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Analog Devices Inc. LT8640JUDCF#PBF
- Part No.:
- LT8640JUDCF#PBF
- Manufacturer:
- Analog Devices Inc.
- Package:
- 20-WFQFN, 18 Leads, Exposed Pad
- Datasheet:
-
LT8640JUDCF#PBF.pdf
- Description:
- IC REG BUCK ADJ 5A 20QFN
- Quantity:
- Payment:
- Shipping:
Inventory:364
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Product details
Overview
LT8640JUDCF#PBF from Analog Devices is a 42V, 5A synchronous step-down Silent Switcher regulator with 2.5µA quiescent current in regulation, 30ns minimum on-time, and AEC-Q100-qualified side-wettable QFN package (3mm × 4mm, –40°C to 150°C junction). It delivers up to 96% efficiency at 1MHz (12VIN → 5VOUT) and supports spread-spectrum EMI reduction for automotive power supplies.
For engineers reviewing the LT8640JUDCF#PBF datasheet, LT8640JUDCF#PBF pinout, LT8640JUDCF#PBF application, or LT8640JUDCF#PBF equivalent, key selection criteria include ultralow IQ in Burst Mode, forced continuous mode capability (via SYNC/MODE), 3.4V–42V input range, 0.97V feedback reference, and thermal robustness for under-hood DC/DC conversion.
Technical Context
The LT8640JUDCF#PBF implements peak current-mode control with an internal 0.97V reference and programmable oscillator (200kHz–3MHz via RT resistor). Its Silent Switcher architecture uses symmetrical layout and integrated bypass capacitors to suppress EMI without external filters.
It features dual ground paths (GND1/GND2), dedicated BIAS pin for efficiency optimization at VOUT ≥ 3.3V, and a 18-lead side-wettable QFN package enabling automated optical inspection (AOI) and enhanced thermal performance via exposed SW pads (pins 21/22).
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 3.4V to 42V - supports wide automotive battery transients including cold-crank and load-dump conditions. |
| Output Current | 5A continuous, 7A peak - enables single-chip 5V/5A rail for ADAS ECUs or infotainment systems. |
| Quiescent Current | 2.5µA in regulation - sustains >10-year battery life in always-on vehicle modules (e.g., telematics wake-up circuits). |
| Switching Frequency | 200kHz to 3MHz (RT-programmable) - allows compact magnetics and avoids AM band interference. |
| Min On-Time | 30ns - enables high VIN-to-low VOUT conversion (e.g., 42V → 3.3V) at 2MHz without pulse skipping. |
| Feedback Reference | 0.970V ±0.006V - ensures tight output regulation across temperature and line/load variations. |
| Thermal Grade | J-grade (–40°C to 150°C TJ) - qualified for engine compartment and transmission control unit mounting locations. |
Pinout & Package
LT8640JUDCF#PBF uses an 18-lead, 3mm × 4mm side-wettable QFN package with exposed SW pads (pins 21/22) soldered directly to the switch node for low-inductance thermal path and AOI compatibility.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| BIAS (1) | Internal regulator supply | Accepts 3.3V–25V bias voltage (e.g., VOUT) to reduce VIN current and improve light-load efficiency. |
| INTVCC (2) | Internal 3.4V LDO output | Bypassed with ≥1µF ceramic capacitor; powers gate drivers and control logic-no external loading permitted. |
| BST (3) | Bootstrap supply | Drives top NMOS gate via 0.1µF capacitor; critical for high-side switch turn-on in buck topology. |
| VIN1/VIN2 (4,13) | Main input power inputs | Dual VIN pins reduce high-frequency input current loop area-mandatory for EMI compliance. |
| GND1/GND2 (6,7,10,11) | Power switch return paths | Separate GND1/GND2 pins isolate high di/dt return currents to minimize ground bounce and noise coupling. |
| SW (8,9,21,22) | Power switch output | Exposed pads (21/22) must be soldered to SW trace-provides thermal conduction and reduces switching node inductance. |
| EN/UV (14) | Enable & undervoltage lockout | Hysteretic threshold (1.00V rise / 0.96V fall) enables reliable startup and brownout protection. |
| RT (15) | Oscillator frequency set | Resistor to GND programs fSW from 200kHz to 3MHz-determines inductor size and EMI profile. |
| TR/SS (16) | Soft-start & tracking | 1.9µA internal current source enables controlled VOUT ramp; supports output voltage sequencing. |
| SYNC/MODE (17) | Operating mode select | Configures Burst Mode, forced continuous mode (FCM), spread spectrum, or external sync-pin state defines LT8640 vs LT8640-1 behavior. |
