LT8640S Synchronous Step-Down Regulator

Linear Technology offers its LT8640S, 42 V, 6 A synchronous step-down Silent Switcher® 2 with a 2.5 µA quiescent current

Image of Linear Technology's LT8640S Synchronous Step-Down RegulatorLinear Technology's LT8640S synchronous step-down regulator features second-generation Silent Switcher architecture, designed to minimize EMI/EMC emissions while delivering high efficiency at high switching frequencies. This includes the integration of bypass capacitors to optimize all the fast current loops inside and make it easier to achieve advertised EMI performance by reducing layout sensitivity. This performance makes the LT8640S 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 30ns minimum on-time allows high stepdown ratios, even at high switching frequencies.

Burst Mode operation enables ultralow standby current consumption, forced continuous mode can control frequency harmonics across the entire output load range, or spread spectrum operation can further reduce EMI/EMC emissions. Soft-start and tracking functionality is accessed via the TR/SS pin, and an accurate input voltage UVLO threshold can be set using the EN/UV pin. A CLKOUT pin enables the synchronized of other regulators to the LT8640S.

  • Silent Switcher 2 architecture
  • Ultralow EMI/EMC 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 1 MHz, 12 VIN to 5 VOUT
  • Up to 95% efficiency at 2 MHz, 12 VIN to 5 VOUT
  • Wide input voltage range: 3.4 V to 42 V
  • 6 A maximum continuous output, 7 A peak output


  • Automotive and industrial supplies
  • General purpose step-down
  • Ultralow quiescent Current Burst Mode® operation
  • 2.5 μA IQ regulating 12 VIN to 3.3 VOUT
  • Output ripple < 10="">P-P
  • Fast minimum switch on-time: 30 ns
  • Low dropout under all conditions: 100 mV at 1 A
  • Forced continuous mode
  • Safely tolerates inductor saturation in overload
  • Adjustable and synchronizable: 200 kHz to 3 MHz
  • Output soft-start and tracking
  • Small, 24-lead, 4 mm x 4 mm LQFN package
Image of Linear Technology's LT8640S Synchronous Step-Down Regulator Typical Application Image of Linear Technology's LT8640S Synchronous Step-Down Regulator Graph

LT8640S Synchronous Step-Down Regulator

ImageManufacturer Part NumberDescriptionAvailable QuantityView Details
LT8640SEV#PBF datasheet linkIC REG BUCK ADJ 6A 42V 24LGALT8640SEV#PBFIC REG BUCK ADJ 6A 42V 24LGA113 - Immediate
LT8640SEV#PBF product page link
LT8640SIV#PBF datasheet linkIC REG BUCK ADJ 6A 42V 24LGALT8640SIV#PBFIC REG BUCK ADJ 6A 42V 24LGA535 - Immediate
LT8640SIV#PBF product page link
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Published: 2017-04-14