Strange voltage regulator question

Projects General Guidance
1

I want to be able to turn the TPS7A7002 regulator on and off using a pin from my Uno using the ENable pin on the regulator. I want the regulator to have a 5 volt input, and a fixed 3.3 volt output. Does this sound possible, and if so, how do I do that?

2

Are you reading the datasheet?

Citing from the document:

EN - Enable input. Pulling this pin to less than 0.5 V turns the regulator off. Connect to VIN if not
being used.

If you read this - what is your question?

3

That is my question. I already know how to use the EN pin. People on the forum keep telling me to include more info in my questions, so that's why I was explaining what I was trying to do.

4

Read the datasheet is that easy.. You got a formula on the first page about two resistors, for setting the output voltage.

5

yes, it possible
From the document:

  • Input Voltage as Low as 1.425 V
    • 380-mV Maximum Dropout at 2 A
    • 600-mV Maximum Dropout at 3 A
    • Adjustable Output from 0.5 V

You should to learn read datasheets yourself if you plan to go further in electronics

6

So R1 should be 110k, and R2 should be 20k? That gives me 3.25 volts. Is that close enough? I have noticed that the 3.3v out of my Uno is sometimes lower than that.

7

Please do not overflow the forum with questions, first learn something...

8

Isn't that the point of the forum? :crazy_face::crazy_face: I wouldn't ask if I knew, obviously.
The point of this forum isn't to inform everyone what I had for breakfast...

9

You can add 2 resistor in series to get closer to 3V3.

10

AND please do not try to answer in any and every thread... First think then write...

11

Ah, yes. I will have to. My calculations suggest that R2 should be 19.6k, so two resistors will have to be used.

12

Table 2 in page 9 of the datasheet contains the examples of resistors values for the most popular cases including 3v3

13

Warning taken and heeded.

14

19.6k

18k + 1.5k = 19.5k
OR
15k + 4.7k = 19.7k

Standard values:

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15

According to the table @b707 kindly pointed out, I will actually need a 30.1k, and a 169 k resistor! But that is also easy to substitute: 30k + 100 ohm = 30.1k and 120k + 47k + 2k = 169k.

16

Both 30.1k and 169k are available in SMD.

17

you can take 30k and 100k + 68k - it give you exactly 3.3v

18

Oh. Well I was trying to follow the datasheet at your suggestion...

19

the exact values don't matter, only the ratio matters

20

Ah, I see.