Datasheet

ADuC845/ADuC847/ADuC848 Data Sheet
Rev. C | Page 4 of 108
SPECIFICATIONS
1
AV
DD
= 2.7 V to 3.6 V or 4.75 V to 5.25 V, DV
DD
= 2.7 V to 3.6 V or 4.75 V to 5.25 V, REFIN(+) = 2.5 V, REFIN(–) = AGND; AGND =
DGND = 0 V; XTAL1/XTAL2 = 32.768 kHz crystal; all specifications T
MIN
to T
MAX
, unless otherwise noted. Input buffer on for primary
ADC, unless otherwise noted. Core speed = 1.57 MHz (default CD = 3), unless otherwise noted.
Table 1.
Parameter Min Typ Max Unit Conditions
PRIMARY ADC
Conversion Rate 5.4 105 Hz Chop on (ADCMODE.3 = 0)
16.06 1365 Hz Chop off (ADCMODE.3 = 1)
No Missing Codes
2
24 Bits ≤26.7 Hz update rate with chop enabled
24 Bits ≤80.3 Hz update rate with chop disabled
Resolution (ADuC845/ADuC847) See Table 11 and Table 15
Resolution (ADuC848) See Table 13 and Table 17
Output Noise (ADuC845/ADuC847) See Table 10 and Table 14 μV (rms)
Output noise varies with selected update rates,
gain range, and chop status.
Output Noise (ADuC848) See Table 12 and Table 16 μV (rms)
Output noise varies with selected update rates,
gain range, and chop status.
Integral Nonlinearity ±15 ppm of FSR 1 LSB
16
Offset Error
3
±3 μV Chop on
Chop off, offset error is in the order of the noise
for the programmed gain and update rate
following a calibration.
Offset Error Drift vs. Temperature
2
±10 nV/°C Chop on (ADCMODE.3 = 0)
±200 nV/°C Chop off (ADCMODE.3 = 1)
Full-Scale Error
4
ADuC845/ADuC847 ±10 μV ±20 mV to ±2.56 V
ADuC848 ±10 μV ±20 mV to ±640 mV
±0.5 LSB
16
±1.28 V to ±2.56 V
Gain Error Drift vs. Temperature
4
±0.5 ppm/°C
Power Supply Rejection
80 dB AIN = 1 V, ±2.56 V, chop enabled
113 dB AIN = 7.8 mV, ±20 mV, chop enabled
80 dB AIN = 1 V, ±2.56 V, chop disabled
2
PRIMARY ADC ANALOG INPUTS
Differential Input Voltage Ranges
5, 6
Gain = 1 to 128
Bipolar Mode (ADC0CON1.5 = 0)
±1.024 ×
V
REF
/GAIN
V
V
REF
= REFIN(+) − REFIN(−) or
REFIN2(+) − REFIN2(−) (or Int 1.25 V
REF
)
Unipolar Mode (ADC0CON1.5 = 1)
0 – 1.024 ×
V
REF
/GAIN
V
V
REF
= REFIN(+) − REFIN(−) or
REFIN2(+) − REFIN2(−) (or Int 1.25 V
REF
)
ADC Range Matching ±2 μV AIN = 18 mV, chop enabled
Common-Mode Rejection DC Chop enabled, chop disabled
On AIN 95 dB AIN = 7.8 mV, range = ±20 mV
113 dB AIN = 1 V, range = ±2.56 V
Common-Mode Rejection
50 Hz/60 Hz
2
50 Hz/60 Hz ± 1 Hz, 16.6 Hz and 50 Hz update
rate, chop enabled, REJ60 enabled
On AIN 95 dB AIN = 7.8 mV, range = ±20 mV
90 dB AIN = 1 V, range = ±2.56 V
Footnotes at end of table.