Rev 1; 1/07
Low-Voltage SPI/3-Wire RTCs with
Trickle Charger
02/DS193
General Description
Features
The low-voltage serial-peripheral interface (SPI™)
DS1390/DS1391 and the low-voltage 3-wire DS1392/
DS1393 real-time clocks (RTCs) are clocks/calendars
that provide hundredths of a second, seconds, min-
utes, 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.
One programmable time-of-day alarm is provided. A
temperature-compensated voltage reference monitors
♦ Real-Time Clock Counts Hundredths of Seconds,
Seconds, Minutes, Hours, Day, Date, Month, and
Year with Leap-Year Compensation Valid Up to
2100
♦ Output Pin Configurable as Interrupt or Square
Wave with Programmable Frequency of
32.768kHz, 8.192kHz, 4.096kHz, or 1Hz
(DS1390/DS1393 Only)
♦ One Time-of-Day Alarm
♦ Power-Fail Detect and Switch Circuitry
♦ Reset Output/Debounced Input (DS1391/DS1393)
♦ Separate SQW and INT Output (DS1392)
♦ Trickle-Charge Capability
♦ SPI Supports Modes 1 and 3 (DS1390/DS1391)
♦ 3-Wire Interface (DS1392/DS1393)
♦ 4MHz at 3.0V and 3.3V
the status of V
and automatically disables the bus
CC
interface and switches to the backup supply if a power
failure is detected. On the DS1390, a single open-drain
output provides a CPU interrupt or a square wave at
one of four selectable frequencies. The DS1391
replaces the SQW/INT pin with a RST output/
debounced input.
The DS1390 and DS1391 are programmed serially
through an SPI-compatible, bidirectional bus. The
DS1392 and DS1393 communicate over a 3-wire serial
bus, and the extra pin is used for either a separate
interrupt pin or a RST output/debounced input.
♦ 1MHz at 1.8V
♦ Three Operating Voltages: 1.8V 5%, 3.0V 10%,
and 2.97 to 5.5V
All four devices are available in a 10-pin µSOP package,
and are rated over the industrial temperature range.
♦ Industrial Temperature Range: -40°C to +85°C
♦ Underwriters Laboratory (UL) Recognized
Applications
Ordering Information
Hand-Held Devices
TYP
OPERATING
VOLTAGE (V)
PIN-
PACKAGE
†
PART
TOP MARK
GPS/Telematics Devices
Embedded Time Stamping
Medical Devices
DS1390U-18+
DS1390U-3+
DS1390U-33+
DS1391U-18+
DS1391U-3+
DS1391U-33+
DS1392U-18+
DS1392U-3+
DS1392U-33+
DS1393U-18+
DS1393U-3+
DS1393U-33+
1.8
3.0
3.3
1.8
3.0
3.3
1.8
3.0
3.3
1.8
3.0
3.3
10 μSOP
10 μSOP
10 μSOP
10 μSOP
10 μSOP
10 μSOP
10 μSOP
10 μSOP
10 μSOP
10 μSOP
10 μSOP
10 μSOP
1390 rr-18
1390 rr-3
1390 rr-33
1391 rr-18
1391 rr-3
1391 rr-33
1393 rr-18
1392 rr-3
1392 rr-33
1393 rr-18
1393 rr-3
1393 rr-33
Typical Operating Circuits and Pin Configurations appear at
end of the data sheet.
Note: All devices are rated for the -40°C to +85°C operating
temperature range.
+Denotes lead-free package.
†A “+” anywhere on the top mark denotes a lead-free/RoHS-
compliant package.
rr = Revision code on second line of top mark.
SPI is a trademark of Motorola, Inc.
______________________________________________ Maxim Integrated Products
1
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.