SP505 Datasheet, PDF (18/35 Pages) Sipex Corporation – WAN Multi-Mode Serial Transceiver

FEATURES…
The SP505 is a highly integrated serial trans-
ceiver that allows software control of its inter-
face modes. Similar to the SP504, the SP505
offers the same hardware interface modes for
RS-232 (V.28), RS-422A (V.11), RS-449, RS-
485, V.35, EIA-530 and includes V.36 and EIA-
530A. The interface mode selection is done via
a 4–bit switch for the drivers and receivers. The
SP505 is fabricated using low–power BiCMOS
process technology, and incorporates a Sipex–
patented (5,306,954) charge pump allowing +5V
only operation. Each device is packaged in an
80–pin JEDEC Quad FlatPack package.
The SP505 is ideally suited for wide area net-
work connectivity based on the interface modes
offered and the driver and receiver configura-
tions. The SP505 has seven (7) independent
drivers and seven (7) independent receivers. In
V.35 mode, the SP505 includes the necessary
components and termination resistors internal
within the device for compliant V.35 operation.
THEORY OF OPERATION
The SP505 is made up of five separate circuit
blocks — the charge pump, drivers, receivers,
decoder and switching array. Each of these
circuit blocks is described in more detail below.
Charge–Pump
The SP505 charge pump is based on the SP504
design where Sipex's patented charge pump
design (5,306,954) uses a four–phase voltage
shifting technique to attain symmetrical 10V
power supplies. The charge pump still requires
external capacitors to store the charge. In addi-
tion the SP504 charge pump supplies +10V or
+5V on V_SS and V_DD depending on the mode of
operation. There is a free–running oscillator
that controls the four phases of the voltage
shifting. A description of each phase follows.
The SP505 charge pump is used for RS-232
where the output voltage swing is typically
+10V and also used for RS-423. However, RS-
423 requires the voltage swing on the driver
output be between +4V to +6V during an open-
circuit (no load). The charge pump would need
to be regulated down from +10V to +5V.
A typical +10V charge pump would require
external clamping such as 5V zener diodes on
V_DD and V_SS to ground. The +5V output has
symmetrical levels as in the +10V output. The
+5V is used in the following modes where RS-
423 (V.10) are used: RS-449, EIA-530, EIA-
530A and V.36.
Phase 1 (±10V)
— V_SS charge storage — During this phase of
the clock cycle, the positive side of capacitors
Ctthra_{1ennasnsfwedrirCtec2dhaetrdoetoCing2}i_{–rt.ioauSllniyndccaehnadCrtg2h+}eedicshtocaor+gn5enVoecn. _{tCCedl1+–}
is
is
to
+5V, the voltage potential across capacitor C₂ is
now 10V.
Phase 1 (±5V)
— V_SS & V_DD charge storage and transfer —
gcWctoharopia+turah5gcnVetidht,ooearCnn.C^ldS^{+C1i5i1ams–}VntuidhslcetChtanr^{2naarsecngwoasepufietasocrlcnrhyieettCdohdr}₂^{etst+ooCiint2}sgh^{–irtteioirsaauVslnnlwSysdS}ficetaschrtnhroaederrdgdatghettoodee
the V_DD storage capacitor.
V_CC = +5V
+
C_{1 –}
–5V
+5V
+
C_{2 –}
–5V
C₄
+ – V_DD Storage Capacitor
– + _{VSS Storage Capacitor}
C₃
Figure 45. Charge Pump Phase 1 for +10V.
V_CC = +5V
+
C_{1 –}
–5V
+5V
+
C_{2 –}
C₄
+ – _{VDD Storage Capacitor}
– + _{VSS Storage Capacitor}
C₃
Figure 46. Charge Pump Phase 1 for +5V.
Rev: A Date: 1/27/04
SP505 Multi–Mode Serial Transceiver
18
© Copyright 2004 Sipex Corporation