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Analog Devices Inc. LT8640IUDC#PBF
- Part No.:
- LT8640IUDC#PBF
- Manufacturer:
- Analog Devices Inc.
- Package:
- 20-WFQFN, 18 Leads, Exposed Pad
- Datasheet:
-
LT8640IUDC#PBF.pdf
- Description:
- IC REG BUCK ADJ 5A 20QFN
- Quantity:
- Payment:
- Shipping:
Inventory:8,006
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Product details
Overview
LT8640IUDC#PBF 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 integrated power MOSFETs. It delivers up to 96% efficiency at 1MHz (12VIN→5VOUT) and supports adjustable switching frequency from 200kHz to 3MHz. Used in automotive infotainment power supplies where low EMI and ultra-low IQ are critical.
For engineers reviewing the LT8640IUDC#PBF datasheet, LT8640IUDC#PBF pinout, LT8640IUDC#PBF application, or LT8640IUDC#PBF equivalent, key selection criteria include its Burst Mode® operation for µA-level light-load efficiency, Silent Switcher® architecture for CISPR 25 Class 5 radiated EMI compliance, forced continuous mode capability (via variant), and AEC-Q100 qualification for automotive-grade reliability.
Technical Context
The LT8640IUDC#PBF implements peak current mode control with an internal 0.97V reference and programmable oscillator (RT pin). Its Silent Switcher® architecture uses symmetrical layout and integrated bypass capacitors to suppress common-mode EMI without external filters.
It features dual input rails (VIN1/VIN2), separate ground paths (GND1/GND2), and dedicated SW pins (8, 9, 21, 22) tied to the exposed thermal pad. The SYNC/MODE pin selects between Burst Mode®, pulse-skipping, spread spectrum, or external synchronization - but does not support forced continuous mode (FCM), which is exclusive to the LT8640-1 variant.
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 - enables single-chip 5V/5A rail for ADAS camera modules or infotainment SoCs. |
| Quiescent Current | 2.5µA at full regulation - sustains >10-year battery life in always-on vehicle telematics systems. |
| Switching Frequency | 200kHz–3MHz (RT-programmable) - allows optimization for size (high-freq) or efficiency (low-freq) in space-constrained PCBs. |
| Min On-Time | 30ns - enables high VIN-to-low VOUT conversion (e.g., 24V→3.3V) at 2MHz without pulse skipping. |
| EMI Performance | CISPR 25 Class 5 compliant (radiated & conducted) - eliminates need for external EMI filters in automotive designs. |
| Thermal Rating | –40°C to 125°C junction - qualified for under-hood and dashboard-mounted applications per AEC-Q100 Grade I. |
Pinout & Package
LT8640IUDC#PBF uses an 18-lead 3mm × 4mm plastic QFN package (UDC) with exposed SW pads (21, 22) for thermal management. Pin count and layout match JEDEC MO-220, though pins 5 and 12 are omitted.
| 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; do not load externally - powers gate drivers and control logic. |
| BST (3) | Bootstrap capacitor connection | Requires 0.1µF ceramic capacitor between BST and SW to drive high-side NMOS gate above VIN. |
| VIN1 (4), VIN2 (13) | Dual input power rails | Each requires dedicated 1µF local ceramic bypass; reduces high-frequency input ripple and EMI. |
| GND1 (6,7), GND2 (10,11) | Power switch return paths | Must be tied together and connected to low-impedance ground plane - critical for EMI suppression. |
| SW (8,9,21,22) | Switch node outputs | Exposed pads (21,22) must be soldered to SW trace for thermal performance; keep node area minimal. |
| EN/UV (14) | Enable & undervoltage lockout | Hysteretic threshold (0.96V↓ / 1.00V↑) enables programmable VIN brownout protection via resistor divider. |
| RT (15) | Oscillator frequency programming | Resistor to GND sets fSW: 221kΩ = 210kHz, 60.4kΩ = 700kHz, 18.2kΩ = 2.0MHz - enables precise EMI band avoidance. |
| TR/SS (16) | Soft-start & output tracking | 1.9µA internal current source enables voltage-ramp control; supports power sequencing with other rails. |
