Datasheet

ManualsBrandsMAXIM INTEGRATED ManualsIntegrated Circuits (ICs)Timer IC t- real time clock Clock/calendar SOIC 24 W

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

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

Features

o Trickle-Charge Capability for a Rechargeable

Battery or Super Cap

o Selectable Intel or Motorola Bus Timing

o RTC Counts Seconds, Minutes, Hours, Day, Date,

Month, and Year with Leap-Year Compensation to

2100

o Interrupt Output with Three Independently

Maskable Interrupt Flags

o Time-of-Day Alarm is Once-per-Second to Once-

per-Day

o Periodic Rates from 122µs to 500ms

o End-of-Clock Update Cycle Flag

o 14 Bytes of Clock and Control Registers

o 114 Bytes of General-Purpose Battery-Backed NV

RAM with Clear Input

o Programmable Square-Wave Output

o Automatic Power-Fail Detect and Switch Circuitry

o +5.0V or +3.3V Operation

o Industrial Temperature Range

o DS12CR887 Encapsulated DIP (EDIP) Module with

Integrated Battery and Crystal

o DS12R887 BGA Module Surface-Mountable

Package with Integrated Crystal and

Rechargeable Battery

19-5217; Rev 7; 9/13

DS12R885/DS12CR887/

DS12R887

RTCs with Constant-Voltage Trickle Charger

For pricing, delivery, and ordering information, please contact Maxim Direct

at 1-888-629-4642, or visit Maxim’s website at www.maximintegrated.com.

DS12R885

DS83C520

R/W

GND

X2X1

CRYSTAL

BACKUP

SUPER

CAP

AD(0–7) SQW

RESET

IRQ

RCLR

MOT

Typical Operating Circuit

PART TEMP RANGE

PIN-

PACKAGE

TOP MARK*

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-33+ -40°C to +85°C

24 SO

(300 mils)

DS12R885-33

DS12R885S-33+

T&R

-40°C to +85°C

24 SO

(300 mils)

DS12R885-33

DS12CR887-5+ -40°C to +85°C

24 EDIP

(700 mils)

DS12CR887-5

DS12CR887-33+ -40°C to +85°C

24 EDIP

(700 mils)

DS12CR887-33

DS12R887-5 -40°C to +85°C 48 BGA DS12R887-5

DS12R887-33 -40°C to +85°C 48 BGA DS12R887-33

Pin Configurations appear at end of data sheet.

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.

Ordering Information

Summary of content (23 pages)

