Datasheet

31
www.ti.com
TSC2000
SBAS257
FIGURE 24. AUX1 Measurement Process.
FIGURE 25. AUX2 Measurement Process.
FIGURE 26. Port Scan Mode.
Host Writes
A/D Converter
Control Register
Start Clock
Port Scan
Done
Yes
No
Is Data
Averaging Done
Yes
No
Is Data
Averaging Done
Store Battery Input 1
in BAT1 Register
Power Down
A/D Converter
Power Up
A/D Converter
Power Up Reference
Convert
Battery Input 1
Store Battery Input 2
in BAT2 Register
Convert
Battery Input 2
Yes
No
Is Data
Averaging Done
Yes
No
Is Data
Averaging Done
Store Auxiliary Input 1
in AUX1 Register
Convert
Auxiliary Input 1
Store Auxiliary Input 2
in AUX2 Register
Convert
Auxiliary Input 2
Issue Data Available
Power Down Reference
Turn Off Clock
Host Writes
A/D Converter
Control Register
Start Clock
Auxiliary Input 2
Done
Yes
No
Is Data
Averaging Done
Store Auxiliary Input 2
in AUX2 Register
Power Down
A/D Converter
Power Up
A/D Converter
Power Up Reference
Convert
Auxiliary Input 2
Issue Data Available
Power Down Reference
Turn Off Clock
Host Writes
A/D Converter
Control Register
Start Clock
Auxiliary Input 1
Done
Yes
No
Is Data
Averaging Done
Store Auxiliary Input 1
in AUX1 Register
Power Down
A/D Converter
Power Up
A/D Converter
Power Up Reference
Convert
Auxiliary Input 1
Issue Data Available
Power Down Reference
Turn Off Clock
OPERATION—AUXILIARY MEASUREMENT
The two auxiliary voltage inputs can be measured in much
the same way as the battery inputs, as shown in Figures 24
and 25. Applications might include external temperature
sensing, ambient light monitoring for controlling the back-
light, or sensing the current drawn from the battery.
OPERATION—PORT SCAN
If making measurements of all the analog inputs (except the
touch screen) is desired on a periodic basis, the Port Scan
mode can be used. This mode causes the TSC2000 to
sample and convert both battery inputs and both auxiliary
inputs. At the end of this cycle, the battery and auxiliary result
registers will contain the latest values. Thus, with one write
to the TSC2000, the host can cause four different measure-
ments to be made.
The flowchart for this process is shown in Figure 26. The time
needed to make a complete port scan is given by:
t 7.5 s + t + 4N N
1
f
4.4 s
READING
REF
AVG BITS
CONV
=µ +µ
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
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