33972_09 Datasheet, PDF (17/32 Pages) Freescale Semiconductor, Inc – Multiple Switch Detection Interface with Suppressed Wake-up

FUNCTIONAL DEVICE OPERATION
OPERATIONAL MODES
Table 12. Analog Channel
Bits 43210
Analog Channel Select
00000
00001
00010
00011
00100
00101
00110
00111
01000
01001
01010
01011
01100
01101
01110
01111
10000
10001
No Input Selected
SG0
SG1
SG2
SG3
SG4
SG5
SG6
SG7
SG8
SG9
SG10
SG11
SG12
SG13
SP0
SP1
SP2
10010
SP3
10011
SP4
10100
SP5
10101
SP6
10110
SP7
CALIBRATION OF TIMERS
In cases where an accurate time base is required, the user
may calibrate the internal timers using the calibration
command (Table 13). After the 33972 device receives the
calibration command, the device expects 512 μs logic [0]
calibration pulse on the CS pin. The pulse is used to calibrate
the internal clock. No other SPI pins should transition during
this 512 μs calibration pulse. Because the oscillator
frequency changes with temperature, calibration is required
for an accurate time base. Calibrating the timers has no affect
on the quiescent current measurement. The calibration
command simply makes the time base more accurate. The
calibration command may be used to update the device on a
periodic basis.
Table 13. Calibration Command
Calibration Command
Command Bits
23 22 21 20 19 18 17 16 15 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0
0 0 0 0 1 0 1 1XXXXXXXXXXXXXXXX
Analog Integrated Circuit Device Data
Freescale Semiconductor
33972
17