rlrosa/uquad — Issue #19: alimentación beagle+imu+shifter+...
Author: rlrosa
Created: 2011-11-04 06:38:29+00:00
State: open

tenemos que alimentar:

1. el/los level-shifters que usamos para la comm. Las tensiones necesarias son:
* 1.8v
* 3.3v
* la tensión que necesite el i2c
1. la IMU
* 5v

por ahora nada más (excepto el GPS pero asumo que come del USB)

en el expansion header de la beagle **1.8v** y **5.5v** (pines 1 y 2 respectivamente)

* de la [datasheet del beagle](https://github.com/rlrosa/uquad/blob/master/datasheets/beagleboard/BBxMSRM_latest.pdf)

> 7.24.3 Power
> The expansion connector provides two power rails. The first is the VIO_1.8V rail which
> is supplied by the TPS65950. This rail is limited in the current it can supply from the
> TPS65950 and what remains from the current consumed by the BeagleBoard and is
> intended to be used to provide a rail for voltage level conversion only. It is not intended
> to power a lot of circuitry on the expansion board. All signals from the BeagleBoard are
> at 1.8V.
> The other rail is the DC_5V. The same restriction exits on this rail as mentioned in the
> USB section. The amount of available power to an expansion board depends on the
> available power from the DC supply or the USB supply from the PC.

Lo que yo entiendo es que hay que mirar al TPS65950 para el rail de 1.8v, y a la beaglejuice para el de 5v.

* de la [hoja de datos del TPS65950](https://github.com/rlrosa/uquad/blob/master/datasheets/beagleboard/tps65950.pdf)
* El rail de 1.8v tira **700mA** (de acá no queremos sacar casi nada, solo para alimentar el shifter, que debería comer a lo estrella pop no bulímica)

* de la [hoja datos de la imu](https://github.com/rlrosa/uquad/blob/master/datasheets/atomic_imu/datasheet_SFE-0012-DS-6DOFAtomic_v3.pdf)
* A 5v consume **24mA**. Asumo que no vamos a tener problema para sacarle 24mA a la beaglejuice.

En fin, yo digo de alimentar tanto la IMU como el/los shifters desde la beagle
q opinan?