irs2609d International Rectifier Corp., irs2609d Datasheet - Page 10

• Manufacturer Part Number: irs2609d
• Description: Half-bridge Driver
• Manufacturer: International Rectifier Corp.

Integrated Bootstrap Functionality
The IRS2609D embeds an integrated bootstrap FET that allows an alternative drive of the bootstrap supply for a wide range of
applications.
A bootstrap FET is connected between the floating supply V
The bootstrap FET is suitable for most PWM modulation schemes, including trapezoidal control, and can be used either in
parallel with the external bootstrap network (diode+ resistor) or as a replacement of it. The use of the integrated bootstrap as a
replacement of the external bootstrap network may have some limitations in the following situations:
The summary for the bootstrap state follows:
•
•
diagram for more details.
www.irf.com
•
•
Bootstrap turns-off (immediately) or stays off when at least one of the following conditions are met:
Bootstrap turns-on when:
When the motor runs at a very low current (so that the negative phase voltage decay can be longer than 20us) and
complementary PWM is not used.
At a very high PWM duty cycle due to the bootstrap FET equivalent resistance (R
1- /SD is low
2- /SD is high, IN is low and V
3- /SD is high, IN is high (DT period excluded)
4- /SD is high, IN is high and V
1- /SD in high, IN is low and V
2- /SD in high, IN is high and V
Vcc
Figure 10: Semplified BootFET connection
B
B
B
is high (> 1.1*V
is low (< 1.1(V
is high (> 1.1*V
B
is low (< 1.1(V
BootFet
CC
B
CC
CC
and V
))
)
) (during DT period)
CC
)) (during the DT period). Please refer to the BootFET timing
CC
(see Fig. 10).
Vb
BS
, see page 3).
IRS2609DSPbF
10