cx25870 Conexant Systems, Inc., cx25870 Datasheet - Page 70

• Manufacturer Part Number: cx25870
• Description: Video Encoder With Adaptive Flicker Filtering And Hdtv Output
• Manufacturer: Conexant Systems, Inc.

1.0 Functional Description
1.3 Device Description
1.3.31 FIELD Pin Output
Figure 1-21. FIELD Pin Output Timing Diagram (NTSC-M, J, 4.43)
1-54
Composite
Composite
FIELD Pin
FIELD Pin
Output
Output
Output
Output
523
261
524
262
525
Like its predecessor, the Bt868/869, the CX25870/871 includes a FIELD pin
output. This signal is output only and is accessed through pin #37. The frequency
of the FIELD pin is 30 Hz during an NTSC video output, and 25 Hz throughout a
PAL or SECAM video output. The only programming step required to obtain the
FIELD output is to serially write the EN_OUT bit to 1.
tracks the analog interlaced field presently being transmitted by the CX25870/871
DACs. The peak-to-peak amplitude of this output will be from 0 V to the level
present on the VDD_CO and VDDL pins. If these pins are tied to 3.3 V , then the
FIELD high state is transmitted at a 3.3 V level. If these pins are tied to 1.8 V or
lower voltage, then the FIELD high state is transmitted at a 1.8 V or lower level.
The logical 0 level from FIELD will always be GND/VSS regardless of the
logical 1 voltage.
following the leading edge of the digital HSYNC* input or output.
shows the relationship between the FIELD and Composite (CVBS) outputs and
VSYNC* input for NTSC.
263
The purpose of this signal is to provide a digital TTL compatible output which
The FIELD output transitions after the rising edge of CLKI, two clock cycles
1
Analog
FIELD 1 = ODD
Analog
FIELD 2 = EVEN
264
2
265
3
VSYNC*
Start
266
Conexant
of
RESET*
4
267
Figure 1-22
Flicker-Free Video Encoder with Ultrascale Technology
5
268
6
269
illustrates this same relationship for PAL.
7
270
8
271
9
272
10
*FIELDI Bit = 0
CX25870/871
Figure 1-21
22
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