IRS211(7,71,8)(S)

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© 2008 International Rectifier

11

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

DC bus voltage.

Q1

Q2

D1

D2

DC+ BUS

DC- BUS

Input

Voltage

To

Load

Figure 5: Half Bridge Circuit

Q1

OFF

Q2

OFF

D1

D2

DC+ BUS

DC- BUS

Figure 6: Q1 conducting

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

DC bus voltage to the negative DC bus voltage.

The IRS21171SPBF is not recommended for new designs. For new designs, we recommend IRS2117SPbF or IRS25752LPbF