Rainbow Electronics DS1375 User Manual

General Description

The DS1375 digital real-time clock (RTC) is a low-power clock/calendar that does not require a crystal. The device operates from a digital clock input pin at one of four frequencies: 32.768kHz, 8.192kHz, 60Hz, or 50Hz. It maintains seconds, minutes, hours, day, date, month, and year information. The date at the end of the month is automatically adjusted for months with fewer than 31 days, including corrections for leap year. The clock operates in either the 24-hour or 12-hour format with an AM/PM indicator. Two programmable time-of-day/date alarms, a programmable square-wave output, and 16 bytes of SRAM are provided. Address and data are transferred serially through a 2-wire bidirectional bus.

Applications

RTC Complement to the DS32kHz TCXO

Utility Meters

Appliances

Consumer Electronics

Automotive

Features

♦ RTC Counts Seconds, Minutes, Hours, Day, Date,

Month, and Year with Leap-Year Compensation Valid Up to 2100

♦ Two Programmable Alarms

♦ Programmable Square-Wave Output

♦ Operates from a 32.768kHz, 8.192kHz, 60Hz, or

50Hz Digital Clock Signal

♦ 16 Bytes of SRAM

♦ Fast (400kHz) 2-Wire Interface

♦ 1.7V to 5.5V Operation

DS1375

2-Wire Digital Input RTC with Alarm

______________________________________________ Maxim Integrated Products 1

Pin Configuration

Ordering Information

DS1375

SCL CLK

SCA

GND

CPU

+3V

RPU RPU

RPU = t

r/CB

INT

DS32kHz

BAT

GND

SQWINT

Typical Operating Circuit

Rev 0; 4/03

For pricing, delivery, and ordering information, please contact Maxim/Dallas Direct! at 1-888-629-4642, or visit Maxim’s website at www.maxim-ic.com.

PART TEMP RANGE PIN-PACKAGE TOP MARK

DS1375 -40°C to +85°C 6 Thin QFN DS1375

TOP VIEW

CLK

SQW/INT

16V

DS1375

THIN QFN

5 SCL

SDAGND

DS1375

2-Wire Digital Input RTC with Alarm

2 _____________________________________________________________________

ABSOLUTE MAXIMUM RATINGS

RECOMMENDED DC OPERATING CONDITIONS

(VCC= +1.7V to +5.5V, TA= -40°C to +85°C, unless otherwise noted. Typical values are at VCC= 3.3V, TA= +25°C, unless otherwise noted.) (Note 1)

Stresses beyond those listed under “Absolute Maximum Ratings” may cause permanent damage to the device. These are stress ratings only, and functional operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to absolute maximum rating conditions for extended periods may affect device reliability.

Note 1: Limits at -40°C are guaranteed by design and not production tested. Note 2: All voltages are referenced to ground. Note 3: For the CLK pin, input voltages above V

+ 0.3V cause current to flow into the device. The input current must not

exceed the current drawn by the circuit that is connected to V

. Otherwise, current flows out of the DS1375, raising the

voltage level on the VCCbus.

Note 4: V

IL MIN

on the CLK pin can exceed -0.3V as long as the current is limited to less than 1mA.

Note 5: I

CCA

—SCL clocking at max frequency = 400kHz.

Note 6: CLK pin running at 32,768Hz, rise and fall times at 10ns or less. Note 7: Specified with 2-wire bus inactive.

Voltage Range on V

Relative to Ground.............................................-0.3V to +6.0V

Voltage Range on SDA, SCL, and WDS

Relative to Ground....................................-0.3V to V

+ 0.3V

Operating Temperature Range ...........................-40°C to +85°C

Storage Temperature Range .............................-55°C to +125°C

Soldering Temperature .......................................See IPC/JEDEC

J-STD-020A Specification

Supply Voltage V

Timekeeping Voltage V

Input Logic 1 (SDA, SCL) V

Supply Voltage, Pullup (SQW/INT, CLK)

