SAF7849HL/M295,557 NXP Semiconductors, SAF7849HL/M295,557 Datasheet - Page 53

• Manufacturer Part Number: SAF7849HL/M295,557
• Description: IC AUD DECODER 144LQFP
• Manufacturer: NXP Semiconductors
• Type: Audio Decoderr

Specifications of SAF7849HL/M295,557

• Applications: Audio CD
• Voltage - Supply, Analog: 3 V ~ 3.6 V
• Voltage - Supply, Digital: 1.8V, 3.3V
• Mounting Type: Surface Mount
• Package / Case: 144-LQFP
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant, Lead free / RoHS Compliant
• Other names: 935287932557

NXP Semiconductors
SAF784X_2
Product data sheet
6.6.4.1 Focus start-up
6.6.4.2 Focus position control loop
6.6.4 Focus servo system
The start-up behavior of the focus controller is influenced by five initially loaded
coefficients. The automatically-generated triangular voltage can be influenced by
three parameters: height (ramp_height), DC offset (ramp_offset) of the triangle, and its
steepness (ramp_incr).
For protection against detection of false focus points, two parameters are available which
are an absolute level on the CA signal (CA_start) and a level on the FE
Focus is achieved when this CA level is reached.
When focus is achieved and the level on the FE
enabled to switch on when the next zero crossing is detected in the FE
The focus control loop contains a digital PID controller which has five parameters
available to the user. These coefficients influence integrating (foc_int), proportional
(foc_lead_length, part of foc_parm3) and differentiating (foc_pole_lead, part of
foc_parm1) action of the PID and a digital low-pass filter (foc_pole_noise, part of
foc_parm2) following the PID. The fifth coefficient, foc_gain influences the loop gain.
Figure 30
determine its behavior.
Fig 29. Detector arrangement
shows the transfer function of the controller, and the coefficients which
single foucault
One chip CD audio device with integrated MP3/WMA decoder
Rev. 02 — 9 May 2008
SATELLITE
SATELLITE
DIODE R1
DIODE R2
D3
D1
D2
astigmatic focus
SATELLITE
SATELLITE
DIODE R1
DIODE R2
D2
D4
D1
D3
n
signal is reached, the focus PID is
double foucault
SATELLITE
SATELLITE
DIODE R1
DIODE R2
001aag333
D1
D2
D3
D4
n
SAF784x
n
© NXP B.V. 2008. All rights reserved.
signal (FE_start).
signal.
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