R
EM MICROELECTRONIC -
MARIN SA
V3021
Ultra Low Power 1-Bit 32 kHz RTC
Description
The V3021 is a low power CMOS real time clock. Data is
transmitted serially as 4 address bits and 8 data bits, over
one line of a standard parallel data bus. The device is
accessed by chip select (
CS ) with read and write control
timing provided by either
RD
and
WR
pulse (Intel CPU)
or DS with advanced R/
W
(Motorola CPU). Data can
also be transmitted over a conventional 3 wire serial
interface having CLK, data I/O and strobe. The V3021
has no busy states and there is no danger of a clock
update while accessing.
Supply current is typically
800 nA at V
DD
= 3.0V. Battery operation is supported by
complete functionality down to 2.0V. The oscillator is
typically 0.3 ppm/V.
Features
Supply current typically 800 nA at 3V
50 ns access time with 50 pF load capacitance
Fully operational from 2.0V to 5.5V
No busy states or danger of a clock update while
accessing
Serial communication on one line of a standard
parallel data bus or over a conventional 3 wire serial
interface
Interface compatible with both Intel and Motorola
Seconds, minutes, hours, day of month, month, year,
week day and week number in BCD format
Leap year and week number correction
Time set lock mode to prevent unauthorized setting of
the current time or date
Oscillator stability 0.3 ppm / volt
No external capacitor needed
Frequency measurement and test modes
Temperature range: -40°C to +85°C
On request extended temperature range, -40°C to
+125°C
Packages DIP8 and SO8
Applications
Utility meters
Battery operated and portable equipment
Consumer electronics
White/brown goods
Pay phones
Cash registers
Personal computers
Programmable controller systems
Data loggers
Automotive systems
Typical Operating Configuration
or R/
Pin Assignment
or
CPU
SO8
XI
XO
Address
Decoder
V
DD
WR
V3021
CS
RD
CS
V
SS
XI
V3021
XO
I/O
Address Bus
RD
WR
I/O
Data Bus
Fig. 2
CS
RD
WR
RAM
Fig. 1
Copyright © 2005, EM Microelectronic-Marin SA
1
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