SGS Thomson Microelectronics M41T80 Datasheet

SERIAL ACCESS RTC WITH ALARMS

FEATURES SUMMARY

■ 2.0 TO 5.5V CLOCK OPERATING VOLTA GE

■ COUNTERS FOR TENTHS/HUNDREDTHS

OF SECONDS, SECONDS, MINUTES,
HOURS, DAY, DATE, MONT H , YEAR , and
CENTURY

■ SERIAL INTERFAC E SU PPO R TS I

(400KHz)

■ PROGRAMMABLE ALARM and INTERRUP T

FUNCTI ON

■ LOW OPERATING CURRENT OF 200µA

■ OPERATING TEMPERATURE OF –40 TO

85°C

2

C BUS

M41T80

Figure 2. 8-pi n S OI C Package

8

1

SO8 (M)

Figure 1. Logic Diagram

V

CC

XI

XO

SCL

SDA

M41T80

V

SS

IRQ/OUT/SQW
F

32k

AI07005

Table 1. Signal Names

XI

XO

IRQ

/OUT/

SQW

SDA Serial Data Input/Output
SCL Serial Clock Input

F

32k

V

CC

V

SS

Oscillator Input

Oscillator Output

Interrupt / Output Driver / Square
Wave (Open Drain)

32kHz Square Wave Output (Open
drain)

Supply Voltage
Ground

1/20October 2002

M41T80

TABLE OF CONTENTS

SUMMARY DESCRIPTION. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

8-pin SOIC Connections (Figure 3.) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

Block Diagram (Fi g ure 4 .) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

MAXIMUM RATING. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4

Absolute Maximum Rati ng s (Table 2.) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4

DC AND AC PARAMETERS. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

Operating and AC Measurement Conditions (Table 3.) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

AC Measurement I/O Waveform (Figure 5.) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

Capacitance (Table 4.) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

DC Characteristi cs (Table 5.) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

Crystal Electrical Characteristics (Table 6.). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6

OPERATION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7

2-Wire Bus Characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7

Serial Bus Data Transfer Sequence (Figure 6.) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .8

Acknowledgement Sequ ence (Figure 7.) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8

Bus Timing Requirements Sequence (Figure 8.) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9

AC Characteristics (Table 7.) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9

READ Mode. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 0

Slave Address Location (Figure 9.). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10

READ Mode Sequence (Figure 10.) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10

Alternative READ Mode Sequence (Figure 11.) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .11

WRITE Mode. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11

WRITE Mode Sequence (Figure 12.) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11

CLOCK OPERATION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12

TIMEKEEPER® Registers. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12

TIMEKEEPER® Register Map (Table 8.) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13

Full-time 32kHz Square Wave Output . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .15

Century Bit. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16

Alarm Interrupt Reset Waveform (Figure 13.) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14

Alarm Repeat Modes (Table 9.) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14

Square Wave Output Frequency (Table 10.). . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15

Century Bit. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16

Output Driver Pin. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16

Preferred Power-on Def a ult. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16

Preferred Power-on Def a ult Values (Table 11.) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16

PART NUMBERING . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17

PACKAGE MECHANICAL INFORMATION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18

REVISION HISTORY. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19

2/20

M41T80

SUMMARY DESCRIPTION

The M41T80 Serial Access TIMEKEEPER
SRAM is a low power Serial RTC with a built-in

32.768 KHz oscillator (external crystal controlled).
Eight registers (see Table 8, page 13) are used for
the clock/calendar func tion and a re configured in
binary coded decimal (BCD) format. An additional
12 registers provide status/control of Alarm, 32kHz
output, and Square Wave functions. Addresses
and data are transferred se rially via a t wo li ne, bi­directional I

2

C interface. The built-in address reg­ister is incremented automatically after each
WRITE or READ data byte.

Figure 3. 8-pin SOIC Connections

V

1

XI

2

XO

(1)

F

32k

V

SS

Note: 1. Open drain output.

M41T80

3
45

8

CC

7

IRQ/OUT/SQW

6

SCL
SDA

(1)

AI07006

®

Functions available to the user include a time-of­day clock/calendar, Alarm interrup ts, 32kHz out­put, and programmable Square Wave output. The
eight clock address locations contain the cent ury,
year, month, date, day, hour, minute, second and
tenths/hundredths of a second in 24 hour BCD for­mat. Corrections for 28, 29 (leap yea r - valid until
year 2100), 30 and 31 day months are made auto­matically.

The M41T80 is supplied in an 8-pin SOIC.

