Serial RTC with Alarm and Timer
RTC - 4573
·
Built-in frequency adjusted 32.768KHz crystal oscillator
·
Serial interface that can be controlled through three signal lines
·
Week , Day , hour , and minute alarm interrupt functions
·
Interval timer interrupt function that can be set with an interval ranging from 1/4096th of a second to 255minutes
·
Dual dedicated interrupt outputs for software maskable alarms and for timers
·
Functions that detect halting of crystal oscillation, and when the time is being updated
·
Automatic leap year compensation function
·
Wide interface voltage range, from 1.6 to 5.5V
·
Wide timing voltage range, from 1.6 to 5.5V
·
Low current consumption : 0.5
m
A/3V (typ.)
·
Small SOP package suited for high-density mounting
n
Overview
This module is a serial interface-type real-time clock with a crystal oscillator on chip. This module includes clock
and calendar circuitry (from seconds to years) with automatic leap year compensation, alarms, and timer interrupt
functions, as well as functions that detect when oscillation is halted, the time is being updated. The serial
interface permits control through three signal lines, keeping the number of ports required on the system side to a
minimum. Because the small SOP package can be used in high-density mounting, this module is ideal for
portable telephones, hand-held terminals, and other compact electronic equipment.
n
Block Diagram
32.768KHz
CONTROL LINE
OSC
DIVIDER
CLOCK and
CALENDAR
FOUT
OUTPUT
CONTROLLER
TIMER
REGISTER
/ TIRQ
/ AIRQ
DATA
CLK
C E1
C E0
INTERRUPTS
CONTROLLER
ALARM
REGISTER
BUS
INTERFACE
CIRCUIT
CONTROL
REGISTER
SHIFT REGISTER
Page-1
Aug. 1998
n
Pin Connection
1. N.C
2. N.C
3 N.C
4 N.C
5 CE1
6 DATA
7. CLK
8. N.C
9 GND
18 N.C
#1
#18
17 N.C
16 N.C
15 N.C
14 V
DD
13 FOUT
12 CE0
11. / AIRQ
#9
#10
10 / TIRQ
Symbol
Pin-No.
I/O
Function
CE1
5
DATA
6
CLK
GND
/ TIRQ
/ AIRQ
7
9
10
11
Chip enable 1 input pin.
This terminal has pull-down resistor built-in. Access to this RTC is possible in
Input
"H" level both CE0,CE1 terminal. FOUT terminal can output frequency when
inputs "H" level into this terminal regardless of state of CE0 terminal. FOUT
terminal is high impedance state in input "L" level.
This I/O pin is used to for setting write mode/read mode, for writing an
Bi-
address, and for reading and writing data. This pin functions either as an
directional input pin or an output pin, according to the write mode/read mode setting
made in the first 8 bits of input data following the rising edge of the CE input.
Shift clock input pin. In write mode, the data is read from the DATA pin at
Input
the rising edge of the CLK signal; in read mode, the data is output from the
DATA pin at the rising edge of the CLK signal.
-
Connect to the negative (ground) line of the power supply.
Output
Output
Open drain interrupt output pin for the interval timer.
Output Open drain interrupt output pin for alarms.
Chip enable 0 input pin.
When high, access to the internal registers is enabled. While low, the
DATA pin goes to high impedance. When the CE pin is set low, the fr, TEST,
and RESET bits are forcibly cleared to "0".Set this pin low when turning the
power on, when the device is not to be accessed, and when using the
backup power supply. This pin does not affect FOUT terminal.
Frequency output terminal. Frequency is selectable by software.
Connect to the positive line of the power supply.
Access is possible between 1.6 and 5.5V
CE0
12
Input
FOUT
V
DD
13
14
Output
-
1,2,3,
4,8,
Although these pins are not connected internally, they should always be left
15,16,
open in order to obtain the most stable oscillation possible.
17,18
* Always connect a passthrough capacitor of at least 0.1
m
F as close as possible between V
DD
and GND.
N.C.
