BQ4802LYPW Datasheet, PDF (1/26 Pages) Texas Instruments – PARALLEL REAL-TIME CLOCK WITH CPU SUPERVISOR AND EXTERNAL SRAM NONVOLATILE MEMORY BACKUP

www.ti.com
bq4802Y
bq4802LY
SLUS464C – AUGUST 2000 – REVISED JUNE 2002
PARALLEL REAL-TIME CLOCK WITH CPU SUPERVISOR AND
EXTERNAL SRAM NONVOLATILE MEMORY BACKUP
FEATURES
D Real-Time Clock Counts Seconds Through
Centuries in BCD Format
– bq4802Y: 5-V Operation
– bq4802LY: 3.3-V Operation
D On-Chip Battery-Backup Switchover Circuit
With Nonvolatile Control for External SRAM
D Less Than 500 nA of Clock Operation Current
in Backup Mode
D Microprocessor Reset With Push-Button
Override
D Independent Watchdog Timer With
Programmable Time-Out Period
D Power-Fail Interrupt Warning
D Programmable Clock Alarm Interrupt Active
in Battery-Backup Mode
D Programmable Periodic Interrupt
D Battery-Low Warning
D 28-pin SOIC, TSSOP, and SNAPHAT Package
Options
TYPICAL APPLICATION
5 kΩ
APPLICATIONS
D Telecommunications Base Stations
D Servers
D Handheld Data Collection Equipment
D Medical Equipment
D Handheld Instrumentation
D Test Equipment
DESCRIPTION
The bq4802Y/bq4802LY real-time clock is a low-power
microprocessor peripheral that integrates a time-of-
day clock, a century-based calendar, and a CPU super-
visor, with package options including a 28-pin SOIC,
TSSOP, or SNAPHAT that requires the bq48SH-28x6
to complete the two-piece module. The bq4802Y/
bq4802LY is ideal for fax machines, copiers, industrial
control systems, point-of-sale terminals, data loggers,
and computers.
VCC
ADDRESS BUS
DATA BUS
FROM
ADDRESS
DECODE
LOGIC
FROM µP
I/O LINE
bq4802
A0–A3
DQ0–DQ7
RST
WDO
INT
CS
CEIN
VOUT
WDI
CEOUT
TO µP
ADDRESS BUS
DATA BUS
CMOS SRAM
62256L
A0–A3
DQ0–DQ7
VCC
CE
OE WR
BC
3V
LITHIUM
CELL
OE
WE
X1
X2
VSS
32.768 kHz
CRYSTAL
READ/
WRITE
CONTROL
FROM µP
Please be aware that an important notice concerning availability, standard warranty, and use in critical applications of Texas Instruments
semiconductor products and disclaimers thereto appears at the end of this data sheet.
PRODUCTION DATA information is current as of publication date. Products
conform to specifications per the terms of Texas Instruments standard warranty.
Production processing does not necessarily include testing of all parameters.
Copyright  2002, Texas Instruments Incorporated