PIC16C74B-20I/L Microchip Technology Inc., PIC16C74B-20I/L Datasheet - Page 82

• Manufacturer Part Number: PIC16C74B-20I/L
• Description: 44 PIN, 7 KB OTP, 192 RAM, 33 I/O
• Manufacturer: Microchip Technology Inc.

Specifications of PIC16C74B-20I/L

• A/d Inputs: 8-Channel, 8-Bit
• Cpu Speed: 5 MIPS
• Eeprom Memory: 0 Bytes
• Input Output: 33
• Interface: I2C/SPI/USART
• Memory Type: OTP
• Number Of Bits: 8
• Package Type: 44-pin PLCC
• Programmable Memory: 7K Bytes
• Ram Size: 192 Bytes
• Speed: 4 MHz
• Timers: 2-8-bit, 1-16-bit
• Voltage, Range: 2.5-5.5 V
• Lead Free Status / Rohs Status: RoHS Compliant part Electrostatic Device

PIC16C63A/65B/73B/74B
12.1
For the A/D converter to meet its specified accuracy,
the charge holding capacitor (C
to fully charge to the input channel voltage level. The
analog input model is shown in Figure 12-2. The
source impedance (R
switch (R
required to charge the capacitor C
switch (R
(V
offset voltage at the analog input (due to pin leakage
current).
FIGURE 12-2:
EQUATION 12-1:
DS30605C-page 82
T
DD
ACQ
), Figure 12-2. The source impedance affects the
A/D Acquisition Requirements
=
=
SS
SS
) impedance varies over the device voltage
) impedance directly affect the time
Amplifier Settling Time +
Hold Capacitor Charging Time +
Temperature Coefficient
T
T
T
T
AMP
AMP
C
COFF
= - (51.2 pF)(1 k + R
Legend:
+ T
= 5 S
= (Temp -25 C)(0.05 S/ C)
VA
C
ANALOG INPUT MODEL
ACQUISITION TIME
S
+ T
) and the internal sampling
Rs
C
V
I leakage
R
SS
C
T
COFF
PIN
IC
HOLD
ANx
C
5 pF
HOLD
PIN
= input capacitance
= threshold voltage
= leakage current at the pin due to
= interconnect resistance
= sampling switch
= sample/hold capacitance (from DAC)
HOLD
various junctions
) must be allowed
SS
. The sampling
+ R
S
) In(1/511)
V
DD
V
V
T
T
= 0.6 V
= 0.6 V
I leakage
± 500 nA
The maximum recommended impedance for ana-
log sources is 10 k . After the analog input channel is
selected (changed), the acquisition time (T
pass before the conversion can be started.
To
Equation 12-1 may be used. This equation assumes
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.
For more information, see the PICmicro™ Mid-Range
MCU Family Reference Manual (DS33023). In general,
however, given a maximum source impedance of
10 k
will be no more than 16 sec.
R
IC
£ 1k
calculate
and a worst case temperature of 100°C, T
V
SS R
DD
Sampling
Switch
6V
5V
4V
3V
2V
SS
the
Sampling Switch
5 6 7 8 9 10 11
V
minimum
SS
C
= DAC capacitance
= 51.2 pF
(k )
HOLD
2000 Microchip Technology Inc.
acquisition
ACQ
) must
time,
ACQ