![](http://datasheet.mmic.net.cn/290000/SP505_datasheet_16150878/SP505_33.png)
33
Rev: A Date: 1/27/04
SP505 Multi–Mode Serial Transceiver
Copyright 2004 Sipex Corporation
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 propaga-
tion 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.
Mode
Driver Output
non-inverting inverting non-inverting
Receiver Input
Driver Receiver
inverting
Input Output
Loopback
DEC=1010
tri-state tri-state >10K to GND >10K to GND active
active
tri-state tri-state >10K to GND >10K to GND active
active
Power down
V
CC
=V
DD
=V
SS
=0V
clamped
at ±0.6V
tri-state tri-state >10K to GND >10K to GND inactive
Tri-state
DEC=0000
tri-state tri-state >10K to GND >10K to GND inactive tri-state
DEC=1011
MODE:
Differential Loopback
DRIVER/RECEIVER
DEC
3
DEC
2
DEC
1
DEC
0
1 0 1 1
RD(a) 70
RxD 1
RT(a) 37
RxC 20
SCT(a) 76
SCT 79
SCTEN 7
15 TxC
63 TT(a)
65 TT(b)
6 TTEN
RECEIVERS DRIVERS
22 ST
42 ST(a)
44 ST(b)
23 STEN
CS(a) 66
CTS 80
RR(a) 35
DCD 19
RR(b) 36
CS(b) 67
RT(b) 38
RD(b) 71
24 LL
51 LL(a)
49 LL(b)
5 LLEN
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
IC(a) 39
RI 21
IC(b) 40
DM(a) 68
DSR 78
DM(b) 69
IC(a) 39
RI 21
SCTEN 7
RECEIVERS DRIVERS
1 0 1 0
24 LL
51 LL(a)
5 LLEN
13 DTR
58 TR(a)
3 TREN
DM(a) 68
DSR 78
16 RTS
54 RS(a)
4 RSEN
17 RL
47 RL(a)
18 RLEN
RR(a) 35
DCD 19
CS(a) 66
CTS 80
RD(a) 70
RxD 1
RT(a) 37
RxC 20
SCT(a) 76
SCT 79
14 TxD
61 SD(a)
2 SDEN
15 TxC
63 TT(a)
6 TTEN
22 ST
42 ST(a)
23 STEN
MODE:
Single-Ended Loopback
DRIVER/RECEIVER
DEC
3
DEC
2
DEC
1
DEC
0