HIN

HVG

LVG

LIN

D99IN1053

Figure 1. Input/Output Timing Diagram

For both high and low side buffers @25˚C Tamb

0

1

2

3

4

5

C (nF)

0

50

100

150

200

250

time

(nsec)

Tr

D99IN1054

Tf

Figure 2. Typical Rise and Fall Times vs.

Load Capacitance

0

2468

10

12

14

10

Iq

(

µA)

D99IN1055

Figure 3. Quiescent Current vs. Supply

Voltage

BOOTSTRAP DRIVER

A bootstrap circuitry is needed to supply the high

voltage section. This function is normally accom-

plished by a high voltage fast recovery diode (fig.

4a). In the L6385 a patented integrated structure

replaces the external diode. It is realized by a

high voltage DMOS, driven synchronously with

the low side driver (LVG), with in series a diode,

as shown in fig. 4b

An internal charge pump (fig. 4b) provides the

DMOS driving voltage .

The diode connected in series to the DMOS has

been added to avoid undesirable turn on of it.

CBOOT selection and charging:

MOS can be seen as an equivalent capacitor.

gate charge :

=

is proportional to the cyclical voltage loss .

It has to be:

3nF. With

300mV.

If HVG has to be supplied for a long time, the

L6385

4/9