Product Description Video IC AD724JRZ-R7 is a low cost RGB to NTSC/PAL encoder

Converts red, green, and blue color component signals to their

Corresponding luma (baseband amplitude) and chrominance-nance (subcarrier amplitude and phase) signal video integrated circuit AD724JRZ-R7

Use NTSC or PAL standards. These two outputs are also combined to provide a composite video output. All three outputs can simultaneously drive a 75° reverse-terminated cable. All Logitech cal inputs are TTL, 3v and 5v CMOS compatible. The chip operates from a single +5v power supply. No external delay lines or filters are required. When might the AD724 shut down

Not used. The video integrated circuit AD724JRZ-R7 accepts FSC or 4FSC clock. when a clock

Not available, a low cost parallel resonant crystal (3.58 MHz)

(NTSC) or 4.43 MHz (PAL)) and oscilla-on-chip AD724

tor generates the necessary subcarrier clocks. The AD724 also receives a subcarrier clock from an external video source.

The interface to the graphics controller is simple: the on-chip logic "XNOR" accepts the available vertical (VSYNC) and horizontal-

tal sync (HSYNC) signals and creates a composite sync

CSYNC signal on chip. If available, the AD724 will also connect VSYNC to a standard CSYNC signal

Logic HI and apply CSYNC to the HSYNC pin. The AD724 contains decoding logic to identify valid horizontal sync

Correct pulse insertion. On delay matching chips for U and V chrominance filters

The sampled data delay line is on the Y signal path. To prevent aliasing, include a 5MHz pre-filter in front of the delay line

Add a 5mhz post filter after the delay line for rejection

harmonics in the output. These low-pass filters are optimized

Minimum pulse overshoot. Total luma latency, relative

to Chroma, which has been designed to be time-aligned for direct input to

TV baseband. AD724 saves space

SOIC for 0°C to +70°C commercial tem-

perature range

Theory of Operation of Video Integrated Circuit AD724JRZ-R7

The video integrated circuit AD724JRZ-R7 is designed with three allowable modes

Apply the clock via the fins. These are FSC (Frequency Sub-Carrier) mode using CMOS clock, FSC mode using

On-chip crystal oscillator, 4FSC mode and CMOS clock application. For NTSC or . FSC frequency is 3.579545 MHz

4.433618 MHz is PAL. To use FSC mode, the select pin is pulled low

CMOS FSC clock applied to fins, or placed between parallel resonant crystals and appropriate tuning capacitors

The on-chip oscillator uses fin pins and AGND. exist-

A chip phase-locked loop (PLL) is used in these modes gener-

ate an internal 4FSC clock, which is divided by the execution numbers

and the creation of quadrature subcarrier signals

Chroma modulation. In 4FSC mode, the select pin is pulled high, and the phase-locked loop is pulled high. Refer to the AD724 block diagram (Figure 14), RGB

Inputs (714 mV pp max each) with external DC clamping

coupling capacitor.

Shenzhen Tianzhuo Weiye Electronics Co., Ltd.

In the past 10 years, Shenzhen Tianzhuo Weiye Electronics Co., Ltd. has seized the historical opportunities brought by China's reform and opening up and the rapid development of the electronics industry, adhered to customer-centricity and high-quality products as the foundation, and provided customers with one-stop procurement services for components. Won the respect and trust of customers, from an entrepreneurial company based in Huaqiangbei, Shenzhen Special Economic Zone, China, it has grown steadily into an electronic component supplier with several well-known brand product lines and customers in many countries and regions around the world. The electronic IC and 3C distributed and wholesaled sell well in the consumer market and enjoy a high status among consumers. The company has established long-term and stable cooperative relations with many retailers and agents.