LT8645/LT8646 Synchronous Step-Down Regulators

Analog Devices' LT8645 and LT8646 are 65 V, 8 A synchronous step-down/buck regulators. These regulators feature Silent Switcher® architecture designed to minimize EMI/EMC emissions while delivering high efficiency at high switching frequencies. This architecture includes the integration of bypass capacitors to optimize all the fast-current loops inside and make it easy to achieve advertised EMI performance by eliminating layout sensitivity. This performance makes the LT8645 and LT8646 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 40 ns minimum on-time allows high step down ratios even at high switching frequencies. The LT8646 has external compensation via the VC pin to enable current sharing and fast transient response at high switching frequencies.

Burst Mode® operation enables ultra-low standby current consumption, pulse-skipping mode allows full switching frequency at lower output loads, or spread spectrum operation can further reduce EMI/EMC emissions. Soft-start and tracking functionality are 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 synchronizing other regulators to the LT8645 and LT8646. The regulators come in a compact 32-lead LQFN package that has an operating temperature range of -40°C to +125°C. The LT8645 and LT8646 are perfect for automotive, industrial, and GSM power supplies.

Features
Silent Switcher® 2 architecture Eliminates PCB layout sensitivity Internal bypass capacitors reduce radiated EMI Optional spread spectrum modulation Ultra-low EMI/EMC emissions on any PCB High efficiency at high frequency Up to 95% efficiency at 1 MHz, 12 VIN to 5 VOUT Up to 94% efficiency at 2 MHz, 12 VIN to 5 VOUT Wide input voltage range: 3.4 V to 65 V Output soft-start and tracking Small 32-lead 6 mm × 4 mm LQFN package		Ultra-low quiescent current Burst Mode® operation Output ripple < 10 mVP-P 2.5 μA IQ regulating 12 VIN to 3.3 VOUT Low dropout under all conditions: 60 mV at 1 A External compensation: fast transient response and current sharing (LT8646S) Peak current mode operation Fast minimum switch on-time: 40 ns Adjustable and synchronizable: 200 kHz to 2.2 MHz
Applications
Automotive power supplies Industrial power supplies		GSM power supplies Step-down/buck