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Analog Devices Inc. LT8640HUDCF#PBF
- Part No.:
- LT8640HUDCF#PBF
- Manufacturer:
- Analog Devices Inc.
- Package:
- 20-WFQFN, 18 Leads, Exposed Pad
- Datasheet:
-
LT8640HUDCF#PBF.pdf
- Description:
- IC REG BUCK ADJ 5A 20QFN
- Quantity:
- Payment:
- Shipping:
Inventory:431
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Product details
Overview
LT8640HUDCF#PBF from Analog Devices is a 42V, 5A synchronous step-down Silent Switcher DC/DC regulator with 2.5µA quiescent current in regulation, 30ns minimum on-time, and integrated power switches in a thermally enhanced 18-lead 3mm × 4mm side-wettable QFN package. It delivers up to 96% efficiency at 1MHz (12VIN→5VOUT) and supports automotive-grade operation from –40°C to +150°C junction temperature.
For engineers reviewing the LT8640HUDCF#PBF datasheet, LT8640HUDCF#PBF pinout, LT8640HUDCF#PBF application, or LT8640HUDCF#PBF equivalent, key selection criteria include ultralow EMI performance via Silent Switcher architecture, forced continuous mode (FCM) capability, spread spectrum modulation, AEC-Q100 qualification, and thermal robustness for high-reliability industrial and automotive power supplies.
Technical Context
The LT8640HUDCF#PBF implements peak current mode control with an internal 0.970V reference and programmable switching frequency (200kHz–3MHz) via external RT resistor. Its dual input rails (VIN1/VIN2) and dedicated GND1/GND2 paths minimize ground bounce and optimize EMI performance.
Silent Switcher architecture uses symmetrical layout and integrated bypass capacitors to suppress common-mode EMI; spread spectrum modulation (±22% frequency dithering) further reduces peak radiated emissions. The device supports four SYNC/MODE configurations: Burst Mode (ultralow IQ), forced continuous mode (fast transient response), spread spectrum FCM, and external clock synchronization.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 3.4V to 42V - supports wide-range industrial and automotive battery inputs including cold-crank and load-dump conditions. |
| Output Current | 5A continuous, 7A peak - enables single-chip 5V/5A or 3.3V/5A conversion without external boost or parallel stages. |
| Quiescent Current | 2.5µA in regulation - sustains >10-year battery life in always-on automotive modules (e.g., telematics, ADAS sensors). |
| Min. On-Time | 30ns - allows direct 42V-to-3.3V conversion at 2MHz, eliminating intermediate stages and reducing BOM count. |
| EMI Performance | CISPR 25 Class 5 compliant with filter - meets stringent automotive radiated emission limits without ferrite beads or complex shielding. |
| Thermal Rating | –40°C to +150°C junction - qualified per AEC-Q100 Grade H, enabling under-hood deployment without derating. |
| Switch RDS(on) | 67mΩ (top), 28mΩ (bottom) - minimizes conduction loss at full load, supporting >95% efficiency at 2MHz. |
Pinout & Package
LT8640HUDCF#PBF uses an 18-lead 3mm × 4mm plastic side-wettable QFN (UDCF) package with exposed SW pads (pins 21, 22) for enhanced thermal dissipation. Package thermal resistance: θJA = 40°C/W, θJC(PAD) = 12°C/W.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| BIAS (1) | Internal regulator bias supply | Accepts VOUT (3.3V–25V) to reduce VIN current draw and improve light-load efficiency. |
| INTVCC (2) | Internal 3.4V LDO output | Bypassed with ≥1µF ceramic capacitor; powers control logic and gate drivers. |
| BST (3) | Bootstrap capacitor connection | Drives top MOSFET gate above VIN; requires 0.1µF low-ESR ceramic placed adjacent to IC. |
| VIN1 (4), VIN2 (13) | Dual input power rails | Each requires dedicated 1µF local bypass; enables low-impedance, split-path input filtering for EMI reduction. |
| GND1 (6,7), GND2 (10,11) | Power switch return paths | Must be tied together and connected to solid ground plane; separates high-di/dt return currents from signal ground. |
| SW (8,9,21,22) | Power switch node | Exposed pads (21,22) must be soldered to SW trace for optimal thermal performance and EMI suppression. |
| EN/UV (14) | Enable and input undervoltage lockout | Hysteretic threshold (1.00V rise / 0.96V fall) enables programmable VIN brownout protection. |
| RT (15) | Frequency programming | Resistor to GND sets fSW from 200kHz to 3MHz; enables optimization of size vs. efficiency vs. EMI. |
| TR/SS (16) | Soft-start and output tracking | 1.9µA internal current source enables controlled VOUT ramp rate; supports sequencing with other rails. |
| SYNC/MODE (17) | Operating mode selection | Selects Burst Mode (GND), FCM (float), spread spectrum FCM (3–4V), or external sync (clock input). |
