Zywyn Corporation

ZT230E

Specifications subject to change without notice

Zywyn

6

August 2004

rev. 02

Table 2. EIA Standard Parameter Summary

RS232 Signal Characteristics

The charge pump voltage converter efficiently converts the

necessary voltage for the driver's output transistors so that

the RS232 output is close to the ideal rail voltage of 10V.

While loaded with a typical RS232 load, the driver's output

level only drops 0.2V from its open circuit voltage. Zywyn's

low-drop driver circuitry working with its efficient voltage

regulator allows superior line driving capability while meet-

ing the requirements of TIA/EIA-232-E.

The drivers are inverting transmitters, which accept TTL or

CMOS inputs and produces the RS-232 compliant signals

that is inverted relative to the input logic levels. Typically the

RS232 output voltage swing is ±6V. Even under the worst

case loading conditions of 3kohms and 2500pF, the output

is guaranteed to be ±5V, which adheres to the RS232

standard specifications. The transmitter outputs are pro-

tected against infinite short-circuits to ground without deg-

radation in reliability. The instantaneous slew rate of the

transmitter output is internally limited to a maximum of 30V/

µs in order to meet the TIA/EIA-232-E requirements.

The receivers convert RS-232 input signals to inverted TTL

signals. The inputs have a typical hysteresis margin of

500mV in order to account for signal degradation caused by

system interference and other noise related disturbers.

This ensures that the receiver is relatively immune to noisy

transmission lines. The input thresholds are 0.8V minimum

and 2.4V maximum, which are within the TIA/EIA-232

requirements. The receiver inputs are also protected against

voltages up to ±25V. Should an input be left unconnected,

a 5kohm pulldown resistor to ground will force the output of

the receiver to a high state.