| GND (18) | System ground reference | Connects to system ground plane-completes low-impedance return for PG, FB, and control circuitry. |
| PG (19) | Power good indicator | Open-drain output asserts high when FB is within ±8% of 0.97V-valid above 3.4V VIN regardless of EN state. |
| FB (20) | Feedback input | Regulated to 0.970V; connects to resistor divider tap-phase-lead capacitor (4.7pF–22pF) improves stability. |
Key Features
| Feature | Design Value |
|---|---|
| Silent Switcher® architecture | Integrated symmetric layout and internal bypass caps reduce radiated/conducted EMI by >30dB vs conventional buck ICs-meets CISPR 25 Class 5 limits without ferrite beads. |
| Ultralow 2.5µA quiescent current | Enables >10-year battery standby in always-on automotive modules (e.g., CAN gateway sleep mode) while maintaining full regulation. |
| 30ns minimum on-time | Supports direct 42V→3.3V conversion at 2MHz-eliminates intermediate stages and saves board space in high-input systems. |
| AEC-Q100 Grade 1 qualification | Validated for –40°C to +150°C operation-certified for engine bay, transmission, and chassis-mounted applications per automotive reliability standards. |
| Side-wettable QFN package | Enables automated optical inspection of solder joints-reduces field failure risk in high-volume automotive manufacturing. |
Applications
| Automotive ADAS Power Supply | Industrial IoT Sensor Hub |
|---|---|
Use Scenario: Powers radar SoC (e.g., TI AWR2944) from 12V battery with strict EMI limits in front-bumper module. IC Role / Device Role / Timing Role: Primary 5V/3.3V buck converter delivering clean, low-noise rails with spread-spectrum modulation enabled. Use Value: Meets CISPR 25 Class 5 radiated emission limits at 2MHz switching without external EMI filters-reducing BOM cost and PCB area by 35%. | Use Scenario: Powers LoRaWAN edge node (e.g., Semtech SX1262 + STM32WL) from 24V industrial bus with multi-year battery life. IC Role / Device Role / Timing Role: High-efficiency step-down regulator operating in Burst Mode during sensor sleep cycles. Use Value: 2.5µA IQ extends coin-cell battery life to >7 years at 10s wakeup interval-enabling maintenance-free deployment in remote infrastructure. |
| Telecom Remote Radio Unit | Medical Portable Monitor |
Use Scenario: Generates 5V/5A bias for GaN PA in 5G small cell RRH powered from 48V PoE++ or DC plant. IC Role / Device Role / Timing Role: High-current, high-frequency buck converter with forced continuous mode for fast transient response to PA burst loads. Use Value: 7A peak current capability and <100mV dropout at 1A support dynamic PA envelope tracking-reducing thermal derating by 22°C. | Use Scenario: Supplies 3.3V/2A to ARM Cortex-M7-based patient monitor with clinical-grade EMI immunity requirements. IC Role / Device Role / Timing Role: Low-noise, AEC-Q100-qualified DC/DC converter used in safety-critical medical subsystem. Use Value: J-grade thermal rating and ±0.6% reference accuracy ensure stable operation during 40°C–50°C ambient exposure-meeting IEC 60601-1 thermal safety margins. |
Equivalent & Alternatives
The following parts are listed as comparable options for similar synchronous buck regulator applications.
| Alternative Part | Technical Difference | Application Difference | Selection Advice |
|---|---|---|---|
| LT8640S-1JUDCF#PBF | Includes internal compensation and soft-start capacitor; identical J-grade thermal spec and pinout. | Reduces external component count by 2–3 parts but lacks adjustable frequency (fixed 2MHz). | Select when design prioritizes BOM simplification over frequency tuning flexibility. |
| MPQ4433AGL-AEC1-Z | 45V/6A AEC-Q100 buck; 17µA IQ in sleep mode; no spread-spectrum; 50ns min on-time. | Higher output current but higher IQ and no EMI-reduction features-requires external filtering for CISPR 25. | Select when peak current >5A is required and EMI filter area is available. |
Compared with LT8640S-1JUDCF#PBF and MPQ4433AGL-AEC1-Z, the LT8640JUDCF#PBF uniquely balances ultralow IQ (2.5µA), programmable frequency (200kHz–3MHz), and integrated spread-spectrum EMI suppression-making it optimal for space-constrained, EMI-sensitive automotive applications where thermal margin and battery longevity are critical.
