Zywyn Corporation

ZT230E

Specifications subject to change without notice

Zywyn

9

August 2004

rev. 02

Typical Test Circuits

Measuring

Oscilliscope

TESTCIRCUIT

Maximum Data Rate Test Circuit

Notes:

A. R

L = 3kΩ , CL = 1000pF, TA = 25

oC,

One Driver Switching.

B. The pulse generator had the following characteristics:

PRR = 250 kbps, Zo = 50

Ω, 50% duty cycle,

T

r & Tf < 10ns

Figure 2. ZT230E TxIN to TxOut to RxOut (loopback to

Rx with 1000pF load) at 250kbps waveform

Figure 1. ZT230E TxIN to TxOut (no load) at 250kbps

waveform

Test Circuit RS232 Signal Characteristics

Figure 1 shows the normal RS232 transceiver function with

a TTL/CMOS signal applied to the input on channel 1 and the

resultant RS232 output shown on channel 2. This figure

shows a typical RS232 line driver output without loading. In

other words, this is the open circuit RS232 output voltage.

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 6.6V.

Figure 2 shows the RS232 transceiver function using the

TTL/CMOS input on channel 1 while showing the RS232

output on channel 2. This figure shows the RS232 signal

while the output is loaded with 3kohms and 1000pF. The

resistive load is the receiver's input impedance as the

driver's output is looped back to the receiver's input. The

resultant output on channel 3 is the receiver's TTL/CMOS

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

output level only drops 0.2V from its open circuit voltage

while running that 1Mbps. The RS-232 output on channel 2

also shows good signal integrity while at the high data rates,

which allows the receiver to process the signal will minimum

skew and delay. Zywyn's low-drop driver circuitry working

with its efficient voltage regulator allows superior line driving

capability with the bonus of ±15kV ESD immunity.