Datasheet

Additional features and limitations ST1S14
14/46 DocID17977 Rev 2
5 Additional features and limitations
5.1 Maximum duty cycle
The bootstrap circuitry charges, cycle-by-cycle, the external bootstrap capacitor to generate
a voltage higher than V
IN
necessary to drive the internal N-channel power element.
An internal linear regulator charges the C
BOOT
during the conduction time of the external
freewheeling diode during the switching activity. The internal logic implements a minimum
OFF time of the high side switch (90 nsec typ.) to prevent the bootstrap discharge at high
duty cycle. As a consequence, the ST1S14 can operate at a maximum duty cycle of around
90 % typ.
The ST1S14 embeds the diode V
D1
required for the bootstrap operation.
Figure 7. Bootstrap operation
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