LT8640A

42V, 5A/8A Peak Synchronous Step-Down Silent Switcher with 2.5μA Quiescent Current

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New Content (2)

Books & eBooks

Understanding Silent Switcher Technology: High Efficiency, Low EMI eBook

Solutions Bulletins & Brochures

Silent Switcher Technology

Overview

Features and Benefits
Product Details

Features and Benefits

Silent Switcher^® Architecture
- Ultralow EMI Emissions
- Spread Spectrum Frequency Modulation
High Efficiency at High Frequency
- Up to 96% Efficiency at 1MHz, 12V_IN to 5V_OUT
- Up to 95% Efficiency at 2MHz, 12V_IN to 5V_OUT
Wide Input Voltage Range: 3.4V to 42V
5A Maximum Continuous, 8A Peak Transient Output
Ultralow Quiescent Current Burst Mode^® Operation
- 2.5μA IQ Regulating 12V_IN to 3.3V_OUT
- Output Ripple < 10mV_P-P

Fast Minimum Switch On-Time: 30ns
Low Dropout Under All Conditions: 100mV at 1A
Available in Fixed 3.3V Output
Forced Continuous Mode
Safely Tolerates High Reverse Current
Adjustable and Synchronizable: 200kHz to 3MHz
Peak Current Mode Operation
Output Soft-Start and Tracking
Small 18-Lead 3mm × 4mm Side Solderable QFN with Improved Solder Joint Reliability
AEC-Q100 Qualified for Automotive Applications

Product Details

The LT8640A step-down regulator features Silent Switcher architecture designed to minimize EMI emissions while delivering high efficiency at frequencies up to 3MHz. An ultralow 2.5μA quiescent current—with the output in full regulation—enables applications requiring highest efficiency at very small load currents.

The LT8640A allows high V_IN to low V_OUT conversion at high frequency with a fast minimum top switch on-time of 30ns. The SYNC/MODE pin selects between Burst Mode operation, spread spectrum mode, synchronization to an external clock, and forced continuous mode.

APPLICATIONS

Automotive and Industrial Supplies
General Purpose Step-Down

Product Categories

Power Management

Markets and Technologies

Automotive (1)
- Battery Management Systems (BMS)

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Product Lifecycle Recommended for New Designs

This product has been released to the market. The data sheet contains all final specifications and operating conditions. For new designs, ADI recommends utilization of these products.

Evaluation Kits (1)

DC3099A

LT8640A | 42V, 5A (8A Peak) Synchronous Step-Down Silent Switcher with 2.5μA Quiescent Current

DC3099A

View Detailed Evaluation Kit Information

Demonstration circuit 3099A is a 42V, 5A synchronous step-down Silent Switcher^® with spread spectrum frequency modulation featuring the LT8640A. The demo board is designed for 5V output from a 5.7V to 42V input. Meanwhile the LT8640A can operate down to 3.4V inputs. The wide input range allows a variety of input sources, such as automotive batteries and industrial supplies. The LT8640A is a compact, ultralow emission, high efficiency, and high speed synchronous monolithic stepdown switching regulator. The integrated power switches and inclusion of all necessary circuitry reduce the components count and solution size. Special Silent Switcher architecture minimizes EMI emissions. Selectable spread spectrum mode can further improve EMI performance. Ultralow 2.5μA quiescent current in Burst Mode^® operation achieves high efficiency at very light loads. Fast minimum on-time of 30ns enables high V_IN to low V_OUT conversion at high frequency.

The LT8640A switching frequency can be programmed either via oscillator resistor or external clock over a 200kHz to 3MHz range. The default frequency of demo circuit 3099A is 2MHz. The LT8640A SYNC/MODE pin on the demo board is grounded (JP1 at BURST position) by default for low ripple Burst Mode operation. Spread spectrum mode and forced continuous mode can be selected respectively by moving JP1 shunt. To synchronize to an external clock, move JP1 to FCM/SYNC and apply the external clock to the SYNC terminal.

