M48T59 查看數據表（PDF） - STMicroelectronics
零件编号
产品描述 (功能)
生产厂家
M48T59 Datasheet PDF : 29 Pages
| |||
M48T59, M48T59Y, M48T59V*
Century Bit
Bit D5 and D4 of Clock Register 1FFCh contain
the CENTURY ENABLE Bit (CEB) and the CEN-
TURY Bit (CB). Setting CEB to a '1' will cause CB
to toggle, either from a '0' to '1' or from '1' to '0' at
the turn of the century (depending upon its initial
state). If CEB is set to a '0,' CB will not toggle.
Note: The WRITE Bit must be set in order to write
to the CENTURY Bit.
Initial Power-on Defaults
Upon application of power to the device, the fol-
lowing register bits are set to a '0' state: WDS;
BMB0-BMB4; RB0-RB1; AFE; ABE; W; R; FT (see
Table 7.).
Table 7. Default Values
Condition
W
R
Initial Power-up
(Battery Attach for SNAPHAT)(2)
0
0
Subsequent Power-up / RESET(3)
0
0
Power-down(4)
0
0
Note: 1. WDS, BMB0-BMB4, RBO, RB1.
2. State of other control bits undefined.
3. State of other control bits remains unchanged.
4. Assuming these bits set to '1' prior to power-down.
WATCHDOG
FT
AFE
ABE
Register(1)
0
0
0
0
0
0
0
0
0
1
1
0
VCC Noise And Negative Going Transients
ICC transients, including those produced by output
switching, can produce voltage fluctuations, re-
sulting in spikes on the VCC bus. These transients
can be reduced if capacitors are used to store en-
ergy which stabilizes the VCC 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 ceramic by-
pass capacitor value of 0.1µF (as shown in Figure
14.) is recommended in order to provide the need-
ed 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, it is recommended to con-
nect 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 14. Supply Voltage Protection
VCC
0.1µF
VCC
DEVICE
VSS
AI02169
18/29
Share Link: 