| GND (18) | System ground reference | Connects to system ground plane; completes feedback and PG circuit reference path. |
| PG (19) | Power good open-drain output | Asserts high when FB is within ±8% of 0.970V and no fault exists; valid above VIN = 3.4V. |
| FB (20) | Feedback voltage sense | Regulates to 0.970V ±0.6%; requires 4.7pF–22pF phase-lead capacitor between FB and VOUT for stability. |
Key Features
| Feature | Design Value |
|---|---|
| Silent Switcher® Architecture | Integrated dual-input/dual-GND layout and internal bypass caps reduce radiated EMI by >30dB vs. conventional buck regulators. |
| Ultralow Quiescent Current | 2.5µA IQ in regulation enables >10-year battery runtime in always-on automotive modules (e.g., CAN gateway, radar sensor). |
| Forced Continuous Mode (FCM) | Enables fast load-transient response (<50µs recovery) and eliminates low-frequency output ripple during pulse-skipping discontinuities. |
| Spread Spectrum Modulation | ±22% triangular dithering of switching frequency reduces peak EMI amplitude by 10–15dB, easing CISPR 25 compliance. |
| AEC-Q100 Grade H Qualification | Validated for –40°C to +150°C operation with lifetime reliability testing - suitable for engine control, ADAS, and infotainment systems. |
| Side-Wettable QFN Package | Enables automated optical inspection (AOI) of solder joints and improves thermal transfer to PCB copper layers for sustained 5A operation. |
Applications
| Automotive Infotainment Power | Industrial PLC I/O Module Supply |
|---|---|
Use Scenario: Powering 5V/3A SoC, display interface, and USB peripherals in head unit under varying battery conditions (9V–16V nominal, 42V load dump). IC Role / Device Role / Timing Role: Primary 42V-input synchronous buck regulator delivering regulated 5V with ultralow EMI to avoid RF interference with AM/FM and cellular receivers. Use Value: Silent Switcher architecture meets CISPR 25 Class 5 without external filters; 2.5µA IQ extends backup battery life during vehicle sleep mode. | Use Scenario: Generating isolated 5V/2A rail for digital I/O expansion cards in factory automation controllers operating in harsh 0°C–70°C ambient. IC Role / Device Role / Timing Role: High-efficiency, thermally robust DC/DC converter supplying FPGA, microcontroller, and level-shifting logic from 24V industrial bus. Use Value: 150°C junction rating ensures reliable operation without derating; side-wettable QFN enables AOI and long-term solder joint reliability. |
| GSM Base Station RF Power Amplifier Bias | Medical Portable Diagnostic Imaging |
Use Scenario: Providing low-noise 5V/4A bias for GaN RF power amplifiers in small-cell base stations requiring stable output under rapid load transients. IC Role / Device Role / Timing Role: High-bandwidth, forced continuous mode buck regulator minimizing output voltage droop during 10A peak RF envelope modulation. Use Value: FCM operation eliminates subharmonic ripple; 30ns min on-time supports direct 28V-to-5V conversion at 2MHz for compact filter design. | Use Scenario: Powering 3.3V/3A imaging sensor array and ADC in handheld ultrasound devices with Li-ion battery (3.0V–4.2V) and strict EMI limits near sensitive analog front-ends. IC Role / Device Role / Timing Role: Ultra-low-noise, high-efficiency buck converter delivering clean 3.3V from battery or USB-C PD input with minimal conducted/radiated noise. Use Value: Spread spectrum + Silent Switcher reduces EMI peaks below diagnostic imaging noise floor; 2.5µA IQ extends battery runtime during standby. |
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 |
|---|---|---|---|
| LT8640-1HUDCF#PBF | Identical package and thermal grade, but forces continuous mode (FCM) instead of pulse-skipping; higher light-load IQ (≈300µA vs. 2.5µA). | Better for fast transient loads (e.g., RF PA bias); unsuitable for ultra-low-power always-on applications. | Select LT8640-1HUDCF#PBF only when FCM is mandatory and light-load efficiency is secondary. |
| MPQ4433AGL-AEC1-P | 45V/6A AEC-Q100 buck; 17µA IQ; no spread spectrum; 60ns min on-time; 20-pin QFN (4×4mm). | Larger footprint; lacks Silent Switcher EMI suppression; lower thermal rating (125°C). | Consider MPQ4433AGL-AEC1-P only if board space permits larger package and EMI filtering can be added externally. |
Compared with LT8640-1HUDCF#PBF and MPQ4433AGL-AEC1-P, the LT8640HUDCF#PBF uniquely combines ultralow 2.5µA IQ, Silent Switcher EMI suppression, and AEC-Q100 Grade H rating in a compact side-wettable QFN-making it optimal for space-constrained, battery-sensitive automotive and industrial applications where both efficiency and EMI compliance are non-negotiable.
