AMIS-30585 Datasheet, PDF (9/17 Pages) AMI SEMICONDUCTOR – S-FSK PLC Modem

AMIS−30585
50/60 Hz Suppression Circuit
A typical attenuation for 50 Hz of this filter is 80 dB. A
mains coupling device has a typical attenuation of 60 dB.
This brings a mains frequency of 220 V rms well below the
sensitivity level. Typical values are shown in Table 6.
Oscillator
The oscillator works with a standard parallel resonance
crystal of 24 MHz. XIN is the input to the oscillator inverter
gain stage and XOUT is the output.
For correct functioning the following external circuit
must be connected to the oscillator pins (Values of capacitors
are indicative only and are given by the crystal
manufacturer. For a crystal requiring a parallel capacitance
of 20 pF CX must be around 30 pF.)
To guarantee startup the series loss resistance of the
crystal must be smaller than 80 W.
The parasitic leakage resistance between XIN and XOUT
must be higher than 1 MW. The parasitic leakage resistance
between XIN and VSS must be higher than 1 MW.
When working with a crystal, XOUT cannot be used
directly as a clock output because the voltage swing on this
pin is limited.
Zero Crossing Detector
The pin M50HZ_IN can be used as a mains zero crossing
detector input. If the mains are connected directly to this pin
a resistance must be connected in series to limit the current
through the protection diodes. Advisable is a series resistor
of 1 MW (R50). The zero crossing detector output is logic
zero when the input is lower than the falling threshold level
and a logic one when the input is higher than the rising
threshold level.
The falling edges of the output of the zero crossing
detector are filtered by a period between 0.5 ms and 1 ms.
Rising edges are not filtered.
5 V Safe Output
5 V safe pins are open drain output. The high level is
detained by placing a pull up resistance between the output
pin and the 5 V supply. Typical resistance value is 10 kW.
(TXD, TXEN3, TX_DTATA)
Table 6. TYPICAL EXTERNAL COMPONENT VALUES
C11
560
pF
C12
560
pF
R11
82 K
W
R12
39 K
W
C20
1
mF
Configuration
Configuration is loaded through the SCI interface from
the application controller.
• Mains frequency 50/60 Hz
• Master/slave/monitor/initialization configuration
• Baud rate selection 300/600/1200
Baud for 50 Hz mains
• Baud rate selection 360/720/1440
Baud for 60 Hz mains
• Carrier frequency programmation
• Carrier frequency spread
Configuration method and utilization are described in the
AMIS−30585 data book, user interface documentation.
Application Example
A typical application example is given below. The
example shows the AMIS−30585 with its companion
devices. Namely the power line driver (AMIS−3058), the
application controller and a meter device interface.
Between the modem chip and the line driver, an active
bandpass filter is used to reduce the noise outside the
transmission band. The filter is realized with external
passive components.
From the line driver, the connection to the mains is done
through a line transformer and a capacitive coupling.
From the application side, the interface between the
modem and the application is done through the SCI. The link
to the meter device will be done easily by using the meter
device interface chip. This device is used to realize the
physical interface between the controller and the standard
S0 pulse (DIN 19234) generator output of the meter device.
C1 = C2 = 325 pF, R1 = 22.6 K, R2 = 2.2 K, R3 = 16.5 K,
R4 = 1 K, R5 = 1.66 K.
Other values are given in the typical external components
paragraph.
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