ISL12020M Datasheet, PDF (4/32 Pages) Intersil Corporation – Low Power RTC with Battery Backed SRAM, Integrated ±5ppm Temperature Compensation and Auto Daylight Saving

Pin Configuration
ISL12020M
ISL12020M
(20 LD DFN)
TOP VIEW
X2 1
X2 2
X2 3
X2 4
X2 5
NC 6
V_BAT 7
GND 8
NC 9
NC 10
20 X1
19 X1
18 X1
17 X1
16 X1
15 NC
14 V_DD
13 IRQ/FOUT
12 SCL
11 SDA
Pin Descriptions
PIN
NUMBER
1, 2, 3, 4, 5
16, 17, 18,
19, 20
6, 9, 10, 15
7
11
12
13
14
8
SYMBOL
X2
X1
NC
V_BAT
SDA
SCL
IRQ/F_OUT
V_DD
GND
DESCRIPTION
Crystal Connection. The X1 and X2 pins are the input and output, respectively, of an inverting
amplifier and are also connected to the internal 32.768kHz quartz crystal, which is the timebase for
the real time clock. Compensation circuitry with an internal temperature sensor provides frequency
correction to ±5ppm over the operating temperature range from -40°C to +85°C. The X1 and X2 pins
are not to be connected to any other circuitry or power voltages, and are best left floating. Do not
connect in an application circuit, floating electrical connection.
No connection. Do not connect to a signal or supply voltage.
Backup Supply. This input provides a backup supply voltage to the device. VBAT supplies power to
the device in the event that the VDD supply fails. This pin can be connected to a battery, a Super
Capacitor or tied to ground if not used. See the Battery Monitor parameter in the “Electrical
Specifications” table “DC Operating Characteristics - RTC” on page 5.
Serial Data. SDA is a bi-directional pin used to transfer data into and out of the device. It has an
open drain output and may be ORed with other open drain or open collector outputs. The input buffer
is always active (not gated) in normal mode.
An open drain output requires the use of a pull-up resistor. The output circuitry controls the fall time
of the output signal with the use of a slope controlled pull-down. The circuit is designed for 400kHz
I²C interface speeds. It is disabled when the backup power supply on the VBAT pin is activated. SDA
is a bi-directional 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.
Serial Clock. The SCL input is used to clock all serial data into and out of the device. The input buffer
on this pin is always active (not gated). It is disabled when the backup power supply on the VBAT pin
is activated to minimize power consumption.
Interrupt Output/Frequency Output (Default 32.768kHz frequency output). This dual function pin
can be used as an interrupt or frequency output pin. The IRQ/F_OUT mode is selected via the frequency
out control bits of the control/status register. Multi-functional pin that can be used as interrupt or
frequency output pin. The function is set via the configuration register. The output is open drain and
requires a pull-up resistor.
Interrupt Mode. The pin provides an interrupt signal output. This signal notifies a host processor
that an alarm has occurred and requests action. It is an open drain active low output.
Frequency Output Mode. The pin outputs a clock signal, which is related to the crystal frequency.
The frequency output is user selectable and enabled via the I²C bus. It is an open drain output.
Power supply. Chip power supply and ground pins. The device will operate with a power supply from
VDD = 2.7V to 5.5VDC. A 0.1µF capacitor is recommended on the V_DD pin to ground.
4
FN6667.4
February 11, 2010