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Analog Devices Inc. LT8640IUDCF-1#TRPBF
- Part No.:
- LT8640IUDCF-1#TRPBF
- Manufacturer:
- Analog Devices Inc.
- Package:
- 20-WFQFN, 18 Leads, Exposed Pad
- Datasheet:
-
LT8640IUDCF-1#TRPBF.pdf
- Description:
- IC REG BUCK ADJ 5A 20QFN
- Quantity:
- Payment:
- Shipping:
Inventory:2,454
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Product details
Overview
LT8640IUDCF-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 side-wettable 18-lead QFN (3mm × 4mm) package rated for –40°C to 125°C junction temperature. It delivers up to 96% efficiency at 1MHz (12VIN → 5VOUT) and supports automotive-grade power supplies requiring low EMI and fast transient response.
For engineers reviewing the LT8640IUDCF-1#TRPBF datasheet, LT8640IUDCF-1#TRPBF pinout, LT8640IUDCF-1#TRPBF application, or LT8640IUDCF-1#TRPBF equivalent, key selection criteria include ultralow IQ regulation, FCM vs. Burst Mode trade-offs, spread spectrum EMI reduction capability, thermal performance under 7A pulsed load, and compatibility with 3.3V–25V BIAS supply routing.
Technical Context
The LT8640IUDCF-1#TRPBF implements peak current mode control with an internal 0.970V reference and programmable oscillator (200kHz–3MHz via RT resistor). Its forced continuous mode eliminates pulse skipping, enabling consistent switching frequency and improved load-step transient response-critical for noise-sensitive analog rails and real-time control systems.
Silent Switcher architecture integrates dual, matched internal power switches (top NMOS: 67mΩ, bottom NMOS: 28mΩ) with symmetrical layout and integrated bootstrap capacitor path (BST pin + 0.1µF) to minimize high-di/dt loop area. Spread spectrum modulation (±22% frequency deviation) is enabled via SYNC/MODE pin tied to INTVCC, reducing peak radiated emissions by >20dBµV/m per CISPR25 Class 5 testing.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 3.4V to 42V - supports wide-range industrial and automotive battery inputs including cold-crank (4.5V) and load-dump (40V) conditions. |
| Output Current | 5A continuous, 7A peak transient - sustains short-duration overloads without foldback or shutdown, enabling robust power delivery to FPGA I/O banks or motor gate drivers. |
| Quiescent Current | 2.5µA at full regulation - enables >10-year battery life in always-on telematics modules powered from 12V vehicle battery. |
| Switching Frequency | 200kHz to 3MHz (RT-programmable) - allows optimization of inductor size (e.g., 1µH @ 3MHz) and EMI filter footprint while maintaining >95% efficiency at 2MHz. |
| Minimum On-Time | 30ns - enables direct 42VIN → 3.3VOUT conversion at 2MHz without external pre-regulation, reducing BOM count and board space. |
| Feedback Reference | 0.970V ±6mV - provides precise output voltage setting accuracy; line regulation <0.02%/V ensures stable 5.0V rail across 5V–40V input variation. |
| EMI Performance | CISPR25 Class 5 compliant with EMI filter - measured radiated emissions ≤40dBµV/m (horizontal/vertical) at 14VIN→5VOUT/4A/2MHz, eliminating need for ferrite beads or metal shielding. |
Pinout & Package
LT8640IUDCF-1#TRPBF uses an 18-lead, 3mm × 4mm plastic side-wettable QFN package (exposed SW pads on underside) with θJA = 40°C/W and θJC(PAD) = 12°C/W. The side-wettable leads enable automated optical inspection (AOI) of solder joints, critical for automotive AEC-Q100-compliant assembly.
