IC for System Reset (battery backup) MM1134
MITSUMI
IC for System Reset (battery backup)
Monolithic IC MM1134
Outline
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This IC protects SRAM data by setting SRAM in backup mode (setting the CE pin of SRAM low and CE pin
high with CS signal) when supply voltage falls below a predetermined voltage (detection voltage 3.5V, 4.2V
typ.). Then, when supply voltage is getting lower, the main power supply is switched to a battery (switching
voltage 3.3V typ.) to enter backup mode with the battery. Meanwhile, when the power supply rises, first it
switches to the main power supply (switching voltage 3.3V typ.) from the battey backup mode, then switches
SRAM from backup mode to normal mode (by setting the CE pin of SRAM high and CE pin low). Data
damage can be reliably prevented by this signal processing.
ue
d
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on
tin
Features
di
sc
1. Power supply switching circuit (switching between the main power supply and a battery)
2. CS control for SRAM
Normal mode: Enables access to SRAM
Backup mode: Disables access to SRAM, low current consumption mode
3. With CS signal gate circuit
Characteristics
IO=100µA
uc
t
st
o
be
1. Battery back-up
1. Low IC current consumption (loss current)
2. Drop voltage inside IC (input/output voltage difference)
3. Reverse current (reverse leak current)
2. Normal operation
1. Drop voltage inside IC (input/output voltage difference)
2. Output voltage
VCC=5V
3. Battery-VCC switching voltage
4. Detection voltage (CS, CS, reset output)
Pr
od
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IO=50µA
IO=50mA
A : 3.5V typ.
B : 4.2V typ.
0.3µA typ.
0.3V typ.
0.1µA max.
0.2V typ.
4.8V typ.
3.3V typ.