Vddcore??

Thread Starter

spinnaker

Joined Oct 29, 2009
7,830
I have a Pic18F47J53. It has a pin called VDDCORE

The PIC18F47J53 family of devices provides an on-chip voltage regulator to supply the correct voltage levels to the core. Parts designated with an “F” part number (such as PIC18F47J53) have the voltage regulator enabled. These parts can run from 2.15V-3.6V on VDD, but should have the VDDCORE pin connected to VSS through alow-ESR capacitor.

It looks like this is a regulator output. Why would I need that? Shouldn't I be supplying a regulated voltage already? Or do I misunderstand.

What is "the core".

It calls for a cap on that pin. Do I need it if I am not using that ourput?
 

ErnieM

Joined Apr 24, 2011
8,377
A relatively lower supply voltage lets things run faster while not running as hot as they might with a higher supply voltage.

The "core" is the middle where all the interesting things happen. It's where the "w" register lives, among other wonderful things. With a split supply the "guts" run on a lower voltage (<2.7V) while the I/O pins run on up to 3.6V.

Put that cap on that pin, you *are* using that output to filter the core voltage.
 

JohnInTX

Joined Jun 26, 2012
4,787
2.4 Voltage Regulator Pins
(VCAP/VDDCORE)
On “F” devices, a low-ESR (< 5Ω) capacitor is required
on the VCAP/VDDCORE pin to stabilize the voltage
regulator output voltage. The VCAP/VDDCORE pin must
not be connected to VDD and must use a capacitor of 10
F connected to ground. The type can be ceramic or
tantalum. A suitable example is the Murata
GRM21BF50J106ZE01 (10 F, 6.3V) or equivalent.
Designers may use Figure 2-3 to evaluate ESR
equivalence of candidate devices.
It is recommended that the trace length not exceed
0.25 inch (6 mm). Refer to Section 31.0 “Electrical
Characteristics” for additional information.
On “LF” devices, the VCAP/VDDCORE pin must be tied to
a voltage supply at the VDDCORE level. Refer to
Section 31.0 “Electrical Characteristics” for
information on VDD and VDDCORE.
Note that the “LF” versions of these devices are
provided with the voltage regulator permanently
disabled; they must always be provided with a supply
voltage on the VDDCORE pin.
Should be everything you need to get it going.
Datasheet
 
Top