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參數(shù)資料
| 型號： | BQ4285Q |
| 廠商： | TEXAS INSTRUMENTS INC |
| 元件分類： | XO, clock |
| 英文描述： | 1 TIMER(S), REAL TIME CLOCK, PQCC28 |
| 封裝： | PLASTIC, LCC-28 |
| 文件頁數(shù)： | 23/26頁 |
| 文件大?。?/td> | 1079K |
| 代理商： | BQ4285Q |
Square-Wave Output
The bq4285 divides the 32.768kHz oscillator frequency
to produce the 1 Hz update frequency for the clock and
calendar. Thirteen taps from the frequency divider are
fed to a 16:1 multiplexer circuit. The output of this mux
is fed to the SQW output and periodic interrupt genera-
tion circuitry. The four least-significant bits of register
A, RS0–RS3, select among the 13 taps (see Table 3). The
square-wave output is enabled by writinga1tothe
square-wave enable bit (SQWE) in register B.
Interrupts
The bq4285 allows three individually selected interrupt
events to generate an interrupt request. These three in-
terrupt events are:
s
The periodic interrupt, programmable to occur once
every 122
s to 500 ms
s
The alarm interrupt, programmable to occur once per
second to once per day
s
The update-ended interrupt, which occurs at the end
of each update cycle
Each of the three interrupt events is enabled by an indi-
vidual interrupt-enable bit in register B. When an event
occurs, its event flag bit in register C is set. If the corre-
sponding event enable bit is also set, then an interrupt
request is generated.
The interrupt request flag bit
(INTF) of register C is set with every interrupt request.
Reading register C clears all flag bits, including INTF,
and makes INT high-impedance.
Two methods can be used to process bq4285 interrupt
events:
s
Enable interrupt events and use the interrupt
request output to invoke an interrupt service routine.
s
Do not enable the interrupts and use a polling
routine to periodically check the status of the flag
bits.
The individual interrupt sources are described in detail
in the following sections.
6
Register A Bits
Square Wave
Periodic Interrupt
RS3
RS2
RS1
RS0
Frequency
Units
Period
Units
0000
None
0001
256
Hz
3.90625
ms
0010
128
Hz
7.8125
ms
0011
8.192
kHz
122.070
s
0100
4.096
kHz
244.141
s
0101
2.048
kHz
488.281
s
0110
1.024
kHz
976.5625
s
0111
512
Hz
1.95315
ms
1000
256
Hz
3.90625
ms
1001
128
Hz
7.8125
ms
1010
64
Hz
15.625
ms
1011
32
Hz
31.25
ms
1100
16
Hz
62.5
ms
11018
Hz
125
ms
11104
Hz
250
ms
11112
Hz
500
ms
Table 3. Square-Wave Frequency/Periodic Interrupt Rate
Jan. 1999 D
bq4285
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相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| BQ4285Q- | 制造商:TI 制造商全稱:Texas Instruments 功能描述:Real-Time Clock RTC With NVRAM Control |
| BQ4285S- | 制造商:TI 制造商全稱:Texas Instruments 功能描述:Real-Time Clock RTC With NVRAM Control |
| BQ4285S-SB2 | 功能描述:實時時鐘 RTC IC: 114x8 NVSRAM & NVSRAM Control RoHS:否 制造商:Microchip Technology 功能:Clock, Calendar. Alarm RTC 總線接口:I2C 日期格式:DW:DM:M:Y 時間格式:HH:MM:SS RTC 存儲容量:64 B 電源電壓-最大:5.5 V 電源電壓-最小:1.8 V 最大工作溫度:+ 85 C 最小工作溫度: 安裝風格:Through Hole 封裝 / 箱體:PDIP-8 封裝:Tube |
| BQ4285S-SB2G4 | 功能描述:實時時鐘 RTC IC: 114x8 NVSRAM & NVSRAM Control RoHS:否 制造商:Microchip Technology 功能:Clock, Calendar. Alarm RTC 總線接口:I2C 日期格式:DW:DM:M:Y 時間格式:HH:MM:SS RTC 存儲容量:64 B 電源電壓-最大:5.5 V 電源電壓-最小:1.8 V 最大工作溫度:+ 85 C 最小工作溫度: 安裝風格:Through Hole 封裝 / 箱體:PDIP-8 封裝:Tube |
| BQ4285S-SB2TR | 功能描述:實時時鐘 RTC IC: 114x8 NVSRAM & NVSRAM Control RoHS:否 制造商:Microchip Technology 功能:Clock, Calendar. Alarm RTC 總線接口:I2C 日期格式:DW:DM:M:Y 時間格式:HH:MM:SS RTC 存儲容量:64 B 電源電壓-最大:5.5 V 電源電壓-最小:1.8 V 最大工作溫度:+ 85 C 最小工作溫度: 安裝風格:Through Hole 封裝 / 箱體:PDIP-8 封裝:Tube |
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