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well converting 5v to a voltage lower than that is easy using a regulators... you can try one of the regulator circuits like series regulator,shunt regulator etc.....
If you don't need much current, say, less than 15mA (LM358), you can use a 2-resistor voltage divider followed by an opamp voltage follower, 2.5V zener voltage reference etc. etc. ..
For higher currents look for low dropout voltage regulators ..
Here are some examples: **broken link removed**
the answer should be determined by your purpose. if you need only a voltage, you can get it through resistors. if you need voltage and current, you need a regulator.
the answer should be determined by your purpose. if you need only a voltage, you can get it through resistors. if you need voltage and current, you need a regulator.
i agree with him. in my case, i have designed a voltage reference using a bandgap circuit instead of a regulator. it also serve the purpose. i need to lower the voltage and at the same time it have to be temperature invariant.
I think you have to describe your goal, is your 5v voltage stable, and is the 2.5v you needed is independent with power supply, temparature and process?
Simplest way is to use the inverter. i.e. Select 5V NMOS and PMOS devices. Supply voltage for Inverter is 5V. Input swinging from 0 to 2.5V. At the output of Inverter .... u will get low swing ... so, add two more inverters of 2.5V supply for full swing ....
It depends on your requirement.
If you need a low noise converter, LDO is good.
If efficient or heat generate is important, DC/DC is good.
If just need a voltage conversion, just us resistors.
Thangks you all! ic supply is 5v !but ic working voltage is 2.5v ! ic current is 50-100mA,!what i think is choose dc-dc or ldo! if iselect dc-dc !I dont hope to use L or lager C !
I checked a number of LM317's in the usual circuit with two 220 Ω resistors
and they all worked, but only just. If I lowered the supply voltage to 4,5v
most of them lost it completely, and that was without any load. I also checked
a LT1085CT and this one kept working down to 3,6 v, also witout any load.
Take a look at the datasheet:https://www.linear.com/pc/productDetail.do?navId=H0,C1,C1003,C1040,C1055,P1283
I think that you will agree that this regulator is a suitable candidate for your
application. A 3 A regulator is a lot of overkill but it doesn't matter if you hit
a mosquito with a newspaper or with a baseball bat, main thing is that you've
got it ! 8) Replace the 365 Ω trimpot in the schematic with a 121 Ω resistor and you've got the 2,5 v you need.
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