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Analog Devices Inc. LT8640JUDCF-1#TRPBF
- Part No.:
- LT8640JUDCF-1#TRPBF
- Manufacturer:
- Analog Devices Inc.
- Package:
- 20-WFQFN, 18 Leads, Exposed Pad
- Datasheet:
-
LT8640JUDCF-1#TRPBF.pdf
- Description:
- IC REG BUCK ADJ 5A 20QFN
- Quantity:
- Payment:
- Shipping:
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Product details
Overview
LT8640JUDCF-1#TRPBF 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 in a thermally enhanced side-wettable QFN package.
For engineers reviewing the LT8640JUDCF-1#TRPBF datasheet, LT8640JUDCF-1#TRPBF pinout, LT8640JUDCF-1#TRPBF application, or LT8640JUDCF-1#TRPBF equivalent, key selection criteria include ultralow EMI performance, high-frequency operation up to 3MHz, forced continuous mode transient response, thermal robustness to 150°C junction, and automotive-grade reliability validation.
Technical Context
The LT8640JUDCF-1#TRPBF implements peak current mode control with an internal 0.97V reference and programmable oscillator (200kHz–3MHz via RT resistor). Its Silent Switcher architecture uses dual input paths and integrated bypass capacitors to suppress common-mode EMI.
Unlike the LT8640, this variant exclusively supports forced continuous mode (FCM), enabling negative inductor current and fast load-step response without pulse skipping. The SYNC/MODE pin selects between Burst Mode, FCM, spread spectrum, or external synchronization - all while maintaining full frequency operation across 0–5A output loads.
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 transient loads without foldback or shutdown |
| Quiescent Current | 2.5µA at full regulation - enables always-on systems with multi-year battery life |
| Switching Frequency | 200kHz to 3MHz (RT-programmable) - allows compact magnetics and noise avoidance in sensitive bands |
| Min On-Time | 30ns - enables high VIN-to-low VOUT conversion (e.g., 42V→3.3V) at 2MHz+ |
| EMI Performance | Meets CISPR 25 Class 5 peak limits - validated with EMI filter on DC2202A demo board |
| Junction Temp Range | –40°C to +150°C - qualified per AEC-Q100 Grade J for under-hood automotive use |
Pinout & Package
LT8640JUDCF-1#TRPBF 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 to the switch node. The package supports automated optical inspection (AOI) of solder joints.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| BIAS (1) | Internal regulator bias supply | Reduces VIN current draw when tied to ≥3.1V output (e.g., VOUT); enables >90% efficiency at light loads |
| INTVCC (2) | Internal 3.4V regulator bypass | Requires ≥1µF low-ESR ceramic capacitor; powers gate drivers and control logic |
| BST (3) | Bootstrap voltage supply | Connects to 0.1µF capacitor between BST and SW; enables high-side NMOS drive above VIN |
| VIN1/VIN2 (4,13) | Dual input power inputs | Each requires dedicated 1µF ceramic cap to respective GND1/GND2; minimizes high-di/dt loop area |
| GND1/GND2 (6,7,10,11) | Power switch return paths | Must be tied together and connected to ground plane; forms low-inductance return for bottom FET |
| SW (8,9,21,22) | Switch node outputs | Pins 8/9 are signal SW; pins 21/22 are exposed pad SW - all must connect to same PCB copper |
| EN/UV (14) | Enable and undervoltage lockout | Hysteresis of 40mV; rising threshold = 1.00V - enables programmable input UVLO with resistor divider |
| RT (15) | Oscillator frequency set | Resistor to GND sets fSW: 221kΩ = 210kHz, 60.4kΩ = 700kHz, 18.2kΩ = 2.0MHz |
| TR/SS (16) | Soft-start and tracking | 1.9µA internal current source charges external cap; controls VOUT ramp rate and enables output tracking |
| SYNC/MODE (17) | Operating mode select | Ground = Burst Mode; float = FCM; INTVCC = spread spectrum FCM; external clock = sync FCM |
| GND (18) | System ground reference | Connects to system ground plane; separates signal ground from power ground paths |
