Micro crystal RV-1805-C3 Instructions for use

RV-1805-C3
Application Manual
Date: November 2018
Revision N°: 3.1
1/98
Headquarters:
Micro Crystal AG
Mühlestrasse 14
CH-2540 Grenchen
Switzerland
Tel.
Fax
Internet
Email
[phone]
[phone]
www.microcrystal.com
[e-mail]

Micro Crystal
Extrem Low Power Real Time Clock / Calendar Module RV-1805-C3
2/98
TABLE OF CONTENTS
1. OVERVIEW ........................................................................................................................................................ 6
GENERAL DESCRIPTION......................................................................................................................... 61.1.
APPLICATIONS......................................................................................................................................... 71.2.
2. BLOCK DIAGRAM............................................................................................................................................. 8
PINOUT ...................................................................................................................................................... 92.1.
PIN DESCRIPTION ..................................................................................................................................102.2.
FUNCTIONAL DESCRIPTION.................................................................................................................112.3.
DEVICE PROTECTION DIAGRAM .........................................................................................................112.4.
3. REGISTER ORGANIZATION .......................................................................................................................... 12
REGISTER OVERVIEW........................................................................................................................... 123.1.
TIME AND DATE REGISTERS................................................................................................................143.2.
ALARM REGISTERS............................................................................................................................... 173.3.
CONFIGURATION REGISTERS.............................................................................................................. 203.4.
CALIBRATION REGISTERS...................................................................................................................253.5.
SLEEP CONTROL REGISTER................................................................................................................27
3.6.
TIMER REGISTERS.................................................................................................................................283.7.
OSCILLATOR REGISTERS..................................................................................................................... 313.8.
MISCELLANEOUS REGISTERS............................................................................................................. 323.9.
ANALOG CONTROL REGISTERS ......................................................................................................... 333.10.
ID REGISTERS ........................................................................................................................................ 353.11.
RAM REGISTERS.................................................................................................................................... 373.12.
REGISTER RESET VALUES SUMMARY...............................................................................................393.13.
4. DETAILED FUNCTIONAL DESCRIPTION ..................................................................................................... 40
I2C INTERFACE .......................................................................................................................................414.2.
BUS NOT BUSY................................................................................................................................414.2.1.
BIT TRANSFER ................................................................................................................................ 414.2.2.
START AND STOP CONDITIONS ...................................................................................................414.2.3.
DATA VALID .....................................................................................................................................424.2.4.
SYSTEM CONFIGURATION ............................................................................................................424.2.5.
ACKNOWLEDGE..............................................................................................................................424.2.6.
ADDRESSING...................................................................................................................................434.2.7.
WRITE OPERATION.........................................................................................................................444.2.8.
READ OPERATION AT SPECIFIC ADDRESS................................................................................ 444.2.9.
READ OPERATION..........................................................................................................................454.2.10.
XT OSCILLATOR.....................................................................................................................................454.3.
RC OSCILLATOR .................................................................................................................................... 454.4.
RTC COUNTER ACCESS........................................................................................................................ 454.5.
HUNDREDTHS SYNCHRONIZATION .................................................................................................... 464.6.

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Extrem Low Power Real Time Clock / Calendar Module RV-1805-C3
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GENERATING HUNDREDTHS OF A SECOND ..................................................................................... 464.7.
WATCHDOG TIMER................................................................................................................................ 464.8.
DIGITAL CALIBRATION.......................................................................................................................... 474.9.
XT OSCILLATOR DIGITAL CALIBRATION......................................................................................474.9.1.
RC OSCILLATOR DIGITAL CALIBRATION.....................................................................................484.9.2.
AUTOCALIBRATION...............................................................................................................................504.10.
BASIC AUTOCALIBRATION OPERATION............................................................................................ 504.11.
AUTOCALIBRATION OPERATION..................................................................................................504.11.1.
XT AUTOCALIBRATION MODE.......................................................................................................514.11.2.
RC AUTOCALIBRATION MODE ......................................................................................................514.11.3.
AUTOCALIBRATION FREQUENCY AND CONTROL.....................................................................514.11.4.
Cap_RC PIN......................................................................................................................................524.11.5.
AUTOCALIBRATION FAILURE........................................................................................................524.11.6.
FREQUENCY ACCURACY IN RC AUTOCALIBRATION MODE.....................................................524.11.7.
A REAL WORLD EXAMPLE.............................................................................................................554.11.8.
RC AUTOCALIBRATION TIMING ACCURACY EXAMPLE.............................................................564.11.9.
POWER ANALYSIS...................................................................................................................574.11.10.
DISANDVANTAGES RELATIVE TO THE XT OSCILLATOR ...................................................574.11.11.
XT OSCILLATOR FAILURE DETECTION .............................................................................................. 584.12.
INTERRUPTS........................................................................................................................................... 584.13.
INTERRUPT SUMMARY ..................................................................................................................584.13.1.
ALARM INTERRUPT AIRQ ..............................................................................................................594.13.2.
COUNTDOWN TIMER INTERRUPT TIRQ....................................................................................... 594.13.3.
WATCHDOG TIMER INTERRUPT WIRQ........................................................................................594.13.4.
BATTERY LOW INTERRUPT BLIRQ...............................................................................................594.13.5.
EXTERNAL INTERRUPT EIRQ........................................................................................................594.13.6.
XT OSCILLATOR FAILURE INTERRUPT OFIRQ ...........................................................................594.13.7.
AUTOCALIBRATION FAILURE INTERRUPT ACIRQ......................................................................594.13.8.
SERVICING INTERRUPTS ..............................................................................................................604.13.9.
POWER CONTROL AND SWITCHING...................................................................................................604.14.
AUTOMATIC SWITCHOVER SUMMARY........................................................................................614.14.1.
BATTERY LOW FLAG AND INTERRUPT........................................................................................614.14.2.
ANALOG COMPARATOR ................................................................................................................624.14.3.
PIN CONTROL AND LEAKAGE MANAGEMENT (POWER CONTROL) ........................................ 624.14.4.
POWER UP TIMING......................................................................................................................... 634.14.5.
RESET SUMMARY ..................................................................................................................................634.15.
POWER UP RESET..........................................................................................................................644.15.1.
WATCHDOG TIMER......................................................................................................................... 644.15.2.
SLEEP...............................................................................................................................................654.15.3.

