# How can I power a device that requires 5-7V and 2.5-6 mA with what I have?

I have voltage pins on one device that outputs 6.23V DC and 70 mA DC. What type of circuit do I have to build that can power up another device that requires 5-7V DC and 2.5-6 mA DC using my 6.23 V source?

EDIT The source outputs about 60-80 mA current, not 0.1 mA

• Not enough details. The 6.23V already fulfills the 5-7V DC range. What is the rated output current from the device that outputs the 6.23V? – lemonlime Jul 17 '18 at 19:19
• the second device requires a voltage that is higher than 5V and less than 7V ..... is 6.23V higher than 5V? .... is it less than 7V? ................... can the first device provide 6mA of current? – jsotola Jul 17 '18 at 19:22
• the 6.23V device supplies 0.1 mA of current. @jsotola, i thought that was obvious but I wanted to add it just in case it turned out to be important in some way. I suck at designing analog circuits. – mobin.ctr Jul 17 '18 at 19:23
• What if the input drops to 5V? do you still want 6V out with more output power than input? So what is the input max range vs output? – Sunnyskyguy EE75 Jul 17 '18 at 19:34
• better to ask then to be sorry ...... one other thing to check: do the two devices have the same ground? – jsotola Jul 17 '18 at 19:36

If your first device (the "supply") can only provide 0.1mA then you will need an external supply.

5V@6mA = 30mW

6.23V@0.1mA = 0.623mW

30mW > 0.623mW

Energy is conserved.

Edit: You have added that the power source is intended to operate a cooling fan. In that case, it seems much more likely to be 100mA (0.1A) than 0.1mA. There is still potentially an issue with the ground and also the possibility it may be PWM'd or something like that (since the voltage is non-standard for a fan).

An external 5V supply really seems to me like the safest way to go unless you really need to avoid that.

• No it isn't . It's radiated +1 for sarcasm -1 for misunderstanding . no comment – Sunnyskyguy EE75 Jul 17 '18 at 20:26