The LT8640A data sheet gives a complete description of the part, operation, and application information. The data sheet must be read in conjunction with this demo manual for demo circuit 3099A. The LT8640A is assembled in a 3mm × 4mm plastic QFN package with exposed pad for low thermal resistance. The layout recommendations for low EMI operation and maximum thermal performance are available in the data sheet section Low EMI PCB Layout and Thermal Considerations and Peak Output Current.

Resources

Documentation & Resources

Data Sheets

LT8640A: 42V, 5A/8A Peak Synchronous Step-Down Silent Switcher with 2.5μA Quiescent Current Data Sheet (Rev. 0)
3/21/2022
PDF

User Guides

DC3099A - Demo Manual (Rev. 0)
7/28/2022
PDF

Webcasts

Improving Switch-Mode Power Supplies Using Noise Cancelling Technology
2/8/2023

Books & eBooks

Understanding Silent Switcher Technology: High Efficiency, Low EMI eBook
7/14/2023
PDF

Solutions Bulletins & Brochures

Silent Switcher Technology
8/15/2023
PDF

Tools & Simulations

LTspice

LTspice® is a powerful, fast and free simulation software, schematic capture and waveform viewer with enhancements and models for improving the simulation of analog circuits.

LTspice downloads and documentation

Models for the following parts are available in LTspice:

LT8640

LT8640-1

LT8640A

LT8640S-2

LTpowerCAD

LTpowerCAD^® is a power supply design program which selects power stage components, provides detailed power efficiency, shows quick loop Bode plot stability and load transient analysis, and can export to LTspice for simulation.

LTpowerCAD download and documentation

Design tools for the following parts are available in LTpowerCAD:

LT8640

LT8640S

Design Resources

ADI has always placed the highest emphasis on delivering products that meet the maximum levels of quality and reliability. We achieve this by incorporating quality and reliability checks in every scope of product and process design, and in the manufacturing process as well. "Zero defects" for shipped products is always our goal.View our quality and reliability program and certifications for more information.

Part Number	Material Declaration	Reliability Data	Pin/Package Drawing	CAD Symbols, Footprints & 3D Models
LT8640AJUDCM#PBF	Material Declaration	Reliability Data	20(18)-Lead Plastic Side Wettable QFN (3mm × 4mm)	Ultra Librarian SamacSys
LT8640AJUDCM#TRPBF	Material Declaration	Reliability Data	20(18)-Lead Plastic Side Wettable QFN (3mm × 4mm)	Ultra Librarian SamacSys
LT8640AJUDCM#WPBF	Material Declaration	Reliability Data	20(18)-Lead Plastic Side Wettable QFN (3mm × 4mm)	Ultra Librarian SamacSys
LT8640AJUDCM#WTRPBF	Material Declaration	Reliability Data	20(18)-Lead Plastic Side Wettable QFN (3mm × 4mm)	Ultra Librarian SamacSys
LT8640AJUDCM-3.3#PBF	Material Declaration	Reliability Data	20(18)-Lead Plastic Side Wettable QFN (3mm × 4mm)	Ultra Librarian SamacSys
LT8640AJUDCM-3.3#TRPBF	Material Declaration	Reliability Data	20(18)-Lead Plastic Side Wettable QFN (3mm × 4mm)	Ultra Librarian SamacSys
LT8640AJUDCM-3.3#WPBF	Material Declaration	Reliability Data	20(18)-Lead Plastic Side Wettable QFN (3mm × 4mm)	Ultra Librarian SamacSys
LT8640AJUDCM-3.3#WTRPBF	Material Declaration	Reliability Data	20(18)-Lead Plastic Side Wettable QFN (3mm × 4mm)	Ultra Librarian SamacSys
Wafer Fabrication Data

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Pricing displayed is based on 1-piece. The USA list pricing shown is for budgetary use only, shown in United States dollars (FOB USA per unit), and is subject to change. International prices may vary due to local duties, taxes, fees and exchange rates.