+5V
10µF
1N5819
22µF
22µF
22µF
25
VCC
27 26 30 28
VDD C1+ C1- C2+
Charge Pump
31
C2-
VSS 32
22µF
A
B
RD(a) 70
14 TxD
RxD 1
RD(b) 71
RT(a) 37
RxC 20
RT(b) 38
CS(a) 66
61 SD(a)
59 SD(b)
13 DTR
58 TR(a)
56 TR(b)
16 RTS
CTS 80
CS(b) 67
DM(a) 68
DSR 78
54 RS(a)
52 RS(b)
17 RL
47 RL(a)
45 RL(b)
DM (b) 69
RR(a) 35
DCD 19
A — Receiver Tri-State Circuitry & V.35
terminaiton resistor circuitry for
RxD, RxC & SC. T
RR(b) 36
B — Driver Tri-State circuitry &V.35
termination circuitry for TxD,
TxC & S.T
IC(a) 39
RI 21
24 LL
51 LL(a)
49 LL(b)
22 ST
42 ST(a)
44 ST(b)
IC(b) 40
23 STEN
SCT(a) 76
15 TxC
SCT 79
63 TT(a)
RS-422 Mode
Input Word
0
1
0
0
0
1
0
0
SCTEN 7
SCT(b) 77
5
4
3
External
2
Latch
9
10
11
12
65 TT(b)
6 TTEN
SP504
(SEE PAGE 12 FOR GROUND PINS)
Note 1
For V.35 Termination, needs to be connected
for proper V.35 operation. A low on-
resistance (≤1Ω) FET or switch can be used
to connect and disconnect the resistor from
the non-inverting output.
Figure 19. SP504 Typical Operating Circuit
150Ω
Note 1
150Ω
Note 1
150Ω
Note 1
Exar Corporation 48720 Kato Road, Fremont CA, 94538 • 510-668-7017 • www.exar.com
20
SP504_102_121708