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Epson RTC-72421 A manual

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Table of contents for the manual

  • Page 1

    M Q 162-0 3 Application Manua l Real Time Clock Module RTC-72421/72423 Model Product Number R T C - 72421 A Q4272421 x 000100 R T C - 72421 B Q4272421 x 000200 R T C - 72423 A Q4272423 x 000600 R T C - 72423 Q4272423 x 000700[...]

  • Page 2

    N O T I C E • 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., w ritten in this material is just for reference. Seiko Epson does not assume any li[...]

  • Page 3

    RTC - 72421 / 72423 CONTENTS  Ov ervi ew ............................................................................................. 1  Block diagram ..................................................................................... 1  Term inal connections .......................................................................... 2 ?[...]

  • Page 4

    RTC - 72421 / 72423 Page - 1 MQ - 162 - 03 4-BIT PARALLEL INTERFACE REAL TIME CLOCK MODULE RTC - 72421 / 72423 • Built-in crystal unit removes need for adjustment and reduces installation costs • M icroprocessor bus compatible ( tW W, t RD = 120 ns ) • Use of C-M OS IC enables low current consumption ( 5 µ A Max ., at V DD = 2.0 V ) • Comp[...]

  • Page 5

    RTC - 72421 / 72423 Page - 2 MQ - 162 - 03  Terminal connections RTC-72421 RTC-72423 1 2 3 4 5 6 7 8 9 18 17 16 15 14 13 12 10 11 STD.P CS 0 ALE A 0 A 1 A 2 A 3 RD GND V DD () V DD ( V DD ) CS 1 D 0 1 2 3 WR D D D 1 2 3 4 5 6 7 8 9 10 11 12 24 23 22 21 20 19 18 17 16 15 13 14 STD.P CS 0 ALE A 0 A 1 A 2 A 3 RD GND N.C. N.C. N.C. V DD () N.C. CS 1[...]

  • Page 6

    RTC - 72421 / 72423 Page - 3 MQ - 162 - 03  Terminal functions Pin No. Signal RTC-72421 RTC-72423 Input/o u tput Function D 0 -D 3 (Data bus) 11 − 14 14 − 16, 19 Bi- directi on Connect these pines to a bi-directional data bus or CP U data bus. Use this bus to read to and write from the internal counter and registers. CS 1 CS 0 RD W R M ode o[...]

  • Page 7

    RTC - 72421 / 72423 Page - 4 MQ - 162 - 03  Characteristics 1. Abso lute ma ximu m ratings Item Sy mbol Condition Specificat ion Unit Supply volt age V DD Ta=+25 ° C − 0.3 to 7.0 V Input volt age V I Ta=+25 ° C GND − 0.3 t o V DD +0.3 V Output volt age V O Ta=+25 ° C GND − 0.3 t o V DD +0.3 V RTC-72421 − 55 to +85 ° C Storage tem per[...]

  • Page 8

    RTC - 72421 / 72423 Page - 5 MQ - 162 - 03  Switching characteristics (AC characteristics) 1. W hen ALE is used W rite mode ( V DD =5 V ± 0.5 V, RTC-72421;Ta= − 10 ° C to +70 ° C, RTC-72423;Ta= − 40 ° C to +85 ° C ) Item Symbol Condition Min. Max. Unit CS1 set -up t i m e t SU (CS1) 1000 Address s et-up time bef ore A LE t SU (A -ALE) 5[...]

  • Page 9

    RTC - 72421 / 72423 Page - 6 MQ - 162 - 03 2. W hen ALE is f ix ed at V DD W rite mode ( V DD =5 V ± 0.5 V, RTC-72421;Ta= − 10 ° C to +70 ° C, RTC-72423;Ta= − 40 ° C to +85 ° C ) Item Symbol Condition Min. Max. Unit CS1 set -up t i m e t SU (CS1) 1000 CS1 hold tim e th(CS1) 1000 Address s et-up time bef ore write t SU (A-W ) 50 Address hol[...]

  • Page 10

    RTC - 72421 / 72423 Page - 7 MQ - 162 - 03  Registers 1. Register table Data Address (Hex) A3 A2 A1 A0 Register name D3 D2 D1 D0 Count (BCD) Remarks 0 0 0 0 0 S1 s8 s4 s2 s1 0 to 9 1-second di g it re g ister 1 0 0 0 1 S10 * s40 s20 s10 0 to 5 10-seconds digit register 2 0 0 1 0 MI1 m i8 mi4 m i2 mi1 0 to 9 1-minute digit register 3 0 0 1 1 MI 1[...]

  • Page 11

    RTC - 72421 / 72423 Page - 8 MQ - 162 - 03 4. Setting the fixed-period pulse output m ode and f ixed-period interrupt m ode Mode MASK ITRPT/ST ND ITRPT/STND STD.P pin Setting of fixed-period output timing Fixed-period pulse output mode 0 0 t1 bit 0 0 1 1 Fixed-period interrupt mode 0 1 Set to 1 when active Set low when active t0 bit 0 1 0 1 Fixed-p[...]

  • Page 12

    RTC - 72421 / 72423 Page - 9 MQ - 162 - 03  Register description 1. Timing r eg isters (1) S1 to Y10 regi s ters These regist ers are 4-bit, posi tive logic regist ers in which the digits of the year, m onth, day, hour, m inute, and s econd are continuous ly w ritten i n B CD code. For example, when(1, 0, 0, 1) has been w ritten t o the bits of [...]

  • Page 13

    RTC - 72421 / 72423 Page - 10 MQ - 162 - 03 2. CD reg ist er (control reg ist er D) (1) HOLD bit (D0) Use the HOLD bit when acc essing the S1 and W regist ers. For details , see "Read/write of S1 t o W regis t ers ". HOLD bit Function HOLD bit 0 The BUSY bit i s alway s 1 (the BU SY status cannot be checked). 1 The BUS Y status can be che[...]

