ICL232IBE Datasheet, PDF (6/7 Pages) Intersil Corporation – +5V Powered, Dual RS-232 Transmitter/Receiver

ICL232
minimum of 300Ω with ±2V applied to the outputs and V_CC =
0V.
V+
V_CC
T_XIN
GND < T_XIN < V_CC
V-
400kΩ
300Ω
T_OUT
V- < V_TOUT < V+
FIGURE 7. TRANSMITTER
Receivers
The receiver inputs accept up to ±30V while presenting the
required 3kΩ to 7kΩ input impedance even it the power is off
(V_CC = 0V). The receivers have a typical input threshold of
1.3V which is within the ±3V limits, known as the transition
region, of the RS-232 specification. The receiver output is
0V to V_CC. The output will be low whenever the input is
greater than 2.4V and high whenever the input is floating or
driven between +0.8V and -30V. The receivers feature 0.5V
hysteresis to improve noise rejection.
V_CC
R_XIN
-30V < R_XIN < +30V _5kΩ
GND
R_OUT
GND < V_ROUT < V_CC
FIGURE 8. RECEIVER
T1_IN, T2_IN
OR
R1_IN, R2_IN
T1_OUT, T2_OUT
OR
R1_OUT, R2_OUT
t_PHL
t_PLH
V_OH
V_OL
Average Propagation Delay =
t_{PHL +} t_PLH
2
FIGURE 9. PROPAGATION DELAY DEFINITION
Applications
The ICL232 may be used for all RS-232 data terminal and
communication links. It is particularly useful in applications
where ±12V power supplies are not available for
conventional RS-232 interface circuits. The applications
presented represent typical interface configurations.
A simple duplex RS-232 port with CTS/RTS handshaking is
illustrated in Figure 10. Fixed output signals such as DTR
(data terminal ready) and DSRS (data signaling rate select)
is generated by driving them through a 5kΩ resistor
connected to V+.
+5V
1
C1 ⁺
1µF _- 3
4
C2 ⁺
1µF _- 5
16
ICL232
INPUTS
OUTPUTS
TTL/CMOS
TD
RTS
RD
CTS
11 ^T1
T2
10
12
9 ^{R2 R1}
- C3
+ ^1µF
2
5kΩ
CTR (20) DATA
TERMINAL READY
5kΩ _{DSRS (24) DATA}
SIGNALING RATE
6
- _C4
SELECT
+ 1µF ^RS-232
INPUTS AND OUTPUTS
14
TD (2) TRANSMIT DATA
7 _{RTS (4) REQUEST TO SEND}
13
RD (3) RECEIVE DATA
8 _{CTS (5) CLEAR TO SEND}
15
SIGNAL GROUND (7)
FIGURE 10. SIMPLE DUPLEX RS-232 PORT WITH CTS/RTS
HANDSHAKING
In applications requiring four RS-232 inputs and outputs
(Figure 11), note that each circuit requires two charge pump
capacitors (C1 and C2) but can share common reservoir
capacitors (C3 and C4). The benefit of sharing common
reservoir capacitors is the elimination of two capacitors and
the reduction of the charge pump source impedance which
effectively increases the output swing of the transmitters.
6
FN3020.7
July 28, 2005