Rainbow Electronics DS1615 - Manual (Page 3)

DS1615
3 of 24
DS1615 BLOCK DIAGRAM Figure 1
SIGNAL DESCRIPTIONS
The following paragraphs describe the function of each pin.
V
CC
- V
CC
is a +5-volts input supply. Communication with the DS1615 can take place only when V
CC
is
connected to a +5-volts supply.
V
bat
- Battery input for standard lithium cell or other energy source. All functions of the DS1615 with the
exception of the serial interface circuitry are powered by V
bat
when V
CC
< V
bat
. All functions are powered
by V
CC
when V
CC
> V
bat
. If a battery or other energy source is not used the V
bat
pin should be connected
directly to GND.
GND - Ground
COMSEL (Communication Select Input) - This pin determines whether serial communication is
asynchronous or synchronous. When pulled high to V
CC
, communication is synchronous and will take
place via the SCLK, I/O, and RST pins. When COMSEL is tied to ground, asynchronous communication
utilizing the TX and RX pins is selected. If this pin is floated, the DS1615 will operate in the
asynchronous communications mode since the COMSEL pin has a weak internal pulldown resistor.
Tx (Transmit Output) - Transmit output of the asynchronous serial interface. Tx is tri-stated whenever
V
CC
< V
bat
.
Rx (Receive Input) - Receive input of the asynchronous serial interface.
SCLK (3-wire Serial Clock Input) - The SCLK pin is the serial clock input for the 3-wire synchronous
communications channel.