Datasheet RS5C316A, RS5C316B Datasheet (RICOH)

ULTRA-COMPA CT SERIAL

ALARM REAL-TIME CLOCK ICs

RS5C316A/B

ELECTRONIC DEVICES DIVISION

NO.EA-035-9908

APPLICATION MANUAL

NOTICE

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the products, please refer to Ricoh sales representatives for the latest information thereon.

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4. The technical information described in this application manual shows typical characteristics of and example
application circuits for the products. The release of such information is not to be construed as a warranty of or a
grant of license under Ricoh's or any third party's intellectual property rights or any other rights.

5. The products listed in this document are intended and designed for use as general electronic components in
standard applications (office equipment, computer equipment, measuring instruments, consumer electronic
products, amusement equipment etc.). Those customers intending to use a product in an application requiring
extreme quality and reliability, for example, in a highly specific application where the failure or misoperation of
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system etc.) should first contact us.

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8. Please contact Ricoh sales representatives should you have any questions or comments concerning the prod­ucts or the technical information.

June 1995

OUTLINE

......................................................................................................

1

FEATURES

....................................................................................................

1

BLOCK DIAGRAM

.........................................................................................

2

APPLICATIONS

.............................................................................................

2

PIN CONFIGURATION

...................................................................................

2

PIN DESCRIPTIONS

......................................................................................

3

ABSOLUTE MAXIMUM RATINGS

...................................................................

4

RECOMMENDED OPERATING CONDITIONS

.................................................

4

DC CHARACTERISTICS

................................................................................

5

AC CHARACTERISTICS

................................................................................

5

TIMING CHARTS

...........................................................................................

6

FUNCTIONAL DESCRIPTIONS

......................................................................

7

1. Addressing

.................................................................................................

7

2. Registers

...................................................................................................

8

3. Counters

..................................................................................................

13

USAGES

......................................................................................................

15

1. Read Data (For the RS5C316A)

......................................................................

15

2. Write Data (For the RS5C316A)

.......................................................................

16

3. Read Data (For the RS5C316B)

......................................................................

17

4. Write Data (For the RS5C316B)

.......................................................................

18

5. CE Pin

....................................................................................................

19

6. Configuration of Oscillating Circuit

....................................................................

20

7. Oscillator Halt Sensing

.................................................................................

21

8. Typical Power Supply Circuit

...........................................................................

22

9. Oscillation Frequency Adjustment

.....................................................................

22

10. Interrupt Operation

.....................................................................................

24

RS5C316A/B

APPLICATION MANUAL

CONTENTS

11. Typical Application

.....................................................................................

26

12. Typical Characteristic Measurements

...............................................................

27

13. Typical Software-based Operations

.................................................................

29

PACKAGE DIMENSIONS

..............................................................................

33

TAPING SPECIFICATION

..............................................................................

33

URTRA-COMPACT SERIAL ALARM REAL

TIME CLOCK ICs

1

RS5C316A/B

OUTLINE

The RS5C316A/B are CMOS type real-time clock ICs which are connected to the CPU via three signal lines and
capable of serial transmission of clock and calendar data to the CPU.
The RS5C316A/B can generate various periodic interrupt clock pulses lasting for long period (one month), further
alarm interrupt can be made by days of the week, hours, and minutes. Driving an oscillation circuit at constant volt­age, the circuit undergoes few voltage fluctuations and consequently realizes low current consumption (0.6µA at
3V). It also provides an oscillator halt sensing function for application to data validity at power-on and other occa­sions. Integrated into an ultra compact and ultra thin 8pin SSOP (0.65mm pitch), the RS5C316A/B are the optimum
choice for equipment requiring small size and low power consumption.
The RS5C316A and the RS5C316B reads/writes data at falling and rising edge of serial clock respectively.

• Time keeping voltage 1.6V to 6.0V

• Lowest supply current 0.6µA TYP. (1.5µA MAX.) at 3V

• Connection to the CPU via only three pins: CE, SCLK/SCLK and SIO for addressing and data read/write

• A clock counter (counting hours, minutes, and seconds) and a calendar counter (counting leap years, years,

months, days, and days of the week) in BCD code

• Periodic interrupt pulses to the CPU with cycles ranging from one month to 1/1024Hz, with interrupt flags and

interrupt halt

• Alarm interrupt (days of the week, hours, minutes)

• Oscillator halt sensing to judge internal data validity

• Second digit adjustment by ±30 seconds

• 12-hour or 24-hour time display selectable

• Automatic leap year recognition up to the year 2099

• CMOS logic

• Package: 8pin SSOP (0.65mm pitch)

FEATURES

APPLICATIONS

• Communication equipment (Multi-function telephone, portable telephone, PHS, pager)

• Business machines (Facsimile, portable facsimile)

• Personal computer (Desktop type, notebook type, word processor, PDA, electronic notebook, TV games)

• Audio visual equipment (Portable audio equipment, video camera, camera, digital camera, remote control equip­ment)

• Home use (Rice cooker, microwave range)

PIN CONFIGURATION

• 8pin SSOP (0.65mm pitch)

CE

1

SCLK

2

SIO

3

VSS

VDD

OSCIN
OSCOUT

RS5C316A RS5C316B

INTR

4

8

7
6
5

CE

1

SCLK

2

SIO

3

VSS

VDD

OSCIN
OSCOUT

INTR

4

8

7
6
5

RS5C316A/B

2

BLOCK DIAGRAM

OSC DIV

ADDRESS
DECODER

ADDRESS
REGISTER

TIME COUNTER

(SEC,MIN,HOUR,WEEK,DAY,MONTH,YEAR)

INTERRUPT

CONTROL

SHIFT REGISTER

I/O

CONTROL

OSC
DETECT

OSCIN

OSCOUT

ALARM REGISTER
(WEEK,MIN,HOUR)

COMPARATOR

SIO

SCLK/SCLK*

CE

INTR

*

) RS5C316A: SCLK RS5C316B: SCLK

RS5C316A/B

3

Pin No.

1

2

3

5

7
6

8
4

PIN DESCRIPTIONS

Symbol

CE

SCLK

(A type)

SCLK

(B type)

SIO

INTR

OSCIN

OSCOUT

VDD

VSS

Name

Chip enable input

Shift clock input

Serial input/output

Interrupt output

Oscillator circuit
input/output

Positive/Negative
power supply input

Description

The CE pin is used to interface the CPU and is accessible when held at the high
level. This pin is connected to a pull-down resistor. It should be switched to the
low level or opened when not accessed or when powering off the system. Holding
the CE pin high for more than 2.5 seconds forces 1Hz interrupt pulses to be output
from the INTR pin for oscillation frequency measurement. (No “1Hz pulse” is out­put for less than 1.5 seconds.)

This pin is used to input shift clock pulses to synchronize data input to, and output
from, the SIO pin. SCLK and SCLK are for writing data at falling and rising edge of
clock pulses respectively and also reading data at rising and falling edge of clock
pulses respectively.

The SIO pin inputs and outputs written or read data in synchronization with shift
clock pulses from the SCLK/SCLK pin. The SIO pin causes high impedance when
CE pin is held at the low level (CMOS input/output). After the CE pin is switched
to the high level and the control bits and the address bits are input from the SIO,
the SIO pin performs serial input and output operations.

The INTR pin outputs periodic interrupt pulses and alarm interrupt to the CPU.
This pin functions as an Nch open drain output even when the CE pin is held at the
low level.

These pins configure an oscillator circuit by connecting a 32.768kHz crystal oscilla­tor between the OSCIN and OSCOUT pins and by connecting a capacitor between
the OSCIN and Vss pins. (Any other oscillator circuit components are built into
the RS5C316A/B.)

The VDD pin and V

SS pin are connected to the positive power supply and to the

ground level respectively.

