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Analog Devices Inc. LT8640JUDCF#TRPBF
- Part No.:
- LT8640JUDCF#TRPBF
- Manufacturer:
- Analog Devices Inc.
- Package:
- 20-WFQFN, 18 Leads, Exposed Pad
- Datasheet:
-
LT8640JUDCF#TRPBF.pdf
- Description:
- IC REG BUCK ADJ 5A 20QFN
- Quantity:
- Payment:
- Shipping:
Inventory:1,038
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Product details
Overview
LT8640JUDCF#TRPBF 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 for automotive power supplies requiring ultra-low EMI and high efficiency at light loads.
For engineers reviewing the LT8640JUDCF#TRPBF datasheet, LT8640JUDCF#TRPBF pinout, LT8640JUDCF#TRPBF application, or LT8640JUDCF#TRPBF equivalent, key selection criteria include input voltage range (3.4V–42V), forced continuous mode capability (LT8640-1 variant), thermal grade (–40°C to 150°C junction), and spread spectrum EMI reduction.
Technical Context
The LT8640JUDCF#TRPBF implements peak current mode control with an internal 0.970V reference and supports programmable switching frequency from 200kHz to 3MHz via RT resistor. Its Silent Switcher architecture uses symmetrical layout and integrated bypass capacitors to suppress radiated EMI without external filters.
It features dual input rails (VIN1/VIN2), dedicated BIAS pin for efficiency optimization at VOUT ≥ 3.3V, and SYNC/MODE pin enabling four operating modes: Burst Mode (2.5µA IQ), pulse-skipping (LT8640), forced continuous mode (LT8640-1), or external clock synchronization - all with spread spectrum option.
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 (≤42V). |
| Output Current | 5A continuous, 7A peak - sustains transient loads without dropout in industrial and automotive systems. |
| Quiescent Current | 2.5µA in regulation - enables always-on subsystems (e.g., CAN wake-up receivers) with multi-year battery life. |
| Min On-Time | 30ns - allows high-frequency, high-VIN-to-low-VOUT conversion (e.g., 42V → 3.3V at 2MHz) without pulse skipping. |
| Switching Frequency | 200kHz–3MHz (RT-programmable) - balances size (small inductors/caps) and efficiency across load conditions. |
| Thermal Grade | –40°C to 150°C junction - qualified for under-hood automotive applications per AEC-Q100 Grade J. |
| EMI Performance | CISPR 25 Class 5 compliant with spread spectrum - eliminates need for external EMI filters in infotainment and ADAS modules. |
Pinout & Package
LT8640JUDCF#TRPBF uses an 18-lead, 3mm × 4mm plastic side-wettable QFN package (LHJK marking) with exposed SW pads (Pins 21, 22) for enhanced thermal dissipation. The package supports automated optical inspection (AOI) of solder joints and meets automotive reflow requirements.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| BIAS (1) | Internal regulator supply | Accepts VOUT (≥3.3V) to reduce VIN current draw and improve light-load efficiency. |
| INTVCC (2) | Internal 3.4V rail bypass | Requires ≥1µF low-ESR ceramic cap; powers control logic and gate drivers. |
| BST (3) | Bootstrap capacitor node | Connects 0.1µF capacitor to enable high-side NMOS gate drive above VIN. |
| VIN1/VIN2 (4,13) | Dual input power inputs | Each requires dedicated 1µF local ceramic bypass; reduces high-frequency input ripple. |
| GND1/GND2 (6,7,10,11) | Power switch return paths | Must be tied together and connected to low-impedance ground plane for EMI control. |
| SW (8,9,21,22) | Power switch output | Exposed pads (21,22) must be soldered to SW trace for thermal performance; critical for EMI loop minimization. |
| EN/UV (14) | Enable & undervoltage lockout | Hysteretic threshold (0.96V/1.00V) enables programmable input UVLO using resistor divider. |
| RT (15) | Frequency programming | Resistor to GND sets fSW from 200kHz to 3MHz; determines inductor size and efficiency trade-off. |
| TR/SS (16) | Soft-start & tracking | 1.9µA internal current source enables controlled VOUT ramp rate; supports power sequencing. |
| SYNC/MODE (17) | Operating mode control | Selects Burst Mode (ground), FCM (float), spread spectrum (3–4V), or sync (external clock). |
| GND (18) | System ground reference | Connects to system ground plane; completes feedback and PG circuit return path. |