Figure 4. Block Diagram

CRYSTAL

SDA

SCL

Note: 1. Open Drain output

32KHz

OSCILLATOR

I2C

INTERFACE

REAL TIME CLOCK

CALENDAR

RTC W/ALARM

SQUARE WAVE

AF

IRQ/OUT/SQW

(1)

F

32k

AI07007

(1)

3/20

M41T80

MAXIMUM RATIN G

Stressing the device above the rating l isted in the
“Absolute Maximum Ratings” table may cause
permanent damage to the device. These are
stress ratings only and operation of the dev ice at
these or any other conditions above those indicat­ed in the Operating sections of this specification is

Table 2. Absolute Maximum Ratings

Sym Parameter Value Unit

T

STG

V

CC

T

SLD

V

IO

I

O

P

Note: 1. Reflow at peak temperature of 215°C to 225°C for < 60 sec onds (total thermal budg et not to exce ed 180°C for bet ween 90 to 12 0

Storage Temperature (VCC Off, Oscillator Off)

Supply Voltage –0.3 to 7 V

(1)

Lead Solder Temperature for 10 Seconds 260 °C

Input or Output Voltages –0.3 to Vcc+0.3 V

Output Current 20 mA

Power Dissipation 1 W

D

secon ds).

not implied. Exposure to Absol ute Maxim um Rat­ing conditions for extended periods may affect de­vice reliability. Refer also to the
STMicroelectronics SURE Program and oth er rel­evant quality documents.

–55 to 125

°C

4/20

DC AND AC PARAMETERS

This section summarizes the operat ing and mea­surement conditions, as well as the DC and AC
characteristics of the device. The parameters in
the following DC and AC Characteristic tables are
derived from tests performed under the M easure-

Table 3. Operating and AC Measurement Conditions

Parameter M41T80

M41T80

ment Conditions listed i n the relevant tables. De­signers should check that the operating conditions
in their projects match the measurement condi­tions when using the quoted parameters.

Supply Voltage (V
Ambient Operating Temperature (T
Load Capacitance (C

CC

)

)

A

)

L

2.0 to 5.5V

–40 to 85°C

100pF

Input Rise and Fall Times ≤ 50ns

0.2V

0.3V

to 0.8 V

CC

to 0.7 V

CC

Input Pulse Voltages
Input and Output Timing Ref. Voltages

Note: Output Hi -Z is define d as the point wh ere data is no longer driven.

Figure 5. AC Measurement I/O Waveform

0.8V

0.2V

CC

CC

0.7V

0.3V

AI02568

CC

CC

CC

CC

Table 4. Capacitance

Symbol

C

IN

(3)

C

OUT

t

LP

Note: 1. Effective capacitance measured with power suppl y at 5V; sampled only, not 100% tested.

2. At 25°C, f = 1MHz.

3. Outputs deselected .

Input Capacitance 7 pF
Output Capacitance 10 pF
Low-pass filter input time constant (SDA and SCL) 50 ns

Parameter

(1,2)

Min Max Unit

5/20

M41T80

Table 5. DC Characteristics

Symbol Parameter

Input Leakage

I

LI

Current
Output Leakage

I

LO

Current

I

CC2

I

Supply Current Switch Freq (SCL) = 400kHz

CC1

Supply Current

(2)

(standby)

V

Input Low Voltage –0.3

IL

V

Input High Voltage

IH

All Inputs = V

Switch Freq (SCL) = 0Hz

Output Low Voltage

V

OL

Output Low Voltage
(Open Drain)

Note: 1. Valid for Am bi ent Operat in g T em perature : TA = –40 to 85°C ; VCC = 2.0 to 5.5V (except where noted).

2. At 25°C.

3. For IRQ

/FT/OUT, RST, and 32kHz pins (Open Drain)

(3)

Test Condition

0V ≤ V

0V ≤ V

OUT

– 0.2V

CC

I

= 3.0mA 0.4

OL

IOL = 10mA

(1)

≤ V

IN

CC

≤ V

CC

32KE = 1

or SQWE = 1

32KE = 0

and SQWE = 0

Min Typ Max Unit

3.0V 30 µA

5.5V 200 µA

3.0V 1.8 3.0 µA

5.5V 35 µA

3.0V 1.5 2.4 µA

5.5V 31 µA

0.7V

CC

±1 µA

±1 µA

0.3V

CC

VCC + 0.3

0.4 V

V
V
V

Table 6. Crystal Electrical Characteristics

Sym

f

O

R

S

C

L

Note: 1. Externally s uppl ied i f us ing th e S O8 pa ckag e. STM icroe lec troni cs reco mm ends the K DS DT -38: 1TA/ 1TC 252E 127, Tun ing Fork

Type (thru-hole) or the DMX-26S: 1TJS125FH2A212, (SMD) quartz crystal for industrial temperature operations. KDS can be con­tacted at kouhou@kdsj .c o.jp or http ://www.kds j .c o.jp for further inform at i on on this crystal type.

2. Load capacitors are integrated within the M41T80. Circuit board layout considerations for the 32.768 kHz crystal of minimum trace
lengths an d i solation from RF generating signals should be taken into account.

Resonant Frequency 32.768 kHz
Series Resistance 60 kΩ
Load Capacitance 12.5 pF

Parameter

(1,2)

Min Typ Max Units

6/20