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Analog Devices Inc. LT8641HUDC#PBF
- Part No.:
- LT8641HUDC#PBF
- Manufacturer:
- Analog Devices Inc.
- Package:
- 20-WFQFN, 18 Leads, Exposed Pad
- Datasheet:
-
LT8641HUDC#PBF.pdf
- Description:
- IC REG BUCK ADJ 3.5A 20QFN
- Quantity:
- Payment:
- Shipping:
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Product details
Overview
LT8641HUDC#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 AEC-Q100 H-grade (–40°C to +150°C junction) qualification. It delivers up to 95% efficiency at 1MHz (12VIN→5VOUT) and supports spread spectrum EMI reduction.
For engineers reviewing the LT8641HUDC#PBF datasheet, LT8641HUDC#PBF pinout, LT8641HUDC#PBF application, or LT8641HUDC#PBF equivalent, key selection criteria include ultralow IQ for battery-backed systems, high-frequency operation up to 3MHz with fast transient response, automotive-grade thermal robustness, and integrated PG, soft-start, and tracking functionality.
Technical Context
The LT8641HUDC#PBF employs peak current mode control with internal top/bottom NMOS switches (105mΩ/55mΩ), programmable 200kHz–3MHz switching via RT resistor, and frequency foldback during low-VOUT conditions. Its Silent Switcher architecture uses symmetrical layout and integrated bypass paths to suppress common-mode EMI.
Operation modes are selected via SYNC/MODE pin: Burst Mode (2.5µA IQ), pulse-skipping, spread spectrum (±22% modulation), or external clock synchronization. The EN/UV pin provides adjustable undervoltage lockout, while TR/SS enables output voltage tracking and controlled soft-start ramp rate.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 3V to 65V - supports wide industrial and automotive supply rails including 24V, 36V, and 48V systems without pre-regulation. |
| Continuous Output Current | 3.5A - sufficient for powering microcontrollers, FPGAs, and sensor subsystems in compact designs. |
| Quiescent Current (IQ) | 2.5µA at 12VIN→3.3VOUT - enables multi-year battery life in always-on IoT and telematics applications. |
| Minimum Switch On-Time | 35ns - allows direct 48V-to-3.3V or 60V-to-5V conversion at 2MHz+ without duty-cycle limitation. |
| Feedback Reference Voltage | 0.804V (typ) - precise setpoint enabling accurate output regulation across temperature and load. |
| Switching Frequency Range | 200kHz to 3MHz - selectable via RT resistor; higher frequencies reduce inductor size and improve transient response. |
| EMI Performance | CISPR 25 Class 5 compliant with filter - meets stringent automotive radiated/conducted emission limits without added shielding. |
| Junction Temperature Range | –40°C to +150°C - qualified per AEC-Q100 Grade H for under-hood and powertrain applications. |
Pinout & Package
Package: 18-lead 3mm × 4mm plastic QFN (UDC) with exposed SW pads (pins 21, 22) requiring solder connection to PCB for thermal and electrical performance. Pin count and layout match JEDEC-standard 18-lead QFN footprint despite internal pin removal (pins 5, 12 omitted).
