PIC12C672T-04I/MF Microchip Technology, PIC12C672T-04I/MF Datasheet - Page 440

• Manufacturer Part Number: PIC12C672T-04I/MF
• Description: IC MCU OTP 2KX14 W/AD 8-DFN
• Manufacturer: Microchip Technology
• Series: PIC® 12Cr

Specifications of PIC12C672T-04I/MF

• Core Processor: PIC
• Core Size: 8-Bit
• Speed: 4MHz
• Peripherals: POR, WDT
• Number Of I /o: 5
• Program Memory Size: 3.5KB (2K x 14)
• Program Memory Type: OTP
• Ram Size: 128 x 8
• Voltage - Supply (vcc/vdd): 3 V ~ 5.5 V
• Data Converters: A/D 4x8b
• Oscillator Type: Internal
• Operating Temperature: -40°C ~ 85°C
• Package / Case: 8-DFN
• For Use With: AC164324 - MODULE SKT FOR MPLAB 8DFN/16QFNXLT08DFN2 - SOCKET TRANSITION ICE 14DIP/8DFNXLT08DFN - SOCKET TRANSITION ICE 8DFNAC164032 - ADAPTER PICSTART PLUS 8DFN/DIPAC124001 - MODULE SKT PROMATEII 8DIP/SOIC
• Lead Free Status / RoHS Status: Request inventory verification / Request inventory verification
• Eeprom Size: -
• Connectivity: -

PICmicro MID-RANGE MCU FAMILY
23.14
DS31023A-page 23-18
Design Tips
Question 1:
Answer 1:
1.
2.
3.
Question 2:
Answer 2:
After the holding capacitor is disconnected from the input channel, typically 100 ns after the GO
bit is set, the input channel may be changed.
Question 3:
Answer 3:
A very good reference for understanding A/D conversions is the “Analog-Digital Conversion
Handbook” third edition, published by Prentice Hall (ISBN 0-13-03-2848-0).
Make sure you are meeting all of the timing specifications. If you are turning the module
off and on, there is a minimum delay you must wait before taking a sample. If you are
changing input channels, there is a minimum delay you must wait for this as well, and
finally there is T
ADCON0 and should be between 1.6 and 6 s. If T
fully converted before the conversion is terminated, and if T
on the sampling capacitor can droop before the conversion is complete. These timing
specifications are provided in the
data sheet for device specific information.
Often the source impedance of the analog signal is high (greater than 1k ohms) so the
current drawn from the source to charge the sample capacitor can affect accuracy. If the
input signal does not change too quickly, try putting a 0.1 F capacitor on the analog input.
This capacitor will charge to the analog voltage being sampled and supply the instanta-
neous current needed to charge the 120 pF internal holding capacitor.
Finally, straight from the data book: “In systems where the device frequency is low, use of
the A/D clock derived from the device oscillator is preferred...this reduces, to a large
extent, the effects of digital switching noise.” and “In systems where the device will enter
SLEEP mode after start of A/D conversion, the RC clock source selection is required.This
method gives the highest accuracy.”
I find that the Analog to Digital Converter result is not always accurate.
What can I do to improve accuracy?
After starting an A/D conversion may I change the input channel (for my
next conversion)?
Do you know of a good reference on A/D’s?
AD
, which is the time selected for each bit conversion. This is selected in
Preliminary
“Electrical Specifications”
AD
is too short, the result may not be
AD
is made too long the voltage
1997 Microchip Technology Inc.
section. See the device