R
EM MICROELECTRONIC -
MARIN SA
V3025
Very Low Power 8-Bit 32 kHz RTC Module with Digital
Trimming, User RAM and Battery Switch-over
Description
The V3025 is a low power CMOS real time clock with an
integrated battery switch-over. The standby current is
typically 2.5 µA and the access time is 50 ns. The
interface is a multiplexed address and data 8 bits bus.
Multiplexing of address and data is handled by the input
line
A
/D. There are no busy flags in the V3025, internal
time update cycles are invisible to the user's software.
Time data can be read from the V3025 in 12 or 24 hour
data formats. An external signal puts the V3025 in
standby mode. Even in standby, the V3025 pulls the
IRQ
pin active low on an internal alarm interrupt. Calendar
functions include leap year correction and week number
calculation. The V3025 can be synchronized to an
external 50 Hz signal or to the nearest second or minute.
The integrated battery switch-over supply the real time
clock part by V
DD
as long as V
DD
is higher than V
BAT
.
When V
DD
decreases under V
BAT
, the output
PFO
comes
active and the real clock is supplied by the battery or the
supercap.
Applications
Industrial controllers
Alarm systems with periodic wake up
PABX and telephone systems
Point of sale terminals
Automotive electronics
Personal computers
Features
Built-in quartz with digital trimming
temperature compensation facilities
INTEL and MOTOROLA interface compatibility
15 ns typical access time at 5.0V
1.2 µA typical standby current at 3.0V
Wide supply voltage range, 2.0
≤
V
DD
≤
5.5V
Integrated battery switch-over
Battery voltage range, 2.0
≤
V
BAT
≤
4.0V
No busy state
No external components required
BCD format
Frequency measurements
Time set lock mode
Week number calculation
Clock counts up to 99 years
Leap year correction
12 or 24 hour data format
Output programmable interrupts
Alarm interrupt, programmable up to one month
Timer interrupt, programmable up to 24 hours
Time to 1/100 of a second
To external time reference synchronisation
50 Hz or nearest s/min synchronisation
Power fail input
PFI
Power fail output or Reset output
PFO
Tri-state bus capability when power fail (
PFI
= 0)
User RAM
Temperature range -40 to +85°C
Package SO28
and
Typical Operating Configuration
Pin Assignment
SO28
SYNC
PFI
AD0
AD1
AD2
AD3
A/D
IRQ
V
OUT
V
SS
V
SS
V
SS
V
SS
V
SS
V
BAT
AD7
AD6
AD5
AD4
RD
WR
V3025
CS
PFO
V
DD
V
DD
V
DD
V
DD
V
DD
Fig. 1
Copyright © 2004, EM Microelectronic-Marin SA
1
Fig. 2
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EMMICRO [ EM MICROELECTRONIC - MARIN SA ]
