XC161 Derivatives
Peripheral Units (Vol. 2 of 2)
The Analog/Digital Converter
User’s Manual
16-20
V2.2, 2004-01
ADC_X1, V2.1
Total Conversion Time Examples
The time for a complete conversion includes the sample time
t
S
, the conversion itself
(successive approximation and calibration), and the time required to transfer the digital
value to the result register as shown in the example below (standard conversion timing).
The timings refer to module clock cycles, where
t
ADC
= 1/
f
ADC
.
•
Assumptions:
f
ADC
= 40 MHz (i.e.
t
ADC
= 25 ns), ADCTC = 01
B
, ADSTC = 00
B
•
Basic clock:
f
BC
=
f
ADC
/2 = 20 MHz, i.e.
t
BC
= 50 ns
•
Sample time:
t
S
=
t
BC
×
8 = 400 ns
Conversion 10-bit:
•
With post-calibr.:
t
C10P
=
t
S
+ 52
×
t
BC
+ 6
×
t
ADC
= (2600 + 400 + 150) ns = 3.15
µ
s
•
Post-calibr. off:
t
C10
=
t
S
+ 40
×
t
BC
+ 6
×
t
ADC
= (2000 + 400 + 150) ns = 2.55
µ
s
Conversion 8-bit:
•
With post-calibr.:
t
C8P
=
t
S
+ 44
×
t
BC
+ 6
×
t
ADC
= (2200 + 400 + 150) ns = 2.75
µ
s
•
Post-calibr. off:
t
C8
=
t
S
+ 32
×
t
BC
+ 6
×
t
ADC
= (1600 + 400 + 150) ns = 2.15
µ
s
Note: For the exact specification please refer to the data sheet of the selected derivative.