PAGE 1
DS12R885/DS12CR887/ DS12R887 RTCs with Constant-Voltage Trickle Charger General Description Features The DS12R885 is a functional drop-in replacement for the DS12885 real-time clock (RTC). The device provides an RTC/calendar, one time-of-day alarm, three maskable interrupts with a common interrupt output, a programmable square wave, and 114 bytes of batterybacked 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.
PAGE 2
DS12R885/DS12CR887/DS12R887 RTCs with Constant-Voltage Trickle Charger ABSOLUTE MAXIMUM RATINGS Voltage Range on VCC Pin Relative to Ground .....-0.3V to +6.0V Operating Temperature Range ...........................-40°C to +85°C Storage Temperature Range EDIP, BGA ........................................................-40°C to +85°C SO ...................................................................-55°C to +125°C Lead Temperature (soldering, 10s) .................................
PAGE 3
DS12R885/DS12CR887/DS12R887 RTCs with Constant-Voltage Trickle Charger DC ELECTRICAL CHARACTERISTICS (DS12R885 Only) (VCC = 0V, VBACKUP = 3.2V, TA = -40°C to +85°C, unless otherwise noted.) (Note 1) PARAMETER VBACKUP Current (OSC On); TA = +25°C, VBACKUP = 3.0V VBACKUP Current (Oscillator Off) SYMBOL IBACKUP2 CONDITIONS MIN (Note 7) TYP MAX UNITS 800 1000 nA 100 nA MAX UNITS DC ns IBACKUPDR (Note 7) AC ELECTRICAL CHARACTERISTICS (VCC = 4.5V to 5.5V, TA = -40°C to +85°C.
PAGE 4
DS12R885/DS12CR887/DS12R887 RTCs with Constant-Voltage Trickle Charger AC ELECTRICAL CHARACTERISTICS (VCC = 2.97V to 3.63V, TA = -40°C to +85°C.
PAGE 5
DS12R885/DS12CR887/DS12R887 RTCs with Constant-Voltage Trickle Charger Motorola Bus Read/Write Timing PWASH tASED AS tASD tCYC PWEH PWEL DS tRWS tRWH R/ W tCH tCS CS tDSW tDHW AD0–AD7 WRITE tAHL tASL tDHR AD0–AD7 READ tDDR Intel Bus Write Timing tCYC AS PWASH tASD DS tASED tASD R/W PWEH PWEL tCH tCS CS tASL tAHL tDSW tDHW AD0–AD7 WRITE Maxim Integrated 5
PAGE 6
DS12R885/DS12CR887/DS12R887 RTCs with Constant-Voltage Trickle Charger Intel Bus Read Timing tCYC PWASH AS tASD tASED DS PWEH PWEL tASD R/W tCH tCS CS tASL tDHR tDDR tAHL AD0–AD7 IRQ Release Delay Timing DS RESET tRWL IRQ tIRR tIRDS Power-Up/Power-Down Timing VCC VPF(MAX) VPF(MIN) tF tR tRPU tDR INPUTS RECOGNIZED DON'T CARE RECOGNIZED HIGH-Z OUTPUTS 6 VALID VALID Maxim Integrated
PAGE 7
DS12R885/DS12CR887/DS12R887 RTCs with Constant-Voltage Trickle Charger POWER-UP/POWER-DOWN CHARACTERISTICS (TA = -40°C to +85°C) (Note 1) PARAMETER SYMBOL Recovery at Power-Up CONDITIONS MIN TYP MAX UNITS 200 ms tRPU 20 VCC Fall Time; VPF(MAX) to VPF(MIN) tF 300 µs VCC Rise Time; VPF(MIN) to VPF(MAX) tR 0 µs DATA RETENTION (DS12CR887) PARAMETER SYMBOL Expected Data Retention tDR CONDITIONS TA = +25°C MIN TYP MAX 5 UNITS Years CAPACITANCE (TA = +25°C) PARAMETER SYMBOL Capacita
PAGE 8
DS12R885/DS12CR887/DS12R887 RTCs with Constant-Voltage Trickle Charger Typical Operating Characteristics (VCC = +3.3V, TA = +25°C, unless otherwise noted.) IBACKUP vs. VBACKUP (DS12R885) VBACKUP vs. VCC vs. IBACKUP (DS12R885) DS12R885 toc02 3.0 0μA -15μA 2.8 600 VBACKUP (V) SUPPLY CURRENT (nA) VCC = 0V DS12R885 toc01 625 -30μA 2.6 -45μA 2.4 575 -60μA 2.2 550 2.0 2.3 2.5 2.8 3.0 VCC (V) IBACKUP vs. TEMPERATURE (DS12R885) OSCILLATOR FREQUENCY vs. SUPPLY VOLTAGE 32768.08 32768.
PAGE 9
DS12R885/DS12CR887/DS12R887 RTCs with Constant-Voltage Trickle Charger Functional Diagram X1 OSC DIVIDE BY 8 DIVIDE BY 64 DIVIDE BY 64 X2 DS12R887/ DS12CR887 ONLY VCC GND DS12R887/ DS12CR887 ONLY 16:1 MUX POWER CONTROL AND TRICKLE CHARGER VBACKUP DS12R885 SQUAREWAVE GENERATOR SQW IRQ GENERATOR IRQ CS R/W REGISTERS A, B, C, D DS BUS INTERFACE AS MOT RESET CLOCK/CALENDAR UPDATE LOGIC CLOCK/CALENDAR AND ALARM REGISTERS BUFFERED CLOCK/ CALENDAR AND ALARM REGISTERS AD0–AD7 USER RAM 114 BYTE
PAGE 10
DS12R885/DS12CR887/DS12R887 RTCs with Constant-Voltage Trickle Charger Pin Description (continued) SO PIN EDIP 12, 16 12 13 14 14 D5–D8, E1–E8, F5–F8 C1 C3 NAME GND FUNCTION Ground CS Chip-Select Input. The active-low chip-select signal must be asserted low for a bus cycle in the DS12R885 to be accessed. CS must be kept in the active state during DS and AS for Motorola timing and during DS and R/W for Intel timing.
PAGE 11
DS12R885/DS12CR887/DS12R887 RTCs with Constant-Voltage Trickle Charger Pin Description (continued) PIN SO 18 EDIP 18 BGA A2 NAME FUNCTION RESET Reset Input. The active-low RESET pin has no effect on the clock, calendar, or RAM. On power-up, the RESET pin can be held low for a time to allow the power supply to stabilize. The amount of time that RESET is held low is dependent on the application.
PAGE 12
