87C196 Intel Corporation, 87C196 Datasheet - Page 28

• Manufacturer Part Number: 87C196
• Description: CHMOS 16-BIT MICROCONTROLLER
• Manufacturer: Intel Corporation

87C196CA 87C196CB
WAVEFORM SERIAL PORT SHIFT REGISTER MODE
SERIAL PORT WAVEFORM SHIFT REGISTER MODE
A TO D CHARACTERISTICS
The sample and conversion time of the A D convert-
er in the 8-bit or 10-bit modes is programmed by
loading a byte into the AD TIME Special Function
Register This allows optimizing the A D operation
for specific applications The AD TIME register is
functional for all possible values but the accuracy of
the A D converter is only guaranteed for the times
specified in the operating conditions table
The value loaded into AD TIME bits 5 6 7 deter-
mines the sample time SAMP The value loaded
into AD TIME bits 0 1 2 3 and 4 determines the
bit conversion time CONV These bits as well as
the equation for calculating the total conversion
time T are shown in the following table
28
Equation
T
B
n
4n
7
e
e
e
Sample Time
a
n
(SAMP)
programmed register value
1 state times
total conversion time (states)
number of bits conversion (8 or 10)
e
6
1 to 7
T
AD TIME
e
5
(SAMP)
4
a
Bx (CONV)
1FAFH Byte
Bit Conversion Time
3
n
a
n
1 state times
(CONV)
e
2 to 31
2
a
2 5
1
0
The converter is ratiometric so absolute accuracy is
dependent on the accuracy and stability of V
V
resistor ladder and the analog portion of the convert-
er and input port pins There is also an AD TEST
SFR that allows for conversion on ANGND and
V
lute error listed is without doing any adjustments
A D CONVERTER SPECIFICATION
The specifications given assume adherence to the
operating conditions section of this data sheet Test-
ing is performed with V
operating frequency After a conversion is started
the device is placed in IDLE mode until the conver-
sion is complete
REF
REF
must be close to V
as well as adjusting the zero offset The abso-
CC
REF
since it supplies both the
e
5 12V and 20 MHz
272405 –29
REF