Specifications

9
required. Hence,very low average
power consumption can be achieved,
even with a real time clock being
implemented in software.
• If no activity is required,but RAM
contents must be retained, H8/H8S
microcontrollers can be brought into
standby. In this mode the oscillator is
stopped and power consumption
drops to leakage current levels
(0. 01µA, typical at room
temperature). Two modes are
provided, software standby which
allows to retain IO ports and
hardware standby,which only retains
RAM. RAM retention voltage is
only 2V.
Some of these methods can be combined
to achieve outstanding average power
consumption values, while allowing high
performance operation at times of high
activity.
5.5V, 20MHz
Ta=R.T.
3.0V, 10MHz
60
40
20
0
Current consumption (mA)
Clock
ø/8 ø/4 ø/2 ø
10
50
30
80
70
Values based on sample measurements, values not guaranteed
As an example for such a combination,
let’s assume the DTC would be used to
move results of ADC conversions from
the ADC to a RAM buffer (e. g. 64
Byte). The CPU does not need to
process the data before acquisition of all
data has finished. This scenario would
allow to turn off all the modules,except
the ADC and the DTC,and put the
CPU into sleep during acquisition.
The resulting current would be only
appr. 3mA at 10MHz and 3V Vcc.
After acquisition of all 64 Byte has
ended,an interrupt wakes up the CPU
to process the data. While doing so the
software may choose to activate other
peripheral modules as required.
Please note that power consumption in
this scenario could be further reduced if
10MHz clock gives more performance
then needed. Typical Icc between 2mA
and 3mA are possible.
Figure 9