LT8640
LT8640-1

RECOMMENDED FOR NEW DESIGNS

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

Data Sheet (Rev. G) Product Selection Table

Part Models: 30
1ku List Price: Starting From $6.49

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Overview

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 Output, 7A Peak Transient Output
Ultralow Quiescent Current Burst Mode^® Operation
- 2.5µA I_Q 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
Forced Continuous Mode (LT8640-1 Only)
Safely Tolerates Inductor Saturation in Overload
Adjustable and Synchronizable: 200kHz to 3MHz
Peak Current Mode Operation
Output Soft-Start and Tracking
Small 18-Lead 3mm × 4mm QFN and Side Wettable QFN
AEC-Q100 Qualified for Automotive Applications

The LT8640/LT8640-1 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 LT8640/LT8640-1 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 either pulse-skipping (LT8640) or forced continuous mode (LT8640-1).


	Package	SYNC/MODE ≠ 0	V_C COMP	H-GRADE	CLKOUT	INTERNAL CAPS
LT8640	QFN	Pulse-Skipping	Internal	Yes	No	No
LT8640-1	QFN	FCM	Internal	Yes	No	No
LT8640S	LQFN	FCM	Internal	No	Yes	Yes
LT8643S	LQFN	FCM	External	No	Yes	Yes
LT8640S-2	LQFN	FCM	Internal	Yes	Yes	No
LT8643S-2	LQFN	FCM	External	Yes	Yes	No

Applications

Automotive and Industrial Supplies
General Purpose Step-Down
GSM Power Supplies

Part Models: 30
1ku List Price: Starting From $6.49

Documentation

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 Model	Pin/Package Drawing	Documentation	CAD Symbols, Footprints, and 3D Models
LT8640EUDC#PBF	20(18)-Lead QFN (3mm x 4mm x 0.75mm w/ EP)	Material Declaration Reliability Report Package Resources	Ultra Librarian SamacSys
LT8640EUDC#TRPBF	20(18)-Lead QFN (3mm x 4mm x 0.75mm w/ EP)	Material Declaration Reliability Report Package Resources	Ultra Librarian SamacSys
LT8640EUDC-1#PBF	20(18)-Lead QFN (3mm x 4mm x 0.75mm w/ EP)	Material Declaration Reliability Report Package Resources	Ultra Librarian SamacSys
LT8640EUDC-1#TRPBF	20(18)-Lead QFN (3mm x 4mm x 0.75mm w/ EP)	Material Declaration Reliability Report Package Resources	Ultra Librarian SamacSys
LT8640EUDCF#PBF	20(18)-Lead Plastic Side Wettable QFN (3mm × 4mm)	Material Declaration Reliability Report Package Resources	Ultra Librarian SamacSys
LT8640EUDCF#TRPBF	20(18)-Lead Plastic Side Wettable QFN (3mm × 4mm)	Material Declaration Reliability Report Package Resources	Ultra Librarian SamacSys
LT8640EUDCF-1#PBF	20(18)-Lead Plastic Side Wettable QFN (3mm × 4mm)	Material Declaration Reliability Report Package Resources	Ultra Librarian SamacSys
LT8640EUDCF-1#TRPBF	20(18)-Lead Plastic Side Wettable QFN (3mm × 4mm)	Material Declaration Reliability Report Package Resources	Ultra Librarian SamacSys
LT8640HUDC#PBF	20(18)-Lead QFN (3mm x 4mm x 0.75mm w/ EP)	Material Declaration Reliability Report Package Resources	Ultra Librarian SamacSys
LT8640HUDC#TRPBF	20(18)-Lead QFN (3mm x 4mm x 0.75mm w/ EP)	Material Declaration Reliability Report Package Resources	Ultra Librarian SamacSys
LT8640HUDC-1#PBF	20(18)-Lead QFN (3mm x 4mm x 0.75mm w/ EP)	Material Declaration Reliability Report Package Resources	Ultra Librarian SamacSys
LT8640HUDC-1#TRPBF	20(18)-Lead QFN (3mm x 4mm x 0.75mm w/ EP)	Material Declaration Reliability Report Package Resources	Ultra Librarian SamacSys
LT8640HUDCF#PBF	20(18)-Lead Plastic Side Wettable QFN (3mm × 4mm)	Material Declaration Reliability Report Package Resources	Ultra Librarian SamacSys
LT8640HUDCF#TRPBF	20(18)-Lead Plastic Side Wettable QFN (3mm × 4mm)	Material Declaration Reliability Report Package Resources	Ultra Librarian SamacSys
LT8640IUDC#PBF	20(18)-Lead QFN (3mm x 4mm x 0.75mm w/ EP)	Material Declaration Reliability Report Package Resources	Ultra Librarian SamacSys
LT8640IUDC#TRPBF	20(18)-Lead QFN (3mm x 4mm x 0.75mm w/ EP)	Material Declaration Reliability Report Package Resources	Ultra Librarian SamacSys
LT8640IUDC-1#PBF	20(18)-Lead QFN (3mm x 4mm x 0.75mm w/ EP)	Material Declaration Reliability Report Package Resources	Ultra Librarian SamacSys
LT8640IUDC-1#TRPBF	20(18)-Lead QFN (3mm x 4mm x 0.75mm w/ EP)	Material Declaration Reliability Report Package Resources	Ultra Librarian SamacSys
LT8640IUDCF#PBF	20(18)-Lead Plastic Side Wettable QFN (3mm × 4mm)	Material Declaration Reliability Report Package Resources	Ultra Librarian SamacSys
LT8640IUDCF#TRPBF	20(18)-Lead Plastic Side Wettable QFN (3mm × 4mm)	Material Declaration Reliability Report Package Resources	Ultra Librarian SamacSys
LT8640IUDCF-1#PBF	20(18)-Lead Plastic Side Wettable QFN (3mm × 4mm)	Material Declaration Reliability Report Package Resources	Ultra Librarian SamacSys
LT8640IUDCF-1#TRPBF	20(18)-Lead Plastic Side Wettable QFN (3mm × 4mm)	Material Declaration Reliability Report Package Resources	Ultra Librarian SamacSys
LT8640JUDCF#PBF	20(18)-Lead Plastic Side Wettable QFN (3mm × 4mm)	Material Declaration Reliability Report Package Resources	Ultra Librarian SamacSys
LT8640JUDCF#TRPBF	20(18)-Lead Plastic Side Wettable QFN (3mm × 4mm)	Material Declaration Reliability Report Package Resources	Ultra Librarian SamacSys
LT8640JUDCF#WPBF	20(18)-Lead Plastic Side Wettable QFN (3mm × 4mm)	Material Declaration Reliability Report Package Resources	Ultra Librarian SamacSys
LT8640JUDCF#WTRPBF	20(18)-Lead Plastic Side Wettable QFN (3mm × 4mm)	Material Declaration Reliability Report Package Resources	Ultra Librarian SamacSys
LT8640JUDCF-1#PBF	20(18)-Lead Plastic Side Wettable QFN (3mm × 4mm)	Material Declaration Reliability Report Package Resources	Ultra Librarian SamacSys
LT8640JUDCF-1#TRPBF	20(18)-Lead Plastic Side Wettable QFN (3mm × 4mm)	Material Declaration Reliability Report Package Resources	Ultra Librarian SamacSys
LT8640JUDCF-1#WPBF	20(18)-Lead Plastic Side Wettable QFN (3mm × 4mm)	Material Declaration Reliability Report Package Resources	Ultra Librarian SamacSys
LT8640JUDCF-1#WTRPBF	20(18)-Lead Plastic Side Wettable QFN (3mm × 4mm)	Material Declaration Reliability Report Package Resources	Ultra Librarian SamacSys

