42V, 15A Synchronous Step-Down DC-DC Regulator

42V, 15A Synchronous Step-Down DC-DC Regulator

The LT8648S synchronous step-down dc-dc regulator from Analog Devices features second generation Silent Switcher architecture designed to minimize EMI emissions while delivering high efficiency at high switching frequencies. This includes the integration of input and boost capacitors to optimize all the fast current loops inside and make it easy to achieve advertised EMI performance by reducing layout sensitivity.

This performance makes the LT8648S suited for noise sensitive applications and environments. It is expected to be used in automotive and industrial systems as well as general-purpose voltage step-down applications.

The fast, clean, low overshoot switching edges enable high efficiency operation even at high switching frequencies, leading to a small overall solution size. Peak current mode control with a 25ns minimum on-time allows high step down ratios even at high switching frequencies.

Simplified schematic

External compensation via the VC pin allows for fast transient response at high switching frequencies. The VC pin also enables current sharing and a CLKOUT pin enables synchronizing other regulators to the LT8648S.

Burst Mode operation enables low standby current consumption, forced continuous mode can control frequency harmonics across the entire output load range, or spread spectrum operation can further reduce EMI emissions. Soft-start and tracking functionality is accessed via the SS pin, and an accurate input voltage UVLO threshold can be set using the EN/UV pin.

Summary of Features:

  • 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 95.5% Efficiency at 1MHz, 12VIN to 5VOUT
    • Up to 93% Efficiency at 2MHz, 12VIN to 5VOUT
  • Wide Input Voltage Range: 3V to 42V
  • 15A Output Current
  • Low Quiescent Current Burst Mode® Operation
    • 100µA IQ Regulating 12VIN to 5VOUT
    • Output Ripple < 10mVP-P
  • External Compensation: Fast Transient Response and Current Sharing
  • Fast Minimum Switch On-Time: 25ns
  • Low Dropout Under All Conditions: 35mV at 1A
  • Forced Continuous Mode
  • Adjustable and Synchronizable: 200kHz to 2.2MHz
  • Output Soft-Start and Power Good
  • Safely Tolerates High Reverse Current
  • Small 36-Lead 7mm × 4mm LQFN Package
  • AEC-Q100 Qualification in Progress
Analog Devices Inc.
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Mike is the founder and editor of Electronics-Lab.com, an electronics engineering community/news and project sharing platform. He studied Electronics and Physics and enjoys everything that has moving electrons and fun. His interests lying on solar cells, microcontrollers and switchmode power supplies. Feel free to reach him for feedback, random tips or just to say hello :-)

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