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| BIAS (1) | Internal regulator auxiliary supply | Accepts 3.3V–25V input to reduce VIN current draw; must be bypassed with 1µF ceramic if not tied to VOUT. |
| INTVCC (2) | Internal 3.4V LDO output | Powers control circuitry; requires ≥1µF low-ESR ceramic bypass to GND; no external loading permitted. |
| BST (3) | Bootstrap gate drive supply | Connects to 0.1µF capacitor between BST and SW to generate >VIN gate voltage for top NMOS switch. |
| VIN1/VIN2 (4,13) | Main input power inputs | Each requires dedicated 1µF ceramic bypass to respective GND1/GND2; shared bulk cap connects both to GND. |
| GND1/GND2 (6,7,10,11) | Power switch return paths | Must be tied together and connected to low-impedance ground plane; input capacitor negative terminals placed adjacent to these pins. |
| SW (8,9,21,22) | Switch node outputs | Exposed pads (21,22) must be soldered to SW trace for thermal conduction; SW pins connect to inductor and BST cap. |
| EN/UV (14) | Enable and input undervoltage lockout | Hysteretic threshold (1.00V rise / 0.96V fall); resistor divider from VIN sets custom UVLO point. |
| RT (15) | Oscillator frequency programming | Resistor to GND sets fSW: 221kΩ → 210kHz, 60.4kΩ → 700kHz, 18.2kΩ → 2.00MHz. |
| TR/SS (16) | Soft-start and output tracking | 1.9µA internal current source charges external capacitor; voltage <0.97V forces FB tracking. |
| SYNC/MODE (17) | Operating mode selection | Ground = Burst Mode; float = Forced Continuous Mode (FCM); INTVCC = FCM + spread spectrum; external clock = sync to external source. |
| GND (18) | System ground reference | Connects to system ground plane; separate from GND1/GND2 but electrically tied in PCB layout. |
| PG (19) | Power good open-drain output | Active-high when FB is within ±8% of 0.970V and no fault; pulls low during startup, UVLO, or overtemperature. |
| FB (20) | Feedback voltage sense | Regulated to 0.970V; connect resistor divider tap here; add 4.7pF–22pF phase-lead capacitor from FB to VOUT. |
Key Features
| Feature | Design Value |
|---|---|
| Forced Continuous Mode (FCM) | Enables zero-current-crossing operation across full 0–5A load range, delivering <100ns load-step response time and eliminating audible switching noise in audio subsystems. |
| Silent Switcher Architecture | Dual, symmetric power switch layout with integrated bootstrap path reduces high-frequency EMI by >30dB compared to conventional buck regulators, meeting CISPR25 Class 5 without shielding. |
| Side-Wettable QFN Package | Facilitates AOI-capable solder joint inspection for automotive production lines, ensuring reliability in AEC-Q100 Grade I (–40°C to 125°C) applications. |
| Ultralow 2.5µA Quiescent Current | Maintains full output regulation at microamp loads-enabling always-on CAN transceiver bias rails and low-power sensor hubs without secondary LDOs. |
| Spread Spectrum Modulation | ±22% triangular frequency dithering spreads EMI energy across 3MHz bandwidth, lowering peak emissions to meet stringent automotive EMC requirements. |
Applications
| Automotive Infotainment Power | Industrial PLC I/O Module |
|---|---|
Use Scenario: Powering 5V/3A display interface and USB-C PD controller in head unit with 9–16V battery input and strict CISPR25 Class 5 radiated emission limits. IC Role / Device Role / Timing Role: Primary 42V-input synchronous buck converter operating in forced continuous mode with spread spectrum to suppress EMI near AM/FM antennas. Use Value: Eliminates need for external EMI filters and metal shields, reducing BOM cost by $0.42 and saving 120mm² PCB area versus legacy solutions. | Use Scenario: Generating isolated 5V/2A logic rail for digital I/O expansion cards in modular PLC chassis with 24VDC field bus input. IC Role / Device Role / Timing Role: High-efficiency, thermally robust DC/DC stage delivering regulated 5V under 7A pulsed load transients during solenoid actuation. Use Value: Sustains 80°C case temperature rise at full load without derating, enabling fanless enclosure design and extending MTBF beyond 100,000 hours. |
| Medical Point-of-Care Monitor | Telecom Remote Radio Unit |
Use Scenario: Supplying 3.3V/1.5A analog front-end (AFE) and ADC reference rail in portable ultrasound device powered from Li-ion battery (3.0–4.2V) with backup 12V adapter. IC Role / Device Role / Timing Role: Wide-input buck converter operating in Burst Mode at standby (<100µA load) and FCM during imaging bursts, minimizing self-heating in sealed enclosure. Use Value: Achieves 2.5µA IQ at 3.3VOUT, extending battery runtime to 14 hours-3.2× longer than comparable 10µA IQ regulators. | Use Scenario: Providing 5V/4A bias to GaN PA stages and clock distribution ICs in outdoor 5G RRUs exposed to –40°C to +85°C ambient with 48V PoE input. IC Role / Device Role / Timing Role: Automotive-grade buck regulator with AEC-Q100 qualification, operating at 2MHz to minimize inductor size and support high-density RF module layout. Use Value: Delivers 95.2% efficiency at 48VIN→5VOUT/4A/2MHz, reducing thermal dissipation by 1.8W versus 92% efficient alternatives and avoiding active cooling. |
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 |
|---|---|---|---|
| LT8645S-1#TRPBF | Same FCM operation, 8A continuous rating, 40V max input, 2.2µA IQ, side-wettable 24-lead QFN (4mm × 5mm). | Higher current capability and lower IQ suit 5G baseband processor core rails; larger package requires PCB redesign. | Select when >5A output or sub-2.5µA IQ is required; not drop-in compatible due to pin count and layout. |
| TPS54560QDGQRQ1 | 42V, 5A automotive buck; 15µA IQ in Eco-mode; 3.5µs min on-time; SOIC-8 package; no spread spectrum or Silent Switcher. | Lacks EMI suppression features; higher IQ increases battery drain; SOIC-8 thermal resistance limits high-load operation. | Choose for cost-sensitive non-EMI-critical designs where board space permits larger thermal pad; verify CISPR25 compliance with added filtering. |
Compared with LT8640IUDCF-1#TRPBF, LT8645S-1#TRPBF offers higher current and lower IQ but requires PCB rework, while TPS54560QDGQRQ1 provides pin-compatible SOIC-8 fit but sacrifices EMI performance and light-load efficiency-making LT8640IUDCF-1#TRPBF optimal for space-constrained, EMI-sensitive automotive and industrial applications.
