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Features
Direct clock/calendar replace-
ment for IBM
AT-compatible
computers and other applications
114 bytes of general nonvolatile
storage
Enhanced features include:
- System wake-up capability—
alarm interrupt output active
in battery-backup mode
- 2.7–3.6V operation (bq4285L);
4.5–5.5V operation (bq4285E)
- 32kHz output for power
management
Automatic backup and write-
protect control to external SRAM
Functionally compatible with the
DS1285
Less than 0.5
A load under bat-
tery operation
14 bytes for clock/calendar and
control
BCD or binary format for clock
and calendar data
Calendar in day of the week, day
of the month, months, and years,
with automatic leap-year adjust-
ment
Time of day in seconds, minutes,
and hours
- 12- or 24-hour format
- Optional daylight saving
adjustment
Programmable square wave out-
put
Three individually maskable in-
terrupt event flags:
- Periodic rates from 122s to
500ms
- Time-of-day alarm once per
second to once per day
- End-of-clock update cycle
24-pin plastic DIP or SOIC
General Description
The CMOS bq4285E/L is a low-power
microprocessor peripheral providing a
time-of-day clock and 100-year calen-
dar with alarm features and battery
operation. Other features include
three maskable interrupt sources,
square wave output, and 114 bytes of
general nonvolatile storage.
A 32.768kHz output is available for
sustaining power-management activi-
ties. Wake-up capability is provided by
an alarm interrupt, which is active in
battery-backup mode.
The bq4285E/L write-protects the
clock, calendar, and storage registers
during power failure. A backup bat-
tery then maintains data and oper-
ates the clock and calendar.
The bq4285E/L is a fully compatible
real-time clock for IBM AT-
compatible computers and other ap-
plications. The only external compo-
nents are a 32.768kHz crystal and a
backup battery.
The
bq4285E/L
integrates
a
battery-backup controller to make a
1
28-Pin PLCC: No Longer Available
Pin Names
AD0–AD7
Multiplexed address/data
input/output
MOT
Bus type select input
CS
Chip select input
AS
Address strobe input
DS
Data strobe input
R/W
Read/write input
INT
Interrupt request output
RST
Reset input
SQW
Square wave output
BC
3V backup cell input
X1–X2
Crystal inputs
NC
No connect
CEIN
RAM chip enable input
CEOUT
RAM chip enable output
VOUT
Supply output
VCC
+5V supply
bq4285E/L
1
PN428501.eps
24-Pin DIP or SOIC
2
3
4
5
6
7
8
24
23
22
21
20
19
18
17
9
10
16
15
11
12
14
13
VCC
SQW
CEOUT
BC
INT
RST
DS
VSS
R/W
AS
CS
VOUT
X1
X2
AD0
AD1
AD2
AD3
AD4
AD5
AD6
AD7
VSS
CEIN
Pin Connections
Enhanced RTC With NVRAM Control
SLUS006A - MAY 1994 - REVISED MAY 2004
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相关代理商/技术参数
BQ4285ES
制造商:未知厂家 制造商全称:未知厂家 功能描述:
BQ4285L
制造商:未知厂家 制造商全称:未知厂家 功能描述:Enhanced RTC With NVRAM Control
BQ4285LP
制造商:TI 制造商全称:Texas Instruments 功能描述:Enhanced RTC With NVRAM Control
BQ4285LQ
制造商:未知厂家 制造商全称:未知厂家 功能描述:
BQ4285LS
制造商:Rochester Electronics LLC 功能描述:- Bulk
BQ4285LSTR
制造商:TI 制造商全称:Texas Instruments 功能描述:Enhanced RTC With NVRAM Control
BQ4285P-
制造商:TI 制造商全称:Texas Instruments 功能描述:Real-Time Clock RTC With NVRAM Control
BQ4285P-SB2
功能描述:实时时钟 RTC IC: 114x8 NVSRAM & NVSRAM Control 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