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PT7C4337
Real-time Clock Module (I
2
C Bus)
Features
Using external 32.768kHz quartz crystal for
PT7C4337
Supports I
2
C-Bus's high speed mode (400 kHz)
Includes time (Hour/Minute/Second) and calendar
(Year/Month/Date/Day) counter functions (BCD
code)
Programmable square wave output signal
Two Time-of-Day Alarms
Oscillator Stop Flag
Operating range: 1.8V to 5.5V
Timekeeping range: 1.2V to 1.8V
Description
The PT7C4337 serial real-time clock is a low-power
clock/calendar with two programmable time-of-day
alarms and a programmable square-wave output.
Address and data are transferred serially via a 2-wire,
bidirectional bus. The clock/calendar provides 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 clock operates in either the
24-hour or 12-hour format with AM/PM indicator.
The device is fully accessible through the serial interface
while VCC is between 1.8V and 5.5V. I
2
C operation is
not guaranteed below 1.8V. Timekeeping operation is
maintained with VCC as low as 1.2V.
Table 1 shows the basic functions of PT7C4337. More
details are shown in section: overview of functions.
Table 1.
Basic functions of PT7C4337
Item
Function
Source
Crystal(32.768KHz)
PT7C4337
External crystal
-
2
1, 4.096k, 8.192k, 32.768k
1
Oscillator
Oscillator enable/disable
Oscillator fail detect
Time
display
12-hour
24-hour
2
Time
Century bit
Time count chain enable/disable
3
4
5
Interrupt
Alarm interrupt output
2-wire I
2
C bus
Programmable square wave output (Hz)
Communication
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PT7C4337
Real-time Clock Module (I
2
C Bus)
Pin Assignment
PT7C4337
1
X1
VCC
8
2
X2
INTA
SQW/INTB
7
SCL
6
3
4
GND
SDA
5
Pin Description
Pin No.
1
2
6
5
Pin
X1
X2
SCL
SDA
Type
I
O
I
I/O
DIP-8、SOIC-8
MSOP8
Description
Oscillator Circuit Input.
Together with X1, 32.768kHz crystal is connected between them.
Or external clock input.
Oscillator Circuit Output.
Together with X1, 32.768kHz crystal is connected between
them. When 32.768kHz external input, X2 must be float.
Serial Clock Input.
SCL is used to synchronize data movement on the I
2
C serial interface.
Serial Data Input/Output.
SDA is the input/output pin for the 2-wire serial interface. The
SDA pin is open-drain output and requires an external pull-up resistor.
Interrupt Output.
When enabled, INTA is asserted low when the time matches the values
set in the alarm registers. This pin is an open-drain output and requires an external pull up
resistor.
Square-Wave/Interrupt Output.
Programmable square-wave or interrupt output signal. It
is an open-drain output and requires an external pull up resistor.
Power.
Primary power for PT7C4337.
Ground.
No Connect.
These pins are not connected internally, but must be grounded for proper
operation.
3
INTA
SQW/I
NTB
VCC
GND
NC
O
7
8
4
/
O
P
P
Maximum Ratings
Storage Temperature ............................................................ -65℃ to +150℃
Ambient Temperature with Power Applied ........................... -40℃ to +85℃
Supply Voltage to Ground Potential (V
CC
to GND) ............... -0.3V to +6.5V
DC Input (All Other Inputs except Vcc & GND)
......................................
-0.3V to (Vcc +0.3V)
DC Output Voltage (SDA, /INTA, /INTB pins)........................................-0.3V to +6.5V
DC Output Current (FOUT) ............................................... -0.3V to (Vcc +0.3V)
Power Dissipation .............................................320mW(depend on package)
Note:
Stresses greater than those listed under
MAXIMUM RATINGS may cause permanent
damage to the device. This is a stress rating
only and functional operation of the device at
these or any other conditions above those
indicated in the operational sections of this
specification is not implied. Exposure to
absolute maximum rating conditions for
extended periods may affect reliability.
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PT7C4337
Real-time Clock Module (I
2
C Bus)
Operating Mode
The amount of current consumed by the PT7C4337 is determined, in part, by the I
2
C interface and oscillator operation. The
following table shows the relationship between the operating mode and the corresponding I
CC
parameter.
V
CC
Operating Mode
Power
2
I C Interface Active
1.8V ≤ V
CC
≤ 5.5V
I
CC
Active (I
CCA
)
2
I C Interface Inactive
1.8V ≤ V
CC
≤ 5.5V
I
CC
Standby (I
CCS
)
2
I C Interface Inactive
1.2V ≤ V
CC
≤ 1.8V
Timekeeping (I
CCTOSC
)
2
I C Interface Inactive, Oscillator Disabled
1.2V ≤ V
CC
≤ 1.8V
Data Retention (I
CCTDDR
)
Recommended Operating Conditions
Part No.
