PixArt Imaging Inc.

PAW3602DH

CMOS Laser Mouse Sensor

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PixArt Imaging Inc.

V1.0, Jun. 2007

2. Block Diagram and Operation

Figure 3. Block Diagram

The PAW3602DH is a high performance CMOS laser mouse sensor with DSP integration chip that serves as a non-

mechanical motion estimation engine for implementing a computer mouse. It is based on new laser speckle

navigation technology. In the laser mouse, it uses laser diode (LD), specially uses VCSEL (Vertical Cavity Surface

Emitting Laser) as light source, where laser is one kind of coherent light. When this light illuminates on the working

surface, the surface will reflect and diffuse the incident light and generates speckle pattern. The imaging sensor in the

laser mouse chip detects the speckle pattern that generated from the working surface and determines the movement

and direction. Since the speckle pattern can be generated on the most of the surface if this surface is not perfect

smooth or transparent, the laser mouse can adapt on more surfaces as compared with traditional LED-based optical

mouse.

The PAW3602DH has an extra function, eye safety protection circuit. The embedded eye safety protection

circuit will detect if LD_P pin is short to power, if LD_N pin is short to ground, or if LD_RES pin is short to

ground to be a large LD power. And this will protect users from eye injured for large LD power. This mouse

sensor is in a 20-pin optical package. The output format is two-channel quadrature (X and Y direction), which

emulates encoder phototransistors. The current X and Y information are also available in registers accessed via a

serial port. The word "mouse sensor," instead of PAW3602DH, is used in the document.