irs2609d International Rectifier Corp., irs2609d Datasheet - Page 13

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

IRS2609DSPbF
However, in a real inverter circuit, the V
voltage swing does not stop at the level of the negative DC bus, rather it swings below the
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level of the negative DC bus. This undershoot voltage is called “negative V
transient”.
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The circuit shown in Figure 17 depicts one leg of the three phase inverter; Figures 18 and 19 show a simplified illustration of the
commutation of the current between Q1 and D2. The parasitic inductances in the power circuit from the die bonding to the PCB tracks
are lumped together in L
and L
for each IGBT. When the high-side switch is on, V
is below the DC+ voltage by the voltage drops
C
E
S1
associated with the power switch and the parasitic elements of the circuit. When the high-side power switch turns off, the load current
momentarily flows in the low-side freewheeling diode due to the inductive load connected to V
(the load is not shown in these
S1
figures). This current flows from the DC- bus (which is connected to the COM pin of the HVIC) to the load and a negative voltage
between V
and the DC- Bus is induced (i.e., the COM pin of the HVIC is at a higher potential than the V
pin).
S1
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Figure 17: Parasitic Elements
Figure 18: V
positive
Figure 19: V
negative
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In a typical motor drive system, dV/dt is typically designed to be in the range of 3-5 V/ns. The negative V
transient voltage can
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exceed this range during some events such as short circuit and over-current shutdown, when di/dt is greater than in normal operation.
International Rectifier’s HVICs have been designed for the robustness required in many of today’s demanding applications. An
indication of the IRS2609D’s robustness can be seen in Figure 20, where there is represented the IRS2609D Safe Operating Area at
V
=15V based on repetitive negative V
spikes. A negative V
transient voltage falling in the grey area (outside SOA) may lead to IC
BS
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permanent damage; viceversa unwanted functional anomalies or permanent damage to the IC do not appear if negative Vs transients
fall inside SOA.
At V
=15V in case of -V
transients greater than -16.5 V for a period of time greater than 50 ns; the HVIC will hold by design the
BS
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high-side outputs in the off state for 4.5 μs.
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