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DS1340Z-18

P1-P3P4-P6P7-P9P10-P12P13-P14
DS1340
I
2
C RTC with Trickle Charger
4 _____________________________________________________________________
POWER-UP/POWER-DOWN CHARACTERISTICS
(T
A
= -40°C to +85°C) (Figure 2)
PARAMETER
SYMBOL
CONDITIONS
MIN TYP MAX
UNITS
Recovery at Power-Up t
REC
(Note 17) 2 ms
V
CC
Fall Time; V
PF(MAX)
to
V
PF(MIN)
t
VCCF
300
µs
V
CC
Rise Time; V
PF(MIN)
to
V
PF(MAX)
t
VCCR
0µs
WARNING: Under no circumstances are negative undershoots, of any amplitude, allowed when device is in battery-backup mode.
Note 1: Limits at -40°C are guaranteed by design and not production tested.
Note 2: After this period, the first clock pulse is generated.
Note 3: A device must internally provide a hold time of at least 300ns for the SDA signal (referred to as the V
IH(MIN)
of the SCL
signal) to bridge the undefined region of the falling edge of SCL.
Note 4: The maximum t
HD:DAT
only has to be met if the device does not stretch the low period (t
LOW
) of the SCL signal.
Note 5: A fast-mode device can be used in a standard-mode system, but the requirement t
SU:DAT
≥ to 250ns must be met. This
is automatically the case if the device does not stretch the low period of the SCL signal. If such a device does stretch the
low period of the SCL signal, it must output the next data bit to the SDA line t
R MAX
+ t
SU:DAT
= 1000 + 250 = 1250ns
before the SCL line is released.
Note 6: C
B
—total capacitance of one bus line in pF.
Note 7: The parameter t
OSF
is the period of time the oscillator must be stopped for the OSF flag to be set over the 0V ≤ V
CC
≤
V
CCMAX
and 1.3V ≤ V
BAT
≤ 3.7V range.
Note 8: All voltages are referenced to ground.
Note 9: Measured at V
CC
= typ, V
BACKUP
= 0V, register 08h = A5h.
Note 10: The use of the 250Ω trickle-charge resistor is not allowed at V
CC
> 3.63V and should not be enabled.
Note 11: Measured at V
CC
= typ, V
BACKUP
= 0V, register 08h = A6h.
Note 12: Measured at V
CC
= typ, V
BACKUP
= 0V, register 08h = A7h.
Note 13: I
CCA
—SCL clocking at max frequency = 400kHz.
Note 14: Specified with I
2
C bus inactive.
Note 15: Measured with a 32.768kHz crystal attached to the X1 and X2 pins.
Note 16: Limits at +25°C are guaranteed by design and not production tested.
Note 17: This delay applies only if the oscillator is enabled and running. If the oscillator is disabled or stopped, no power-up delay
occurs.
SDA
SCL
t
HD:STA
t
LOW
t
HIGH
t
R
t
F
t
BUF
t
HD:DAT
t
SU:DAT
REPEATED
START
t
SU:STA
t
HD:STA
t
SU:STO
t
SP
STOP START
Figure 1. Data Transfer on I
2
C Serial Bus
DS1340
I
2
C RTC with Trickle Charger
_____________________________________________________________________ 5
OUTPUTS
V
CC
V
PF(MAX)
INPUTS
HIGH-Z
RST
DON'T CARE
VALID
RECOGNIZED
RECOGNIZED
VALID
V
PF(MIN)
t
RST
t
RPU
t
R
t
F
V
PF
V
PF
Figure 2. Power-Up/Power-Down Timing
I
CCSA
vs. V
CC
FT = 0
DS1340 toc01
V
CC
(V)
SUPPLY CURRENT (µA)
5.04.54.03.53.02.52.01.5
50
100
150
200
250
0
1.0 5.5
25
50
75
100
125
150
0
I
CCS
vs. V
CC
FT = 0
DS1340 toc02
V
CC
(V)
SUPPLY CURRENT (µA)
5.04.54.03.53.02.52.01.51.0 5.5
-1.8V
-3.0V
-3.3V
I
BACKUP1
(FT = 0) vs. V
BACKUP
DS1340 toc03
450
500
550
600
650
700
750
800
850
400
V
BACKUP
(V)
SUPPLY CURRENT (nA)
5.04.54.03.53.02.52.01.51.0 5.5
