startup architecture for Bandgap, looking for reference

[Elhafed]

Start up of Bandgap

Hello,

I'm looking for some startup architecture for my Bandgap, can you give me some reference.
Thanks

 

[ashish_chauhan]

Re: Start up of Bandgap

Try using a schimitt trigger to genarate a pulse use that pulase to urn on the mos connected to which ever node u want to inject current into...

You can modify the "on" time of pulse according to ur worst case ...
Once the pulse goes off startup mos is off.

This the basic idea... Ihave implemented in my bgr .... It works fine!

 

[Elhafed]

Re: Start up of Bandgap

Hello,

Many thanks for your answer, but I can't used a Schmitt trigger because my supply power can varied from 5V till 40V.

Regards

 

[harrytrinh]

Re: Start up of Bandgap

You just need to bias for the core of bandgap then using either Vbg compare with a VT or the current which generate by delta Vbe/R compare with an other current to finish start up. Thus either Vbg>VT or delta Vbe>I then you can release start up circuit.
Best

 

[lochiwa]

Re: Start up of Bandgap

It may be more safe and easier to use a follower to pull the BG to make sure it will not stay at the unwanted stable point (VBG=0V). By comparing the VBG with a threshold can sometimes have a problem when e.g. the threshold voltage varies and is larger in some conditions. The startup circuit will pull up the BG voltage all the time.

Even it can work properly, there will be a jump/overshoot at the VBG during startup.

 

[wonbef]

Start up of Bandgap

you can search and get many resources about bandgap references here.

 

[Elhafed]

Re: Start up of Bandgap

Hello,

Many thanks for yours answers.

Regards