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Analog Devices Inc. LT8640JUDCF-1#WTRPBF
- Part No.:
- LT8640JUDCF-1#WTRPBF
- Manufacturer:
- Analog Devices Inc.
- Package:
- 20-WFQFN, 18 Leads, Exposed Pad
- Datasheet:
-
LT8640JUDCF-1#WTRPBF.pdf
- Description:
- IC REG BUCK ADJ 5A 20QFN
- Quantity:
- Payment:
- Shipping:
Inventory:3,392
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Product details
Overview
LT8640JUDCF-1#WTRPBF from Analog Devices is a 42V, 5A synchronous step-down Silent Switcher regulator with forced continuous mode (FCM), 2.5µA quiescent current in regulation, 30ns minimum on-time, and AEC-Q100 Grade J (–40°C to 150°C) qualification for automotive power supplies.
For engineers reviewing the LT8640JUDCF-1#WTRPBF datasheet, LT8640JUDCF-1#WTRPBF pinout, LT8640JUDCF-1#WTRPBF application, or LT8640JUDCF-1#WTRPBF equivalent, key selection criteria include ultralow EMI performance, spread spectrum capability, FCM transient response, thermal robustness up to 150°C junction, and side-wettable QFN package for automated optical inspection.
Technical Context
The LT8640JUDCF-1#WTRPBF implements peak current mode control with internal 0.97V reference and 200kHz–3MHz programmable switching frequency via RT resistor. Its Silent Switcher architecture uses integrated input capacitors and symmetrical layout to suppress common-mode EMI.
Unlike the LT8640, this variant fixes forced continuous mode (FCM) operation when SYNC/MODE is floating-enabling negative inductor current, fast load-step response, and stable light-load behavior without pulse skipping. It supports BIAS pin supply from VOUT ≥3.3V to reduce VIN current and improve efficiency.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 3.4V to 42V - supports wide automotive battery transients including cold-crank (4.5V) and load-dump (40V+) |
| Output Current | 5A continuous, 7A peak - sustains high-current bursts without thermal shutdown under proper PCB layout |
| Quiescent Current | 2.5µA at 12VIN→3.3VOUT - enables >10-year battery life in always-on automotive modules |
| Min On-Time | 30ns - enables high-frequency, high-VIN-to-low-VOUT conversion (e.g., 24V→1.2V @ 2MHz) |
| EMI Performance | CISPR 25 Class 5 compliant with filter - meets stringent automotive radiated/conducted emission limits without shielding |
| Thermal Rating | J-grade: –40°C to 150°C TJ - qualified for under-hood applications with no derating up to 125°C ambient |
| Package | 18-lead 3mm × 4mm side-wettable QFN - enables AOI-compatible solder joint inspection and enhanced thermal transfer via exposed SW pads |
Pinout & Package
LT8640JUDCF-1#WTRPBF uses an 18-lead, 3mm × 4mm plastic side-wettable QFN package with exposed SW pads (pins 21, 22) for thermal and electrical connection to the switch node. Pin 5 and pin 12 are omitted per JEDEC outline deviation.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| BIAS (1) | Internal regulator auxiliary supply | Accepts 3.3V–25V input to power INTVCC; reduces VIN current and improves light-load efficiency when tied to VOUT |
| INTVCC (2) | Internal 3.4V regulator output | Bypassed with ≥1µF ceramic capacitor; powers gate drivers and control logic; not for external loading |
| BST (3) | Bootstrap supply for top MOSFET gate | Requires 0.1µF ceramic capacitor between BST and SW; enables high-side NMOS drive above VIN |
| VIN1 (4), VIN2 (13) | Dual input power inputs | Each requires dedicated 1µF local bypass; shared bulk cap connects to both-reduces high-frequency loop area and EMI |
| GND1 (6,7), GND2 (10,11) | Power switch return paths | Must be shorted together and connected to low-impedance ground plane; critical for EMI and thermal performance |
| SW (8,9,21,22) | Switch node outputs | Pins 8/9 are signal SW; pins 21/22 are exposed thermal pads soldered directly to SW copper-lowers θJC to 12°C/W |
| EN/UV (14) | Enable and input undervoltage lockout | Hysteretic threshold (0.96V/1.00V) allows programmable VIN start-up using resistor divider |
| RT (15) | Oscillator frequency programming | Resistor to GND sets fSW from 200kHz to 3MHz; tolerance and tempco directly impact regulation accuracy |
| TR/SS (16) | Soft-start and output tracking | 1.9µA internal current source enables controlled VOUT ramp; voltage <0.97V forces FB = TR/SS for sequencing |
| SYNC/MODE (17) | Operating mode selection | Floating = FCM; grounded = Burst Mode; 3–4V = spread spectrum + FCM; driven clock = external sync + FCM |
