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13/19

Rev.0.0

Dual-ChannelIsolatedGateDriver

BTD21520x

Figure9.DeadTimeSetting

The falling edge of one input signal activates the the programmed dead time for the other signal. The dead time of the

output signal is selected by IC, either the dead time set by IC itself or for the dead time of input signal itself, and the IC

output chooses the longer one out of the two. If both input signals are high at the same time, both output signals are

immediately set to low. This feature is intended to prevent shoot-through and does not affect the normal operation of

the dead time settings. The following figure illustrates and demonstrates the various dead time logical operations.

Figure9-2 BTD21520M InputandOutputLogicRelationshipWithInputSignals

State1:

IN2 goes low, IN1 goes high. IN2 sets OUT2 low immediately and assigns the programmed dead time to OUT1.

OUT1 is allowed to go high after the programmed dead time.

State 2:

IN2 goes high, IN1 goes low. Now IN1 sets OUT1 low immediately and assigns the programmed dead time to

OUT2.OUT2 is allowed to go high after the programmed dead time.

State3:

IN2 goes low, IN1 is still low.IN2 sets OUT2 low immediately and assigns the programmed dead time for OUT1.

In this case, the input signal’s own dead time is longer than the programmed dead time. Thus, when IN1 goes high, it

immediately sets OUT1 high.

State4:

IN1 goes low, IN2 is still low. IN1 sets OUT1 low immediately and assigns the programmed dead time to OUT2.

IN2’s own dead time is longer than the programmed dead time.Thus, when IN2 goes high, it immediately sets OUT2 high.

State5:

IN1 goes high, while IN1 and OUT1 are still high.To avoid overshoot, IN1 immediately pulls OUT1 low and keeps

OUT1 low. After some time OUT1 goes low and assigns the programmed dead time to OUT1. OUT2 is already low. After

the programmed dead time, OUT1 is allowed to go high.

State6:

IN2 goes high, while IN1 and OUT1 are still high. To avoid overshoot, IN2 immediately pulls OUT1 low and keeps

OUT2 low. After some time OUT1 goes low and assigns the programmed dead time to OUT2. OUT1 is already low.After

the programmed dead time, OUT2 is allowed to go high.

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