cxa1992r Sony Electronics, cxa1992r Datasheet - Page 29
cxa1992r
Manufacturer Part Number
cxa1992r
Description
Rf Signal Processing Servo Amplifier
Manufacturer
Sony Electronics
Datasheet
1.CXA1992R.pdf
(49 pages)
Commands
The input data to operate this IC is configured as 8-bit/12-bit data; however, below, this input data is
represented by 2-digit hexadecimal numerals in the form $XX, where X is a hexadecimal numeral between 0
and F/$XXX for 12-bit.
Commands for the CXA1992R can be broadly divided into four groups ranging in value from $0X, $1X, $2X,
$3XX.
1. $0X (FZC at SENS1 pin (Pin 25), H (Hi-Z) at SENS2 pin (Pin 26))
These commands are related to focus servo control.
The bit configuration is as shown below.
Four focus related switches exist: FS1, FS2, FS4 and DFCT.
$00
$02
$03
By alternating the commands between $02 and $03, the focus search voltage can be constructed. (Fig. 2)
Fig. 2. Constructing the search voltage by alternating between $02 and $03. (Voltage at Pin 6)
D7
0
When FS1 = 0, Pin 8 is charged to (22µA – 11µA)
If, in addition, FS2 = 0, this voltage is no longer transferred, and the output at Pin 6 becomes 0V.
From the state described above, the only FS2 becomes 1. When this occurs, a negative signal is output
to Pin 6. This voltage level is obtained by equation 1 below.
(22µA – 11µA)
The SRCH DOWN speed can be increased by the charge up circuit.
From the state described above, FS1 becomes 1, and a current source of +22µA is split off.
Then, a CR charge/discharge circuit is formed, and the voltage at Pin 8 decreases with the time as
shown in Fig. 1 below.
This time constant is obtained with the 50k resistance and an external capacitor.
D6
0
50k
D5
0
Fig. 1. Voltage at Pin 8 when FS1 goes from 0
0V
$
resistance between Pins 6 and 7
00 02
D4
0
0V
03
FS4
50k
D3
02
– 29 –
D2
—
50k = 0.55V.
03
FS2
.... Equation 1
D1
02
00
FS1
D0
1
CXA1992R