Page-2
Aug.1998
n
Electrical Characteristics
1. Absolute Maximum Ratings
Description
Power supply Voltage
Input Voltage
Output Voltage
Temperature
Symbol
V
DD
V
IN1
V
OUT1
V
OUT2
T
STG
Conditions
-
input pins
/ TIRQ,/ AIRQ
FOUT,DATA
-
Rated values
-0.3 to +7.0
GND-0.3 to V
DD
+0.3
-0.3 to +8.0
GND-0.3 to V
DD
+0.3
-55 to +125
Unit
V
V
V
°C
2. Operating Condition
Item
Supply Voltage
Data Holding Voltage
Operating Temperature Range
Symbol
V
DD
V
CLK
T
OPR
Conditions
-
-
-
MIN.
1.6
1.6
MAX.
5.5
5.5
+85
Unit
V
V
°
C
3. Frequency Characteristics
Item
Frequency accuracy
Oscillator start up time
Temperature characteristics
Voltage characteristics
* Monthly error of about 1 minute
Symbol
f / fo
t
STA
Conditions
Ta=25
°C,V
DD
=3V
Ta=25°C,V
DD
=1.6V
-10 to 70
°C
25
°C(Typ)
Ta=25°C,V
DD
=1.6 to 5.5V
Specifications
5 ± 23 *
3 (MAX)
+10 / -120
± 2.0
Unit
ppm
sec
ppm
ppm / V
4. DC Characteristics
Description
Standby current 1
Standby current 2
Input Voltage
Input leakage current
PulIdown R 1
PulIdown R 2
Symbol
I
DD1
I
DD2
VIH
VIL
I
LK
R
DWN1
R
DWN2
V
OH1
V
OH2
V
OH3
V
OL1
V
OL2
V
OL3
Output voltage 2
Leakage current
V
OL4
V
OL5
I
OZ
Conditions
V
DD
=5V
CE0,CE1=GND
V
DD
=3V
CE0,CE1=GND
CE0,CE1
CLK,DATA pins
VI=V
DD
or GND
CLK pins
V
DD
=5V
V
DD
=3V
CE0,CE1 pins
V
DD
=5V
I
OH
=-1mA
V
DD
=3V
DATA,FOUT pins
V
DD
=3V
I
OH
=-100mA
DATA,FOUT pins
V
DD
=5V
I
OL
=1mA
V
DD
=3V
DATA,FOUT pins
V
DD
=3V
I
OL
=100
mA
DATA,FOUT pins
V
DD
=5V
I
OL
=1mA
V
DD
=3V
/ AIRQ,/ TIRQ pins
V
O
=GND or V
DD
DATA,/ AIRQ,/ TIRQ pins
(V
DD
=1.6 to 5.5V,Ta=-40 to 85°C )
MIN.
TYP.
MAX.
Unit
-
1.0
2.0
m
A
-
0.5
1.0
m
A
0.8V
DD
-
V
DD
V
0
-
0.2V
DD
V
-0.5
75
150
4.5
2.0
2.9
-
150
300
0.5
300
600
5.0
3.0
3.0
GND+0.5
GND+0.8
GND+0.1
GND+0.25
GND+0.4
-0.5
0.5
mA
kW
kW
V
V
V
V
V
V
V
V
mA
Output voltage 1
Page-3
Aug.1998
5. AC Characteristics
V
DD
=3.0V±10%
MIN.
TYP.
MAX.
1200
600
-
-
600
-
-
300
-
-
400
-
-
600
-
-
100
-
-
50
-
-
50
-
-
0
-
400
-
-
200
-
-
40
35
-
65
( CL=50pF,Ta=-40 to 85
°C
)
V
DD
=5.0V±10%
MIN.
TYP.
MAX.
