Mar 18, 2020
03:24 AM
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Mar 18, 2020
03:24 AM
1 Solution
Mar 20, 2020
04:14 PM
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Mar 20, 2020
04:14 PM
Hi TechGirl,
as described in [1, p.4],
other than with a MOSFET, an IGBT does not inherently contain a freewheeling, or body, diode by design. This diode, however, is a part needed to protect the switch providing a freewheeling path to prevent reverse current. When choosing a component, care has to be taken to either add a suitable diode or go for a component with an integrated diode die.
This means that a classic IGBT cannot conduct a reverse current. The reason is the p-doped (red) layer on the collector (C) side which forms a PN junction with the N-doped (green) drift region: in reverse direction, this PN junction is in blocking mode. Thus, free-wheeling diodes need to be put additionally, either as separate chips next to the IGBT or integrated on the IGBT chip. The latter variant is referred to as reverse conducting (RC) IGBT: areas of the chip which are intended to work as diode have to be n-doped (green) on the collector side.
Hope this helps!
Best regards,
Klaus
[1] IGBT-basic know-how
as described in [1, p.4],
other than with a MOSFET, an IGBT does not inherently contain a freewheeling, or body, diode by design. This diode, however, is a part needed to protect the switch providing a freewheeling path to prevent reverse current. When choosing a component, care has to be taken to either add a suitable diode or go for a component with an integrated diode die.
This means that a classic IGBT cannot conduct a reverse current. The reason is the p-doped (red) layer on the collector (C) side which forms a PN junction with the N-doped (green) drift region: in reverse direction, this PN junction is in blocking mode. Thus, free-wheeling diodes need to be put additionally, either as separate chips next to the IGBT or integrated on the IGBT chip. The latter variant is referred to as reverse conducting (RC) IGBT: areas of the chip which are intended to work as diode have to be n-doped (green) on the collector side.
Hope this helps!
Best regards,
Klaus
[1] IGBT-basic know-how
1 Reply
Mar 20, 2020
04:14 PM
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Mar 20, 2020
04:14 PM
Hi TechGirl,
as described in [1, p.4],
other than with a MOSFET, an IGBT does not inherently contain a freewheeling, or body, diode by design. This diode, however, is a part needed to protect the switch providing a freewheeling path to prevent reverse current. When choosing a component, care has to be taken to either add a suitable diode or go for a component with an integrated diode die.
This means that a classic IGBT cannot conduct a reverse current. The reason is the p-doped (red) layer on the collector (C) side which forms a PN junction with the N-doped (green) drift region: in reverse direction, this PN junction is in blocking mode. Thus, free-wheeling diodes need to be put additionally, either as separate chips next to the IGBT or integrated on the IGBT chip. The latter variant is referred to as reverse conducting (RC) IGBT: areas of the chip which are intended to work as diode have to be n-doped (green) on the collector side.
Hope this helps!
Best regards,
Klaus
[1] IGBT-basic know-how
as described in [1, p.4],
other than with a MOSFET, an IGBT does not inherently contain a freewheeling, or body, diode by design. This diode, however, is a part needed to protect the switch providing a freewheeling path to prevent reverse current. When choosing a component, care has to be taken to either add a suitable diode or go for a component with an integrated diode die.
This means that a classic IGBT cannot conduct a reverse current. The reason is the p-doped (red) layer on the collector (C) side which forms a PN junction with the N-doped (green) drift region: in reverse direction, this PN junction is in blocking mode. Thus, free-wheeling diodes need to be put additionally, either as separate chips next to the IGBT or integrated on the IGBT chip. The latter variant is referred to as reverse conducting (RC) IGBT: areas of the chip which are intended to work as diode have to be n-doped (green) on the collector side.
Hope this helps!
Best regards,
Klaus
[1] IGBT-basic know-how