Wavelength Technology

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RONAR-SMITH® LASER OPTICS & IR IMAGING

WLD3343
GENERAL DESCRIPTION FEATURES

The WLD3343 is a general-purpose analog hybrid circuit for use in ultrastable laser diode driver applications. The WLD3343 maintains precision laser diode current (constant current mode) or stable photodiode current (constant power mode) using electronics compatible with any laser diode type. Supply up to 2.2 Amps of current to your laser diode from a single +5 to +12 Volt power supply.

FEATURES:
• Small Package (1.30§ x 1.26§ x 0.313§)
• Slow Start Laser Diode Protection
• Optimize for Low and High Power Laser Diodes
• Drive Up to 2.2 Amps Output Current
• Constant Current or Constant Power Operation
• Operates with Any Type of Laser Diode
• Voltage Controlled Setpoint
• TTL Compatible Shutdown Pin
• Adjustable Current Limit
• 2 MHz Constant Current Bandwidth
• Over Temperature Shutdown
Figure 1
Top View Pin Layout and Descriptions


ABSOLUTE MAXIMUM RATINGS SYMBOL  VALUE UNIT
Supply Voltage (Voltage on Pin 14) VDD +4.5 to +12.5 Volts DC
Output Current      (Refer to Datasheet SOA Chart)  IOUT 2.2 Amps
Operating Temperature, case TOPR -40 to +85 ∼C
Storage Temperature TSTG -65 to +150 ∼C
Power Dissipation TAMBIENT = + 25 ∼C PMAX  9 Watts
Weight WLD Chip 0.576 Ounces
﹛ Heatsink 0.512 ﹛
﹛ Fan 0.288 ﹛
PARAMETER  TEST CONDITIONS MIN TYP MAX UNIT
Current Stability, 24 Hour  TAMBIENT = 25∼C 50 ﹛ 75 ppm
Power Stability, 24 Hour TAMBIENT = 25∼C 0.02 ﹛ 0.05 %
Constant Current Bandwidth Sine or Square Wave ﹛ 2 ﹛ MHz
Rise Time ILD = 2.0 Amps ﹛ 160 ﹛ nsec
Fall Time ILD = 2.0 Amps ﹛ 320  ﹛ nsec
Output Current Requires Heatsink and Fan 1.8 2.0 2.2 Amps
Compliance Voltage  Full. Temp Range, IOUT = 2.0 Amps |VDD 每2| ﹛ ﹛ Volts
Supply Voltage, VDD ﹛ 4.5 ﹛ 12 Volts
    

PIN DESCRIPTIONS
﹛
PIN # PIN FUNCTION
1 SHD Shutdown Laser Diode Output Current 每 Float or Zero Volts = Enable ; Greater than +3 Volts = Disable
2 VSET Voltage Setpoint 每 Apply a voltage between pin 2 to pin 7 to adjust setpoint or input a modulation signal
3 IMON Laser Diode Current Monitor 每 Monitor a voltage that is proportional to the laser diode forward current
4 PMON Photodiode Current Monitor 每 Monitor a voltage that is proportional to the monitor photodiode current
5 MODE Mode Configuration 每 Place a 1k次 resistor from pin 5 to pin 6 for Constant Current Mode or a 0.1米F capacitor from pin 5 to pin 6 for Constant Power Mode
6 LIM  Laser Diode Current Limit 每 Place a resistor from pin 6 to pin 7 to limit the laser diode current
7 GND Ground 每 Wire ground connections to pin 7 separately
8 RS+ Positive Laser Diode Current Sense 每 Connect to the positive side of the laser diode current sense resistor
9 OUTB Output B 每 Connect separately to the positive side of the laser diode current sense resistor
10 RS-  Negative Laser Diode Current Sense 每 Connect to the negative side of the laser diode current sense resistor
11 OUTA Output A 每 Type A/B Laser Diode = Connect to Laser Diode Cathode; Type C Laser Diode = Connect to VDD
12 PD+ Positive Photodiode Current Sense 每 Connect to the positive side of the photodiode current sense resistor
13 PD- Negative Photodiode Current Sense 每 Connect to the negative side of the photodiode current sense resistor
14 VDD Power Supply Input 每 Connect +5V to +12V

MECHANICAL SPECIFICATIONS


Material Information PCB FOOTPRINT
PIN DIAMETER: 0.028§
PIN LENGTH: 0.126§
PIN MATERIAL: Nickel Plated Steel
HEAT SPREADER: Nickel Plated Aluminum
PLASTIC COVER: LCP Plastic
ISOLATION: 1200 VDC any pin to case
THERMAL WASHER: WTW002
HEATSINK: WHS302
FANS: WXC303 (+5VDC)
or WXC304 (+12VDC)

TYPICAL PERFORMANCE GRAPHS
Caution:
Do not exceed the Safe Operating Area (SOA). Exceeding the SOA voids the warranty.
To determine if the operating parameters fall within the SOA of the device, the maximum voltage drop across the driver and the maximum current must be plotted on the SOA curves.
These values are used for the example SOA determination. These values are determined from the specifications of the laser diode:
Vs= 12 volts
Vload = 5 volts
ILoad = 1 amp

Follow these steps:

1. Determine the maximum voltage drop across the driver, Vs-Vload (12 volts 每5volts = 7 volts), and mark on the X axis. Mark a vertical line. (line A)
2. Determine the maximum current, Iload, through the driver and mark on the Y axis (1 amp). Mark a horizontal line(line B).
3. Mark Vs on the X axis (point C).
4. From the intersection of line A and line B (BB), draw a straight line to point C. This is the LOAD LINE.

Refer to the chart shown below and note that the LOAD LINE is in the Unsafe Operating Areas for use with no heat sink., or the heat sink alone, but is outside of the Unsafe Operating Area for use with heat sink and fan.

The safe operating area is based on 25ºC Ambient and 75ºC Case temperature.

CONNECTION DIAGRAMS


TYPE A/B LASER DIODE -- CONSTANT CURRENT OPERATION


TYPE A/B LASER DIODE -- CONSTANT POWER OPERATION




HELPFUL HINTS FOR CHOOSING

RSENSE

•Never use a carbon film resistor for RSENSE.
•Avoid resistors with high parasitic inductance.
•Select a resistor with a low temperature coefficient (ppm/∼C).
•Place RSENSE as close to Pins 8 (RS+) and 10 (RS-) on the WLD3343 as possible to avoid parasitic resistance effects from the PCB layout.
•Use Equation 2 for determining the power rating of RSENSE.
Note: Wavelength Electronics recommends a
conservative power rating of 2 times normal maximum for RSENSE.

HELPFUL HINTS FOR CHOOSING RPD
•Never use a carbon film resistor for RPD.
•Select a resistor with a low temperature coefficient (ppm/∼C).
•Place RPD as close to Pins 12 (PD+) and 13 (PD-) on the WLD3343 as possible to avoid parasitic resistance effects from the PCB layout when in constant power mode.


Reducing Noise


The WLD3343 case is isolated from ground. By grounding the case, the signal to noise ratio can be maximized.
If the fan is used to dissipate the heat produced by the WLD3343, the power supplies can be separated to eliminate the noise produced by the fan.
When operating the WLD3343 with a fan, use a separate power supply for the fan. This will help eliminate the noise produced by the fan.
Choose a power supply with the lowest ripple for its rated current.

Wavelength Technology Singapore Pte. Ltd.
BLK 2, Bukit Batok St.24, #06-03/06-09, Skytech Building, Singapore 659480
Tel: 65-65649624 Fax: 65-65643862 Email: info@wavelength-tech.com Website: www.wavelength-tech.com