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Analog Devices Inc. LT8640JUDCF-1#PBF
- Part No.:
- LT8640JUDCF-1#PBF
- Manufacturer:
- Analog Devices Inc.
- Package:
- 20-WFQFN, 18 Leads, Exposed Pad
- Datasheet:
-
LT8640JUDCF-1#PBF.pdf
- Description:
- IC REG BUCK ADJ 5A 20QFN
- Quantity:
- Payment:
- Shipping:
Inventory:2,885
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Product details
Overview
LT8640JUDCF-1#PBF 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 qualified for automotive applications. It delivers up to 96% efficiency at 1MHz (12VIN→5VOUT) and supports input ranges from 3.4V to 42V.
For engineers reviewing the LT8640JUDCF-1#PBF datasheet, LT8640JUDCF-1#PBF pinout, LT8640JUDCF-1#PBF application, or LT8640JUDCF-1#PBF equivalent, key selection criteria include ultralow EMI performance, thermal robustness up to 150°C junction temperature, FCM operation for fast transient response, and side-wettable QFN package for automated optical inspection.
Technical Context
The LT8640JUDCF-1#PBF employs peak current mode control with an internal 0.970V reference and programmable oscillator (200kHz–3MHz via RT resistor). Its Silent Switcher architecture integrates split VIN and GND paths plus integrated bypass capacitors to suppress common-mode EMI.
Unlike the LT8640, the LT8640-1 variant uses forced continuous mode by default when SYNC/MODE is floating-enabling negative inductor current, improved load-step response, and stable frequency under light loads. It disables FCM only when VIN exceeds 39V or FB rises >12% above reference.
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+). |
| Continuous Output Current | 5A - sustains full-load operation with proper PCB thermal design and 3mm × 4mm side-wettable QFN package. |
| Quiescent Current | 2.5µA - enables >10-year battery life in always-on automotive modules (e.g., telematics, ADAS sensors). |
| Minimum On-Time | 30ns - allows high-frequency, high-VIN-to-low-VOUT conversion (e.g., 42V→3.3V at 2MHz). |
| Switching Frequency Range | 200kHz to 3MHz - adjustable via RT resistor; supports compact magnetics and avoids AM/FM radio bands. |
| Junction Temperature Range | –40°C to +150°C - J-grade qualification ensures reliability in engine bay and powertrain environments. |
| EMI Performance | CISPR 25 Class 5 compliant - meets automotive radiated/conducted emission limits without external filters in typical layouts. |
Pinout & Package
LT8640JUDCF-1#PBF uses an 18-lead, 3mm × 4mm plastic side-wettable QFN package (LHGX marking) with exposed SW pads (pins 21, 22) for thermal and electrical connection. The package supports automated optical inspection (AOI) of solder joints.
| 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 gate drivers and control logic-no external loading permitted. |
| BST (3) | Bootstrap capacitor node | Requires 0.1µF ceramic capacitor between BST and SW to drive high-side NMOS gate above VIN. |
| VIN1, VIN2 (4, 13) | Main input power inputs | Each requires dedicated 1µF ceramic bypass; dual inputs reduce high-frequency loop inductance for EMI suppression. |
| GND1, GND2 (6, 7, 10, 11) | Power switch return paths | Must be tied together and connected to low-impedance ground plane; critical for EMI and thermal performance. |
| SW (8, 9, 21, 22) | Switch node outputs | Exposed pads (21, 22) must be soldered to SW trace for thermal conduction; primary EMI source-keep layout area minimal. |
| EN/UV (14) | Enable and undervoltage lockout | Hysteretic threshold (0.96V/1.00V) enables programmable input UVLO using external resistor divider from VIN. |
| RT (15) | Oscillator frequency programming | Resistor to GND sets switching frequency (e.g., 60.4kΩ = ~2MHz); tolerance directly impacts regulation accuracy. |
| TR/SS (16) | Soft-start and output tracking | 1.9µA internal current source enables controlled VOUT ramp-up; also supports voltage sequencing with external sources. |
| SYNC/MODE (17) | Operating mode selection | Floating = Forced Continuous Mode (FCM); grounded = Burst Mode; high = spread spectrum or sync-no pull-up required. |
| GND (18) | Analog/system ground reference | Connect to system ground plane; separate from power GNDs but tied at single point to minimize noise coupling. |