RS5C316A/B

4

ABSOLUTE MAXIMUM RATINGS

ABSOLUTE MAXIMUM RATINGS

(VSS=0V)

Symbol Item Conditions Ratings Unit

VDD Supply voltage –0.3 to +7.0 V

VI Input voltage –0.3 to VDD+0.3 V

VO1 Output voltage 1 SIO –0.3 to VDD+0.3 V

VO2 Output voltage 2 INTR –0.3 to +12 V

PD Power dissipation Topt=25°C 300 mW

Topt Operating temperature –40 to +85 ˚C

Tstg Storage temperature –55 to +125 ˚C

Absolute Maximum ratings are threshold limit values that must not be exceeded even for an instant under
any conditions. Moreover, such values for any two items must not be reached simultaneously. Operation
above these absolute maximum ratings may cause degradation or permanent damage to the device. These
are stress ratings only and do not necessarily imply functional operation below these limits.

RECOMMENDED OPERATING CONDITIONS

(VSS=0V, Topt=–40 to +85˚C)

Symbol Item Conditions MIN. TYP. MAX. Unit

VDD Supply voltage 2.5 6.0 V

VCLK Time keeping voltage 1.6 6.0 V

fXT Oscillation frequency 32.768 kHz

CG External oscillation capacitance CL value of crystal=6 to 8pF 5 10 24 pF

V

PUP Pull-up voltage INTR 10 V

RS5C316A/B

5

Symbol Item Pin name Conditions MIN. TYP. MAX. Unit

VIH “H” input voltage CE, SCLK/SCLK, SIO 0.8VDD VDD V

VIL “L” input voltage CE, SCLK/SCLK, SIO 0 0.2VDD V

IOH “H” output current SIO VOH=VDD –0.5V –0.5 mA

IOL1

“L” output current

SIO V

OL1=0.5V 0.5

mA

IOL2 INTR VOL2=0.4V 1
RDN Pull-down resistance CE 45 150 450 kΩ

IILK Input leakage current SCLK/SCLK VI=VDD or VSS –1 1 µA

IOZ1 Output off-state SIO VO=VDD or VSS –2 2

µA

IOZ2 leakage current INTR VO=10V –5 5

I

DD1 Standby current 1 VDD

VDD=3V

0.6 1.5 µA

Input/Output: open

I

DD2 Standby current 2 VDD

VDD=6V

0.8 2.0 µA

Input/Output: open

C

D

Internal oscillation

OSCOUT 10 pF

capacitance

DC CHARACTERISTICS

Unless otherwise specified: VSS=0V, VDD=3V, Topt=–40 to +85˚C, Oscillation frequency=32.768kHz,(CL=6pF, R1=30kΩ), CG=10pF

AC CHARACTERISTICS

(VSS=0V, Topt=–40 to +85˚C, CL=50pF)

Symbol Item

V

DD≥4.5V VDD≥4.0V VDD≥2.5V

Unit

MIN. MAX. MIN. MAX. MIN. MAX.

tCES CE set-up time 175 200 400 ns

tCEH CE hold time 175 200 400 ns

tCR CE inactive time 350 400 800 ns

tSCK SCLK clock cycle time 350 400 800 ns

tCKH

SCLK high time 175 200 400 ns

tCKL SCLK low time 175 200 400 ns
tCKS SCLK to CE set-up time 60 80 120 ns

tRE

Data output start time (from rising

120 135 300 ns

of SCLK) (from falling of SCLK)

tRR

Data output delay time (from rising

120 135 300 ns

of SCLK) (from falling of SCLK)

tRZ Output floating time 120 135 300 ns
tDS Input data set-up time 50 60 120 ns
tDH Input data hold time 50 50 80 ns

RS5C316A/B

6

tSCKtCES

tCKS

tCEH

tCR

tRE

tRZ

tCKHtCKL

tRR

Read Data

Write Data

t

DS tDH

CE

SCLK

SIORead cycle

Write cycle

SIO

tSCKtCES

tCKS

tCEH

tCR

tRE

tRZ

tCKHtCKL

tRR

Read Data

Write Data

t

DS tDH

CE

SCLK

SIORead cycle

Write cycle

SIO

Input/Output conditions: VIH=0.8×VDD, VIL=0.2×VDD, VOH=0.8×VDD, VOL=0.2×VDD

• RS5C316A

• RS5C316B

TIMING CHARTS

*

) Any SCLK/SCLK state is allowed in the hatched area.

RS5C316A/B

7

FUNCTIONAL DESCRIPTIONS

1. Addressing

Address

Registers

Data *

1

A3 A2 A1 A0

D3 D2 D1 D0

0 0 0 0 0

1-second counter (BANK=0) S

8 S4 S2 S1

Day of the week alarm register 1 (BANK=1) AW3 AW2 AW1 AW0

1 0 0 0 1

10-second counter (BANK=0) —*

2

S40 S20 S10

Day of the week alarm register 2 (BANK=1) ALC AW6 AW5 AW4

2 0 0 1 0

1-minute counter (BANK=0) M

8 M4 M2 M1

1-minute alarm register (BANK=1) AM8 AM4 AM2 AM1

3 0 0 1 1

10-minute counter (BANK=0) — M

40 M20 M10

10-minute alarm register (BANK=1) — AM40 AM20 AM10

4 0 1 0 0

1-hour counter (BANK=0) H

8 H4 H2 H1

1-hour alarm register (BANK=1) AH8 AH4 AH2 AH1

5 0 1 0 1

10-hour counter (BANK=0) — — P/A, H

20 H10

10-hour alarm register (BANK=1) ALE — AP/A, AH20 AH10

6 0 1 1 0 Day of the week counter (BANK=0) — W4 W2 W1

7 0 1 1 1 Interrupt cycle register (BANK=0, 1) CT3 CT2 CT1 CT0

8 1 0 0 0 1-day counter (BANK=0) D8 D4 D2 D1

9 1 0 0 1 10-day counter (BANK=0) — — D20 D10

A 1 0 1 0 1-month counter (BANK=0) MO8 MO4 MO2 MO1

B 1 0 1 1 10-month counter (BANK=0) — — — MO10

C 1 1 0 0 1-year counter (BANK=0) Y8 Y4 Y2 Y1

D 1 1 0 1 10-year counter (BANK=0) Y80 Y40 Y20 Y10

E 1 1 1 0 Control register 1 (BANK=0, 1) CTFG ALFG

WTEN

*

6

/XSTP

*

4

ADJ/BSY *

3

F 1 1 1 1 Control register 2 (BANK=0, 1) 12/24 NOP BANK *5TEST *

6

*

1) All the listed data can be read and written.

*

2) The “—” mark indicates data which can be read only and set to “0” when read.

*

3) The ADJ/BSY bit of the control register is set to ADJ for write operation and BSY for read operation.

*

4) The WTEN/XSTP bit of the control register is set to WTEN for write operation and XSTP for read operation.

*

5) The clock/calendar counter and the alarm register can be selected when the BANK=0 and BANK=1 respectively. To designate the BANK is unnec­essary for interrupt cycle register and control register 1/2.

*

6) The WTEN bit and TEST bit are set to “1” when CE is “L”.

