tracking | 1.9µA internal pull-up enables capacitor-programmed slew rate; supports power-rail sequencing with other regulators. |
| PG (Pin 31) | Power-good open-drain flag | Asserts high only when VOUT is within ±8% of target and no faults (thermal, UVLO, EN low) are present. |
Key Features
| Feature | Design Value |
|---|---|
| Silent Switcher 2 Architecture | Integrated VIN/BST/INTVCC bypass capacitors eliminate layout sensitivity and enable <10mVP-P output ripple and CISPR 25 Class 5 compliance. |
| External Compensation (VC Pin) | Enables precise loop tuning for multi-phase current sharing and <50µs load transient recovery at 8A step change. |
| AEC-Q100 Grade | Qualified for automotive applications (-40°C to +125°C TJ); includes enhanced reliability testing and traceable manufacturing controls. |
| Ultralow Quiescent Current | 230µA (BIAS = 0V) in Burst Mode - extends battery runtime in telematics, ADAS sensors, and infotainment standby states. |
| Adjustable Spread Spectrum | 24% frequency modulation depth reduces peak EMI by >10dB without sacrificing efficiency or transient performance. |
Applications
| Automotive Infotainment Power | Industrial PLC I/O Module |
|---|---|
|
Use Scenario: Powering 5V/3.3V rails for SoC, display controller, and audio codec in head-unit systems with 12V/24V battery input. IC Role / Device Role / Timing Role: Primary synchronous buck regulator delivering 8A at 5V with soft-start sequencing and power-good signaling. Use Value: Meets CISPR 25 Class 5 radiated EMI limits without external filter components, reducing BOM cost and board space. |
Use Scenario: Generating isolated 5V logic supply for digital I/O expansion cards in programmable logic controllers operating from 24VDC field bus. IC Role / Device Role / Timing Role: High-efficiency, wide-input buck converter with adjustable frequency to avoid noise coupling into analog sensor channels. Use Value: 40ns minimum on-time enables stable 5V output from 24V input at 2MHz, minimizing inductor size while maintaining >94% efficiency. |
| GSM Base Station RF Power Amplifier Bias | Medical Imaging Sensor Supply |
|
Use Scenario: Providing clean, low-noise 5V bias for GaN RF power amplifiers in small-cell base stations powered from 48V telecom rectifiers. IC Role / Device Role / Timing Role: High-PSRR, low-ripple DC/DC stage preceding LDO post-regulation for PA bias voltage. Use Value: Output ripple <10mVP-P and ultralow EMI ensure minimal AM-to-PM distortion and adjacent-channel leakage ratio (ACLR) degradation. |
Use Scenario: Supplying 3.3V to low-power CMOS image sensors and ADC front-ends in portable ultrasound and X-ray detectors. IC Role / Device Role / Timing Role: Always-on, ultra-low-IQ power source supporting rapid wake-from-sleep imaging sequences. Use Value: 230µA Burst Mode IQ enables >10-year battery life in handheld devices while maintaining fast (<1ms) turn-on response. |
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#PBF | Internal compensation; 2.5µA IQ (vs. 230µA); identical pinout and package. | Better suited for fixed-output, single-rail applications where loop tuning is unnecessary. | Select LT8645SEV#PBF when simplified design, lowest possible standby current, and no current sharing are required. |
| MPQ4433AGL-AEC1-Z | 40V max input; 6A output; 17µA IQ; no spread spectrum; QFN-16 package. | Limited to lower-voltage automotive domains (e.g., body electronics); lacks EMI-hardened architecture. | Choose MPQ4433AGL-AEC1-Z only for cost-sensitive, non-critical 12V systems where CISPR 25 compliance is not mandated. |
Compared with LT8645SEV#PBF and MPQ4433AGL-AEC1-Z, the LT8646SEV#PBF uniquely combines 65V operation, external loop control, and certified EMI performance-making it the only option for high-reliability, high-EMI-margin automotive and industrial 48V-to-5V conversion.
Availability
LT8646SEV#PBF is available at Aetrix Electronics and suitable for automotive infotainment, industrial PLC power, and medical imaging sensor supply applications requiring stable component supply, long-term lifecycle support, and AEC-Q100-compliant sourcing.
Supply support for LT8646SEV#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 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#PBF belongs to the Silent Switcher 2 family of high-voltage, high-efficiency DC/DC regulators designed specifically for automotive and industrial applications demanding ultra-low EMI, wide input range, and AEC-Q100 reliability.
FAQ
What is the maximum input voltage rating for the LT8646SEV#PBF?
The LT8646SEV#PBF has an absolute maximum input voltage rating of 65V on the VIN pins. It operates continuously over a recommended input range of 3.4V to 65V, making it suitable for 48V industrial buses and automotive load-dump transients. Exceeding 65V may cause permanent damage per Absolute Maximum Ratings.
How does the VC pin on the LT8646SEV#PBF enable external compensation?
The VC pin on the LT8646SEV#PBF is the output of the internal error amplifier. Connecting an RC network from VC to GND sets the dominant pole and zero of the control loop, allowing precise tuning of phase margin and transient response-critical for current sharing in parallel configurations and fast 8A load steps.
Is the LT8646SEV#PBF qualified for automotive applications?
Yes, the LT8646SEV#PBF is AEC-Q100 qualified for automotive applications across the –40°C to +125°C junction temperature range. It undergoes rigorous stress testing and is manufactured under controlled processes to meet automotive reliability standards, as documented in Analog Devices' Automotive Reliability Reports.
What is the purpose of the SYNC/MODE pin on the LT8646SEV#PBF?
The SYNC/MODE pin on the LT8646SEV#PBF selects among four operating modes: Burst Mode (GND), pulse-skipping (floating), spread-spectrum modulation (3–4V), or external clock synchronization (AC-coupled clock). This flexibility allows optimization of efficiency, EMI, and system timing without changing hardware.
Can the LT8646SEV#PBF achieve <10mVP-P output ripple in a typical application?
Yes, the LT8646SEV#PBF achieves <10mVP-P output ripple in standard configurations due to its Silent Switcher 2 architecture-including integrated bypass capacitors and optimized internal current loops. Verified performance is documented in Figure 1 of the LT8645S/LT8646S datasheet Rev. E using a 100µF output capacitor and 4.7pF feedforward capacitor.
LT8646SEV#PBF 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:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 32-LQFN (6x4)
LT8646SEV#PBF FAQ
1.How can I place an order for LT8646SEV#PBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LT8646SEV#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 LT8646SEV#PBF reliable?
The price and inventory of LT8646SEV#PBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LT8646SEV#PBF is usually 5 days.
3.What payment methods are accepted for LT8646SEV#PBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LT8646SEV#PBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LT8646SEV#PBF?
LT8646SEV#PBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LT8646SEV#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 LT8646SEV#PBF?
For technical support, including LT8646SEV#PBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LT8646SEV#PBF requirements.
6.How does Aetrix verify that LT8646SEV#PBF is sourced from the original manufacturer or authorized distributors?
All LT8646SEV#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 LT8646SEV#PBF meets industry standards.
7.What is the process for return or replacement of LT8646SEV#PBF?
All LT8646SEV#PBF units undergo pre-shipment inspection (PSI). If there is an issue with LT8646SEV#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 LT8646SEV#PBF part is unused and in its original packaging.
Return procedure for LT8646SEV#PBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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