HA12220 データシートの表示（PDF） - Hitachi -> Renesas Electronics

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HA12220

CD-ROM Drive Head Amplifier IC

Hitachi -> Renesas Electronics 

HA12220F

Focus Error Amplifiers

The FE amplifier adds and subtracts the output from the PDIC.

FVR2 is a variable resistor used to increase the gain by 12dB in CD-RW mode. This variable resistor is set

by 1-bit data from the HD49250.

FVR is a variable resistor that changes the focus error gain over the range –8 to +8dB in ±4dB steps. This

variable resistor is set by 3-bit data from the HD49250.

An offset of between –0.7 and 0.7V (in 0.1V steps) is inserted into the focus error signal. This is set by 4-

bit data from the HD49250. The FE output cut-off frequency (fc) is 60kHz Typ.

28 RF1 160k

1 RF2 160k

2 RF3

3 RF4 160k

160k

10p

10p

160k

–

+

FE

160k

+FA2

–

Gain=12dB Typ

+FA

FVR2

–

160k

FVR

9

10p

FE

Offset

Figure 8 Focus Error Amplifiers

Defect Detection Circuit

When a scratched disc is played, the EFM RF signal has the shape shown in figure 10 (a). The defect

detection circuit detects the drop-out area of this signal.

from AGC

0.015µ

21

DFH

DEFECT

MIRR

DFT 20

HD49250

MIRH 19

0.033µ

MIRR 18

HD49250

Figure 9 Mirror Detection, Defect Detection

(a) Pin 22

(b) Pin 20

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Figure 10 Defect Detection Waveform

Rev.1, Apr. 1997, page 12 of 20

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