IRS2336D International Rectifier Corp., IRS2336D Datasheet - Page 29

• Manufacturer Part Number: IRS2336D
• Description: High Voltage 3 Phase Gate Driver Ic
• Manufacturer: International Rectifier Corp.

A bootstrap MOSFET is suitable for most of the PWM modulation schemes and can be used either in parallel with
the external bootstrap network (i.e., diode and 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. An example of this limitation may
arise when this functionality is used in non-complementary PWM schemes (typically 6-step modulations) and at very
high PWM duty cycle. In these cases, superior performances can be achieved by using an external bootstrap diode
in parallel with the internal bootstrap network.
Bootstrap Power Supply Design
For information related to the design of the bootstrap power supply while using the integrated bootstrap functionality
of the IRS2336xD family, please refer to Application Note 1123 (AN-1123) entitled “Bootstrap Network Analysis:
Focusing on the Integrated Bootstrap Functionality.” This application note is available at www.irf.com.
For information related to the design of a standard bootstrap power supply (i.e., using an external discrete diode)
please refer to Design Tip 04-4 (DT04-4) entitled “Using Monolithic High Voltage Gate Drivers.” This design tip is
available at www.irf.com.
Separate Logic and Power Grounds
The IRS2336xD has separate logic and power ground pin (V
problems that can occur in power conversion applications. Current sensing shunts are commonly used in many
applications for power inverter protection (i.e., over-current protection), and in the case of motor drive applications,
for motor current measurements. In these situations, it is often beneficial to separate the logic and power grounds.
Figure 24 shows a HVIC with separate V
V
ITRIP pin and the V
output voltage used to drive the low-side gate is V
output voltage of the driver minus the drop across R
SS
Figure 22: Internal bootstrap MOSFET connection
www.irf.com
is used as the reference point for the logic and over-current circuitry; V
V
CC
SS
pin. Alternatively, the COM pin is the reference point for the low-side gate drive circuitry. The
SS
and COM pins and how these two grounds are used in the system. The
V
V
V
B1
B2
B3
LO
-COM; the gate-emitter voltage (V
G,LO
.
29
V
th
SS
~ 1.1(V
Bootstrap
MOSFET
V
Figure 23: Bootstrap MOSFET state diagram
CC
state
=15 V
and COM respectively) to eliminate some of the noise
CC
LO
V
)
BS
ON
X
in the figure is the voltage between the
IRS2336xD Family
GE
) of the low-side switch is the
OFF
Bootstrap
MOSFET
disabled
© 2008 International Rectifier
ON
Time