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12
FL591FL LASER DIODE DRIVER
ADJUST THE PHOTODIODE CURRENT RANGE
The maximum photodiode current input is 1 mA, but the
range can be adjusted by changing a resistor on the
FL591FL circuit board. The location of the resistors is shown
in
Figure 7.
The default resistor value is 1 kΩ ±1%.
Figure 7. Photodiode Feedback Resistors
GND
LIM 1 LIM 2
LDA
LDA
PDA
PDA
LDC
LDC
LD 1
LD 2
]S
]P
RPD1
RPD2
FL500
Channel 1
PD Resistor
Channel 2
PD Resistor
Calculate new resistor values based on the expected
maximum photodiode current using this equation:
R
PD
= 1 / I
PMON
(Ω)
To convert the V
PMON
value to photodiode current, use this
equation:
I
PMON
= V
PMON
/ (2 * R
PD
)
(A)
TECHNICAL SUPPORT
INFORMATION
This section includes useful technical information on these
topics:
•
Adjust the Photodiode Current Range
•
FL591FL Schematic
•
Safe Operating Area Calculation
