AN402| Application Note
Maxim > App Notes > COMMUNICATIONS CIRCUITS Keywords: line build-out, LBO, pulse amplitude
TELECOM
Mar 21, 2003
APPLICATION NOTE 402
Additional Pulse Amplitude Settings for DS2148, DS21348, DS21Q48, DS21Q348 and DS21448
Abstract: This application note shows how to use undocumented settings to modify output amplitudes.
Introduction
This application note provides the register settings for the DS2148/DS21348/DS21Q48/DS213Q48 and DS21448 to configure the transmitter for pulse amplitudes that are different than the line build-out (LBO) modes documented in the respective data sheets. The following tables list the register settings and define the resulting pulse amplitudes for the 3.3V (DS21348, DS21Q348) and 5V (DS2148, DS21Q48) devices. Table 1. DS21348, DS21Q348 Register Settings Operating Voltage: 3.3V (VSM pin wired low) Applicable Devices: DS21348, DS21Q348 Applicable Device Revisions: A2, B1, C1, and C2 (DS21Q348) Operating Mode: E1 L2 L1 L0 APPLICATION (CCR4.7) (CCR4.6) (CCR4.5) 0 0 1 1 1 1 1 1 0 1 0 1 75!& normal 120!& normal 120!& normal with high return loss 120!& normal with high return loss
TYPICAL CHANGE IN PULSE AMPLITUDE 7% enhancement over LBO setting 0 8% enhancement over LBO setting 1 8% attenuation over LBO setting 5 4% attenuation over LBO setting 5
RETURN Rt (!&) LOSS (dB) N.M. N.M. 21 21 0 0 9.1 10
N.M. = not meaningful
Table 2. DS2148, DS21Q48 Register Settings Operating Voltage: 5V (VSM pin wired high) Applicable Devices: DS2148, DS21Q48 Applicable Device Revisions: A2, B1, C1 and C2 (DS21Q48) Operating Mode: E1 L2 L1 L0 APPLICATION (CCR4.7) (CCR4.6) (CCR4.5) 0 0 1 1 1 1 1 1 0 1 0 1 75!& normal 120!& normal 120!& normal with high return loss 120!& normal with high return loss
TYPICAL CHANGE IN PULSE AMPLITUDE 10% enhancement over LBO setting 0 10% enhancement over LBO setting 1
RETURN Rt (!&) LOSS (dB) N.M. N.M. 0 0 22 33
10% attenuation over LBO 21 setting 5 10% enhancement over LBO setting 5 21
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