L6393DTR datasheet(15/19 Pages) STMICROELECTRONICS

Part #	L6393DTR

Description	Half-bridge gate driver

PDF	19 Pages

Scroll/Zoom	100%

Manufacturer	STMICROELECTRONICS [STMicroelectronics]

Direct Link	http://www.st.com

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15 / 19 page

L6393

Bootstrap driver

Doc ID 14497 Rev 4

15/19

The following equation is useful to compute the drop on the bootstrap DMOS:

where Qgate is the gate charge of the external power MOS, RDSon is the on resistance of the

bootstrap DMOS, and Tcharge is the charging time of the bootstrap capacitor.

For example: using a power MOS with a total gate charge of 30 nC the drop on the

bootstrap DMOS is about 1 V, if the Tcharge is 5 µs. In fact:

Vdrop has to be taken into account when the voltage drop on CBOOT is calculated: if this drop

is too high, or the circuit topology doesn’t allow a sufficient charging time, an external diode

can be used.

Figure 7.

Bootstrap driver

drop

arg Rdson

drop

gate

arg

-------------------R

dson

→

drop

30nC

μS

--------------- 120

Ω 0.7V

∼

⋅

L6393DTR Datasheet(PDF) 15 Page - STMicroelectronics