Programmable DTE/DCE,

+5V RS-232 Transceiver

_______________________________________________________________________________________

7

RS-232 Drivers

is ±8V when loaded with a nominal 5k

Ω RS-232

receiver. Under worst-case operating conditions

(including 116kbps data rate, 3k

Ω  2500pF load,

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 400k

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.

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,

V+

GND

MAX214

1µF

1µF

Rx

Tx

1µF

C1+

C1-

C2+

C2-

+5V

+5.5V

400k

5k

0V OR +5.5V

DRIVE

1µF

1µF

3k

+5.5V

CAPACITORS MAY BE

POLARIZED OR UNPOLARIZED

DTE/DCE

+5.5V

V-

+5.5V

+5.5V

SHDN

HI-Z

Figure 1. MAX214 Shutdown-Current Test Circuit

C1-

IL -

RL -

V+

S1

V -

S2

S5

S6

C1

C3

C2

IL +

RL +

S3

S4

S7

S8

C4

C1+

GND

GND

VCC

VCC

C2-

C2+

120kHz

Figure 2. Charge-Pump Diagram