lda1-cp2 Analog Technology, Inc., lda1-cp2 Datasheet - Page 4

• Manufacturer Part Number: lda1-cp2
• Description: Dual Mode Laser Driver
• Manufacturer: Analog Technology, Inc.

when the laser is outputting the desired power. The laser is
now operating at a constant power mode. When the
temperature changes for too much, after years’ operation, or
by some fault, the laser may be turned to current mode. Even
at that time, the laser will at most be receiving 1.2 times the
NOC, which will not damage the laser.
MODE SETTING
A. Set the driver to constant current mode without over
power protection
In this mode, the laser is always operating at constant current
mode.
B. Set the driver to constant current mode with over
power protection
In this mode, the laser is operating at the constant current
mode until the laser output power reaches the preset
maximum power, the protection power, when this happens,
the laser will be operating in a constant power mode.
5 50 E. Weddell Drive, Suit e 4, Sunnyvale, CA 94 08 9, U. S. A. Tel.: (4 08 ) 7 47 -9 76 0, Fax: [phone] , W eb: w w w .analogt echnologies.com
 Copyrights 2000 – 2009, Analog Technologies, Inc. All Rights Reserved. Updated on 9/11/2009
1. Set
2. Make sure that LPS is higher than LPO. This can be
1. Set
2. Set LPS to the voltage generated at the LPO pin by
LIS = 1.2 × LIO
where I
done by connecting LPS (pin 8) to the voltage
reference 2.5V, pin 5, and PDA (pin 11) to LPO
(pin 10).
where I
the internal TIA when the laser is outputting the
protection power level. The TIA converts the
current of the power-sensing PD (Photo Diode) into
a voltage, with the gain set by an external resistor
connected between the PDA and GND pins. Make
Analog Technologies
laser
laser
LIS = 2.5V × I
LIS = 2.5V × I
is the set-point laser current.
is the set-point laser current.
laser
laser
/2.0A,
/2.0A,
C. Set the driver to constant power mode without over
current protection
In this mode, the laser is always operating in the constant
power mode (up to the maximum rated current of 2.0A).
D. Set the driver to constant power mode with over
current protection
In this mode, the laser is operating in the constant power
mode unless the laser current reaches a predetermined
protection current. When the laser reaches the protection
current, the laser will be operating in constant current mode.
1. Connect LIS to 2.5V reference pin.
2. Set LPS to the voltage value which is generated at
1. Set
2. Set LPS to the voltage value which is generated at
sure that the set-point laser current is at least 5%
less than the current needed to generate the
protection laser power level.
the LPO pin by the internal TIA (Trans-Impedance
Amplifier) when the laser is outputting the set-point
power. The TIA converts the current of the power-
sensing PD (Photo Diode) into a voltage, with the
gain set by an external resistor connected between
the PDA and GND pins. Make sure that the laser
can output the set-point power by a current of less
than 1.90A.
where I
the LPO pin by the internal TIA (Trans-Impedance
Amplifier) when the laser is outputting the set-point
power. The TIA converts the current of the power-
sensing PD (Photo Diode) into a voltage, with the
gain set by an external resistor connected between
the PDA and GND pins. Make sure that the laser
can output the set-point power by a current of less
than 95% of the protection current.
protect
Dual Mode Laser Driver
LIS = 2.5V × I
is the predetermined protection current.
protect
/2.0A,
LDA1-CP2
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