Analog Devices has introduced 8.5A and 2A versions of the 4A LT8650S dual-channel quiet synchronous step-down dc-dc converter.

“The proprietary ‘silent switcher 2’ architecture along with spread spectrum frequency modulation ensures PCB layout robustness to achieve low EMI performance that meet CISPR25 emissions,” according to ADI, which is aiming the products at power supplies for automotive, communications and solid-state drive applications.

The parts are

• LT8652S 8.5A/channel, or 1 channel at 12A, 4 x 7mm LQFN

      Two LT8652Ss can be synchronised to create a four phase 34A supply.

• 2A LT8653S 2A/channel 4 x 3mm LQFN

The ‘S’ suffix in the part numbers refers to the second generation silent switcher technology – claimed to allow fast switching edges for high efficiency at the same time as good EMI/EMC performance. Some of this comes from five ceramic capacitors integrated into the package to cut the length of power supply decoupling loops.

Operation of the higher power 52S is across 300kHz to 3MHz (resistor-programmable, 20ns minimum switch ‘on’ time), and 93.6% efficiency is available with a 6A 3.3V output from 12Vin at 1MHz, or 85.6% with a 1V output.

Topology is constant-frequency peak-current, with the clock starting  each cycle and current in the inductor increasing until it trips a comparator which turns off the top power switch.

LT8652S-DC2523-eval-boardEval boards are available

During light loads, the inductor current is allowed to go negative to maintain the programmed switching frequency (minimum current limits for both power switches prevent high negative current flowing back to the input).

Burst-mode is available at lighter loads.

Because of the high current in the chips, an additional pin is provided for external Kelvin sensing of the load ground – remote output ground deviations up to ±300mV are permitted.