wm8215 Wolfson Microelectronics plc, wm8215 Datasheet - Page 13

• Manufacturer Part Number: wm8215
• Description: 60msps 10-bit 3-channel Ccd Digitiser
• Manufacturer: Wolfson Microelectronics plc

WM8215
DEVICE DESCRIPTION
INTRODUCTION
INPUT SAMPLING
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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.
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.
PD, Rev 4.2, February 2009
Production Data
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