Real time clock module
4-bit REAL TIME CLOCK MODULE
RTC-72421/72423
•
•
•
•
•
•
Built-in crystal unit allows adjustment-free efficient operation.
ALE input terminal available for 8048, 8051, and 8085 series.
12/24 h clock switchover function and automatic leap year setting.
Interrupt masking.
30 second adjustment function.
Low current consumption and features a backup function.
Actual size
Specifications (characteristics)
Absolute Max. rating
Terminal connection
RTC-72421
Specifications
-0.3 to 7.0
GND -0.3 to VDD+0.3
-55 to +85
Unit
V
Symbol
VDD
VI/O
Condition
Ta=+25 °C
Ta=+25 °C
RTC-72421
RTC-72423
Item
No.
1
2
72421
STD. P
No.
1
2
72423
STD. P
CS0
Power source voltage
Input and output voltage
18 17 16 15 14 13 12 11 10
CS
0
ALE
3
3
NC
A
A
A
0
1
2
4
5
6
7
4
5
6
7
ALE
A0
NC
A1
°C
TSTG
Storage temperature
Soldering condition
-55 to +125
A
3
Under +260 °C within 10 s
(lead part) (package should
be less than +150 °C)
RD
GND
WR
8
9
8
9
NC
RTC-72421
RTC-72423
A
A
2
TSOL
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
3
Twice at under +260
s or under +230 C within 3 min.
°C within 10
D
D
D
D
3
2
1
0
RD
GND
WR
°
RTC-72423
D
D
D
3
2
1
Operating range
24 23 22 21 20 19 18 17 16 15 14 13
CS
1
Unit
V
(
(
)
)
Item
Symbol
Specifications
4.5 to 5.5
-10 to 70
VDD
VDD
Condition
NC
NC
Operating voltage
VDD
TOPR
VDH
VDD
D
0
RTC-72421
RTC-72423
°C
V
Operating temperature
CS1
-40 to 85
NC
VDD
VDD
VDD
(
(
)
)
Data holding voltage
CSI data holding time
Operation restoring time
2.0 to 5.5
tCDR
tR
1
2 3 4 5 6 7 8 9 10 11 12
Refer to the data
holding timing
µs
2.0 Min.
(VDD) and VDD are to have the same level of voltage. Do not connect it to any external terminals.
NC is not connected internally.
Frequency characteristics and current consumption
characteristics
(Unit: mm)
External dimensions
Symbol
Condition
Specifications Unit
Item
RTC-72421
10
50
20
72421 A
23.1 Max.
Ta=+25 °C 72421 B
VDD=5 V
72423 A
∆f/fo
Frequency tolerance
-6
x 10
RTC72421 A
EPSON 5053C
50
72423
Frequency temperature
characteristics
-10 °C to +70 °C
7.62
+10/-120
5 Max.
(+25 °C reference temperature)
VDD=5 V, Ta=+25 °C,
first year
-6
x 10 /year
fa
Aging
0.25
Three drops on a
hard board from 750 mm
90° to
105°
-6
2
x 10
Shock resistance
S.R.
10 Max.
or 29400 m/s x 0.3 ms x
1/2 sine wave x 3 directions
2.54
0.65 Max.
CS1=0 V VDD=5 V
IDD1
IDD2
10 Max.
5 Max.
µA
Exclude input/
Current consumption
VDD=2 V
output current
DC characteristics
RTC-72423
Applicable
terminal
Item
Symbol Condition Min. Typ. Max. Unit
16.3 Max.
All inputs
other than
“H” input voltage (1)
“L” input voltage (1)
Input leak current (1)
Input leak current (2)
“L” output voltage (1)
“H” output voltage
“L” output voltage (2)
Off leak current
VIH1
VIL1
ILK1
2.2
—
0.8
1
—
V
CS
Input other
1
than D0 to D3
V1=VDD/0 V
IOL=2.5 mA
µA
—
2.4
—
ILK2
10
0.4
—
0.4
10
—
RTC72423 A
EPSON 6150
D0 to D3
STD.P
VOL1
VOH
I
OH=-400 µA
V
IOL=2.5 mA
VOL2
IOFFLK
V
1
=VDD/0 V
Input
µA
pF
Input other
than D0 to D3
10
20
0° to
10°
Input capacity
C1
0.05 Min.
1.0
frequency 1 MHz
D0 to D3
CS1
1.27
0.35
—
2.8 Max.
“H” input voltage (2)
“L” input voltage (2)
4/5 VDD
VIH2
VIL2
VDD=2to 5.5 V
—
V
—
1/5 VDD
77