| PG (19) | Power good open-drain output | Asserts high when FB is within ±7.5% of 0.970V and no fault (thermal, UVLO, overcurrent) is present. |
| FB (20) | Feedback voltage sense | Regulates to 0.970V ±0.6%; requires RC network (e.g., 4.7pF + resistor divider) for stability across operating conditions. |
Key Features
| Feature | Design Value |
|---|---|
| Silent Switcher® architecture | Integrated dual-input/dual-GND paths and internal bypass caps reduce radiated EMI by >30dB vs conventional buck regulators. |
| Forced Continuous Mode (FCM) | Enables consistent 2MHz operation down to zero load-critical for low-noise, fast-transient applications like radar power supplies. |
| Side-wettable QFN (SWQFN) | Facilitates AOI of solder fillets on all 18 leads-ensures manufacturing yield and field-reliability in automotive production. |
| AEC-Q100 Grade 1 qualification | Validated for –40°C to +150°C operation with HTOL, TC, and ESD testing-meets functional safety requirements for ASIL-B systems. |
| Ultralow 2.5µA quiescent current | Maintains regulation at microamp loads-enables always-on functionality in vehicle security modules and CAN wake-up circuits. |
| 30ns minimum on-time | Supports direct 42V→3.3V conversion at 2MHz, eliminating intermediate stages and reducing BOM count in high-voltage systems. |
Applications
| Automotive Infotainment Power | ADAS Camera Module Supply |
|---|---|
|
Use Scenario: Powering SoC, DDR memory, and display interfaces in head units with strict EMI limits and cold-crank survival. IC Role / Device Role / Timing Role: Primary 5V/5A DC/DC converter delivering regulated output with <10mVP-P ripple and CISPR 25 compliance. Use Value: Eliminates need for external EMI filters; maintains regulation during 4.5V cranking events due to 3.4V min VIN and 100mV dropout at 1A. |
Use Scenario: Supplying image sensor, ISP, and serializer in surround-view cameras mounted near engine compartments. IC Role / Device Role / Timing Role: High-efficiency, thermally robust 3.3V/3A supply operating continuously at 125°C ambient. Use Value: J-grade 150°C junction rating and side-wettable QFN ensure long-term reliability; FCM mode prevents frequency jitter during video frame capture. |
| GSM Base Station RF Power Amplifier Bias | Industrial PLC I/O Module Supply |
|
Use Scenario: Generating clean, low-noise 5V bias for GaN RF power amplifiers requiring stable voltage under pulsed 7A transients. IC Role / Device Role / Timing Role: High-current buck regulator with 7A peak capability and <50ns transient response to load steps. Use Value: Forced Continuous Mode enables predictable switching during burst transmission; Silent Switcher reduces RF interference in adjacent receive bands. |
Use Scenario: Providing isolated 5V/2A supply for digital I/O channels in DIN-rail mounted controllers exposed to 40V surges. IC Role / Device Role / Timing Role: Input-protected, wide-VIN DC/DC stage upstream of isolated DC/DC converters and signal conditioning circuitry. Use Value: 42V absolute max rating and built-in overvoltage protection tolerate industrial surge events; 2.5µA IQ extends backup battery runtime during mains failure. |
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#PBF | Lacks forced continuous mode; defaults to pulse-skipping operation when SYNC/MODE is floating. | Higher light-load ripple and variable frequency-less suitable for noise-sensitive RF or imaging systems. | Select LT8640JUDCF#PBF only if Burst Mode or pulse-skipping suffices and FCM is not required. |
| LM61480QRVFRQ1 | Texas Instruments' AEC-Q100 42V, 8A buck with 15µA IQ and fixed 2.1MHz frequency-no spread spectrum or side-wettable QFN. | Higher IQ increases standby power; fixed frequency may require filtering to meet CISPR 25; no AOI-friendly package. | Choose LM61480QRVFRQ1 only if higher current (8A) is needed and EMI margin allows fixed-frequency operation. |
Compared with LT8640JUDCF#PBF, the LT8640JUDCF-1#PBF adds forced continuous mode for deterministic frequency and faster transients, while LM61480QRVFRQ1 trades EMI performance and manufacturability for higher current and TI's ecosystem support.
