USBKIT datasheet(14/20 Pages) WAVELENGTH

14 / 20 page

www.teamWavelength.com

PLD10000/PLD12500 LASER DIODE DRIVER

CHANGE THE ANALOG INPUT MODULATION

TRANSFER FUNCTION

The Analog Input Modulation transfer function can be

changed by adding a voltage divider resistor network

external to the PLD driver.

Figure 13 illustrates a simple

circuit.

ANALOG

INPUT

Keep R1 and R2 below 100 kΩ for maximum accuracy.

R2 + R1

New

Transfer

Function

Built-In Transfer Function

Example:

(for PLD10000)

R1 = 9 kΩ

R2 = 1 kΩ

1 + 9

New

Transfer

Function

2.3 A / V = 0.23 A / V

COMMON

Figure 13. Changing the Analog Input

Modulation Transfer Function

EXTERNAL SETPOINT CIRCUIT

An external trimpot circuit can be used to adjust the laser

current setpoint; refer to

Figure 14.

Analog Input

Pin 16

V+5V

Common

Pin 19

= Supply voltage

D1 = Bandgap reference* (LM4040)

R1 = 2.2 k, 1 W resistor

R2 = Trimpot, 10 k to 100 k

must be at least 1 volt greater than

the voltage value of D1.

V+5V

Pin 13, 14, 15

Figure 14. Trimpot Circuit for Analog Input

IMPORTANT INFORMATION ON GROUNDING

Some laser diodes connect the laser anode or cathode to

the case. Pay particular attention to grounding to ensure

safe operation of the PLD and laser.

it is critical that the PlD Driver is ProPerly

grounDeD

. iF the PlD Driver is useD with a

wavelength electronics temPerature controller,

you may neeD to use two seParate Power suPPlies

that Float inDePenDently oF each other

If the laser anode is connected to the laser case, it is possible

that the anode will be connected to earth ground when

the laser is installed in a benchtop mount, or in your laser

system. In situations where the laser diode is connected to

the case, it is critical that the negative terminal of the power

supply remain isolated from earth ground.

FINE TUNE DEEP MODULATION

If the analog modulation input is near the rail (> 4.5 V), output

current signal response may be insufficient. Performance

may be improved by connecting a low-ESR 330 µF,

16 V, electrolytic capacitor between pins 10 and 13. This

decoupling capacitor should be connected at the driver.

CABLE LENGTHS AND HIGH CURRENT

The length and gauge of cable from the power supply or

to the laser diode can impact performance. The resistance

and inductance of the wire can reduce bandwidth or cause

the voltage to the PLD to droop.

Use minimum 14 AWG wire for the laser diode interconnect

wires. Always twist the wire pairs to eliminate reactance.

If the output current starts to oscillate as setpoint voltage

approaches the limit setting, then the power supply cables

may be too long. If you cannot shorten the cables, place a

330 µF capacitor across pins 10 and 13 to minimize droop.

USBKIT Scheda tecnica(PDF) 14 Page - Wavelength Electronics, Inc.

USBKIT Scheda tecnica(HTML) 14 Page - Wavelength Electronics, Inc.

Html Pages

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20

Scheda tecnica Scarica

Link URL