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| BIAS (1) | Internal regulator bias supply | Connect to VOUT (≥3.3V) to reduce VIN current draw and improve light-load efficiency. |
| INTVCC (2) | Internal 3.4V LDO output | Bypass with ≥1µF ceramic capacitor; powers control logic and gate drivers - not for external loading. |
| BST (3) | Bootstrap capacitor node | Requires 0.1µF ceramic capacitor between BST and SW to drive high-side NMOS gate above VIN. |
| VIN1 (4), VIN2 (13) | Main input power inputs | Each requires dedicated 1µF local ceramic bypass; dual-input structure minimizes high-di/dt loop area for EMI reduction. |
| GND1 (6,7), GND2 (10,11) | Power switch return paths | Must be tied together and connected to low-impedance ground plane; critical for thermal dissipation and EMI control. |
| SW (8,9,21,22) | Switch node outputs | Exposed pads (21,22) must be soldered to SW trace - primary thermal path and high-current return for both NMOS switches. |
| EN/UV (14) | Enable and input UVLO input | Hysteretic threshold (0.95V–1.07V) enables programmable input undervoltage shutdown using resistor divider. |
| RT (15) | Oscillator frequency programming | Resistor to GND sets fSW from 200kHz to 3MHz; tolerance directly impacts regulation accuracy and EMI profile. |
| TR/SS (16) | Soft-start and tracking control | 1.9µA internal current source enables capacitor-programmed output ramp rate; supports power sequencing with other rails. |
| SYNC/MODE (17) | Operating mode selection | Ground = Burst Mode; float = pulse-skipping; INTVCC = spread spectrum; external clock = sync - no external components needed. |
| GND (18) | System ground reference | Connect to system ground plane; complements GND1/GND2 for signal integrity and noise isolation. |
| PG (19) | Power good open-drain output | Asserts high when FB is within ±7.5% of 0.804V reference - used for system power sequencing and fault monitoring. |
| FB (20) | Feedback voltage sense | Regulated to 0.804V; connects to resistor divider tap - phase-lead capacitor (4.7–22pF) improves stability. |
Key Features
| Feature | Design Value |
|---|---|
| Silent Switcher® Architecture | Integrated dual-input, symmetric layout and internal bypass paths reduce common-mode EMI by >30dB vs conventional buck regulators. |
| Ultralow Quiescent Current | 2.5µA IQ in Burst Mode maintains regulation at zero load - extends battery runtime in always-on automotive sensors and telematics. |
| Fast Minimum On-Time (35ns) | Enables single-stage 48V-to-3.3V conversion at 2MHz, eliminating need for cascaded regulators and reducing BOM cost/size. |
| AEC-Q100 Grade H Qualification | Guaranteed operation from –40°C to +150°C junction temperature - suitable for engine control units, ADAS cameras, and transmission modules. |
| Spread Spectrum Modulation | ±22% triangular frequency dithering reduces peak EMI amplitude by spreading energy across bandwidth - simplifies EMC compliance testing. |
| Integrated Power Good (PG) | Open-drain PG pin signals valid regulation (±7.5% window) independent of EN state - enables safe power sequencing in multi-rail systems. |
Applications
| Automotive ADAS Camera Power Supply | Industrial PLC I/O Module |
|---|---|
Use Scenario: Powers image sensor, ISP, and interface circuitry in rear-view or surround-view camera modules mounted near engine compartments. IC Role / Device Role / Timing Role: Primary 12V-to-3.3V/5V step-down regulator delivering clean, low-noise power with EMI immunity for high-speed MIPI CSI-2 links. Use Value: AEC-Q100 H-grade rating ensures reliability at 150°C junction; Silent Switcher architecture prevents EMI-induced pixel noise or frame drop in video streams. | Use Scenario: Supplies isolated analog front-end, microcontroller, and communication transceivers in DIN-rail mounted programmable logic controllers. IC Role / Device Role / Timing Role: Main 24V-to-5V/3.3V converter supporting wide input variation (18–32V) and burst-mode operation during sleep cycles. Use Value: 2.5µA IQ extends battery backup duration during AC loss; 65V max input withstands 40V transients per IEC 61000-4-5. |
| GSM Base Station RF Power Amplifier Bias | Railway Signaling System Power |
Use Scenario: Generates stable 5V/3.5A bias rail for GaN or LDMOS RF power amplifiers in remote radio heads operating from 48V telecom supply. IC Role / Device Role / Timing Role: High-efficiency, high-frequency buck converter with fast transient response to handle dynamic PA envelope modulation. Use Value: 35ns min on-time enables direct 48V-to-5V conversion at 2MHz; <10mVP-P ripple prevents AM-to-PM distortion in RF output. | Use Scenario: Provides fail-safe 5V logic supply for trackside signaling controllers powered from 72V or 110V DC traction batteries. IC Role / Device Role / Timing Role: Input-transient-hardened step-down regulator with UVLO hysteresis and thermal shutdown for unregulated rail environments. Use Value: 65V absolute max rating and 130mV dropout at 1A ensure continuous operation during 100V surges; PG output triggers watchdog reset on undervoltage. |
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 |
|---|---|---|---|
| LT8640SUDC#PBF | Same architecture but 5A rated; 3.5µA IQ; 150°C max junction; no spread spectrum mode. | Higher output current capability; lacks spread spectrum EMI reduction feature. | Select when >3.5A continuous load is required and EMI filtering margin exists. |
| TPS54560QDGQRQ1 | 45V max input; 5A output; 14µA IQ; no Silent Switcher; SOIC-8 package; no PG or spread spectrum. | Lower input voltage range; larger solution size; higher EMI emissions; automotive-qualified but not AEC-Q100 H-grade. | Select for cost-sensitive 12V/24V systems where EMI is less constrained and thermal margin is ample. |
Compared with LT8640SUDC#PBF and TPS54560QDGQRQ1, the LT8641HUDC#PBF uniquely combines 65V input, AEC-Q100 H-grade, Silent Switcher EMI suppression, and 2.5µA IQ in a 3mm×4mm QFN - making it optimal for space-constrained, high-reliability automotive and industrial applications demanding lowest possible standby power and strict EMC compliance.
