SP332 Datasheet, PDF (7/10 Pages) Sipex Corporation – RS-232/RS-485 Multi-Mode Serial Transceiver

Phase 3
-Vdd charge storage- The third phase of the
clock is identical to the first phase- the trans-
ferred charge in C1 produces -5V in the negative
terminal of C1, which is applied to the negative
side of capacitor C2. Since C2+ is at +5V, the
voltage potential across C2 is 10V.
Phase 4
-Vdd transfer- The fourth phase of the clock
connects the negative terminal of C2 to ground
and transfers the generated 10V across C2 to C4,
the Vdd storage capacitor. Simultaneously with
this, the positive side of capacitor C1 is switched
to +5V and the negative side is connected to
ground, and the cycle begins again.
Since both V+ and V- are separately generated
from Vcc in a no load condition, V+ and V- will
be symmetrical. Older charge pump approaches
that generate V- from V+ will show a decrease
in the magnitude of V- compared to V+ due to
the inherent inefficiencies in the design.
The clock rate for the charge pump typically
operates at 15kHz. The external capacitors must
be 0.1µF with a 16V breakdown rating.
SP332 TYPICAL OPERATING CIRCUIT
RS-232 Mode
0.1µF
0.1µF
0V
0V
TTL/CMOS
TTL/CMOS
TTL/CMOS
TTL/CMOS
+5V
9 _C1+
5
VCC
12 _C1-
11
C2+
SP332
13
C2-
24 _{SEL A}
2 _{SEL B}
Vcc
400KΩ
26 TI1
T1
Vcc
400KΩ
27 TI2
T2
Vcc
400KΩ
28 TI3
T3
Vcc
400KΩ
1 TI4
T4
V+ ¹⁰
V- ¹⁴
0.1µF
LOOP ²³
BACK
TX1 6
TX2 7
TX3 4
TX4 3
0.1µF
TTL/CMOS
RS-232
RS-232
RS-232
RS-232
TTL/CMOS
TTL/CMOS
TTL/CMOS
TTL/CMOS
19 RX1
20 RX2
21 RX3
22 RX4
8
GND
RI1 15
R1
5KΩ
RI2 16
R2
5KΩ
RI3 17
R3
5KΩ
RI4 18
R4
5KΩ
25
SHUT
DOWN
RS-232
RS-232
RS-232
RS-232
TTL/CMOS
RS-485 Mode
0.1µF
0.1µF
+5V
+5V
TTL/CMOS
TTL/CMOS
TTL/CMOS
TTL/CMOS
TTL/CMOS
TTL/CMOS
TTL/CMOS
TTL/CMOS
+5V
9 _C1+
12 _C1-
11 _C2+
5
VCC
SP332
10
V+
14
V-
13 _C2-
24
2 ^{SEL A}
SEL B
Vcc
400KΩ
26 TI1
T1
27
TI2 _Vcc
400KΩ
28 TI3
T3
1
TI4
19 RX1
R1
20
RX2
0.1µF
23
LOOP
BACK
TX2 7
TX1 6
TX4 ³
TX3 4
RI2 16
15KΩ
RI1 15
15KΩ
21 RX3
R3
RI4 18
15KΩ
RI3 17
22 _RX4
8 _GND
15KΩ
25
SHUT
DOWN
0.1µF
TTL/CMOS
RS-485
RS-485
RS-485
RS-485
RS-485
RS-485
RS-485
RS-485
TTL/CMOS
TGoddard/SP332/9617R0
SP332 RS-232/RS-485 Multi-Mode Serial Transceiver
7
© Copyright 2000 Sipex Corporation