DS2480 Dallas Semiconducotr, DS2480 Datasheet - Page 21

• Manufacturer Part Number: DS2480
• Description: Serial 1.Wire Line Driver
• Manufacturer: Dallas Semiconducotr

HARDWARE APPLICATION EXAMPLES
This section discusses five typical application scenarios
of the DS2480. When directly designed into a new prod-
uct, the device can be connected as shown in Figure
10a.
UART DIRECT Figure 10a
+/(–) 5V RS232 Figure 10b
The signals DTR and RTS provide the power to operate
the DS2480. The resistor in the TXD line and the
Schottky diode limit the negative voltage at the TXD pin
of the DS2480 to 0.3V maximum. The resistor is typi-
cally 4.7 k . If the inverting driver is current–limited to 1
mA the resistor is not required.
OR C
UART
OR C
UART
DRIVER/
LEVEL SHIFTER
START
START
GND
L
DTR
RTS
RXD
TXD
POWER
STEALING
L
SOUT (TXD)
SIN (RXD)
1
0
0
1
M
M
STOP
REGULATOR
STOP
VOLTAGE
The circuit becomes more complex if a 1–Wire bus is to
be interfaced to a port that provides and expects
inverted signals, but does not necessarily meet the
RS232C ( 12V) standard (Figure 10b).
From the DS2480’s perspective, this circuit will work
with inverted signals of 5V as well as 0 to 5V. Depend-
ing on the voltage levels the host expects, it may be nec-
essary to generate a negative voltage on the RXD line.
Figure 10c shows how this can be accomplished for a
true RS232C system.
12V
(5V)
SEE TEXT
5V
5V
12V
(5V)
V
RXD
TXD
PP
DS2480
V
RXD
TXD
PP
GND
V
DS2480
DD
GND
V
DD
1–W
POL
POL
1–W
1–WIRE BUS
RETURN
1–WIRE BUS
RETURN
042498 21/26
DS2480