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SBAS286A − JUNE 2003 − REVISED MARCH 2004
Data Ready
Standby Mode
DRDY/DOUT
SCLK
23
22
21
0
23
Start Conversion
1
24
t9
t10
t11
SYMBOL DESCRIPTION
MIN
MAX
UNITS
(1)
(1)
t
SCLK high after DRDY/DOUT goes low to activate Standby mode
Standby mode activation time
0
8.272
8.304
28.1
ms
ms
ms
9
t
10
8.272
27.7
(1)
t
Data ready after exiting Standby mode
11
(2)
Values given for f
CLK
= 2MHz. For different f frequencies, scale proportional to CLK period.
CLK
Figure 28. Standby Mode Timing (can be used for single conversions)
Data Ready After Calibration
Standby Mode
DRDY/DOUT
SCLK
23
22
21
0
23
Begin Calibration
1
24
25
t10
t12
SYMBOL DESCRIPTION
(1)
MIN
MAX
UNITS
t
12
Data ready after exiting Standby mode and calibration
78.8
79.7
ms
(1)
Values given for f = 2MHz. For different f
frequencies, scale proportional to CLK period.
CLK CLK
Figure 29. Standby Mode with Self-Calibration Timing (can be used for single conversions)
high to stop the ADS1224 from converting and re-enter
Standby mode. Continue to hold SCLK high until ready
to start the next conversion. Operating in this fashion
greatly reduces power consumption since the
ADS1224 is shut down while idle between conversions.
Self-calibrations can be performed prior to the start of
the single conversions by using the waveform shown in
Figure 29.
SINGLE CONVERSIONS
When only single conversions are needed, Standby
mode can be used to start and stop the ADS1224. To
make a single conversion, first enter the Standby mode
holding SCLK high. Now, when ready to start the
conversion, take SCLK low. The ADS1224 wakes up
and begins the conversion. Wait for DRDY/DOUT to go
low, and then retrieve the data. Afterwards, take SCLK
16
BB [ BURR-BROWN CORPORATION ]
