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参数资料
| 型号： | M48T02-200PC1 |
| 厂商： | STMICROELECTRONICS |
| 元件分类： | 时钟/数据恢复及定时提取 |
| 英文描述： | 0 TIMER(S), REAL TIME CLOCK, PDIP24 |
| 封装： | 0.600 INCH, ROHS COMPLIANT, PLASTIC, DIP-24 |
| 文件页数： | 5/25页 |
| 文件大小： | 199K |
| 代理商： | M48T02-200PC1 |
M48T02, M48T12
Clock operations
Table 5.
Register map
Keys:
S = SIGN bit
FT = FREQUENCY TEST bit (set to '0' for normal clock operation)
R = READ bit
W = WRITE bit
ST = STOP bit
0 = Must be set to '0'
3.3
Stopping and starting the oscillator
The oscillator may be stopped at any time. If the device is going to spend a significant
amount of time on the shelf, the oscillator can be turned off to minimize current drain on the
battery. The STOP bit is the MSB of the seconds register. Setting it to a '1' stops the
oscillator. The M48T02/12 is shipped from STMicroelectronics with the STOP bit set to a '1.'
When reset to a '0,' the M48T02/12 oscillator starts within one second.
3.4
Calibrating the clock
The M48T02/12 is driven by a quartz-controlled oscillator with a nominal frequency of
32,768 Hz. A typical M48T02/12 is accurate within 1 minute per month at 25°C without
calibration. The devices are tested not to exceed ± 35 ppm (parts per million) oscillator
frequency error at 25°C, which equates to about ±1.53 minutes per month.
The oscillation rate of any crystal changes with temperature. Figure 8 on page 15 shows the
frequency error that can be expected at various temperatures. Most clock chips compensate
for crystal frequency and temperature shift error with cumbersome “trim” capacitors. The
M48T02/12 design, however, employs periodic counter correction. The calibration circuit
adds or subtracts counts from the oscillator divider circuit at the divide by 256 stage, as
shown in Figure 9 on page 15. The number of times pulses are blanked (subtracted,
negative calibration) or split (added, positive calibration) depends upon the value loaded into
the five-bit calibration byte found in the control register. Adding counts speeds the clock up,
subtracting counts slows the clock down.
The calibration byte occupies the five lower order bits in the control register. This byte can
be set to represent any value between 0 and 31 in binary form. The sixth bit is the sign bit;
Address
Data
Function/range
BCD format
D7
D6
D5
D4
D3
D2
D1
D0
7FF
10 years
Year
00-99
7FE
0
10 M
Month
01-12
7FD
0
10 date
Date
01-31
7FC
0
FT
0
Day
01-07
7FB
0
10 hours
Hours
00-23
7FA
0
10 minutes
Minutes
00-59
7F9
ST
10 seconds
Seconds
00-59
7F8
W
R
S
Calibration
Control
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相关代理商/技术参数 |
参数描述 |
|---|---|
| M48T02-200PC1 | 制造商:STMicroelectronics 功能描述:IC SRAM TIMEKEEPER 16K |
| M48T02-200PC1TR | 制造商:STMICROELECTRONICS 制造商全称:STMicroelectronics 功能描述:5.0V, 16 Kbit (2Kb x 8) TIMEKEEPER㈢ SRAM |
| M48T02-70PC1 | 功能描述:实时时钟 16K (2Kx8) 70ns 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 |
| M48T02-70PC1 | 制造商:STMicroelectronics 功能描述:IC NVRAM 10 YR BATTERY 16K 48T02 |
| M48T02-70PC1TR | 制造商:STMICROELECTRONICS 制造商全称:STMicroelectronics 功能描述:5.0V, 16 Kbit (2Kb x 8) TIMEKEEPER㈢ SRAM |
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