M37517F8HP Datasheet, PDF (40/98 Pages) Renesas Technology Corp – SINGLE-CHIP 8-BIT CMOS MICROCOMPUTER

7517 Group
Calibration mode
Setting the current integrate mode bit “1”, the input of level shift
circuit is connected to internal AVSS or 0.1V for reference voltage.
When the calibration selection bit is “00”, both of plus and GND in-
put of level shift circuit are connected to internal AVSS, and zero
calibration is operated. When the calibration selection bit is “01”,
plus input of level shift circuit is connected to internal 0.1V refer-
ence voltage, and GND input of level shift circuit is connected to
internal AVSS, and then full calibration for discharge state is op-
erated. When the calibration selection bit is “10”, plus input of
level shift circuit is connected to internal AVSS, and GND input of
level shift circuit is connected to 0.1V reference voltage, and the
full calibration for charge state is operated. The calibration pe-
riod can be selected by calibration period selection bit among
15.625 ms, 31.25 ms, 62.5 ms, 125.0 ms. The calibration starts
at beginning of next integrate period, after setting the current in-
tegrate mode bit “1”.
Integrate period 125 ms
VINF input
Current integrate
mode bit
Set calibration complete
flag to “1”.
Counter latch content flag
Integrate period 125 ms
Calibration
15.625 ms -125 ms
Current integrate mode
Level shift circuit
out put
Integrator output
Discharge comparator
Discharge counter
Discharge counter latch
0
1
23
Count value of last
integrate period
3 (Calibration result)
Integrate period 125 ms
Count value of last integrate period *
* Except calibration period
Integrate period 125ms
Integrator output
AD conversion mode bit
Discharge comparator
Discharge signal
for integrator
AD conversion
completion bit
Integrate period 125ms
Calibration
15.625 ms -125 ms
AD conversion execute
Fig. 46 Calibration timing
Rev.1.01 Aug 02, 2004 page 40 of 96