WM8215

Production Data

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PD, Rev 4.3, September 2012

13

DEVICE DESCRIPTION

INTRODUCTION

A block diagram of the device showing the signal path is presented on the front page of this

datasheet.

The WM8215 samples up to three inputs (RINP, GINP and BINP) simultaneously. The device then

processes the sampled video signal with respect to the video reset level or an internally/externally

generated reference level using between one and three processing channels.

Each processing channel consists of an Input Sampling block with optional Reset Level Clamping

(RLC) and Correlated Double Sampling (CDS), an 8-bit programmable offset DAC and a 9-bit

Programmable Gain Amplifier (PGA).

The processing channel outputs are switched alternately by a 3:1 multiplexer to the ADC input.

The ADC then converts each resulting analogue signal to a 10-bit digital word. The digital output from

the ADC is presented in parallel on the 10-bit wide output bus, OP[9:0]. The ten output pins can be

set to a high impedance state using either the OEB control pin or the OPD register bit.

On-chip control registers determine the configuration of the device, including the offsets and gains

applied to each channel. These registers are programmable via a serial interface.

INPUT SAMPLING

The WM8215 can sample and process up to three inputs through one to three processing channels

as follows:

Colour Pixel-by-Pixel: The three inputs (RINP, GINP and BINP) are simultaneously sampled for

each pixel and a separate channel processes each input. The signals are then multiplexed into the

ADC, which converts all three inputs within the pixel period.

Two Channel Pixel-by-pixel: Two input channels (RINP and GINP) are simultaneously sampled for

each pixel and a separate channel processes each input. The signals are then multiplexed into the

ADC, which converts both inputs within the pixel period. The unused Blue channel is powered down

when this mode is selected.

Monochrome: A single chosen input (RINP, GINP, or BINP) is sampled, processed by the

corresponding channel, and converted by the ADC. The choice of input and channel can be changed

via the control interface, e.g. on a line-by-line basis if required. The unused channels are powered

down when this mode is selected.