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Extrem Low Power Real Time Clock / Calendar Module RV-1805-C3
4/98
SOFTWARE RESET ................................................................................................................................ 654.16.
SLEEP CONTROL STATE MACHINE .................................................................................................... 654.17.
RUN STATE......................................................................................................................................664.17.1.
SWAIT STATE (SLEEP_WAIT STATE)............................................................................................664.17.2.
SLEEP STATE.................................................................................................................................. 664.17.3.
SLP PROTECTION...........................................................................................................................684.17.4.
PSWS, PSWB AND LKP...................................................................................................................684.17.5.
PIN CONTROL AND LEAKAGE MANAGEMENT (SLEEP CONTROL) ..........................................684.17.6.
SYSTEM POWER CONTROL APPLICATIONS...................................................................................... 694.18.
VSS POWER SWITCHED..................................................................................................................694.18.1.
VDD POWER SWITCHED..................................................................................................................704.18.2.
RESET DRIVEN................................................................................................................................704.18.3.
INTERRUPT DRIVEN.......................................................................................................................714.18.4.
TYPICAL SYSTEM IMPLEMENTATION................................................................................................. 714.19.
ALARMS............................................................................................................................................ 724.19.1.
COUNTDOWN TIMER......................................................................................................................724.19.2.
WAKE BUTTON/SWITCH.................................................................................................................724.19.3.
EXTERNAL DEVICE INPUT.............................................................................................................724.19.4.
ANALOG INPUT................................................................................................................................724.19.5.
BATTERY LOW DETECTION...........................................................................................................724.19.6.
ERRORS...........................................................................................................................................724.19.7.
SAVING PARAMETERS..........................................................................................................................734.20.
POWER SWITCH ELECTRICAL CHARACTERISTICS ......................................................................... 734.21.
AVOIDING UNEXPECTED LEAKAGE PATHS ......................................................................................734.22.
SYSTEM POWER ANALYSIS................................................................................................................. 734.23.
USING AN EXTERNAL RTC WITH POWER MANAGEMENT.........................................................734.23.1.
MANAGING MCU ACTIVE POWER................................................................................................. 744.23.2.
LOWER COST MCUs.......................................................................................................................744.23.3.
HIGH PERFORMANCE PROCESSORS.......................................................................................... 744.23.4.
TRICKLE CHARGER............................................................................................................................... 744.24.
5. DIGITAL ARCHITECTURE SUMMARY ..........................................................................................................75
6. ELECTRICAL SPECIFICATIONS....................................................................................................................76
ABSOLUTE MAXIMUM RATINGS.......................................................................................................... 766.1.
POWER SUPPLY PARAMETERS ..........................................................................................................766.2.
OPERATING PARAMETERS .................................................................................................................. 786.3.
OSCILLATOR PARAMETERS................................................................................................................786.4.
XT FREQUENCY CHARACTERISTICS..................................................................................................806.5.
XT FREQUENCY VS. TEMPERATURE CHARACTERISTICS........................................................806.5.1.
VDD SUPPLY CURRENT.......................................................................................................................... 816.6.

