AS5501 / AS5502 Multimode Powerline Modem
Data Sheet
The received signal gets filtered by the BANDPASS filter. An AGC-function is implemented
in this filter, to have improved performance over a wide range of input signal amplitude. The
filtered signal gets transferred to a low frequency band by the use of an MIXER-CIRCUIT so
that the frequency-band can be further reduced by an additional IF_BANDPASS. The
IF-filter output-signal gets DEMODULATED, FILTERED and SYNCHRONIZED to a
receive-clock. In receive mode the CLOCK-RECOVERY circuit is generating the
receive-clock locked to the RX-data edges. The input signal gets compared with a fixed
CARRIER DETECT threshold to get valid RX-data to be further processed by the connected
CPU only.
1.3.1 RXBPF
The bandpass-filter eliminates the frequency components which are not of interest. The
Bandwidth is programmable in 3 steps with the control-bits RXBW1 and RXBW2.
RXBW1 RXBW2 BW/Fcenter BW @ 72.00kHz BW @ 82.05kHz BW @ 132.45kHz
0
1
0
0
0
1
+/-4.2%
+/-1.8%
+/-2.3%
(6.8kHz)
3.0kHz
(11.0kHz)
4.8kHz
6.0kHz
(2.6kHz)
(3.3kHz)
(3.7kHz)
(6.0kHz)
The center-frequency of the filter is defined by the SC-Clock-Frequency (MRK-REG and the
bits BD1,2) in steps of 150Hz. (See paragraph 1.2.1 FREG_GEN).
Frequency-Response with RXBW1=1, RXBW2=0:
Fin / Fcenter
0.67
typ. rel. Gain
-45dB
0.98
-3dB
0.99
0.0dB
1
reference
0.0db
1.01
1.02
-3dB
1.5
-45dB
As already mentioned in the transmitter description, the AAF and SMF of the bandpass-filter
are tuned according to the SC-Clock and therefore to the BPF-centerfrequency.
An additional attenuation of the mains-frequency (50Hz ..) is not needed because of the
external coupling which is already a very good filter for that.
The input-voltage range which has to be handled is 1.5mV ... 1.5Vrms. The signal of the
input-pin RXIN gets buffered and lowpass-filtered by the RXBUF with a fixed gain of 0.66.
(Max. input level 14Vpp@transformer =>2.2Vpp@Rxin =>1.5Vpp@FilterInput)
The gain of the SC-BPF is controlled by the AGC loop to keep the filter-output RXO
constant at 1.0Vp for a wide range of input-dynamic. In total there is a variable gain from -3.6
to +41.4dB in steps of 1dB.
V(Line)
min -56.5dBV = 1.5mVrms 3.75mVrms = 10.6mVpp
max +6dBV = 2.0Vrms 5.0Vrms = 14.0Vpp
V(Vout)
V(RxIn)
1.7mVpp
2.2Vpp
V(RXO)
0.20Vpp
1.45Vpp
The window-comparator threshold for the AGC-control is set to 1.02V+/-12%. The
AGC-UDC will be clocked by 8*Fbaud which gives a max. settling time of 9.4ms at 600bps.
Rev A, May 2000
Page 14/25
AMSCO [ AMS(艾迈斯) ]
