External Hard drive Power Requirement

[palldat]

Hello,
I was wondering how you determine how much power is needed to run a WD Passport SE 750GB hard drive. It gets power from the usb port

 

[Hawkeye22]

USB 2.0 can only put out 5V at 500mA. Anything higher will require a power brick for the drive.

 

[analytic]

Or a cable with 2 USB connectors (1Amp at 5V).

 

[ko888]

Hello,
I was wondering how you determine how much power is needed to run a WD Passport SE 750GB hard drive. It gets power from the usb port

Since it uses a WD Scorpio Blue 750 GB Mobile Hard Drive:

Electrical Specifications
+5 VDC Current Requirements
Read/Write : 500 mA (2.5 Watts)
Idle : 400 mA (2.0 Watts)
Standby : 50 mA (0.25 Watts)
Sleep : 20 mA (0.1 Watts)