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Extrem Low Power Real Time Clock / Calendar Module RV-1805-C3
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VBACKUP SUPPLY CURRENT ...................................................................................................................856.7.
BREF ELECTRICAL CHARACTERISTICS............................................................................................. 886.8.
I2C AC ELECTRICAL CHARACTERISTICS ...........................................................................................896.9.
POWER ON AC ELECTRICAL CHARACTERISTICS............................................................................ 906.10.
RST
AC ELECTRICAL CHARACTERISTICS........................................................................................ 916.11.
7. APPLICATION INFORMATION....................................................................................................................... 92
OPERATING RV-1805-C3 .......................................................................................................................927.1.
OPERATING RV-1805-C3 WITH BACKUP BATTERY/SUPERCAP ..................................................... 937.2.
8. RECOMMENDED REFLOW TEMPERATURE (LEADFREE SOLDERING)..................................................94
9. PACKAGE........................................................................................................................................................95
DIMENSIONS AND SOLDERPADS LAYOUT ........................................................................................959.1.
MARKING AND PIN #1 INDEX................................................................................................................959.2.
10.PACKING & SHIPPING INFORMATION.........................................................................................................96
11.HANDLING PRECAUTIONS FOR CRYSTALS OR MODULES WITH EMBEDDED CRYSTALS ................ 97
12.DOCUMENT REVISION HISTORY..................................................................................................................98

Micro Crystal
Extrem Low Power Real Time Clock / Calendar Module RV-1805-C3
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RV-1805-C3
Extreme Low Power Real Time Clock / Calendar Module with I2C Interface
1. OVERVIEW
Ultra-low supply current (all at 3V):
- 17 nA with RC oscillator
- 22 nA with RC oscillator and Autocalibration (ACP = 512 seconds)
- 60 nA with crystal oscillator
Baseline timekeeping features:
- 32.768 kHz built-in “Tuning Fork” crystal oscillator with integrated load capacitor/resistor
- Counters for hundredths, seconds, minutes, hours, date, month, year, century, and weekday
- Alarm capability on all counters
- Programmable output clock generation (32.768 kHz to 1/year)
- Countdown timer with repeat function
- Automatic leap year calculation
Advanced timekeeping features:
- Integrated power optimized RC oscillator
- Factory calibrated frequency offset compensation to ± 2 ppm
- Advanced RC calibration to ± 16 ppm
- Automatic calibration of RC oscillator to the compensated crystal oscillator
- Watchdog timer with hardware reset
- Up to 512 bytes of general purpose RAM
Power management features:
- Integrated ~1 Ω power switch for off-chip components such as a host MCU
- System sleep manager for managing host processor wake/sleep states
- Reset output generator
- Supercapacitor trickle charger with programmable charging current
- Automatic switchover to VBACKUP
- External interrupt monitor
- Programmable low battery detection threshold
- Programmable analog voltage comparator
I2C (up to 400 kHz) serial interface
Operating voltage 1.5-3.6 V
Clock and RAM retention voltage 1.5-3.6 V
Operating temperature –40 to +85 °C
All inputs include Schmitt Triggers
Available in small and compact package size, RoHS-compliant and 100% leadfree: C3: 3.7 x 2.5 x 0.9 mm
GENERAL DESCRIPTION1.1.
The RV-1805-C3 Real Time Clock with Power Management provides a groundbreaking combination of ultra-low
power coupled with a highly sophisticated feature set. The power requirement is significantly lower than any other
industry RTC (as low as 17 nA). The RV-1805-C3 includes an on-chip oscillator to provide a minimum power
consumption, full RTC functions including battery backup and programmable counters and alarms for timer and
watchdog functions, and either an I2C serial interface for communication with a host controller. An integrated power
switch and a sophisticated system sleep manager with counter, timer, alarm, and interrupt capabilities allows the
RV-1805-C3 to be used as a supervisory component in a host microcontroller based system.

Micro Crystal
Extrem Low Power Real Time Clock / Calendar Module RV-1805-C3
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APPLICATIONS1.2.
The RV-1805-C3 RTC module has been specially designed for ultimate low power consumption:
60 nA with crystal oscillator (at 3V)
22 nA with RC oscillator and Autocalibration (ACP = 512 sec. at 3V)
17 nA with RC oscillator (at 3V)
Permits to operate this RTC module several hours at Backup Supply Voltage using low-cost MLCC
These unique features make this product perfectly suitable for many applications:
Communication: Wireless Sensors and Tags, Handsets, Communications equipment
Metering: E-Meter / Heating Counter / Smart Meters / PV Converter
Outdoor: ATM & POS systems / Ticketing Systems
Medical: Glucose Meter / Health Monitoring Systems
Safety: Security & Camera Systems / Door Lock & Access Control
Consumer: Gambling Machines / TV & Set Top Boxes / White Goods
Automation: Data Logger / Home & Factory Automation / Industrial and Consumer Electronics

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Extrem Low Power Real Time Clock / Calendar Module RV-1805-C3
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2. BLOCK DIAGRAM
Cap_RC Control
Trickle Charge
BREF Control
Batmode IO
Analog Status
Output Control
Ext. RAM Addr.
User RAM
1D
00
17
14
20
26
2F
08
0F
10
3F
40
FF
Hundredths
Hours
Interrupt Mask
Control2
Control1
Status
Weekdays Alarm
Months Alarm
Hours Alarm
Minutes Alarm
Seconds Alarm
Hundredths Alarm
Weekdays
Years
Months
Minutes
Seconds
Timer Control
Sleep Control
Calibration XT
Square Wave SQW
Date Alarm
Oscillator Status
Oscillator Control
Timer Initial
Timer
Watchdog Timer
Date
System Control
logic
PSW 8
INPUT
OUTPUT
CONTROL
WDI 9
10
RST
3
Reset
Cap_RC 2
Xtal Osc
RC Osc
Divider
Divider
Calibration Engine
I2C-BUS
Interface
SCL 4
SDA 5
VSS 6
VDD 1Power
Control
7
VBACKUP
Analog
Compare
CLK/INT