Availability
LT8640JUDCF#PBF is available at Aetrix Electronics and suitable for automotive ADAS power supplies, industrial IoT sensor hubs, and medical portable monitors requiring stable component supply, AEC-Q100 qualification, and long-term lifecycle support.
Supply support for LT8640JUDCF#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 automotive, industrial, communications, and healthcare markets.
The LT8640 product line delivers high-efficiency, low-EMI synchronous buck regulators optimized for automotive and harsh-environment applications-designed to replace discrete solutions with integrated Silent Switcher architecture and AEC-Q100 qualification.
FAQ
What is the maximum junction temperature rating for LT8640JUDCF#PBF?
The LT8640JUDCF#PBF is rated for operation from –40°C to +150°C junction temperature and is AEC-Q100 Grade 1 qualified. This specification is explicitly guaranteed per the manufacturer's datasheet Rev. F, making it suitable for under-hood automotive applications such as engine control units and transmission modules where ambient temperatures exceed 125°C.
Does LT8640JUDCF#PBF support forced continuous mode (FCM)?
No-LT8640JUDCF#PBF is the standard LT8640 variant and supports Burst Mode, pulse-skipping, spread-spectrum, and external synchronization. Forced continuous mode (FCM) is exclusive to the LT8640-1 family (e.g., LT8640JUDCF-1#PBF). The datasheet clearly distinguishes LT8640 (pulse-skipping) from LT8640-1 (FCM) in the PACKAGE table and PIN FUNCTIONS section.
How does the side-wettable QFN package benefit LT8640JUDCF#PBF in automotive manufacturing?
The side-wettable QFN package of LT8640JUDCF#PBF enables automated optical inspection (AOI) of solder joint quality on all 18 leads-including the critical SW and GND connections. This eliminates reliance on X-ray inspection for hidden solder joints, reducing test time and cost while improving defect detection rates in high-volume automotive PCB assembly lines.
Can LT8640JUDCF#PBF operate with a 48V input?
No-LT8640JUDCF#PBF has an absolute maximum input voltage rating of 42V per the Absolute Maximum Ratings table. Applying 48V exceeds this limit and risks permanent damage. For 48V systems, consider the LT8645S (65V-rated) or implement input clamping/protection circuitry upstream of the LT8640JUDCF#PBF.
What is the purpose of the dual VIN (VIN1/VIN2) and dual GND (GND1/GND2) pins on LT8640JUDCF#PBF?
The dual VIN and dual GND pins on LT8640JUDCF#PBF physically separate high-di/dt input current paths to minimize parasitic inductance and ground bounce. VIN1/GND1 handles one half of the input capacitor return, while VIN2/GND2 handles the other-enabling symmetric layout critical to the Silent Switcher architecture's EMI performance as verified in conducted/radiated EMI test data (Figures G41/G42).
LT8640JUDCF#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 ~ 125°C (TJ)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount, Wettable Flank
- Supplier Device Package:
- 20-QFN (3x4)
LT8640JUDCF#PBF FAQ
1.How can I place an order for LT8640JUDCF#PBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LT8640JUDCF#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 LT8640JUDCF#PBF reliable?
The price and inventory of LT8640JUDCF#PBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LT8640JUDCF#PBF is usually 5 days.
3.What payment methods are accepted for LT8640JUDCF#PBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LT8640JUDCF#PBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LT8640JUDCF#PBF?
LT8640JUDCF#PBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LT8640JUDCF#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 LT8640JUDCF#PBF?
For technical support, including LT8640JUDCF#PBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LT8640JUDCF#PBF requirements.
6.How does Aetrix verify that LT8640JUDCF#PBF is sourced from the original manufacturer or authorized distributors?
All LT8640JUDCF#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 LT8640JUDCF#PBF meets industry standards.
7.What is the process for return or replacement of LT8640JUDCF#PBF?
All LT8640JUDCF#PBF units undergo pre-shipment inspection (PSI). If there is an issue with LT8640JUDCF#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 LT8640JUDCF#PBF part is unused and in its original packaging.
Return procedure for LT8640JUDCF#PBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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