M32C80 Datasheet, PDF (332/352 Pages) Renesas Technology Corp – 16/32-BIT SINGLE-CHIP MICROCOMPUTER M16C FAMILY / M32C/80 SERIES

M32C/80 Group
24. Precautions (Clock Generation Circuit)
24.4.6.3 Suggestions for Reducing Power Consumption
The followings are suggestions for reducing power consumption when programming or designing
systems.
Ports: I/O ports maintains the same state despite the microcomputer entering wait mode or stop
mode. Current flows through active output ports. Feedthrough current flows through input ports in a
high-impedance state. Set unassigned ports as input ports and stabilize electrical potential before
entering wait mode or stop mode.
A/D Converter: If the A/D conversion is not performed, set the VCUT bit in the AD0CON1 register
to "0" (no VREF connection). Set the VCUT bit to "1" (VREF connection) and wait at least 1µs before
starting the A/D conversion.
D/A Converter: Set the DAi bit (i=0, 1) in the DACON register to "0" (output disabled) and set the
DAi register to "0016" when the D/A conversion is not performed.
Peripheral Function Stop: Set the CM02 bit in the CM0 register while in wait mode to stop unnec-
essary peripheral functions. However, this does not reduce power consumption because the pe-
ripheral function clock (fc32) generating from the sub clock does not stop. When in low-speed mode
and low-power consumption mode, do not enter wait mode when the CM02 bit is set to "1" (periph-
eral clock stops in wait mode).
Rev. 1.00 Nov. 01, 2005 ^{Page 313} of 330
REJ09B0271-0100