Availability
LT8640IUDCF-1#TRPBF is available at Aetrix Electronics and suitable for automotive infotainment systems, industrial PLC I/O modules, and medical point-of-care monitors requiring stable component supply, AEC-Q100 qualification, and guaranteed long-term availability.
Supply support for LT8640IUDCF-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 precision instrumentation, industrial automation, communications, and automotive markets.
The LT8640/LT8640-1 product line was designed specifically for automotive and industrial power conversion applications demanding ultra-low EMI, high efficiency across wide load ranges, and robust operation in harsh electrical environments.
FAQ
What is the maximum junction temperature rating for LT8640IUDCF-1#TRPBF?
The LT8640IUDCF-1#TRPBF is rated for operation from –40°C to 125°C junction temperature. This Grade I specification meets AEC-Q100 requirements for automotive cabin and industrial control applications. Thermal derating begins above 125°C, and overtemperature protection activates at 150°C to prevent permanent damage. The side-wettable QFN package achieves θJA = 40°C/W, enabling reliable 5A operation with standard 2oz copper PCB layout.
How does the SYNC/MODE pin configure forced continuous mode on LT8640IUDCF-1#TRPBF?
On LT8640IUDCF-1#TRPBF, forcing the SYNC/MODE pin to float (high-impedance, leakage <1µA) configures forced continuous mode (FCM). In this state, the regulator maintains constant switching frequency across 0–5A load, enabling fast transient response and eliminating low-frequency output ripple. Pulling SYNC/MODE low enables Burst Mode for ultralow IQ, while tying it to INTVCC adds spread spectrum modulation to FCM for EMI reduction.
Can LT8640IUDCF-1#TRPBF operate with a 3.3V input voltage?
No, LT8640IUDCF-1#TRPBF requires a minimum input voltage of 3.4V per absolute maximum ratings and electrical characteristics tables. At 3.3V input, the internal UVLO circuit prevents startup, and regulation cannot be maintained. For 3.0–4.2V battery-powered applications, consider using LT8640IUDCF-1#TRPBF with a 5V boost pre-regulator or selecting a lower-VIN alternative like LT8614.
What is the purpose of the side-wettable leads on the LT8640IUDCF-1#TRPBF package?
The side-wettable leads on LT8640IUDCF-1#TRPBF enable automated optical inspection (AOI) of solder fillets during SMT assembly-a critical requirement for AEC-Q100 automotive manufacturing. Unlike standard QFN packages, the exposed vertical lead surfaces reflect machine vision lighting, allowing 100% solder joint quality verification without X-ray. This improves first-pass yield and long-term field reliability in vibration-prone automotive environments.
Does LT8640IUDCF-1#TRPBF support output voltage tracking during power-up?
Yes, LT8640IUDCF-1#TRPBF supports output voltage tracking via the TR/SS pin. When TR/SS voltage is below 0.97V, the FB pin is regulated to match TR/SS voltage, enabling precise sequencing with other rails. An internal 1.9µA current source charges an external capacitor on TR/SS to program soft-start slew rate. This feature is essential for FPGAs and multi-rail processors requiring controlled power-up order to prevent latch-up or inrush damage.
LT8640IUDCF-1#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)
LT8640IUDCF-1#TRPBF FAQ
1.How can I place an order for LT8640IUDCF-1#TRPBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LT8640IUDCF-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 LT8640IUDCF-1#TRPBF reliable?
The price and inventory of LT8640IUDCF-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 LT8640IUDCF-1#TRPBF is usually 5 days.
3.What payment methods are accepted for LT8640IUDCF-1#TRPBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LT8640IUDCF-1#TRPBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LT8640IUDCF-1#TRPBF?
LT8640IUDCF-1#TRPBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LT8640IUDCF-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 LT8640IUDCF-1#TRPBF?
For technical support, including LT8640IUDCF-1#TRPBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LT8640IUDCF-1#TRPBF requirements.
6.How does Aetrix verify that LT8640IUDCF-1#TRPBF is sourced from the original manufacturer or authorized distributors?
All LT8640IUDCF-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 LT8640IUDCF-1#TRPBF meets industry standards.
7.What is the process for return or replacement of LT8640IUDCF-1#TRPBF?
All LT8640IUDCF-1#TRPBF units undergo pre-shipment inspection (PSI). If there is an issue with LT8640IUDCF-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 LT8640IUDCF-1#TRPBF part is unused and in its original packaging.
Return procedure for LT8640IUDCF-1#TRPBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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