~ National ~ Semiconductor - Al Kossow's Bitsavers

Electrical Characteristics Unless otherwise noted: VDD = 5.0V, Vss = -5.0V, DGND = AGND = OV,
T A = 25°C. All digital signals are referenced to DGND; all analog signals are referenced to AGND. (Continued)
Symbol
I
Parameter
I
Condition
I Min I Typ I Max I Units
SYSTEM PERFORMANCE
BER Bit Error Rate C2 LINE
Signal to Noise Ratio (SNR) required for ANSWER MODE
indicated Bit Error Rate (BER). Pline = BER = 10-3 4.7 dB
-30 dBm at RXIN, with added 5 kHz BER = 10-4 6.2
white noise (referred to 3 kHz), and BER = 10-5 7.5
- 11 dBm talker echo (reflected BER = 10-6 B.5
transmitter output power). All tests were CALLING MODE
;;, 5 x 106 bits at 1200 bps, and were BER = 10-3 6.3
performed on an AEA S3 test set. See BER = 10-4 7.2
Figure 2. BER = 10-5 B.6
BER = 10-6 9.2
CO LINE
ANSWER MODE
BER = 10-3 5.2 dB
BER = 10-4 6.9
BER = 10-5 B.4
BER = 10-6 10.2
CALLING MODE
BER = 10-3 7.0
BER = 10-4 B.6
BER = 10-5 10.3
BER = 10-6 11.B
fos Frequency offset: incoming carrier
frequency offset acquirable by receiver Zero errors in 105 bits, ±6 Hz
call/answer modes, flat,
CO, C2 lines.
Pline = -40 dBm
Note: Sit error Rate (SER) results will vary with test equipment setup, noise source, modem design, telephone interface, printed wiring board design and length of
SER test.
Noise source must have a crest factor of at least 4.7 and random distribution of 5 sigma or greater to obtain accurate results.
Pin Descriptions
Pin No. Label Description Pin No. Label Description
1 SLIM Connect external capacitor 6 SYNC Selects CHAR ASYNC or BIT
2 LIM between pins 1 and 2. (Note 1) SYNC mode. 1 = ASYNC mode:
enables XMIT & RCV buffers, sets
3 RXIN Line signal to modem; usually from
character length according to
2-wire/4-wire hybrid. AC coupling
MOD1, MOD2. 0 = SYNC mode:
is recommended. (Note 1)
disables buffers, selects TX clock
4 DOT Test pattern. In Data (TEST = 1) or source with MOD1, MOD2.
Analog Loop modes, substitutes a
7 EDET Energy Detect. In Data mode,
dotting pattern for TXD, and
EDET = 0 if valid signal above
overrides SYNC, MOD1 and
threshold is present for 155 ms
MOD2. If HS = 1 , provides a
± 50 ms, EDET = 1 if signal below
1200 bps dotting pattern (600 Hz
threshold for> 17 ms ±7 ms. In
square wave), and places RCVR
Dialer mode, follows on/off
and XMTR in SYNC mode with
variations of call-progress tones:
internal clock source. If HS=O,
EDET = 0 if tones present for
provides a 600 bps dotting pattern.
•
30 ms ± 5 ms, EDET = 1 if tones
1 = normal transmit data path,
absent for 36 ms ± 6 ms .
0= dotting.
B HS Selects data rate, and transmit!
5 ETC External Transmit Clock. 600 Hz or
(Note 2) receive clock rates. 1 selects
1200 Hz external clock providing
1200 bps, 0 selects 600 bps.
XMTR timing in SYNC mode,
selected by MOD1, MOD2. TXD
changes on negative edge,
sampled on positive edge.
Provided at SCT if selected.
5-19