DS12CR887

Manufacturer Part NumberDS12CR887
DescriptionThe DS12R885 is a functional drop-in replacement for the DS12885 real-time clock (RTC)
ManufacturerMaxim
DS12CR887 datasheet
 


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19-5217; Rev 6; 4/10
RTCs 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
. If a primary power failure is
CC
detected, the device automatically switches to a back-
up supply. The V
pin supports a rechargeable
BACKUP
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
X1
X2
AS
R/W
DS
DS83C520
DS12R885
CS
AD(0–7)
IRQ
MOT
GND
Pin Configurations appear at end of data sheet.
For pricing, delivery, and ordering information, please contact Maxim Direct at 1-888-629-4642,
or visit Maxim’s website at www.maxim-ic.com.
♦ 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
PART
V
CC
DS12R885S-5+
V
CC
DS12R885S-5+
RESET
T&R
RCLR
DS12R885S-33+ -40°C to +85°C
DS12R885S-33+
SQW
T&R
V
BACKUP
DS12CR887-5+ -40°C to +85°C
SUPER
±
CAP
DS12CR887-33+ -40°C to +85°C
DS12R887-5
DS12R887-33
+ Denotes a lead(Pb)-free/RoHS-compliant package.
T&R = Tape and reel.
* A “+” anywhere on the top mark indicates a lead(Pb)-free
device.
______________________________________________ Maxim Integrated Products
Features
Ordering Information
PIN-
TEMP RANGE
TOP MARK*
PACKAGE
24 SO
-40°C to +85°C
DS12R885-5
(300 mils)
24 SO
-40°C to +85°C
DS12R885-5
(300 mils)
24 SO
DS12R885-33
(300 mils)
24 SO
-40°C to +85°C
DS12R885-33
(300 mils)
24 EDIP
DS12CR887-5
(700 mils)
24 EDIP
DS12CR887-33
(700 mils)
-40°C to +85°C 48 BGA
DS12R887-5
-40°C to +85°C 48 BGA
DS12R887-33
1

DS12CR887 Summary of contents

  • Page 1

    ... 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 ...

  • Page 2

    ... SO ...................................................................-55°C to +125°C Stresses beyond those listed under “Absolute Maximum Ratings” may cause permanent damage to the device. These are stress ratings only, and functional operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to absolute maximum rating conditions for extended periods may affect device reliability ...

  • Page 3

    RTCs with Constant-Voltage Trickle Charger DC ELECTRICAL CHARACTERISTICS (DS12R885 Only 0V 3.2V -40°C to +85°C, unless otherwise noted.) (Note 1) CC BACKUP A PARAMETER SYMBOL V Current (OSC On); BACKUP I BACKUP2 T = ...

  • Page 4

    RTCs with Constant-Voltage Trickle Charger AC ELECTRICAL CHARACTERISTICS (V = 2.97V to 3.63V -40°C to +85°C.) (Note PARAMETER SYMBOL Cycle Time Pulse Width, DS Low or R/W High Pulse Width, DS High or R/W Low ...

  • Page 5

    RTCs with Constant-Voltage Trickle Charger ASD AD0–AD7 WRITE AD0–AD7 READ AS PW ASH t ASD DS t ASD R ASL AD0–AD7 WRITE _____________________________________________________________________ Motorola Bus Read/Write Timing ASH t ...

  • Page 6

    RTCs with Constant-Voltage Trickle Charger AS t ASD DS t ASD R/W CS AD0–AD7 IRQ Release Delay Timing DS RESET IRQ t IRDS PF(MAX) V PF(MIN) RECOGNIZED INPUTS OUTPUTS 6 _____________________________________________________________________ t CYC PW ASH t ASED ...

  • Page 7

    ... SYMBOL Recovery at Power-Up V Fall Time PF(MAX) V PF(MIN) V Rise Time PF(MIN) V PF(MAX) DATA RETENTION (DS12CR887) PARAMETER SYMBOL Expected Data Retention CAPACITANCE (T = +25°C) A PARAMETER SYMBOL Capacitance on All Input Pins Except X1 and X2 Capacitance on IRQ, SQW, and DQ Pins AC TEST CONDITIONS PARAMETER Input Pulse Levels (-5) ...

  • Page 8

    RTCs with Constant-Voltage Trickle Charger (V = +3.3V +25°C, unless otherwise noted BACKUP (DS12R885) 625 600 575 550 2.0 2.3 V BACKUP I vs. TEMPERATURE BACKUP (DS12R885) 650 V = 0V, CC 625 V = ...

