180W synchronous DC-DC converter with 95% efficiency at 2MHz

July 05, 2018 // By Nick Flaherty
Analog Devices has launched a 10A, 18V input synchronous step-down switching regulator with efficiency of 95% at a switching frequency of 2MHz.

The LT8642S has a 2.8V to 18V input voltage range for automotive and industrial applications and provides up to 10A of continuous output current to voltages as low as 0.60V.

The Silent Switcher 2 architecture uses two internal input capacitors as well as internal BST and INTVCC capacitors to minimize the area of the hot loops. This reduces EMI emissions as a result of its controlled switching edges and its internal construction using copper pillars in lieu of bond wires and an integral ground plane. The improved EMI performance is not sensitive to PCB layout, simplifying design and reducing risk even when using two-layer PC boards and means the LT8642S easily passes the automotive CISPR 25, Class 5 peak EMI limits with a 2MHz switching frequency over its entire load range. Spread spectrum frequency modulation is available to lower EMI levels further.

Burst Mode operation allows 240µA of quiescent current and an external compensation pin enables fast transient response and current sharing for paralleling multiple devices. A fast minimum on-time of only 25ns enables 2MHz constant frequency switching from a 12V input to a 0.6V output.

The devices uses internal top and bottom high efficiency power switches with the necessary boost diode, oscillator, control and logic circuitry integrated into a single die. Low ripple Burst Mode operation maintains high efficiency at low output currents while keeping output ripple below 10mV P-P and for applications requiring the lowest noise operation, the LT8642S can be programmed to run in forced continuous mode over the entire load range. Its switching frequency is programmable and synchronizable from 200kHz to 3MHz. Special design techniques and a new high speed process enable high efficiency over a wide input voltage range, and the LT8642S current mode topology enables fast transient response and excellent loop stability. Other features include a power good flag, output soft-start/tracking and thermal protection.

The 24-lead 4mm x 4mm LQFN package and high switching frequency keeps external inductors


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