Datasheet

SAM4E [DATASHEET]
Atmel-11157D-ATARM-SAM4E16-SAM4E8-Datasheet_12-Jun-14
1440
Table 47-33 is a computation example for the above formula, where V
ADVREF
= 3V:
47.7.4.3 Example of LSB Computation
The LSB is relative to the analog scale V
ADVREF
.
The term LSB expresses the quantization step in volts, also used for one ADC code variation.
 Single-ended (SE) (ex: V
ADVREF
=3.0V)
̶ Gain = 1, LSB = (3.0V / 4096) = 732 µV
̶ Gain = 2, LSB = (1.5V / 4096) = 366 µV
̶ Gain = 4, LSB = (750 mV / 4096) = 183 µV
 Differential (DIFF) (ex: V
ADVREF
=3.0V)
̶ Gain = 0.5, LSB = (6.0V / 4096) = 1465 µV
̶ Gain = 1, LSB = (3.0V / 4096) = 732 µV
̶ Gain = 2, LSB = (1.5V / 4096) = 366 µV
47.7.5 ADC Electrical Characteristics
The gain error depends on the gain value and the OFFx bit. The data are given with and without autocorrection at
27°C. The data include the ADC performances as the PGA and ADC core cannot be separated. The temperature
and voltage dependency are given as separate parameters.
47.7.5.1 Gain and Offset Errors
For:
 a given gain error: E
G
(%)
 a given ideal code (Ci)
 a given offset error: E
O
(LSB)
the actual code (Ca) is calculated using the following formula
Table 47-33. Input Voltage Values in Single-ended Mode, OFFx=0
Ci Gain = 1 Gain = 2 Gain = 4
0000
2047 1.5 0.75 0.375
4095 3 1.5 0.75
Table 47-34. Voltage and Temperature Dependencies
Symbol Parameter Conditions Min Typ Max Unit
T
GK
Gain Temperature dependency -40°C to 105°C — — 5 ppm/°C
V
GK
Gain Supply dependency VDDIN — — 0.025 %/V
T
OK
Offset Temperature dependency -40°C to 105°C — — 5 ppm/°C
V
OK
Offset Supply dependency VDDIN — — 0.025 %/V
Ca 1
E
G
100
---------
+


C
i
2047–()× 2047 E
O
++=