la9251m Sanyo Semiconductor Corporation, la9251m Datasheet - Page 14

• Manufacturer Part Number: la9251m
• Description: Cd Player Analog Signal Processor Asp
• Manufacturer: Sanyo Semiconductor Corporation

10. Focus Detection
11. Defect Detection
12. Oscillator Circuit
The pickup is seen as being in focus when, after a VR + 0.2 V level is detected in the focus error signal S-curve, that
S-curve next goes to the VR level.
The mirror surface level is held by the capacitor on LF2 (pin 59), and DEF (pin 51) goes high if a drop in the EFM
signal (RF output) exceeds about 0.35 V. When DEF goes high, the tracking servo goes to THLD mode. When a
defect is detected applications can prevent the LA9251M from going to THLD mode either by setting DEF to low or
by setting LF2 (pin 59) low and thus setting the LA9251M not to output DEF.
The oscillator frequency is set by the external RC circuit attached to OSC (pin 31). This oscillator frequency is used
as the reference clock for focus search and E/F balance adjustment.
EFM signal
(RFSM output)
LF2 (pin 59)
DEF (pin 51)
LA9251M
Focus
0.35 V
REF + 0.2 V
A12226
A12227
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