17
17-4
Ver.0.10
Figure 17.2.3 RAM Backup State at Power Outage
Note 1: Power outage is detected by the DC IN
(regulator input) voltage.
Note 2: These pins are used to detect a RAM backup
signal.
Note 3: This pin outputs a high when the power is on
and outputs a low when the power is down.
Note 4:
___
Determined by the input voltage level on SBI
pin or ADnINi pin.
Note 5: A d j u s t t h i s c a p a c i t a n c e t o p r o v i d t h e
necessary processing time in
➁
.
RAM BACKUP MODE
17.2 Example of RAM Backup when Power is Down
17.2.2 RAM Backup State
Shown in Figure 17.2.3 is the power outage RAM backup state of the M32R/E. When the power
supply goes down, the power supply monitor IC starts feeding current from the backup battery to
the M32R/E. Also, the power supply monitor IC's power outage detection pin outputs a low, causing
___
the SBI pin or ADnINi pin input to go low, which generates a RAM backup signal (
➀
in Figure
17.2.3). Whether the power is down or not must be determined with respect to the DC IN (regulator
input) voltage in order to allow for a software processing time at power outage.
To enable RAM backup mode, make the following settings.
(1) Create check data to verify after returning from RAM backup to normal mode whether the
RAM data has been retained normally (
➁
in Figure 17.2.3).
When the power supply to VCC goes down after settings in (1), the voltage applied to the VDD pin
becomes 2.0-3.3 V and voltages applied to all other pins drop to 0 V, and the M32R/E thereby
enters RAM backup mode (
➂
in Figure 17.2.3).
VREFn
SBI
ADnINi
M32R/E
C
Backup battery
VCC
VDD
VBB
VREF
Reference voltage for
power outage detection
Power outage
detection signal
Backup power supply
for power outage
Power supply
monitor IC
VDD
DC IN
Input
Output
Regulator
(5V system)
VCCI
AVCCn
OSC-VCC
OUT
VCCE
(Note 1)
Output
Regulator
(3.3V system)
(Note 3)
(Note 2)
3.3V
0V
(Note 4)
"L"
(Note 5)
2.0V - 3.3V
Example of RAM backup processing
Power goes down (Note 4)
Create check data
for backup RAM
➀
➁
➂
RAM backup mode
0V
0V
0V
0V
Summary of Contents for M32170F3VFP
Page 42: ...1 1 24 Ver 0 10 OVERVIEW 1 4 Pin Layout This is a blank page ...
Page 56: ...2 2 14 Ver 0 10 This is a blank page ...
Page 88: ...3 3 32 Ver 0 10 ADDRESS SPACE 3 7 Notes on Address Space This is a blank page ...
Page 270: ...9 9 40 Ver 0 10 DMAC 9 4 Precautions about the DMAC This is a blank page ...
Page 614: ...12 12 64 Ver 0 10 This is a blank page SERIAL I O 12 9 Precautions on Using UART Mode ...
Page 756: ...17 17 10 Ver 0 10 RAM BACKUP MODE 17 4 Exiting RAM Backup Mode Wakeup This is a blank page ...
Page 762: ...18 18 6 Ver 0 10 OSCILLATION CIRCUIT 18 2 Clock Generator Circuit This is a blank page ...
Page 831: ...CHAPTER 22 CHAPTER 22 TYPICAL CHARACTERISTICS 22 1 A D Conversion Characteristics ...
Page 833: ...Appendix 1 1 Dimensional Outline Drawing APPENDIX 1 APPENDIX 1 MECHANICAL SPECIFICATIONS ...
Page 841: ...Appendix 3 1 Precautions about Noise APPENDIX 3 APPENDIX 3 PRECAUTIONS ABOUT NOISE ...