Availability
LT8640HUDCF#PBF is available at Aetrix Electronics and suitable for automotive infotainment systems, industrial PLC power modules, and medical portable diagnostics requiring stable component supply across extended temperature ranges and long production lifecycles.
Supply support for LT8640HUDCF#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 industrial, automotive, communications, and healthcare markets.
The LT8640 series belongs to Analog Devices' Silent Switcher µModule and monolithic regulator product line, designed specifically for high-efficiency, low-EMI power conversion in safety-critical and space-constrained applications such as ADAS, infotainment, and industrial automation.
FAQ
What is the maximum junction temperature specification for LT8640HUDCF#PBF?
The LT8640HUDCF#PBF is rated for operation from –40°C to +150°C junction temperature and is qualified per AEC-Q100 Grade H. This rating is validated through thermal characterization and lifetime reliability testing, enabling use in under-hood automotive environments and high-ambient industrial settings without derating at full 5A load.
Does LT8640HUDCF#PBF support spread spectrum modulation, and how is it enabled?
Yes, LT8640HUDCF#PBF supports spread spectrum modulation with ±22% frequency dithering. It is enabled by applying a DC voltage between 3V and 4V to the SYNC/MODE pin (pin 17), which activates spread spectrum mode while maintaining forced continuous operation. This feature reduces peak radiated EMI amplitude by 10–15dB, aiding CISPR 25 Class 5 compliance without external filtering.
Can LT8640HUDCF#PBF operate with a 42V input and deliver 3.3V output at 2MHz?
Yes, LT8640HUDCF#PBF supports direct 42V-to-3.3V conversion at 2MHz thanks to its 30ns minimum on-time. With appropriate inductor selection (e.g., 1µH) and layout optimization, it achieves >94% efficiency at 2A load. The device's Silent Switcher architecture ensures this high-frequency operation does not compromise EMI performance.
How does the BIAS pin improve efficiency in LT8640HUDCF#PBF?
The BIAS pin (pin 1) allows LT8640HUDCF#PBF to source internal regulator current from VOUT instead of VIN when VOUT ≥ 3.3V. This reduces total input current draw, especially at light loads, improving overall efficiency by up to 2–3% at 10mA output. For a 5V output, connecting BIAS directly to VOUT is recommended.
Is LT8640HUDCF#PBF pin-compatible with LT8640EUDC#PBF or LT8640IUDC#PBF?
No, LT8640HUDCF#PBF is not pin-compatible with LT8640EUDC#PBF or LT8640IUDC#PBF. While all share the same 18-lead functional pinout, LT8640HUDCF#PBF uses the side-wettable UDCF package (LHJK marking), whereas LT8640EUDC#PBF/IUDC#PBF use standard UDC QFN (LGNJ). The UDCF package has different solder pad geometry and requires distinct PCB footprint and stencil design.
LT8640HUDCF#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):
- 3.4V
- Voltage - Input (Max):
- 42V
- Voltage - Output (Min/Fixed):
- 0.97V
- Voltage - Output (Max):
- 42V
- Current - Output:
- 5A
- Frequency - Switching:
- 210kHz ~ 2MHz
- Synchronous Rectifier:
- Yes
- Operating Temperature:
- -40°C ~ 150°C (TJ)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount, Wettable Flank
- Supplier Device Package:
- 20-QFN (3x4)
LT8640HUDCF#PBF FAQ
1.How can I place an order for LT8640HUDCF#PBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LT8640HUDCF#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 LT8640HUDCF#PBF reliable?
The price and inventory of LT8640HUDCF#PBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LT8640HUDCF#PBF is usually 5 days.
3.What payment methods are accepted for LT8640HUDCF#PBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LT8640HUDCF#PBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LT8640HUDCF#PBF?
LT8640HUDCF#PBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LT8640HUDCF#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 LT8640HUDCF#PBF?
For technical support, including LT8640HUDCF#PBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LT8640HUDCF#PBF requirements.
6.How does Aetrix verify that LT8640HUDCF#PBF is sourced from the original manufacturer or authorized distributors?
All LT8640HUDCF#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 LT8640HUDCF#PBF meets industry standards.
7.What is the process for return or replacement of LT8640HUDCF#PBF?
All LT8640HUDCF#PBF units undergo pre-shipment inspection (PSI). If there is an issue with LT8640HUDCF#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 LT8640HUDCF#PBF part is unused and in its original packaging.
Return procedure for LT8640HUDCF#PBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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