DS1307+ Dallas Semiconductor, DS1307+ Datasheet - Page 6

• Manufacturer Part Number: DS1307+
• Description: Clock, Real Time; PDIP; 8 Pins; -0.5 to +7.0 V; 0.7 V (Max.); +0.8 V (Max.)
• Manufacturer: Dallas Semiconductor

Specifications of DS1307+

• Lead Free Status / Rohs Status: RoHS Compliant part Electrostatic Device

PIN DESCRIPTION
DETAILED DESCRIPTION
The DS1307 is a low-power clock/calendar with 56 bytes of battery-backed SRAM. 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 DS1307 operates as a slave device on the I
condition and providing a device identification code followed by a register address. Subsequent registers
can be accessed sequentially until a STOP condition is executed. When V
device terminates an access in progress and resets the device address counter. Inputs to the device will not
be recognized at this time to prevent erroneous data from being written to the device from an out-of-
tolerance system. When V
mode. Upon power-up, the device switches from battery to V
recognizes inputs when V
elements of the serial RTC.
PIN
1
2
3
4
5
6
7
8
SWQ/OUT
NAME
GND
V
SDA
SCL
V
X1
X2
BAT
CC
Connections for Standard 32.768kHz Quartz Crystal. The internal oscillator circuitry is
designed for operation with a crystal having a specified load capacitance (C
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.
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.
Diodes in series between the battery and the V
backup supply is not required, V
(V
circuitry as 1.25 x V
the DS1307 for more than 10 years in the absence of power at +25°C.
Ground
Serial Data Input/Output. SDA is the data input/output for the I
SDA pin is open drain and requires an external pullup resistor.
Serial Clock Input. SCL is the clock input for the I
data movement on the serial interface.
Square Wave/Output Driver. When enabled, the SQWE bit set to 1, the SQW/OUT pin
outputs one of four square-wave frequencies (1Hz, 4kHz, 8kHz, 32kHz). The SQW/OUT
pin is open drain and requires an external pullup resistor. SQW/OUT operates with either
V
Primary Power Supply. 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 V
function continues unaffected by the lower input voltage.
Note: For more information on crystal selection and crystal layout considerations, refer to
Application Note 58: Crystal Considerations with Dallas Real-Time Clocks.
UL recognized to ensure against reverse charging current when used with a lithium
battery. Go to: www.maxim-ic.com/qa/info/ul/.
CC
PF
CC
) voltage at which access to the RTC and user RAM is denied is set by the internal
or V
CC
is greater than 1.25 x V
falls below V
BAT
applied.
CC
is below V
BAT
nominal. A lithium battery with 48mAhr or greater will back up
BAT
TP
, the device switches into a low-current battery-backup
, read and writes are inhibited. However, the timekeeping
2
6 of 15
C bus. Access is obtained by implementing a START
BAT
BAT
must be grounded. The nominal power-fail trip point
. The block diagram in Figure 1 shows the main
FUNCTION
CC
when V
BAT
DS1307 64 x 8, Serial, I
pin may prevent proper operation. If a
2
C interface and is used to synchronize
CC
CC
is greater than V
falls below 1.25 x V
2
C serial interface. The
2
C Real-Time Clock
BAT
L
) of 12.5pF.
+0.2V and
BAT
, the