RS5C316A/B

8

2. Registers

2.1 Control Register 1 (at Eh)

D3 D2 D1 D0

CTFG

ALFG XSTP BSY

CTFG ALFG WTEN ADJ

(For write operation)

(For read operation)

±30-second Adjustment Bit

ADJ

Description

0
1

Ordinary operation
Second digit adjustment

BSY

Description

0
1

Ordinary operation
Second digit carry or adjustment

Clock/Counter Busy-state Indication Bit

WTEN

Description

0
1

Disabling of 1-second digit carry for clock counter
Enabling of 1-second digit carry for clock counter

Clock Counter Enable/Disable Setting Bit

XSTP

Description

0
1

Ordinary oscillation
Oscillator halt sensing

Oscillator Halt Sensing Bit

ALFG

Description

0
1

Unmatched alarm register with clock counter
Matched alarm register with clock counter

Alarm Flag Bit

CTFG

Description

0
1

INTR=OFF enabling of write operation when CT

3 bit is set to 1

INTR=L enabling of write operation when CT

3 bit is set to 1

Interrupt Flag Bit

2.1-1 (ADJ)

The following operations are performed by setting the ADJ bit to 1.
After this bit is set to 1, the BSY bit is set to 1 for the maximum duration of 122.1µs.
If the WTEN bit is 0, these adjustment operations are started after the WTEN bit is set to 1.

1) For second digits ranging from “00” to “29” seconds:

Time counters smaller than seconds are reset and second digits are set to “00”.

2) For second digits ranging from “30” to “59” seconds:

Time counters smaller than seconds are reset and second digits are set to “00”. Minute digits are incremented by 1.

RS5C316A/B

9

2.1-2 (BSY)

When the BSY bit is 1, the clock and calendar counter are being updated. Consequently, write operation should
be performed for the counters when the BSY bit is 0. Meanwhile, read operation is normally performed for the
counters when the BSY bit is 0, but can be performed without checking the BSY bit as long as appropriate software
is provided for preventing read errors. (Refer to 13. Typical Software-based Operations.) The BSY bit is set to 1 in
the following three cases:

2.1-3 (WTEN)

The WTEN bit should be set to 0 to check that the BSY bit is 0 when performing read and write operations for
the clock and calendar counters. For read operation, the WTEN bit may be left as 1 without checking the BSY bit as
long as appropriate measures such as read repetition are provided for preventing read errors. The WTEN bit
should be set to 1 after completing read and write operations, or will automatically be set to 1 by switching the CE
pin to the low level. If 1-second digit carry occurs when the WTEN bit is 0, a second digit increment by 1 occurs
when the WTEN bit is set to 1. There may be a possibility causing a time delay when it takes 1/1024 second or
more to set WTEN bit from 0 to 1, Read data in state of WTEN=1 in such a case. (Refer to the item 13.3)

2.1-4 (XSTP)

The XSTP bit senses the oscillator halt. When the CE pin is held at the low level, the XSTP bit is set to 1 once
the crystal oscillator is stopped after initial power-on or supply voltage drop and left to be 1 after it is restarted.
When the CE pin is held at the high level, the XSTP bit is left as it was when the CE pin was held at the low level
without checking oscillation stop. As such, the XSTP bit can be used to validate clock and calendar count data after
power-on or supply voltage drop. The XSTP bit is set to 0 when any data is written to the control register 1 (at Eh)
with ordinary oscillation.

2.1-5 (ALFG)

The ALFG bit can be set to 1 when the ALE bit set to 1 with alarm interruption (INTR=L).

MAX.122.1 µs

Setting of the

ADJ bit to 1

Completion of second

digit adjustment

(I) Adjustment of second digits
by ±30 second

(II) Second digits increment by 1
(Subject to 1-sec digit carry when
the WTEN bit is switched from 0 to 1)

(III) Ordinary 1-sec digit carry

MAX.91.6 µs

Setting of the

WTEN bit to 1

End of second digit

increment by 1

91.6 µs

End of second digit carry pulse

Matched alarm

register

Matched alarm

register

ALFG is written to 0 Matched alarm

register

ALFG

INTR

RS5C316A/B

10

2.1-6 (CTFG)

The CTFG bit is set to 1 when interrupt pulses are output from the INTR pin held at the low level. There are two
interrupt modes selectable: the pulse mode (when the CT3 bit is set to 0) and the level mode (when the CT3 bit is set
to 1). The CTFG bit can be set only when the CT

3 is set to 1. Setting the CTFG bit to 1 switches the INTR pin to the

low level while setting the CTFG bit to 0 turns off the INTR pin.

Interrupt cycle register

INTR output Description

CT3 CT2 CT1 CT0

0

*

*

1

0 0 OFF Interrupt halt

0

*

0 1 ON Fixing the INTR pin at low level

0

*

1 0 0.977ms Cycle: 0.977ms (1/1024Hz) Duty 50% *

2

0

*

1 1 0.5s Cycle: 0.5s (1/2Hz) *

3

1 0 0 0 1s Every second *

4

1 0 0 1 10s

Every 10 seconds *

4

(For display of second digits: 00, 10, 20, 30, 40 and 50)

1 0 1 0 1 minute Every minute (00 second) *

4

1 0 1 1 10 minutes

Every 10 minutes (00 second) *

4

(For display of minute digits: 00, 10, 20, 30, 40 and 50)

1 1 0 0 1 hour Every hour (00 minute and 00 second) *

4

1 1 0 1 1 day Every day (00 hour, 00 minute and 00 second a.m.) *

4

1 1 1 0 1 week

Every week *

4

(0 week, 0 hour, 00 minute and 00 second a.m.)

1 1 1 1 1 month

Every month *

4

(1 day, 0 hour, 00 minute and 00 second a.m.)

*

1) The symbol “*” in the above table indicates 0 or 1.

0.977ms

Interrupt

(Second count-up)

Interrupt

(Second count-up)

Setting CTFG bit to 0

CTFG

INTR

CTFG

INTR

0.5s

0.488ms

CTFG

INTR

*

2)

*

3)

*

4)

RS5C316A/B

11

2.2 Control Register 2 (at Fh)

D3 D2 D1 D0

12/24

NOP BANK TEST

12/24 NOP BANK TEST

(For write operation)

(For read operation)

Bit for Testing

*

1

TEST

Description

0
1

Testing mode
Ordinary operation mode

BANK

Description

0
1

Clock/calendar counter
Alarm register

Bank Selection Bit

*

2

The NOP bit can be set to 0 for ordinary operation having no use for
anything.

12/24

Description

0
1

12-hour time display system (separate for mornings and afternoons)
24-hour time display system

12/24-hour Time Display System Selection Bit

*

3

*

1) (TEST) Set the TEST bit to 1 in ordinary operation. TEST bit is set automatically to 1 when the CE pin is “L”.

*

2) (BANK) There is no need to designate BANK bit for Interrupt cycle register and Control register 1/2.

*

3) (12/24) The 12/24 bit specifies time digit display in BCD code.

Either the 12-hour or 24-hour time display system should be selected before time setting.

24-hour time display system 12-hour time display system 24-hour time display system 12-hour time display system

00 12 (AM12) 12 32 (PM12)
01 01 (AM 1) 13 21 (PM 1)
02 02 (AM 2) 14 22 (PM 2)
03 03 (AM 3) 15 23 (PM 3)
04 04 (AM 4) 16 24 (PM 4)
05 05 (AM 5) 17 25 (PM 5)
06 06 (AM 6) 18 26 (PM 6)
07 07 (AM 7) 19 27 (PM 7)
08 08 (AM 8) 20 28 (PM 8)
09 09 (AM 9) 21 29 (PM 9)
10 10 (AM10) 22 30 (PM10)
11 11 (AM11) 23 31 (PM11)

RS5C316A/B

12

Day-of-the-week 12-hour system 12-hour system

Setting alarm time

Sun. Mon. Tue. Wed. Thu. Fri. Sat. 10- 1- 10- 1- 10- 1- 10- 1­AW0 AW1 AW2 AW3 AW4 AW5 AW6 hour hour min min hour hour min min