Part Models	Product Lifecycle	PCN

Sep 30, 2020 - 20_0293 Test Site Transfer from Analog Devices Singapore to UTAC Thailand
		PCN20_0293_Form Material_Report Delta Qualification Matrix Qualification Results Summary Test Correlation Report Test Correlation Report Other Qualification Results Summary
LT8640EUDC#PBF	PRODUCTION
LT8640EUDC#TRPBF	PRODUCTION
LT8640EUDCF#PBF	PRODUCTION
LT8640EUDCF#TRPBF	PRODUCTION
LT8640HUDC#PBF	PRODUCTION
LT8640HUDC#TRPBF	PRODUCTION
LT8640HUDCF#PBF	PRODUCTION
LT8640HUDCF#TRPBF	PRODUCTION
LT8640IUDC#PBF	PRODUCTION
LT8640IUDC#TRPBF	PRODUCTION
LT8640IUDCF#PBF	PRODUCTION
LT8640IUDCF#TRPBF	PRODUCTION
LT8640JUDCF#PBF	PRODUCTION
LT8640JUDCF#TRPBF	PRODUCTION

This is the most up-to-date revision of the Data Sheet.

Software Resources

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Hardware Ecosystem

Parts	Product Life Cycle	Description
Hot Swap Controllers 1
LTC4364	RECOMMENDED FOR NEW DESIGNS	Surge Stopper with Ideal Diode

Parts	Product Life Cycle	Description
LT8614	PRODUCTION	42V, 4A Synchronous Step-Down Silent Switcher with 2.5μA Quiescent Current
LT8640S/LT8640SA	RECOMMENDED FOR NEW DESIGNS	42V, 6A Synchronous Step-Down Silent Switcher 2 with 2.5μA Quiescent Current
LT8641	RECOMMENDED FOR NEW DESIGNS	65V, 3.5A Synchronous Step-Down Silent Switcher with 2.5μA Quiescent Current

Tools & Simulations

LTspice 1

LT8640 Demo Circuit - 5V 2MHz µPower Ultralow EMI Step-Down Converter (5.7-42V to 5V @ 5A)

Models for the following parts are available in LTspice:

LT8640
LT8640-1
LT8640A
LT8640S-2
LT8640SA

LTpowerCAD 2

Design tools for the following parts are available in LTpowerCAD:

LT8640
LT8640S
LT8640SA

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.

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.

Evaluation Kits

LT8640EUDC Demo Board | µPower Buck Silent Switcher, 5.7V ≤ VIN ≤ 42V; VOUT= 5V @ 5A

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Product Details

Demonstration circuit 2202A is a 42V, 5A micropower synchronous step-down Silent Switcher^® with spread spectrum frequency modulation featuring the LT8640. The demo board is designed for 5V output from a 5.7V to 42V input. The wide input range allows a variety of input sources, such as automotive batteries and industrial supplies. The LT8640 is a compact, ultralow emission, high efficiency, and high speed synchronous monolithic step-down 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/EMC emissions. Selectable spread spectrum mode can further improve EMI/EMC performance. Ultralow 2.5μA quiescent current in Burst Mode^® operation achieves high efficiency at very light loads. Fast minimum on-time of 40ns enables high V_IN to low V_OUT conversion at high frequency.