Rainbow Electronics DS1374 - Manual (Page 8)

DS1374
I 2 C, 32-Bit Binary Counter Watchdog RTC with
Trickle Charger and Reset Input/Output
8 _____________________________________________________________________
Pin Description
PIN
µSOP SO
NAME FUNCTION
1, 2 — X1, X2
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. Pin X1 is the input to the
oscillator and can optionally be connected to an external 32.768kHz oscillator. The output of the
internal oscillator, pin X2, is floated if an external oscillator is connected to pin X1.
3 13 V BACKUP
Connection for a Secondary Power Supply. Supply voltage must be held between 1.3V and 3.7V
(-18 and -3) or 1.3V and 5.5V (-33) for proper operation. This pin can be connected to a primary cell
such as a lithium button cell. Additionally, this pin can be connected to a rechargeable cell or a super
cap when used with the trickle-charge feature. UL recognized to ensure against reverse charging
when used with a lithium battery.
4 14 RST
Active-Low, Open-Drain Output with a Debounced Pushbutton Input. This pin can be activated by a
pushbutton reset request, a watchdog alarm condition, or a power-fail event. It has an internal 50k
Ω
pullup resistor.
5 15 GND Ground
6 16 SDA
Serial Data Input/Output. SDA is the input/output for the 2-wire serial interface. The SDA pin is open
drain and requires an external pullup resistor.
7 1 SCL
Serial Clock Input. SCL is the clock input for the 2-wire serial interface and is used to synchronize
data movement on the serial interface.
8 2 INT
Interupt. This pin is used to output the alarm interrupt or the watchdog reset signal. It is active-low
open drain and requires an external pullup resistor.
9 3 SQW
Square-Wave Output. This pin is used to output the programmable square-wave signal. It is open
drain and requires an external pullup resistor.
10 4 V CC DC Power for Primary Power Supply
— 5–12 N.C. No Connection. Must be connected to ground.
CLOCK
DIVIDER
32-BIT
COUNTER
MUX
4.096kHz
1Hz X1
X2
8.192kHz
32.768kHz
1Hz/0.96kHz
ALARM/
WATCHDOG
STAT/CTRL/
TRICKLE
24-BIT
COUNTER
INT
CONTROL
RST
CONTROL
2-WIRE
INTERFACE
POWER
CONTROL
AND
TRICKLE
CHARGE
V CC
V
BACKUP
GND
SDA
SCL
RST
SQW
INT
DS1374
Figure 4. Functional Diagram