LDTC 2SLASH2E datasheet(10/25 Pages) WAVELENGTH

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LDTC2/2 LASER DIODE DRIVER AND TEMPERATURE CONTROLLER

POWER SUPPLY SELECTION

The V

DD voltage supply input is common to both the

WLD33ND and the WTC32ND. This supply furnishes the

voltage to the control electronics of the devices as well as

the compliance voltage for the WLD33ND laser driver.

The supply should be capable of providing at least 3.0 A

of current in applications that use a separate V

S supply

in the temperature control implementation. Temperature

control applications that tie V

DD and VS together require a

DD current capacity that equals the sum of the maximum

TEC or Resistive Heater current, plus the maximum laser

diode current, plus approximately 200 mA for the control

electronics of the WTC32ND temperature controller and the

WLD33ND laser driver, plus current to an optional fan. Using

the maximum potential of the WLD and WTC will not require

more than 6.0 A.

S is the voltage that is applied to the TEC or Resistive

Heater. This voltage should be high enough to supply the

voltage required by the TEC or Resistive Heater plus the

compliance required by the WTC. The voltage available to

the TEC will be from between 0.5 to 1.8 V lower than V

S. To

minimize power dissipation in the WTC, keep V

S as low as

possible.

Calculate the maximum internal power dissipation of your

design

before applying power to the LDTC2/2. There are

Safe Operating Calculators available on our website.

TEMPERATURE SETPOINT

Wavelength introduces a special setpoint circuit with the

LDTC2/2. An onboard trimpot (TSET) will adjust the voltage

from 0.3 to 2.5 V. Additionally, Pins 11 (R TC SET) &

12 (COM) of Connector J2 will accept a DAC voltage (from

0.3 to 2.5 V). The new feature - the “Failsafe Setpoint” will

default the setpoint to 1 V (~25°C for a 10 kΩ thermistor) if

the chosen signal (from the onboard trimpot or DAC) falls

below 0.3 V.

A jumper (ExtTset) lets you choose to use only the

on-board potentiometer or the external voltage, as shown in

Figure 7 below.

Use On-board

trimpot

Sum ExtTset with

trimpot

Use External

Voltage only

ExtTset Vset PDset

Figure 7. Source of setpoint.

The ExtTset jumper configures the Remote Temperature

Setpoint choice. There is approximately 100 mV of

hysteresis built into the default voltage. The input impedance

of R TC SET is greater than 20 kΩ and is fully buffered. If

you use a different sensor or would prefer a different default

voltage, contact Wavelength.

MONITOR ACTUAL TEMPERATURE & SETPOINT

Pins 9 & 10 of Connector J2 are ACT T MONitor

and SET T MONitor, respectively. Measure the actual

sensor voltage across Pin 9 and Pin 12 (COM). For a 10 kΩ

thermistor with the default 100 μA bias current, the resistance

(in kΩ) is given by:

R = 10 · V

J2_PIN9

To monitor the setpoint voltage used by the WTC, use Pins

10 and 12.

ENABLE CURRENT TO TEC

Output current is supplied to the load as soon as power is

applied to the controller. The Power LED indicator will light

GREEN when power is applied.

LDTC 2/2E Datasheet(PDF) 10 Page - Wavelength Electronics, Inc.

LDTC 2/2E Datasheet(HTML) 10 Page - Wavelength Electronics, Inc.

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