DS12CR885 Datasheet, PDF (1/22 Pages) Maxim Integrated Products – RTC with Constant-Voltage Trickle Charger

Rev 1; 4/04
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 V_CC. If a primary power failure is
detected, the device automatically switches to a back-
up supply. The V_BACKUP 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
Typical Operating Circuit
CRYSTAL
V_CC
DS83C520
X1 X2
AS
V_CC
RESET
R/W
RCLR
DS
CS ^DS12R885
AD(0–7)
SQW
IRQ
V_BACKUP
MOT
GND
SUPER
± _CAP
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 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
Ordering Information
PART
TEMP RANGE
PIN-
PA CKA GE
TOP MARK
DS12R885-5
-40°C to +85°C
24 SO
(300 mils)
DS12R885-5
DS12R885-33
-40°C to +85°C
24 SO
(300 mils)
DS12R885-33
DS12CR887-5 -40°C to +85°C ^{24 EDIP} DS12CR887-5
(700 mils)
DS12CR887-33 -40°C to +85°C ^{24 EDIP} DS12CR887-33
(700 mils)
DS12R887-5* -40°C to +85°C 48 BGA DS12R887-5
DS12R887-33* -40°C to +85°C 48 BGA DS12R887-33
*Future product—contact factory for availability.
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 Maxim’s website at www.maxim-ic.com.