| SYNC/MODE (17) | Operating mode selection | Ground = Burst Mode®; float = pulse-skipping; INTVCC-high = spread spectrum; driven = external sync - no FCM support. |
| GND (18) | System ground reference | Connect directly to system ground plane - completes feedback loop for PG and FB accuracy. |
| PG (19) | Power good open-drain output | Asserts high when FB is within ±8% of 0.97V and VIN > 3.4V - used for downstream power sequencing. |
| FB (20) | Feedback voltage sense | Regulates to 0.970V ±0.6%; requires 4.7pF–22pF phase-lead capacitor from FB to VOUT for stability. |
Key Features
| Feature | Design Value |
|---|---|
| Silent Switcher® Architecture | Integrated input capacitors and symmetrical layout reduce radiated EMI by >30dB vs conventional buck regulators - meets CISPR 25 Class 5 without ferrite beads. |
| Ultralow Quiescent Current | 2.5µA IQ in regulation enables >10-year battery standby in always-on automotive modules (e.g., CAN gateway wake-up circuits). |
| 30ns Minimum On-Time | Enables direct 24V→3.3V conversion at 2MHz, eliminating intermediate stages and reducing BOM count in multi-rail systems. |
| Spread Spectrum Modulation | ±20% frequency dithering (e.g., 2MHz → 1.6–2.4MHz) spreads EMI energy across bandwidth - simplifies EMC validation. |
| AEC-Q100 Grade I Qualification | Qualified for –40°C to +125°C operation with lifetime reliability data - approved for front-end automotive power supplies. |
Applications
| Automotive Infotainment | ADAS Camera Power |
|---|---|
|
Use Scenario: Powering 5V/3A display controller and audio DSP in head unit with strict EMI limits. IC Role / Device Role / Timing Role: Primary 12V→5V buck converter with spread spectrum enabled to pass CISPR 25 radiated emissions. Use Value: Eliminates external EMI filter components, saving >$0.35/BOM and 8mm² PCB area while meeting OEM EMC requirements. |
Use Scenario: Generating 3.3V/2A for image sensor and ISP in surround-view camera module. IC Role / Device Role / Timing Role: High-efficiency, low-noise power stage with 30ns min-on-time enabling direct 12V→3.3V conversion. Use Value: Achieves 95% efficiency at 2A/3.3V (12VIN), reducing thermal load in sealed camera housing and extending MTBF. |
| Telematics Control Unit | Industrial IoT Gateway |
|
Use Scenario: Always-on LTE modem power supply requiring <5µA shutdown current and cold-crank survival. IC Role / Device Role / Timing Role: Main 24V→5V converter operating in Burst Mode® with EN/UV monitoring battery voltage. Use Value: 2.5µA IQ extends vehicle battery life during 30-day parking mode; UVLO prevents brownout resets during engine start. |
Use Scenario: 48V→5V conversion for edge AI processor in railway signaling equipment. IC Role / Device Role / Timing Role: Wide-input buck regulator with 42V absolute max rating handling 48V nominal industrial bus. Use Value: Withstands 60V transients per IEC 61000-4-5; 125°C rating ensures reliability in uncooled cabinet environments. |
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 |
|---|---|---|---|
| LT8640-1IUDC#PBF | Supports forced continuous mode (FCM); identical pinout and package; same 2.5µA IQ and Silent Switcher® architecture. | Required for fast transient response in CPU/GPU power rails where output voltage droop must be <1%. | Select LT8640-1IUDC#PBF if load-step response time <10µs is required; otherwise LT8640IUDC#PBF offers lower EMI in Burst Mode®. |
| MPQ4420AGL-A-Z | 45V input, 2A output, 17µA IQ; no spread spectrum; QFN-10 package; lacks AEC-Q100 qualification. | Suitable for cost-sensitive industrial controls where EMI filtering is acceptable and ambient temp ≤105°C. | Choose MPQ4420AGL-A-Z only for non-automotive, non-EMI-critical 2A applications - not drop-in compatible due to pin count and feature set. |
Compared with LT8640-1IUDC#PBF, the LT8640IUDC#PBF trades forced continuous mode for superior EMI performance in Burst Mode®; versus MPQ4420AGL-A-Z, it delivers 7x lower quiescent current, AEC-Q100 qualification, and integrated EMI mitigation - justifying premium cost in automotive designs.
