Datasheet

Status
Awake
Acquire
Second
Channel
Acquire
Third
Channel
Acquire
Fourth
Channel
Acquire
First
Channel
Busy
(1)
Convert
Channel
First
PWRCON
(2)
Convert
Channel
Second
Convert
Channel
Third
Convert
Channel
Fourth
InputMultiplexer
SelectedChannel(First)
NextChannel NextChannel NextChannel FirstChannel
t
PU
t
ACQ
t
CONV
t
ACQ
t
ACQ
t
ACQ
t
ACQ
t
CONV
t
CONV
t
CONV
t
CONV
Convert
Channel
First
Acquire
First
Channel
(3)
ADS7924
SBAS482A –JANUARY 2010–REVISED MAY 2010 www.ti.com
Auto-Scan Mode
is stopped. Data from the conversions are always put
into the data register that corresponds to a particular
This mode automatically converts all the channels
channel. For example, CH2 data always go in register
continuously, starting with the selected channel, as
DATA2_H and DATA2_L regardless of conversion
illustrated in Figure 26. After the ADC Mode Control
order.
register is written, the power-up time (t
PU
) is allowed
to elapse. This value can be set to '0' to effectively
This mode can be used with the onboard digital
bypass if not needed. Before the conversion, an
comparator to monitor the status of the input signals
acquisition time (t
ACQ
) is allowed to elapse. t
ACQ
time
with little support needed from a host microcontroller.
is programmable through the ACQCONFIG register,
It is suggested to interrupt this mode and stop the
bits[4:0]. Sleep time (t
SLEEP
) is not used in this mode.
automatic conversions, either by setting the mode to
The input multiplexer is automatically incremented as
Idle or configuring the alarm to do so, before
the conversions complete. If, for example, the initial
retrieving data.
selected channel is CH2, the conversion order is
CH2, CH3, CH0, CH1, CH2, CH3, etc. until the mode
(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 I
2
C acknowledge after writing to the MODECNTL register.
Figure 26. Auto-Scan Operation Example
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