replacement for Bidirectional Switch MBS4991 and Triac 2N6346A

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qsa

qsa

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Joined 2007
qsaelectronic.com
#1
Hello have a problem for finished crowbar in NMOS Amplifier,because Devices obsolete,

ONSEMI told me MAC228A4G is replacement for Triac 2N6346A

but for Bidirectional Switch MBS4991 no way, we can offer only SIDACs, it looks like there are no Biderctional Switches offered by our competitors as well. Check with TI as far as I know they might have some stuff to offer

Does somebody have idea for replacement Bidirectional Switch MBS4991 with todays devices ?

regards from Germany
 
#2
qsa said:
Hello have a problem for finished crowbar in NMOS Amplifier,because Devices obsolete,

ONSEMI told me MAC228A4G is replacement for Triac 2N6346A

but for Bidirectional Switch MBS4991 no way, we can offer only SIDACs, it looks like there are no Biderctional Switches offered by our competitors as well. Check with TI as far as I know they might have some stuff to offer

Does somebody have idea for replacement Bidirectional Switch MBS4991 with todays devices ?

regards from Germany
Click to expand...


Look up 4016 and 4066 bi lateral switches.
 
#3
Re: Re: replacement for Bidirectional Switch MBS4991 and Triac 2N6346A

nigelwright7557 said:

Look up 4016 and 4066 bi lateral switches.
Click to expand...


Doubt it very seriously. Those are logic gates, and won't work outside the supply rails.

What's needed is a small triac with a pair of inverse-series zener diodes in the gate. Tie the zener string to MT1 or MT2 to make a 2-terminal device. The zener voltage (plus about 2V) will be the breakover voltage. You'll have to dig up an old data sheet to find out the typical breakover voltage for that particular device.
 
#4
One of my OEMs uses crowbars across the outputs of their power amps. They used to use SAC187 triacs, which are about the same as the 2N6346, but have moved on to more modern types. They used to use the SBS14/MBS4992, but in more recent designs in place of the SBS, they have a pair of SCRs 2N5064 in back to back parallel with their gates connected together. Gates connected to nothing else, just each other.
 
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