Epson RTC-72421 A, RTC-72421 B, RTC-72423, RTC-72423 A Notes, When ALE is used, Timing registers, Using the CS1 pin, Notes on handling, Notes on packaging, (AC characteristics), When ALE is fixed at VDD

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 VDD .........................................................................................	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 CS1 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