AM 00:00 every day 1 1 1 1 1 1 1 1 2 0 0 0 0 0 0

AM 01:30 every day 1 1 1 1 1 1 1 0 1 3 0 0 1 3 0

AM 11: 59 every day 1 1 1 1 1 1 1 1 1 5 9 1 1 5 9
PM 00:00

0 1 1 1 1 1 0 3 2 0 0 1 2 0 0

on Monday through Friday

PM 01:30 on Sunday 1 0 0 0 0 0 0 2 1 3 0 1 3 3 0
PM 11:59 on Monday,

0 1 0 1 0 1 0 3 1 5 9 2 3 5 9

Wednesday, and Friday

2.3 Interrupt cycle Register (at 7h)

D3 D2 D1 D0

AW3 AW2 AW1 AW0

(For read/write) day-of-the-week 1 (at0h)
ALC AW6 AW5 AW4 (For read/write) day-of-the-week 2 (at1h)
AM8 AM4 AM2 AM1 (For read/write) 1-minute time digit (at2h)

*

AM40 AM20 AM10 (For read/write) 10-minute time digit (at3h)

AH8 AH4 AH2 AH1

(For read/write) 1-hour time digit (at 4h)
ALE

*

AP/A, AH

20

AH10

(For read/write) 10-hour time digit (at5h)

2.4 Alarm registers for day-of-the-week, 1-minute, 10-minute, 1-hour, 10-hour (BANK1, at 0h-5h)

*

1) The “*” mark in the above table indicates data which are set to 0 for read cycle and not set for write cycle.

*

2) 10-hour time digit indicates AP/A and AH20 with 12-hour and 24-hour time system respectively.

*

3) Make sure set an actual time-data to the alarm registers when the alarm function is activated as any imaginary alarm-data will never be match with
the actual time.

*

4) The INTR pin can output matched alarm interruption when the ALC bit is set 0 and halt output when the ALC bit is set to 1.

*

5) The alarm function is disabled when the ALE bit is set 0 and is enables when the ALE bit is set 1.

*

6) Examples of setting alarm time

*

7) Hour digits show “12” and “32” when the time is AM 00:00 and PM 00:00 respectively in the 12-hour system.

*

8) No alarm interruption is output when all the bit from AW0 through AW6 is set to 0.

*

9) Each of the AW0 through AW6 corresponds to the day-of-the-week counter such as (W4, W2, W1)=(0, 0, 0) through (1, 1, 0). Designation of day-of­the-week and AW

0 through AW6 in the above table is one example.

*

1) (CT3 to CT0)
The CT

3 to CT0 bits are used to select the interrupt cycle and output mode at the INTR pin. There are two interrupt modes selectable: the pulse

mode (when the CT

3 bit is set to 0) and the level mode (when the CT3 bit is set to 1). The interrupt cycle and output mode at the INTR pin are shown

in detail in the section on the CTFG bit in “2.1 Control Register 1 (at Eh)”.

D3 D2 D1 D0

CT3 CT2 CT1 CT0 (For write operation)

3

CT

CT2 CT1 CT0

(For read operation)

Bits for selecting the interrupt cycle and output mode at the INTR pin

1

*

RS5C316A/B

13

D3 D2 D1 D0

*

W4 W2 W1

(For read/write) Day-of-the-week counter

*

1) The “*” mark indicates data which are set to 0 for read cycle and not set for write cycle.

*

2) Day-of-the-week digits are incremented by 1 when carried to 1-day digits.

*

3) Day-of-the-week digits display (incremented in septimal notation):
(W

4, W2, W1)=(000) → (001) → ····· → (110) → (000)

The relation between days of the week and day-of-the-week digits is user changeable (e.g. Sunday=000).

*

4) The (W4, W2, W1) should not be set to (111).

3.2 Day-of-the-week counter (BANK 0, at 6h)

D3 D2 D1 D0

S8 S4 S2 S1 (For read/write) 1-second time digit (at 0h)

*

S40 S20 S10 (For read/write) 10-second time digit (at1h)

M8 M4 M2 M1

(For read/write) 1-minute time digit (at2h)

*

M40 M20 M10

(For read/write) 10-minute time digit (at3h)

H8 H4 H2 H1 (For read/write) 1-hour time digit (at4h)

* *

P/A or H20 H10 (For read/write) 10-hour time digit (at5h)

3. Counters

3.1 Clock counter (BANK 0, at 0h-5h)

*

1) The “*” mark indicates data which are set to 0 for read cycle and not set for write cycle.

*

2) Any carry to 1-second digits from the second counter is disabled when the WTEN bit (of the control register 1) is set to 0.

*

3) Time digit display (BCD code):
Second digits: Range from 00 to 59 and carried to minute digits when incremented from 59 to 00.
Minute digits : Range from 00 to 59 and carried to hour digits when incremented from 59 to 00.
Hour digits : Range as shown in the section on the 12/24 bit and carried to day and day-of-the-week digits when incremented from 11 p.m. to 12

a.m. or 23 to 00.

*

4) Any registered imaginary time should be replaced with actual time as carrying to such registered imaginary time digits from lower-order ones cause
the clock counter to malfunction.

RS5C316A/B

14

D3 D2 D1 D0
D8 D4 D2 D1 (For read/write) 1-day calendar digit (at8h)

* *

D20 D10 (For read/write) 10-day calendar digit (at 9h)

MO8 MO4 MO2 MO1 (For read/write) 1-month calendar digit (atAh)

* * *

MO10

(For read/write) 10-month calendar digit (atBh)

Y8 Y4 Y2 Y1 (For read/write) 1-year calendar digit (atCh)

Y

80 Y40 Y20 Y10 (For read/write) 10-year calendar digit (atDh)

3.3 Calendar counter (BANK 0, at 8h-Dh)

*

1) The “*” mark indicates data which are set to 0 for read cycle and not set for write cycle.

*

2) The automatic calendar function provides the following calendar digit displays in BCD code.
Day digits : Range from 1 to 31 (for January, March, May, July, August, October, and December).

Range from 1 to 30 (for April, June, September, and November).
Range from 1 to 29 (for February in leap years).
Range from 1 to 28 (for February in ordinary years).

Carried to month digits when cycled to 1.
Month digits: Range from 1 to 12 and carried to year digits when cycled to 1.
Year digits : Range from 00 to 99 and counted as 00, 04, 08, ..., 92, and 96 in leap years.

*

3) Any registered imaginary time should be replaced with actual time as carrying to such registered imaginary time digits from lower-order ones cause
the clock counter to malfunction.

RS5C316A/B

15

USAGES

1. Read Data (For the RS5C316A)

The real-time clock becomes accessible by switching the CE pin from the low level to high level to enable inter­facing with the CPU and then inputting setting data (control bits and address bits) to the SIO pin in synchronization
with shift clock pulses from the SCLK pin. The input data are registered in synchronization with the falling edge of
the SCLK. When the data is read, the read cycle shall be set by control bits then registered data can be read out
from SIO pin in synchronization with the rising edge of the SCLK.

• Control bits R/W: Establishes the read mode when set to 1, and the write mode when set to 0.

AD: Writes succeeding addressing bits (A3-A0) to the address register when set to 1 with the

DT bit set to 0 and performs no such write operation in any other case.

DT: Writes data bits to counter or register specified by the address register set just before

when set to 1 with the R/W and AD bits set equally to 0 and performs no such write oper­ation in any other case.

• Address bits A3-A0: Inputs the bits MSB to LSB in the address table describing the functions.

1.1 Read Cycle Flow

1. The CE pin is switched from “L” to “H”.

2. Four control bits (with the first bit ignored) and four read address bits are input from the SIO pin. At this time,

control bits R/W and AD are set equally to 1 while a control bit DT is set to 0. (see the SCLK 1A-8A)

3. The SIO pin enters the output mode at the rising edge of the shift clock pulse 2B from the SCLK pin while the

four read bits (MSB → LSB) at designated addresses are output at the rising edge of the shift clock pulse 5B.

