IRS2117 Datasheet, PDF (11/26 Pages) International Rectifier – SINGLE CHANNEL DRIVER

IRS211(7,71,8)(S)
Tolerant to Negative V_S Transients
A common problem in today’s high-power switching converters is the transient response of the switch node’s
voltage as the power switches transition on and off quickly while carrying a large current. A typical half bridge
circuit is shown in Figure 5; here we define the power switches and diodes of the inverter.
If the high-side switch (e.g., Q1 in Figures 6 and 7) switches off, while the current is flowing to a load, a current
commutation occurs from high-side switch (Q1) to the diode (D2) in parallel with the low-side switch of the
inverter. At the same instance, the voltage node V_S swings from the positive DC bus voltage to the negative
DC bus voltage.
DC+ BUS
Input
Voltage
Q1
D1
VS
Q2
To
Load
D2
DC- BUS
Figure 5: Half Bridge Circuit
DC+ BUS
Q1
D1
OFF
VS
IL
Q2
D2
OFF
Figure 6: Q1 conducting
DC- BUS
Figure 7: D2 conducting
Also when the current flows from the load back to the inverter (see Figures 8 and 9), and Q2 switches on, the
current commutation occurs from D1 to Q2. At the same instance, the voltage node V_S swings from the positive
DC bus voltage to the negative DC bus voltage.
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