Sym.
V
CC
V
CCT
V
OSC
PT7C4337
V
IH
V
IL
T
A
V
CC
supply voltage
Oscillator start up voltage
SCL, SDA
Input high level
INTA, SQW/INTB
Input low level
Operating temperature
Description
Min
1.8
1.2
1.2
0.7V
CC
-
-0.3
-40
Type
3.3
-
-
-
-
-
-
Max
5.5
1.8
5.5
V
CC
+0.3
5.5
0.3V
CC
85
º
C
V
Unit
DC Electrical Characteristics
Unless otherwise specified, V
CC
= 1.8~5.5V, T
A
= -40 ° to +85 °
C
C
Sym.
V
CC
V
CCT
V
OSC
V
IL1
V
IH1
V
IL2
V
IH2
I
OL
I
IL
I
OZ
Item
Supply voltage
Oscillator voltage
Low-level input voltage
High-level input voltage
Low-level input voltage
High-level input voltage
Low-level output current
Input leakage current
Output current when OFF
V
CC
V
CC
SCL
SCL
X1
X1
SDA, /INTA, /INTB
SCL
SDA, /INTA, /INTB
Pin
Condition
Full operation
Timekeeping (Note 5)
Min
1.8
1.2
1.2
-0.3
0.7V
CC
-
-
3
-1
-1
Typ
Max
Unit
-
5.5
V
-
1.8
-
5.5
V
-
0.3V
CC
V
-
V
CC
+0.3
0.53
-
V
0.53
-
-
-
mA
-
-
1
1
A
A
V
OL
= 0.4V
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PT7C4337
Real-time Clock Module (I
2
C Bus)
Min
-
-
-
-
-
-
Typ
450
-
-
0.6
-
1.0
Max
800
160
100
1.0
150
1.8
Unit
DC Electrical Characteristics
Sym.
Item
Pin
Condition
Unless otherwise specified, V
CC
= 1.3~1.8V, T
A
= -40 ° to +85 °
C
C
V
CC
Note 2, 4, 5
I
CCTOSC
Timekeeping current
V
CC
Note 2,4,5,6
I
CCTDDR
Data retention current
Unless otherwise specified, V
CC
= 1.8~3.6V, T
A
= -40 ° to +85 °
C
C
I
CCA
Active supply current
V
CC
Note 1, 5
I
CCS
Standby current
V
CC
Note 2, 3, 5
Unless otherwise specified, V
CC
= 3.6~5.5V, T
A
= -40 ° to +85 °
C
C
I
CCA
Active supply current
V
CC
Note 1, 5
I
CCS
Standby current
V
CC
Note 2, 3, 5
Note:
1. SCL clocking at max frequency = 400kHz, V
IL
= 0.0V, V
IH
= VCC.
2. Specified with 2-wire bus inactive, V
IL
= 0.0V, V
IH
= VCC.
3. SQW enabled.
4. Specified with the SQW function disabled by setting INTCN = 1.
5. Using recommended crystal on X1 and X2.
6. Crystal oscillator is disabled.
nA
A
A
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PT7C4337
Real-time Clock Module (I
2
C Bus)
Recommended Layout for Crystal
Note:
The crystal, traces and crystal input pins
should be isolated from RF generating signals.
Built-in Capacitors Specifications and Recommended External Capacitors
Symbol
Typ
Unit
X1 to GND
C
G
12
pF
Build-in capacitors
X2 to GND
C
D
12
pF
X1 to GND
C
1
13
pF
Recommended External capacitors for
crystal C
L
=12.5pF
X2 to GND
C
2
13
pF
X1 to GND
C
1
0
pF
Recommended External capacitors for
crystal C
L
=6pF
X2 to GND
C
2
0
pF
Note:
The frequency of crystal can be optimized by external capacitor C
1
and C
2
, for frequency=32.768KHz, C
1
and C
2
should
meet the equation as below:
Cpar + [(C
1
+C
G
)*(C
2
+C
D
)]/ [(C
1
+C
G
)+(C
2
+C
D
)] =C
L
Cpar is all parasitical capacitor between X1 and X2.
C
L
is crystal’s load capacitance.
Parameter
Crystal Specifications
Parameter
Nominal Frequency
Series Resistance
Load Capacitance
Symbol
f
O
ESR
C
L
Min
-
-
-
Typ
32.768
-
6/12.5
Max
-
70
-
Unit
kHz
k
pF
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