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Analog Devices Inc. LT8640IUDCF-1#PBF
- Part No.:
- LT8640IUDCF-1#PBF
- Manufacturer:
- Analog Devices Inc.
- Package:
- 20-WFQFN, 18 Leads, Exposed Pad
- Datasheet:
-
LT8640IUDCF-1#PBF.pdf
- Description:
- IC REG BUCK ADJ 5A 20QFN
- Quantity:
- Payment:
- Shipping:
Inventory:402
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Product details
Overview
LT8640IUDCF-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 side-wettable 18-lead 3mm × 4mm QFN package. It delivers up to 96% efficiency at 1MHz (12VIN→5VOUT) and supports automotive-grade operation from –40°C to 125°C junction temperature.
For engineers reviewing the LT8640IUDCF-1#PBF datasheet, LT8640IUDCF-1#PBF pinout, LT8640IUDCF-1#PBF application, or LT8640IUDCF-1#PBF equivalent, key selection criteria include ultralow EMI performance, FCM transient response, input voltage range (3.4V–42V), output accuracy (±1.5% over temp), and thermal robustness in compact layouts.
Technical Context
The LT8640IUDCF-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 -1 variant fixes SYNC/MODE to enable Forced Continuous Mode when floating-eliminating pulse-skipping and ensuring consistent switching frequency across load conditions. This enables fast load-step response (<50µs settling for 1A→2A) and predictable EMI behavior in noise-sensitive applications.
Key Specifications
| Parameter | Value and Actual Design Meaning |
|---|---|
| Input Voltage Range | 3.4V to 42V - supports wide industrial and automotive battery inputs including cold-crank (≥4.5V) and load-dump (≤42V) conditions. |
| Output Current | 5A continuous, 7A peak - sustains high-current loads without derating in thermally optimized layouts using exposed SW pads. |
| Quiescent Current | 2.5µA at full regulation - enables >10-year battery life in always-on systems like telematics or sensor nodes. |
| Switching Frequency | 200kHz to 3MHz (RT-programmable) - allows optimization of size (high-freq) vs. efficiency (low-freq) and avoids AM band interference. |
| Feedback Accuracy | ±1.5% over –40°C to 125°C - ensures stable output under extreme ambient conditions without external trimming. |
| Min On-Time | 30ns - enables high VIN-to-low VOUT conversion (e.g., 42V→3.3V at 2MHz) without duty-cycle limitation. |
| EMI Performance | CISPR 25 Class 5 compliant - meets stringent automotive radiated/conducted emission limits with minimal external filtering. |
Pinout & Package
LT8640IUDCF-1#PBF uses an 18-lead, 3mm × 4mm plastic side-wettable QFN package (LHGX marking) with exposed SW pads (pins 21, 22) for enhanced thermal dissipation and solder joint inspection. The package is RoHS-compliant and qualified per AEC-Q100 Grade I (–40°C to 125°C).
| Pin/Terminal | Circuit Role | Design Meaning |
|---|---|---|
| BIAS (1) | Internal regulator bias supply | Accepts 3.1V–25V input; reduces VIN current draw when tied to VOUT ≥3.3V, improving light-load efficiency. |
| INTVCC (2) | Internal 3.4V LDO output | Bypassed with ≥1µF ceramic capacitor; powers control circuitry and cannot drive external loads. |
| BST (3) | Bootstrap gate drive supply | Requires 0.1µF ceramic capacitor to SW; enables high-side NMOS gate drive above VIN. |
| VIN1/VIN2 (4,13) | Main input power rails | Dual-input pins reduce high-frequency loop inductance; each requires dedicated 1µF local ceramic bypass to respective GND1/GND2. |
| GND1/GND2 (6,7,10,11) | Power switch return paths | Separate ground pins minimize ground bounce; must be tied together and connected to low-impedance ground plane. |
| SW (8,9,21,22) | Switch node outputs | Exposed pads (21,22) must be soldered to PCB SW trace for thermal and EMI performance; pins 8/9 are signal-level SW connections. |
| EN/UV (14) | Enable and undervoltage lockout | Hysteretic threshold (1.00V rise / 0.96V fall); enables input UVLO programming via resistor divider from VIN. |
| RT (15) | Oscillator frequency set | Resistor to GND programs fSW from 200kHz to 3MHz; tolerance directly impacts frequency accuracy (±5%). |
| TR/SS (16) | Soft-start and tracking | 1.9µA internal pull-up enables capacitor-based soft-start; voltage below 0.97V forces FB tracking for sequencing. |
| SYNC/MODE (17) | Operating mode select | Floating = Forced Continuous Mode (FCM); grounded = Burst Mode; high = spread spectrum + FCM; driven = external sync. |
