Outline

These ICs protect S-RAM data in back-up mode (CS signal makes R-SAM CE pin low and CE pin 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.

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

Applications

1. Memory cards (S-RAM cards)

2. PCs, word processors

3. Fax machines, photocopiers, other office equipment

4. Sequence controllers, other FA equipment

5. Video games and other equipment with S-RAMs