Datasheet

1445
SAM4E [DATASHEET]
Atmel-11157D-ATARM-SAM4E16-SAM4E8-Datasheet_12-Jun-14
Note: 1. N/A: Not applicable
Track and Hold Time versus Source Output Impedance
Figure 47-18 shows a simplified acquisition path.
Figure 47-18. Simplified Acquisition Path
During the tracking phase, the ADC needs to track the input signal during the tracking time shown below:
t
TRACK
= 0.054 x Z
SOURCE
+ 205
with t
TRACK
expressed in ns and Z
SOURCE
expressed in Ω.
The ADC already includes a tracking time of 15 t
CP_ADC
Two cases must be considered:
1. If the calculated tracking time (t
TRACK
) is lower than 15 t
CP_ADC
, then TRACTIM can be set to 0 .
If the calculated tracking time (t
TRACK
) is higher than 15 t
CP_ADC
, then TRACTIM must be set to the correct value.
47.7.5.4 AFE DAC Offset Compensation
1 2 pF 4 pF
2 2 pF 8 pF
44 pFN/A
Table 47-44. Z
IN
Input Impedance
f
S
(MHz) 1 0.5 0.25 0.125 0.0625 0.03125 0.015625 0.007813
C
IN
= 2 pF
Z
IN
(MΩ) 0.51248163264
C
IN
= 4 pF
Z
IN
(MΩ) 0.250.512481632
C
IN
= 8 pF
Z
IN
(MΩ) 0.125 0.25 0.5 1 2 4 8 16
Table 47-43. Input Capacitance (C
IN
) Values
Sample & Hold
12-bit ADC Core
C
IN
MUX
R
ON
Z
SOURCE
Table 47-45. AFE DAC Offset Compensation
Parameter Conditions Min Typ Max Units
Resolution - N — — 12 — bits