PIC12C672T-10/SM Microchip Technology, PIC12C672T-10/SM Datasheet - Page 390

• Manufacturer Part Number: PIC12C672T-10/SM
• Description: IC MCU OTP 2KX14 A/D 8-SOIJ
• Manufacturer: Microchip Technology
• Series: PIC® 12Cr

Specifications of PIC12C672T-10/SM

• Core Processor: PIC
• Core Size: 8-Bit
• Speed: 10MHz
• 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: 0°C ~ 70°C
• Package / Case: 8-SOIC (5.3mm Width), 8-SOP, 8-SOEIAJ
• For Use With: XLT08SO-1 - SOCKET TRANSITION 8SOIC 150/208AC164312 - MODULE SKT FOR PM3 16SOIC309-1048 - ADAPTER 8-SOIC TO 8-DIP309-1047 - ADAPTER 8-SOIC TO 8-DIP
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Eeprom Size: -
• Connectivity: -

PICmicro MID-RANGE MCU FAMILY
21.4
DS31021A-page 21-6
A/D Acquisition Requirements
For the A/D converter to meet its specified accuracy, the charge holding capacitor ( C
be allowed to fully charge to the input channel voltage level. The analog input model is shown in
Figure
directly affect the time required to charge the capacitor C
ance varies over the device voltage (V
ance for analog sources is 10 k . After the analog input channel is selected (changed) the
acquisition must be done before the conversion can be started.
To calculate the minimum acquisition time,
that 1/2 LSb error is used (512 steps for the A/D). The 1/2 LSb error is the maximum error allowed
for the A/D to meet its specified resolution.
Equation 21-1:
Equation 21-2:
Example 21-1
lation is based on the following system assumptions.
Rs
Conversion Error
V
Temperature
V
Example 21-1:
T
V
or
Tc
T
T
T
T
DD
HOLD
ACQ
ACQ
ACQ
C
ACQ
HOLD
=
21-3. The source impedance ( R
=
=
=
=
=
=
=
Amplifier Settling Time +
Holding Capacitor Charging Time +
Temperature Coefficient
T
T
5 s + Tc + [(Temp - 25 C)(0.05 s/ C)]
-C
-51.2 pF (1 k + 7 k + 10 k ) ln(0.0020)
-51.2 pF (18 k ) ln(0.0020)
-0.921 s (-6.2146)
5.724 s
5 s + 5.724 s + [(50 C - 25 C)(0.05 s/ C)]
10.724 s + 1.25 s
11.974 s
(V
-(51.2 pF)(1 k + R
shows the calculation of the minimum required acquisition time T
AMP
AMP
HOLD
REF
Acquisition Time
A/D Minimum Charging Time
Calculating the Minimum Required Acquisition Time
+ T
+ T
- (V
(R
=
=
=
=
C
C
IC
REF
+ T
+ T
+ R
/512)) • (1 - e
COFF
COFF
10 k
1/2 LSb
5V
50 C (system max.)
0V @ time = 0
SS
+ R
SS
Rss = 7 k
+ R
DD
S
) ln(1/512)
S
)
) and the internal sampling switch ( R
S
(Figure
) ln(1/511)
(-Tc/C
Equation 21-1
HOLD
21-3). The maximum recommended imped-
(R
IC
HOLD
(see graph in
+ R
may be used. This equation assumes
SS
. The sampling switch ( R
+ R
S
))
1997 Microchip Technology Inc.
)
Figure
21-3)
ACQ
SS
) impedance
. This calcu-
HOLD
SS
) imped-
) must