Zener voltage limiter without voltage drop to the load
Jul 09, 2012 47 Replies
B
bhavanireddy
18
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It needs to be 8-18V to meet the spec/requirement. We have a load dump comp= liant TVS clamping the input to 25V. All the other devices in the system a= re with in the 25V limit except the relays. If the relay can sustain 18V I = think it can easily withstand 25V transient.
Thanks
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K
krw
Specs are now calling for 6V and everything has to work "normally" down to that. Hybrid cars change a lot of assumptions.
Cost is a bigger concern. ;-)
Good thing TVS diodes exist. ;-)
B
bloggs.fredbloggs.fred
mpliant TVS clamping the input to 25V. All the other devices in the system= are with in the 25V limit except the relays. If the relay can sustain 18V = I think it can easily withstand 25V transient.
You seem do have an English comprehension problem. The question was:
DOES THE RELAY HAVE TO PICKUP AT 8 VOLT OPERATING VOLTAG= E ?
J
Joerg
If this means pull-in at 8V then obviously your relay with the 9.5V pick-up spec will not work. Either you need to find another relay or provide buck/boost conversion.
Make sure the TVS will be able to absorb the energy. Also, a TVS has a very large tolerance, meaning the rest of the circuitry should at least stand 35V if you have a 25V TVS.
Another thing to consider: Some folks are quite brutal when it comes to goosing a recalcitrant motor on a cold day. Like hanging the starter aid connection in series to the battery. That could make a 25V TVS explode. Personally I would not use 25V TVS in cars.
Regards, Joerg
http://www.analogconsultants.com/
M
mj
mp compliant TVS clamping the input to 25V. All the other devices in the s= ystem are with in the 25V limit except the relays. If the relay can sustain= 18V I think it can easily withstand 25V transient.
AGE ?
8-18V. Pick up from 8V.
B
bloggs.fredbloggs.fred
a load dump compliant TVS clamping the input to 25V. All the other devices= in the system are with in the 25V limit except the relays. If the relay ca= n sustain 18V I think it can easily withstand 25V transient.
VOLTAGE ?
Ditch that relay and get an automotive grade relay. Then no additional elec= tronics is required.
J
Joerg
load dump compliant TVS clamping the input to 25V. All the other devices in the system are with in the 25V limit except the relays. If the relay can sustain 18V I think it can easily withstand 25V transient.
VOLTAGE ?
electronics is required.
Yep, I'll scond that.
And please, guys (Fred and MJ), do not always hit "Reply All" because then it goes out as email in addition. Click "Reply" instead.
Regards, Joerg
http://www.analogconsultants.com/
B
bloggs.fredbloggs.fred
Okay, well you need something like this:
formatting link
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