HB7121BELECTRONICS Datasheet, PDF (18/29 Pages) Hynix Semiconductor – CMOS IMAGE SENSOR With 8-bit ADC

Electronics Industries Co., Ltd.
System IC Division
PRELIMINARY
HB7121B
CMOS IMAGE SENSOR
With 8-bit ADC
(11) Operating Clock Divider (Address 28h, default:00h, R/W)
This register generates divided digital clock depending on the settings clk_div [3:0], digital block can
divide MCLK down by 1 through 2048 as shown in Table 1.
clk_div[3:0]
0000
0001
0010
0011
0100
0101
units
no division
MCLK/2
MCLK/4
MCLK/8
MCLK/16
MCLK/32
clk_div[3:0]
0101
0111
1000
1001
1010
1011
units
MCLK/64
MCLK/128
MCLK/256
MCLK/512
MCLK/1024
MCLK/2048
Table 1. Operating Clock Control Register
(12) Reset Level Control Register (Address 30h, default:38h, R/W)
This register controls reference voltage level for start point of data reading. If the register value is
too large or too small, the vertical Fixed Pattern Noise(FPN) can be occurred. To Get rid of FPN,
this register must have a suitable value. Optimum reset revel can be found using Low reference
number registers 57h ~ 58h and High reference number registers 59h ~ 5ah. If there is some large
value in Low reference number registers, the value of Reset Level control register should be
increased. If there is some large value in High reference number registers, the value of register
should be decrease. Optimum reset revel is achieved when value of Low reference level number
registers and value of High reference number registers is minimized.
(13) Color Gain Register
Red Color Gain Register : (Address 31h, default:1Eh, R/W)
Green Color Gain Register : (Address 32h, default:h1Eh, R/W)
Blue Color Gain Register : (Address 33h, default:h1Eh, R/W)
These registers are used to amplify the analog pixel output. If the gain register value is decreased,
the amplification is increased. Therefore under the dark light source condition, the pixel output have
to be amplified by decreasing gain value to get good image. There are three Gain registers to control
RGB colors independently. In the case of monochrome image sensor, use only Green Color Gain
Register. Available program range is 0 ~ 63 but too small value can cause FPN. The register value
have to chosen within the range that doesn’ t cause FPN. Recommended range is 20 ~63. These
register can be used for Auto White Balance control and Auto Exposure control.
This document is a general product description and is subject to change without notice. Hyundai Electronics does not assume
any responsibility for use of circuits described. NO patent licenses are implied.
DA21991011R_1.0
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1999 Hyundai System IC Division