AN2123 STMicroelectronics, AN2123 Datasheet - Page 11

• Manufacturer Part Number: AN2123
• Description: TD351 Advanced IGBT Driver Principles of operation and application
• Manufacturer: STMicroelectronics

AN2123
7 Application schematic
The TD351 application design presented hereafter is based on the active Miller clamp concept. With this
function, the high-side driver can be supplied with a bootstrap system instead of using a floating positive/
negative supply. This concept is applicable to low- and medium-power systems, up to about 10 kW. Main
benefit of this is to reduce the global application cost by making the supply system simpler.
shows the half bridge design concept using the TD35x.
It should be highlighted that the active Miller clamp is fully managed by the TD35x and doesn’t require any
special action from the system controller.
Figure 16. TD35x application concept
The TD351 is able to drive 1200 V IGBT modules up to 50 A or 75 A (depending on IGBT technology and
manufacturer). Key parameters to consider are the TD351 peak output current (0.75 A source / 1.0 A
sink) and the IGBT gate resistor.
The values of gate resistors should be chosen starting with the recommended values from the IGBT
manufacturer. Thanks to the active Miller clamp function, the gate resistor can be tuned independently
from the Miller effect, which normally puts some constraints on the gate resistor. The benefit is to optimize
the turn-on and turn-off behavior, especially regarding switching losses and EMI issues.
Table 1
the peak gate current (with a 15 V supply) required for 10 A to 100 A IGBT modules. Approximate
application power is indicated.
24V
shows the recommended gate resistors values from two major IGBT module manufacturers, and
15V
Rb
5
Cb
+
4.7u
15V
Vreg
4k7
4k7
VREF
VREF
IN
IN
TD35x
TD35x
high side
OUT
CLAMP
OUT
CLAMP
VH
VL
VH
VL
Application schematic
Figures 16
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