7.4V LiPo power source for BS2?
wperko
Posts: 66
Hi,
What is the best way to connect a 7.4V LiPo battery to a BS2 chip?
Is it safe to directly connect to the Vin pin 24 on the BS2 chip?
OR
Do I have to regulate it with a seperate 5V regulator like on the BOE and HomeWork boards?
If I'm using a 7.4V LiPo and a 5V regulator do I connect the output of the regulator to the Vdd pin 21 AND the 7.4V to the Vin pin 24?
What is the best way to connect a 7.4V LiPo battery to a BS2 chip?
Is it safe to directly connect to the Vin pin 24 on the BS2 chip?
OR
Do I have to regulate it with a seperate 5V regulator like on the BOE and HomeWork boards?
If I'm using a 7.4V LiPo and a 5V regulator do I connect the output of the regulator to the Vdd pin 21 AND the 7.4V to the Vin pin 24?
Comments
If you're using a 7.4V LiPo battery and an external 5V regulator, you can either connect the output of the regulator to Vdd or you can connect the LiPo battery to Vin. By using the built-in regulator, you get a little more isolation between the Stamp's circuitry and the circuitry powered by the external 5V regulator ... useful if you're powering servo motors or other noisy circuitry off the external 5V regulated supply.
thanks ... looking this up online I found all sorts of B.S. about batteries killing BS2 chips ... but it didn't make a lot of sense. This makes my BallBot1 robot and FloppyBots FaceBoard cheaper for end users.
http://www.brainless.org/Robots.html
So, is running the BS2 from the 5V regulator on Vdd pin a better solution?
It depends on what you have connected to the Stamp's I/O pins and how much current is drawn. The regulator is limited to supply about 50mA at most with about 10mA used internally in the Stamp circuitry. The regulator may be limited further by operating temperature if too much power has to be dissipated. Any I/O pin loads to ground (where the I/O pin supplies a high signal) contribute to the current drawn by the Stamp. All you need are a couple of LEDs to exceed the 40mA limit. There are also limits on I/O pin current individually, in groups of 8 (0-7 and 8-15), and total for all I/O pins.
If you're running the BS2 off 7V or higher, you have to keep in mind the current drawn and the heat issue particularly. The higher the voltage (and I/O pin current), the more likely you'll need to run the BS2 from an external regulator supplying 5V.