Input Logic 0 V

Input Leakage (SCL, CLK) I I/O Leakage (SDA, SQW/INT)I

SDA Logic 0 Output I

SQW/INT Logic 0 Output I

Active Supply Current I

Standby Current I

PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS

PULLUP

OLSDA

OLSQW

CCA

CCS

(Note 2) 1.7 3.3 5.5 V

(Note 2) 1.3 5.5 V

(Note 2) 0.7 x V

(Notes 2, 3) 5.5 V

(Notes 2, 4) -0.3

VCC > 2V; VOL = 0.4V

VCC < 2V; VOL = 0.2 x V

VCC > 2V; VOL = 0.4V

1.7V < VCC < 2V; VOL = 0.2 x V

1.3V < VCC < 1.7V; VOL = 0.2 x V

(Notes 5, 6) 33 150 µA

(Notes 6, 7) 150 500 nA

-1 +1 µA

+ 0.3 V

+0.3 V

3.0 mA

250 µA

DS1375

2-Wire Digital Input RTC with Alarm

_____________________________________________________________________ 3

Note 8: After this period, the first clock pulse is generated. Note 9: A device must internally provide a hold time of at least 300ns for the SDA signal (see the V

IHMIN

of the SCL signal) to

bridge the undefined region of the falling edge of SCL.

Note 10: The maximum t

HD:DAT

is only met if the device does not stretch the low period (t

LOW

) of the SCL signal.

Note 11: A fast-mode device can be used in a standard-mode system, but the requirement t

SU:DAT

≥ 250ns must then be met. This is automatically the case if the device does not stretch the low period of the SCL signal. If such a device does stretch the LOW period of the SCL signal, it must output the next data bit to the SDA line t

R MAX

+ t

SU:DAT

= 1000 + 250

= 1250ns before the SCL line is released.

Note 12: C

—total capacitance of one bus line in pF.

AC ELECTRICAL CHARACTERISTICS

(VCC= V

CCMIN

to V

CCMAX

, TA= -40°C to +85°C, unless otherwise noted.) (Note 1, Figure 1)

SCL Clock Frequency f

Bus Free Time Between STOP and START Conditions

Hold Time (Repeated) START Condition (Note 8)

Low Period of SCL Clock t

High Period of SCL Clock t

Data Hold Time (Notes 9, 10) t

Data Setup Time (Note 11) t

Start Setup Time t

Rise Time of Both SDA and SCL Signals (Note 12)

Fall Time of Both SDA and SCL Signals (Note 12)

Setup Time for STOP Condition t

Capacitive Load for Each Bus Line (Note 12)

Pulse Width of Spikes that Must be Suppressed by the Input Filter

PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS

SCL

BUF

HD:STA

LOW

HIGH

HD:DAT

SU:DAT

SU:STA

SU:STO

Fast mode 100 400

Standard mode 0 100

Fast mode 1.3

Standard mode 4.7

Fast mode 0.6

Standard mode 4.0

Fast mode 1.3

Standard mode 4.7

Fast mode 0.6

Standard mode 4.0

Fast mode 0 0.9

Standard mode 0 0.9

Fast mode 100

Standard mode 250

Fast mode 0.6

Standard mode 4.7

Fast mode 300

Standard mode

Fast mode 300

Standard mode

Fast mode 0.6

Standard mode 4.7

Fast mode 30 ns

20 + 0.1C

kHz

µs

1000

300

400 pF

µs

CCS

vs. V

DS1375 toc01

VCC (V)

SUPPlY CURRENT (nA)

5.24.74.23.73.22.72.2

100

150

200

250

300

1.7

CCA

vs. V

SUPPLY CURRENT (µA)

100

DS1375 toc02

VCC (V)

5.24.74.23.73.22.72.21.7

Typical Operating Characteristics

(VCC= +3.3V, TA= +25°C, unless otherwise noted.)

DS1375

2-Wire Digital Input RTC with Alarm

4 _____________________________________________________________________

Figure 1. Data Transfer on 2-Wire Serial Bus

Figure 2. Functional Diagram

SDA

BUF

LOW

SCL

STOP START

HD:STA

CLK

SCL

SDA

DIVIDER

DS1375

SERIAL BUS

INTERFACE AND

ADDRESS REGISTER

HD:DAT

HIGH

SU:DAT

8192Hz/4096Hz/1024Hz/1Hz

1Hz

CONTROL

LOGIC

SRAM

REPEATED

START

SU:STA

HD:STA

ALARM AND

REGISTERS

CLOCK AND

CALENDAR REGISTERS

USER BUFFER

CONTROL

(7 BYTES)

MUX/

BUFFER

SQW/INT

SU:STO

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