MAX11410 Datasheet, PDF (32/95 Pages) Maxim Integrated Products – 24-Bit Multi-Channel Low-Power

MAX11410
24-Bit Multi-Channel Low-Power
1.9ksps Delta-Sigma ADC with PGA
Conversion Data Formats
The conversion data format is selected by the FORMAT
and U_BN bits in the CTRL register, as shown in Table 7a.
The Unipolar/Bipolar Select (U_BN) bit selects whether
the input range is bipolar or unipolar. A ‘1’ in this bit loca-
tion selects unipolar input range and a ‘0’ selects bipolar
input range. The Format Select (FORMAT) bit controls the
data format when in bipolar mode (U_BN =0). Unipolar
data is always in straight binary format. The FORMAT
bit has no effect in Unipolar mode (U_BN = 1). In bipolar
mode, if the FORMAT bit = 1, then the data format is off-
set binary. If the FORMAT bit = 0, then the data format is
two’s complement.
Digital Filter
The configurable digital filter has selectable notch fre-
quencies (50 and 60, 50, 60, or SINC4) and selectable
data rates. The filter rejection and frequency response is
determined by the LINEF and RATE field settings in the
FILTER register.
Table 8. Conversion Data Formats
The simultaneous 50Hz/60Hz rejection FIR filter provides
well over 90dB rejection of 50Hz and 60Hz at 16sps and
significant rejection of their harmonics. The 50Hz and
60Hz FIR filter settings provide a lower level of attenua-
tion for those frequencies, but at a faster conversion time
than available with the simultaneous 50Hz/ 60Hz FIR fil-
ter. The SINC4 setting enables a 4th-order SINC filter that
can operate at continuous data rates up to 1920sps, with
the first notch at the continuous data rate. The available
conversion rates are determined by the LINEF setting.
Note that data rate for a given RATE setting is determined
by the type of conversion selected in the CONV_START
or GP_CONV register, based on a nominal clock period
of 2.456MHz. In continuous conversion mode with LINEF
= 11, the digital filter has a settling time of 4x the sample
rate. The first sample will not be available until the expi-
ration of that settling time. Subsequent samples will be
available at the listed sample rate. The filter sample rate
is determined by the combination of LINEF and RATE
settings, as well as the type of conversion launched by
the CONV_START command. Data rates and rejection
specifications for all settings are summarized below.
MODE
FORMAT
U_BN
Code Description
Positive Full Scale
Positive FS – 1LSB
Positive Mid-Scale
Positive 1 LSB
Negative 1 LSB
Negative FS + 1LSB
Negative FS
BIPOLAR MODE
1
0
Input Voltage
(V_AINP-V_AINN)
≥VREF
Offset Binary
0xFFFFFF
V_REF(1-1/(2²³-1))
V_REF(1+1/(2²³-1))/2
V_REF/(2²³-1)
0V
0xFFFFFE
0xC00000
0x800001
0x800000
- V_REF/(2²³-1)
-V_REF
- V_REF(1+1/(2²³-1))
0x7FFFFF
0x000001
0x000000
0
0
2’s Complement
0x7FFFFF
0x7FFFFE
0x400000
0x000001
0x000000
0xFFFFFF
0x800001
0x800000
UNIPOLAR MODE
X
1
Input Voltage
(V_AINP-V_AINN)
≥V_REF
V_REF(1-1/(2²⁴-1))
V_REF(1+1/(2²⁴-1))/2
VREF/(2²⁴-1)
Straight Binary
(Unipolar Mode)
0xFFFFFF
0xFFFFFE
0x800000
0x000001
0V
0x000000
<0V
0x000000
<0V
0x000000
<0V
0x000000
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