
9
LASER Drive Mode
The LASER has 2 modes of operation: DC and Shutter. In
DC mode, the LASER is on at all times the chip is powered
except when in the power down mode via the NPD pin.
In shutter mode the LASER is on only during the portion
of the frame that light is required. The LASER mode is
set by the LASER_MODE bit in the Conguration_bits
register. For optimum product lifetime, Avago recom-
mends the default Shutter mode setting (except for cali-
bration and test).
Eye Safety
The ADNS-7010 and the associated components in the
schematic of Figure 7 are intended to comply with Class
1 Eye Safety Requirements of IEC 60825-1. Avago Tech-
nologies 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 ADNS-7010 generates the
drive current for the laser diode (ADNV-6340). In order to
stay below the Class 1 power requirements, resistor Rbin
must be set at least as high as the value in the bin table of
Figure 7, based on the bin number of the laser diode and
LP_CFG0 and LP_CFG1 must be programmed to appropri-
ate values. Avago recommends using the exact Rbin value
specied in the bin table to ensure sucient laser power
for navigation. The system comprised of the ADNS-7010
and ADNV-6340 is designed to maintain the output beam
power within Class 1 requirements over component man-
ufacturing tolerances and the recommended tempera-
ture range when adjusted per the procedure below and
when implemented as shown in the recommended ap-
plication circuit of Figure 7. For more information, please
refer to Application Note AN5088 on the eye safety calcu-
lation.
LASER Power Adjustment Procedure
1. The ambient temperature should be 25°C +/- 5°C.
2. Set VDD3 to its permanent value.
3. Ensure that the laser drive is at 100% duty cycle.
4. Program the LP_CFG0 and LP_CFG1 registers to
achieve an output power as close to 506uW as possible
without exceeding it.
Good engineering practices should be used to guarantee
performance, reliability and safety for the product design.
Avago has additional information and detail, such as
Parameter Symbol Minimum Maximum Units Notes
Laser output power LOP 716 µW Per conditions above
rmware practices, PCB layout suggestions, and manu-
facturing procedures and specications that could be
provided.
LASER Output Power
The laser beam output power as measured at the naviga-
tion surface plane is specied below. The following con-
ditions apply:
1. The system is adjusted according to the above
procedure.
2. The system is operated within the recommended
operating temperature range.
3. The VDD3 value is no greater than 50mV above its value
at the time of adjustment.
4. No allowance for optical power meter accuracy is
assumed.
Disabling the LASER
LASER_NEN is connected to the base of a PNP transistor
which when ON connects VDD3 to the LASER. In normal
operation, LASER_NEN is low. In the case of a fault
condition (ground at XY_LASER or RBIN), LASER_NEN goes
high to turn the transistor o and disconnect VDD3 from
the LASER.
Single Fault Detection
ADNS-7010 is able to detect a short circuit, or fault,
condition at the RBIN and XY_LASER pins, which could
lead to excessive laser power output. A low resistance
path to ground on either of these pins will trigger the
fault detection circuit, which will turn o the laser drive
current source and set the LASER_NEN output high.
When used in combination with external components
as shown in the block diagram below, the system will
prevent excess laser power for a single short to ground at
RBIN or XY_LASER by shutting o the laser. Refer to the PC
board layout notes for recommendations to reduce the
chance of high resistance paths to ground existing due to
PC board contamination.
In addition to the continuous fault detection described
above, an additional test is executed automatically
whenever the LP_CFG0 register is written to. This test
will check for a short to ground on the XY_LASER pin, a
short to VDD3 on the XY_LASER pin, and will test the fault
detection circuit on the XY_LASER pin.