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Extrem Low Power Real Time Clock / Calendar Module RV-1805-C3
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PINOUT2.1.
RV-1805-C3 Package:
#1 #5
#6#10
1805
#1 VDD
#10
RST
#2 Cap_RC
#9 WDI
#3 CLK/INT
#8 PSW
#4 SCL
#7 VBACKUP
#5 SDA
#6 VSS

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Extrem Low Power Real Time Clock / Calendar Module RV-1805-C3
10/98
PIN DESCRIPTION2.2.
Symbol
Pin #
Description
VDD
1
Primary power connection. If a single power supply is used, it must be connected to VDD.
Cap_RC
2
Autocalibration filter connection. A 47 pF ceramic capacitor should be placed between this pin and VSS for
improved Autocalibration mode timing accuracy.
INT/CLK
3
Clock Output / Interrupt. Primary interrupt output connection. It is an open drain output. An external pull-up
resistor must be added to this pin. It should be connected to the host device and is used to indicate when
the RTC can be accessed via the I2C interface.
INT/CLK
may be configured to generate several signals
as a function of the CLKS field (see CONFIGURATION REGISTERS, 11h - Control2).
INT/CLK
is also
asserted low on a power up until the RV-1805-C3 has exited the reset state and is accessible via the I2C
interface.
1.
INT/CLK
can drive the static value of the CLKB bit.
2.
INT/CLK
can drive the inverse of the combined interrupt signal IRQ (see INTERRUPTS).
3.
INT/CLK
can drive the square wave signal SQW (see CONFIGURATION REGISTERS, 13h –
Square Wave SQW) if enabled by SQWE.
4.
INT/CLK
can drive the inverse of the alarm interrupt signal AIRQ (see INTERRUPTS).
SCL
4
I2C Serial Clock Input. A pull-up resistor is required on this pin.
SDA
5
I2C Serial Data. A pull-up resistor is required on this pin.
VSS
6
Ground connection
VBACKUP
7
Backup Supply Voltage. If a backup voltage is not present, VBACKUP is normally left floating or grounded, but
it may also be used to provide the analog input to the internal comparator (see ANALOG COMPARATOR).
Requires series resistor. The optimal total series impedance = VBACKUP power source ESR (Equivalent
Series Resistance) + external resistor value = 1.5 kΩ.
PSW
8
Power Switch Output. Secondary interrupt output connection. It is an open drain output. This pin can be left
floating if not used. PSW may be configured to generate several signals as a function of the PSWS field
(see CONFIGURATION REGISTERS, 11h - Control2). This pin will be configured as an ~1 Ω switch if the
PSWC bit is set.
1. PSW can drive the static value of the PSWB bit.
2. PSW can drive the square wave signal SQW (see CONFIGURATION REGISTERS, 13h -
Square Wave SQW) if enabled by SQWE.
3. PSW can drive the inverse of the combined interrupt signal IRQ (see INTERRUPTS).
4. PSW can drive the inverse of the alarm interrupt signal AIRQ (see INTERRUPTS).
5. PSW can drive the inverse or the not inverse of the timer interrupt signal TIRQ.
6. PSW can function as the power switch output for controlling the power of external devices (see
SLEEP CONTROL).
WDI
9
Watchdog Timer reset input connection. It may also be used to generate an External interrupt with polarity
selected by the EIP bit if enabled by the EIE bit. The value of the WDI pin may be read in the WDIS register
bit. This pin does not have an internal pull-up or pull-down resistor and so one must be added externally. It
must not be left floating or the RTC may consume higher current. Instead, it must be connected directly to
either VDD or VSS if not used.
RST
10
Reset Output. It is an open drain output. If this pin is used, an external pull-up resistor must be added to
this pin. If the pin is not used, it can be left floating. The polarity is selected by the RSTP bit, which will
initialize to 0 on power up to produce an active low output. See AUTOCALIBRATION FAILURE
INTERRUPT ACIRQ for details of the generation of
RST
.

