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Analog Devices Inc. LT8641EUDC#PBF
- Part No.:
- LT8641EUDC#PBF
- Manufacturer:
- Analog Devices Inc.
- Package:
- 20-WFQFN, 18 Leads, Exposed Pad
- Datasheet:
-
LT8641EUDC#PBF.pdf
- Description:
- IC REG BUCK ADJ 3.5A 20QFN
- Quantity:
- Payment:
- Shipping:
Inventory:9,666
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Product details
Overview
LT8641EUDC#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 18-lead 3mm × 4mm 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 LT8641EUDC#PBF datasheet, LT8641EUDC#PBF pinout, LT8641EUDC#PBF application, or LT8641EUDC#PBF equivalent, key selection criteria include ultralow IQ under light load, high-frequency operation up to 3MHz, AEC-Q100 qualification (E-grade), fast transient response with <10mVP-P ripple, and robust overload tolerance with saturated inductor handling.
Technical Context
The LT8641EUDC#PBF implements peak current mode control with an internal 0.8V reference and programmable oscillator (200kHz–3MHz via RT resistor). Its Silent Switcher architecture uses symmetrical layout and integrated BST capacitor to suppress common-mode EMI, validated per CISPR 25 Class 5 radiated/ conducted limits.
It features four operating modes selected via SYNC/MODE pin: Burst Mode (2.5µA IQ), pulse-skipping, spread-spectrum modulation (±22% frequency dither), and external clock synchronization. The EN/UV pin provides adjustable undervoltage lockout, while TR/SS enables soft-start and output voltage tracking with 1.9µA internal pull-up current.
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, 48V systems. |
| Continuous Output Current | 3.5A - sufficient for powering FPGA cores, microcontrollers, and sensor subsystems without external heatsinking. |
| Quiescent Current | 2.5µA at 12VIN→3.3VOUT in regulation - enables >10-year battery life in always-on IoT sensors. |
| Switching Frequency Range | 200kHz to 3MHz - allows compact magnetics (e.g., 1.5µH at 3MHz) and avoids AM radio band interference. |
| Minimum On-Time | 35ns - enables high VIN-to-low VOUT conversion (e.g., 48V→3.3V at 2MHz) without pulse skipping. |
| Output Voltage Ripple | <10mVP-P - ensures stable supply for noise-sensitive analog circuits and high-speed ADCs. |
| Thermal Performance | θJA = 40°C/W - enables full 3.5A output at +85°C ambient with minimal PCB copper area. |
Pinout & Package
Package: 18-lead (3mm × 4mm) plastic QFN with exposed SW pads (pins 21, 22); θJC(PAD) = 12°C/W; RoHS-compliant lead-free finish (PBF).
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| BIAS (1) | Internal regulator bias supply | Reduces VIN current draw when tied to ≥3.3V output; improves light-load efficiency by sourcing INTVCC from BIAS instead of VIN. |
| INTVCC (2) | Internal 3.4V regulator bypass | Must be decoupled with ≥1µF ceramic cap; powers control logic and gate drivers; not for external loading. |
| BST (3) | Bootstrap capacitor node | Requires 0.1µF ceramic cap between BST and SW to drive high-side NMOS gate above VIN. |
| VIN1 (4), VIN2 (13) | Dual input power rails | Each requires dedicated 1µF local bypass cap to GND1/GND2; reduces high-di/dt loop inductance for EMI suppression. |
| GND1 (6,7), GND2 (10,11) | Power switch return paths | Must be tied together and connected to low-impedance ground plane; forms critical high-current return loops with input caps. |
| SW (8,9,21,22) | Switch node | Exposed pad (21,22) must be soldered to SW trace for thermal performance; all SW pins tied together to inductor and BST cap. |
| EN/UV (14) | Enable and input UVLO control | Hysteretic threshold (0.95V–1.07V) allows resistor-divider programming of input shutdown voltage. |
| RT (15) | Oscillator frequency set | Resistor to GND programs switching frequency (e.g., 60.4kΩ = ~700kHz); sets minimum on-time scaling. |
| TR/SS (16) | Soft-start and tracking | 1.9µA internal current charges external cap to control output ramp rate; enables power sequencing with other rails. |
| SYNC/MODE (17) | Operating mode select | Ground = Burst Mode; float = pulse-skipping; INTVCC = spread spectrum; external clock = sync mode. |
| GND (18) | System ground reference | Connects to system ground plane; separate from GND1/GND2 but must be low-impedance bonded. |