  • Page 9

    ... RTCs with Constant-Voltage Trickle Charger X1 X2 DS12R887/ V DS12CR887 CC ONLY V BACKUP CONTROL CHARGER GND DS12R887/ DS12CR887 CS ONLY R INTERFACE MOT RESET AD0–AD7 RLCR PIN NAME SO EDIP BGA MOT 2 — — — — X2 F4, D4, F3, D3, AD0– 4–11 4–11 F2, D2, ...

  • Page 10

    RTCs with Constant-Voltage Trickle Charger PIN NAME SO EDIP BGA D5–D8, 12 E1–E8, GND F5– N.C. 20– ...

  • Page 11

    ... G. Interrupt-request status flag (IRQF) bit is cleared IRQ pin is in the high-impedance state. I. The device is not accessible until RESET is returned high. J. Square-wave output-enable (SQWE) bit is cleared greater than the DS12CR887 and DS12R887, the V CC BACKUP is not applied. The RCLR function is designed to be used through a human CC ...

  • Page 12

    ... The device is accessed through a multiplexed byte-wide interface, which supports both Intel and Motorola modes. The DS12CR887 EDIP integrates a DS12R885 die with a crystal and battery. The charging circuit on the DS12R885 die is disabled. The battery has sufficient capacity to power the oscillator and registers for five years in the absence +25° ...

  • Page 13

    ... Refer to Application Note 58: Crystal Considerations with Dallas Real-Time Clocks (RTCs) for more detailed information. The DS12R887 and DS12CR887 are calibrated at the factory to an accuracy of ±1 minute per month at +25°C during data-retention time for the period t ...

  • Page 14

    RTCs with Constant-Voltage Trickle Charger methods of avoiding any possible incorrect time and calendar reads are covered later in this text. The three alarm bytes can be used in two ways. First, when the alarm time is written in the ...

  • Page 15

    RTCs with Constant-Voltage Trickle Charger Table 2B. Time, Calendar, and Alarm Data Modes—Binary Mode ( ADDRESS BIT 7 BIT 6 BIT 5 00H 0 0 01H 0 0 02H 0 0 03H 0 0 AM/PM 04H 0 0 ...

  • Page 16

    RTCs with Constant-Voltage Trickle Charger Control Registers The DS12R885 has four control registers that are accessible at all times, even during the update cycle. BIT 7 BIT 6 BIT 5 UIP DV2 Bit 7: Update-In-Progress (UIP). This bit is a ...

  • Page 17

    RTCs with Constant-Voltage Trickle Charger BIT 7 BIT 6 BIT 5 SET PIE Bit 7: SET. When the SET bit is 0, the update transfer functions normally by advancing the counts once per second. When the SET bit is written ...

  • Page 18

    RTCs with Constant-Voltage Trickle Charger BIT 7 BIT 6 BIT 5 IRQF PF Bit 7: Interrupt Request Flag (IRQF). This bit is set to 1 when any of the following are true PIE = AIE ...

  • Page 19

    ... DS12R885. The act of reading Register C clears all active flag bits and the IRQF bit. When the DS12R887 and DS12CR887 are shipped from the factory, the internal oscillator is turned off. This feature prevents the lithium energy cell from being used until it is installed in a system ...

  • Page 20

    RTCs with Constant-Voltage Trickle Charger Table 3. Periodic Interrupt Rate and Square-Wave Output Frequency SELECT BITS t PERIODIC PI REGISTER A INTERRUPT RATE RS3 RS2 RS1 RS0 None 3.90625ms ...

  • Page 21

    ... Refer to the IPC/JEDEC J-STD-020B standard for Moisture-Sensitive Device (MSD) classifications. The EDIP (DS12CR887) module can be successfully processed through conventional wave-soldering tech- niques so long as temperature exposure to the lithium energy source does not exceed +85°C. Post-solder cleaning with water-washing techniques is acceptable, provided that ultrasonic vibration is not used ...

  • Page 22

    ... For the latest package outline information and land patterns, AD3 GND AD2 go to www.maxim-ic.com/packages. Note that a “+”, “#”, or “-” in the package code indicates RoHS status only. Package AD1 GND AD0 drawings may show a different suffix character, but the drawing pertains to the package regardless of RoHS status ...

  • Page 23

    ... Intel Bus Read Timing diagram; added a note about how the missing 5 2/07 V pin on the DS12CR887 and DS12R887 is internally connected to a lithium BACKUP cell; added the Package Information table. Updated the storage temperature ranges, added the lead temperature, and updated the ...