22
FN3612.10
June 27, 2006
result in conversion X + 1 data overwriting conversion X
results. For example, with f
OSC
= 10MHz, f
N
= 2kHz, the
read cycle must start within 1/2000 - 128(1/10
6
) = 487μs
after DRDY
went low.
2) The Data Output Register read cycle for conversion X
must be completed within 2(1/f
N
)-1440(1/f
OSC
) after DRDY
initially goes active low. If the read cycle for conversion X is
not complete within this time the results of conversion X + 1
are lost and results from conversion X + 2 are now stored in
the data output word buffer.
Completing the Data Output Register read cycle inactivates
the DRDY
interrupt. If the one word data output buffer is full
when this read is complete this data will be immediately
transferred to the Data Output Register and a new DRDY
interrupt will be issued after the minimum DRDY
pulse high
time is met.
Writing the Control Register
If data is written to byte 2 and/or byte 1 of the Control
Register the DRDY
output is taken high and the device re-
calibrates if written to a calibration mode. This action is taken
because it is assumed that by writing byte 2 or byte 1 that
the user either reprogrammed the filter or changed modes of
the part. However, if a single data byte is written to byte 0, it
is assumed that the gain has NOT been changed. It is up to
the user to re-calibrate the HI7190 after the gain has been
changed by this method. It is recommended that the entire
Control Register be written to when changing the selected
gain. This ensures that the part is re-calibrated before the
DRDY
signal goes low indicating valid data is available.
Offset Calibration Register
The Offset Calibration Register is a 24-bit register containing
the offset correction factor. This register is indeterminate on
power-up but will contain a Self Calibration correction value
after a RESET
has been applied.
The Offset Calibration Register holds the value that corrects
the filter output data to all 0’s when the analog input is 0V.
Positive Full Scale Calibration Register
The Positive Full Scale Calibration Register is a 24-bit
register containing the Positive Full Scale correction
coefficient. This coefficient is used to determine the positive
gain slope factor. This register is indeterminate on power-up
but will contain a Self Calibration correction coefficient after
a RESET
has been applied.
Negative Full Scale Calibration Register
The Negative Full Scale Calibration Register is a 24-bit
register containing the Negative Full Scale correction
coefficient. This coefficient is used to determine the negative
gain slope factor. This register is indeterminate on power-up
but will contain a Self Calibration correction coefficient after
a RESET
has been applied.
BYTE 2
MSB22212019181716
O23 O22 O21 O20 O19 O18 O17 O16
BYTE 1
15 14 13 12 11 10 9 8
O15 O14 O13 O12 O11 O10 O9 O8
BYTE 0
7654321LSB
O7 O6 O5 O4 O3 O2 O1 O0
BYTE 2
MSB22212019181716
P23P22P21P20P19P18P17P16
BYTE 1
15 14 13 12 11 10 9 8
P15 P14 P13 P12 P11 P10 P9 P8
BYTE 0
7654321LSB
P7 P6 P5 P4 P3 P2 P1 P0
BYTE 2
MSB22212019181716
N23 N22 N21 N20 N19 N18 N17 N16
BYTE 1
15 14 13 12 11 10 9 8
N15 N14 N13 N12 N11 N10 N9 N8
BYTE 0
7654321LSB
N7 N6 N5 N4 N3 N2 N1 N0
HI7190
