TW2802 データシートの表示（PDF） - Unspecified

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TW2802

TW2802/4 Multiple Video Decoder For Security Applications

Unspecified 

TW2804/TW2802 Multiple Video Decoder

Preliminary

Functional Description

Video Input Formats

The TW280X supports all NTSC/PAL standard formats and has built-in automatic standard

detection circuit. The following Table 1 shows the identified standards. Automatic standard

detection can be overridden by writing the value into the IFMTMAN and IFORMAT register

(0x01, 0x41, 0x81, 0xC1). Even in no-video status, the device can be forced to free-run in a

particular video standard mode for fast locking by programming IFORMAT register.

Format

NTSC-M*

NTSC-J

NTSC-4.43*

Table 1 Input Video Format Supported

Line/Fv (Hz)

Fh (KHz)

525/59.94

15.734

525/59.94

15.734

NTSC-N

PAL-BDGHI

PAL-N*

PAL-M*

625/50

625/50

525/59.94

15.625

15.625

15.734

PAL-NC

625/50

15.625

PAL-60

525/59.94

15.734

Notes: * 7.5 IRE Setup

Fsc (MHz)

3.579545

4.43361875

3.579545

4.43361875

3.57561149

3.58205625

4.43361875

Analog-to-Digital Converter

The TW280X contains four 10-bit Analog to Digital converters that digitizes the analog video

inputs. As the inputs are digitized at greater than two times that of the Nyquist sampling rate,

only simple external anti-aliasing LPF are needed to prevent out-of-band frequencies. Each

ADC has two analog switches that are controlled by ANA_SW (0x22, 0x62, 0xA2, 0xE2)

registers. The A/D converters can also be put into power-down mode by the ADC_PWDN

(0x78) registers.

Techwell, Inc.

8

www.techwellinc.com

09/09/2003

Datasheet Rev. 2.4

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