Datasheet

ManualsBrandsMAXIM INTEGRATED ManualsIntegrated Circuits (ICs)Timer IC t- real time clock Clock/calendar µSOP-10

Detailed Description

The DS1390–DS1394 RTCs are low-power clocks/calen-

dars with alarms. Address and data are transferred seri-

ally through a 4-wire SPI interface for the DS1390 and

DS1391 and through a 3-wire interface for the DS1392,

DS1393, and DS1394. 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 section).

The clocks/calendars provide hundredths of seconds,

seconds, minutes, hours, day, date, month, and year

information. The alarm functions are performed off all

timekeeping registers, 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 corrections for leap year. The clocks

operate in either the 24-hour or 12-hour format with an

AM/PM indicator. All five devices have a built-in tempera-

ture-compensated voltage reference that detects power

failures and automatically switches to the battery supply.

Additionally, the devices can provide trickle charging of

the backup voltage source, with selectable charging resis-

tance and diode voltage drops.

BUS

INTERFACE

LEVEL DETECT,

POWER SWITCH,

WRITE PROTECT,

TRICKLE CHARGER

(DS1390/91/94) DIN

(DS1390/91/94) DOUT

(DS1392/93) I/O

SCLK

GND

BACKUP

(DS1390/91/94) 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 (DS1390/93/94)

CONTROL/STATUS

REGISTERS

ALARM REGISTERS

RST (DS1391)

SQW (DS1392)

DS1390/DS1391/

DS1392/DS1393/DS1394

BUS