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Analog Devices Inc. LT8641IUDC#PBF
- Part No.:
- LT8641IUDC#PBF
- Manufacturer:
- Analog Devices Inc.
- Package:
- 20-WFQFN, 18 Leads, Exposed Pad
- Datasheet:
-
LT8641IUDC#PBF.pdf
- Description:
- IC REG BUCK ADJ 3.5A 20QFN
- Quantity:
- Payment:
- Shipping:
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Product details
Overview
LT8641IUDC#PBF from Analog Devices is a 65V input, 3.5A synchronous step-down DC/DC regulator with Silent Switcher architecture, 2.5µA quiescent current in regulation, 35ns minimum on-time, and integrated power switches in a 3mm × 4mm 18-lead QFN package. It delivers up to 95% efficiency at 1MHz (12VIN→5VOUT) and supports spread spectrum EMI reduction for automotive and industrial power supplies.
For engineers reviewing the LT8641IUDC#PBF datasheet, LT8641IUDC#PBF pinout, LT8641IUDC#PBF application, or LT8641IUDC#PBF equivalent, key selection considerations include ultralow IQ operation under light loads, AEC-Q100 qualification for automotive use, fast transient response with <10mVP-P ripple, and programmable switching frequency from 200kHz to 3MHz via RT resistor.
Technical Context
The LT8641IUDC#PBF implements peak current mode control with internal 0.8V reference and frequency foldback during startup or overload. Its Silent Switcher architecture uses symmetrical layout and integrated bypass paths to suppress common-mode EMI without external filters.
It features four SYNC/MODE-configurable operating states: Burst Mode (2.5µA IQ), pulse-skipping, spread spectrum modulation (±22% frequency dither), and external clock synchronization. The BIAS pin enables efficiency optimization by sourcing INTVCC from VOUT when ≥3.3V.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 3V to 65V - supports wide-range industrial and automotive battery inputs including 12V, 24V, 36V, and 48V systems. |
| Continuous Output Current | 3.5A - sufficient for powering microcontrollers, FPGAs, sensors, and communication ICs in compact designs. |
| Quiescent Current (IQ) | 2.5µA at 12VIN→3.3VOUT in regulation - enables multi-year battery life in always-on IoT and telematics applications. |
| Minimum Switch On-Time | 35ns - allows high-frequency, high-step-down ratio conversion (e.g., 48V→3.3V at 2MHz) without pulse skipping. |
| Feedback Reference Voltage | 0.804V (typ) - precise regulation tolerance enables accurate output setting with standard resistor dividers. |
| Switching Frequency Range | 200kHz to 3MHz - adjustable via RT pin; higher frequencies reduce inductor size and improve transient response. |
| EMI Performance | CISPR 25 Class 5 compliant in spread spectrum mode - eliminates need for external EMI filters in automotive infotainment and ADAS modules. |
| Thermal Rating | –40°C to +125°C junction - qualified per AEC-Q100 Grade I, suitable for under-hood and industrial control environments. |
Pinout & Package
Package: 18-lead (3mm × 4mm) plastic QFN with exposed SW pads (pins 21, 22). Exposed pads must be soldered to SW trace for thermal performance; pins 5 and 12 are omitted per JEDEC outline.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| VIN1, VIN2 | Input Power Inputs | Dual VIN pins reduce high-frequency input loop inductance; require separate 1µF ceramic caps to GND1/GND2 for EMI suppression. |
| GND1, GND2 | Power Ground Returns | Independent ground paths for bottom switch return; must be tied together and connected to low-impedance ground plane. |
| SW (pins 8, 9, 21, 22) | Switch Node | High dv/dt node connecting internal MOSFETs to inductor and BST capacitor; exposed pads enhance thermal conduction to PCB. |
| BST | Bootstrap Supply | Drives top MOSFET gate above VIN; requires 0.1µF ceramic cap placed adjacent to pin for reliable high-side switching. |
| EN/UV | Enable / Input Undervoltage Lockout | Hysteretic threshold (1.01V rise / 0.96V fall); resistor divider from VIN sets custom UVLO point for system brownout protection. |
| SYNC/MODE | Operating Mode Control | Selects Burst Mode (ground), pulse-skipping (float), spread spectrum (3–4V), or external sync (clock input). |
| TR/SS | Soft-Start / Tracking | 1.9µA internal current source charges external capacitor to control output ramp rate; supports voltage tracking of other rails. |
