Data Sheet
PT7C43390
2-Wire Real-time Clock Module
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Product Features
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Low current consumption: 0.25 µA typ. (V
DD
=3.0 V,
T
A
= 25°C)
Wide operating voltage range: 1.3 to 5.5 V
Minimum time keeping operation voltage: 1.1 V
Built-in clock adjustment function
Built-in free user register
2-wire (I2C-BUS) CPU interface
Built-in alarm interrupter
Built-in flag generator at power down or power on
Auto calendar up to the year 2099, automatic leap
year calculation function
Built-in constant voltage circuit
Built-in 32 kHz crystal oscillator circuit (Cd built in,
Cg external)
Lead free Package: 8-pin SOIC, 8-pin TSSOP
Product Description
The PT7C43390 is low-current consumption 2-wire
CMOS real-time clock IC that features a wide operating
voltage range(1.3V to 5.5V) and can be driven on a
variety of supply voltages, from a main supply to a
backup supply. The time keeping current consumption
of 0.25µA and minimum time keeping operation voltage
of 1.1V enable greatly increased battery duration.
In a system that operates on a backup battery, the
free register incorporated in the real-time clock can be
used for the user backup memory function. The user
register can hold data on a supply voltage as low as
1.2V(min.), so the data stored in the register before the
main power supply was cut can be called any time after
the voltage is restored.
This product also includes a clock adjustment
function that enables wide-ranging correction of
deviation in the frequency of the crystal oscillator at a
minimum resolution of 1 ppm. Also, by combining this
Package
Lead free 8-Pin SOIC
Lead free 8-Pin TSSOP
function with a temperature sensor, the clock adjustment
value can be set in accordance with changes in the
temperature, which makes it possible to realize a clock
function that retains a high degree of accuracy regardless
of temperature variation.
Table 1 shows the basic functions of PT7C43390.
More details are shown in section: Overview of
Functions.
Ordering Information
Part Number
PT7C43390WE
PT7C43390LE
Table 1.
Basic functions of PT7C43390
Item
1
2
3
4
5
6
7
8
Crystal
12-hour
Time
Time display
24-hour
Interrupt
Alarm interrupt output
Programmable square wave output (Hz)
2-wire I
2
C bus
Communication
Burst mode
IC test mode
Control
Power-on detector
Power supply voltage detector
Clock calibratoin
Free register acess
Oscillator
Function
Source
*
PT7C43390
√
√
√
√2
1Hz,2Hz,4Hz,8Hz,16Hz,32kHz
√
√
√
√
√
√
√
PT0280(11/07)
1
Ver: 0
Data Sheet
PT7C43390
2-Wire Real-time Clock Module
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Pin Assignment
Pin Description
Pin no.
1
2
3
4
5
Pin
INT1
XOUT
XIN
GND
INT2
Description
Interrupt 1 signal output pin
Depending on the mode set by INT1 register_1 and the status
register, it outputs low or a clock when the time is reached. It is
disabled by rewriting the status register.
Crystal oscillator connect pin
(32,768 Hz)
(Cd built in, Cg external)
Negative power supply pin
(GND)
Interrupt
2 signal output pin
Depending on the mode set by INT1 register_2 and the status
register, it outputs low or clock when time is reached. It is disabled
by rewriting the status register.
Serial clock input pin
Since signal processing is done on the SCL signal rising/ falling
edge, give great care to the rising/falling time and comply strictly
with the specifications.
Serial data I/O pin
Normally, it is pulled up to the VDD voltage by a resistor and
connected with another open-drain output or open-collector output
device via a wired-OR connection.
Positive power supply pin
Configuration
Nch open-drain output (no
protective diode on the
side of VDD)
-
-
Nch open-drain output (no
protective diode on the
side of VDD)
CMOS input (no
protective diode on the
side of VDD)
Nch open-drain output (no
protective diode on the
side of VDD)
CMOS input
-
6
SCL
7
8
SDA
VDD
PT0280(11/07)
2
Ver: 0
Data Sheet
PT7C43390
2-Wire Real-time Clock Module
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Function Block
Function Description
Overview of Functions
Clock function
CPU can read or write data including the year (last two digits), month, date, day, hour, minute, and second. Any (two-digit) year
that is a multiple of 4 is treated as a leap year and calculated automatically as such until the year 2099.
Alarm function
This device has two alarm system (Alarm 1 and Alarm 2) that outputs interrupt signals from INT1 or INT2 to CPU when the date,
day of the week, hour, minute or second correspond to the setting. Each of them may output interrupt signal separately at a
specified time. The alarm is be selectable between on and off for matching alarm or repeating alarm.
Programmable square wave output
Square wave output at pin 1 or pin 5. Six frequencies are selectable: 1, 2, 4, 8, 16, 32.768kHz.
