SP333 Datasheet, PDF (6/13 Pages) Sipex Corporation – +5V Only RS-232/AppleTalk Programmable Transceiver

+3V
RXEN
0V
5V
RX_x
V_IL
V_IH
RX_x
0V
1.5V _{f = 1MHz; tR < 10ns; tF < 10ns}
t_ZL
1.5V _{Output normally LOW}
1.5V
t_LZ
0.5V
1.5V ^{Output normally HIGH}
t_ZH
0.5V
t_HZ
Figure 6. Receiver Enable and Disable Times
THEORY OF OPERATION...
The SP333 is a single chip device that can be
configured via software for either RS-232 or
AppleTalk™ interface modes at any time. The
SP333 is made up of three basic circuit ele-
ments: single-ended drivers and receivers, dif-
ferential drivers and receivers, and charge pump.
APPLETALK™ DRIVERS/RECEIVERS...
To program the SP333 for MacMode, Pin 25
should be connected to a logic HIGH. In
MacMode, the SP333 offers a complete
AppleTalk serial interface.
The driver section of the AppleTalk interface is
made up of a differential driver and a single-
ended inverting driver. The differential driver
has voltage swings that are typically ±5V on
each output pin under loaded conditions, and
typically ±8V under no-load conditions. The
differential driver can maintain ±3.6V (mini-
mum) swings (per pin) under worst case load
conditions of 450Ω between the differential
output.
The differential driver is equipped with a tri-
state control pin. When TXEN is a logic LOW,
the differential driver is active. When the TXEN
pin is a logic HIGH, the differential driver
outputs are tri-stated. The TXEN pin only
functions in MacMode. The differential
AppleTalk driver can support data rates up to
10Mbps.
The single-ended AppleTalk driver also has
typical voltage output swings of ±5V under
loaded conditions, and ±8V under no-load con-
ditions. The single-ended AppleTalk driver can
maintain ±3.6V (minimum) swings under worst
case conditions of 450Ω to ground. The single-
ended AppleTalk driver can support data rates
over 400kbps.
The receiver section of the SP333 is made up of
a differential receiver, a single-ended non-in-
verting receiver , and a single-ended inverting
receiver. The differential receiver has an input
sensitivity of ±200mV over a common mode
range of ±7V. The receivers have a typical input
resistance of 15kΩ (12kΩ minimum). The
differential receiver can receive data up to
10Mbps.
The single-ended non-inverting receiver has a
±200mV input threshold, however, the input
voltage can vary between ±7V. The typical
input resistance of the single-ended non-invert-
ing receiver is 15kΩ (12kΩ minimum). The
single-ended non-inverting receiver can also
receive data up to 10Mbps.
The SP333 also has a single-ended inverting
receiver input. This receiver is basically an RS-
232 receiver (R5 receiver) and is typically used
as a GPI (General Purpose Input) in the
AppleTalk interface. The GPI input has TTL-
compatible input thresholds that can receive
TGoddard/SP333/9617R0
SP333 RS-232/AppleTalk Programmable Transceiver
6
© Copyright 2000 Sipex Corporation