MQ152-05
Application
Manua
l
Real Time Clock Module
RTC-62421
/
62423
Model
RTC-62421A
RTC-62421B
RTC-62423A
RTC-62423
Product Number
Q42624211000200
Q42624211000300
Q42624231000200
Q42624231000300
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NOTICE
• The material is subject to change without notice.
• Any part of this material may not be reproduced or duplicated in any form or any means without the
written permission of Seiko Epson.
• The information, applied circuit, program, using way etc., written in this material is just for reference.
Seiko Epson does not assume any liability for the occurrence of infringing any patent or copyright of third
party. This material does not authorize the licence for any patent or intellectual property rights.
• Any product described in this material may contain technology or the subject relating to strategic
products under the control of the Foreign Exchange and Foreign Trade Law of Japan and may require an
export licence from the Ministry of International Trade and industry or other approval from another
government agency.
• The products (except for some product for automotive applications) listed up on this material are designed
to be used with ordinary electronic equipment (OA equipment, AV equipment, communications equipment,
measuring instruments etc). Seiko Epson does not assume any liability for the case using the products with
the appoication required high reliability or safety extremely (such as aerospace equipment etc).
When intending to use any our product with automotive application and the other application than
ordinary electronic equipments as above, please contact our sales representatives in advance.
RTC - 62421 / 62423
CONTENTS
!
Overview
....................................................................................................................... 1
!
Block diagram
............................................................................................................. 1
!
Pin connections
.......................................................................................................... 1
!
Pin functions
................................................................................................................ 2
!
Characteristics
............................................................................................................ 3
1. Absolute maximum ratings
..............................................................................................................3
2. Operating conditions
.........................................................................................................................3
3. Frequency characteristics and current consumption characteristics
.................................3
4. Electrical characteristics (DC characteristics)
...........................................................................3
!
Switching characteristics
(AC characteristics) ........................................................ 4
1. When ALE is used
.............................................................................................................................4
2. When ALE is fixed at V
DD ...............................................................................................................5
!
Registers
....................................................................................................................... 6
1. Register table
.......................................................................................................................................6
2. Notes
......................................................................................................................................................6
3. Functions of register bits (overview)
............................................................................................7
4. Setting the fixed-period pulse output mode and interrupt mode
.........................................7
5. Resetting the fixed-period pulse output mode and interrupt mode
....................................7
!
Register description
.................................................................................................. 8
1. Timing registers
..................................................................................................................................8
2. C
D
register (control register D)
......................................................................................................9
3. C
E
register (control register E)
.....................................................................................................10
4. C
F
register (control register F)
.....................................................................................................12
!
Using the RTC-62421 /RTC-62423
.................................................................. 13
1. Power-on procedure (initialization)
.............................................................................................13
2. Read /write of S1 to W registers
.................................................................................................14
3. Write to 30-second ADJ bit
...........................................................................................................15
4. Switch over between 24- and 12-hour clock modes
.............................................................16
5. Using the CS1 pin
............................................................................................................................16
!
Power supply circuit example
............................................................................. 17
!
Examples of connection to general-purpose microprocessor
................. 17
1.
2.
3.
Connection to multiplexed bus type .................................................................................................17
Connection to Z80 or compatible CPU.............................................................................................17
Connection to 68-series MPU ..........................................................................................................17
!
External dimensions
............................................................................................... 18
!
Marking layout
.......................................................................................................... 18
!
Reference data
......................................................................................................... 19
(1) Example of frequency and temperature characteristics
...................................................................................19
(2) Frequency voltage characteristics (typical)
....................................................................................................19
(3) Current consumption voltage characteristics (typical)
......................................................................................19
!
Application notes
..................................................................................................... 20
1. Notes on handling
............................................................................................................................20
2. Notes on packaging
.........................................................................................................................20
RTC - 62421 / 62423
4-Bit Parallel Interface Real Time Clock Module
RTC-62421 /RTC-62423
•
Built-in quartz crystal removes need for adjustment and reduces installation costs
•
Microprocessor bus compatible(Tww, tRD = 120 ns)
•
Use of C-MOS IC enables low current consumption (1.8
µA
Max. at V
DD
= 2.0 V)
•
Compatibility with Intel CPU bus
•
Address latch enable (ALE) pin compatible with multiplex bus CPUs
•
Time (hours, minutes, seconds) and calendar (year, month, day) counter
•
24-hour/12-hour switch over and automatic leap-year correction functions
•
Fixed-period interrupt function
•
30-seconds correction (adjustment) function
•
Stop, start, and reset functions
•
Battery back-up function
•
Same mounting conditions as general-purpose SMD ICs possible (RTC-62423)
*
Pins and functions compatible with the MSM6242B series
!
Overview
The RTC-62421 /RTC-62423 module is a real time clock that can be connected directly to a microprocessor's bus. Its built-in quartz
crystal enables highly accurate timekeeping with no physical access required for adjustment and, since there is no need to connect
external components, mounting and other costs can be reduced.
In addition to its time and calendar functions, the RTC-62421 /RTC-62423 enables the use of 30-seconds correction and fixed-period
interrupt functions.
The RTC-62421 /RTC-62423 module is ideally suited for applications requiring timing management, such as personal computers,
dedicated word processors, fax machines, multi-function telephones, and sequencers.
