19
19-2
Rev.1.0
19.1 Outline
In RAM backup mode, the contents of the internal RAM are retained while the power is turned off.
RAM backup mode is used for the following two purposes:
• Back up the internal RAM data when the power is down
• Turn off the power to the CPU whenever necessary to save on the system's power
consumption
The 32R/E CPU is placed in RAM backup mode by applying a voltage of 2.0-3.3 V to the VDD pin
(provided for RAM backup) and 0 V to all other pins. During RAM backup mode, the contents of the
internal RAM are retained, while the CPU and internal peripheral I/O remain idle. Also, because all
pins except VDD are held low during RAM backup mode, power consumption in the system can
effectively reduced.
19.2 Example of RAM Backup when Power is Down
A typical circuit for RAM backup at power outage is shown in Figure 19.2.1. The following explains
how the RAM can be backed up by using this circuit as an example.
RAM BACKUP MODE
19.1 Outline
Figure 19.2.1 Typical Circuit for RAM Backup 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.
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)
Содержание 32172
Страница 20: ... This is a blank page 16 ...
Страница 21: ...1 1 Overview 1 2 Block Diagram 1 3 Pin Functions 1 4 Pin Layout CHAPTER 1 CHAPTER 1 OVERVIEW ...
Страница 44: ...1 1 24 Rev 1 0 This is a blank page Overview 1 4 Pin Layout ...
Страница 58: ...2 2 14 Rev 1 0 This is a blank page CPU 2 6 Data Formats ...
Страница 122: ...4 4 26 Rev 1 0 This is a blank page EIT 4 13 Precautions on EIT ...
Страница 200: ...7 7 6 Rev 1 0 This is a blank page RESET 7 4 Precautions to Be Taken Immediately after Reset ...
Страница 240: ...8 8 40 Rev 1 0 This is a blank page INPUT OUTPUT PORTS AND PIN FUNCTIONS 8 5 Precautions on Input Output Ports ...
Страница 298: ...9 9 58 Rev 1 0 This is a blank page DMAC 9 4 Precautions on Using DMAC ...
Страница 416: ...10 10 118 Rev 1 0 This is a blank page INPUT OUTPUT TIMERS 10 6 TOM Output Related 16 bit Timers ...
Страница 658: ...14 14 16 Rev 1 0 REAL TIME DEBUGGER RTD 14 4 Typical Connection with the Host This is a blank page ...
Страница 718: ...16 16 16 Rev 1 0 This is a blank page D A CONVERTERS 16 3 Functional Description of the D A Converters ...
Страница 766: ...18 18 22 Rev 1 0 WAIT CONTROLLER 18 3 Typical Operation of the Wait Controller This is a blank page ...
Страница 776: ...19 19 10 Rev 1 0 RAM BACKUP MODE 19 4 Exiting RAM Backup Mode Wakeup This is a blank page ...
Страница 777: ...CHAPTER 20 CHAPTER 20 OSCILLATION CIRCUIT 20 1 Oscillator Circuit 20 2 Clock Generator Circuit ...
Страница 782: ...20 20 6 Rev 1 0 OSCILLATION CIRCUIT 20 2 Clock Generator Circuit This is a blank page ...
Страница 856: ...23 23 26 Rev 1 0 This is a blank page ELECTRICAL CHARACTERISTICS 23 6 AC Characteristics ...
Страница 857: ...24 1 A D Conversion Characteristics CHAPTER 24 CHAPTER 24 STANDARD CHARACTERISTICS ...
Страница 859: ...Appendix 1 1 Dimensional Outline Drawing APPENDIX 1 APPENDIX 1 MECHANICAL SPECIFICATIONS ...
Страница 861: ...Appendix 2 1 M32R E Instruction Processing Time APPENDIX 2 APPENDIX 2 INSTRUCTION PROCESSING TIME ...
Страница 865: ...Appendix 3 1 Precautions about Noise APPENDIX 3 APPENDIX 3 PRECAUTIONS ABOUT NOISE ...