SP505 Datasheet, PDF (33/35 Pages) Sipex Corporation – WAN Multi-Mode Serial Transceiver

LOOPBACK MODE...
The SP505 is equipped with two loopback
modes. Single-ended loopback internally
connects V.28 driver outputs to V.28 receiver
inputs. The signal path is non-inverting and
will support data rates up to 120kbps. The
propagation delay times are as specified
in the electrical specifications. To initiate
a single-ended loopback, the code "1010"
should be written to the driver decoder.
Differential loopback is implemented by
applying "1011" to the driver decoder. This
internally connects V.11 driver outputs to
V.11 receiver inputs. The signal path again
is non-inverting; the differential loopback
data rate can be at least 5Mbps.
Under loopback conditions the receiver
decoder is disabled. While the SP505 is in
either single-ended or differential loopback
mode, the driver outputs are tri-stated and
the receiver inputs are disabled.
RD(a) 70
RxD 1
RT(a) 37
RxC 20
CS(a) 66
CTS 80
DM(a) 68
DSR 78
RR(a) 35
DCD 19
IC(a) 39
RI 21
SCT(a) 76
SCT 79
SCTEN 7
MODE: Single-Ended Loopback
DRIVER/RECEIVER
DEC₃ DEC₂ DEC₁ DEC₀
1
0
1
0
RECEIVERS
DRIVERS
14 TxD
61 SD(a)
2 SDEN
13 DTR
58 TR(a)
3 TREN
16 RTS
54 RS(a)
4 RSEN
17 RL
47 RL(a)
18 RLEN
24 LL
51 LL(a)
5 LLEN
22 ST
42 ST(a)
23 STEN
15 TxC
63 TT(a)
6 TTEN
RD(a) 70
RxD 1
RD(b) 71
RT(a) 37
RxC 20
RT(b) 38
CS(a) 66
CTS 80
CS(b) 67
DM(a) 68
DSR 78
DM(b) 69
RR(a) 35
DCD 19
RR(b) 36
IC(a) 39
RI 21
IC(b) 40
SCT(a) 76
SCT 79
SCTEN 7
SCT(b) 77
MODE: Differential Loopback
DRIVER/RECEIVER
DEC₃ DEC₂ DEC₁ DEC₀
1
0
1
1
RECEIVERS
DRIVERS
14 TxD
61 SD(a)
59 SD(b)
2 SDEN
13 DTR
58 TR(a)
56 TR(b)
3 TREN
16 RTS
54 RS(a)
52 RS(b)
4 RSEN
17 RL
47 RL(a)
45 RL(b)
18 RLEN
24 LL
51 LL(a)
49 LL(b)
5 LLEN
22 ST
42 ST(a)
44 ST(b)
23 STEN
15 TxC
63 TT(a)
65 TT(b)
6 TTEN
Mode
Loopback
DEC = 1010
Driver Output
Receiver Input
non-inverting inverting non-inverting inverting
Driver Receiver
Input Output
tri-state tri-state >10KΩ to GND >10KΩ to GND active active
DEC = 1011
tri-state tri-state >10KΩ to GND >10KΩ to GND active active
Power down

V _CC=V_DD =V_SS=0V tri-s tate tri-sta te >1 0KΩ to GND >10KΩ to GND
Tri-state
DEC = 0000
tri-state tri-state >10KΩ to GND >10KΩ to GND
inactive
inactive
clamped
at ±0.6V
tri-state
Exar Coporation 48720 Kato Road, Fremont CA, 94538 • [phone] • Fax [phone] • www.exar.com
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SP505_100_081308