| PG (19) | Power good indicator | Open-drain output asserts high when FB is within ±7.5% of 0.97V and no fault exists |
| FB (20) | Feedback voltage sense | Regulates to 0.970V ±0.006V; requires 4.7pF–22pF phase-lead capacitor from FB to VOUT |
Key Features
| Feature | Design Value |
|---|---|
| Silent Switcher® architecture | Dual input paths and integrated bypass caps reduce radiated EMI by >30dB vs conventional buck regulators |
| Forced Continuous Mode (FCM) | Enables zero-crossing detection and negative inductor current for <10µs load-step recovery time |
| Side-wettable QFN (SWQFN) | Enables AOI-compatible solder joint inspection on production lines without X-ray |
| AEC-Q100 Grade J qualification | Validated for –40°C to +150°C operation with HTOL, TC, UHAST, and ESD testing per automotive standards |
| Spread spectrum modulation | ±20% triangular frequency dither reduces peak EMI amplitude without affecting regulation stability |
Applications
| Automotive Infotainment Power | Industrial PLC I/O Module |
|---|---|
Use Scenario: Powering SoC, DDR memory, and display interfaces in head-unit systems with 12V battery input and strict CISPR 25 EMI limits. IC Role / Device Role / Timing Role: Primary 5V/3.3V buck converter delivering regulated rails with burst-mode sleep current <3µA and FCM wake-up response <15µs. Use Value: Eliminates need for external EMI filters while meeting Class 5 radiated limits - reducing BOM cost and board area by 35%. | Use Scenario: Generating isolated 5V logic supply from 24V industrial bus in DIN-rail mounted controllers with ambient temps up to 85°C. IC Role / Device Role / Timing Role: High-efficiency, thermally robust DC/DC stage converting 24V to 5V at 3A continuous, operating in forced continuous mode for sensor interface stability. Use Value: Maintains >92% efficiency at full load and 150°C junction temperature - enabling convection-only cooling in sealed enclosures. |
| GSM Base Station RF Power Amp | Medical Portable Diagnostic Imaging |
Use Scenario: Biasing GaN RF power amplifiers requiring clean, low-noise 28V supply derived from 48V telecom rectifier with minimal conducted EMI. IC Role / Device Role / Timing Role: High-VIN buck controller (48V→28V) operating at 1.5MHz with spread spectrum to avoid interference with LTE band reception. Use Value: Achieves <10mVP-P output ripple and passes EN 55032 Class A conducted emissions without ferrite beads or LC filters. | Use Scenario: Powering FPGA, ADC, and analog front-end in handheld ultrasound devices where battery runtime and EMI immunity are critical. IC Role / Device Role / Timing Role: Dual-output power manager (5V + 3.3V) using TR/SS tracking and soft-start to coordinate rail sequencing during wake-from-sleep. Use Value: Enables 2.5µA quiescent current in standby and <100ms controlled startup - extending single-charge battery life to >72 hours. |
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-1#TRPBF | LQFN package, same FCM capability, but includes internal compensation and reduced pin count (16-pin) | Targeted for space-constrained designs where layout simplicity outweighs thermal performance needs | Select if PCB area is constrained and thermal margin >20°C suffices; not suitable for 150°C ambient |
| MPQ4433AGL-AEC1-Z | Monolithic 42V/3.5A buck with 17µA IQ, no spread spectrum, QFN-16 package, AEC-Q100 Grade 1 (–40°C to +125°C) | Lacks Silent Switcher EMI suppression and forced continuous mode - requires external filtering for automotive EMI compliance | Select only for cost-sensitive non-critical subsystems where EMI filtering is already present and 150°C operation is unnecessary |
Compared with LT8640S-1#TRPBF and MPQ4433AGL-AEC1-Z, the LT8640JUDCF-1#TRPBF provides superior thermal derating (150°C junction), certified CISPR 25 Class 5 radiated emission performance, and deterministic FCM transient response - making it the only option qualified for under-hood automotive power rails requiring zero EMI filter overhead.
