CDB61581 Datasheet, PDF (5/16 Pages) Cirrus Logic – Universal Line Interface Unit

CDB61581
6. LED INDICATORS
The four-LED pack D1 indicates signal states on
LATN1, LATN2, LOS and NLOOP. The LOS
LED indicator illuminates when the line interface
receiver has detected a loss of signal. The NLOOP
LED indicates if Network Loopback is in opera-
tion. The LATN1/LATN2 LED’s indicate the at-
tenuation level of the received signal; reading how
much the incoming signal is below the nominal ex-
pected signal level. See Table 1 for details.
7. BUFFERING
Buffer U2 provides additional drive capability for
the SW1 and Host mode connections. The buffer
outputs are filtered with an (optional) RC network
(not initially populated) to reduce the transients
caused by buffer switching.
8. TRANSFORMER SELECTION
The evaluation board is supplied from the factory
with PE-64936 (1:1), PE-65351 (1:2) and T-1054
(1:1.5) transformers by Pulse Engineering. The
socket T1 on the board is for receive side trans-
former and T2 is for the transmit side. In the
matched impedance mode HDR1-HDR2 should be
placed in the MATZ positions, and in the low im-
pedance mode in the LOWZ positions. Please see
Table 2 for details on transformers selection.
9. PROTOTYPING AREA
An ample prototyping area with power supply and
ground connections is provided on the evaluation
board. This area can be used to develop and test a
variety of additional circuits such as framer devic-
es, system synchronizer PLLs, or specialized inter-
face logic.
LATN1
ON
OFF
ON
OFF
LATN2
ON
OFF
OFF
ON
Attenuation Level (dB)
0
7.5
15
22.5
Table 1. LATN Settings
Mode
T1 (100 Ω)/LH/Low Z*
E1 (120 Ω)/LH/Low Z
T1 (100 Ω)/SH/Mat Z
E1 (75 Ω)/SH/Mat Z
E1 (120 Ω)/SH/Mat Z
TX Transformer
1:2
1:2
1:1.5
1:1.5
1:1.5
RX Transformer
1:1
1:1
1:1
1:1
1:1
R1-R2
50 Ω
60 Ω
50 Ω
37.5 Ω
60 Ω
R3-R4
12.5 Ω
15 Ω
0**
0**
0**
Table 2. Transformer and Resistor Options
SH=Short Haul; LH = Long Haul; Mat Z = Matched Impedance; Low Z = Low Impedance
* Default setting from the factory; **R3-R4 are shorted by placing HDR1-HDR2 in MATZ positions.
DS211DB2
5