Schematic or name of power-up circuit

[oyvdahl]

Power-up circuit

Hi
I have a chip that I want to power up by a "wireless electrical transmission" (WET).
My WET can supply 3.3V up to 110 mA.
The chip that needs to be powered has a power consumption of about 70 mA. So no problem there.
But when the chip powers up it needs about 500 mA for about 10ms. Because my WET cannot supply that much, the chip never gets started properly.

So what I need is some kind of capacitor-circuit that charges a capacitor large enough to supply 3.3V and 500mA for 10 ms.
I could either solder together a small circuit myself, but I rather by an IC for it if such a thing exists.

So, my question is: Does anyone know how to do this? Does this type of circuit have a name?


Oyvind
Norway

 

[karesz]

Hi,
Yes so a circuit/component does exist, called "Super Capacitor, or GoldCap"...
One vendor has these soriment: 1mF bis 1F, Low ESR from10 mOhm to 1 Ohm, 2.1V to 12V, measures 12x12mm to 48x30mm.
A Similar Eda topic: 2AA Batteries and one supercap cell.

Some description: New Approaches to Managing High-Current Transient Loads in Battery-Powered Handheld Devices
https://i.cmpnet.com/powermanagementdesignline/2009/11/C0477edited.mht
Tay Yudens "Energy Cap" or Cylinder type Lithium Ion Capacitor:https://www.yuden.co.jp/ut/product/pdf_html/pdf62.html
I would say, your circuits name is = "Super Cap (Pwr Up)Booster"-or "SC PUB" (Skol)
K

 

[oyvdahl]

Thank you! I did not know about the super capacitor.
As I understand it, the supercap is a capacitor with lots of farad's inside. So I still need something around it right? My analog design skills are a little outdated. But do you think a resistor in series with a supercap in parallel on the chip supply do the job?

 

[karesz]

Hi,

What you basically need is some loading/separation circuit, similar as by back up batteries.
I will see for that on my home PC today evening_in par hours_ for you...
K.

 

[karesz]

Hi,
Here some articles, https://www.cap-xx.com/ , appl notes & Design-Aid Calculators for you...
**broken link removed**
Pump up the volume! Supercapacitors enhance audio quality and power in mobile phones:
www.cap-xx.com/news/PumpUpTheVolume
Reasons Choose Ultracaps,: www.ioxus.com
Good progress!
K.

 

[dick_freebird]

You might check whether the high power-up current can be
reduced by some pin condition (like holding down reset
until higher voltage is reached, etc.). Defeating the current
is better than brute force.

 

[oyvdahl]

Thanks for the links karesz!
And thanks for the tip dick_freebird! I will definitely check if holding reset for a few millisecs will do the trick.

 

[karesz]

Also, dick_freebird`s tips are surly right for your start, after than if you have some rest of your start current hungry, you should/can try pls for DN450, (Supercapacitors Can Replace a Backup Battery for Power Ride-Through Applications)Linear Techn. I think these design note is usable for you.
http://cds.linear.com/docs/Design Note/dn450f.pdf
LTC3225 - 150mA Supercapacitor Charger: http://www.linear.com/pc/productDetail.jsp?navId=H0,C1,C1003,C1801,P84365
Replace Batteries in Power Ride-Through Applications with Robust Supercaps and 3mm × 3mm Capacitor Charger:
http://cds.linear.com/docs/LT Magazine/LTMag-V18N03-01-LTC3225-JimDrew.pdf
K.

 

[karesz]

Hi,
I see yet on eBay :
https://stores.ebay.co.uk/IT-Tronic...319QQ_sidZ70350029QQ_trksidZp4634Q2ec0Q2em322
K.