| FB | Feedback Input | Regulates to 0.804V reference; connects to resistor divider tap; 4.7–22pF phase-lead capacitor improves stability. |
| PG | Power Good Output | Open-drain signal asserts high when FB is within ±7.5% of target; valid above 3V VIN regardless of EN state. |
Key Features
| Feature | Design Value |
|---|---|
| Silent Switcher Architecture | Integrated dual-input/dual-ground layout and internal bypass paths reduce radiated/conducted EMI by >30dB vs conventional buck regulators. |
| Ultralow Quiescent Current | 2.5µA IQ in Burst Mode maintains regulation at zero load - critical for battery-powered automotive telematics and remote sensors. |
| Spread Spectrum Modulation | ±22% triangular frequency dither centered on programmed fSW - lowers peak EMI emissions to meet CISPR 25 Class 5 without shielding. |
| Fast Minimum On-Time | 35ns enables direct 48V-to-3.3V conversion at 2MHz - reduces solution size by allowing smaller inductors (e.g., 1.5µH instead of 4.7µH). |
| AEC-Q100 Grade I Qualification | Qualified for –40°C to +125°C operation with full parametric testing - approved for automotive powertrain, body electronics, and ADAS subsystems. |
| Robust Overload Tolerance | Safely handles inductor saturation during overload; bottom switch current limit (5.8A typ) prevents thermal runaway without external protection. |
Applications
| Automotive Infotainment Power | Industrial PLC I/O Module |
|---|---|
Use Scenario: Powering 5V/3.5A SoC, display controller, and USB hub in head unit with 12V/24V battery input and strict EMI limits. IC Role / Device Role / Timing Role: Primary synchronous buck regulator providing clean, low-noise 5V rail with spread spectrum EMI suppression. Use Value: Meets CISPR 25 Class 5 radiated emission limits without ferrite beads or metal shielding, reducing BOM cost and board area. |
Use Scenario: Generating isolated 3.3V/2A supply for ARM-based controller and analog front-end in DIN-rail mounted PLC. IC Role / Device Role / Timing Role: High-efficiency, wide-input buck converter delivering stable output across 18–36V AC/DC input variations. Use Value: 94% efficiency at 2MHz (12VIN→3.3VOUT) enables convection-only cooling in sealed enclosures with no fan required. |
| GSM Base Station RF Power Amplifier Bias | Medical Portable Diagnostic Device |
Use Scenario: Providing 5V/3A bias supply to GaN RF power amplifier stages in small-cell base stations with 48V backplane input. IC Role / Device Role / Timing Role: High-step-down buck regulator with 35ns min on-time enabling 48V→5V conversion at 2MHz. Use Value: Eliminates need for intermediate 12V bus, reducing component count and improving overall system efficiency by 8%. |
Use Scenario: Powering FPGA, ADC, and wireless transceiver in handheld ultrasound or glucose monitor with coin-cell or Li-ion battery. IC Role / Device Role / Timing Role: Ultralow-IQ buck regulator maintaining 3.3V output during multi-week standby with sub-µA sleep current. Use Value: 2.5µA quiescent current extends single-charge battery life to >3 years in always-on monitoring mode. |
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#PBF | Same 65V/3.5A rating but lower IQ (2.5µA vs 2.5µA), identical pinout, and added low-EMI enhancements including improved spread spectrum linearity. | Targeted for next-gen automotive radar and camera modules requiring tighter EMI margins than Class 5. | Prefer LT8640SIV#PBF if new design requires enhanced EMI robustness and future-proofing against stricter OEM requirements. |
| MPQ4433AGL-AEC1-Z | 40V max input, 3.5A, 17µA IQ in forced PWM mode, QFN-16 package, AEC-Q100 qualified but lacks spread spectrum or Silent Switcher EMI suppression. | Suitable for cost-sensitive 12V/24V systems where EMI filtering is handled externally or relaxed. | Choose MPQ4433AGL-AEC1-Z only when input voltage never exceeds 40V and EMI compliance can be achieved via board-level filtering. |
Compared with LT8641IUDC#PBF, LT8640SIV#PBF offers marginally better EMI performance at identical efficiency and footprint, while MPQ4433AGL-AEC1-Z trades EMI capability and input range for lower unit cost in non-critical applications.
