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MITSUMI
System Reset (with battery back-up) MM1026, 1245, 1080, 1134
System Reset (with battery back-up)
Monolithic IC MM1026, 1245, 1080 ,1134
Outline
These ICs protect S-RAM data in back-up mode (CS signal makes R-SAM CE pin low and
high) when power supply voltage goes below a certain set voltage (detection voltage 3.5V, 4.2V or 4.5V typ.).
Further, it switches from main power supply to battery back-up when power supply voltage drops.
Conversely, when power supply rises, it first switches the S-RAM from battery back-up to main power supply
(switching voltage 3.3V typ.), then from back-up mode to normal mode (CS signal makes S-RAM CE pin high
and CE pin low). These signal processes provide reliable protection against data damage.
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pin
Features
MM1026
Power supply switching circuit (switching between main power supply and battery)
CS control for S-RAM (normal mode : S-RAM can be accessed; back-up mode: S-RAM can not be
accessed low current consumption mode)
Reset output
MM1245
Power supply switching circuit
CS control for S-RAM
CS control signal delay, power supply line chattering removal approx. 1s max.
Supply current from main power supply can be increased by external power transistor
MM1080
Power supply switching circuit
CS control for S-RAM
Low current consumption 60μA typ.
MM1134
Power supply switching circuit
CS control for S-RAM
Gate circuit with CS signal
Characteristics
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 V
CC
=5V
3. Battery-V
CC
switching voltage
4. Detection voltage (CS,
0.3μA typ.
0.3V typ.
0.1μA max.
I
O
=100μA
I
O
=50μA
I
O
=50mA
0.2V typ.
4.8V typ.
3.3V typ.
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, reset output)
A : 3.5V typ.
B : 4.2V typ.
C : 4.5V typ.