**AD9887AKSZ-170: A Comprehensive Technical Overview and Application Guide**
The **AD9887AKSZ-170** from Analog Devices is a high-performance, triple 8-bit analog interface digitizer specifically designed for processing analog RGB graphics signals from personal computers and workstations. This integrated circuit (IC) is a cornerstone in applications requiring the precise and reliable conversion of high-resolution analog video to digital formats, making it an essential component in digital displays, projectors, and advanced video processing systems.
**Architecture and Core Technical Features**
At its heart, the AD9887AKSZ-170 is engineered to handle the demanding requirements of modern video systems. Its architecture integrates three high-speed, 8-bit analog-to-digital converters (ADCs), each operating at a maximum sampling rate of **170 MSPS (Mega Samples Per Second)**. This high sampling rate is critical for supporting high-resolution video formats, including UXGA (1600x1200) at 60 Hz and beyond.
Key technical characteristics include:
* **Triple 8-Bit, 170 MSPS ADCs:** The three independent channels simultaneously sample the Red, Green, and Blue analog signals, ensuring precise color representation and synchronization.
* **Integrated Phase-Locked Loop (PLL):** The on-chip PLL generates the high-speed sampling clock directly from the incoming horizontal sync (HSYNC) signal. This eliminates the need for an external clock source and ensures the sampling clock is **phase-locked to the pixel clock** of the incoming analog signal, which is vital for stable and jitter-free image capture.
* **Programmable Gain, Offset, and Clamp Control:** The device offers extensive programmability for each channel. Engineers can adjust gain (1.0 to 1.5x) and offset (±500 mV) to compensate for source variations and system-level offsets. The internal clamp circuit fixes the back porch of the video signal to a known reference level, ensuring accurate black level representation.
* **2.5V or 3.3V CMOS Outputs:** The digital outputs are compatible with standard 3.3V logic but can also be powered by a 2.5V supply for reduced power consumption and lower noise.
* **Low Power Consumption:** Despite its high performance, the AD9887 is designed for power efficiency, typically consuming 500 mW when operating at 170 MSPS with a 3.3V supply.
**Primary Applications and System Integration**
The primary function of the AD9887AKSZ-170 is to serve as the bridge between the analog video world and the digital processing domain. Its main applications include:
* **LCD Monitors and Digital Televisions:** It is a key component in the analog input stage of flat-panel displays, digitizing the VGA signal from a computer or legacy device.
* **Digital Projectors and Multimedia Interfaces:** It enables projectors to accept and process standard analog computer video signals.
* **Video Processing and Scan Conversion Systems:** Used in systems that require digitization of analog video for scaling, filtering, or format conversion.
In a typical application circuit, the analog RGB signals are AC-coupled into the respective input channels. The HSYNC and VSYNC signals are provided to the sync processing logic. The internal PLL uses the HSYNC input to generate the sampling clock. The device is controlled via an I²C serial interface, allowing a system microcontroller to easily configure all parameters, including gain, offset, clamp positioning, and PLL operating modes. Proper **PCB layout with a dedicated ground plane** is crucial for maintaining signal integrity and achieving the specified high-speed performance.
**Design Considerations**
Successful implementation requires attention to several key areas:
1. **Power Supply Decoupling:** Use high-quality decoupling capacitors placed as close as possible to the power pins to suppress noise.
2. **Analog Input Management:** Ensure proper termination and use high-bandwidth op-amps for input buffering if necessary. The quality of the input signal directly impacts digital output fidelity.
3. **Clock Integrity:** Minimize noise on the PLL power supply and reference voltage pins to reduce clock jitter, which directly affects ADC accuracy.
4. **Thermal Management:** While power-efficient, the device should be placed in an area with adequate airflow, especially in enclosed systems.
ICGOODFIND: The **AD9887AKSZ-170** stands as a robust and highly integrated solution for high-resolution analog-to-digital video conversion. Its combination of **high-speed performance (170 MSPS), on-chip PLL, and extensive programmability** makes it an ideal choice for designers building high-quality display and video processing systems that must interface with legacy analog video sources. Its well-documented architecture and support simplify the design-in process, ensuring reliable operation in demanding applications.
**Keywords:** Analog-to-Digital Converter (ADC), Phase-Locked Loop (PLL), 170 MSPS, Analog Video Interface, I²C Programmable
