AMIS-49200 Datasheet, PDF (18/22 Pages) AMI SEMICONDUCTOR – Fieldbus MAU Chip

AMIS-49200 Fieldbus MAU
Data Sheet
Zero-Cross Detector
VDD
RXS
35
Level
Convert
VDD
RXA
34 Level
Convert
CCD
32
VCC
C1
ZC Tript Pt ^{Vtrip = Vmid}
Vhyst = + 40mV
Carrier Detector
VCC
VCC
C2
VHi50
CD_Output
VCC
C2
VLo50
RxSig
Vmid
R
(1Meg)
C
(60pF)
VHi50 = Vmid + 50mV
VLo50 = Vmid - 50mV
Filtered received signal
from Bandpass Filter
Figure 11: Receive Signal Detectors
5.0 AMIS-49200 as Replacement for Yokogawa µSAA22Q
The AMIS-49200 is a near pin-for-pin compatible replacement for the Yokogawa µSAA22Q Fieldbus MAU. There are some differences
between the two chips both in the internal operation, the required external connections and the value (or existence) of some of the
external components. These differences are small and those who used the µSAA22Q would most likely be able to use the AMIS-49200
in designs with only some component value changes.
5.1 Functional Differences Between the µSAA22Q and the AMIS-49200
5.1.1. Jabber Inhibit
The AMIS-49200 does not implement the Jabber Inhibit function in the µSAA22Q. Typically the AMIS-49200 will be connected with a
Link Controller chip such as the Yokogawa FIND1. This link controller has a Jabber Inhibit function so the absence of this function in the
AMIS-49200 should not be a problem.
As can be seen in Table 12, MDS_CTRL is only connected to ground if POL is connected to VDD. See Table 1 for a detailed
description of the interaction between MDS_CTRL and POL.
In Table 12, the µSAA22Q recommends that the JAB/ signal (pin 39) be connected to ground if the signal is not used. On AMIS-49200,
pin 39 must be connected to ground.
5.1.2. Low Power Mode
The low power mode on the µSAA22Q allows the user to have a quiescent current draw of less than 10mA yet still communicate at the
proper IEC 61158-2 signal levels. Very few, if any, Fieldbus devices are capable of operating at such a low current level so this
capability was not included in the AMIS-49200.
AMI Semiconductor – Jan. 07, M-20532-003
18
www.amis.com