cxa2640er Sony Electronics, cxa2640er Datasheet - Page 9

• Manufacturer Part Number: cxa2640er
• Description: 3-channel 2-ld Driver For Optical Disc Drive
• Manufacturer: Sony Electronics

CXA2640ER
Description of Operation
(1) LD Drive Current Value Setting
The current controlled by the current setting pins IIN1, IIN2 and IIN3 is output from the LDOUT1 and LDOUT2
pins. IIN1, IIN 2 and IIN3 can be set respectively by LDEN1, LDEN2, OUTEN and xOUTEN for the output drive
current from the LDOUT pin.
(2) Differential Input and Single-end Input
External processing is required for the differential input and single-end input switching.
For the single-end input, if the device is used at the active Low, the OUTENREF pin and the OUTEN pin
should be shorted externally; if it is used at the active High, the OUTENREF pin and the xOUTEN pin should
be shorted externally. Leave the OUTENREF pin open for the differential input.
(3) Modulator Circuit
The modulator ON/OFF is controlled by the OSCEN pin.
For the DVD side, the modulator frequency is varied by the external resistor connected to the RFREQ1 pin and
the modulator amplitude can be varied by the external resistor value connected to the RAMP1 pin.
For the CD side, the modulator frequency is varied by the external resistor connected to the RFREQ2 pin and
the modulator amplitude can be varied by the external resistor value connected to the RAMP2 pin.
(4) RFREQ COMP Pin
The current depending on the internal resistor is generated using the RFREQ COMP pin external resistor to
suppress the dispersion of the modulator frequency depending on the internal resistor.
The RFREQ COMP pin external resistor is recommended to be fixed to 22k .
(5) Modulator Level Adjustment
The modulator level adjustment can be performed by varying the IIN1 input current value.
Modulator OFF
Modulator amplitude
Modulator level adjustment
Imod
Iread
0
RAMP resistance value [ ]
IIN1 – Input current [A]
IIN1 input current [A]
1/2Imod
RAMP pin voltage (1.26V)
Iread = IIN1
104
200
Imod
Iread < 1/2Imod
Iread > 1/2Imod
RAMP external resistance value
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