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RTC - 72421 / 72423
CONTENTS
Overview............................................................................................. 1
Block diagram ..................................................................................... 1
Terminal connections.......................................................................... 2
Terminal functions............................................................................... 3
Characteristics .................................................................................... 4
1. Absolute maximum ratings........................................................................................ 4
2. Recommended operating conditions......................................................................... 4
3. Frequency characteristics and current consumption characteristics.......................... 4
4. Electrical characteristics ( DC characteristics ) ......................................................... 4
Switching characteristics
(AC characteristics)
........................................... 5
1. When ALE is used ....................................................................................................5
2. When ALE is fixed at V
DD
......................................................................................... 6
Registers............................................................................................. 7
1. Register table............................................................................................................ 7
2. Notes ........................................................................................................................7
3. Functions of register bits (overview).......................................................................... 7
4. Setting the fixed-period pulse output mode and fixed-period interrupt mode............. 8
5. Resetting the fixed-period pulse output mode and fixed-period interrupt mode......... 8
Register description ............................................................................ 9
1. Timing registers ........................................................................................................9
2. CD register (control register D) ............................................................................... 10
3. CE register (control register E)................................................................................ 11
4. CF register (control register F)................................................................................13
Using the RTC-72421/RTC-72423 .....................................................14
1. Power-on procedure (initialization)..........................................................................14
2. Read/write of S1 to W registers ..............................................................................16
3. Write to 30-second ADJ bit .....................................................................................16
4. Using the CS
1
pin ................................................................................................... 17
Power supply circuit example.............................................................17
Examples of connection to general-purpose microprocessor.............18
External dimensions...........................................................................19
Marking layout....................................................................................19
Reference data ..................................................................................20
Application notes................................................................................21
1. Notes on handling...................................................................................................21
2. Notes on packaging ................................................................................................21