(see the figure below)

4. Then, the SIO pin returns to the input mode at the rising edge of the shift clock pulse 1C. Afterwards control bits

and address bits are input at the shift clock pulses 1C in the same manner as at the shift clock pulse 1A.

5. At the end of read cycle, the CE pin is switched from “H” to “L” (after

tCEH from the falling edge of the eighth

shift clock pulse from the SCLK pin). Following on read cycle, write operation can be performed by setting con-

trol bits in the write mode at the shift clock pulse 1C and later with the CE pin held at “H”.

1A 2A 3A 4A 5A 6A 7A 8A 1B 2B 3B 4B 5B 6B 7B 8B 1C 2C 3C

R/W

AD DT A3 A2 A1 A0

– – – D3 D2 D1 D0

R/W

AD

* *

CE

SCLK

Input to
SIO pin

Output
from SIO
pin

Writing to shift
register

Writing to address
register

Setting of
control bits

Control bits

(Hiz) (Hiz)

(Hiz)

Read data

Setting of SIO
pin in output
mode

Shifting data Setting of SIO

pin in input
mode

(Internal processing)

Address bits

*

) In the above figure, the “*” mark indicates arbitrary data; the “–” mark indicates unknown data.

The “ ” mark indicates data which are available when the SIO pin is held at “H”, “L”, or Hiz level.
The diagonally shaded area of the CE and the SCLK pins indicate “H” or “L”.

RS5C316A/B

16

2. Write Data (For the RS5C316A)

Writing data to the real-time clock requires inputting setting data (control bits, address bits and data bits) to the

SIO pin and then establishing the write mode by using a control bit R/W in the same manner as in read operation.

• Data bits D3-D0: Inputs the data bits MSB to LSB in the addressing table describing the functions.

2.1 Write Cycle Flow

1. The CE pin is switched from “L” to “H”.

2. Four control bits (with the first bit ignored) and four write address bits are input from the SIO pin. At this time,
control bits R/W and DT are set equally to 0 while a control bit AD is set to 1. (see the SCLK 1A-8A)

3. Four control bits and four bits of data to be written are input in the descending order of their significance.
At this time, control bits R/W and AD are set equally to 0 while a control bit DT is set to 1. (see the clock 1B-8B)

4. When write cycle is continued, control bits and address bits are input at the shift clock pulse 1C and later in the
same manner as at the shift clock pulse 1A.

5. At the end of write operation, control bits R/W, AD, and DT are set equally to 0 (at the falling edge of shift clock
pulse 5A and later from the SCLK pin) or the CE pin is switched from “H” to “L” (after

tCEH from the falling edge

of the eighth shift clock pulse from the SCLK pin). Following on write cycle, read operation can be performed by
setting control bits in the read mode at the shift clock pulse 1C and later with the CE pin held at “H”.

1A 2A 3A 4A 5A 6A 7A 8A 1B 2B 3B 4B 5B 6B 7B 8B 1C 2C 3C

R/W

AD DT A3 A2 A1 A0

R/W AD DT D3 D2 D1 D0

R/W

AD

* * *

*

CE

(Internal processing)

SCLK

Input to
SIO pin

Output
from
SIO pin

Writing to shift
register

Writing to address
register

Setting of
control bits

End of write
operation

Setting of
control bits

Control bits Address bits

Control bits Data bits

(Hiz) (Hiz)

*

) In the above figure, the “*” mark indicates arbitrary data; and the diagonally shaded area of CE and SCLK indicates “H” or “L”.

*

) Control bits and address bits are described in the previous section on read cycle.

RS5C316A/B

17

3. Read Data (For the RS5C316B)

The real-time clock becomes accessible by switching the CE pin from the low level to high level to enable inter­facing with the CPU and then inputting setting data (control bits and address bits) to the SIO pin in synchronization
with shift clock pulses from the SCLK pin. The input data are registered in synchronization with the rising edge of
the SCLK. When the data is read, the read cycle shall be set by control bits then registered data can be read out
from SIO pin in synchronization with the falling edge of the SCLK.

• Control bits R/W: Establishes the read mode when set to 1, and the write mode when set to 0.

AD: Writes succeeding addressing bits (A3-A0) to the address register when set to 1 with the

DT bit set to 0 and performs no such write operation in any other case.

DT: Writes data bits to counter or register specified by the address register set just before

when set to 1 with the R/W and AD bits set equally to 0 and performs no such write oper­ation in any other case.

• Address bits A3-A0: Inputs the bits MSB to LSB in the address table describing the functions.

3.1 Read Cycle Flow

1. The CE pin is switched from “L” to “H”.

2. Four control bits (with the first bit ignored) and four read address bits are input from the SIO pin. At this time,

control bits R/W and AD are set equally to 1 while a control bit DT is set to 0. (see the SCLK 1A-8A)

3. The SIO pin enters the output mode at the falling edge of the shift clock pulse 2B from the SCLK pin while the

four read bits (MSB → LSB) at designated addresses are output at the falling edge of the shift clock pulse 5B.

(see the figure below)

4. Then, the SIO pin returns to the input mode at the falling edge of the shift clock pulse 1C. Afterwards control

bits and address bits are input at the shift clock pulses 1C in the same manner as at the shift clock pulse 1A.

5. At the end of read cycle, the CE pin is switched from “H” to “L” (after

tCEH from the rising edge of the eighth

shift clock pulse from the SCLK pin). Following on read cycle, write operation can be performed by setting con-

trol bits in the write mode at the shift clock pulse 1C and later with the CE pin held at “H”.

1A 2A 3A 4A 5A 6A 7A 8A 1B 2B 3B 4B 5B 6B 7B 8B 1C 2C 3C

R/W

AD DT A3 A2 A1 A0

– – – D3 D2 D1 D0

R/W

AD

*

*

CE

SCLK

Input to
SIO pin

Output
from SIO
pin

Writing to shift
register

Writing to address
register

Setting of
control bits

Control bits Address bits

(Hiz) (Hiz)

(Hiz)

Read data

(Internal processing)

Shifting data Setting of SIO

pin in input
mode

Setting of SIO
pin in output
mode

*

) In the above figure, the “*” mark indicates arbitrary data; the “–” mark indicates unknown data.

The “ ” mark indicates data which are available when the SIO pin is held at “H”, “L”, or Hiz level.
The diagonally shaded area of the CE and the SCLK pins indicate “H” or “L”.

RS5C316A/B

18

4. Write Data (For the RS5C316B)

Writing data to the real-time clock requires inputting setting data (control bits, address bits and data bits) to the

SIO pin and then establishing the write mode by using a control bit R/W in the same manner as in read operation.

• Data bits D3-D0: Inputs the data bits MSB to LSB in the addressing table describing the functions

4.1 Write Cycle Flow

1. The CE pin is switched from “L” to “H”.

2. Four control bits (with the first bit ignored) and four write address bits are input from the SIO pin. At this time,
control bits R/W and DT are set equally to 0 while a control bit AD is set to 1. (see the SCLK 1A-8A)

3. Four control bits and four bits of data to be written are input in the descending order of their significance.
At this time, control bits R/W and AD are set equally to 0 while a control bit DT is set to 1. (see the SCLK 1B-8B)

4. When write cycle is continued, control bits and address bits are input at the shift clock pulse 1C and later in the
same manner as at the shift clock pulse 1A.

5. At the end of write operation, control bits R/W, AD, and DT are set equally to 0 (at the rising edge of shift clock
pulse 5A and later from the SCLK pin) or the CE pin is switched from “H” to “L” (after t

CEH from the rising edge

of the eighth shift clock pulse from the SCLK pin). Following on write cycle, read operation can be performed by
setting control bits in the read mode at the shift clock pulse 1C and later with the CE pin held at “H”.

