# I can't understand about voltage regulator and reference....

Discussion in 'Power Electronics' started by Junho Kim, Jul 18, 2016.

1. ### Junho Kim Thread Starter New Member

Jul 18, 2016
2
0
Hi! I'm a student and studying designing circuit.
I can't not understand about regulator and reference.... what is difference between them?
I think there are two kinds of Voltage regulator, linear and switching regulator.
Linear regulator includes shunt and series.
I wonder when i have to use shunt(ex TL431) or series regulator(ex LM7805) and their pros and cons.
When can i use regulator or reference? I'm so confusing....
I'm sorry about my poor English but I believe you can understand what I mean!

2. ### Papabravo Expert

Feb 24, 2006
11,761
2,487
A reference is just a stable fixed value. It is primarily used in circuits where a comparison between two voltages is required. A reference cannot supply large amounts of current. A few milliamps would be about the maximum output current.

A regulator incorporates a reference to determine which way the voltage output must be adjusted to maintain a constant output voltage when the load changes. Regulators supply 100's of milliamps to tens of Amperes of output current.

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3. ### Junho Kim Thread Starter New Member

Jul 18, 2016
2
0
I'm making a charger circuit for smartphone. I used TL431. Is it a regulator or reference?
I think charger circuit needs to limit current. Then do i have to use reference not regulator like 7805?
If i need large current, i have to use regulator. Is it right?

I looked at TL431 datasheet but i couldn't find how to operate it.....

Last edited: Jul 19, 2016
4. ### blocco a spirale AAC Fanatic!

Jun 18, 2008
1,535
411
Didn't you see all the "System Examples" in the datasheet?

5. ### BobTPH Senior Member

Jun 5, 2013
1,217
243
If you are talking about making a USB plug type charger that cell phones universally use now, you do not control the current. You supply a constant 5V. The circuitry to control the current while charging the battery is inside the phone. If you leave the D+ and D- pins alone, you phone will draw a max of 500mA and you must be able to supply that.

Bob