18V, 10A Synchronous Step-Down Silent Switcher

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Part Details
Part Models 2
1ku List Price Starting From $3.16
  • Silent Switcher® Architecture
    • Ultralow EMI Emissions
    • Optional Spread Spectrum Modulation
  • High Efficiency at High Frequency
    • Up to 96% Efficiency at 1MHz, 12VIN to 3.3VOUT
    • Up to 95% Efficiency at 2MHz, 12VIN to 3.3VOUT
  • Wide Input Voltage Range: 2.8V to 18V
  • 10A Output Current
  • External Compensation: Fast Transient Response and Current Sharing
  • Low Quiescent Current Burst Mode® Operation
    • 240μA IQ Regulating 12VIN to 1.2VOUT
    • Output Ripple: <10mVP-P
  • Fast Minimum Switch On-Time: 20ns
  • Low Dropout Under All Conditions: 50mV at 1A
  • Forced Continuous Mode
  • Adjustable and Synchronizable: 200kHz to 3MHz
  • Output Soft-Start and Power Good
  • Small 20-Lead 3mm × 4mm LQFN Package
Additional Details
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The LT8642-1 synchronous step-down regulator features Silent Switcher architecture designed to minimize EMI emissions while delivering high efficiency at high switching frequencies. This performance makes the LT8642-1 ideal for noise sensitive applications and environments.

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 20ns minimum on-time allows high step-down ratios even at high switching frequencies. 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 LT8642-1.

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.


  • Server Power Applications
  • Automotive and Industrial Supplies
  • General Purpose Step-Down
LT8642S VIN, BST, INTVCC 4mm × 4mm LQFN
LT8642-1 None 3mm × 4mm LQFN
Part Models 2
1ku List Price Starting From $3.16

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Software & Part Ecosystem

Software & Part Ecosystem

Evaluation Kit

Evaluation Kits 1

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LT8642-1 | 18V, 10A Synchronous Step-Down Silent Switcher



LT8642-1 | 18V, 10A Synchronous Step-Down Silent Switcher

LT8642-1 | 18V, 10A Synchronous Step-Down Silent Switcher

Product Detail

Demonstration circuit 3162A is a 18V, 10A synchronous step-down Silent Switcher® with spread spectrum frequency modulation featuring the LT8642-1. The demo board is designed for 1.2V output from a 2.8V to 18V input. The LT8642-1 is a compact, low emission, high efficiency, and high speed synchronous monolithic stepdown switching regulator. Special Silent Switcher architecture minimizes EMI emissions. Selectable spread spectrum mode can further improve EMI performance. Fast minimum on-time of 20ns enables high VIN to low VOUT conversion at high frequency.

The LT8642-1 switching frequency can be programmed either via a resistor or external clock over a 200kHz to 3MHz range. The default frequency of demo circuit 3162A is 2MHz. The LT8642-1 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 LT8642-1 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 3162A. The LT8642-1 is assembled in a 3mm × 4mm LQFN package with exposed pads 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.

Tools & Simulations

Tools & Simulations 1

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.

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