PixArt Imaging Inc.
ADNS-9500 LaserStream™Gaming Sensor
LASER Output Power (LOP)
Single Fault Detection
The LOP can be measured for testing purpose as per steps ADNS-9500 sensor is able to detect a short circuit or fault
below.
condition at –VCSEL pin, which could lead to excessive
laser output power. A leakage path to ground on this
node will trigger the fault detection circuit, which will turn
off the laser drive current source and set the LASER_NEN
output high. When used in combination with external
component as shown in the block diagram below, the
system will prevent excessive laser power for a resistive
path at XY_LASER by shutting off the laser. In addition
to the ground path fault detection described above, the
fault detection circuit is periodically checking for proper
operation by internally generating a path to ground with
the laser turned off via LASER_NEN. If the –VCSEL pin is
shorted to VDD5, VDD3, REFA or REFB pin, this test will fail
and will be reported as a fault.
1. Power up reset the mouse system.
2. Enable the laser by setting Forced_Disabled bit of
LASER_CTRL0 register (address 0x20) to 0.
3. Enable the Calibration mode by writing 010b to bits
[3,2,1] of LASER_CTRL0 register (address 0x20) to set
the laser to continuous (CW) mode.
4. Measure the LOP at the navigation surface plane.
The pre-calibrated LOP value at typical operating supply
voltage and temperature of 25 5ꢀC should not exceeding
506μW, otherwise the LOPmax limit in the Absolute
Maximum Rating is applicable. The following conditions
apply:
The system is operated within the recommended
operating supply voltage and temperature range.
In 3V mode, the VDD3 value is no greater than 300mV
above the pre-calibration voltage of 3.0V. In 5V mode,
REFB should be used to drive the PMOSFET connecting
to VCSEL.
No allowance for optical power meter accuracy is
assumed.
VDD3/REFB
(Pin 12)
ADNS-9500
Microcontroller
S
LASER DRIVER
LASER_NEN
G
P_MOSFET
VDD3
D
fault control
block
VCSEL
Serial port
+VCSEL
–VCSEL
voltage sense
current set
470 pF
GND
Figure 8. Single Fault Detection and Eye-safety Feature Block Diagram
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PixArt Imaging Inc.
E-mail: fae_service@pixart.com.tw
9
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