tza3054a NXP Semiconductors, tza3054a Datasheet - Page 7

• Manufacturer Part Number: tza3054a
• Description: 100 Mbits/s To 3.2 Gbits/s A-rate Tm Limiting Amplifier
• Manufacturer: NXP Semiconductors

Philips Semiconductors
9397 750 13466
Objective data sheet
8.3 Loss of signal indicator
Besides the analog LLD output, a digital LOS indication circuit is also incorporated in the
TZA3054A. The LLD level is internally compared with a loss of signal threshold, which can
be set via an external resistor connected to pin LOSTH (this is the default mode after
power-up) or by means of an internal Digital-to-Analog Converter (DAC). If the DAC is
used, programmed with I
value of the required threshold needs to be programmed into the I
(11h). The default value is 00h, so no LOS can be generated.
If the received signal strength is below the threshold value the LOS open-drain output will
be pulled LOW. The LOS open-drain output requires an external pull-up resistor in the
range of 4.7 k to 10 k . A default hysteresis of 3 dB is applied in the comparator.
I
of 0 dB to 7 dB in steps of 1 dB, a CMOS style LOS output instead of the default
open-drain configuration and programmable LOS polarity. These features provide
“any-interface” in the application; see
2
Fig 5. LLD voltage as a function of the RF input voltage.
C-bus register LOSCNF (10h) provides more flexibility, e.g. a programmable hysteresis
V
(mV)
LLD
1220
880
540
200
Rev. 01 — 12 August 2004
2
C-bus bit I2CLOSTH in I
1
100 Mbit/s to 3.2 Gbit/s A-rate
Figure
10
6.
S
LLD
2
C-bus register LOSCNF (10h), the
100
V
© Koninklijke Philips Electronics N.V. 2004. All rights reserved.
IN(p-p)
(mV)
001aab367
2
C-bus register LOSTH
1000
TZA3054A
limiting amplifier
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