AK9223MK Datasheet, PDF (9/16 Pages) Asahi Kasei Microsystems – Dual 1-Bit, 10MHz, 2nd-Order, ΔΣ Modulat

[AK9223]
Functional Descriptions
The AK9223 is a 2ch delta-sigma modulator. “0” and “1” data is output from its OUT pins and the level of
analog input signal is expressed by the density of this digital output.
A delta-sigma modulator shifts quantized noise to high band. A low-pass filter is needed at the output of
the AK9223. High band noise is filtered and the 1-bit data steam at a high sampling rate is converted into
a higher-bit data word at a lower rate by this low-pass filter (decimation). This digital filter can be
composed by a FPGA and etc. Figure 3 shows external circuit example. Recommended parts shown
below should be connected as close as possible to the device.
外部信号ソース
2.5V
2.5V
外部信号ソース
2.5V
2.5V
47Ω
47Ω
47Ω
47Ω
CA
=680pF
CA
=680pF
0.1uF
TEST0 TEST1
AIN0+
AIN0-
CLKO
OUT0
OUT1
DVDD
VSS5
REFI0
SEL
CLKI
AIN1+
AVDD
AIN1-
AVDD
REFI1
AVDD
REFO
VSS2
VSS4
VSS1
VSS3
AVDD
FPGA
or
ASIC
3V
0.1uF
3V
5V
5V
0.1uF
0.1uF
5V
5V
0.1uF
0.1uF
Figure 3. AK9223 Recommended External Circuits
AD conversion characteristics (speed and accuracy) are dependent on OSR (over sampling ratio) and
digital filter type. When the conversion rate is low, greater output accuracy can be achieved by increasing
the OSR. When the OSR is low, output accuracy is low but high speed conversion is available. With an
appropriate digital filter, the AK9223 is capable of AD conversion results that have a dynamic range
exceeding 86dB with an OSR = 256.
014010283-E-01
9
2015/01