Unit
600
ns
300
-
-
ns
300
-
-
ns
150
-
-
ns
200
-
-
ns
300
-
-
ns
50
-
-
ns
50
-
-
ns
50
-
-
ns
0
-
200
ns
-
-
100
ns
-
-
20
ns
40
-
60
%
Description
CLK clock cycle
CLK H Pulse Width
CLK L Pulse Width
CE setup time
CE hold time
CE recovery time
CLK hold time
Write DATA in setup time
Write DATA in hold time
Read DATA in delay time
Output disable delay time
rise and fall time
FOUT duty ratio
( 32.768kHz output )
Symbol
t
CLK
t
WH
t
WL
t
CS
t
CH
t
CR
t
CKH
t
DS
t
DH
t
RD
t
RZ
t
RF
Duty
t
CS
t
WL
t
WH
t
CH
t
CKH
CLK
50%
CE
50%
t
CR
Write Mode
t
DS
t
DH
ReadMode
t
RF
t
RF
90%
CLK
50%
CLK
50%
10%
t
RD
90%
DATA
50%
DATA
50%
10%
Hi-Z
t
RZ
CE
50%
CE
t
CS
50%
Page-4
Aug.1998
n
Register Table
Function
Sec
Min
Hour
Week
Day
Month
Year
Minutes Alarm
Hours Alarm
Week Alarm
Day Alarm
FOUT control
Timer interrupt control
Count Down Timer
Control 1
Control 2
bit7
fos
fr
fr
fr
fr
fr
80
AE
AE
AE
AE
FE
TE
128
*
*
bit6
40
40
*
6
*
*
40
40
*
6
*
*
*
64
*
TEST
bit5
bit4
bit3
20
10
8
20
10
8
20
10
8
5
4
3
20
10
8
*
10
8
20
10
8
20
10
8
20
10
8
5
4
3
20
10
8
FD4
FD3
*
TD1
TD0
*
32
16
8
*
TI/TP
AF
STOP RESET HOLD
bit2
4
4
4
2
4
4
4
4
4
2
4
FD2
*
4
TF
*
bit1
2
2
2
1
2
2
2
2
2
1
2
FD1
*
2
AIE
*
bit0
1
1
1
0
1
1
1
1
1
0
1
FD0
*
1
TIE
*
Address
0
1
2
3
4
5
6
7
8
9
A
B
C
D
E
F
1.1 Timekeeping/calendar registers (register 0 to register 6)
·
The data in these registers is BCD format. For example, "0101 1001" represents 59 seconds. In addition, the
"*" mark in the register table means that the register is readable and writable, and can be used as RAM. Time is
kept in the 24-hour format.
·
Writing to a bit marked with an asterisk ("*") is permitted; such bits can be used as RAM. When the alarm and
timer functions are not used, registers 7 to A can be used as 8-bit memory registers, and registers C and D can
be used as 7-bit memory registers.
·
Year register and leap years
A leap year is detected by dividing the two BCD digits of the year register by four; if the remainder is zero, the
year is a leap year. Therefore, leap years can be automatically determined whether the year is numbered
according to the western calendar or the Japanese calendar (year of Heisei).
·
Day of the week
The day of the week register uses 7 bits, from 0 to 6; the meanings of the bits are shown in the table below.
not set more than one bit to "1" at any one time.
bit 6
0
0
0
0
0
0
1
bit 5
0
0
0
0
0
1
0
bit 4
0
0
0
0
1
0
0
bit 3
0
0
0
1
0
0
0
bit 2
0
0
1
0
0
0
0
bit 1
0
1
0
0
0
0
0
bit 0
1
0
0
0
0
0
0
day of week
Sunday
Monday
Tuesday
Wednesday
Thursday
Friday
Saturday
Do
·
fos
( OSC Flag )
This flag uses it for a monitor of battery listing degradation with the binary digit which that oscillation stopped is
set at. Oscillation stopping shows "1", and it is cleared by writing in "0". But fo flag can't write in "0" when
oscillation stopped. And fo can write in "1", but don't write in it. Other binary digit (HOLD,STOP,RESET) doesn't
receive affect even in case of "1".
·
fr
( READ Flag )
It is the binary digit that turn into "1" when CE was input, and carry occurred during "H" for 1 second. The distinction
that carry to a figure rose during (CE input ="H" during readout of register in an indicator by this for 1 second is
possible. When fr was "1", I need to read register in all indicators once again.
Page-5
Aug.1998
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