| GND (18) | Signal ground reference | System ground connection point; must be low-impedance path to main ground plane. |
| PG (19) | Power good open-drain | Asserts high when FB is within ±7.5% of 0.970V and no fault; valid only when VIN >3.4V. |
| FB (20) | Feedback voltage sense | Regulated to 0.970V ±1.5%; requires 4.7pF–22pF phase-lead capacitor from FB to VOUT for stability. |
Key Features
| Feature | Design Value |
|---|---|
| Silent Switcher® architecture | Integrated dual-VIN/GND paths and internal bypass caps reduce EMI by >30dB vs. conventional buck regulators, eliminating need for ferrite beads in most designs. |
| Forced Continuous Mode (FCM) | Ensures fixed-frequency operation across 0–5A load range, enabling predictable EMI filtering and fast transient response (<50µs for 1A load step). |
| Ultralow 2.5µA IQ in regulation | Enables multi-year operation from coin cells or supercaps in always-on IoT sensors and automotive standby systems. |
| 30ns minimum on-time | Supports direct 42V→3.3V conversion at 2MHz, reducing solution size versus two-stage architectures. |
| AEC-Q100 Grade I qualification | Validated for automotive applications including infotainment, ADAS camera modules, and body electronics with full temperature range support. |
| Side-wettable QFN (UDCF) | Enables automated optical inspection (AOI) of solder joints on production lines, improving manufacturing yield and field reliability. |
Applications
| Automotive Infotainment Power | Industrial PLC I/O Module |
|---|---|
Use Scenario: Powering SoC cores, DDR memory, and display interfaces in head units with strict CISPR 25 Class 5 EMI limits. IC Role / Device Role / Timing Role: Primary 5V/3.3V buck converter delivering regulated power with <10mVP-P ripple and zero burst-mode noise. Use Value: Eliminates external EMI filters and shielding, reducing BOM cost by $0.35 and PCB area by 120mm². | Use Scenario: Supplying isolated analog front-ends and microcontrollers in DIN-rail mounted controllers operating from 24VDC industrial rails. IC Role / Device Role / Timing Role: High-efficiency, wide-input DC/DC stage converting 18–36V to 5V/3.3V with robust line/load regulation. Use Value: Maintains >92% efficiency at 100mA–5A loads, reducing thermal design complexity and enabling fanless enclosure operation. |
| GSM Base Station RF Power Amp | Medical Portable Diagnostic Device |
Use Scenario: Biasing GaN RF power amplifiers requiring clean, low-noise 28V supply derived from 48V telecom rectifier. IC Role / Device Role / Timing Role: Intermediate 28V buck stage operating at 1.5MHz with spread-spectrum modulation to avoid interfering with LTE bands. Use Value: Achieves <45dBµV/m radiated emissions at 900MHz–2.1GHz, passing EN 55022 Class B without additional shielding. | Use Scenario: Powering ADCs, op-amps, and Bluetooth LE radios in handheld ultrasound and glucose monitors powered by single-cell Li-ion. IC Role / Device Role / Timing Role: Ultra-low-IQ buck converter maintaining 3.3V rail during 10-year shelf life and active sensing cycles. Use Value: Extends battery runtime by 3.2× vs. standard buck ICs, supporting FDA-required 5-year device shelf life. |
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-1#PBF | LQFN package (3mm × 4mm), same FCM capability, but includes internal spread-spectrum clock generator (no external SYNC required). | Preferred where board space is constrained and deterministic EMI reduction is mandatory without external clock routing. | Select LT8640S-1#PBF if spread-spectrum is required and LQFN footprint is acceptable; LT8640IUDCF-1#PBF offers superior thermal performance via side-wettable pads. |
| MPQ4433AGL-AEC1-Z | Monolithic 45V/6A buck with 1.5µA IQ, but lacks Silent Switcher architecture and fails CISPR 25 Class 5 without added filtering. | Suitable for cost-sensitive automotive non-safety systems where EMI margin is relaxed (e.g., HVAC controls). | Choose MPQ4433AGL-AEC1-Z only when EMI requirements are Class 4 or lower; LT8640IUDCF-1#PBF remains necessary for radar, camera, or infotainment systems. |
Compared with LT8640S-1#PBF, LT8640IUDCF-1#PBF provides better thermal resistance (θJC = 12°C/W vs. ~18°C/W) and AOI-compatible solder joints, while MPQ4433AGL-AEC1-Z trades EMI performance for lower unit cost-making LT8640IUDCF-1#PBF the sole choice for high-reliability, noise-critical automotive applications.
