Pin descriptions, Figure 3. recommended layout for crystal – Rainbow Electronics DS1672 User Manual
Page 6
DS1672
6 of 12
PIN DESCRIPTIONS
PIN
NAME
FUNCTION
1, 2
X1, X2
32.768kHz Crystal Pins. These signals are connections for a standard
32.768kHz quartz crystal. The internal oscillator circuitry is designed for
operation with a crystal having a specified load capacitance (CL) of 6pF. (See
note)
3
V
BACKUP
Power Supply Input. Battery input for any standard 3V lithium cell or other
energy source. Battery voltage must be held between 1.3V and 3.63V for
proper operation. UL recognized to ensure against reverse charging current
when used in conjunction with a lithium battery (charger disabled). See
“Conditions of Acceptability” at
4
GND
Ground. DC power is provided to the device on these pins.
5
SDA
Serial-Data Input/Output. SDA is the input/output pin for the 2-wire serial
interface. The SDA pin is open drain and requires an external pullup resistor.
6
SCL
2-Wire Serial-Clock Input. SCL is used to synchronize data movement on the
seria l interface and requires an external pullup resistor.
7
RST
Reset Output. It functions as a microprocessor reset signal. This pin is an open
drain output and requires an external pullup resistor.
8
V
CC
Power Supply. DC power is provided to the device on these pins.
Note: For more information about crystal selection and crystal layout considerations, refer to Application Note 58: Crystal Considerations with
Dallas Real -Time Clocks. The DS1672 can also be driven by an external 32.768kHz oscillator. In this configuration, the X1 pin is connected to
the external oscillator signal and the X2 pin is floated.
Figure 3. Recommended Layout for Crystal