Programmable DTE/DCE,
+5V RS-232 Transceiver
RS-232 Drivers
I
SHDN
+5.5V
1µF
C1+
1µF
C1-
V
CC
V+
1µF
1µF
MAX214
MAX214
C2+ +5V
1µF
C2-
400k
Tx
V-
With V
CC
= 5V, the typical driver output voltage swing
is ±8V when loaded with a nominal 5kΩ RS-232
receiver. Under worst-case operating conditions
(including 116kbps data rate, 3kΩ
2500pF load,
V
CC
= 4.5V, maximum rated temperature) the output
swing is guaranteed to meet the ±5V minimum speci-
fied by EIA/TIA-232 and V.28. The open-circuit output
voltage swing ranges from (V+ - 0.6V) to V-.
Input thresholds are both CMOS and TTL compatible.
The inputs of unused drivers can be left unconnected
because 400kΩ pull-up resistors to V
CC
are included
on-chip. Since all drivers invert, the pull-up resistors
force the outputs of unused drivers low. The input
pull-up resistors typically source 10µA; in shutdown
mode, they are disconnected to reduce supply current.
When in low-power shutdown mode, the driver outputs
are turned off and their leakage current is less than
1µA, even if the transmitter output is back-driven with
voltages up to ±15V.
+5.5V
T
IN
Rx
T
OUT
3k
R
IN
5k
+5.5V
R
OUT
0V OR +5.5V
DRIVE
+5.5V
+5.5V
DTE/DCE
HI-Z
SHDN
GND
CAPACITORS MAY BE
POLARIZED OR UNPOLARIZED
RS-232 Receivers
The receivers convert the RS-232 signals to
CMOS-logic levels. They invert, to match the inversion
of RS-232 drivers. The guaranteed receiver input
thresholds are significantly tighter than the ±3V
thresholds required by the EIA/TIA-232E specification,
Figure 1. MAX214 Shutdown-Current Test Circuit
V+
S1
V CC
C1+
C1
S2
C3
S5
C2+ S6
C2
C4
S8
V-
C2-
GND
IL -
RL -
IL +
RL +
S3
GND
C1-
S4
V CC
S7
120kHz
Figure 2. Charge-Pump Diagram
_______________________________________________________________________________________
7
MAXIM [ MAXIM INTEGRATED PRODUCTS ]
