System Reset (with battery back-up) MM1027, 1081
MITSUMI
System Reset (with battery back-up)
Monolithic IC MM1027, 1081
Outline
These ICs were developed for STATIC-RAM (S-RAM) battery back-up, and have built-in switching circuit for
main power supply and battery, back-up timing circuit and battery checker.
Power ON/OFF and momentary power interruptions can damage S-RAM data on equipment that contains an
S-RAM. These ICs switch the S-RAM to back-up mode (CS signal makes S-RAM CE pin low and CE pin high)
when power supply voltage goes below a set voltage (detection voltage 4.2V typ., variable), preventing
damage to data. Further, when power supply voltage drops, these ICs switch from main power supply to
battery back-up (switching voltage 3.3V typ.). Then, when power supply voltage rises, they first switch the SRAM from battery back-up state to main power supply (switching voltage 3.3V typ.), and 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. The CS signal also can absorb power supply chattering and
roughness through the external capacitor.
There is a built-in battery checker to monitor the back-up battery voltage, and this circuit is turned ON/OFF by
the control pin.
ue
d
-------------------------
on
tin
------------------------
sc
Features
IO=10µA
Pr
od
uc
t
st
o
be
di
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
MM1027
Drop voltage inside IC (input/output voltage difference)
Output voltage
VCC=5V
Current consumption
D.CONT OPEN
External transistor drive current
MM1081
Drop voltage inside IC (input/output voltage difference)
Output voltage
VCC=5V
Current consumption
External transistor drive current (for output current increase)
TC source current
3. Battery-Vcc switching voltage
4. Detection voltage (CS, CS) variable
5. Battery checker 1
X type
N type
6. Battery checker 2
X type
N type
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Package
TSOP-20A (MM1027XV, MM1027NV, MM1081XV)
SOP-16A (MM1027XF, MM1027NF)
DIP-16A (MM1027XD)
0.3µA typ.
0.2V typ.
0.1µA max.
IO=70mA
IO=10mA
0.2V typ.
4.8V typ.
3.0mA max.
25mA typ.
IO=120mA
IO=120mA
0.25V typ.
4.75V typ.
350µA max.
25mA typ.
3.0µA typ.
3.3V typ.
4.2V typ.
2.70V typ.
2.50V typ.
2.55V typ.
2.35V typ.
