I am using diode top of the right side ( VOUT to VCC ) because I don't want to supply VOUT while USB cable is plugged.
I am using diode right bottom side (VUSB to VCC) because I don't want to reverse polarity to my computer.
Here is what I want to do:
I will use Micro USB only for upload code , after that I won't use Micro USB. I will use only 24V adapter for powering. If I plugged the cable for upload code, VCC will power VOUT then VOUT will power R-78E5-1.0. Probably, I will see 4V on R-78E5-1.0's input. I don't want this that's why I want to put DFLS130LQ-7 digikeylink between VOUT and VCC. I place the other diode for protection computer.
In this schematic, it is looks like I connected two diodes in series. Is this schematic okay ? Is there another way for my situation ?
Hi,
Thanks for the diagram.
How much current will be going through PS2 the 24V to 5V regulator?
The two Schottky diodes will do the job, basically an OR gate.
What current are you expecting them to conduct?
Hint: Connecting net points in simple schematics helps a lot too when signal trcing.
Hi, I couldn't measure but too low. Ethernet module 132 mA + 5ma (this one is relay ) + 3 stepper motor signals (I don't know what is their current consumption) but they are working with Micro USB so under 500mA. This one probably :
Thank you for that schematic . I will go with that. I have one more question. This example Micro USB design don't have 6V 0.5A fuse, should I add to V_USB and does adepter need fuse ?
Hi,
If your 5V regulator is going to drop 24V to 5V, thats 19V and pass 160mA then.
Power Dissipated in the regulator = V * I = 19 * 0.16 = 3Watts.
What package are you using, and do you have a heatsink?
Is the input voltage of the regulator okay with 24V input?
I will use this özdisan.com. This is switching regulator. Here is datasheet .It says, Due to the R-78E’s high efficiency of up to 91% at an output voltage of 5V/1A at the output, no heat sink is required. It says 7V-28 V input voltages okay.
The DFLS130LQ-7 has a very low forward drop. However there is not stock in Digikey or Mouser (I didn't look at other sources).
If you can stand the extra voltage drop you might consider the SR14 diode.
I found in my source. 2950 stock . Actually , I need this but I couldn't find stock that's why I moved
DFLS130LQ-7 . I was looking for MBR120VLSFT1G digikey . I couldn't find SR14 diode. I need this diode for 5V 1A . Basically for Micro USB.
. I will go with that. I have one more question. This example Micro USB design don't have 6V 0.5A fuse, should I add to V_USB and does adepter need fuse ?