Rainbow Electronics DS2404 - Manual (Page 23)

DS2404
23 of 29
Battery Operate Mode
Figure 17 shows the necessary connections for operating the DS2404 in Battery Operate mode.
BATTERY OPERATE MODE Figure 17
V
CC
Pin 1 & 16 Ground
V
BATB
Pin 9 Ground
V
BATO
Pin 10 2.8 to 5.5V
The V
BATO
pin is normally connected to any standard 3 V lithium cell or other energy source. The Battery
Operate mode also minimizes the power-consumption in applications where battery backup is not
required and the V
BATO
lead is directly connected to the system’s 5V supply.
NOTE:
In Battery Operate mode, the voltage on DQ must never exceed the voltage on V
BATO
if the 3-wire
interface is used. This restriction does not apply to the 1-Wire interface.
DEVICE OPERATION MODES
With its two ports and two power modes the DS2404 can be operated in several ways. While the
maximum voltage on the 1-Wire port (I/O) is always 6V, the maximum voltage on the 3-wire port (DQ)
depends on the power mode and actual operating voltage. A particular port is selected by setting the
control lines to a state that makes the other port inactive. See Table 1 for details.
When using the 3-wire port only and the DS2404 is wired for V
CC
Operate Mode (Battery Backed) the
1 Wire I/O pin can be used as counter input. This mode requires that the I/O lead is connected to V
CC
through a 5k W (typical) resistor. To enable communication through the 3-wire port a reset/presence
sequence has to be performed on the 1-Wire port after the system has powered up.