Micro Crystal
Extrem Low Power Real Time Clock / Calendar Module RV-1805-C3
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FUNCTIONAL DESCRIPTION2.3.
The RV-1805-C3 is an extreme low power CMOS Real-Time Clock / Calendar module with built-in “Tuning-Fork”
crystal with the nominal frequency of 32.768 kHz and an on-chip auto-calibrated RC-oscillator; no external
components are required for the oscillator circuitry.
The oscillator frequency on all devices is tested not to exceed a time deviation of ± 20 ppm (parts per million) at
25°C, which equates to about ± 52 seconds per month.
This time accuracy can be further improved to ± 2 ppm (factory calibrated at 25°C) or better by individually
measuring the frequency-deviation in the application at a given temperature and programming a correction value
into the frequency compensation register.
Up to 512 bytes/registers of general purpose ultra-low leakage RAM enable the storage of key parameters when
operating on backup power.
The registers are accessed by selecting a register address and then performing read or write operations. Multiple
reads or writes may be executed in a single access, with the address automatically incrementing after each byte.
DEVICE PROTECTION DIAGRAM2.4.
The following Figure illustrates the internal ESD structure. The ESD Clamp devices are not simple diodes and are
more complex structured. The VDD, VBACKUP and Cap_RC pins have these ESD clamps as well as the internal VSYS
supply, which route a positive ESD discharge to VSS. Note that the VSYS internal supply is switched between the VDD
and VBACKUP supplies dependent upon the mode of operation. In VBACKUP mode (when VDD goes away with a VBACKUP
supply present), the internal VSYS supply is switched to VBACKUP by additional internal circuitry. In VDD mode (when
VDD is present and regardless if a supply is present on VBACKUP or not), the internal VSYS supply is switched to VDD
by additional internal circuitry. Note that VSYS does not directly touch a pin, but all of the positive charge injected
onto the other digital I/O pads (
INT/CLK
, SCL, SDA, PSW, WDI and
RST
) gets routed to this ESD clamp on
VSYS. In addition, there are simple diodes between VSYS and VSS as well as between the digital I/O pads and VSS as
shown in the diagram. These diodes take care of negative discharges to any of those pads.
Internal ESD structure:
ESD
Clamp
ESD
Clamp
ESD
Clamp ESD Clamp
VBACKUP VSYS (internal supply)
7
VSS
6
CLK/INT
RST
ESD
Clamp
VDD
1
All I/Os including:
3
4SCL
5SDA
8PSW
9WDI
10
Cap_RC
2

Micro Crystal
Extrem Low Power Real Time Clock / Calendar Module RV-1805-C3
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3. REGISTER ORGANIZATION
Registers are accessed by selecting a register address and then performing read or write operations. Multiple
reads or writes may be executed in a single access, with the address automatically incrementing after each byte.
The following tables Register Definitions (00h to 0Fh) and Register Definitions (10h to FFh) summarize the function
of each register. In the table Register Definitions (00h to 0Fh), the GPx bits (where x is between 0 and 27) are 28
register bits which may be used as general purpose storage. These bits are not described in the sections below. All
of the GPx bits are cleared when the RV-1805-C3 powers up, and they can therefore be used to allow software to
determine if a true Power On Reset (POR) has occurred or hold other initialization data.
REGISTER OVERVIEW3.1.
Register Definitions (00h to 0Fh):
Address
Function
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
00h
Hundredths
80
40
20
10
8
4
2
1
01h
Seconds
GP0
40
20
10
8
4
2
1
02h
Minutes
GP1
40
20
10
8
4
2
1
03h
Hours (24 hour)
GP3
GP2
20
10
8
4
2
1
Hours (12 hour)
GP3
GP2
AM/PM
10
8
4
2
1
04h
Date
GP5
GP4
20
10
8
4
2
1
05h
Months
GP8
GP7
GP6
10
8
4
2
1
06h
Years
80
40
20
10
8
4
2
1
07h
Weekdays
GP13
GP12
GP11
GP10
GP9
4
2
1
08h
Hundredths Alarm
80
40
20
10
8
4
2
1
09h
Seconds Alarm
GP14
40
20
10
8
4
2
1
0Ah
Minutes Alarm
GP15
40
20
10
8
4
2
1
0Bh
Hours Alarm (24 hour)
GP17
GP16
20
10
8
4
2
1
Hours Alarm (12 hour)
GP17
GP16
AM/PM
10
8
4
2
1
0Ch
Date Alarm
GP19
GP18
20
10
8
4
2
1
0Dh
Months Alarm
GP22
GP21
GP20
10
8
4
2
1
0Eh
Weekdays Alarm
GP27
GP26
GP25
GP24
GP23
4
2
1
0Fh
Status
CB
BAT
WDF
BLF
TF
AF
EVF
X

