Datasheet

+5V, RS-232 Transceivers
with 0.1µF External Capacitors
8
MAX200–MAX209/MAX211/MAX213
Applications Information
Capacitor Selection
The type of capacitor used is not critical for proper
operation. Ceramic capacitors are suggested. To ensure
proper RS-232 signal levels over temperature when
using 0.1FF capacitors, make sure the capacitance
value does not degrade excessively as the temperature
varies. If in doubt, use capacitors with a larger nominal
value. Also observe the capacitors’ ESR value over tem-
perature, since it influences the amount of ripple on V+
and V-. To reduce the output impedance at V+ and V-,
use larger capacitors (up to 10FF). If polarized capaci-
tors are used, obey the polarities shown in Figure 1 and
the pin configurations.
Driving Multiple Receivers
Each transmitter is designed to drive a single receiver.
Transmitters can be paralleled to drive multiple receivers.
Driver Outputs When Exiting Shutdown
Figure 5 shows two driver outputs exiting shutdown. As
they become active, the two driver outputs go to oppo-
site RS-232 levels (one driver input is high, the other
is low). Each driver is loaded with 3kI in parallel with
2500pF. The driver outputs display no ringing or undesir-
able transients as they come out of shutdown.
Power-Supply Decoupling
In applications that are sensitive to power-supply noise,
decouple V
CC
to ground with a capacitor of the same
value as the charge-pump capacitors.
V+ and V- as Power Supplies
A small amount of power can be drawn from V+ and V-,
although this reduces noise margins.
Power Supplies for MAX201/MAX209
If at power-up the V+ supply rises after the V
CC
supply,
place a diode (e.g., 1N914) in series with the V+ supply.
Table 3. DB9 Cable Connections Commonly Used for EIA/TIA-232E and V.24
Asynchronous Interfaces
Table 2. Summary of EIA/TIA-232E, V.28 Specifications
PARAMETER CONDITION EIA/TIA-232E, V.28 SPECIFICATION
Driver Output Voltage: 0 Level
3kI to 7kI load
+5.0V to +15V
Driver Output Voltage: 1 Level
3kI to 7kI load
-5.0V to -15V
Output Level, Maximum No load
Q25V
Data Rate
3kI P R
L
P 7kI, C
L
P 2500pF
Up to 20kbps
Receiver Input Voltage: 0 Level — +3.0V to +15V
Receiver Input Voltage: 1 Level — -3.0V to -15V
Input Level, Maximum —
Q25V
Instantaneous Slew Rate, Maximum
3kI P R
L
P 7kI, C
L
P 2500pF 30V/Fs
Driver Output Short-Circuit Current, Maximum — 100mA
Transition Rate on Driver Output
V.28 1ms or 3% of the period
EIA/TIA-232E 4% of the period
Driver Output Resistance -2V < V
OUT
< +2V
300I
PIN NAME CONNECTION
1 Received Line Signal Detector, sometimes called Carrier Detect (DCD) Handshake from DCE
2 Receive Data (RD) Data from DCE
3 Transmit Data (TD) Data from DTE
4 Data Terminal Ready Handshake from DTE
5 Signal Ground Reference point for signals
6 Data Set Ready (DSR) Handshake from DCE
7 Request to Send (RTS) Handshake from DTE
8 Clear to Send (CTS) Handshake from DCE
9 Ring Indicator Handshake from DCE