Voltage Questions

jugglesavant

I can't seem to find this information anywhere...· I know it must be available somewhere, but I can't manage to find it.·

1.· What is the max current that I can take from the Vdd on the BS Super Carrier Board?· I would like to run the BS2sx as well as a servo motor.· Is this possible?

2.· What is the maximum Vin for the BS2sx?· Does it have to be under 12V?

Thank you!!
·

Mike Green

1) The maximum current available on a BS2 Super Carrier Board is set by the regulator, an LM2940 which is rated at around 1A. There is no heat sink on the regulator and the dissipation is determined by the Vin to Vdd voltage drop. Consult the LM2940 datasheet for information on heatsinking and power dissipation.

2) The maximum Vin for the BS2sx is set by the regulator on the substrate, an LT1121 which has a maximum input voltage of 30V. Again, the power dissipation may limit how much current you can draw. Not only the processor, but the I/O source current has to come from this regulator. If you have a lot of LEDs or a reed relay or two, this may limit the possible Vin.

jugglesavant

It looks to me though that the Vin, before regulation is put into the board on pin 24. Is this incorrect?

Mike Green

Vin is pin 24 of the BS2sx. There are complete schematics available through links on the product pages for the Stamps and the development boards other than the BOE USB.

Chris Savage

Hello,

·· The max V_IN for the BS2sx Module is 12V before the regulator will shut down. Now, on the Super Carrier Board the BASIC Stamp Module will get its power from V_DD, not V_IN as on other boards, so input voltage will be determined by the LM2940 and total current draw (more accurately, power dissipation). Take care.

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Chris Savage
Parallax Tech Support