R/W

AD DT A3 A2 A1 A0

R/W AD DT D3 D2 D1 D0

R/W

AD

* * *

*

CE

(Internal process)

SCLK

Input to
SIO pin

Output
from SIO
pin

Writing to shift
register

Writing to address
register

Setting of
control bits

End of write
operation

Setting of
control bits

Control bits Address bits

Control bits Data bits

(Hiz) (Hiz)

1A 2A 3A 4A 5A 6A 7A 8A 1B 2B 3B 4B 5B 6B 7B 8B 1C 2C 3C

*

) In the above figure, the “*” mark indicates arbitrary data; and the diagonally shaded area of CE and SCLK indicates “H” or “L”.

*

) Control bits and address bits are described in the previous section on read cycle.

RS5C316A/B

19

5. CE Pin

1) Switching the CE pin to the high level enables the SCLK/SCLK and SIO pins, allowing data to be serially read
from and written to the SIO pin in synchronization with shift clock pulses input from the SCLK/SCLK pin.

2) Switching the CE pin to the low level or opening disables the SCLK/SCLK and SIO pins, causing high imped­ance and resetting the internal interfacing circuits such as the shift register. While data of the address register
and bank bit which have been written just before should be preserved.

3) The CE pin should be held at the low level or open state when no access is made to the RS5C316.
The CE pin incorporates a pull-down resistor.

4) During system power-down (being back-up battery powered), the low-level input of the CE pin should be brought
as close as possible to the VSS level to minimize the loss of charge in the battery.

5) Holding the CE pin at the high level for more than 2.5 seconds mainly forces 1Hz interrupt pulses to be output
from the INTR pin for oscillation frequency measurement. When the CE pin is held at the high level for less
than 1.5 seconds, no pulse is output.

6) The CE pin should be held at the low level in order to enable oscillator halt sensing. Holding the CE pin at the
high level, therefore, disables oscillator halt sensing, retaining the value of the XSTP (oscillator halt sensing) bit
which exists immediately before the CE pin is switched to the high level.

*

) RS5C316A: SCLK

RS5C316B: SCLK

Considerations

When the power turns on from 0V, the CE pin should be set low or open once.

SCLK/SCLK

*

SIO

CE

Shift clock pulses

Address Data
Write Data

Read Data

Read control bit
Control bit

RS5C316A/B

20

1) When applying an external input of clock pulses (32.768kHz) to the OSCIN pin:

DC coupling ............Prohibited due to mismatching input levels.

AC coupling.............Permissible except that unpredictable results may occur in oscillator halt sensing due

to possible sensing errors caused by noises, etc.

2) Avoid using the oscillator output of the RS5C316 (from the OSCOUT pin) to drive any other IC for the pur­pose of ensuring stable oscillation.

1) Mount the crystal oscillators and C

G in the closest possible position to the IC.

2) Avoid laying any signal or power line close to the oscillation circuit (particularly in the area marked with
“← A →” in the above figure).

3) Apply the highest possible insulation resistance between the OSCIN or OSCOUT pin and the PCB.

4) Avoid using any long parallel line to wire the OSCIN or OSCOUT pin.

5) Take extreme care not to cause condensation, which leads to various problems such as oscillation halt.

6. Configuration of Oscillating Circuit

RF

RD

CD

OSCIN

OSCOUT

32kHz

VDD

VDD

CG

VSS

A

Typical external device:

X'tal : 32.768kHz

(R

1=30kΩ TYP.)

(C

L=6pF to 8pF)

C

G=8pF to 20pF

Typical values of internal devices

R

F=15MΩ (TYP.)

R

D=60kΩ (TYP.)

C

D=10pF (TYP.)

Considerations in Mounting Components Surrounding Oscillating Circuit

Other Relevant Considerations

*

) The oscillation circuit is driven at a constant voltage of about 1.5V relative to the Vss level.

Consequently, it generates a wave form having a peak-to-peak amplitude of about 1.5V on the positive side of the Vss level.

RS5C316A/B

21

Considerations in Use of XSTP Bit

7. Oscillator Halt Sensing

Oscillation Halt can be sensed through monitoring the XSTP bit with preceding setting of the XSTP bit to 0 by
writing any data to the control register 1. Upon oscillator halt sensing, the XSTP bit is switched from 0 to 1. This
function can be applied to judge clock data validity.

*

1) While the CE pin is held at the low level, the XSTP bit is set to 1 upon power-on from 0V.
Note that any instantaneous power disconnection may cause operational failure. When the CE pin is held at the high level, oscillation halt is not
sensed and the value of the XSTP bit when the CE pin is held at the low level is retained.

*

2) Once oscillation halt has been sensed, the XSTP bit is held at 1 even if oscillation is restarted.

Ensure error-free oscillation halt sensing by preventing the following:

1) Instantaneous disconnection of VDD

2) Condensation on the crystal oscillator

3) Generation of noise on the PCB in the crystal oscillator

4) Application of voltage exceeding prescribed maximum ratings to the individual pins of the IC

Power-on from 0V

*

1

XSTP

Oscillation haltWriting of data to

control register 1

(in the presence of oscillation)

Oscillation restart

*

2

RS5C316A/B

22

8. Typical Power Supply Circuit

1) Connect the capacitance of the oscillation circuit to the Vss pin.

2) Mount the high-and low-frequency by-pass capacitors in paral­lel and very close to the RS5C316.

3) Connect the pull-up resistor of the INTR pin to two different
positions depending on whether the resistor is in use during
battery back-up.

• When not in use during battery back-up

...........Position A in the left figure

• When in use during battery back-up

...........Position B in the left figure

4) Timing of power-on, power-off and CE pin refer to following figure.

5) When a diode are in use in place of the components surround­ed by dotted lines, note that applying voltage to any input pins
should be less than the rating of V

DD +0.3V by using of schot-

tky diode.

OSCIN

OSCOUT

VDD

RS5C316

VSS

B

A

System

supply

voltage

INTR

C

0V

VDD

CE

D

0.2V

DD

MIN. 0µs MIN. 0µs MIN. 0µs

C, D, E: Minimum operating voltage for CPU

0.2V

DD 0.2VDD

Battery voltage

System supply voltage

E

9. Oscillation Frequency Adjustment

9.1 Oscillation Frequency Measurement

1) Switch the CE pin to the high level and use a frequen­cy counter to measure a 1Hz interrupt pulse output
from the INTR pin about 2.5 seconds later.

2) Ensure that the frequency counter has more than six
digits (on the order of 1 ppm).

3) Place the C

G between the OSCIN pin and the VSS lev-

el and pull up the INTR pin output to the VDD.

INTR

OSCOUT

OSCIN

VDD

CE

VSS

32kHz

+5V or +3V

Frequency

counter

C

G

RS5C316A/B

23

Any rise or fall in ambient temperature from its reference value ranging from 20 to 25 degrees Celsius causes
a time delay for a 32kHz crystal oscillator. It is recommendable, therefore, to set slightly high oscillation fre­quency at room temperature.

9.2 Oscillation Frequency Adjustment

After adjustment, oscillation frequency is subject to fluctuations of an ambient temperature and supply voltage. See
“12. Typical Characteristic Measurements”.

Select crystal oscillator

NO

OK

OK

NO

Fix CG

(For fixed capacitance) (For variable capacitance)

Change C

L

value of crystal

Optimize CG

END

END

Fix the capacitance of CG

Optimize central

variable capacitance value

Make fine frequency adjustment

with variable capacitance.

Change CL

value of crystal

*

1

*

3

*

3

*

2

*

1) To ensure that the crystal is matched to the IC, inquire its crystal supplier about its CL (load capacitance) and R1 (equivalent series resistance) values.
It is recommended that the crystal should have the C

L value range of 6 to 8pF and the typical R1 value of 30kΩ.