Availability
LT8641HUDC#PBF is available at Aetrix Electronics and suitable for automotive ADAS, industrial PLCs, railway signaling, and GSM base station power supplies requiring stable component supply, long-term lifecycle support, and AEC-Q100-compliant sourcing.
Supply support for LT8641HUDC#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 LT8641HUDC#PBF belongs to the Silent Switcher® monolithic step-down regulator product line, engineered specifically for ultra-low EMI and ultralow quiescent current in harsh automotive and industrial environments.
FAQ
What is the maximum input voltage rating for the LT8641HUDC#PBF?
The LT8641HUDC#PBF has an absolute maximum input voltage rating of 65V across VIN1 and VIN2 pins. This allows direct operation from 48V industrial buses and 60V automotive transients without external protection circuitry. Continuous operation is specified from 3V to 65V, with guaranteed performance over the full range per datasheet Section 6.
How does the LT8641HUDC#PBF achieve its 2.5µA quiescent current?
The LT8641HUDC#PBF achieves 2.5µA quiescent current in Burst Mode operation by completely disabling gate drivers, oscillator, and error amplifier between energy bursts while maintaining feedback regulation via a low-power comparator. This occurs only when the SYNC/MODE pin is grounded and light loads (<10mA) are present - verified at 12VIN→3.3VOUT per datasheet Figure G13.
Is the LT8641HUDC#PBF pin-compatible with other members of the LT864x family?
No, the LT8641HUDC#PBF is not pin-compatible with LT8640, LT8640S, or LT8643 due to differences in pin count, function assignment, and internal routing. For example, LT8641 includes dedicated VIN1/VIN2 and GND1/GND2 pairs for EMI optimization, while LT8640 uses single VIN/GND. Layout redesign is required for substitution.
What thermal derating applies to the LT8641HUDC#PBF at 150°C junction temperature?
Per datasheet Note 2 and Absolute Maximum Ratings, the LT8641HUDC#PBF is guaranteed for full specification operation up to +150°C junction temperature (Grade H). However, lifetime is derated above 125°C; continuous operation at 150°C reduces expected MTTF by ~50% versus 125°C - thermal design must maintain θJA ≤ 40°C/W with adequate copper area and vias per datasheet Figure F01.
Does the LT8641HUDC#PBF support output voltage tracking during power-up?
Yes, the LT8641HUDC#PBF supports output voltage tracking via the TR/SS pin. When TR/SS voltage is below 0.8V, the regulator forces FB to equal TR/SS voltage, enabling precise sequencing with other rails. An internal 1.9µA current source allows capacitor-based ramp control - confirmed in datasheet Section "PIN FUNCTIONS" and Figure G24.
LT8641HUDC#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 ~ 150°C (TJ)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount
- Supplier Device Package:
- 20-QFN (3x4)
LT8641HUDC#PBF FAQ
1.How can I place an order for LT8641HUDC#PBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LT8641HUDC#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 LT8641HUDC#PBF reliable?
The price and inventory of LT8641HUDC#PBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LT8641HUDC#PBF is usually 5 days.
3.What payment methods are accepted for LT8641HUDC#PBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LT8641HUDC#PBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LT8641HUDC#PBF?
LT8641HUDC#PBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LT8641HUDC#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 LT8641HUDC#PBF?
For technical support, including LT8641HUDC#PBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LT8641HUDC#PBF requirements.
6.How does Aetrix verify that LT8641HUDC#PBF is sourced from the original manufacturer or authorized distributors?
All LT8641HUDC#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 LT8641HUDC#PBF meets industry standards.
7.What is the process for return or replacement of LT8641HUDC#PBF?
All LT8641HUDC#PBF units undergo pre-shipment inspection (PSI). If there is an issue with LT8641HUDC#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 LT8641HUDC#PBF part is unused and in its original packaging.
Return procedure for LT8641HUDC#PBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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