Micro Crystal
Extrem Low Power Real Time Clock / Calendar Module RV-1805-C3
13/98
Register Definitions (10h to FFh):
Address
Function
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
10h
Control1
STOP
12/24
PSWB
CLKB
RSTP
ARST
PSWC
WRTC
11h
Control2
RESERVED
X
PSWS
CLKS
12h
Interrupt Mask
CBE
IM
BLIE
TIE
AIE
EIE
X
13h
Square Wave SQW
SQWE
RESERVED
SQWS
14h
Calibration XT
CMDX
OFFSETX
15h
Calibration RC Upper
CMDR
OFFSETRU[13:8]
16h
Calibration RC Lower
OFFSETRL[7:0]
17h
Sleep Control
SLP
SLRST
EIP
X
SLF
SLW
18h
Countdown Timer
Control
TE
TM
TRPT
ARPT
TFS
19h
Countdown Timer
128
64
32
16
8
4
2
1
1Ah
Timer Initial Value
128
64
32
16
8
4
2
1
1Bh
Watchdog Timer
WDS
WDM
WD
1Ch
Oscillator Control
OSEL
ACAL
BOS
FOS
IOPW
OFIE
ACIE
1Dh
Oscillator Status Register
XTCAL
LKP
OMODE
RESERVED
OF
ACF
1Eh
RESERVED
RESERVED
1Fh
Configuration Key
CONFKEY
20h
Trickle Charge
TCS
DIODE
ROUT
21h
BREF Control
BREF
RESERVED
22h
RESERVED
RESERVED
23h
RESERVED
RESERVED
24h
RESERVED
RESERVED
25h
RESERVED
RESERVED
26h
Cap_RC Control
CAPRC
27h
IO Batmode Register
IOBM
RESERVED
28h
ID0 (Read only)
Part Number –MS Byte = 00011000 (18h)
29h
ID1 (Read only)
Part Number –LS Byte = 00000101 (05h)
2Ah
ID2 (Read only)
Revision –Major = 00010
Revision –Minor = 011
2Bh
ID3 (Read only)
Lot[7:0]
2Ch
ID4 (Read only)
Lot[9]
Unique ID[14:8]
2Dh
ID5 (Read only)
Unique ID[7:0]
2Eh
ID6 (Read only)
Lot[8]
Wafer
RESERVED
2Fh
Analog Stat. (Read Only)
BREFD
BMIN
RESERVED
VINIT
RESERVED
30h
Output Control Register
WDBM
X
WDDS
X
RSTSL
X
X
CLKSL
3Fh
Extension RAM Address
X
BPOL
WDIS
X
RESERVED
XADA
XADS
40h
:
7Fh
Standard RAM
RAM data (4 x 64 bytes = 256 bytes)
80h
:
FFh
Alternate RAM
RAM data (2 x 128 bytes = 256 bytes)

Micro Crystal
Extrem Low Power Real Time Clock / Calendar Module RV-1805-C3
14/98
TIME AND DATE REGISTERS3.2.
00h - Hundredths
This register holds the count of hundredths of seconds, in two binary coded decimal (BCD) digits. Values will be
from 00 to 99. Note that in order to divide from 32.768 kHz, the hundredths register will not be fully accurate at all
times but will be correct every 500 ms. Maximum jitter of this register will be less than 1 ms. The Hundredths
Counter is not valid if the RC Oscillator is selected.
Address
Function
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
00h
Hundredths
80
40
20
10
8
4
2
1
Reset
1
0
0
1
1
0
0
1
Bit
Symbol
Value
Description
7:0
Hundredths
00 to 99
Holds the count of hundredths of seconds, coded in BCD format.
01h - Seconds
This register holds the count of seconds, in two binary coded decimal (BCD) digits. Values will be from 00 to 59.
Address
Function
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
01h
Seconds
GP0
40
20
10
8
4
2
1
Reset
0
0
0
0
0
0
0
0
Bit
Symbol
Value
Description
7
GP0
0 or 1
Register bit for general purpose use.
6:0
Seconds
00 to 59
Holds the count of seconds, coded in BCD format.
02h –Minutes
This register holds the count of minutes, in two binary coded decimal (BCD) digits. Values will be from 00 to 59.
Address
Function
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
02h
Minutes
GP1
40
20
10
8
4
2
1
Reset
0
0
0
0
0
0
0
0
Bit
Symbol
Value
Description
7
GP1
0 or 1
Register bit for general purpose use.
6:0
Minutes
00 to 59
Holds the count of minutes, coded in BCD format.

Micro Crystal
Extrem Low Power Real Time Clock / Calendar Module RV-1805-C3
15/98
03h - Hours
This register holds the count of hours, in two binary coded decimal (BCD) digits. Values will be from 00 to 23 if the
12/24 bit (see CONFIGURATION REGISTERS, 10h - Control1) is clear. If the 12/24 bit is set, the AM/PM bit will be
0 for AM hours and 1 for PM hours, and hour values will range from 1 to 12.
Hours Register (24 Hour Mode)
Address
Function
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
03h
Hours
GP3
GP2
20
10
8
4
2
1
Reset
0
0
0
0
0
0
0
0
Bit
Symbol
Value
Description
7
GP3
0 or 1
Register bit for general purpose use.
6
GP2
0 or 1
Register bit for general purpose use.
5:0
Hours
00 to 23
Holds the count of hours, coded in BCD format.
Hours Register (12 Hour Mode)
Address
Function
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
03h
Hours
GP3
GP2
AM/PM
10
8
4
2
1
Reset
0
0
0
0
0
0
0
0
Bit
Symbol
Value
Description
7
GP3
0 or 1
Register bit for general purpose use.
6
GP2
0 or 1
Register bit for general purpose use.
5
AM/PM
0
AM hours.
1
PM hours.
4:0
Hours
1 to 12
Holds the count of hours, coded in BCD format.
04h –Date
This register holds the current day of the month, in two binary coded decimal (BCD) digits. Values will range from
01 to 31. Leap years are correctly handled from 1900 to 2199.
Address
Function
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
04h
Date
GP5
GP4
20
10
8
4
2
1
Reset
0
0
0
0
0
0
0
1
Bit
Symbol
Value
Description
7
GP5
0 or 1
Register bit for general purpose use.
6
GP4
0 or 1
Register bit for general purpose use.
5:0
Date
01 to 31
Holds the current day of the month, coded in BCD format.

