Datasheet

20 24= + ´ W

d dt

t ns R ns / k

UCC25600

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SLUS846B –SEPTEMBER 2008– REVISED JULY 2011

Adjustable Dead Time

Resonant half-bridge converter relies on the resonant tank current at MOSFETs turn-off to achieve soft switching

and reduce switching loss. Higher turn-off current provides more energy to discharge the junction capacitor, while

it generates more turn-off loss. Smaller turn-off current reduces turn-off loss, but it requires longer time to

discharge MOSFETs junction capacitors and achieve soft switching. By choosing an appropriate dead time,

turn-off current is minimized while still maintaining zero-voltage switching, and best system performance is

realized.

In UCC25600, dead time can be adjusted through a single resistor from DT pin to ground. With internal 2.25-V

voltage reference, the current flow through the resistor sets the dead time.

(9)

To prevent shoot through when DT pin accidentally connects to ground, a minimum 120-ns dead time is inserted

into the two gate driver outputs. Any dead-time setting less than 120-ns, will be limited to 120-ns.