PT7C433833A
Real-time Clock Module (I2C Bus)
Features
Using
external 32.768kHz quartz crystal
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
56-byte,
battery-backed, nonvolatile (NV) RAM for data
storage
Automatic
power-fail detect and switch circuitry of battery
backup
UL
Recognized: E348121
Description
The PT7C433833A serial real-time clock is a low-power
clock/calendar with a programmable square-wave output and
56 bytes of nonvolatile RAM.
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 PT7C4338 series have a built-in power sense circuit that
detects power failures and automatically switches to the
battery supply.
Table 1 shows the basic functions of PT7C4338. More details
are shown in section: overview of functions.
Table 1.
Basic functions of PT7C4338
Item
Function
Source: Crystal: 32.768kHz
1
Oscillator
Oscillator enable/disable
Oscillator fail detect
2
3
4
5
6
Time
Alarm interrupt
Programmable square wave output (Hz)
RAM
Battery backup
Time display
Century bit
12-hour
24-hour
PT7C4338
-
-
1, 4.096k, 8.192k, 32.768k
568
PT7C433833A
Document Number DS40364 Rev 1-2
www.diodes.com
January 2018
© Diodes Incorporated
1
PT7C433833A
Pin Assignment
PT7C4338
1
X1
X2
VBAT
GND
VCC
SQW/OUT
SCL
SDA
8
2
7
3
6
4
5
SOIC-8
MSOP-8
Pin Description
Pin no.
1
2
6
5
7
Pin
X1
X2
SCL
SDA
SQW/OUT
Type
I
O
I
I/O
O
Description
32.768kHz Crystal Connections.
The internal oscillator circuitry is designed for operation with
a crystal having a specified load capacitance (CL) of 12.5pF. Pin X1 is the input to the oscillator
and can optionally be connected to an external 32.768kHz oscillator. The output of the internal
oscillator, pin X2, is floated if an external oscillator is connected to pin X1. An external
32.768kHz oscillator can also drive the PT7C4338. In this configuration, the X1 pin is connected
to the external oscillator signal and the X2 pin is floated.
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.
Square-Wave/Output Driver.
When enabled and the SQWE bit set to 1, the SQW/OUT pin
outputs one of four square-wave frequencies (1Hz, 4kHz, 8kHz, 32kHz). It is open drain and
requires an external pull up resistor. Operates with either VCC or VBAT applied.
Supply Voltage.
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 to the device and VCC is
below VPF, reads and writes are inhibited. However, the timekeeping function continues
unaffected by the lower input voltage.
+3V Battery Input.
Backup supply input for any standard 3V lithium cell or other energy
source. Battery voltage must be held between the minimum and maximum limits for proper
operation. If a backup supply is not required, VBAT must be grounded.
UL
recognized to ensure
against reverse charging when used with a lithium battery.
Ground.
DC power is provided to the device on these pins. VCC is the primary power input.
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 to the device and VCC is below VPF, reads
and writes are inhibited. However, the timekeeping function continues unaffected by the lower
input voltage.
8
VCC
P
3
VBAT
P
4
GND
P
PT7C433833A
Document Number DS40364 Rev 1-2
www.diodes.com
January 2018
© Diodes Incorporated
2
PT7C433833A
Function Block
Maximum Ratings
Storage Temperature................................................................................................................... -55oCto +125oC
Junction Temperature
...............................................................................
+125
o
C Max
Supply Voltage to Ground Potential (Vcc to GND) ........................................................-0.3V to +6.5V
DC Input (All Other Inputs except Vcc & GND)..............................................................-0.3V to +6.5V
DC Output Voltage (SDA, /INTA, /INTB pins) ................................................................ -0.3V to +6.5V
DC Output Current (FOUT)..................................................................................................... -0.3V to (V
cc
+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.
(V
CC
= V
CC(MIN)
to V
CC(MAX)
, T
A
= -40
°
C to +85
°
C, unless otherwise noted. Typical values are at T
A
= +25
°
C, unless otherwise
noted.)
Symbol
Parameter
Conditions
Min.
Typ.
Max.
Unit
V
CC
Supply Voltage
PT7C433833A
2.7
3.3
5.5
V
IH
Logic 1
Note 2
0.7 * V
CC
-
V
CC
+ 0.3
V
IL
Logic 0
Note 2
-0.3
-
+0.3 * V
CC
V
V
PF
Power-Fail Voltage
PT7C433833A
1.5
1.75
2.0
V
BAT
V
BAT
Battery Voltage
Note 2
1.3
3.0
3.7
Note 1:
Limits at -40°C are guaranteed by design and not production tested.
Note 2:
All voltages are referenced to ground.
Recommended Operating Conditions
PT7C433833A
Document Number DS40364 Rev 1-2
www.diodes.com
January 2018
© Diodes Incorporated
3
PT7C433833A
DC Electrical Characteristics
(V
CC
= V
CC(MIN)
to V
CC(MAX)
, T
A
= -40
°
C to +85
°
C, unless otherwise noted. Typical values are at V
CC
= 3.3V, T
A
= +25
°
C, unless
otherwise noted.)
