Datasheet

TVP5158, TVP5157, TVP5156
www.ti.com SLES243G –JULY 2009–REVISED APRIL 2013
Table 4-25. AGC Gain Status
Subaddress 20h-21h
Default Read Only
Subaddress 7 6 5 4 3 2 1 0
20h Fine Gain [7:0]
21h Reserved Fine Gain [13:8]
These AGC gain status registers are updated automatically when the AGC is enabled; in manual gain control mode these register values
are not updated.
Because this register is a multi-byte register, it is necessary to "capture" the setting into the register to ensure that the value is not updated
between reading the lower and upper bytes. To cause this register to "capture" the current settings bit 0 of I
2
C register 24h (Status
Request) should be set to a 1. After the internal processor has updated this register, bit 0 of register 24h is cleared, indicating that both
bytes of the AGC gain status register have been updated and can be read. Either byte may be read first, because no further update occurs
until bit 0 of 24h is set to 1 again.
Table 4-26. Back-End AGC Status
Subaddress 23h
Default Read Only
7 6 5 4 3 2 1 0
Gain [7:0]
Current back-end AGC ratio = Gain/128.
Table 4-27. Status Request
Subaddress 24h
Default 00h
7 6 5 4 3 2 1 0
Reserved Capture
Capture
Setting a 1 in this register causes the inter processor to capture the current settings of the AGC status, noise measurement, and
the vertical line count registers. Because this capture is not immediate, it is necessary to check for completion of the capture by
reading the "capture" bit repeatedly after setting it and waiting for it to be cleared by the internal processor. After the "capture" bit is
0, the AGC status, noise measurement, and vertical line counters (20h/21h, 94h/95h, and A2h/A3h) have been updated, and can
be safely read in any order.
Table 4-28. AFE Gain Control
Subaddress 25h
Default F5h
7 6 5 4 3 2 1 0
Reserved ALC Reserved AGC
Reserved
For future compatibility, all reserved bits must be set to logic 1.
ALC
Active-high automatic level control (ALC) enable
0 ALC disabled (manual level control)
1 ALC enabled (default)
AGC
Active-high automatic gain control (AGC) enable
0 AGC disabled (manual gain control)
1 AGC enabled (default)
Copyright © 2009–2013, Texas Instruments Incorporated Internal Control Registers 55
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