32186 datasheet(879/1032 Pages) RENESAS

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RAM BACKUP MODE

19-7

32185/32186 Group Hardware Manual

Rev.1.10 REJ09B0235-0110 May 15, 07

19.3 Example of RAM Backup for Saving Power Consumption

19.3.2 RAM Backup State

Figure 19.3.3 shows the RAM backup state of the M32R/ECU. Figure 19.3.4 shows a RAM backup se-

quence. When the external circuit outputs "L," input on the SBI# or AD0INi pin is pulled "L." "L" on these

input pins generates a RAM backup signal (A and (a) in Figure 19.3.3). To enable RAM backup mode,

make the following settings:

(1) Create data for RAM check to verify after returning from RAM backup mode to normal mode

whether the RAM data has been retained normally ((b) in Figure 19.3.3).

(2) To materialize low-power operation, set all programmable input/output pins except port n for

input mode (or for output mode, with the output level fixed "L") ((c) in Figure 19.3.3).

(3) Set port n for input mode (B and (d) in Figure 19.3.3). This causes the transistor’s base voltage,

IB,to go "L," so that the power to all power supply pins except VDDE is shut off (C and D in

Figure 19.3.3).

By settings in (1) to (3), the VDDE pin voltage goes to 3.0–5.5 V and all other pin voltages drop to 0 V, and

the M32R/ECU is thereby placed in RAM backup mode ((d) in Figure 19.3.3).

Figure 19.3.3 RAM Backup State for Low Power Operation

"L"

(a)

(b)

(c)

(d)

"L"

DC IN

VREF0

SBI#

AD0INi

M32R/ECU

VDDE

AVCC0

VCCE,

VCCER

EXCVCC

EXCVDD

VCC-

BUS

3.3V or 5V

(5V or 3.3V)

Example of RAM backup processing

RAM backup signal

External circuit

Port n

(Note 1)

(Note 3)

RAM backup power supply

Regulator

Input

Output

Regulator

(Note 2)

Output

Note 1: This circuit outputs "L" during RAM backup.

Note 2: This port outputs "H" when the power is on, and is set for input mode

when in RAM backup mode (one of the port pins selected).

Note 3: These pins are used to detect a RAM backup signal.

Note 4: Determined by the input level on SBI# pin or AD0INi pin.

Note 5: Base voltage IB = 0 causes the power to all power supply pins except VDDE

to stop.

See A to D in the above explanation.

Generate a RAM backup signal

(Note 4)

Create data for

backup RAM check

Set the pin connecting to the

transistor's base (port n)

for input mode

(Note 5)

RAM backup mode

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