!
Block diagram
RTC-62421 /62423
OSC
D3
D2
D1
D0
Counter
Gate
RESET STOP
bit
bit
30 sec ADJ
bit
S1
Gate
S10
HOLD
bit
BUSY
bit
24/12
bit
WR
RD
MI1
MI10
H1
H10
W
A3
A2
A1
A0
CS0
ALE
CS1
S1 to CF
Latch
Decoder
D1
D10
MO1 MO10
Y1
Y10
Output Selector
64 Hz
1 Second carry
1 Minute carry
1 Hour carry
V
DD
STD.P
CD
CE
CF
!
Pin connections
RTC-62421
STD.P 1
CS
0
ALE
A
0
A
1
A
2
A
3
RD
GND
2
3
4
5
6
7
8
9
18
V
DD
STD.P 1
CS
0
RTC-62423
24 V
DD
23 (V
DD
)
22 (V
DD
)
21 N.C
20 CS
1
19 D
0
18 N.C
17 N.C
16 D
1
15 D
2
14 D
3
13 WR
2
3
4
5
6
7
8
9
10
11
12
17 ( V
DD
)
16 ( V
DD
)
15
14
13
12
11
10
CS
1
D
0
D
1
D
2
D
3
WR
N.C.
ALE
A
0
N.C.
A
1
N.C.
A
2
A
3
RD
GND
The (V
DD
) pins are at the same electrical level as V
DD
. Do not connect these pins externally.
The N.C. pins are not connected internally. Ground them in order to prevent noise.
Page - 1
MQ152-05
RTC - 62421 / 62423
!
Pin functions
Signal
Pin No
RTC-62421
RTC-62423
Input/
Output
Function
Connect these pins to a bi-directional data bus or CPU data bus. Use this bus to
read to and write from the internal counter and registers.
CS1
D0 -D3
(Data bus)
14,13,12,11
19,16,15,14 Bi-direction
H
H
H
L
H
CS0
L
L
L
H
RD
L
H
L
WR
H
L
L
Mode of D0 to D3
Output mode (read mode)
Input mode (write mode)
Do not use
High impedance (back-up mode)
High impedance (RTC not selected)
H or L
H or L
A0 -A3
(Address bus)
4,5,6,7
5,7,9,10
Input
Address input pins used for connection to CPU addresses, etc. Used to select the
RTC's internal counter and registers (address selection). When the RTC is
connected to a multiplexed-bus type of CPU, these pins can also be used in
combination with the ALE described below.
Reads in address data and
the address data and
CS0
CS0
state for internal latching. When the ALE is high,
state is read into the RTC. When the (through-mode)
CS0
ALE falls, the address data and
ALE
(Address Latch
Enable)
3
4
Input
data and
CS0
state at that point are held. The held address
status are maintained while the ALE is low.
ALE
Address data and CS0 status
Read into the RTC to set address data
H
L
Held in the RTC (latched at the trailing edge of the ALE)
If the RTC is connected to a CPU that does not have an ALE pin and thus there is no
need to use this ALE pin, fix it to V
DD
.
Writes the data on D0 to D3 into the register of the address specified by A0 to A3, at
WR
10
13
Input
the leading edge of
Make sure that
RD
WR
.
WR
(WRite)
and
are never low at the same time.
Outputs data to D0 to D3 from the register at the address specified by A0 to A3,
RD
8
11
Input
while
RD
is low.
RD
(ReaD)
Make sure that
and
CS0
WR
are never low at the same time.
When CS1 is high and
and write are enabled.
is low, the RTC's chip-select function is valid and read
When the RTC is connected to a multiplexed-bus type of CPU,
CS1,
CS0
(Chip Select)
15, 2
20, 2
Input
CS0
requires the
operation of the ALE (see the description of the ALE).
Use CS1 connected to a power voltage detection circuit. When CS1 is high, the RTC
is enabled; when it is low, the RTC is on standby.
When CS1 goes low, the HOLD and RESET bits in the RTC registers are cleared to
0.
This is an N-channel open drain output pin.
Depending on the setting of the C
E
register, a fixed-period interrupt signal and a
pulse signal are output.
The output from this pin cannot be inhibited by the CS1 and
CS0
signals.
Use a load voltage that is less than or equal to V
DD
. If not using this pin, keep it
open-circuit.
An example of STD.P connection is shown below.
+5 V or V
DD
RTC
STD.P
(STanDard Pulse)
1
1
Output
Protective
diode
At least 2.2 kΩ
STD.P
V
DD
GND
(V
DD
)
N.C.
18
9
16, 17
-
24
12
22, 23
3, 6, 8, 17,
18, 21
If the STD.P output is not to be used during standby operation, connecting the pull-
up resistor to +5 V provides a reduction in current consumption. If the STD.P output
is to be used even during standby, connect the pull-up resistor to the RTC's V
DD
. In
this case, the current consumption will be increased by the amount of current flowing
through the pull-up resistor.
Connect this pin to the power source. Supply 5 V ±10 % to this pin during normal
operation; at least 2 V during battery back-up operation.
Connect this pin to ground.
These pins are connected internally to V
DD
. Leave them open circuit.
These pins are not connected internally. Ground them.
Page - 2
MQ152-05
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