I2C Communications During Battery Backup and LVR " />
參數(shù)資料
型號: ISL12029IB30AZ
廠商: Intersil
文件頁數(shù): 18/29頁
文件大小: 0K
描述: IC RTC/CALENDAR EEPROM 14-SOIC
標準包裝: 1,000
類型: 時鐘/日歷
特點: 警報器,閏年,監(jiān)控器,監(jiān)視計時器
時間格式: HH:MM:SS(12/24 小時)
數(shù)據(jù)格式: YY-MM-DD-dd
接口: I²C,2 線串口
電源電壓: 2.7 V ~ 5.5 V
電壓 - 電源,電池: 1.8 V ~ 5.5 V
工作溫度: -40°C ~ 85°C
安裝類型: 表面貼裝
封裝/外殼: 14-SOIC(0.154",3.90mm 寬)
供應商設備封裝: 14-SOICN
包裝: 管件
25
FN6206.10
December 16, 2010
I2C Communications During Battery Backup and
LVR Operation
Operation in Battery Backup mode and LVR is affected by
the BSW and SBIB bits as described earlier. These bits allow
flexible operation of the serial bus and EEPROM in battery
backup mode, but certain operational details need to be
clear before utilizing the different modes. The most
significant detail is that once VDD goes below VRESET, then
I2C communications cease regardless of whether the device
is programmed for I2C operation in battery backup mode.
Table 11 describes 4 different modes possible with using the
BSW and SBIB bits, and how they are affect LVR and battery
backup operation.
Mode A - In this mode, selection bits indicate a low VDD
switchover combined with I2C operation in battery backup
mode. In actuality the VDD will go below VRESET before
switching to battery backup, which will disable I2C
ANYTIME the device goes into battery backup mode.
Regardless of the battery voltage, the I2C will work down
to the VRESET voltage (see Figure 29).
Mode B - In this mode, the selection bits indicate
switchover to battery backup at VDD<VBAT, and I
2C
communications in battery backup. In order to
communicate in battery backup mode, the VRESET voltage
must be less than the VBAT voltage AND VDD must be
greater than VRESET. Also, pull-ups on the I
2C bus pins
must go to VBAT to communicate. This mode is the same
as the normal operating mode of the X1228 device
Mode C - In this mode, the selection bits indicate a low
VDD switchover combined with no communications in
battery backup. Operation is actually identical to Mode A
with I2C communications down to VDD =VRESET, then no
communications (see Figure 29).
Mode D - In this mode, the selection bits indicate
switchover to battery backup at VDD<VBAT, and no I
2C
communications in battery backup. This mode is unique in
that there is I2C communication as long as VDD is higher
than VRESET or VBAT, whichever is greater. This mode is
the safest for guaranteeing I2C communications only when
there is a Valid VDD (see Figure 30).
TABLE 11. I2C, LV RESET, AND BATTERY BACKUP OPERATION SUMMARY (SHADED ROW IS SAME AS X1228 OPERATION)
MODE
SBIB
BIT
BSW
BIT
VBAT
SWITCHOVER
VOLTAGE
I2C ACTIVE IN
BATTERY
BACKUP?
EE PROM WRITE/
READ IN BATTERY
BACKUP?
FREQ/IRQ
ACTIVE?
NOTES
A
0
Standard Mode,
VTRIP = 2.2V typ
Default for
ISL12029A
NO
YES
Operation of I2C bus down to
VDD =VRESET, then below that no
communications. Battery switchover
at VTRIP.
B
(X1228
mode)
0
1
Legacy Mode,
VDD < VBAT
Default for
ISL12029
YES, only if
VBAT > VRESET
YES
Operation of I2C bus into battery
backup mode, but only for
VBAT > VDD > VRESET.
Bus must have pull-ups to VBAT. No
nonvolatile writes with VBAT>VDD
C
1
0
Standard Mode,
VTRIP = 2.2V typ
NO
YES
Operation of I2C bus down to
VDD =VRESET, then below that no
communications. Battery switchover
at VTRIP.
D
1
Legacy Mode,
VDD < VBAT
NO
YES
Operation of I2C bus down to VRESET
or VBAT, whichever is higher.
ISL12029, ISL12029A
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