Rainbow Electronics DS1342 - Manual (Page 5)

Low-Current I 2 C RTCs for High-ESR Crystals
DS1341/DS1342
5
Functional Diagram
Pin Description
DS1341/DS1342
P
N
N
N /4 /32 EXTSYNC
CONTROL LOGIC
OSC-1Hz
ALARM AND
CONTROL REGISTERS
CLOCK AND
CALENDAR REGISTERS
/2
128Hz OSC-1Hz
SQW/INTB
CLKIN/INTA
X1
X2
SCL
SDA
4.096kHz
8.192kHz
32.768kHz
MUX/
BUFFER
DIVIDER
EXT-1Hz
V CC
SERIAL BUS
INTERFACE AND
ADDRESS
REGISTER
PIN NAME FUNCTION
1 X1 Connections for a Standard 32.768kHz Quartz Crystal. The internal oscillator circuitry is
designed for operation with a crystal having a specified load capacitance (C
L ) of 6pF (DS1341)
or 12.5pF (DS1342). 2 X2
3 CLKIN/INTA
Clock Input/Active-Low Interrupt Output. This I/O pin is used to output an alarm interrupt or
accept an external clock input to drive the RTC counter. In the output mode, this is an open
drain and requires an external pullup resistor. If not used, connect this pin to ground.
4 GND Ground
5 SDA
Serial-Data Input/Output. SDA is the input/output pin for the I 2 C serial interface. The SDA pin is
open drain and requires an external pullup resistor.
6 SCL Serial-Clock Input. SCL is used to synchronize data movement on the serial interface.
7 SQW/INTB
Square-Wave/Active-Low Interrupt Output. This pin is used to output a programmable square
wave or an alarm interrupt signal. This is a CMOS push-pull output and does not require an
external pullup resistor. If not used, this pin can be left unconnected.
8 V CC DC Power Input. This pin should be decoupled using a 0.01FF or 0.1FF capacitor.