| PG (19) | Power good indicator | Open-drain output asserts high when FB is within ±7.5% of 0.8V reference and no fault conditions exist. |
| FB (20) | Feedback voltage sense | Regulates to 0.804V typical; requires resistive divider and 4.7pF–22pF phase-lead capacitor for stability. |
Key Features
| Feature | Design Value |
|---|---|
| Silent Switcher® EMI reduction | Meets CISPR 25 Class 5 radiated/conducted limits without external filters-reduces layout iteration time and BOM cost. |
| Ultralow 2.5µA quiescent current | Enables >10-year battery life in always-on applications such as telematics and remote sensors without compromising regulation. |
| 35ns minimum on-time | Supports direct 48V-to-3.3V or 24V-to-1.2V conversion at 2MHz, eliminating intermediate stages and improving system efficiency. |
| Spread-spectrum frequency modulation | ±22% triangular dither reduces peak EMI by >10dB across 150kHz–108MHz-critical for automotive infotainment compliance. |
| AEC-Q100 Grade E qualification | Rated for –40°C to +125°C junction temperature with production flow assurance-suitable for engine bay and ADAS power rails. |
| Robust overload protection | Tolerates inductor saturation during overloads; bottom switch current limit (4.8A typ) prevents thermal runaway under short-circuit conditions. |
Applications
| Automotive Infotainment Power | Industrial PLC I/O Module |
|---|---|
Use Scenario: Powering SoC, DDR memory, and display interface in head-unit systems with 12V/24V battery input and strict CISPR 25 EMI limits. IC Role / Device Role / Timing Role: Primary 5V/3.3V buck converter delivering 3.5A with spread-spectrum mode enabled to pass Class 5 radiated emission tests. Use Value: Eliminates need for external EMI filters and ferrite beads, reducing board area by 25% and component count by 6 parts versus legacy solutions. | Use Scenario: Providing isolated 5V rail for digital I/O expansion cards in modular PLC chassis with wide-input 18–60VDC field supply. IC Role / Device Role / Timing Role: High-reliability step-down regulator with AEC-Q100 qualification and 65V absolute max rating for surge immunity. Use Value: Maintains regulation during 40V transients per IEC 61000-4-5; 2.5µA IQ extends backup battery runtime during brownout events. |
| Telecom Remote Radio Unit | Medical Point-of-Care Monitor |
Use Scenario: Generating 3.3V/2A supply for FPGA-based signal processing in outdoor 48V-powered RRUs with limited thermal dissipation. IC Role / Device Role / Timing Role: High-frequency (2MHz) buck converter using 1.5µH inductor to minimize size and weight in compact RF enclosure. Use Value: Achieves 94% efficiency at 2MHz (48VIN→3.3VOUT), reducing thermal load by 1.8W versus 500kHz alternatives. | Use Scenario: Powering low-noise analog front-end and ARM Cortex-M7 MCU in portable diagnostic devices requiring ultraquiet 5V rail. IC Role / Device Role / Timing Role: Low-ripple (<10mVP-P) regulator operating in Burst Mode to preserve battery life during standby. Use Value: Delivers clean power with <10mVP-P ripple at full load-meets IEC 60601-1 EMC immunity requirements without additional LDO post-regulation. |
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#PBF | Higher 8A output current, same 65V input, identical pinout and feature set except higher current capability and larger thermal pad. | Required where >3.5A continuous load exists; shares same PCB footprint but needs upgraded thermal design. | Select LT8645SIV#PBF only if peak load exceeds 3.5A; otherwise LT8641EUDC#PBF offers lower cost and smaller solution size. |
| TPS546B24RVFT | 60V input, 6A output, 2.5µA IQ, but lacks spread-spectrum and Silent Switcher; uses different pinout and requires external bootstrap diode. | Lower EMI performance; not AEC-Q100 qualified; suitable for non-automotive industrial use where EMI is less constrained. | Choose TPS546B24RVFT only if TI ecosystem preference dominates; LT8641EUDC#PBF provides superior EMI and automotive qualification. |
Compared with LT8645SIV#PBF and TPS546B24RVFT, the LT8641EUDC#PBF uniquely balances 3.5A capability, ultralow EMI, AEC-Q100 qualification, and minimal 3mm×4mm footprint-making it optimal for space-constrained automotive and industrial converters where 3.5A suffices.