| GND (18) | System ground reference | Connects to system ground plane; separates signal ground from power ground paths in multi-layer layouts |
| PG (19) | Power good open-drain output | Asserts high when FB is within ±8% of 0.97V and VIN >3.4V; pulls down with 2kΩ typical resistance |
| FB (20) | Feedback voltage sense | Regulated to 0.970V ±0.006V; requires 4.7–22pF phase-lead capacitor from FB to VOUT for stability |
Key Features
| Feature | Design Value |
|---|---|
| Silent Switcher® architecture | Integrated input caps + symmetric layout reduce common-mode EMI by >30dB vs conventional buck, enabling Class 5 compliance without shielding |
| Forced Continuous Mode (FCM) | Eliminates low-load frequency variation and output ripple discontinuity-ensures predictable transient response across full 0–5A range |
| Spread spectrum modulation | ±20% triangular dithering of switching frequency reduces peak EMI amplitude by 10–15dB, easing filter design and board space |
| AEC-Q100 Grade J qualification | Validated for 150°C junction operation with lifetime testing-supports engine control, ADAS, and transmission control units |
| Side-wettable QFN package | Exposed SW pads on package edges enable automated optical inspection of solder joints-critical for zero-defect automotive manufacturing |
Applications
| Automotive Infotainment Power | ADAS Camera Module Supply |
|---|---|
Use Scenario: Powering SoC, DDR memory, and display interface in head-unit systems with 12V battery input and strict EMC requirements. IC Role / Device Role / Timing Role: Primary 5V/3.3V/1.2V point-of-load regulator delivering clean, low-noise power with synchronized switching to avoid beat frequencies. Use Value: Spread spectrum + Silent Switcher ensures CISPR 25 Class 5 pass without ferrite beads or metal shields-reducing BOM cost and board area by >25%. | Use Scenario: Providing stable 3.3V/1.8V rails for high-resolution image sensors and ISP processors in surround-view cameras. IC Role / Device Role / Timing Role: High-efficiency, low-ripple buck converter operating in FCM to maintain tight output regulation during rapid scene brightness changes. Use Value: 2.5µA IQ and FCM enable <100mVpp ripple at 10mA load-preventing sensor pattern noise and ensuring accurate auto-exposure control. |
| Industrial PLC I/O Module | GSM Base Station RF Power Supply |
Use Scenario: Generating isolated 5V bias for digital isolators and analog front-ends in harsh industrial environments with wide temperature swings. IC Role / Device Role / Timing Role: Robust DC/DC controller with UVLO hysteresis and thermal shutdown, operating continuously from –40°C to +85°C ambient. Use Value: Grade J rating and 150°C max TJ allow full 5A output derating only above 105°C ambient-extending field life in unventilated enclosures. | Use Scenario: Supplying 5V/3A to GSM PA driver stages requiring ultra-low EMI to prevent receiver desensitization. IC Role / Device Role / Timing Role: Low-noise, high-frequency buck converter synchronized to baseband clock to eliminate mixing spurs in RF band. Use Value: External clock sync capability enables precise alignment of switching edges-suppressing 2nd/3rd harmonic interference in 900/1800MHz bands. |
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 |
|---|---|---|---|
| LT8640JUDCF#WTRPBF | Pulse-skipping mode default; no FCM; SYNC/MODE floating enables burst-free operation only at medium loads | Better light-load efficiency than LT8640JUDCF-1#WTRPBF below 100mA, but slower transient response and higher output ripple at light loads | Select when lowest possible IQ dominates over transient performance and EMI is less critical |
| LMQ66430QRNXTQ1 | 36V, 3A, 2.5µA IQ, integrated compensation; no spread spectrum; smaller 3mm × 2mm QFN | Lacks side-wettable leads and AEC-Q100 Grade J rating; limited to 125°C TJ; lower current capacity | Select for space-constrained, non-under-hood automotive modules where 3A output suffices and EMI filtering is acceptable |
Compared with LT8640JUDCF#WTRPBF and LMQ66430QRNXTQ1, the LT8640JUDCF-1#WTRPBF uniquely combines AEC-Q100 Grade J qualification, forced continuous mode for sub-100ns load-step response, and side-wettable QFN for automotive process control-making it the only choice for high-reliability, high-transient automotive power rails.
Availability
LT8640JUDCF-1#WTRPBF is available at Aetrix Electronics and suitable for automotive infotainment, ADAS camera modules, industrial PLC I/O, and GSM RF power supplies requiring stable component supply, AEC-Q100 compliance, and production-ready packaging.
