LT8640/LT8643 Synchronous Step-Down Regulator

Analog Devices’ 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 RegulatorPower by Linear / Analog Devices’ LT8640 and LT8643 synchronous step-down regulators feature 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 LT8640 and LT8643 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 30 ns minimum on-time allows high step-down 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 LT8640 and LT8643.

Features
  • 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

Applications

  • Automotive and industrial supplies
  • General purpose step-down
  • Ultra-low quiescent Current Burst Mode® operation
  • 2.5 μA IQ regulating 12 VIN to 3.3 VOUT
  • Output ripple < 10 mVP-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
Image of Linear Technology's LT8640S Synchronous Step-Down Regulator Typical Application Image of Linear Technology's LT8640S Synchronous Step-Down Regulator Graph

LT8640 Synchronous Step-Down Regulator

ImageManufacturer Part NumberDescriptionAvailable QuantityView Details
LT8640HUDC#PBF datasheet linkIC REG BUCK ADJ 5A 18QFNLT8640HUDC#PBFIC REG BUCK ADJ 5A 18QFN146 - Immediate
LT8640HUDC#PBF product page link
LT8640EUDC-1#TRPBF datasheet linkIC REG BUCK ADJ 5A 18QFNLT8640EUDC-1#TRPBFIC REG BUCK ADJ 5A 18QFN167 - Immediate
LT8640EUDC-1#TRPBF product page link
LT8640HUDC#TRPBF datasheet linkIC REG BUCK ADJ 5A 18QFNLT8640HUDC#TRPBFIC REG BUCK ADJ 5A 18QFN1858 - Immediate
LT8640HUDC#TRPBF product page link
LT8640EUDC#PBF datasheet linkIC REG BUCK ADJ 5A 18QFNLT8640EUDC#PBFIC REG BUCK ADJ 5A 18QFN0LT8640EUDC#PBF product page link
LT8640EUDC-1#PBF datasheet linkIC REG BUCK ADJ 5A 18QFNLT8640EUDC-1#PBFIC REG BUCK ADJ 5A 18QFN0LT8640EUDC-1#PBF product page link
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LT8643 Synchronous Step-Down Regulators

ImageManufacturer Part NumberDescriptionAvailable QuantityView Details
LT8643SEV#PBF datasheet linkIC REG BUCK SYNC 42V 7A SYNC 24LT8643SEV#PBFIC REG BUCK SYNC 42V 7A SYNC 24934 - Immediate
LT8643SEV#PBF product page link
LT8643SIV#PBF datasheet linkIC REG BUCK SYNC 42V 7A 24 LGALT8643SIV#PBFIC REG BUCK SYNC 42V 7A 24 LGA477 - Immediate
LT8643SIV#PBF product page link

Demo Boards

ImageManufacturer Part NumberDescriptionAvailable QuantityView Details
DC2202A datasheet linkDEMO BOARD FOR LT8640DC2202ADEMO BOARD FOR LT86402 - Immediate
DC2202A product page link
DC2530A datasheet linkLT8640S DEMO BOARD VIN = 5.8V TODC2530ALT8640S DEMO BOARD VIN = 5.8V TO0DC2530A product page link
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Published: 2017-04-14