ISL1218 Datasheet, PDF (2/21 Pages) Intersil Corporation – Low Power RTC with Battery Backed SRAM

Block Diagram
ISL1218
SDA
SCL
SDA
BUFFER
SCL
BUFFER
I²C
INTERFACE
RTC
CONTROL
LOGIC
X1
X2
V_DD
V_TRIP
V_BAT
CRYSTAL
OSCILLATOR
RTC
DIVIDER
POR
FREQUENCY
OUT
SWITCH
INTERNAL
SUPPLY
ALARM
SECONDS
MINUTES
HOURS
DAY OF WEEK
DATE
MONTH
YEAR
CONTROL
REGISTERS
USER
SRAM
IRQ/
F_OUT
Pin Descriptions
PIN
NUMBER
SYMBOL
DESCRIPTION
1
X1
The X1 pin is the input of an inverting amplifier and is intended to be connected to one pin of an external 32.768kHz
quartz crystal. X1 can also be driven directly from a 32.768kHz source.
2
X2
The X2 pin is the output of an inverting amplifier and is intended to be connected to one pin of an external 32.768kHz
quartz crystal.
3
V_BAT This input provides a backup supply voltage to the device. V_BAT supplies power to the device in the event that the
V_DD supply fails. This pin should be tied to ground if not used.
4
GND Ground.
5
SDA
Serial Data (SDA) is a bidirectional pin used to transfer serial data into and out of the device. It has an open drain
output and may be wire OR’ed with other open drain or open collector outputs.
6
SCL
The Serial Clock (SCL) input is used to clock all serial data into and out of the device.
7
IRQ/F_OUT Interrupt Output/Frequency Output is a multi-functional pin that can be used as interrupt or frequency output pin. The
function is set via the configuration register.
8
V_DD
Power supply.
2
FN6313.0
June 22, 2006