SATA power connector: max power and power on/ooff feature

Hi, everyone!

I’ve looked at BPi schematics to better understand the SATA power connector (J5) capabilities, and a couple of questions arised.

Max power consumption

FB3 limits connects USB 5V to SATA connector 5V. Looks like a 1.5A fuse/limiter. Given the formula P = VI, the max power that can be drawn via J5 connector is 51.5 = 7.5W. Given this HDD power analysis it looks like we have more than enough power for 2.5’’ HDD, even under heavy load. Did I got it right?

Power on/off management

I really LOVE the power button on BPi; with it one can send a soft shutdown of the CPU AND cut the board power, AND start it again (a feature missing on RPi boards, IMHO). Given the schematic, U4 (an AXP209) is the component that manages the power/reset buttons and the actual shutdown of power switches.

SATA power connector J5 is connected directly to USB power connector, so the board shutdown won’t turn off an HDD. Am I right?

If that’s the case, after a shutdown the HDD is powered but not “used”. Any idea about the power consumption of an HDD in this state?



Regarding the power on/off, I’ve just confirmed (simple multimeter measurement) that powering down the board will switch off the board power, but the 5V on J5 SATA power connector are still on. As expected, given the schematic…