Typical Operating Characteristics
(V
CC
= +3.3V, T
A
= +25°C, unless otherwise noted.)
I
BACKUP2
(FT = 1) vs. V
BACKUP
DS1340 toc04
450
500
550
600
650
700
750
800
850
400
V
BACKUP
(V)
SUPPLY CURRENT (nA)
5.04.54.03.53.02.52.01.51.0 5.5
FT vs. V
BACKUP
DS1340 toc06
V
BACKUP
(V)
FREQUENCY (Hz)
5.04.51.5 2.0 2.5 3.53.0 4.0
511.9965
511.9970
511.9975
511.9980
511.9985
511.9990
511.9995
512.0000
511.9960
1.0 5.5
I
BACKUP3
vs. TEMPERATURE
DS1340 toc05
TEMPERATURE (°C)
SUPPLY CURRENT (nA)
6040-20 0 20
500
550
600
650
700
750
800
850
-40 80
V
BACKUP
= 3.0V
DS1340
Detailed Description
The DS1340 is a low-power clock/calendar with a trickle
charger. Address and data are transferred serially
through a I
2
C bidirectional bus. The clock/calendar pro-
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.
Power Control
The power-control function is provided by a precise,
temperature-compensated voltage reference and a
comparator circuit that monitors the V
CC
level. The
device is fully accessible and data can be written and
read when V
CC
is greater than V
PF
. However, when V
CC
falls below V
PF
, the internal clock registers are blocked
from any access. If V
PF
is less than V
BACKUP
, the
device power is switched from V
CC
to V
BACKUP
when
V
CC
drops below V
PF
. If V
PF
is greater than V
BACKUP
,
the device power is switched from V
CC
to V
BACKUP
when VCC drops below V
BACKUP
. The registers are
maintained from the V
BACKUP
source until V
CC
is
returned to nominal levels (Table 1). After V
CC
returns
above V
PF
, read and write access is allowed t
REC
.
I
2
C RTC with Trickle Charger
6 _____________________________________________________________________
Pin Description
PIN
8
16
NAME
FUNCTION
1
—
X1
2
—
X2
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
L
) of 12.5pF. X1 is the input to the oscillator
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.
3
14 V
BACKUP
Connection for a Secondary Power Supply. For the 1.8V and 3V devices, V
BACKUP
must be held between
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
BACKUP
can be as high as 5.5V on the 3.3V device.
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).
4
15
GND Ground
5
16
SDA
Serial Data Input/Output. SDA is the data input/output for the I
2
C serial interface. The SDA pin is open drain
and requires an external pullup resistor.
6
1
SCL
Serial Clock Input. SCL is the clock input for the I
2
C interface and is used to synchronize data movement on
the serial interface.
7
2 FT/OUT
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
CC
or V
BACKUP
applied.
8
3
V
CC
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
C C
i s b el ow V
T P
, r ead s and
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.
—
4–13
N.C. No Connection. Must be connected to ground.
SUPPLY CONDITION
READ/WRITE
ACCESS
POWERED
BY
V
CC
< V
PF
,
V
CC
< V
BACKUP
No V
BAT
V
CC
< V
PF
,
V
CC
> V
BACKUP
No V
CC
V
CC
> V
PF
,
V
CC
< V
BACKUP
Yes V
CC
V
CC
> V
PF
,
V
CC
> V
BACKUP
Yes V
CC
Table 1. Power Control
P1-P3P4-P6P7-P9P10-P12P13-P14

DS1340Z-18

Mfr. #:
Buy DS1340Z-18
Manufacturer:
Maxim Integrated
Description:
Real Time Clock I2C RTC w/Trickle Charger
Lifecycle:
New from this manufacturer.
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