TB1305FG, TB1308FG
2007-07-11
13
Automatic sync processing mode (A-SYNC)
Counted horizontal and vertical frequency data to input signal are returned to READ BUS functions, H, V FREQ DET.
Also, the detected format is returned to H, V FORMAT and H, FM2 when the H/V frequencies are in internal defined
ranges. Input detection results, which indicate whether there is an input or not, for H, V-SYNC or HD, VD are returned to
H, V IN. In automatic sync processing mode (when A-SYNC = ON), the TB1305FG and TB1308FG operate as indicated
in the following table according to these READ data.
INPUT
CONDITION
H, V FORMAT status
H, V FM2 status
H, V IN status
HD, VD outputs
Standard format
The format as input
Known
Signal
The separated sync as
input
Non-standard
format
The status indicates not
the current condition
but the last detected
format.
Unknown
Signal
The separated sync as
input
No input
The status indicates not
the current condition
but the last detected
format.
Known:
The status indicates not
the current condition but
the last detected format.
No signal
Dummy HD and VD, of
which the frequency
depends on the H, V
FORMAT status
NOTE 3: The following format detection errors can occur when suppressed syncs are input.
525i input → 525p detected, 625i input→ 625p detected, 1125i input→ 1125p detected
525p/625p inputs → In case of the 525p/625p sync amplitude become bigger from zero to its standard
gradually, V-sync of the input is not detected even though the sync amplitude is got back to its standard
amplitude.
The V-sync separation performance to the suppressed sync input may be improved when VGA-SEP is set to
1 (VGA), though the H and V separation level are also changed.
NOTE 4: We recommend recognizing a format by H/V FREQ DET rather than one by H/V FORMAT because H
FORMAT and H FM2 can indicate an incorrect data for 525i, 625i, 525p, 1125/50i and 1125/60i caused by the
pseudo-syncs for copy guard or the equalizing pulses.
NOTE 5: Dummy HD and VD may become unstable while the mode is changing from one format to another.
By the way, in A-SYNC = OFF and S-MODE = ON mode, dummy HD and VD are output according to HV FREQ setting
when there is no input.
Manual sync processing mode (A-SYNC = OFF
*NOTE6)
HV FREQ = 625p is required to separate H-SYNC and V-SYNC properly. Set HV FREQ = 625p to count H/V-SYNC for
Manual sync processing mode.
The following is an example of how to detect H/V frequency when A-SYNC=OFF.
1. Set HV FREQ = 625p(0010) and read data such as H, V FREQ DET.
2. Detect the H/V frequencies by microprocessor or similar means, depending on the data obtained.
3. Set HV FREQ and so on to the detected mode.
4. Continue to monitor the obtained data such as H, V FREQ DET. When any alteration is recognized, set HV FREQ
= 625p(0010) and detect again.
Decision algorithms (for detection range, detection times and so on) for H/V frequency detection should be determined
taking into account the above-mentioned errors in measuring H/V frequencies and the other factors such as signal
conditions and I
2CBUS data transmission in the course of prototype TV set evaluation.
NOTE 6: We recommend recognizing formats for 525i and 625i signals by another device such as a color-decoder, not
by this product, because 525i and 625i signals include non-standard signals.
However, if you use this product to recognize formats including the standard 525i and 625i, set “A-SYNC =
ON”. Otherwise, H/V FREQ DET and H/V FORMAT may indicate incorrect value and VD-OUT may lock
irregularly for 525i and 625i signals. Refer to the “Application circuit 3 (system configuration)”, too.