ADNS-7550 Avago Technologies US Inc., ADNS-7550 Datasheet - Page 8

• Manufacturer Part Number: ADNS-7550
• Description: Optical Mouse Sensor,DIP
• Manufacturer: Avago Technologies US Inc.

Specifications of ADNS-7550

• Mounting Style: Through Hole
• Termination Style: Solder Pin
• Supply Voltage: 5 V
• Operating Temperature Range: 0 C to + 40 C
• Product: Optical
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Other names: 516-2180; ADNS-7550

Disabling the LASER
LASER_NEN is connected to the gate of a P-channel
MOSFET transistor which when ON connects RefB to the
LASER. In normal operation, LASER_NEN is low. In the
case of a fault condition (ground or RefB at XYLASER),
LASER_NEN goes high to turn the transistor off and dis-
connect RefB from the LASER.
Single Fault Detection
ADNS-7550 is able to detect a short circuit or fault
condition at the XYLASER pin, which could lead to
excessive laser power output. A path to ground on this
Figure 7. Single Fault Detection and Eye-safety Feature Block Diagram
8
Microcontroller
Serial port
voltage sensor
fault control
current set
block
DRIVER
LASER
ADNS-7550
VDD3
pin 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
components as shown in the block diagram below, the
system will prevent excess laser power for a resistive
path to ground at XYLASER by shutting off the laser. In
addition to the ground path fault detection described
above, the fault detection circuit is continuously
checking for proper operation by internally generating a
path to ground with the laser turned off via LASER_NEN.
If the XYLASER pin is shorted to V
will fail and will be reported as a fault.
GND
VCSEL
LASER_NEN
XYLASER
VCSEL-VE
VCSEL+VE
DD5
G
Ref B
S
D
/RefA/RefB, this test