Datasheet

Clock operations M48T58, M48T58Y
20/33 Doc ID 2412 Rev 8
6.7 V
CC
noise and negative going transients
I
CC
transients, including those produced by output switching, can produce voltage
fluctuations, resulting in spikes on the V
CC
bus. These transients can be reduced if
capacitors are used to store energy which stabilizes the V
CC
bus. The energy stored in the
bypass capacitors will be released as low going spikes are generated or energy will be
absorbed when overshoots occur. A bypass capacitor value of 0.1 µF (as shown in
Figure 10) is recommended in order to provide the needed filtering.
In addition to transients that are caused by normal SRAM operation, power cycling can
generate negative voltage spikes on V
CC
that drive it to values below V
SS
by as much as
one volt. These negative spikes can cause data corruption in the SRAM while in battery
backup mode. To protect from these voltage spikes, it is recommended to connect a
Schottky diode from V
CC
to V
SS
(cathode connected to V
CC
, anode to V
SS
). Schottky diode
1N5817 is recommended for through hole and MBRS120T3 is recommended for surface
mount.
Figure 10. Supply voltage protection
AI02169
V
CC
0.1µF DEVICE
V
CC
V
SS