*

2) To allow for the possible effects of floating capacitance, select the optimum capacitance of the CG on the mounted PCB. The standard and recom­mendable capacitance values of the C

G range from 5 to 24pF and 8 to 20pF, respectively. When you need to change the frequency to get higher

accuracy, change the C

L value of the crystal.

*

3) Collate the central variable capacitance value of the CG with its oscillation frequency by adjusting the angle of rotation of the variable capacitance of
the C

G in such a manner that the actual variable capacitance value is slightly smaller than the central variable capacitance value. (It is recommended

that the central variable capacitance value should be slightly less than one half of the actual variable capacitance value because the smaller is vari­able capacitance, the greater are fluctuations in oscillation frequency.) In the case of an excessive deviation of the oscillation frequency from its
required value, change the C

L value of the crystal.

Note

RS5C316A/B

24

10. Interrupt Operation

Two interrupt operations are available:

1) Alarm interrupt...........When a registered time for alarm (such as day-of-the-week, hour or minute) coincide with

calendar counter (such as day-of-the-week, hour or minute) interrupt to the CPU are
requested with INTR pin being “L” (ON).

2) Periodic interrupt ......The INTR pin comes to a “L” (ON) state every registered period outputting interrupt

request.

Function diagram of alarm and periodic interrupts are shown as follows:

10.1 Alarm Interrupt

For setting an alarm time, designated time such as day-of the week, hour or minute should be set to the alarm
registers being ALE bit to 0. After that set the ALE bit to 1, from this moment onward when such registered alarm
time coincide with the value of calendar counter the INTR comes down to “L” (ON). The INTR output can be con­trolled by operating to the ALE and ALFG bits.

*

1) Setting the ALC into 1 halt output of the alarm interrupt from INTR pin.

*

2) Both of alarm and periodic interrupt can operate regardless of the state of CE pin, “H” or “L”.

*

1) The “*” mark indicates the time when the registered alarm day-of-the-week and time coincide with calendar counter.

*

2) Above figure describes in case of no periodic interruption.

*

3) ALFG indicates a reverse state of INTR output.

ALC

INTR

Alarm interrupt

Periodic interrupt

Alarm-calendar

coincident period

(1 min.)

*

*

*

*

INTR

INTR

ALE←1

ALE←1 ALFG←0

ALE←0 ALE←0ALE←1

MAX.61.1µs

RS5C316A/B

25

Interrupt cycle register

INTR output Description

CT3 CT2 CT1 CT0

0

*

*

1

0 0 OFF Interrupt halt

0

*

0 1 ON Fixing the INTR pin to the low level

0

*

1 0 0.977ms Cycle: 0.977ms (1/1024Hz) Duty 50%

0

*

1 1 0.5s Cycle: 0.5s (1/2Hz)

1 0 0 0 1s Every second

1 0 0 1 10s

Every 10 seconds
(For display of second digits: 00, 10, 20, 30, 40 and 50)

1 0 1 0 1 minute Every minute (00 second)

1 0 1 1 10 minutes

Every 10 minutes

(For display of minute digits: 00, 10, 20, 30, 40 and 50)
1 1 0 0 1 hour Every hour (00 minute and 00 second)
1 1 0 1 1 day Every day (0 hour, 00 minute and 00 second a.m.)
1 1 1 0 1 week Every week (0 week, 0 hour, 00 minute and 00 second a.m.)
1 1 1 1 1 month Every month (1st day, 0 hour, 00 minute and 00 second a.m.)

10.2 Periodic (Clock) Interrupt

The INTR pin output, the interrupt cycle register, and the CTFG bit can be used to interrupt the CPU in a certain
cycle. The interrupt cycle register can be used to select either one of two interrupt output modes: the pulse mode
(when the CT

3 bit is set to 0) and the level mode (when the CT3 bit is set to 1).

10.2-1 Interrupt Cycle Selection

10.2-2 Pulse mode Interrupt

When the CT3 bit is set to 0 and provides four interrupt cycles, off, on, 1024Hz, and 2Hz can be selected. The
CTFG bit cannot be set because it is used for output monitoring.

10.2-3 Level mode Interrupt

When the CT3 bit is set to 1, clock-interlocked cycles in increments of one second to one month can be selected.
The CTFG bit can be written; writing 1 to the CTFG bit switches the INTR pin to the low level while writing 0 to the
CTFG bit turns off the INTR pin.

*

1) The “*” mark indicates 0 or 1.

T1

0.488ms

CTFG

INTR

Interrupt

(Second count-up)

Interrupt

(Second count-up)

Writing 0 to CTFG bit

CTFG

INTR

1024Hz : T1= 0.977ms
2Hz : T1= 500ms

RS5C316A/B

26

11. Typical Application

*

1) Connect the capacitance of the oscillation circuit to the VSS pin.

*

2) Mount the high-and low-frequency by-pass capacitors in parallel and very close to the RS5C316.

*

3) Connect the pull-up resistor of the INTR pin to two different positions depending on whether the resistor is in use during battery back-up:

(I) When not in use during battery back-up.............Position A in the above figure

(II) When in use during battery back-up...................Position B in the above figure

*

4) When using a “D” circuit in place of “C”, note that forward voltage of diode should be minimized to eliminate applying excess voltage to input pins.
(Take the utmost care on system powering-ON and-OFF).

VCC

VSS

OSCIN

OSCOUT

VDD

VSS

INTR

CE

SCLK/SCLK

SIO

CPU RS5C316A/B

System power

supply

B A

System power supply

VDD

D

C

or

System

power

supply

RS5C316A/B

27

12. Typical Characteristic Measurements

12.3 Operational Current vs. SCLK/SCLK Frequency

12.1 Standby Current vs. C

G 12.2 Standby Current vs. VDD

12.4 Standby Current vs. Temperature

Standby Current IDD (µA)

Topt = 25°C

C

G (pF)

0

0.0

1.0

2.0

10 155 20 25 30

VDD = 5V

VDD = 3V

CG = 10pF

Standby Current IDD (µA)

Topt = 25°C

V

DD (V)

0

0.0

1.0

2.0

2 4 6

VDD = 3V

VDD = 5V

Operational Current IOPR (mA)

Topt = 25°C

SCLK/SCLK Frequency (MHz)

0.01

0.001

0.01

0.1

1

0.1 1 10

Standby Current IDD (µA)

CG = 10pF

Temperature Topt (°C)

–60 –40 –20

0.0

1.0

2.0

0 20 40 60 80 100

VDD = 6V

VDD = 3V

CG=10pF
X'tal : R

1=30kΩ

Topt=25˚C
Input Pin : VDD or VSS
Output Pin : Open

OSCIN

OSCOUT

INTR

VSS

VDD

A

CG

X'tal

V

DD

Frequency counter

RS5C316A/B

28

12.7 Oscillation Frequency Deviation
vs. Temperature (f0: Topt=25°C reference)

12.5 Oscillation Frequency Deviation vs. C

G

(f0: CG=10pF reference)

12.6 Oscillation Frequency Deviation vs. V

DD

(f0: VDD=4V reference)

12.8 Oscillation Start Time vs. V

DD

Oscillation Frequency Deviation

∆f/f0 (ppm)

VDD = 3V, Topt = 25°C

C

G (pF)

0

–40

–20

0

20

40

60

80

10 155 20 25 30

Oscillation Frequency Deviation

∆f/f0 (ppm)

CG = 10pF, Topt = 25°C

V

DD (V)

0

–4

–3

–2

–1

0

1

2 31 4 5 6

Oscillation Frequency Deviation

∆f/f0 (ppm)

VDD = 3V, CG = 10pF

Temperature Topt (°C)

–40

–80

–70

–60

–50

–40

–30

–20

–10

0

10

0 20–20 40 60 10080

CG = 20pF

CG = 10pF

Oscillation Start Time (s)

Topt = 25°C

V

DD (V)

0

0.0

0.5

1.0

2 31 4 5 6

12.9 VDS vs. IDS for Nch Open Drain Output

VDD = 3V

VDD = 5V

Nch Open Drain Output

I

DS (mA)

Topt = 25°C

V

DS (V)

0.0

0

10

20

30

40

50

1.0 1.50.5 2.0

RS5C316A/B

29

Ensure stable oscillation by preventing the following:

1) Condensation on the crystal oscillator

2) Instantaneous disconnection of power

3) Generation of clock noises, etc, in the crystal
oscillator

4) Charge of voltage exceeding prescribed maxi­mum ratings to the individual pins of the IC

13. Typical Software-based Operations

13.1 Initialization upon Power-on

13.2 Write Operation to Clock and Calendar Counters

Start

XSTP=0?

