LDTC 2SLASH2O datasheet(3/25 Pages) WAVELENGTH

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LDTC2/2 LASER DIODE DRIVER AND TEMPERATURE CONTROLLER

RECOMMENDED THERMOELECTRIC TEST

LOAD

For the temperature controller, recommended simulated

thermoelectric and thermistor circuits are shown in

Figure 5

and

Figure 6. Configuring the temperature controller using

test loads is recommended for setting the thermoelectric

controller limits or to check the temperature controller

operation.

RLOAD

TEC+

(Pin J3-6)

TEC-

(Pin J3-7)

RLOAD = 1 Ω, Rated >10 W

TEC Test Load

IMETER

Figure 5. Simulated Thermoelectric Test Load

R1 = 10 kΩ, ¼ W resistor

SEN-

(Pin J3-9)

SEN+

(Pin J3-8)

Simulated Thermistor

Figure 6. Simulated Thermistor

This circuit simulates a 10 kΩ thermistor operating at 25°C.

Use the 100 µA bias current setting to create a 1 V sensor

signal. Other resistor values can be used depending on

the sensor voltage you wish to simulate. To drive cooling

current, set T SET to 1.35 V and to drive heating current, set

T SET to 0.85 V.

NOTE: To stay within the Safe Operating Area while using

the test load, V

S must not exceed 5 V.

RECOMMENDED LASER DRIVER TEST LOAD

For the laser diode driver, recommended simulated laser

loads are shown in

Figure 3 and Figure 4.

1N4001

LDC

(Pin J3-1)

LDA

(Pin J3-4)

1 Ω, 2 W

Constant Current Mode

Figure 3. Constant Current Mode Test Load

In Constant Power Mode, the setpoint correlates to the

photodiode feedback current, which represents a fraction

of the light power emitted by the laser diode. Photodiode

current is measured by monitoring LD P MON.

24 Ω

1N4001

2N3906

0.33 µF

PDA

(Pin J3-2)

LDA

(Pin J3-4)

LDC

(Pin J3-1)

Constant Power Mode

The 24 Ω resistor typically

produces approximately 30 mA

laser driver current. Vary the

resistor value to change the

output current.

1 Ω, 2 W

Figure 4. Constant Power Mode Test Load

NOTE: To determine the actual drive current, measure

the voltage drop across the 1 Ω resistor. Do not insert an

ammeter in series with the output circuit; doing so may

cause instability in the control loop. To stay within the Safe

Operating Area while using the test load, V

S must not exceed

5 V.

LDTC 2/2O Datasheet(PDF) 3 Page - Wavelength Electronics, Inc.

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