Availability
LT8640JUDCF-1#TRPBF is available at Aetrix Electronics and suitable for automotive infotainment, industrial PLC I/O modules, GSM RF power supplies, and medical portable imaging systems requiring stable component supply with AEC-Q100 qualification and long-term lifecycle support.
Supply support for LT8640JUDCF-1#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 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 guaranteed operation at extreme temperatures - with the LT8640JUDCF-1#TRPBF representing the highest thermal grade variant.
FAQ
What is the maximum junction temperature rating for the LT8640JUDCF-1#TRPBF?
The LT8640JUDCF-1#TRPBF is rated for a maximum junction temperature of +150°C and is fully specified and tested across –40°C to +150°C per AEC-Q100 Grade J requirements. This enables direct placement in high-ambient environments such as engine compartments or sealed industrial enclosures without forced air cooling.
How does the LT8640JUDCF-1#TRPBF differ from the standard LT8640JUDCF#TRPBF?
The LT8640JUDCF-1#TRPBF implements forced continuous mode (FCM) exclusively, whereas the LT8640JUDCF#TRPBF uses pulse-skipping mode. FCM enables negative inductor current, faster transient response (<15µs), and consistent switching frequency across all loads - critical for noise-sensitive analog and RF circuits powered from the same rail.
Can the LT8640JUDCF-1#TRPBF operate without an external RT resistor?
No - the LT8640JUDCF-1#TRPBF requires an external resistor from RT (pin 15) to GND to set the switching frequency. The device has no internal default frequency; omitting the RT resistor disables oscillator operation and prevents regulation. Valid RT values range from 18.2kΩ (2.0MHz) to 221kΩ (210kHz).
What is the purpose of the side-wettable QFN (SWQFN) package used in the LT8640JUDCF-1#TRPBF?
The side-wettable QFN package exposes solderable sidewalls on all perimeter leads, enabling automated optical inspection (AOI) of solder fillets during SMT assembly. This eliminates reliance on X-ray for process validation - reducing manufacturing cost and improving first-pass yield in high-reliability automotive and industrial production lines.
Does the LT8640JUDCF-1#TRPBF support output voltage tracking during power-up?
Yes - the TR/SS pin (pin 16) provides precise output voltage tracking and soft-start control. When driven externally below 0.97V, the LT8640JUDCF-1#TRPBF regulates FB to match the TR/SS voltage, enabling coordinated sequencing with other rails. An internal 1.9µA current source also allows simple capacitor-based soft-start timing.
LT8640JUDCF-1#TRPBF Specifications
- Product attributes
- Attribute value
- Manufacturer:
- Analog Devices Inc.
- Series:
- -
- 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):
- 2.9V
- Voltage - Input (Max):
- 42V
- Voltage - Output (Min/Fixed):
- 0.97V
- Voltage - Output (Max):
- 41.58V
- 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#TRPBF FAQ
1.How can I place an order for LT8640JUDCF-1#TRPBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LT8640JUDCF-1#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-1#TRPBF reliable?
The price and inventory of LT8640JUDCF-1#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-1#TRPBF is usually 5 days.
3.What payment methods are accepted for LT8640JUDCF-1#TRPBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LT8640JUDCF-1#TRPBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LT8640JUDCF-1#TRPBF?
LT8640JUDCF-1#TRPBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LT8640JUDCF-1#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-1#TRPBF?
For technical support, including LT8640JUDCF-1#TRPBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LT8640JUDCF-1#TRPBF requirements.
6.How does Aetrix verify that LT8640JUDCF-1#TRPBF is sourced from the original manufacturer or authorized distributors?
All LT8640JUDCF-1#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-1#TRPBF meets industry standards.
7.What is the process for return or replacement of LT8640JUDCF-1#TRPBF?
All LT8640JUDCF-1#TRPBF units undergo pre-shipment inspection (PSI). If there is an issue with LT8640JUDCF-1#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-1#TRPBF part is unused and in its original packaging.
Return procedure for LT8640JUDCF-1#TRPBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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