SP207H Datasheet, PDF (6/14 Pages) Sipex Corporation – +5V High-Speed RS-232 Transceivers

+10V
a) C₂₊
GND
GND
b) C_2–
–10V
Figure 3. Charge Pump Waveforms
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_CC forces the input high, thus commit-
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.
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.
V_CC = +5V
+
C_{1 –}
–5V
+5V
+
C_{2 –}
–5V
C₄
+ – _{VDD Storage Capacitor}
– + _{VSS Storage Capacitor}
C₃
Figure 4. Charge Pump — Phase 3
TGoddard/SP207H/9614R0
SP207H/SP211H High–Speed Transceivers
6
© Copyright 2000 Sipex Corporation