M40Z300, M40Z300W

10/16

switching, can produce voltage fluctuations, re-

can be reduced if capacitors are used to store en-

stored in the bypass capacitors will be released as

low going spikes are generated or energy will be

absorbed when overshoots occur.

A ceramic bypass capacitor value of 0.1µF (as

shown in figure 8) is recommended in order to pro-

vide the needed filtering.

In addition to transients that are caused by normal

SRAM operation, power cycling can generate neg-

spikes can cause data corruption in the SRAM

while in battery backup mode. To protect from

these voltage spikes, STMicroelectronics recom-

Schottky diode 1N5817 is recommended for

through hole and MBRS120T3 is recommended

for surface mount.

Figure 7. Address-Decode Time

Note: During system design, compliance with the SRAM timing parameters must comprehend the propagation delay

AI02551

A, B

E

E1CON-E4CON

tAS

tEDH or tEDL

tEDL

Figure 8. Supply Voltage Protection

AI00622

VCC

0.1

µF

DEVICE

VCC

VSS

Table 8. Battery Table

Part Number

Description

Package

M4Z28-BR00SH

Lithium Battery (48mAh) SNAPHAT

SH

M4Z32-BR00SH

Lithium Battery (120mAh) SNAPHAT

SH