LMH1983 Datasheet, PDF (20/55 Pages) National Semiconductor (TI) – Generating 44.1 kHz Based highly integrated programmable audio

LMH1983
SNLS309I – APRIL 2010 – REVISED DECEMBER 2014
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10ns / div
Top 200mV / div
Bottom 1V / div
Figure 15. TOF1 Timing
Top Trace CLKout1, Bottom Trace TOF1
4 ns / div
Top 200 mV / div
Bottom 1V / div
Figure 16. TOF2 Timing
Top Trace CLKout2, Bottom Trace TOF2
4ns / div
Top 200mV / div
Bottom 1V / div
Figure 17. TOF3 Timing
Top Trace CLKout3, Bottom Trace TOF3
10 ns / div
Top 200 mV / div
Bottom 1V / div
Figure 18. TOF4 Timing
Top Trace CLKout4, Bottom Trace TOF4
8.4 Device Functional Modes
8.4.1 Reference Detection
The device uses Auto Format Detect as the default mode, as the device determines the reference format among
those shown in Auto Format Detection Codes, and initiates the internal configurations accordingly. There are 31
pre-defined formats plus one format that the user can define. The device recognizes a format by measuring the
H_IN input frequency and looking at the V_IN and F_IN inputs. The device then determines if the reference input
format is an interlaced or progressive input. For some formats such as a 10 MHz or 27 MHz Hsync reference, if
H_IN and V_IN create a spurious input, the device will not properly recognize the reference input and will not lock
properly to the reference. Because of this, if H_IN has one of these 'special' signals on it, V_IN and F_IN should be
muted.
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