LT8643S/
LT8643SA

RECOMMENDED FOR NEW DESIGNS

42V, 6A Synchronous Step-Down Silent Switcher 2 with 2.5μA Quiescent Current

Data Sheet (Rev. D) Product Selection Table
Part Models
10
1ku List Price
Starting From $5.48
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Part Details

  • Silent Switcher ®2 Architecture
    • Ultralow EMI Emissions on Any PCB
    • Eliminates PCB Layout Sensitivity
    • Internal Bypass Capacitors Reduce Radiated EMI
    • Optional Spread Spectrum Modulation
  • High Efficiency at High Frequency
    • Up to 96% Efficiency at 1MHz, 12VIN to 5VOUT
    • Up to 95% Efficiency at 2MHz, 12VIN to 5VOUT
  • Wide Input Voltage Range: 3.4V to 42V
  • Output Voltage Range: 0.97V to 10V(LT8640S/LT8643S); 0.97V to (VIN – 0.5V) (LT8640SA/LT8643SA)
  • 6A Maximum Continuous, 7A Peak Output
  • Ultralow Quiescent Current Burst Mode® Operation
    • 2.5µA IQ Regulating 12VIN to 3.3VOUT (LT8640S/LT8640SA)
    • Output Ripple < 10mVP-P
  • External Compensation: Fast Transient Response and Current Sharing (LT8643S)
  • Robust High VOUT Operation (LT8640SA/LT8643SA)
    • Safely Tolerates High Reverse Current
  • Fast Minimum Switch On-Time: 30ns
  • Low Dropout Under All Conditions: 100mV at 1A
  • Forced Continuous Mode
  • Adjustable and Synchronizable: 200kHz to 3MHz
  • Output Soft-Start and Tracking
  • Small 24-Lead 4mm × 4mm LQFN Package
  • AEC-Q100 Qualified for Automotive Applications
LT8643S/
LT8643SA
42V, 6A Synchronous Step-Down Silent Switcher 2 with 2.5μA Quiescent Current
LT8640S/LT8643S Application Circuit LT8640S/LT8643S Performance Graph LT8640S/LT8643S Pin Configuration LT8640S/LT8643S Pin Configuration
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Documentation

Data Sheet 1

Reliability Data 1

User Guide 2

Design Note 2

Evaluation Design File 1

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Hardware Ecosystem

Parts Product Life Cycle Description
High Voltage Hot Swap Controllers 1
LTC4380
RECOMMENDED FOR NEW DESIGNS Low Quiescent Current Surge Stopper
Low Voltage Hot Swap Controllers 1
LTC4231
RECOMMENDED FOR NEW DESIGNS Micropower Hot Swap Controller
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Tools & Simulations

LTspice 1

LTpowerCAD 1

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.

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.

Evaluation Kits

eval board
schematic 1
schematic 2
schematic 3
schematic 4
DC2658A

LT8643S Demo Board | VIN = 5.8V to 42V with VOUT = 5V at 6A @ 2MHz

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Product Details

Demonstration circuit 2658A is a 42V, 6A synchronous step-down second generation SILENT SWITCHER with spread spectrum frequency modulation featuring the LT8643S. The demo board is designed for 5V output from a 5.8V to 42V input. The wide input range allows a variety of input sources, such as automotive batteries and industrial supplies. The LT8643S is a compact, ultralow emission, high efficiency, and high speed synchronous monolithic step-down switching regulator. The integrated bypass capacitors optimize all the fast current loops and make it easier to minimize EMI/EMC emissions by reducing layout sensitivity. Selectable spread spectrum mode can further improve EMI/EMC performance. Fast minimum on-time of 30ns enables high VIN to low VOUT conversion at high frequency.

eval board
schematic 5
schematic 6
schematic 7
EVAL-LT8643SA-AZ

LT8643SA| 42V, 6A Synchronous Step-Down Silent Switcher 2

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Product Details

The demonstration circuit EVAL-LT8643SA-AZ is a 42V, 6A micropower synchronous step-down second generation Silent Switcher® with spread spectrum frequency modulation featuring the LT8643SA. The demo board is designed for 5V output from a 5.8V to 42V input. The wide input range allows a variety of input sources, such as automotive batteries and industrial supplies. The LT8643SA is a compact, ultra-low emission, high efficiency, and high speed synchronous monolithic step-down switching regulator. The integrated bypass capacitors optimize all the fast current loops and make it easier to minimize EMI/EMC emissions by reducing layout sensitivity. Selectable spread spectrum mode can further improve EMI/EMC performance. Ultra-low quiescent current in Burst Mode® operation achieves high efficiency at very light loads. Fast minimum on-time of 30ns enables high VIN to low VOUT conversion at high frequency.

Please see user guide for the full description.
DC2658A
LT8643S Demo Board | VIN = 5.8V to 42V with VOUT = 5V at 6A @ 2MHz
DC2658A Evaluation Board DC2658A Evaluation Board - Top View DC2658A Evaluation Board - Bottom View DC2658A
EVAL-LT8643SA-AZ
LT8643SA| 42V, 6A Synchronous Step-Down Silent Switcher 2
EVAL-LT8643SA-AZ Board Photo Angle View EVAL-LT8643SA-AZ Board Photo Top View EVAL-LT8643SA-AZ Board Photo Bottom View

Latest Discussions

51 Weeks Ago
RE: Different results for FRA using LTpowerCAD and LTspice, Specifically LT8643S and LT8390
View related discussion on EngineerZone®

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