Intermec CK30

Chapter 4 — Theory of Operation
Power management software on the PXA255 uses the battery voltage and
temperature data for temperature-compensated fuel gauging and low-
battery detection. Three levels of battery status are indicated through an
icon in the status bar:
Percentage of Charge Remaining Icon Displayed
67% to 100% charge remaining (No icon displays)
34% to 67% charge remaining
1% to 33% charge remaining
0% charge remaining
Low-Battery Handling
The first three battery status thresholds are defined in software; the final
critically low battery threshold is based on hardware comparator U36.
Low-Battery Thresholds
State Temp (ºC)
Threshold to
Enter State
Threshold to Exit
State
Action
Software 2/3
capacity threshold
< 0°C
10°C
20°C
30°C
40°C
50°C
<= 7.73V*
<= 7.78V
<= 7.83V
<= 7.87V
<= 7.92V
<= 7.97V
>= 7.83V*
>= 7.88V
>= 7.93V
>= 7.97V
>= 8.02V
>= 8.07V
Battery at approximately 67%
capacity; “2/3” battery status
icon is displayed.
Software 1/3
capacity threshold
< 0°C
10°C
20°C
30°C
40°C
50°C
<= 7.07V*
<= 7.16V
<= 7.25V
<= 7.35V
<= 7.44V
<= 7.53V
>= 7.17V*
>= 7.26V
>= 7.35V
>= 7.45V
>= 7.54V
>= 7.63V
Battery at approximately 33%
capacity; “1/3” battery status
icon is displayed.
Software low-
battery threshold
< 0°C
10°C
20°C
30°C
40°C
50°C
<= 6.4V*
<= 6.54V
<= 6.68V
<= 6.82V
<= 6.96V
<= 7.10V
>= 6.5V*
>= 6.64V
>= 6.78V
>= 6.92V
>= 7.06V
>= 7.20V
Battery at 0%; “Empty”
battery status icon is displayed,
and the red LED turns on.
Critically low
battery
< 0°C
10°C
20°C
30°C
40°C
50°C
<= 5.82V**
<= 5.96V
<= 6.15V
<= 6.31V
<= 6.45V
<= 6.55V
>= 6.41V**
>= 6.55V
>= 6.69V
>= 6.80V
>= 6.88V
>= 6.94V
Critically low battery. U36
asserts interrupt
BATT_FAULT_IRQ to start
a Suspend. This state must be
exited before the CK30 is
allowed to resume.
* These temperature ranges are approximate because the Vbat temperature compensation is not calibrated at
manufacture. Also, because the battery level is averaged over 10 samples at 3-second intervals, it may take up to
30 seconds for a threshold crossing to take effect.
** These temperature ranges are approximate because the Vbat temperature compensation is done in hardware.
CK30 Handheld Computer Service Manual 61