TGoddard/SP207H/9614R0

SP207H/SP211H High–Speed Transceivers

© Copyright 2000 Sipex Corporation

6

Figure 4. Charge Pump — Phase 3

age swing is

±9V with no load, and±5V minimum

with full load. The transmitter outputs are pro-

tected against infinite short–circuits to ground

without degradation in reliability. The SP207HB,

SP211H and SP211HB drivers can be tri–stated

by using the SHUTDOWN function.

In the “power off” state, the output impedance will

remain greater than 300 ohms, again satisfying the

RS-232 specifications. Should the input of the

driver be left open, an internal 400Kohm pullup

resistor to V

ting the output to a low state.

Because of the increased speed, the slew rate is

typically 60V/

µS which is above the RS-232

specifcation of 30V/

µS. This is the only param-

eter that exceeds the RS-232 limits.

Figure 3. Charge Pump Waveforms

+10V

a) C

2

+

GND

GND

b) C

2

–

–10V

–5V

+5V

–5V

+

+

++

–

–

–

–

Receivers

The receivers convert RS-232 input signals to

inverted TTL signals. Since the input is usually

from a transmission line where long cable lengths

and system interference can degrade the signal,

the inputs have a typical hysteresis margin of

500mV. This ensures that the receiver is virtu-

ally immune to noisy transmission lines. Should

an input be left unconnected, a 5Kohm pulldown

resistor to ground will commit the output of the

receiver to a high state.