AN-775 Implementing the Auto-Offset Function on the AD9880 Application Note

About this manual

The document describes the implementation of the auto-offset feature on the AD9880 Analog-to-Digital Converter (ADC). This function monitors output during the clamp period to calculate and adjust offset settings automatically. When enabled, specific registers are used as target codes for feedback, while others manage brightness adjustments using two's complement notation.

The guide provides detailed instructions on configuring Register 0x1C to enable auto-offset and setting Target Code Registers (0x09, 0x0B, 0x0D) for different signal types like RGB and YPbPr. It also explains the differences in register definitions between disabled and enabled modes and offers example settings tables.

What's inside

• Introduction
• Auto-Offset Function Overview
• Register Definitions Changes
• Brightness Adjustment
• Using Auto-Offset
• Example Register Settings

Frequently asked questions

What is the effective range for adjusting offset when auto-offset is enabled?

The effective range for adjusting offset is +63/-64 LSBs.

What values must be set in Register 0x1D for proper operation?

Register 0x1D bits 7:0 must be set to OxFF.

To what value should the target code registers normally be programmed for RGB signals?

All three target code registers should normally be programmed to a very small code, such as 4.