M32CSLASH8B datasheet(384/406 Pages) RENESAS

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M32C/8B Group

25. Usage Notes

Preliminary specification

Specifications in this manual are tentative and subject to change.

REJ09B0450-0050 Rev.0.50 Oct 31, 2008

Page 367 of 385

25.5.4.3

Suggestions to Reduce Power Consumption

The followings are suggestions to reduce power consumption when programming or designing systems.

Ports:

• Through current may flow into floating input pins. Set unassigned pins to input mode and connect them to

VSS via a resistor (pull down), or set unassigned pins to output mode and leave them open.

A/D converter:

• When the A/D conversion is not performed, set the VCUT bit in the AD0CON1 register to 0 (VREF not

connected). When the A/D conversion is performed, set the VCUT bit to 1 (VREF connection) and wait

μs or more to start the A/D conversion.

D/A converter:

• When the D/A conversion is not performed, set the DAiE bit (i = 0, 1) in the DACON register to 0 (output

disabled) and the DAi register to 00h.

Peripheral function clock stop:

• When entering wait mode from main clock mode, on-chip oscillator mode, or on-chip oscillator low-power

consumption mode, power consumption can be reduced by setting the CM02 bit in the CM0 register to 1 to

stop peripheral function clock source (fPFC). However, fC32 does not stop by setting the CM02 bit to 1.

• In low-speed mode or low-power consumption mode, do not set the CM02 bit to 1 (peripheral clock stops

in wait mode) when entering wait mode.

(Technical update: TN-M16C-69-0104)

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