Interface with CPU
For PT7C43390:
2-wire I
2
C interface.
Calibration function
With the calibration bits properly set, the accuracy can be improved to better than ±2 ppm at 25°C.
PT0280(11/07)
3
Ver: 0
Data Sheet
PT7C43390
2-Wire Real-time Clock Module
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Registers
Allocation of registers
Command
C
C
C
Description
2
1
0
0
0
0
0
0
1
Status register_1 access
Status register_2 access
Data
B7
POC*
4
TEST*
5
B6
BLD*
4
INT2A
E
Y40
*
6
*
6
*
6
AM/PM
m40
s20
AM/PM
m40
s20
*
6
AM/PM
m40
SC*
7
*
6
AM/PM
m40
SC*
7
V6
F6
B5
INT2*
3
INT2M
E
Y20
*
6
D20
*
6
H20
m20
s20
H20
m20
s20
*
6
H20
m20
SC*
7
*
6
H20
m20
SC*
7
V5
F5
B4
INT1*
3
INT2F
E
Y10
M10
D10
*
6
H10
m10
s10
H10
m10
s10
*
6
H10
m10
16Hz
*
6
H10
m10
16Hz
V4
F4
B3
SC1*
2
B2
SC0*
2
INT1A
E
Y4
M4
D4
W4
H4
m4
s4
H4
m4
s4
W4
H4
m4
4Hz
W4
H4
m4
4Hz
V2
F2
B1
12/24
INT1M
E
Y2
M2
D2
W2
H2
m2
s2
H2
m2
s2
W2
H2
m2
2Hz
W2
H2
m2
2Hz
V1
F1
B0
RESET*
1
32kE
Y8
M8
D8
*
6
H8
m8
s8
H8
m8
s8
*
6
H8
m8
8Hz
*
6
H8
m8
8Hz
V3
F3
INT1FE
Y1
M1
D1
W1
H1
m1
s1
H1
m1
s1
W1
H1
m1
1Hz
W1
H1
m1
1Hz
V0
F0
0
1
0
Real-time data 1 access
(year data to second
data)
Real-time data 2 access
(hour data to second
data)
INT1 register_1 access
(alarm time 1)
(INT1AE=1,INT1ME=0
INT1FE=0)
INT1 register_1 access
(frequency duty setting)
(INT1ME=0,INT1FE=1
)
INT1 register_2 access
(alarm time 2)
(INT2AE=1,INT2ME=0
INT2FE=0)
INT1 register_2 access
(frequency duty setting)
(INT2ME=0,INT2FE=1
)
Clock adjustment
register access
Free register access
0
1
1
Y80
*
6
*
6
*
6
*
6
*
6
*
6
*
6
*
6
*
6
A1WE
A1HE
A1mE
SC*
7
A2WE
A2HE
A2mE
SC*
7
V7
F7
1
0
0
1
0
1
1
1
1
1
0
1
Caution:
*1. Write-only flag. By writing “1” to this register, the IC is reset.
*2. Scratch bit. R/W-enabled register that can be freely used by users.
*3. Read-only flag. It is cleared when read. It is valid only when the alarm is set.
*4. Read-only flag. “POC” is set to “1” when power is applied. It is cleared when read. For the “BLD”, refer to “Power Supply Voltage
Detector”.
*5. For IC testing. Normally set this register to “0”.
*6. No effect by writing. It is “0” when read.
*7. This is a R/W-enabled register that does not affect interrupts.
PT0280(11/07)
4
Ver: 0
Data Sheet
PT7C43390
2-Wire Real-time Clock Module
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Register configuration
Real-time data register
The real-time data register is a 56-bit register that stores the BCD code of the year, month, day, day of week, hour, minute, and
second data. Any read/write operation performed by the real-time data access command transmits or receives the data from the
LSB which is the first digit of the year.
1.
Year data (00 to 99)
Sets the lower two digits of the Western Calendar
Year (00 to 99) and links together with the auto
calendar feature until 2099.
Month data (01 to 12)
The count value is automatically changed by the auto
calendar feature.
1 to 31: 31-day months (1, 3, 5, 7, 8, 10, 12)
1 to 30: 30-day months (4, 6, 9, 11)
1 to 29: Feb. (leap year)
1 to 28: Feb. (common year)
Day data (01 to 31)
Day of week data (00 to 06)
A septenary counter. Set it so that it corresponds to
the day of the week.
Hour data (00 to 23 or 00 to 11)
AM/PM
For a 12-hour expression, write 0 and 1 for AM and
PM, respectively.
For a 24-hour expression, either 0 or 1 can be written. 0
is read when the hour data is from 00 to 11, and 1 is
read when from 12 to 23.
Minute data (00 to 59)
Second data (00 to 59)
PT0280(11/07)
5
Ver: 0
FPGA/CPLD
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