Datasheet

Data Sheet ADuC845/ADuC847/ADuC848
Rev. C | Page 5 of 108
Parameter Min Typ Max Unit Conditions
Normal Mode Rejection 50 Hz/60 Hz
2
On AIN 75 dB
50 Hz/60 Hz ± 1 Hz, 16.6 Hz Fadc, SF = 52H,
chop on, REJ60 on
100 dB 50 Hz ± 1 Hz, 16.6 Hz Fadc, SF = 52H, chop on
67 dB
50 Hz/60 Hz ± 1 Hz, 50 Hz Fadc, SF = 52H,
chop off, REJ60 on
100 dB 50 Hz ± 1 Hz, 50 Hz Fadc, SF = 52H, chop off
Analog Input Current
2
±1 nA T
MAX
= 85°C, buffer on
±5 nA T
MAX
= 125°C, buffer on
Analog Input Current Drift ±5 pA/°C T
MAX
= 85°C, buffer on
±15
pA/°C
T
MAX
= 125°C, buffer on
Average Input Current ±125 nA/V ±2.56 V range, buffer bypassed
Average Input Current Drift ±2 pA/V/°C Buffer bypassed
Absolute AIN Voltage Limits
2
A
GND
+
0.1
AV
DD
−
0.1
V AIN1…AIN10 and AINCOM with buffer enabled
Absolute AIN Voltage Limits
2
A
GND
−
0.03
AV
DD
+
0.03
V AIN1…AIN10 and AINCOM with buffer bypassed
EXTERNAL REFERENCE INPUTS
REFIN(+) to REFIN(–) Voltage
2.5
V
REFIN refers to both REFIN and REFIN2
REFIN(+) to REFIN(–) Range
2
1 AV
DD
V REFIN refers to both REFIN and REFIN2
Average Reference Input Current ±1 µA/V Both ADCs enabled
Average Reference Input Current
Drift ±0.1 nA/V/°C
NOXREF Trigger Voltage 0.3 0.65 V
NOXREF (ADCSTAT.4) bit active if V
REF
> 0.3 V, and
inactive if V
REF
> 0.65 V
Common-Mode Rejection
DC Rejection 125 dB AIN = 1 V, range = ±2.56 V
50 Hz/60 Hz Rejection
2
90 dB
50 Hz/60 Hz ± 1 Hz, AIN = 1 V,
range = ±2.56 V, SF = 82
Normal Mode Rejection 50 Hz/60 Hz
2
75 dB
50 Hz/60 Hz ±1 Hz, AIN = 1 V, range = ±2.56 V,
SF = 52H, chop on, REJ60 on
100 dB
50 Hz ± 1 Hz, AIN = 1 V, range = ±2.56 V,
SF = 52H, chop on
67 dB
50 Hz/60 Hz ± 1 Hz, AIN = 1 V, range = ±2.56 V,
SF = 52H, chop off, REJ60 on
100
dB
50 Hz ± 1 Hz, AIN = 1 V, range = ±2.56 V,
SF = 52H, chop off
AUXILIARY ADC (ADuC845 Only)
Conversion Rate
5.4
105
Hz
Chop on
16.06 1365 Hz Chop off
No Missing Codes
2
24 Bits ≤26.7 Hz update rate, chop enabled
24 Bits 80.3 Hz update rate, chop disabled
Resolution See Table 19 and Table 21
Output Noise See Table 18 and Table 20 Output noise varies with selected update rates.
Integral Nonlinearity ±15 ppm of FSR 1 LSB
16
Offset Error
3
±3 µV Chop on
±0.25 LSB
16
Chop off
Offset Error Drift
2
10 nV/°C Chop on
200 nV/°C Chop off
Full-Scale Error
4
±0.5
LSB
16
Gain Error Drift
4
±0.5 ppm/°C
Power Supply Rejection 80 dB AIN = 1 V, range = ±2.56 V, chop enabled
80 dB AIN = 1 V, range = ±2.56 V, chop disabled
Footnotes at end of table.