- 您现在的位置：买卖IC网 > PDF目录378586 > DS12R885 (Maxim Integrated Products, Inc.) RTC with Constant-Voltage Trickle Charger PDF资料下载
参数资料
| 型号： | DS12R885 |
| 厂商： | Maxim Integrated Products, Inc. |
| 英文描述： | RTC with Constant-Voltage Trickle Charger |
| 中文描述： | 带有恒压涓流充电器的RTC |
| 文件页数： | 20/22页 |
| 文件大小： | 1093K |
| 代理商： | DS12R885 |
D
RTC with Constant-Voltage Trickle Charger
20
____________________________________________________________________
Update Cycle
The DS12R885 executes an update cycle once per
second regardless of the SET bit in Register B. When
the SET bit in Register B is set to 1, the user copy of the
double-buffered time, calendar, and alarm bytes is
frozen and does not update as the time increments.
However, the time countdown chain continues to
update the internal copy of the buffer. This feature
allows time to maintain accuracy independent of read-
ing or writing the time, calendar, and alarm buffers, and
also guarantees that time and calendar information is
consistent. The update cycle also compares each
alarm byte with the corresponding time byte and issues
an alarm if a match or if a don’t-care code is present in
all three positions.
There are three methods that can handle RTC access
that avoid any possibility of accessing inconsistent time
and calendar data. The first method uses the update-
ended interrupt. If enabled, an interrupt occurs after
every update cycle that indicates over 999ms is avail-
able to read valid time and date information. If this
interrupt is used, the IRQF bit in Register C should be
cleared before leaving the interrupt routine.
A second method uses the update-in-progress bit (UIP)
in Register A to determine if the update cycle is in
progress. The UIP bit pulses once per second. After
the UIP bit goes high, the update transfer occurs 244μs
later. If a low is read on the UIP bit, the user has at least
244μs before the time/calendar data is changed.
Therefore, the user should avoid interrupt service rou-
tines that would cause the time needed to read valid
time/calendar data to exceed 244μs.
The third method uses a periodic interrupt to determine
if an update cycle is in progress. The UIP bit in Register
A is set high between the setting of the PF bit in
Register C (
Figure
3). Periodic interrupts that occur at a
rate greater than t
BUC
allow valid time and date infor-
mation to be reached at each occurrence of the period-
ic interrupt. The reads should be complete within 1(t
PI/2
+ t
BUC
) to ensure that data is not read during the
update cycle.
SELECT BITS
REGISTER A
RS3
0
0
0
0
0
0
0
0
1
1
1
1
1
1
1
1
RS2
0
0
0
0
1
1
1
1
0
0
0
0
1
1
1
1
RS1
0
0
1
1
0
0
1
1
0
0
1
1
0
0
1
1
RS0
0
1
0
1
0
1
0
1
0
1
0
1
0
1
0
1
t
PI
PERIODIC
INTERRUPT
RATE
SQW OUTPUT
FREQUENCY
None
None
256Hz
128Hz
8.192kHz
4.096kHz
2.048kHz
1.024kHz
512Hz
256Hz
128Hz
64Hz
32Hz
16Hz
8Hz
4Hz
2Hz
3.90625ms
7.8125ms
122.070μs
244.141μs
488.281μs
976.5625μs
1.953125ms
3.90625ms
7.8125ms
15.625ms
31.25ms
62.5ms
125ms
250ms
500ms
Table
3. Periodic Interrupt Rate and
Square-Wave Output Frequency
UIP
UF
PF
t
BUC
= DELAY TIME BEFORE UPDATE
CYCLE = 244
μ
s
1 SECOND
tPI
t
P1/2
t
P1/2
t
BUC
Figure 3. UIP and Periodic Interrupt Timing
相关PDF资料 |
PDF描述 |
|---|---|
| DS12R885-33 | RTC with Constant-Voltage Trickle Charger |
| DS12R885-5 | RTC with Constant-Voltage Trickle Charger |
| DS12R887 | RTC with Constant-Voltage Trickle Charger |
| DS12R887-33 | RTC with Constant-Voltage Trickle Charger |
| DS12R887-5 | RTC with Constant-Voltage Trickle Charger |
相关代理商/技术参数 |
参数描述 |
|---|---|
| DS12R885-33 | 制造商:Maxim Integrated Products 功能描述:REAL TIME CLOCK MULTIPLEXED 114BYTE - Bulk |
| DS12R885-5 | 制造商:Maxim Integrated Products 功能描述:REAL TIME CLOCK MULTIPLEXED 114BYTE - Bulk |
| DS12R885S-33 | 制造商:Rochester Electronics LLC 功能描述: 制造商:Maxim Integrated Products 功能描述: |
| DS12R885S-33/T&R | 制造商:Maxim Integrated Products 功能描述:REAL TIME CLOCK MULTIPLEXED 114BYTE 24SOIC W - Tape and Reel |
| DS12R885S-33+ | 功能描述:实时时钟 RTC w/Constant V Trickle Charger RoHS:否 制造商:Microchip Technology 功能:Clock, Calendar. Alarm RTC 总线接口:I2C 日期格式:DW:DM:M:Y 时间格式:HH:MM:SS RTC 存储容量:64 B 电源电压-最大:5.5 V 电源电压-最小:1.8 V 最大工作温度:+ 85 C 最小工作温度: 安装风格:Through Hole 封装 / 箱体:PDIP-8 封装:Tube |
发布紧急采购，3分钟左右您将得到回复。