M48T212A-85MH6 View Datasheet(PDF) - STMicroelectronics

Part Name

Description

Manufacturer

M48T212A-85MH6

3.3V TIMEKEEPER® CONTROLLER

STMicroelectronics 

M48T212A

POWER SUPPLY DECOUPLING

AND UNDERSHOOT PROTECTION

Note: ICC transients, including those produced by

output switching, can produce voltage fluctua-

tions, resulting in spikes on the VCC bus. These

transients can be reduced if capacitors are used to

store energy, which stabilizes the VCC bus. The

energy stored in the bypass capacitors will be re-

leased as low going spikes are generated or ener-

gy will be absorbed when overshoots occur.

A ceramic bypass capacitor value of 0.1µF is rec-

ommended in order to provide the needed filtering.

In addition to transients that are caused by normal

SRAM operation, power cycling can generate neg-

ative voltage spikes on VCC that drive it to values

below VSS 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, ST recom-

mends connecting a schottky diode from VCC to

VSS (cathode connected to VCC, anode to VSS).

(Schottky diode 1N5817 is recommended for

through hole and MBRS120T3 is recommended

for surface mount).

Figure 13. Supply Voltage Protection

VCC

0.1µF

VCC

DEVICE

VSS

AI02169

17/20

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