Micro Crystal
Extrem Low Power Real Time Clock / Calendar Module RV-1805-C3
16/98
05h - Months
This register holds the current month, in two binary coded decimal (BCD) digits. Values will range from 01 to 12.
Address
Function
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
05h
Months
GP8
GP7
GP6
10
8
4
2
1
Reset
0
0
0
0
0
0
0
1
Bit
Symbol
Value
Description
7
GP8
0 or 1
Register bit for general purpose use.
6
GP7
0 or 1
Register bit for general purpose use.
5
GP6
0 or 1
Register bit for general purpose use.
4:0
Months
01 to 12
Holds the current month, coded in BCD format.
06h - Years
This register holds the current year, in two binary coded decimal (BCD) digits. Values will range from 00 to 99.
Address
Function
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
06h
Years
80
40
20
10
8
4
2
1
Reset
0
0
0
0
0
0
0
0
Bit
Symbol
Value
Description
7:0
Years
00 to 99
Holds the current year, coded in BCD format.
When the Years register rolls over from 99 to 00 the Century bit CB will be
toggled (see CONFIGURATION REGISTERS, 0Fh - Status) if the CBE bit
is a 1 (see CONFIGURATION REGISTERS,12h - Interrupt Mask).
07h - Weekdays
This register holds the current day of the week. Values will range from 0 to 6.
Address
Function
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
07h
Weekdays
GP13
GP12
GP11
GP10
GP09
4
2
1
Reset
0
0
0
0
0
0
0
0
Bit
Symbol
Value
Description
7
GP13
0 or 1
Register bit for general purpose use.
6
GP12
0 or 1
Register bit for general purpose use.
5
GP11
0 or 1
Register bit for general purpose use.
4
GP10
0 or 1
Register bit for general purpose use.
3
GP09
0 or 1
Register bit for general purpose use.
2:0
Weekdays
0 to 6
Holds the weekday counter value.

Micro Crystal
Extrem Low Power Real Time Clock / Calendar Module RV-1805-C3
17/98
ALARM REGISTERS3.3.
08h - Hundredths Alarm
This register holds the alarm value for hundredths of seconds, in two binary coded decimal (BCD) digits. Values will
range from 00 to 99. It holds the special values FFh and (F0h to F9h) when ARPT bit is 7. See TIMER
REGISTERS, 18h - Countdown Timer Control.
Address
Function
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
08h
Hundredths Alarm
80
40
20
10
8
4
2
1
Reset
0
0
0
0
0
0
0
0
Bit
Symbol
Value
Description
7:0
Hundredths Alarm
FFh
Once per hundredth in XT mode. Once per second in RC mode. ARPT bit
must be 7.
F0h to
F9h
Once per tenth in XT mode. Once per second in RC mode. ARPT bit must
be 7.
00 to 99
Holds the alarm value for hundredths of seconds, coded in BCD format. If
the ARPT bit is 0 to 6.
09h - Seconds Alarm
This register holds the alarm value for seconds, in two binary coded decimal (BCD) digits. Values will range from
00 to 59.
Address
Function
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
09h
Seconds Alarm
GP14
40
20
10
8
4
2
1
Reset
0
0
0
0
0
0
0
0
Bit
Symbol
Value
Description
7
GP14
0 or 1
Register bit for general purpose use.
6:0
Seconds Alarm
00 to 59
Holds the alarm value for seconds, coded in BCD format.
0Ah - Minutes Alarm
This register holds the alarm value for minutes, in two binary coded decimal (BCD) digits. Values will range from
00 to 59.
Address
Function
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
0Ah
Minutes Alarm
GP15
40
20
10
8
4
2
1
Reset
0
0
0
0
0
0
0
0
Bit
Symbol
Value
Description
7
GP15
0 or 1
Register bit for general purpose use.
6:0
Minutes Alarm
00 to 59
Holds the alarm value for minutes, coded in BCD format.

