I need negative voltage in my circuit with common ground wrt positive voltage

1. One option is to generate negative supply by placing a full- bridhe & then using 7905.
It includes lots of extra components to be used.
2. Another option is to use TC7660. Simple to use & works good. Only problem is its output voltage falls with current. For a load current of -10 mA and a supply voltage of +5V, the output voltage would be -4.3V.

3.I need to generate regulated -5V,-2.5V&-1.8V

4.Any other way to do that?

 

You could use a SMPS with an isolated output. Its more-positive output terminal would connect to the common ground.

 

How much current do you need for each output?

 

I need negative voltage in my circuit with common ground wrt positive voltage

1. One option is to generate negative supply by placing a full- bridhe & then using 7905.
It includes lots of extra components to be used.
2. Another option is to use TC7660. Simple to use & works good. Only problem is its output voltage falls with current. For a load current of -10 mA and a supply voltage of +5V, the output voltage would be -4.3V.

3.I need to generate regulated -5V,-2.5V&-1.8V

4.Any other way to do that?

There are plenty of negative rail inverter circuits online, and nearly as many off the shelf chips that do the job - or it can be as ready to hand as a 555 with a charge-pump on the output.

 

A buck-boost converter will produce a negative voltage.

Bob

 

A buck-boost converter will produce a negative voltage.

Bob

An inverter that outputs the opposite polarity to the input doesn't have to be buck-boost topology to span output voltage both above and below the input voltage.