Dual voltage regulator +5V & -5V

Status
Not open for further replies.
N

NicholasTok

Member level 1
Joined
Oct 2, 2007
Messages
36
Helped
0
Reputation
0
Reaction score
0
Trophy points
1,286
Activity points
1,587
lm7905 input

Hi

I have a small problem with my below schematic because I could not get 5V as I keep getting +2V to -2V.

I am using a +9V battery

If I was to use LM7805 and LM7905 can I use +9V input to get both a + & - 5V output?

I welcome to hear your suggestion

Regard,
Nicholas Tok
 

lm7905 input range

To use LM7905, you need a negative voltage source. A 555 configured as an inverter can provide a low current negative voltage source.
 

lm7905 regulator circuit

asdfgh888 said:
To use LM7905, you need a negative voltage source. A 555 configured as an inverter can provide a low current negative voltage source.
Click to expand...

hi asdfgh888,

after looking into the datesheet of LM7805 and LM7905, in order to generate the + and - 5V my input range is 7V ~ 9V if i was to use a 9V battery. comparing to the circuit i am showing it has an input range from 6V to 9V. unless there is other components which allow a range from 6V ~ 9V

Regards,
Nicholas Tok
 

How much current do you require at +5 and -5v?
 

oddbudman said:
How much current do you require at +5 and -5v?
Click to expand...

hi oddbudman,

around 1mA

regard,
Nicholas Tok

Added after 1 minutes:

i came across this dual voltage regulator circuit using LM317 & LM337, can anyone help me see what is the input range like?
 

if it is just 1 mA, why don't you use two zener witha 7660 IC ?
If you have also a RS232 driver, you will find on it the voltages needed, jus put two regulators around it ( for more info see the data sheet of MAX232 from maxim ).

here the link:

**broken link removed**

You can get + 10 V at pin 2 and -10 V at pin 6; overall you can have directly the + 5 V from the battery with a 7805, and then the - 5 V from a 7905 with the input connected to the 6 pin of MAX 232

Mandi
 

I have understand that dual voltage regulator LM317 & LM337 the Vin range is Vin - Vout = 5V

Which means in order to get a stable 5V output, my min Vin must be Vin - 5V = 5V
Vin = 10V

so the Vin must be equal or more than 10V to have a stable 5V...
 

Status
Not open for further replies.

Similar threads

Menu
Log in
Register
Cookies are required to use this site. You must accept them to continue using the site. Learn more…