Datasheet

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 25 26 27 28 29 30 31 32
DRDY
SCLK
DOUT
DataByte1(MSB) DataByte2(MSB 1)- DataByte4(LSB)
DIN
t
DDPD
ADS1281
www.ti.com SBAS378D –AUGUST 2007–REVISED JUNE 2010
READING DATA edge of SCLK and at the occurrence of the first falling
edge of SCLK, DRDY returns high. After 32 bits of
The ADS1281 has two ways to read conversion data:
data have been shifted out, further SCLK transitions
Read Data Continuous and Read Data By Command.
cause DOUT to go low. If desired, the read operation
may be stopped at 24 bits. The data shift operation
Read Data Continuous
must be completed within four CLK periods before
DRDY falls again or the data may be corrupted.
In the Read Data Continuous mode, the conversion
data are shifted out directly from the device without
The Read Data Continuous mode is the default data
the need for sending a read command. This mode is
mode for Pin mode. When a Stop Read Data
the default mode at power-on. This mode is also
Continuous command is issued, the DRDY output is
enabled by the RDATAC command. When DRDY
blocked but the ADS1281 continues conversions. In
goes low, indicating that new data are available, the
stop continuous mode, the data can only be read by
MSB of data appears on DOUT, as shown in
command.
Figure 47. The data are normally read on the rising
Figure 47. Read Data Continuous
Table 15. Timing Data for Figure 47
PARAMETER DESCRIPTION MIN TYP MAX UNITS
t
DDPD
DRDY to valid MSB on DOUT propagation delay
(1)
100 ns
(1) Load on DOUT = 20pF || 100kΩ.
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