PixArt Imaging Inc.
ADNS-7550 Integrated Molded Lead-Frame DIP Sensor
LASER Drive Mode
The laser is driven in pulsed mode during normal
operation. A calibration mode is provided which drives
the laser in continuous (CW) operation.
7.
Program registers 0x1c and 0x1d with increasing
values to achieve an output power of not more than
506uW to meet class 1 Eye Safety over temperature.
If this power is obtained, the calibration is complete,
skip to step 11.
If it was not possible to achieve the power target, set
the laser current to the minimum value by writing
0x00 to register 0x1c, and the complementary value
0xff to register 0x1d.
Set the Range and Range_C bits in registers 0x1a
and 0x1f, respectively, to choose to the higher laser
current range.
Eye Safety
The ADNS-7550 integrated molded lead-frame DIP
sensor and the associated components in the schematic
of Figure 5 are intended to comply with Class 1 Eye
Safety Requirements of IEC 60825-1.
PixArt Imaging
suggests that manufacturers perform testing to verify
eye safety on each mouse. It is also recommended to
review possible single fault mechanisms beyond those
described below in the section “Single Fault Detection”.
Under normal conditions, the sensor generates the drive
current for the VCSEL.
In order to stay below the Class 1 power requirements,
LASER_CTRL0 (register 0x1a), LASER_CTRL1 (register
0x1f ), LSRPWR_CFG0 (register 0x1c) and LSRPWR_CFG1
(register 0x1d) must be programmed to appropriate
values. The ADNS-7550 integrated molded lead-frame
DIP sensor which comprised of the sensor and VCSEL;
is designed to maintain the output beam power within
Class 1 requirements over components manufacturing
tolerances and the recommended temperature range
when adjusted per the procedure below and implement-
ed as shown in the recommended application circuit of
Figure 6. For more information, please refer to Eye Safety
Application Note AN 5361.
8.
9.
10. Program registers 0x1c and 0x1d with increasing
values to achieve an output power of not more than
506uW to meet class 1 Eye Safety over temperature.
11. Save the value of registers 0x1a, 0x1c, 0x1d, and
0x1f in non-volatile memory in the mouse. These
registers must be restored to these values every
time the ADNS-7550 is reset.
12. Reset the mouse, reload the register values from
non-volatile memory, enable Calibration mode,
and measure the laser power to verify that the
calibration is correct.
Good engineering practices such as regular power meter
calibration, random quality assurance retest of calibrated
mice, etc. should be used to guarantee performance, reli-
ability and safety for the product design.
LASER Power Adjustment Procedure
1.
2.
3.
4.
5.
The ambient temperature should be 25C +/- 5C.
Set V
DD5
to its permanent value.
Set the Range bits (bit 7 and 6 of register 0x1f ) to
b’01.
Set the Range_C1 and Range_C0 complement bits
(bit 7 and 6 of register 0x1f ) to b’10.
Enable the Calibration mode by writing to bits [3,
2, 1] of register 0x1A so the laser will be driven with
100% duty cycle.
Set the laser current to the minimum value
by writing 0x00 to register 0x1c, and the
complementary value 0xFF to register 0x1d.
LASER Output Power
The laser beam output power as measured at the naviga-
tion surface plane is specified below. The following con-
ditions apply:
1.
2.
3.
The system is adjusted according to the above
procedure.
The system is operated within the recommended
operating temperature range.
No allowance for optical power meter accuracy is
assumed.
6.
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PixArt Imaging Inc.
E-mail:
fae_service@pixart.com.tw
7
PIXART [ PIXART IMAGING INC. ]