Micro Crystal
Extrem Low Power Real Time Clock / Calendar Module RV-1805-C3
18/98
0Bh - Hours Alarm
This register holds the alarm value for hours, in two binary coded decimal (BCD) digits. Values will range from 00
to 23 if the 12/24 bit (see CONFIGURATION REGISTERS, 10h - Control1) is clear. If the 12/24 bit is set, the
AM/PM bit will be 0 for AM hours and 1 for PM hours, and hour values will be from 1 to 12.
Hours Alarm Register (24 Hour Mode)
Address
Function
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
0Bh
Hours Alarm
GP17
GP16
20
10
8
4
2
1
Reset
0
0
0
0
0
0
0
0
Bit
Symbol
Value
Description
7
GP17
0 or 1
Register bit for general purpose use.
6
GP16
0 or 1
Register bit for general purpose use.
5:0
Hours Alarm
00 to 23
Holds the alarm value for hours, coded in BCD format.
Hours Alarm Register (12 Hour Mode)
Address
Function
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
0Bh
Hours Alarm
GP17
GP16
AM/PM
10
8
4
2
1
Reset
0
0
0
0
0
0
0
0
Bit
Symbol
Value
Description
7
GP17
0 or 1
Register bit for general purpose use.
6
GP16
0 or 1
Register bit for general purpose use.
5
AM/PM
0
AM hours.
1
PM hours.
4:0
Hours Alarm
1 to 12
Holds the alarm value for hours, coded in BCD format.
0Ch - Date Alarm
This register holds the alarm value for the date, in two binary coded decimal (BCD) digits. Values will range from
01 to 31. Leap years are correctly handled from 1900 to 2199.
Address
Function
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
0Ch
Date Alarm
GP19
GP18
20
10
8
4
2
1
Reset
0
0
0
0
0
0
0
0
Bit
Symbol
Value
Description
7
GP19
0 or 1
Register bit for general purpose use.
6
GP18
0 or 1
Register bit for general purpose use.
5:0
Date Alarm
01 to 31
Holds the alarm value for the date, coded in BCD format.

Micro Crystal
Extrem Low Power Real Time Clock / Calendar Module RV-1805-C3
19/98
0Dh - Months Alarm
This register holds the alarm value for months, in two binary coded decimal (BCD) digits. Values will range from 01
to 12.
Address
Function
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
0Dh
Months Alarm
GP22
GP21
GP20
10
8
4
2
1
Reset
0
0
0
0
0
0
0
0
Bit
Symbol
Value
Description
7
GP22
0 or 1
Register bit for general purpose use.
6
GP21
0 or 1
Register bit for general purpose use.
5
GP20
0 or 1
Register bit for general purpose use.
4:0
Months Alarm
01 to 12
Holds the alarm value for months, coded in BCD format.
0Eh - Weekdays Alarm
This register holds the alarm value for the day of the week. Values will range from 0 to 6.
Address
Function
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
0Eh
Weekdays Alarm
GP27
GP26
GP25
GP24
GP23
4
2
1
Reset
0
0
0
0
0
0
0
0
Bit
Symbol
Value
Description
7
GP27
0 or 1
Register bit for general purpose use.
6
GP26
0 or 1
Register bit for general purpose use.
5
GP25
0 or 1
Register bit for general purpose use.
4
GP24
0 or 1
Register bit for general purpose use.
3
GP23
0 or 1
Register bit for general purpose use.
2:0
Weekdays Alarm
0 to 6
Holds the weekdays alarm value.

Micro Crystal
Extrem Low Power Real Time Clock / Calendar Module RV-1805-C3
20/98
CONFIGURATION REGISTERS3.4.
0Fh –Status
This register holds a variety of status bits. The register may be written at any time to clear or set any status flag. If
the ARST bit is set (see 10h - Control1), any read of the Status Register will clear interrupt flags in this register
(WDF, BLF, TF, AF and EVF). The bits CB and BAT are not affected.
Address
Function
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
0Fh
Status
CB
BAT
WDF
BLF
TF
AF
EVF
X
Reset
0
0
0
0
0
0
0
0
Bit
Symbol
Value
Description
7
CB
Century bit. This bit will be toggled when the Years register rolls over from 99 to 00 if
the CBE bit is a 1 (see 12h - Interrupt Mask register).
Assuming that the current Year is in the 20xx century the CB bit has to be set to 1.
0
Assumes the century is 19xx or 21xx. –Default value
1
Assumes it is 20xx for leap year calculations.
6
BAT
(read only) –VBACKUP Power state
0
System is in POR or VDD Power state.
1
System is in VBACKUP Power state.
5
WDF
Watchdog Timer Flag
0
No Watchdog Timer timeout trigger detected.
1
The Watchdog Timer is enabled and is triggered, and the WDS bit is 0 (see
TIMER REGISTERS, 1Bh Watchdog Timer).
4
BLF
Battery Low Flag
0
No crossing of the reference voltage detected.
1
The battery voltage VBACKUP crossed the reference voltage selected by
BREF (see ANALOG CONTROL REGISTERS, 21h - BREF Control) in the
direction selected by BPOL (see RAM REGISTERS, 3Fh - Extension RAM
Address).
3
TF
Countdown Timer Flag
0
No zero detected.
1
Countdown Timer is enabled and reaches zero.
2
AF
Alarm Flag
0
No match detected.
1
The Alarm function is enabled and all selected Alarm registers match their
respective counters.
1
EVF
External Event Flag
0
No external trigger detected.
1
An external trigger is detected on the WDI pin. The EIE bit (see
CONFIGURATION REGISTERS , 12h - Interrupt Mask) must be set in
order for this interrupt to occur, but subsequently clearing EIE will not
automatically clear this flag.
0
X
0
Unused flag. Always 0.