Availability
LT8640IUDCF-1#PBF is available at Aetrix Electronics and suitable for automotive infotainment systems, industrial PLCs, and medical portable diagnostics requiring stable component supply, AEC-Q100 compliance, and long-term lifecycle support.
Supply support for LT8640IUDCF-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 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 noise-sensitive, high-reliability power conversion in automotive and industrial environments-emphasizing ultralow EMI, wide input range, and robust thermal performance.
FAQ
What is the maximum junction temperature rating for LT8640IUDCF-1#PBF?
The LT8640IUDCF-1#PBF is rated for operation from –40°C to 125°C junction temperature and is guaranteed across this full range (Grade I). Thermal derating begins above 125°C, and continuous operation beyond 150°C triggers overtemperature protection. The package's θJA is 40°C/W and θJC(PAD) is 12°C/W, enabling reliable 5A operation with proper PCB copper area.
How does LT8640IUDCF-1#PBF differ from LT8640IUDC-1#PBF?
The LT8640IUDCF-1#PBF uses a side-wettable QFN (UDCF) package with exposed SW pads (pins 21, 22) for improved thermal performance and automated optical inspection (AOI) capability. In contrast, LT8640IUDC-1#PBF uses a standard QFN (UDC) without side-wettable leads, limiting solder joint inspection and increasing thermal resistance by ~30%.
Can LT8640IUDCF-1#PBF operate with a 24V input and 3.3V output at 2MHz?
Yes, LT8640IUDCF-1#PBF supports 24V→3.3V conversion at 2MHz using its 30ns minimum on-time. With RT = 60.4kΩ, fSW ≈ 2MHz; efficiency exceeds 93% at 2A load. Layout must minimize SW node area and use tight VIN/GND1/GND2 loops to maintain EMI performance.
What is the purpose of the BIAS pin on LT8640IUDCF-1#PBF?
The BIAS pin on LT8640IUDCF-1#PBF supplies current to the internal 3.4V regulator. When tied to VOUT (≥3.3V), it reduces input supply current and improves light-load efficiency. If VOUT <3.3V or unavailable, BIAS must be tied to GND or a ≥3.1V external supply with 1µF bypass capacitance.
Does LT8640IUDCF-1#PBF support output voltage tracking during power-up?
Yes, LT8640IUDCF-1#PBF supports output voltage tracking via the TR/SS pin. Applying a ramp voltage to TR/SS (e.g., via RC network) forces FB to follow that voltage until it exceeds 0.97V, enabling precise sequencing with other rails. Internal 1.9µA pull-up current simplifies soft-start implementation with a single capacitor.
LT8640IUDCF-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 ~ 125°C (TJ)
- Grade:
- -
- Qualification:
- -
- Mounting Type:
- Surface Mount, Wettable Flank
- Supplier Device Package:
- 20-QFN (3x4)
LT8640IUDCF-1#PBF FAQ
1.How can I place an order for LT8640IUDCF-1#PBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LT8640IUDCF-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 LT8640IUDCF-1#PBF reliable?
The price and inventory of LT8640IUDCF-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 LT8640IUDCF-1#PBF is usually 5 days.
3.What payment methods are accepted for LT8640IUDCF-1#PBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LT8640IUDCF-1#PBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LT8640IUDCF-1#PBF?
LT8640IUDCF-1#PBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LT8640IUDCF-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 LT8640IUDCF-1#PBF?
For technical support, including LT8640IUDCF-1#PBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LT8640IUDCF-1#PBF requirements.
6.How does Aetrix verify that LT8640IUDCF-1#PBF is sourced from the original manufacturer or authorized distributors?
All LT8640IUDCF-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 LT8640IUDCF-1#PBF meets industry standards.
7.What is the process for return or replacement of LT8640IUDCF-1#PBF?
All LT8640IUDCF-1#PBF units undergo pre-shipment inspection (PSI). If there is an issue with LT8640IUDCF-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 LT8640IUDCF-1#PBF part is unused and in its original packaging.
Return procedure for LT8640IUDCF-1#PBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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