Availability
LT8640JUDCF-1#PBF is available at Aetrix Electronics and suitable for automotive infotainment, ADAS camera modules, industrial PLCs, and GSM base station power supplies requiring stable component supply, AEC-Q100 qualification, and long-term lifecycle assurance.
Supply support for LT8640JUDCF-1#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/LT8640-1 product line was designed specifically for automotive and industrial applications demanding ultra-low EMI, high efficiency across wide load ranges, and extended temperature operation-leveraging Silent Switcher architecture and robust packaging.
FAQ
What is the maximum junction temperature rating for LT8640JUDCF-1#PBF?
The LT8640JUDCF-1#PBF is rated for a maximum junction temperature of +150°C and is qualified per AEC-Q100 Grade 1. This rating is validated across its full operating range (–40°C to +150°C), enabling deployment in engine bay and powertrain locations where ambient temperatures exceed 125°C. Derating applies above 125°C junction temperature per Analog Devices' lifetime models.
How does LT8640JUDCF-1#PBF differ from LT8640JUDCF#PBF in operating mode behavior?
The LT8640JUDCF-1#PBF defaults to Forced Continuous Mode (FCM) when the SYNC/MODE pin is left floating, enabling stable switching frequency and negative inductor current for superior transient response. In contrast, LT8640JUDCF#PBF enters pulse-skipping mode under the same condition-causing variable frequency and higher light-load ripple. Both share identical pinout, package, and thermal specs.
Can LT8640JUDCF-1#PBF operate with input voltage below 3.4V?
No. The LT8640JUDCF-1#PBF has a minimum input voltage specification of 3.4V, as confirmed in the Absolute Maximum Ratings and Electrical Characteristics tables. Operation below this threshold is not guaranteed and may result in regulation loss, erratic switching, or failure to start. For sub-3.4V applications, consider the LT8648S or LT3905 families.
What is the purpose of the side-wettable QFN package used in LT8640JUDCF-1#PBF?
The side-wettable QFN (SWQFN) package of LT8640JUDCF-1#PBF exposes solderable sidewalls on all 18 leads, enabling automated optical inspection (AOI) of solder joint quality during SMT assembly. This feature is critical for automotive manufacturing, where zero-defect soldering is mandated, and improves long-term field reliability by verifying interconnect integrity before burn-in or shipment.
Does LT8640JUDCF-1#PBF support spread spectrum modulation, and how is it enabled?
Yes, LT8640JUDCF-1#PBF supports spread spectrum modulation to reduce peak EMI emissions. It is enabled by connecting the SYNC/MODE pin to INTVCC (~3.4V) or an external 3V–4V supply. In this configuration, the oscillator frequency is modulated ±20% around its nominal value (e.g., 2MHz → 1.6–2.4MHz), lowering radiated and conducted EMI without affecting regulation performance.
LT8640JUDCF-1#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)
LT8640JUDCF-1#PBF FAQ
1.How can I place an order for LT8640JUDCF-1#PBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LT8640JUDCF-1#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-1#PBF reliable?
The price and inventory of LT8640JUDCF-1#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-1#PBF is usually 5 days.
3.What payment methods are accepted for LT8640JUDCF-1#PBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LT8640JUDCF-1#PBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LT8640JUDCF-1#PBF?
LT8640JUDCF-1#PBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LT8640JUDCF-1#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-1#PBF?
For technical support, including LT8640JUDCF-1#PBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LT8640JUDCF-1#PBF requirements.
6.How does Aetrix verify that LT8640JUDCF-1#PBF is sourced from the original manufacturer or authorized distributors?
All LT8640JUDCF-1#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-1#PBF meets industry standards.
7.What is the process for return or replacement of LT8640JUDCF-1#PBF?
All LT8640JUDCF-1#PBF units undergo pre-shipment inspection (PSI). If there is an issue with LT8640JUDCF-1#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-1#PBF part is unused and in its original packaging.
Return procedure for LT8640JUDCF-1#PBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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