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PT7C4339/4339C
Real-time Clock Module
Features
Real-Time Clock (RTC) Including Time (Seconds,
Minutes and Hours) and Calendar (Day, Date,
Month and Year with Leap-Year Compensation
Valid Up to 2100) counter functions (BCD code)
Available in a Surface-Mount Package with an
Integrated Crystal (Only for PT7C4339C)
I
2
C Serial Interface supports I
2
C-Bus's high speed
mode (400 kHz)
Programmable square wave output signal, defaults
to 32 kHz on Power-up
Two Time-of-Day Alarms
Oscillator Stop Flag
Automatic Power-Fail Detect and Switch Circuitry
Temperature Range: -40° to +85°
C
C
Package: MSOP-8L and SOIC-8L for PT7C4339
TDFN4x4-8L for PT7C4339C
Description
The PT7C4339 real-time clock is a low-power
clock/calendar device with two programmable time-of-
day alarms and a programmable square-wave output.
Address and data are transferred serially through an I
2
C
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 PT7C4339
has a build-in power-sense circuit that detects power
failures and automatically switch to the backup supply,
maintaining time, date, and alarm operation.
Pin Configuration
PT7C4339
1
PT7C4339C
V
CC
8
1
Applications
X1
NC
NC
8
2
X2
V
BACKUP
SQW/INT
7
2
V
BACKUP
SCL
7
6
3
SCL
6
3
GND
SQW/INT
V
CC
4
GND
SDA
5
4
SDA
5
SOIC-8
MSOP8
DFN4*4-8L
Table1.
Diverse functions of RTC circuits
Item
Source
1
Oscillator
Function
External crystal
PT7C4339
External crystal
2
1, 4.096k, 8.192k, 32.768k
PT7C4339C
Integrated Crystal
2
1, 4.096k, 8.192k, 32.768k
Oscillator enable/disable
Oscillator fail detect
12-hour
Time display
24-hour
2
Time
Century bit
Time count chain enable/disable
3
4
5
6
Interrupt
Alarm interrupt output
Programmable square wave output (Hz)
Communication
Power failure detect
2-wire I
2
C bus
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PT7C4339/4339C
Real-time Clock Module
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Pin Description
Pin No
Pin
4339 4339C
Name
1
2
6
5
/
/
7
4
X1
X2
SCL
SDA
Type
I
O
I
I/O
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. The
pull up voltage may be up to 5.5V regardless of the voltage on V
CC
.
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. The pull up voltage may be up to
5.5V regardless of the voltage on V
CC
.
Secondary Power Supply.
Supply voltage must be held between 1.3V and 3.7V for proper
operation. This pin can be connected to a primary cell, such as a lithium button cell. Additionally,
this pin can be connected to a rechargeable cell or a super cap when used in conjunction with the
trickle-charge feature. Diodes should not be placed in series between the backup source and the
V
BACKUP
input, or improper operation will result. If a backup supply is not required, V
BACKUP
must
be grounded.
Square-Wave/Interrupt Output.
Programmable square-wave or interrupt output signal. It is an
open-drain output and requires an external pull up resistor. The pull up voltage may be up to 5.5V
regardless of the voltage on V
CC
. If not used, this pin may be left unconnected.
Power.
When voltage is applied within normal limits, the device is fully accessible and data can be
written and read. When a backup supply is connected and V
CC
is below V
PF
, reads and writes are
inhibited. The timekeeping and alarm functions operate when the device is powered by V
CC
or
V
BACKUP
.
Ground.
No Connect.
These pins are not connected internally, but must be grounded for proper operation.
3
2
V
BACKU
P
O
7
6
SQW
/INT
O
8
4
/
5
3
1,8
V
CC
GND
NC
P
P
Maximum Ratings
Storage Temperature.................................................................................... -55oC to +125oC
Ambient Temperature with Power Applied..............................................-40oC to +85oC
Supply Voltage to Ground Potential (V
CC
to GND)..................................-0.3V to +6.0V
DC Input (All Other Imputs except V
CC
& GND) ........................... -0.3V to V
CC
+0.3V
DC Output Voltage (SDA, SQW /INT pins) .............................................-0.3V to +6.0V
Power Dissipation ...................................................................320mW(depend on package)
Lead Temperature (soldering, 10s)............................................................................+260 oC
Soldering Temperature (reflow).................................................................................+260 oC
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 condi-
tions above those indicated in the operational sec-
tions of this specification is not implied. Exposure
to absolute maximum rating conditions for extended
periods may affect reliability.
Recommended Operating Conditions
Symbol
V
CC
V
BACKUP
V
IH
V
IL
V
PF
T
A
Supply Voltage
Backup Supply Voltage
Input high level
Input low level
Power-Fail Voltage
Operation Temperature
Description
Min
3.0
1.3
0.7V
CC
-0.3
1.60
-40
Type
3.3
3.0
-
-
1.72
-
Max
5.5
3.7
V
CC
+0.3
0.3V
CC
1.88
85
Unit
V
V
V
V
V
º
C
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PT7C4339/4339C
Real-time Clock Module
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DC Electrical Characteristics
Unless otherwise specified, V
CC
= MIN to MAX, V
BACKUP
=MIN to MAX, T
A
= -40 ° to +85 °
C
C
Item
Input Leakage
I/O Leakage
Sym.
