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DS12R885_07 Datasheet, PDF (1/23 Pages) Maxim Integrated Products – RTC with Constant-Voltage Trickle Charger | |||
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Rev 5; 2/07
RTC with Constant-Voltage Trickle Charger
General Description
The DS12R885 is a functional drop-in replacement for
the DS12885 real-time clock (RTC). The device pro-
vides an RTC/calendar, one time-of-day alarm, three
maskable interrupts with a common interrupt output, a
programmable square wave, and 114 bytes of battery-
backed static RAM. The date at the end of the month is
automatically adjusted for months with fewer than 31
days, including correction for leap years. It also oper-
ates in either 24-hour or 12-hour format with an AM/PM
indicator. A precision temperature-compensated circuit
monitors the status of VCC. If a primary power failure is
detected, the device automatically switches to a back-
up supply. The VBACKUP pin supports a rechargeable
battery or a super cap and includes an integrated,
always enabled trickle charger. The DS12R885 is
accessed through a multiplexed byte-wide interface,
which supports both Intel and Motorola modes. The
DS12CR887 and DS12R887 integrate the DS12R885
die with a crystal and battery.
Applications
Embedded Systems
Utility Meters
Security Systems
Network Hubs, Bridges, and Routers
Features
⦠Trickle-Charge Capability for a Rechargeable
Battery or Super Cap
⦠Selectable Intel or Motorola Bus Timing
⦠RTC Counts Seconds, Minutes, Hours, Day, Date,
Month, and Year with Leap-Year Compensation to
2100
⦠Interrupt Output with Three Independently
Maskable Interrupt Flags
⦠Time-of-Day Alarm is Once-per-Second to Once-
per-Day
⦠Periodic Rates from 122μs to 500ms
⦠End-of-Clock Update Cycle Flag
⦠14 Bytes of Clock and Control Registers
⦠114 Bytes of General-Purpose Battery-Backed NV
RAM with Clear Input
⦠Programmable Square-Wave Output
⦠Automatic Power-Fail Detect and Switch Circuitry
⦠+5.0V or +3.3V Operation
⦠Industrial Temperature Range
⦠DS12CR887 Encapsulated DIP (EDIP) Module with
Integrated Battery and Crystal
⦠DS12R887 BGA Module Surface-Mountable
Package with Integrated Crystal and Rechargeable
Battery
Typical Operating Circuit
Ordering Information
DS83C520
CRYSTAL
VCC
X1 X2
AS
R/W
VCC
RESET
RCLR
DS
CS DS12R885
AD(0â7)
SQW
IRQ
VBACKUP
MOT
GND
SUPER
± CAP
PART
TEMP RANGE
PIN-
PACKAGE
TOP MARK*
DS12R885S-5
-40°C to +85°C 24 SO
DS12R885-5
(300 mils)
DS12R885S-5+
-40°C to +85°C
24 SO
(300 mils)
DS12R885-5
DS12R885S-5/
T&R
-40°C to +85°C
24 SO
(300 mils)
DS12R885-5
DS12R885S-5+
T&R
-40°C to +85°C
24 SO
(300 mils)
DS12R885-5
DS12R885S-33
-40°C to +85°C
24 SO
(300 mils)
DS12R885-33
+Denotes a lead-free/RoHS-compliant device.
T&R = Tape-and-reel.
*A â+â anywhere on the top mark indicates a lead-free device.
Ordering Information continued at end of data sheet.
Pin Configurations appear at end of data sheet.
______________________________________________ Maxim Integrated Products 1
For pricing, delivery, and ordering information, please contact Maxim/Dallas Direct! at
1-888-629-4642, or visit Maximâs website at www.maxim-ic.com.
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