d1340-33 Maxim Integrated Products, Inc., d1340-33 Datasheet - Page 6

• Manufacturer Part Number: d1340-33
• Description: Ds1340, Ds1340c I?c Rtc With Trickle Charger
• Manufacturer: Maxim Integrated Products, Inc.

I
The DS1340 is a low-power clock/calendar with a trickle
charger. Address and data are transferred serially
through a I
vides seconds, minutes, 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 DS1340
has a built-in power-sense circuit that detects power fail-
ures and automatically switches to the backup supply.
The power-control function is provided by a precise,
temperature-compensated voltage reference and a
comparator circuit that monitors the V
device is fully accessible and data can be written and
read when V
falls below V
from any access. If V
device power is switched from V
6
—
2
8
1
2
3
4
5
6
7
8
PIN
C RTC with Trickle Charger
_____________________________________________________________________
4–13
16
14
15
16
—
—
1
2
3
2
V
C bidirectional bus. The clock/calendar pro-
FT/OUT
CC
NAME
PF
BACKUP
GND
SDA
N.C.
SCL
V
X1
X2
, the internal clock registers are blocked
CC
is greater than V
Connections for a Standard 32.768kHz Quartz Crystal. The internal oscillator circuitry is designed for
operation with a crystal having a specified load capacitance (C
and can optionally be connected to an external 32.768kHz oscillator. The output of the internal oscillator,
X2, is floated if an external oscillator is connected to X1.
Connection for a Secondary Power Supply. For the 1.8V and 3V devices, V
1.3V and 3.7V for proper operation. Diodes placed in series between the supply and the input pin may
result in improper operation. V
This pin can be connected to a primary cell such as a lithium coin cell. Additionally, this pin can be
connected to a rechargeable cell or a super cap when used with the trickle-charge feature. UL recognized
to ensure against reverse charging when used with a lithium battery (www.maxim-ic.com/qa/info/ul).
Ground
Serial Data Input/Output. SDA is the data input/output for the I
and requires an external pullup resistor.
Serial Clock Input. SCL is the clock input for the I
the serial interface.
Frequency Test/Output. This pin is used to output either a 512Hz signal or the value of the OUT bit. When
the FT bit is logic 1, the FT/OUT pin toggles at a 512Hz rate. When the FT bit is logic 0, the FT/OUT pin
reflects the value of the OUT bit. This open-drain pin requires an external pullup resistor, and operates with
either V
P r i m ar y P ow er S up p l y. W hen vol tag e i s ap p l i ed w i thi n nor m al l i m i ts, the d evi ce i s ful l y accessi b l e and d ata
can b e w r i tten and r ead . W hen a b ackup sup p l y i s connected to the d evi ce and V
w r i tes ar e i nhi b i ted . H ow ever , the ti m ekeep i ng functi on conti nues unaffected b y the l ow er i np ut vol tag e.
No Connection. Must be connected to ground.
Detailed Description
PF
is less than V
CC
or V
PF
Power Control
CC
. However, when V
BACKUP
to V
CC
BACKUP
applied.
BACKUP
level. The
BACKUP
when
, the
CC
can be as high as 5.5V on the 3.3V device.
V
the device power is switched from V
when VCC drops below V
maintained from the V
returned to nominal levels (Table 1). After V
above V
Table 1. Power Control
SUPPLY CONDITION
CC
FUNCTION
2
V
V
V
V
C interface and is used to synchronize data movement on
CC
CC
CC
CC
drops below V
V
V
V
V
CC
CC
CC
CC
< V
> V
< V
> V
PF
< V
< V
> V
> V
, read and write access is allowed t
BACKUP
BACKUP
BACKUP
BACKUP
PF
PF
PF
PF
2
,
,
,
,
C serial interface. The SDA pin is open drain
L
) of 12.5pF. X1 is the input to the oscillator
PF
. If V
BACKUP
BACKUP
READ/WRITE
PF
BACKUP
ACCESS
is greater than V
C C
Yes
Yes
No
No
Pin Description
must be held between
i s b el ow V
source until V
. The registers are
CC
T P
to V
, r ead s and
POWERED
CC
REC
BACKUP
BACKUP
V
V
V
V
BY
returns
BAT
.
CC
CC
CC
CC
is
,