Availability
LT8641EUDC#PBF is available at Aetrix Electronics and suitable for automotive infotainment systems, industrial PLC power modules, and telecom remote radio units requiring stable component supply, long-term lifecycle support, and AEC-Q100-compliant performance.
Supply support for LT8641EUDC#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, Inc. is a global leader in high-performance analog, mixed-signal, and digital signal processing semiconductors, serving precision instrumentation, communications, and industrial markets.
The LT8641EUDC#PBF belongs to the Silent Switcher® monolithic buck regulator product line, designed specifically for high-efficiency, low-EMI power conversion in automotive, industrial, and medical applications demanding reliability and regulatory compliance.
FAQ
What is the maximum junction temperature rating for the LT8641EUDC#PBF?
The LT8641EUDC#PBF is rated for –40°C to +125°C operating junction temperature. This grade (E) is guaranteed over the full range per datasheet Rev. C, with thermal shutdown activating above 150°C to protect against sustained overload conditions. The device's θJA of 40°C/W enables full 3.5A output at +85°C ambient with standard 2-layer PCB layout.
Does the LT8641EUDC#PBF require an external bootstrap diode?
No, the LT8641EUDC#PBF does not require an external bootstrap diode. Its integrated bootstrap circuit uses an internal charge pump and the BST pin connects directly to a 0.1µF ceramic capacitor between BST and SW. This eliminates discrete diode losses and layout complexity while maintaining reliable high-side gate drive across the full input range.
Can the LT8641EUDC#PBF synchronize to an external clock source?
Yes, the LT8641EUDC#PBF can synchronize to an external clock via the SYNC/MODE pin. When driven with a TTL/CMOS-compatible clock signal (200kHz–3MHz), the device operates in pulse-skipping mode aligned to the external frequency-enabling deterministic switching in noise-sensitive systems and multi-rail EMI cancellation.
How is the output voltage programmed on the LT8641EUDC#PBF?
The output voltage is programmed using a resistive divider from VOUT to FB and GND. The LT8641EUDC#PBF regulates the FB pin to 0.804V (typical), so VOUT = 0.804V × (1 + R1/R2). A 4.7pF–22pF capacitor between FB and VOUT provides phase lead compensation for stability across all loads and input voltages.
Is the LT8641EUDC#PBF pin-compatible with other members of the LT864x family?
Yes, the LT8641EUDC#PBF shares identical pinout and package (18-lead 3mm×4mm QFN) with LT8640S, LT8642S, LT8643, and LT8645S. This enables drop-in replacement for design reuse-though current ratings, thermal performance, and certain features (e.g., spread-spectrum enable) differ across variants and must be verified per application requirements.
LT8641EUDC#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)
LT8641EUDC#PBF FAQ
1.How can I place an order for LT8641EUDC#PBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LT8641EUDC#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 LT8641EUDC#PBF reliable?
The price and inventory of LT8641EUDC#PBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LT8641EUDC#PBF is usually 5 days.
3.What payment methods are accepted for LT8641EUDC#PBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LT8641EUDC#PBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LT8641EUDC#PBF?
LT8641EUDC#PBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LT8641EUDC#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 LT8641EUDC#PBF?
For technical support, including LT8641EUDC#PBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LT8641EUDC#PBF requirements.
6.How does Aetrix verify that LT8641EUDC#PBF is sourced from the original manufacturer or authorized distributors?
All LT8641EUDC#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 LT8641EUDC#PBF meets industry standards.
7.What is the process for return or replacement of LT8641EUDC#PBF?
All LT8641EUDC#PBF units undergo pre-shipment inspection (PSI). If there is an issue with LT8641EUDC#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 LT8641EUDC#PBF part is unused and in its original packaging.
Return procedure for LT8641EUDC#PBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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