CXA2610N Ver la hoja de datos (PDF) - Sony Semiconductor

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Fabricante

CXA2610N

Laser Driver

Sony Semiconductor 

CXA2610N

Notes on Operation

• Locate the external resistors connected to the IINR, IIN2 and IIN3 pins close to the IC package to prevent the

effect from other signal lines.

• Make the wiring distance between the output LD0 pin and the laser diode as short as possible.

If this wiring is longer, the output waveform characteristics show that the rise and fall times (Tr and Tf)

become slower as the ringing becomes larger.

• The external resistor connected to Pin 10 (OSCGA) should be within the range from 12Ω to 2kΩ.

In addition, this resistance value should be set in consideration of the laser diode Ith so that the oscillation

level at IINR = 0V does not exceed the read power.

• Temperature assurance

The junction temperature for the CXA2610N laser driver should not exceed 150°C. In addition, the power

consumption (PO) should be the allowable power dissipation (PD) or less, and the IC should be used with a

lowered thermal resistance (θj-a) for board mounting so that normal operation is possible at the maximum

operating temperature of 70°C.

Widening the GND area on the set board and other heat radiation countermeasures within the set are

necessary in order to lower θj-a.

This is because the CXA2610N thermal resistance (θj-a) differs according to the board, and the power

consumption (PO) is also difficult to predict with future increases in power.

Obtain the thermal resistance (θj-a) and power consumption (PO) of the package by the following method.

Power consumption (PO): Oscillator ON state (OSC level = 47mAp-p)

PO = (ICC2 + (total of each input current × 10)) × VCC + (IOP × (VCC – VOP))

ICC2: See page 3 of this Data Sheet.

IOP: Output drive current flowing from the LD0 pin to the laser diode

VOP: Laser diode operating voltage

or, the power consumption can also be obtained as follows.

PO = (ICC × VCC) – (IOP × VOP)

ICC: Device current consumption (including IOP) during operation

Thermal resistance (θj-a) when mounted on a board

The diode temperature coefficient is –2.27mV/°C

(1) ENABLE pin voltage – VCC pin voltage after applying 0V to the IINR, IIN2 and IIN3 pins = V1

(2) ENABLE pin voltage – VCC pin voltage immediately after applying 3V to IINR = V2

(3) ENABLE pin voltage – VCC pin voltage after applying 3V to the IINR pin and reaching a

thermally balanced state = V3

The change in current consumption between (1) and (2) ∆ICC = (3V/(Rext + 250Ω)) × 104.

This ∆ICC causes the ENABLE pin internal forward protective diode connection VCC voltage to vary

(∆VCC) due to the effects of the wiring resistance from the VCC pin voltage which is used as the

reference.

The voltage fall coefficient (VR) used to correct this ∆VCC can be obtained by VR = (V1 – V2)/∆ICC.

Using VR to apply correction to V3 yields the equation:

(∆ICC × VR) + V3 = V4.

From this, ∆Tj = (V4 – V2) mV/–2.27mV/°C, and θj-a = ∆Tj/PO [°C/W].

• Allowable power dissipation (PD) ≥ PO [W]

PD = (150°C – ambient temperature)/θj-a

• Maximum operating temperature 70 °C

(150°C – ∆Tj) ≥ 70°C

Thus, if θj-a can be lowered from these two conditions, the maximum operating temperature can also

be raised.

VCC

Diode measurement point

11

ENABLE

10

1MΩ

10V

5V

VCC

9

5V

5V

Thermal Resistance Measurement Circuit

–6–

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