参数资料
型号: BQ4285EPN
厂商: TEXAS INSTRUMENTS INC
元件分类: XO, clock
英文描述: 1 TIMER(S), REAL TIME CLOCK, PDIP24
封装: 0.600 INCH, PLASTIC, DIP-24
文件页数: 1/30页
文件大小: 1497K
代理商: BQ4285EPN
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
Selectable Intel or Motorola bus
timing (PLCC), Intel bus timing
(DIP and SOIC)
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
PN428502.eps
28-Pin PLCC
5
6
7
8
9
10
11
25
24
23
22
21
20
19
4
3
2
1
28
27
26
12
13
14
15
16
17
18
AD0
AD1
AD2
AD3
AD4
AD5
NC
AD
6
NC
AD
7
V
SS
CS
AS
NC
CEIN
BC
INT
RST
DS
VSS
R/ W
X2
X1
MOT
V
OUT
V
CC
SQW
CE
OUT
Pin Names
AD0–AD7
Multiplexed address/data
input/output
MOT
Bus type select input
(PLCC only )
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
Jan. 1999 B
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