WM8170 datasheet(28/41 Pages) WOLFSON

28 / 41 page

WM8170

Product Preview Rev 1.0

WOLFSON MICROELECTRONICS LTD

PP Rev 1.0 March 2000

PROGRAMMABLE THRESHOLD DETECT OUTPUT

The Programmable Threshold Detect Output, (PTDO), primary function is to indicate to the user

when the ADC output has exceeded a value programmed into the THRES[9:0] registers via the

Management Interface. The PTDO output will output a high state, which is aligned to the output data,

if the ADC output exceeds the programmed value. Typically this pin would be used in conjunction

with external gain calibration algorithms to set the PGA gain.

The PTDO output can also be used to indicate a number of system error flags which are available to

the user. These flags are multiplexed onto the PTDO pin under control of the Management Interface.

An error can be flagged if the pixel data during the black pixels is outside the correction range of the

logic within the WM8170, or if the BLCENB pin has returned high before both the analogue and

digital DC correction circuitry has completed their tasks. An error can also be flagged if the output

from the ADC is out of range, i.e. the ADC output code is trying to exceed 3FF(hex), or be less than

0(hex).

The error flag can be programmed to be output on the PTDO pin under control of the register bits

PTDO[1:0].

AUXILIARY DIGITAL TO ANALOGUE CONVERTERS

The WM8170 includes two independent 8-Bit Digital to Analogue Converters. Their analogue outputs

are available at pins VOUT1 and VOUT2 respectively. Their output voltages are controlled in two

ways. The maximum output voltage from the DACs can be independently set to be either AVDD or

AVDD/2 under control of the AUX1X1 and AUX2X1 control bits. Each DAC can then be programmed

to one of 256 codes by the 8-bit contents of the Auxiliary DAC registers defined in the register map

shown in Table 15.

These DACs can be used to trim CCD control voltages such as the anti-blooming or reset gate bias

voltages, or used within the camera system for features such as auto-focus.

WM8170 Datasheet(PDF) 28 Page - Wolfson Microelectronics plc