Availability
LT8641IUDC#PBF is available at Aetrix Electronics and suitable for automotive infotainment, industrial PLCs, GSM RF bias, and portable medical devices requiring stable component supply, long-term lifecycle support, and AEC-Q100-compliant performance.
Supply support for LT8641IUDC#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 industrial, automotive, communications, and healthcare markets.
The LT8641IUDC#PBF belongs to the Silent Switcher® family of high-efficiency, low-EMI DC/DC regulators designed specifically for demanding automotive and industrial applications where EMI, thermal, and reliability constraints are critical.
FAQ
What is the maximum input voltage rating for the LT8641IUDC#PBF?
The LT8641IUDC#PBF has an absolute maximum input voltage rating of 65V on VIN1 and VIN2 pins. Its operational input range is specified from 3V to 65V, making it suitable for 48V automotive systems, industrial 24V/36V rails, and wide-range off-line auxiliary supplies. Exceeding 65V risks permanent damage per Absolute Maximum Ratings.
Does the LT8641IUDC#PBF support external frequency synchronization?
Yes, the LT8641IUDC#PBF supports external synchronization via the SYNC/MODE pin. When driven with a clean CMOS clock signal between 200kHz and 3MHz, the device locks its internal oscillator and operates in pulse-skipping mode aligned to the external clock edge - essential for noise-sensitive systems like audio amplifiers or high-speed data converters.
How does the LT8641IUDC#PBF achieve ultralow quiescent current?
The LT8641IUDC#PBF achieves 2.5µA quiescent current in Burst Mode by completely disabling gate drivers, error amplifier, and oscillator between energy bursts while maintaining regulation via output capacitor hold-up. This is enabled by grounding the SYNC/MODE pin and is verified across –40°C to +125°C for automotive-grade reliability.
Is the LT8641IUDC#PBF pin-compatible with other members of the LT864x family?
Yes, the LT8641IUDC#PBF shares identical 18-lead QFN (UDC) package, pinout, and footprint with LT8640, LT8640S, and LT8642 variants. However, functional differences exist - e.g., LT8640S adds enhanced spread spectrum linearity, and LT8642 increases output current to 5A - so electrical validation is required before substitution.
What thermal performance can be expected from the LT8641IUDC#PBF in a typical 4-layer PCB layout?
In a standard 4-layer PCB with 2oz copper, 6 thermal vias under the exposed SW pad, and 25mm² GND pour connected to GND1/GND2, the LT8641IUDC#PBF achieves θJA ≈ 40°C/W. At 3.5A/5V output with 12VIN and 1MHz switching, junction temperature rise is typically ≤45°C above ambient - well within the –40°C to +125°C operating range.
LT8641IUDC#PBF Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- Silent Switcher®1
- Package/Case:
- 20-WFQFN, 18 Leads, Exposed Pad
- Packaging:
- Tube
- 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):
- 0.8V
- Voltage - Output (Max):
- 64.35V
- Current - Output:
- 3.5A
- Frequency - Switching:
- 210kHz ~ 2MHz
- Synchronous Rectifier:
- Yes
- Operating Temperature:
- -40°C ~ 125°C (TJ)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 20-QFN (3x4)
LT8641IUDC#PBF FAQ
1.How can I place an order for LT8641IUDC#PBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LT8641IUDC#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 LT8641IUDC#PBF reliable?
The price and inventory of LT8641IUDC#PBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LT8641IUDC#PBF is usually 5 days.
3.What payment methods are accepted for LT8641IUDC#PBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LT8641IUDC#PBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LT8641IUDC#PBF?
LT8641IUDC#PBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LT8641IUDC#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 LT8641IUDC#PBF?
For technical support, including LT8641IUDC#PBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LT8641IUDC#PBF requirements.
6.How does Aetrix verify that LT8641IUDC#PBF is sourced from the original manufacturer or authorized distributors?
All LT8641IUDC#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 LT8641IUDC#PBF meets industry standards.
7.What is the process for return or replacement of LT8641IUDC#PBF?
All LT8641IUDC#PBF units undergo pre-shipment inspection (PSI). If there is an issue with LT8641IUDC#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 LT8641IUDC#PBF part is unused and in its original packaging.
Return procedure for LT8641IUDC#PBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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