Datasheet

31
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TSC2200
SBAS191F
FIGURE 21. Battery Measurement Functional Block Diagram.
FIGURE 22. V
BAT1
Measurement Process.
FIGURE 23. V
BAT2
Measurement Process.
OPERATION—BATTERY MEASUREMENT
An added feature of the TSC2200 is the ability to monitor the
battery voltage on the other side of a voltage regulator
(DC/DC converter), as shown in Figure 21. The battery
voltage can vary from 0.5V to 6V while maintaining the
voltage to the TSC2200 at 2.7V, 3.3V, etc. The input voltage
(V
BAT1
or V
BAT2
) is divided down by 4 so that a 6.0V battery
voltage is represented as 1.5V to the A/D converter. This
simplifies the multiplexer and control logic. In order to mini-
mize the power consumption, the divider is only ON during
the sampling of the battery input.
Flowcharts that detail the process of making a battery input
reading are shown in Figures 22 and 23.
The time needed to make temperature, auxiliary, or battery
measurements is given by:
(7)
t 2.625 s + t N N
1
f
s
READING
REF
AVG BITS
CONV
=µ + • +µ






44.
where t
REF
is the reference delay time as given in Table XVII.
V
DD
V
BAT
7.5kΩ
2.5kΩ
DC/DC
Converter
Battery
0.5V
to
6.0V
0.125V to 1.5V
2.7V
+
Host Writes
A/D Converter
Control Register
Start Clock
Battery Input 1
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
Issue Data Available
Power Down Reference
Turn Off Clock
Host Writes
A/D Converter
Control Register
Start Clock
Battery Input 2
Done
Yes
No
Is Data
Averaging Done
Store Battery Input 2
in BAT2 Register
Power Down
A/D Converter
Power Up
A/D Converter
Power Up Reference
Convert
Battery Input 2
Issue Data Available
Power Down Reference
Turn Off Clock