Rainbow-electronics DS1393 Instrukcja Użytkownika Pobierz pdf (Strona 11)

Detailed Description

The DS1390/DS1391/DS1392/DS1393 RTCs are low-

power clocks/calendars with alarms. Address and data

are transferred serially through a 4-wire SPI interface

for the DS1390 and DS1391 and through a 3-wire inter-

face for the DS1392 and DS1393. The clocks/calendars

provide hundredths of seconds, seconds, minutes,

hours, day, date, month, and year information. The

alarm functions are performed off all timekeeping regis-

ters, allowing the user to set high resolution alarms. The

date at the end of the month is automatically adjusted

for months with fewer than 31 days, including correc-

tions for leap year. The clocks operate in either the 24-

hour or 12-hour format with an AM/PM indicator. All four

devices have a built-in temperature-compensated volt-

age reference that detects power failures and automati-

cally switches to the battery supply. Additionally, the

devices can provide trickle charging of the backup

voltage source, with selectable charging resistance

and diode voltage drops.

Operation

The DS1390/DS1391 operate as a slave device on the

SPI serial bus. The DS1392/DS1393 operate using a

3-wire synchronous serial bus. Access is obtained by

selecting the part by the CS pin (CE on DS1392/

DS1393) and clocking data into/out of the part using

the SCLK and DIN/DOUT pins (I/O on DS1392/

DS1393). Multiple-byte transfers are supported within

one CS low period (see the SPI Serial-Data Bus sec-

tion). The devices are fully accessible and data can be

written and read when V

is greater than V

DS1390/DS1391/DS1392/DS1393

Low-Voltage SPI/3-Wire RTCs with

Trickle Charger

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Functional Diagram

BUS

INTERFACE

LEVEL DETECT,

POWER SWITCH,

WRITE PROTECT,

TRICKLE CHARGER

32,768Hz

CRYSTAL

OSCILLATOR

(DS1390/91) DIN

(DS1390/91) DOUT

(DS1392/93) I/O

SCLK

GND

BACKUP

(DS1390/91) CS

(DS1392/93) (CE)

SQUARE-WAVE RATE

SELECTOR, INT, MUX,

RST OUTPUT

HUNDREDTHS-OF-

SECONDS

GENERATOR

REAL-TIME CLOCK

WITH HUNDREDTHS

OF SECONDS

TRICKLE REGISTER

SQW/INT (DS1390/93)

CONTROL/STATUS

REGISTERS

ALARM REGISTERS

RST (DS1391/93)

SQW (DS1392)

DS1390/DS1391/

DS1392/DS1393

1 2 ... 6 7 8 9 10 11 12 13 14 15 16 ... 23 24

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