MAX11902 Datasheet, PDF (20/29 Pages) Maxim Integrated Products – Fully Differential SAR ADC

MAX11902
18-Bit, 1Msps, Low-Power,
Fully Differential SAR ADC
In the split reading mode, the data is read during the track
phase and the following SAR conversion phase. Figure 7
shows the descriptive timing diagram.
At higher sampling rates, the track time may not be long
enough to allow reading all 18 bits of data. In this case,
the data read can be started in track mode, and then
continued in the subsequent SAR conversion phase. Note
that the read operation must be completed before DOUT
goes low, signaling the end of the SAR conversion phase.
Also note that no SCLK pulses should be applied close to
the sampling edge (rising edge of CNVST), to safeguard
the sampling edge from digital noise (see the Quiet Time
specification t₁₀). This split reading feature can be used
to accommodate slower SPI clocks.
SPI Timing Diagram
Figure 8 shows the typical digital SPI interface connection
between the MAX11902 and host processor.
The dashed connections are optional.
Figure 9 shows the timing diagram for configuration reg-
isters.
Figure 10 shows the timing diagram for data output read-
ing after conversion.
SAR Conversion
1/Sample Rate
CNVST
Sample 1
Track
SCLK
DOUT
MSB MSB-1
Read Data
Sample 2
SAR Conversion
1/Sample Rate
Quiet Time
Track
Read Data
Sample 1
Reading sample 1
LSB+1 LSB
Sample 2
MSB MSB-1
Figure 7. Split Read Mode
MAX11905
DIN
SCLK
DOUT
Figure 8. SPI Interface Connection
CNVST
Host Processor
DOUT
SCLK
DIN
IRQ
CNVST
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