Availability
LT8640IUDC#PBF is available at Aetrix Electronics and suitable for automotive infotainment, ADAS camera power, and telematics control units requiring stable component supply across extended temperature ranges and long production lifecycles.
Supply support for LT8640IUDC#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 automotive, industrial, communications, and healthcare markets.
The LT8640 series belongs to Analog Devices' Silent Switcher® power management portfolio, engineered specifically for automotive and industrial applications demanding ultra-low EMI, high efficiency at light loads, and AEC-Q100 reliability.
FAQ
What is the maximum input voltage rating for the LT8640IUDC#PBF?
The LT8640IUDC#PBF has an absolute maximum input voltage rating of 42V across VIN1 and VIN2 pins. It operates continuously from 3.4V to 42V, making it suitable for 24V and 36V industrial buses as well as automotive 12V/24V systems with load-dump transients. Exceeding 42V risks permanent damage per Absolute Maximum Ratings.
Does the LT8640IUDC#PBF support forced continuous mode (FCM)?
No, the LT8640IUDC#PBF does not support forced continuous mode. FCM is exclusive to the LT8640-1 variant (e.g., LT8640-1IUDC#PBF). The LT8640IUDC#PBF offers Burst Mode®, pulse-skipping, spread spectrum, and external synchronization via the SYNC/MODE pin - but cannot sustain negative inductor current or provide FCM's fast transient response.
How is EMI reduced in the LT8640IUDC#PBF without external filters?
The LT8640IUDC#PBF achieves low EMI through Silent Switcher® architecture: integrated input capacitors minimize high-di/dt loop area, symmetrical copper layout cancels magnetic fields, and optional spread spectrum modulation disperses noise energy. This enables CISPR 25 Class 5 compliance on standard 4-layer PCBs without ferrite beads or common-mode chokes.
What is the purpose of the dual VIN and GND pins on the LT8640IUDC#PBF?
VIN1/VIN2 and GND1/GND2 provide separate high-frequency current paths to minimize ground bounce and EMI. VIN1/GND1 handles one half of the input bypass network; VIN2/GND2 handles the other. Routing them as independent low-inductance loops - with dedicated 1µF ceramics - reduces switching noise injection into shared ground planes.
Can the LT8640IUDC#PBF be synchronized to an external clock?
Yes, the LT8640IUDC#PBF supports external clock synchronization via the SYNC/MODE pin. When driven with a clean CMOS/TTL clock signal (200kHz–3MHz), the device locks its internal oscillator and operates in pulse-skipping mode aligned to the external edge. This enables deterministic EMI placement in systems with multiple synchronized converters.
LT8640IUDC#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
- Supplier Device Package:
- 20-QFN (3x4)
LT8640IUDC#PBF FAQ
1.How can I place an order for LT8640IUDC#PBF through Aetrix?
Please submit a Request for Quotation (RFQ) for LT8640IUDC#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 LT8640IUDC#PBF reliable?
The price and inventory of LT8640IUDC#PBF are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for LT8640IUDC#PBF is usually 5 days.
3.What payment methods are accepted for LT8640IUDC#PBF?
We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for LT8640IUDC#PBF transactions.
Note: Certain payment methods may incur a processing fee.
4.How is shipping managed for LT8640IUDC#PBF?
LT8640IUDC#PBF orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.
Once your LT8640IUDC#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 LT8640IUDC#PBF?
For technical support, including LT8640IUDC#PBF datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your LT8640IUDC#PBF requirements.
6.How does Aetrix verify that LT8640IUDC#PBF is sourced from the original manufacturer or authorized distributors?
All LT8640IUDC#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 LT8640IUDC#PBF meets industry standards.
7.What is the process for return or replacement of LT8640IUDC#PBF?
All LT8640IUDC#PBF units undergo pre-shipment inspection (PSI). If there is an issue with LT8640IUDC#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 LT8640IUDC#PBF part is unused and in its original packaging.
Return procedure for LT8640IUDC#PBF:
1.Submit a request within 90 days.
2.Obtain a Return Material Authorization (RMA) from Aetrix.
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