inactive.

Figure 4 shows the L4901A with a back up battery

clock and a stand by type N-MOS

µP. The reset

output makes sure that the RAM is forced into the

low consumption stand by state, so the access to

memory is inhibit and the back up battery voltage

cannot drop so low that memory contents are cor-

rupted.

In this case the main on-off switch disconnects both

regulators from the supply battery.

The L4901A is also ideal for microcomputer sys-

tems using battery backup CMOS static RAMs. As

shown in Figure 5 the reset output is used both to

Figure 4

Figure 5

L4901A

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