| PG (19) | Power good indicator | Open-drain output asserts high when FB is within ±8% of 0.970V and no faults exist. |
| FB (20) | Feedback reference node | Regulated to 0.970V; connects to resistor divider tap and 4.7–22pF phase-lead capacitor. |
Key Features
| Feature | Design Value |
|---|---|
| Silent Switcher® architecture | Integrated symmetric layout and internal bypass caps reduce radiated EMI by >30dB vs conventional buck regulators. |
| Ultralow 2.5µA quiescent current | Enables >10-year battery life in always-on automotive modules (e.g., telematics, body controllers) without compromising regulation. |
| 30ns minimum on-time | Supports direct 42V→3.3V/5V conversion at 2MHz, eliminating intermediate stages and reducing BOM count. |
| AEC-Q100 Grade J qualification | Validated for –40°C to 150°C operation with lifetime reliability data - suitable for engine bay and transmission control units. |
| Forced Continuous Mode (FCM) | Ensures fixed-frequency operation across full 0–5A load range, delivering <50µs load-step response for radar and camera power rails. |
| Spread spectrum modulation | ±20% triangular frequency dithering lowers peak EMI amplitude, easing CISPR 25 Class 5 compliance in crowded RF environments. |
Applications
| Automotive Infotainment Power | ADAS Camera Module Supply |
|---|---|
Use Scenario: Powering SoC, DSP, and display interfaces in head-unit systems with strict EMI limits and cold-crank survival. IC Role / Device Role / Timing Role: Primary 5V/3.3V buck converter delivering regulated power with burst-mode IQ <3µA during standby. Use Value: Eliminates external EMI filter components while maintaining >95% efficiency at 1A and surviving 4.5V cold-crank events. | Use Scenario: Supplying image sensor and ISP in forward-facing cameras requiring fast transient response and low noise. IC Role / Device Role / Timing Role: High-bandwidth FCM-mode buck supplying 1.2V/3.3V rails with <50µs 1A load-step recovery. Use Value: Prevents image corruption during rapid illumination changes by minimizing output voltage deviation (<15mV). |
| Industrial PLC I/O Module | GSM Base Station Bias Supply |
Use Scenario: Providing isolated 5V bias for analog input/output channels in harsh factory environments with wide temperature swings. IC Role / Device Role / Timing Role: Robust 42V-input buck converting to 5V with 150°C junction rating and undervoltage lockout. Use Value: Ensures uninterrupted operation during brownouts and maintains regulation across –40°C to 85°C ambient without derating. | Use Scenario: Generating stable 5V/3.3V rails for RF power amplifiers and baseband processors in cellular infrastructure equipment. IC Role / Device Role / Timing Role: EMI-optimized buck converter synchronized to system clock to avoid spectral interference with LTE/5G bands. Use Value: Enables co-location of digital and RF sections on same PCB by meeting stringent conducted/radiated EMI limits. |
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 |
|---|---|---|---|
| LT8640S-1JUDCF#TRPBF | Same 5A/42V specs but includes internal compensation and soft-start; side-wettable QFN, Grade J. | Reduces external component count (no RT/SS caps needed); identical thermal and EMI performance. | Choose when simplifying design validation and reducing bill-of-materials complexity is prioritized over maximum flexibility. |
| MPQ4433AGL-AEC1-P | 45V/3.5A AEC-Q100 Grade 1 buck; 17µA IQ; no spread spectrum; 3mm × 4mm QFN. | Lacks Silent Switcher EMI suppression; higher IQ limits battery-powered use; lower current rating. | Consider only for cost-sensitive, non-EMI-critical automotive applications where 3.5A output suffices. |
Compared with LT8640S-1JUDCF#TRPBF, the LT8640JUDCF#TRPBF offers full external compensation and RT programming for optimized transient response and frequency tuning, while MPQ4433AGL-AEC1-P provides lower cost at the expense of EMI performance and light-load efficiency.
Availability
LT8640JUDCF#TRPBF is available at Aetrix Electronics and suitable for automotive infotainment, ADAS camera modules, industrial PLC I/O, and GSM base station bias supplies requiring stable component supply, AEC-Q100 qualification, and ultra-low EMI compliance.
