LE58QL021BVC Zarlink, LE58QL021BVC Datasheet - Page 37

• Manufacturer Part Number: LE58QL021BVC
• Description: QUAD, SLAC, PROG CODEC, 3.3V, 20 I/0, PQT44, LEAD FREE
• Manufacturer: Zarlink

Default Filter Coefficients
The QLSLAC device contains an internal set of default coefficients for the programmable filters. The default filter gains are
calculated based on the application circuit shown on
gain of 500 (K1). The transmit relative level is set to +0.28 dBr, and the receive relative level is set to –4.39 dBr. The equalization
filters (X and R) are not optimized and the Z and B filters are set to zero. The nominal input impedance was set to 812 Ω. If the
SLIC device circuit differs significantly from this design, the default gains cannot be used and must be replaced by programmed
coefficients. The balance filter (B) must always be programmed to an appropriate value.
To obtain this above-system response, the default filter coefficients are set to produce these values:
GX gain = +6 dB, GR gain = –8.984 dB
AX gain = 0 dB, AR gain = 0 dB, input attenuator on (DGIN = 0)
R filter: H(z) = 1, X filter: H(z) = 1
Z filter: H(z) = 0
B filter: H(z) = 0
AISN = cutoff
Notice that these default coefficient values are retained in a read-only memory area within the QLSLAC device, and those values
cannot be read back using any data commands. When the device is selected to use default coefficients, it obtains those values
directly from the read-only memory area, where the coefficient read operations access the programmable random access data
memory only. If an attempt is made to read back any filter values without those values first being written with known programmed
data, the values read back are totally random and do not represent the default or any other values.
PCLK
PCLK
FS
FS
Figure 25. Robbed-Bit Frame
Normal Frame (Not Robbed-Bit)
Zarlink Semiconductor Inc.
Robbed-Bit Frame
page
61. This SLIC device has a transmit gain of 0.5 (GTX) and a current
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