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参数资料
| 型号： | M48T37V-70MH1 |
| 厂商： | 意法半导体 |
| 英文描述： | 3.3V-5V 256 Kbit 32Kb x8 TIMEKEEPER SRAM |
| 中文描述： | 3.3 - 5V的256千位的32KB的SRAM x8计时器 |
| 文件页数： | 15/20页 |
| 文件大小： | 128K |
| 代理商： | M48T37V-70MH1 |
15/20
M48T37Y, M48T37V
BATTERY LOW FLAG
The M48T37Y/37V automatically performs period-
ic battery voltage monitoring upon power-up. The
Battery Low Flag (BL), Bit D4 of Flags Register
7FF0h, will be asserted high if the SNAPHAT bat-
tery is found to be less than approximately 2.5V.
The BL flag will remain active until completion of
battery replacement and subsequent battery low
monitoring tests, during the next power-up se-
quence.
If a battery lowis generated during a power-up se-
quence, this indicates that the battery voltage is
below 2.5V (approximately), which may be insuffi-
cient to maintain data integrity. Data should be
considered suspectand verifiedas correct.A fresh
battery should be installed.
Note
: Battery monitoringis a useful technique only
when performed periodically. The M48T37Y/37V
only monitors the battery when a nominal V
CC
is
applied to the device. Thus applications which re-
quire extensive durations in the battery back-up
mode should be powered-up periodically (at least
once every few months) in orderfor this technique
to be beneficial. Additionally, if a battery low is in-
dicated, data integrity should be verified upon
power-up via a checksum or other technique.
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 13).
POWER SUPPLY DECOUPLING and
UNDERSHOOT PROTECTION
I
CC
transients, including those produced by output
switching, can produce voltage fluctuations, re-
sulting in spikes on the V
CC
bus. These transients
can be reduced if capacitors are used to store en-
ergy, 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 ceramic by-
pass capacitor value of 0.1
μ
F (as shown in Figure
13) is recommended in order to provide the need-
ed filtering.
In addition to transients that are caused by normal
SRAM operation, power cycling cangenerate neg-
ative voltage spikes on V
CC
that drive it to values
below V
SS
by as much as one Volt. These nega-
tive spikes can cause data corruptionin the SRAM
while in battery backup mode. To protect from
these voltage spikes, it is recommended to con-
nect 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 13. Supply Voltage Protection
AI02169
VCC
0.1
μ
F
DEVICE
VCC
VSS
Table 13. Default Values
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.
Condition
W
R
FT
AFE
ABE
WATCHDOG
Register
(1)
Initial Power-up
(Battery Attach for SNAPHAT)
(2)
0
0
0
0
0
0
Subsequent Power-up / RESET
(3)
0
0
0
0
0
0
Power-down
(4)
0
0
0
1
1
0
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| M48T37Y-70MH1 | 3.3V-5V 256 Kbit 32Kb x8 TIMEKEEPER SRAM |
| M48T37V-10MH1 | 3.3V-5V 256 Kbit 32Kb x8 TIMEKEEPER SRAM |
| M48T37Y-10MH1 | 3.3V-5V 256 Kbit 32Kb x8 TIMEKEEPER SRAM |
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相关代理商/技术参数 |
参数描述 |
|---|---|
| M48T37V-70MH1E | 制造商:STMICROELECTRONICS 制造商全称:STMicroelectronics 功能描述:3.3V-5V 256 Kbit 32Kb x8 TIMEKEEPER SRAM |
| M48T37V-70MH1F | 制造商:STMICROELECTRONICS 制造商全称:STMicroelectronics 功能描述:3.3V-5V 256 Kbit 32Kb x8 TIMEKEEPER SRAM |
| M48T37V-70MH1TR | 制造商:STMICROELECTRONICS 制造商全称:STMicroelectronics 功能描述:3.3V-5V 256 Kbit 32Kb x8 TIMEKEEPER SRAM |
| M48T37V-70MH6 | 制造商:STMICROELECTRONICS 制造商全称:STMicroelectronics 功能描述:3.3V-5V 256 Kbit 32Kb x8 TIMEKEEPER SRAM |
| M48T37V-70MH6E | 制造商:STMICROELECTRONICS 制造商全称:STMicroelectronics 功能描述:3.3V-5V 256 Kbit 32Kb x8 TIMEKEEPER SRAM |
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