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CONTENTS

■ Using the RTC-72421/RTC-72423 ----------------------------------------------------------------16

1. Power-on procedure (initialization) ------------------------------------------------------------------------------------16

2. Read/write of S1 to W registers-----------------------------------------------------------------------------------------18

3. Write to 30-second ADJ bit ----------------------------------------------------------------------------------------------18

4. Using the CS1 pin ----------------------------------------------------------------------------------------------------------19

(1) Functions-----------------------------------------------------------------------------------------------------------------19

(2) Timing---------------------------------------------------------------------------------------------------------------------19

(3) Note-----------------------------------------------------------------------------------------------------------------------19

■ Power supply circuit example-----------------------------------------------------------------------19

■ Examples of connection to general-purpose microprocessor ------------------------------20

1. Connection to multiplexed bus type ------------------------------------------------------------------------------------20

2. Connection to Z80 or compatible CPU --------------------------------------------------------------------------------20

3. Connection to 68-series MPU--------------------------------------------------------------------------------------------20

■ Reference data -----------------------------------------------------------------------------------------21

1. Frequency temperature characteristics (typical) --------------------------------------------------------------------21

2. Frequency voltage characteristics (typical)---------------------------------------------------------------------------21

3. Current consumption voltage characteristics (typical) -------------------------------------------------------------21

■ External dimensions-----------------------------------------------------------------------------------22

1. RTC-72421 -------------------------------------------------------------------------------------------------------------------22

2. RTC-72423 -------------------------------------------------------------------------------------------------------------------22

■ Marking layout ------------------------------------------------------------------------------------------22

■ Application notes---------------------------------------------------------------------------------------23

1. Notes on handling----------------------------------------------------------------------------------------------------------23

(1) Static electricity ---------------------------------------------------------------------------------------------------------22

(2) Noise ----------------------------------------------------------------------------------------------------------------------22

(3) Voltage levels of input pins ------------------------------------------------------------------------------------------22

(4) Treatment of unused input pins-------------------------------------------------------------------------------------22

2. Notes on mounting---------------------------------------------------------------------------------------------------------23

(1) Soldering temperature conditions----------------------------------------------------------------------------------23

(2) Mounting equipment---------------------------------------------------------------------------------------------------24

(3) Ultrasonic cleaning-----------------------------------------------------------------------------------------------------24

(4) Mounting orientation---------------------------------------------------------------------------------------------------24

(5) Leakage between pins------------------------------------------------------------------------------------------------24

Epson RTC-72421 User Manual

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