ADS7924_15 Datasheet, PDF (17/50 Pages) Texas Instruments – 4-Channel, MicroPOWER Analog-to-Digital Converter

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ADS7924
SBAS482B – JANUARY 2010 – REVISED SEPTEMBER 2015
Status
Input Multiplexer
Awake
t_PU
Acquire
Selected
Channel
t_ACQ
Convert
Selected
Channel
t_CONV
Acquire
Selected
Channel
t_ACQ
Convert
Selected
Channel
t_CONV
Acquire
Selected
Channel
t_ACQ
Convert
Selected
Channel
t_CONV
Selected Channel⁽¹⁾
Busy⁽²⁾
PWRCON⁽³⁾
(4)
(1) Same channel is continuously converted.
(2) Busy is an internal signal shown as active high that can be routed to the INT pin for external monitoring.
(3) PWRCON is shown enabled and active high.
(4) The mode begins on the trailing edge of the I²C acknowledge after writing to the MODECNTL register.
Figure 24. Example of Auto-Single Operation
7.4.1.6 Auto-Scan Mode
This mode automatically converts all the channels continuously, starting with the selected channel, as illustrated
in Figure 25. After the ADC Mode Control register is written, the power-up time (t_PU) is allowed to elapse. This
value can be set to '0' to effectively bypass if not needed. Before the conversion, an acquisition time (t_ACQ) is
allowed to elapse. t_ACQ time is programmable through the ACQCONFIG register, bits[4:0]. Sleep time (t_SLEEP) is
not used in this mode. The input multiplexer is automatically incremented as the conversions complete. If, for
example, the initial selected channel is CH2, the conversion order is CH2, CH3, CH0, CH1, CH2, CH3, and so
forth. until the mode is stopped. Data from the conversions are always put into the data register that corresponds
to a particular channel. For example, CH2 data always go in register DATA2_H and DATA2_L regardless of
conversion order.
This mode can be used with the onboard digital comparator to monitor the status of the input signals with little
support needed from a host microcontroller. TI suggests interrupting this mode and stopping the automatic
conversions, either by setting the mode to Idle or configuring the alarm to do so, before retrieving data.
Status
Input Multiplexer
Awake
t_PU
Acquire
First
Channel
t_ACQ
Convert
First
Channel
t_CONV
Selected Channel (First)
Acquire
Second
Channel
t_ACQ
Convert
Second
Channel
t_CONV
Next Channel
Acquire
Third
Channel
t_ACQ
Convert
Third
Channel
t_CONV
Next Channel
Acquire
Fourth
Channel
t_ACQ
Convert
Fourth
Channel
t_CONV
Next Channel
Acquire
First
Channel
t_ACQ
Convert
First
Channel
t_CONV
First Channel
Busy⁽¹⁾
PWRCON⁽²⁾
(3)
(1) Busy is an internal signal shown as active high that can be routed to the INT pin for external monitoring.
(2) PWRCON is shown enabled and active high.
(3) The mode begins on the trailing edge of the I²C acknowledge after writing to the MODECNTL register.
Figure 25. Auto-Scan Operation Example
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