I
LI
I
LO
I
OL1
Pin
SCL
SDA, SQW/INT
SQW/INT
SDA,
Condition
V
IN
=V
CC
or
GND
Min
-1
-1
1.0
1.5
Typ
Max
1
1
Units
μA
μA
mA
mA
3.0
3.0
-
-
Logic0 Out V
OL
= 0.4V; V
CC
> V
CCMIN
I
OL2
Logic 0 Out V
OL
= 0.2V;
V
BACKUP
>= V
BACKMIN
V
CC
Active Current
V
CC
Standby Current(Note 2)
Trickle-Charger Resistor Register10h
= A5h, V
CC
= Typ, V
BACKUP
= 0V
Trickle-Charger Resistor Register10h
= A6h, V
CC
= Typ, V
BACKUP
= 0V
Trickle-Charger Resistor Register10h
= A7h, V
CC
= Typ, V
BACKUP
= 0V
V
BACKUP
Leakage Current
I
OL1
I
CCA
I
CCS
R1
R2
R3
I
BKLKG
SQW/INT
V
CC
absent,
BBSQI=1
(Note 1)
0.25
-
mA
μA
μA
Ω
Ω
Ω
80
40
250
100
150
V
CC
= 3.3V
V
CC
= 5.5V
(Note 3)
200
2000
4000
V
BACKUP
25
100
nA
DC Electrical Characteristics
Unless otherwise specified, V
CC
= 0V, V
BACKUP
=MIN to MAX, T
A
= -40 ° to +85 °
C
C
Item
V
BACKUP
Current, /EOSC=0, SQW Off
V
BACKUP
Current, /EOSC=0, SQW On
V
BACKUP
Current, /EOSC=1
Sym.
I
BKOSC
I
BKSQW
I
BKDR
Condition
Note 4, Note5
Note 4
Note6
Min
Typ
300
400
10
Max
600
900
100
Units
nA
nA
nA
Note:
1. SCL clocking at max frequency = 400 kHz, V
IL
= 0.0V, V
IH
= VCC, trickle charger disabled.
2. Specified with 2-wire bus inactive, V
IL
= 0.0V, V
IH
= VCC, trickle charger disabled.
3. V
CC
must be less than 3.63V if 200Ω resistance is selected.
4. Using recommended crystal on X1 and X2.
5. Specified with the SQW function disabled by setting INTCN = 1.
6. Crystal oscillator is disabled.
2015-08-0008
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Real-time Clock Module
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AC Electrical Characteristics
Sym
V
HM
V
HL
Description
Rising and falling threshold voltage high
Rising and falling threshold voltage low
Value
0.8 V
CC
0.2 V
CC
Unit
V
V
Signal
V
HM
V
LM
t
f
Over the operating range (Figure 1)
Symbol
Item
f
SCL
SCL clock frequency
t
SU;STA
START condition set-up time
t
HD;STA
START condition hold time
t
SU;DAT
Data set-up time (RTC read/write)
t
HD;DAT1
Data hold time (RTC write)
t
HD;DAT2
Data hold time (RTC read)
t
SU;STO
STOP condition setup time
t
BUF
Bus idle time between a START and STOP condition
t
LOW
When SCL = "L"
t
HIGH
When SCL = "H"
t
r
Rise time for SCL and SDA
t
f
Fall time for SCL and SDA
t
SP
*
Allowable spike time on bus
C
B
Capacitance load for each bus line
C
I/O
*
I/O Capacitance (SDA, SCL)
T
OSF
Oscillator Stop Flag (OSF) Delay
* Note:
only reference for design
t
r
Min.
-
0.6
0.6
200
35
0
0.6
1.3
1.3
0.6
-
-
-
-
-
-
Typ.
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
-
Max.
400
-
-
-
-
-
-
-
-
-
0.3
0.3
50
400
10
100
Unit
kHz
s
s
ns
ns
s
s
s
s
s
s
s
ns
pF
pF
ms
S
SCL
t
LOW
f
SCL
t
HIGH
Sr
t
HD;STA
t
SP
P
t
SU;STA
t
BUF
SDA
t
HD;STA
t
SU;DAT
t
HD;DAT
t
SU;STA
t
SU;STO
t
HD;STA
S
Sr
Start condition
Restart condition
P
Stop condition
Figure1 I
2
C Timing
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Real-time Clock Module
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Functional Block Diagram
V
CC
Power Failure Detect
Comparator 1
Alarm 1 Register
(Sec, Min, Hour, Day/Date)
V
BACKUP
X1
32.768
kHz
C
D
Trickle Charger Control
Comparator 2
Alarm 2 Register
(Min, Hour, Day/Date)
OSC
Counter Chain
Time Counter
(Sec,Min,Hour,Day,Date,Month,Year)
X2
“C” version only
C
G
Control Register
Address
Decoder
Address
Register
I /O
Interface
(I
2
C)
Shift Register
SCL
SQW/INT
Interrupt Control
Square Wave Output Control
SDA
Oscillator Circuit
PT7C4339
The PT7C4339 uses an external 32.768 kHz crystal. Table1 specifies several crystal parameters for the external crystal. The
Block Diagram
shows a functional schematic of the oscillator circuit. The startup time is usually less than 1 second when using a
crystal with the specified characteristics.
Table1 Crystal Specifications
Parameter
Symbol
Min
Typ
Max
Unit
Nominal Frequency
f
O
-
32.768
-
kHz
Series Resistance
ESR
-
-
70
k
Load Capacitance
C
L
-
6
-
pF
Note:
The crystal, traces, and crystal input pins should be isolated from RF generating signals.
Clock Accuracy
The accuracy of the clock is dependent upon the accuracy of the crystal and the accuracy of the match between the capacitive
load of the oscillator circuit and the capacitive load for which the crystal was trimmed. Crystal frequency drift caused by
temperature shifts creates additional error. External circuit noise coupled into the oscillator circuit can result in the clock running
fast. Figure 2 shows a typical PC board layout for isolating the crystal and oscillator from noise.
PT7C4339C
The PT7C4339C integrates a standard 32,768Hz crystal in the package. Typical accuracy at nominal VCC and +25° is
C
approximately
±10ppm.
2015-08-0008
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