Supply support for LT8640JUDCF-1#WTRPBF 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 precision instrumentation, industrial automation, communications, and automotive markets.
The LT8640/LT8640-1 product line was designed specifically for automotive and industrial applications demanding ultralow EMI, high efficiency across wide load ranges, and extended temperature reliability-leveraging Silent Switcher architecture and AEC-Q100 qualification.
FAQ
What is the maximum junction temperature rating for LT8640JUDCF-1#WTRPBF?
The LT8640JUDCF-1#WTRPBF is AEC-Q100 Grade J qualified with a guaranteed operating junction temperature range of –40°C to 150°C. This rating is validated through accelerated lifetime testing and thermal characterization, enabling use in under-hood automotive applications without derating up to 125°C ambient temperature when properly mounted on a 2oz copper PCB with thermal vias.
How does LT8640JUDCF-1#WTRPBF differ from LT8640JUDCF#WTRPBF in operating mode?
The LT8640JUDCF-1#WTRPBF defaults to forced continuous mode (FCM) when SYNC/MODE is floating, allowing negative inductor current and fast transient response. In contrast, LT8640JUDCF#WTRPBF enters pulse-skipping mode under the same condition-resulting in variable frequency and higher output ripple at light loads. Both support Burst Mode (SYNC/MODE = GND) and spread spectrum (SYNC/MODE = 3–4V).
Can LT8640JUDCF-1#WTRPBF synchronize to an external clock, and what is the required signal format?
Yes, LT8640JUDCF-1#WTRPBF supports external clock synchronization via the SYNC/MODE pin. The input must be a CMOS-level square wave with rail-to-rail swing (0V to >2.3V), 50% ±10% duty cycle, and frequency between 200kHz and 3MHz. During sync, the device operates in forced continuous mode with switching edges aligned to the rising edge of the external clock.
What is the purpose of the side-wettable leads on the LT8640JUDCF-1#WTRPBF package?
The side-wettable leads on the LT8640JUDCF-1#WTRPBF package enable automated optical inspection (AOI) of solder fillets along the vertical edges of the QFN body. This provides 100% solder joint quality verification-critical for zero-defect requirements in automotive manufacturing-and improves thermal conduction from the exposed SW pads to the PCB.
Does LT8640JUDCF-1#WTRPBF require external compensation components?
No, LT8640JUDCF-1#WTRPBF features internal compensation and requires no external compensation network. Stability is ensured via the internal error amplifier and slope compensation. Only the feedback resistive divider, input/output capacitors, inductor, BST capacitor, and optional FB-to-VOUT phase-lead capacitor (4.7–22pF) are needed for basic operation.
LT8640JUDCF-1#WTRPBF Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- Silent Switcher®1
- Package/Case:
- 20-WFQFN, 18 Leads, Exposed Pad
- Packaging:
- Tape & Reel (TR)
- 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:
- 200kHz ~ 3MHz
- Synchronous Rectifier:
- Yes
- Operating Temperature:
- -40°C ~ 150°C (TJ)
- Grade:
- Automotive
- Qualification:
- AEC-Q100
- Mounting Type:
- Surface Mount, Wettable Flank
- Supplier Device Package:
- 20-QFN (3x4)
LT8640JUDCF-1#WTRPBF FAQ
1.How can I place an order for LT8640JUDCF-1#WTRPBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LT8640JUDCF-1#WTRPBF 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-1#WTRPBF reliable?
The price and inventory of LT8640JUDCF-1#WTRPBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LT8640JUDCF-1#WTRPBF is usually 5 days.
3.What payment methods are accepted for LT8640JUDCF-1#WTRPBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LT8640JUDCF-1#WTRPBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LT8640JUDCF-1#WTRPBF?
LT8640JUDCF-1#WTRPBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LT8640JUDCF-1#WTRPBF 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-1#WTRPBF?
For technical support, including LT8640JUDCF-1#WTRPBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LT8640JUDCF-1#WTRPBF requirements.
6.How does Aetrix verify that LT8640JUDCF-1#WTRPBF is sourced from the original manufacturer or authorized distributors?
All LT8640JUDCF-1#WTRPBF 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-1#WTRPBF meets industry standards.
7.What is the process for return or replacement of LT8640JUDCF-1#WTRPBF?
All LT8640JUDCF-1#WTRPBF units undergo pre-shipment inspection (PSI). If there is an issue with LT8640JUDCF-1#WTRPBF, 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-1#WTRPBF part is unused and in its original packaging.
Return procedure for LT8640JUDCF-1#WTRPBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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