Supply support for LT8640JUDCF#TRPBF 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/LT8640-1 product line delivers high-efficiency, low-EMI DC/DC conversion for demanding automotive and industrial applications where reliability, thermal robustness, and electromagnetic compatibility are critical.
FAQ
What is the maximum junction temperature rating for LT8640JUDCF#TRPBF?
The LT8640JUDCF#TRPBF is rated for a maximum junction temperature of 150°C and is AEC-Q100 qualified for Grade J operation. This specification ensures reliable performance in under-hood automotive environments and high-ambient industrial settings. Thermal derating begins above 125°C, and the device incorporates overtemperature protection that activates above 150°C to prevent permanent damage. The θJA is 40°C/W, and θJC(PAD) is 12°C/W for proper thermal design.
Does LT8640JUDCF#TRPBF support forced continuous mode (FCM)?
No - LT8640JUDCF#TRPBF is the standard LT8640 variant and does not support forced continuous mode. It operates in Burst Mode (when SYNC/MODE = GND), pulse-skipping mode (when SYNC/MODE is floating), or spread spectrum/synchronized modes. Forced continuous mode is exclusive to the LT8640-1 family (e.g., LT8640JUDCF-1#TRPBF). Using LT8640JUDCF#TRPBF in FCM applications will result in uncontrolled pulse skipping and degraded transient response.
How is the switching frequency programmed on LT8640JUDCF#TRPBF?
The switching frequency of LT8640JUDCF#TRPBF is set using an external resistor connected between the RT pin (Pin 15) and GND. Typical values range from 221kΩ (210kHz) to 18.2kΩ (2.0MHz), supporting 200kHz–3MHz operation. The relationship is approximately fSW ≈ 1.15×10⁹ / RRT(Ω) kHz. Frequency accuracy is ±10% over temperature and line, and spread spectrum modulation adds ±20% dither around the programmed center frequency.
Can LT8640JUDCF#TRPBF be used with a 3.3V output and 12V input at 2MHz?
Yes - LT8640JUDCF#TRPBF supports 12V-to-3.3V conversion at 2MHz using its 30ns minimum on-time. With RT = 60.4kΩ, it achieves ~2MHz operation, and typical efficiency exceeds 95% at 1A load. Use a 2.2µH inductor and ensure proper layout: minimize SW loop area, place BST and input capacitors close to pins, and connect exposed SW pads (21,22) directly to the inductor node. Efficiency drops slightly below 90% at full 5A due to conduction losses.
What is the purpose of the BIAS pin on LT8640JUDCF#TRPBF?
The BIAS pin on LT8640JUDCF#TRPBF supplies the internal 3.4V regulator, reducing input supply current and improving light-load efficiency. When connected to VOUT (≥3.3V), the IC draws bias current from the output rail instead of VIN, cutting total input current by up to 11mA at full load. For outputs below 3.3V, tie BIAS to GND. Always decouple BIAS with a 1µF ceramic capacitor if driven from an external supply other than VOUT.
LT8640JUDCF#TRPBF 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:
- 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#TRPBF FAQ
1.How can I place an order for LT8640JUDCF#TRPBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LT8640JUDCF#TRPBF 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#TRPBF reliable?
The price and inventory of LT8640JUDCF#TRPBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LT8640JUDCF#TRPBF is usually 5 days.
3.What payment methods are accepted for LT8640JUDCF#TRPBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LT8640JUDCF#TRPBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LT8640JUDCF#TRPBF?
LT8640JUDCF#TRPBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LT8640JUDCF#TRPBF 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#TRPBF?
For technical support, including LT8640JUDCF#TRPBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LT8640JUDCF#TRPBF requirements.
6.How does Aetrix verify that LT8640JUDCF#TRPBF is sourced from the original manufacturer or authorized distributors?
All LT8640JUDCF#TRPBF 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#TRPBF meets industry standards.
7.What is the process for return or replacement of LT8640JUDCF#TRPBF?
All LT8640JUDCF#TRPBF units undergo pre-shipment inspection (PSI). If there is an issue with LT8640JUDCF#TRPBF, 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#TRPBF part is unused and in its original packaging.
Return procedure for LT8640JUDCF#TRPBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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