  • Page 14

    RTC - 72421 / 72423 Page - 11 MQ - 162 - 03 IRQ FL AG bit *STD . P pin output 01 0 1 Inte rrupt ge ne ratio n (in sy nchron izati o n wi th co u nt i ncre m e nta ti o n) W riting o f 0 IRQ FLAG b it. The output level s of the STD.P pi n are low (down) and open circuit (up). Note: If the ST D.P pin output rem ains low as set, subsequently generated[...]

  • Page 15

    RTC - 72421 / 72423 Page - 12 MQ - 162 - 03 2.Fixed-period interrupt m ode (ITRPT/STND=1) 1 1 1 0 0 0 0 Nothing is output bec ause the MASK bit is at 1 Interrupt tim ing Reset at the poi nt at which 0 i s wri tten to the I RF FLAG bit No int errupts ar e generated whil e the M ASK bit is at 1 *STD . P pin IRQ FLAG bit MASK bit The output levels of [...]

  • Page 16

    RTC - 72421 / 72423 Page - 13 MQ - 162 - 03 4. CF reg ister (control reg ister F) (1) RESET bi t (D0) W riting 1 to the RESET bit clears the s ub-second bits of t he internal counter down to the 1/256-seconds counter. The reset continues f or as long as the RESET bit is 1. End the reset by writing 0 to the RESET bit. If the level of the CS 1 pin go[...]

  • Page 17

    RTC - 72421 / 72423 Page - 14 MQ - 162 - 03  Using the RTC-72421/RTC-72423 1. Power-on procedure ( init ialization) W hen pow er is turned on, the contents of all regis ters and the output from the S TD.P pin are undefined. Therefore, all the regi ster s mus t be initialized aft er power on. Foll ow the procedure gi ven bel ow for ini t ializati[...]

  • Page 18

    RTC - 72421 / 72423 Page - 15 MQ - 162 - 03 (A)Starting the count START Set the C F regis ter Reg.F T EST 24/12 ST OP RESET Reg.D 30 s ADJ IR Q F LA G HOLD To nex t pr ocess 0 0 0 0 or 1 0*00B T his s etting is not necessar y when the ST D.P pin is not used 0 0 0 or 1 0*00B ← ← ← ← ← ← ← ← ← Set the I RQ F LA G bi t to 0 when fix [...]

  • Page 19

    RTC - 72421 / 72423 Page - 16 MQ - 162 - 03 2. Read/write of S1 to W register s Use one of t he procedures shown below to access registers other t han the control regis ters (CD, CE, and CF) while the RTC is operating. Not e t hat the control regi s ters can be acc es sed regardless of t he status of t he BUSY bit. Read or write when the HOLD bit i[...]

  • Page 20

    RTC - 72421 / 72423 Page - 17 MQ - 162 - 03 4. Using t he CS 1 pin The RTC-72421/RTC-72423 has 2 c hip-select si gnal system s: CS 0 and CS1. Us e CS 0 as chip-sel ect for ordinary bus acces s. CS 1 is not onl y us ed for CPU bus cont rol , it also has t he m ain funct i on of s w itchi ng bet w een standby m ode and operating mode. (1) Functions P[...]

  • Page 21

    RTC - 72421 / 72423 Page - 18 MQ - 162 - 03  Examples of connection to general-purpose microprocessor W hen connecting t he RTC-72421/RTC-72423 to a mic roprocessor, caref ully check t he AC timings of both the RTC and the mic roprocessor. 1. Connection to m ult iplex ed bus type AD3 AD2 AD1 AD0 IO/ M ALE RD WR Decoder A3 A2 A1 A0 D3 D2 D1 D0 CS[...]

  • Page 22

    RTC - 72421 / 72423 Page - 19 MQ - 162 - 03  External dimensions 1. RTC-72421 23.1 Max. 6.3 4.2 Max. 2.54 Min. 0.2 Min. 2.54 0.46 7.62 0 - 15 0.25 1.52 2. RTC-72423 Min. 16.3 Max. 7.9 0.35 1.27 0.1 2.8 Max. 1.0 12.0 0.2 0 - 10 Unless ot herw ise st ated, all units are [mm ]  Marking layout RTC72421 EPSON A 6053C Type Freque ncy tlerance Manuf[...]

  • Page 23

    RTC - 72421 / 72423 Page - 20 MQ - 162 - 03  Reference data [Finding the frequenc y s t ability] 1. Frequency and t em perature charact eri s tics can be approxim ated using the f ol l owing equati ons . ∆ fT = α ( θ T - θ X ) 2 ∆ fT : Frequency deviation i n any tem perature α ( 1 / °C 2 ) : Coeffi c ient of sec ondary t emperature ( ?[...]

  • Page 24

    RTC - 72421 / 72423 Page - 21 MQ - 162 - 03  Application notes 1. Notes on handling This module uses a C -MO S IC to realize low power consumption. Carefully note the follow ing cautions when handling. (1) Static electricity W hile t his module has built- in cir cuitr y designed to pr otect i t against elect rostat ic di scharge, the chip c ould[...]

  • Page 25

    Application Manual AME RIC A EPSON ELECTRONICS AMERICA , INC. HEA DQUA RTER 150 River Oaks Parkw ay , San Jose, CA 95134, U.S.A. Phone: (1)800-228-3964 (Toll free) : (1)408-922-0200 (Main) Fax: (1)408-922-0238 htt p://www. eea.epson.com A tl anta Office 3010 Roy al Blvd. South, Ste. 170, Alpharetta, GA 30005, U.S.A . Phone: (1)877-332-0020 (Toll fr[...]