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. . Five-Channel Dual CD/DVD Laser Driver for Ultra Combo Drives CXA2697ER The demands for even higher speeds are increasing inevitably along with the continuing rapid growth in the DVD drive market. The CXA2697ER provides 5 channels to support the increasingly high order multiple-value strategies associated with higher record speeds. The CXA2697ER was developed as a single-function laser driver IC that can set the modulator amplitude according to the media used by incorporating a high-frequency modulator amplitude switching function.

CXA2697ER . . * CD system total maximum drive current: 370 mA * DVD system total maximum drive current: 450 mA * Rise/fall time: 1 ns * Support for strategy in all five channels * Read channel low noise : 1.5 nA/√Hz * High-frequency modulator frequency accuracy: Less than ±10% * Built-in DVD modulator amplitude switching function * Support for various timing signals     Both Higher Output and Higher Speed Achieved While increases in both the output transient waveform speed and the maximum output drive current are required to achieve higher linear velocities, increasing the maximum output drive current requires increasing the size of the output transistors, and this leads to delays of the output transient waveform. The CXA2697ER makes x12-speed DVD recording possible, first by providing the ability to supply the required maximum output drive currents under severe conditions for both CD and DVD as follows: * CD system total maximum drive current: 370 mA (See figure 1.) (Vcc = 3.3 V, VccLD = 5 V, Vop = 2.5 V) * DVD system total maximum drive current: 450 mA (See figure 2.) (Vcc = 3.3 V, VccLD = 5 V, Vop = 3 V), and second, by optimizing the output transient waveform with an internal waveform shaping circuit to be both high speed and to have minimal overshoot. This makes x12-speed DVD recording possible. Read Channel Low Noise To achieve the signal-to-noise ratio required for high linear velocities, Sony adopted thoroughgoing low-noise design techniques in this IC to achieve the low noise level of 1.5 nA/√Hz (at 20 MHz, 35 mA, 20 mAp-p). High-Frequency Modulator Frequency Accuracy In high-frequency modulator, which is used to reduce noise during playback, interference may occur between the return light from the disc surface and the laser beam due to variations in frequency. This can aggravate noise. However, the CXA2697ER reduces noise by canceling the internal resistance dependent frequency variations generated in the VCO, which uses an emitter junction multivibrator. DVD System Modulator Amplitude Switching This function allows applications to set an optimal modulator amplitude for the DVD system media used. Support for Various Timing Signals The CXA2697ER supports both differential inputs (LVDS) for higher speeds and single-ended inputs (3.3 V CMOS/TTL) for the timing inputs. Small Package Adopted The CXA2697ER is provided in a 32-pin VQFN (4.8 mm x 4.8 mm) small package and can contribute to pickup miniaturization by reducing the mounting area. In addition to this small package size, the CXA2697ER also features exposure of the die pads on the package surface. This allows heat dissipation to be improved by close contact between the die pads and a heat sink using silicone grease. Since this prevents the heat from being transmitted to the laser diode through the mounting substrate, it makes an optimal substrate for the laser diode and at the same time also allows wiring on the back side of the IC.     •••• Mr.KAMIEGAWA •••• Since this was my first attempt at developing a laser driver using the BiCMOS process, I had no idea what problems I might run into. However the result, the CXA2697ER, is a product I have great confidence in. I strongly recommend that you consider this device for your next CD/DVD product. See all articles with figures and tables. Vol.36

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