VDDCORE/VCAP setting

[Peet19]

Hi everyone!

I want to use an 18F25J10 PIC, but I don't understand the VDDCORE/VCAP setting. I have read the data sheet a lot, but everything is still not completely clear.VDDCORE is the core of the chip, which can be supplied with a 2.5V voltage separately, but there is a built-in voltage regulator that must be enabled.If I enable it, do I need to put a 10uF capacitor on this pin?If I don't enable 2.5V?I can't find an ENVREG pin anywhere. Where should it be enabled?Am I right at all?Thank you in advance for your help!

 

[Nigel Goodwin]

Page 23 of the datasheet shows the minimum connections, and page 25 clearly says you MUST use a suitable capacitor if you're using the internal regulator (and suggests a suitable component). ENVREG is explained on page 43 - linked to Vdd to enable the internal regulator - on devices which include ENVREG. Page 243 explains what happens if it doesn't have it, with F type devices requiring the special 10uF.

As I see it you just need the 10uF for your F series component.

Any particular reason you're using this chip?, are you looking for a cheap device for large scale production?.

 

[Peet19]

Thanks. There is no ENVREG pin on this. So how do I enable it now? I put a 10uF capacitor on the VDDCORE pin, but I don't know where to enable it. Or is that enough?Yes, it's a pretty cheap PIC and I'm planning a programmable thermostat with an LCD display. I even thought about the 18F24K20 or the K22, but you can't get them very often. I think Microchip stopped production of the K20.Now how do I enable the voltage regulator?

 

[rjenkinsgb]

On the types we use that need a VCAP capacitor, we use a 10uF surface mount ceramic close in to the MCU.

 

[tumbleweed]

On the 18F there is no ENVREG pin, just connect a 10uF to VDDCORE.
There's nothing else you must do. When you apply VDD you should measure 2.5V at the VDDCORE pin.

The 18LF do not have the regulator and you have to supply VDDCORE externally.

 

[Peet19]

I understand, thank you so mutch.

 

[Peet19]

One more quick question.
I don't understand the output current of the ports exactly.
Can PORTA, D, E only give 4mA output current?

 

[tumbleweed]

Can PORTA, D, E only give 4mA output current?

That's the spec on the 25J10. Many of the 'J' family are like this.

 

[Peet19]

Oh, that's not good. Thanks.

 

[tumbleweed]

The Q family is pretty nice and can run at lower VDD without requiring a VDDCORE/VCAP, something like an 18F25Q10, although I know getting parts is still a problem...

 

[Peet19]

I undestand, thanks.