BSY=0?

Interrupt cycle register←0h

Control register 2←3h

(BANK←1)

10-hour alarm register←0h

(ALE←0)

Control register 1←3h

Control register 2←1h, 9h
Set clock and calendar
counters and interrupt cycles.

Wait or

other

operations.

Power-on

YES

NO

YES

NO

*

1

*

2

*

3

*

4

*

6

*

5

BSY=0?

Write to clock and
calendar

counters.

CE=L

Wait or

other

operations.

CE=L

Control register 1←0h

CE=H

YES

NO

*

1

*

2

*

3

*

4

*

1) Switch the CE pin to the low level immediately after power-on.

*

2) When not making oscillation halt sensing (data validity), the XSTP bit
need not be checked.

*

3) Turn off the INTR pin, whose output is uncertain at power-on.

*

4) Set the ADJ bit to 1. When writing control register 1, if the oscillator has
operated, the XSTP bit is changed from 1 to 0.

*

5) It takes about 0.1 to 2 seconds to be set the BSY bit to 0 from oscillation
starting upon power-on from 0V. Provide an exit from an oscillation start
loop to prepare for oscillation failure.

*

6) Set the XSTP bit to 0 by writing data to the control register 1, and set to
the control register 2,
0h for the 12-hour time display system.
4h for the 24-hour time display system.

*

1) After switching the CE pin to the high level, hold it at the high level until
any subsequent operation requires switching it to the low level. (Note
that switching the CE pin to the low level sets the WTEN bit to 1.)

*

2) WTEN bit is set to 0.

*

3) The BSY bit is held at 1 for a maximum duration of 122.1µs.

*

4) Switch the CE pin to the low level to set the WTEN bit to 1. During write
operation to the clock and calendar counters, one 1-second digit carry
causes a 1-second increment while two 1-second digit carries also cause
only a 1-seconds increment, which, in turn, causes a time delay.

When Using the XSTP Bit

RS5C316A/B

30

Note

13.3 Read Operation from Clock and Calendar Counters

13.3-1

13.3-3

13.3-2

CTFG=1?

Read from clock and

calendar

counters.

Interrupt

operation

from any

other IC

Interrupt to CPU

Control register 1←2h

YES

NO

*

6

*

7

*

8

BSY=0?

Read from clock and

calendar

counters.

CE=L

Wait or

other

operations.

CE=L

Control register 1←0h

CE=H

YES

NO

*

1

*

2

*

3

*

4

Read from clock and

calendar

counters.

Again read 1-second
digit of clock

counter.

Two 1-second

digit

readings

match?

Read 1-second

digit of clock

counter.

NO

YES

*

5

*

5

*

5

Read data as described in 13.3-2 or 13.3-3 when it takes (1/1024) sec or more to set the WTEN bit from 0 to 1
(CE=L), the read operation described in 13.3-1 is prohibited as such a case.

*

1) to *4) These notes are the same as 13.2 notes *1) to *4).

*

5) When needing any higher-order digits than the minute digits, replace
second digits with minute digits. (Reading LSD one of the required digits
twice.)

*

6) Select the level mode as an interrupt mode by setting the CT3 bit to 1.

*

7) Write 0 to CTFG bit for turning off INTR pin.

*

8) Complete read operation within an interrupt cycle after interrupt genera­tion. (e.g. within 1 second)

RS5C316A/B

31

Control register 1←3h

*

1

XSTP=0?

Oscillation start

Wait or

other

operations.

Power-on

Control register 1←2h

YES

NO

*

1

*

2

CE←“L”

ALE←1

BANK←1

Set alarm (hour or minute,

day-of the week)

*

1

13.4 Write Operation to Alarm time

*

1) Non-existent alarm time can set in the alarm registers, but when it sets,
an alarm interrupt is disabled. To enable an alarm interrupt, existent
alarm time must be set in the alarm registers.

13.5 Second-digit Adjustment by ±30 seconds

*

1) Set the ADJ bit to 1.
(The BSY bit is held at 1 for a maximum duration of 122.1µs after the
ADJ bit is set to 1.)

13.6 Oscillation Start Judgment

*

1) The XSTP bit is set to 1 upon power-on from 0V.

*

2) It takes approximately 0.1 to 2 seconds to start oscillation. Provide an
exit from an oscillation start loop to prepare for oscillation failure.

Ensure stable oscillation by preventing the following:

1) Condensation on the crystal oscillator

2) Instantaneous disconnection of power

3) Generation of clock noises, etc, in the crystal
oscillator

4) Charge of voltage exceeding prescribed maxi­mum ratings to the individual pins of the IC

When Using the XSTP Bit

RS5C316A/B

32

CTFG=1?

Cyclic interrupt operation

Interrupt

operation

from any

other IC

Interrupt to CPU

Control register 1←2h

Set interrupt cycle register

YES

NO

*

1

*

2

ALFG=1?

Alarm interrupt operation

Interrupt

operation

from any

other IC

Interrupt to CPU

ALFG←0

Set alarm (hour or minute,

day-of the week)

YES

NO

*

1

ALE←1

13.7 Interrupt Operation

13.7-1 Cyclic Interrupt Operation

13.7-2 Alarm Interrupt Operation

*

1) Set the interrupt cycle register to the level mode by setting the CT3 bit to 1.

*

2) Write 0 to CTFG bit for turning off INTR pin.

*

1) Write 0 to ALFG bit for turning off INTR pin.

RS5C316A/B

33

0.15

+0.1

-

0.05

0.5±0.3

0° to 10°

0.1±0.1

0.15

0.1

M

0.22±0.1

1.15±0.1

0.775TYP.

0.65

1

4

6.4±0.3

4.4±0.2

8

5

3.5±0.3

0.3

2.7 MAX.

4.0±0.1

2.0±0.05

8.0±0.1

1.75

±

0.1

5.5±0.05

3.9

6.7

12.0±0.3

User Direction of Feed.

ø1.5

+0.1
–0

PACKAGE DIMENSIONS(Unit: mm)

TAPING SPECIFICATION(Unit: mm)

• RS5C316A/B (8pin SSOP, 0.65mm pitch)

The RS5C316A/B have one designated taping direction. The product designations for the taping components are
“RS5C316A-E2” and “RS5C316B-E2”.

RICOH COMPANY, LTD.
ELECTRONIC DEVICES DIVISION

HEADQUARTERS

13-1, Himemuro-cho, Ikeda City, Osaka 563-8501, JAPAN
Phone [phone] Fax [phone]

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JAPAN
Phone [phone] Fax [phone] · 1695

http://www.ricoh.co.jp/LSI/english/

RICOH CORPORATION
ELECTRONIC DEVICES DIVISION

SAN JOSE OFFICE

1996 Lundy Avenue, San Jose, CA 95131, U.S.A.
Phone [phone] Fax [phone]

http://www.ricoh-usa.com/semicond.htm