Symbol
Parameter
Conditions
Min.
Typ.
Max.
Unit
V
BAT
V
BAT
Battery Voltage
Note 2
1.3
-
3.7
V
I
LI
Input Leakage
Note 3
-1
-
1
μA
I
LO
I/O Leakage
Note 4
-1
-
1
μA
V
CC
> =2V; V
OL
= 0.4V
3.0
-
-
I
OLSDA
SDA Logic 0 Output
mA
V
CC
< 2V; V
OL
= 0.2 V
CC
3.0
-
-
V
CC
> =2V; V
OL
= 0.4V
1.0
-
-
mA
I
OLSQW
SQW/OUT Logic 0 Output
1.3V < V
CC
< 2V; V
OL
= 0.2 V
CC
250
-
-
μA
I
CCA
Active Supply Current (Note 5)
PT7C433833A
-
40
120
μA
I
CCS
Standby Current (Note 6)
PT7C433833A
-
30
100
μA
I
BATLKG
V
BAT
Leakage Current (V
CC
Active) -
-
10
100
nA
(V
CC
= 0V, T
A
= -40
°
C to +85
°
C, unless otherwise noted. Typical values are at V
BAT
= 3.0V, T
A
= +25
°
C, unless otherwise noted.)
Symbol
Parameter
Min.
Typ.
Max.
Unit
I
BATOSC1
V
BAT
Current (OSC ON); V
BAT
=3.7V, SQW/OUT OFF (Note 7)
-
350
1000
nA
V
BAT
Current (OSC ON); V
BAT
=3.7V, SQW/OUT ON (32kHz) (Note
-
400
1200
I
BATOSC2
nA
7)
V
BAT
Data-Retention Current (OSC OFF); V
BAT
=3.7V (Note 7)
-
-
300
I
BATDAT
nA
Note 1:
Limits at -40°C are guaranteed by design and not production tested.
Note 2:
All voltages are referenced to ground.
Note 3:
SCL only.
Note 4:
SDA and SQW/OUT.
Note 5:
ICCA------SCL clocking at max frequency = 400 kHz.
Note 6:
Specified with the I2C bus inactive.
Note 7:
Measured with a 32.768 kHz crystal attached to X1 and X2.
AC Electrical Characteristics
Sym
V
HM
V
HL
Description
Rising and falling threshold voltage high
Rising and falling threshold voltage low
Value
0.7 V
CC
0.3 V
CC
Unit
V
V
Measurement level
Signal
V
HM
V
LM
t
f
t
r
PT7C433833A
Document Number DS40364 Rev 1-2
www.diodes.com
January 2018
© Diodes Incorporated
4
PT7C433833A
AC Electrical Characteristics
(T
A
= -40℃ to +85℃) (Note 1)
Symbol
f
SCL
t
BUF
t
HD:STA
t
LOW
t
HIGH
t
SU:STA
t
HD:STA
t
SU:STA
t
r
t
f
t
SU:STO
C
B
C
I/O
t
OSF
Parameter
SCL Clock Frequency
Bus Free Time Between STOP and
START condition
Hold Time (Repeated) START
Condition
LOW Period of SCL Clock
HIGH Period of SCL Clock
Setup Time of Repeated START
Condition
Data Hold Time
Data Setup Time
Rise Time of Both SDA and SCL
Signals (Note 6)
Fall Time of Both SDA and SCL
Signals
Setup Time for STOP Condition
Capacitance Load for Each Bus Line
I/O Capacitance (SDA, SCL)
Oscillator Stop Flag (OSF) Delay
Conditions
-
-
Note 2
-
-
-
Note3,4
Note5
Fast mode
Standard mode
Note6
-
Note 6
Note 1
Note 7
Min.
-
1.3
0.6
1.3
0.6
0.6
0
100
-
-
-
0.6
-
-
-
Typ.
-
-
-
-
-
-
-
-
-
-
-
-
-
-
100
Max.
400
-
-
-
-
-
0.9
-
300
1000
300
-
400
10
-
Unit
kHz
μs
μs
μs
μs
μs
μs
ns
ns
ns
μs
pF
pF
ms
Note 1:
Limits of full temperature are guaranteed by design not production test.
Note 2:
After this period, the first clock pulse is generated. A limit of min value at fast mode is 4.0us in UM10204 I2C-bus specification.
Note 3:
A device must internally provide a hold time of at least 300ns for the SDA signal (referred to the V
IHMIN
of the SCL signal) to bridge the undefined region
of the falling edge of SCL.
Note 4:
The maximum t
HD:DAT
need only 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 then 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 time period the oscillator must be stopped for the OSF flag to be set over the voltage range of 0.0V
≤
V
CC
≤
V
CC MAX
and 1.3V
≤
V
BAT
≤
3.7V.
Timing Diagram
PT7C433833A
Document Number DS40364 Rev 1-2
www.diodes.com
January 2018
© Diodes Incorporated
5
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