leakage losses.

e.g.: HVG steady state consumption is lower than

200

supply 1

pacitor means a voltage drop of 1V.

The internal bootstrap driver gives great advan-

tages: the external fast recovery diode can be

avoided (it usually has great leakage current).

GND (or lower) and in the meanwhile the LVG is

the time in which both conditions are fulfilled and

it has to be long enough to charge the capacitor.

The bootstrap driver introduces a voltage drop

due to

Ohm). At low frequency this drop can be ne-

glected. Anyway

increasing the frequency

it

must be taken in to account.

The following equation is useful to compute the

drop on the bootstrap DMOS:

of the bootstrap capacitor.

For example: using a power MOS with a total

gate charge of 30nC the drop on the bootstrap

µs. In fact:

=

30nC

5

µs

too high, or the circuit topology doesn’t allow a

sufficient charging time, an external diode can be

used.

TO LOAD

D99IN1056

H.V.

HVG

ab

LVG

HVG

LVG

TO LOAD

H.V.

Figure 4. Bootstrap Driver.

-45

-25

0

25

50

75

100

125

0

50

100

150

200

250

Tj (°C)

Typ.

@ Vcc = 15V

Figure 5. Turn On Time vs. Temperature

-45

-25

0

25

50

75

100

125

0

50

100

150

200

250

Tj (°C)

Typ.

@ Vcc = 15V

Figure 6. Turn Off Time vs. Temperature

L6385

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