DS12R885/DS12CR887/DS12R887 RTCs with Constant-Voltage Trickle Charger Detailed Description The DS12R885 is a drop-in replacement for the DS12885 RTC. The device provides 14 bytes of realtime clock/calendar, alarm, and control/status registers and 114 bytes of nonvolatile, battery-backed static RAM. A time-of-day alarm, three maskable interrupts with a common interrupt output, and a programmable square-wave output are available.
PAGE 13
DS12R885/DS12CR887/DS12R887 RTCs with Constant-Voltage Trickle Charger An external 32.768kHz oscillator can also drive the DS12R885. In this configuration, the X1 pin is connected to the external oscillator signal and the X2 pin is left unconnected. Clock Accuracy The accuracy of the clock is dependent upon the accuracy of the crystal and the accuracy of the match between the capacitive load of the oscillator circuit and the capacitive load for which the crystal was trimmed.
PAGE 14
DS12R885/DS12CR887/DS12R887 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 appropriate hours, minutes, and seconds alarm locations, the alarm interrupt is initiated at the specified time each day, if the alarm-enable bit is high.
PAGE 15
DS12R885/DS12CR887/DS12R887 RTCs with Constant-Voltage Trickle Charger Table 2B.
PAGE 16
DS12R885/DS12CR887/DS12R887 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. Control Register A BIT 7 BIT 6 BIT 5 BIT 4 BIT 3 BIT 2 BIT 1 BIT 0 UIP DV2 DV1 DV0 RS3 RS2 RS1 RS0 Bit 7: Update-In-Progress (UIP). This bit is a status flag that can be monitored. When the UIP bit is a 1, the update transfer occurs soon.
PAGE 17
DS12R885/DS12CR887/DS12R887 Control Register B BIT 7 BIT 6 BIT 5 BIT 4 BIT 3 BIT 2 BIT 1 BIT 0 SET PIE AIE UIE SQWE DM 24/12 DSE 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 to 1, any update transfer is inhibited, and the program can initialize the time and calendar bytes without an update occurring in the midst of initializing. Read cycles can be executed in a similar manner.
PAGE 18
DS12R885/DS12CR887/DS12R887 Control Register C BIT 7 BIT 6 BIT 5 BIT 4 BIT 3 BIT 2 BIT 1 BIT 0 IRQF PF AF UF 0 0 0 0 Bit 7: Interrupt Request Flag (IRQF). This bit is set to 1 when any of the following are true: PF = PIE = 1 AF = AIE = 1 UF = UIE = 1 Any time the IRQF bit is 1, the IRQ pin is driven low. This bit can be cleared by reading Register C or with a RESET. Bit 6: Periodic Interrupt Flag (PF).
PAGE 19
DS12R885/DS12CR887/DS12R887 RTCs with Constant-Voltage Trickle Charger Nonvolatile RAM (NV RAM) The 114 general-purpose NV RAM bytes are not dedicated to any special function within the DS12R885. They can be used by the processor program as battery-backed memory and are fully available during the update cycle. Interrupts The DS12R885 includes three separate, fully automatic sources of interrupt for a processor. The alarm interrupt can be programmed to occur at rates from once per second to once per day.
PAGE 20
DS12R885/DS12CR887/DS12R887 RTCs with Constant-Voltage Trickle Charger Table 3. Periodic Interrupt Rate and Square-Wave Output Frequency SELECT BITS REGISTER A tPI PERIODIC INTERRUPT RATE SQW OUTPUT FREQUENCY RS3 RS2 RS1 RS0 0 0 0 0 None None 0 0 0 1 3.90625ms 256Hz 0 0 1 0 7.8125ms 128Hz 0 0 1 1 122.070µs 8.192kHz 0 1 0 0 244.141µs 4.096kHz 0 1 0 1 488.281µs 2.048kHz 0 1 1 0 976.5625µs 1.024kHz 0 1 1 1 1.953125ms 512Hz 1 0 0 0 3.
PAGE 21
DS12R885/DS12CR887/DS12R887 RTCs with Constant-Voltage Trickle Charger Handling, PC Board Layout, and Assembly The EDIP and BGA packages contain a quartz tuningfork crystal. Pick-and-place equipment can be used, but precautions should be taken to ensure that excessive shocks are avoided. Ultrasonic cleaning should be avoided to prevent damage to the crystal. The BGA package can be reflowed as long as the following conditions are met: 1. Preheating (below +160°C) is within 90 seconds. 2.
PAGE 22
DS12R885/DS12CR887/DS12R887 RTCs with Constant-Voltage Trickle Charger Pin Configurations (continued) TOP VIEW (BUMP SIDE DOWN) A DS B VCC C D CS E AD7 GND AD6 DS12R887 AD5 PACKAGE THETA-JA (°C/W) THETA-JC (°C/W) SO 105 22 Chip Information F 1 RESET VCC R/W Thermal Information TRANSISTOR COUNT: 17,061 PROCESS: CMOS SUBSTRATE CONNECTED TO GROUND GND AD4 2 N.C.
PAGE 23
DS12R885/DS12CR887/DS12R887 RTCs with Constant-Voltage Trickle Charger Revision History REVISION NUMBER REVISION DATE 0 4/04 Initial release of DS12R885 — 1 4/04 Added DS12R887 and DS12CR887 to data sheet All 2 12/04 Initial release of DS12R887 All 3 4/06 Corrected Intel Bus Write Timing, Intel Bus Read Timing, IRQ Release Delay Timing, Power-Up/Down Timing, and Functional Diagram diagrams; added the EDIP paragraph to the Handling, PC Board Layout, and Assembly section.