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參數(shù)資料
| 型號(hào)： | BQ4285Q |
| 廠商： | TEXAS INSTRUMENTS INC |
| 元件分類(lèi)： | XO, clock |
| 英文描述： | 1 TIMER(S), REAL TIME CLOCK, PQCC28 |
| 封裝： | PLASTIC, LCC-28 |
| 文件頁(yè)數(shù)： | 20/26頁(yè) |
| 文件大小： | 1079K |
| 代理商： | BQ4285Q |
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AS
Address strobe input
AS serves to demultiplex the address/data
bus. The falling edge of AS latches the ad-
dress on AD0–AD7.
This demultiplexing
process is independent of the CS signal.
For DIP, SOIC, and PLCC packages with
MOT=VCC, the AS input is provided a sig-
nal similar to ALE in an Intel-based sys-
tem.
DS
Data strobe input
For DIP, SOIC, and PLCC packages with
MOT=VSS, the DS input is provided a sig-
nal similar to RD, MEMR, or I/OR in an
Intel-based system. The falling edge on DS
is used to enable the outputs during a read
cycle.
For the PLCC package, when MOT = VCC,
DS controls data transfer during a bq4285
bus cycle. During a read cycle, the bq4285
drives the bus after the rising edge on DS.
During a write cycle, the falling edge on DS
is used to latch write data into the chip.
R/W
Read/write input
For DIP, SOIC, and PLCC packages with
MOT=VSS, R/W is provided a signal simi-
lar to WR, MEMW, or I/OW in an Intel-
based system.
The rising edge on R/W
latches data into the bq4285.
For the PLCC package, when MOT = VCC,
the level on R/W identifies the direction of
data transfer.
A high level on R/W indi-
cates a read bus cycle, whereas a low on
this pin indicates a write bus cycle.
INT
Interrupt request output
INT is an open-drain output.
INT is as-
serted low when any event flag is set and
the corresponding event enable bit is also
set.
INT
becomes
high-impedance
whenever register C is read (see the Con-
trol/Status Registers section).
RST
Reset input
The bq4285 is reset when RST is pulled
low.
When reset, INT becomes high-
impedance, and the bq4285 is not accessi-
ble. Table 4 in the Control/Status Registers
section lists the register bits that are
cleared by a reset.
Reset may be disabled by connecting RST
to VCC. This allows the control bits to re-
tain
their
states
through
power-
down/power-up cycles.
SQW
Square-wave output
SQW may output a programmable fre-
quency square-wave signal during normal
(VCC valid) system operation. Any one of
the 13 specific frequencies may be selected
through register A.
This pin is held low
when the square-wave enable bit (SQWE)
in register B is 0 (see the Control/Status
Registers section).
BC
3V backup cell input
BC should be connected to a 3V backup cell
for RTC operation and storage register non-
volatility in the absence of power.
When
VCC slews down past VBC (3V typical), the
integral
control
circuitry
switches
the
power source to BC.
When VCC returns
above VBC, the power source is switched to
VCC.
Upon power-up, a voltage within the VBC
range must be present on the BC pin for
the oscillator to start up.
X1–X2
Crystal inputs
The X1–X2 inputs are provided for an ex-
ternal 32.768Khz quartz crystal, Daiwa
DT-26 or equivalent, with 6pF load capaci-
tance. A trimming capacitor may be neces-
sary for extremely precise time-base gen-
eration.
CEIN
External RAM chip enable input,
active low
CEIN should be driven low to enable the
controlled external RAM. CEIN is internally
pulled up with a 50K
resistor.
CEOUT
External RAM chip enable output,
active low
When power is valid, CEOUT reflects CEIN.
VOUT
Supply output
VOUT provides the higher of VCC or VBC,
switched internally, to supply external RAM.
VCC
+5V supply
VSS
Ground
3
Jan. 1999 D
bq4285
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| BQ4285S-SB2 | 功能描述:實(shí)時(shí)時(shí)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(shí)間格式:HH:MM:SS RTC 存儲(chǔ)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(fēng)格:Through Hole 封裝 / 箱體:PDIP-8 封裝:Tube |
| BQ4285S-SB2G4 | 功能描述:實(shí)時(shí)時(shí)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(shí)間格式:HH:MM:SS RTC 存儲(chǔ)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(fēng)格:Through Hole 封裝 / 箱體:PDIP-8 封裝:Tube |
| BQ4285S-SB2TR | 功能描述:實(shí)時(shí)時(shí)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(shí)間格式:HH:MM:SS RTC 存儲(chǔ)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(fēng)格:Through Hole 封裝 / 箱體:PDIP-8 封裝:Tube |
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