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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

Ω.

(5) Modulator Level Adjustment

The modulator level adjustment can be performed by varying the IIN1 input current value.

Modulator OFF

IIN1 – Input current [A]

IIN1 input current [A]

0

Modulator amplitude

RAMP resistance value [

Ω]

Modulator level adjustment

Imod

Iread

Iread = IIN1

× 104

RAMP pin voltage (1.26V)

RAMP external resistance value

Imod

≈

× 200

Iread < 1/2Imod

Iread < 1/2Imod

1/2Imod