LDPC Diode Driver
The LDPC series laser diode drivers offer the laser de- signer a compact low cost power supply for a variety of medical and industrial applications. In order to take full advantage of this unique product, care must be taken during the design process to ensure long term reliabilty. This data sheet includes answers to many commonly asked questions about the various configurations avail- able and includes critial cooling and electrical informa- tion.
Specifications
Maximum Output Power:
225 watts
Maximum Output Current:
50 amps
Performance
Current Ripple:
0.2% at maximum output current
Regulation:
0.5% at maximum output current
Current Overshoot:
< 1% of maximum output current
Power Limit:
Limited to Maximum power with Fold Back Circuit
Rise/Fall Time:
3-20µs. depending upon output voltage
Interface
Inhibit/Enable:
5V to 15V to enable output
Current Program:
0 to 10V = 0 to full current
Current Monitor:
0 to 10V = 0 to full current
Voltage Monitor:
0 to 10V = 0 to full voltage1
Protection
Power supply Protection:
Reverse Input voltage, input overvoltage, over temp
Laser Diode Protection:
Control rise/fall times, no overshoot
Dimensions
LDPC:
68.75mm x 150mm x 45mm high
Operating Temp:
0 to 40°C, 90% RH non condensing
Cooling2:
See page 3 for fan size and mounting instructions
1. If maximum compliance voltage is less than 10V, Vout Monitor will read output voltage directly. If maximum compliance voltage is greater than 10V, then Vout Monitor will be scaled such that 0-10V = 0-Voutmax.
2. Proper cooling is required for reliable operation. See page 3 for correct fan placement and other cooling recommentations.
Maximum Output Ratings
The LDPC laser diode drivers are available in two power levels. Mod- els to ~ 100watts (50amps) can be operated from 12 or 15 volts while power levels up to 225 watts require 24VDC input. The table to the right details typical input voltages and currents when the units are run at maximum output current for their particular power rating. The LDPC power supplies can be ordered with any output voltage and current as long as you do not exceed the maxi- mum parameters listed.
OutputV @ Max current
Output Power
Input Current
Efficiency
24VDC input
2V @ 50A
100 watts
7.0A
60%
4V @ 40A
160 watts
9.0A
74%
6V @ 37A
225 watts
11.8A
79%
10V @ 22.5A
225 watts
11.7A
85%
16V @ 14A
225 watts
10.4A
90%
12VDC/15VDC input
2.38V @ 50A
119 watts
11.6A/15Vin
72%
2.38V @ 50A
119 watts
14.9A/12Vin
72%
Part Number Example: LDPC-10-6-12 = 10amps, 6 volts output, 12VDC input
Interface Description
The LDPC interface is a simplified version of the LDD series controls utilizing the same analog 10 volt programming. The connector is a 6 pin right angle board mounted Molex #22-05-3061. Their are several options for the mating connector (not included) but a suitable part number is the 22-01-2067. Note Vmon. (pin2) scale for various output voltages.
Pin
Function
Description
Impedance
1
Enable
5 to 15V=Enable Output, Default OFF
10K
2
V monitor
1 to 1 for Vout ≤ 10V
0 to 10V = 0 to full scale for V > 10V
1K
3
Pulse
TTL High = ON, Default = High
10K
4
I prog
0 to 10V = 0 to Full scale
10K
5
GND
N/A
6
I mon
0 to 10V = 0 to Full Scale
1K
Connectors
1. Input Connector: .25” male Quick Connects.
Note: Input current cannot exceed 15 amps.
2. Interface Connector: Molex # 22-05-3061.
3. Fan Output: J1 (Molex # 26-60-4020 ) output is
equal to the input voltage for 12 or 24 volts input.
For 15 VDC input J1 = 12 V.
4.Output Connectors: 6 x 32 Screws. See outline
drawing below for location.
Cooling Requirements
Recommended Fan: ≥30cfm, 60mm x 60mm fan
Note: Larger dimentional fans of equal output will not concentrate the airflow to adaquately cool this product.
Proper cooling of the LDPC board is critical to the operation and reliability of the product. The diagram above shows the fan position and required airflow for safe operation. The fan must be positioned as shown in diagram above. Mount fan .25” from board for proper cooling. Note: Failure to properly cool the board using the correct size and position of the fans may result in thermal shutdown and potential catastrophic damage to the power supply. Damage to the board from inadequate cooling is not covered under warranty.
Pulsed Operation
The LDPC supplies are primarily designed for CW operation but have a very short rise/fall time and are easily pulsed using pulse pin (#3) on the interface connector. Figure is a scope trace of a 50 amp 2 volt pulse with a rise/fall time of 2.2µs. The chart below shows typical compliance voltage/rise time values.
Compliance voltage
Rise/fall time
2 volts
3µs.
4 volts
5µs.
6 volts
7µs.
8 volts
10µs.
10 volts
12µs.
12 volts
15µs.
14 volts
17µs.
15 volts
20µs.
Start-up Procedures
If you are using this product for the first time please read and follow the following procedures:
1. Unpack module and position the device on a flat surface with the heat sinks up. The LDPC module will not cool properly when mounted upside down (heatsinks down). Locate proper size fan as outlined on page 3. (Consult customer service for proper vertical mounting and cooling).
2. To protect you laser diode from damage it is recommended that you apply a dummy load to the output of the LDPC module during tests. A standard “fast recovery” diode or series string of these diodes that approximately matches the voltage drop of your laser diode should be used for testing.
3. Connect your current monitoring device to the current monitor output pin 6 on the interface connector. A digital voltage meter set to 0 to 10V for CW operation or a scope for puled operation. Connect a 0 to 10V program voltage to the current program input pin 4. Optional: you can monitor compliance voltage at the voltage monitor output pin 2. Install jumper JPI for pulsed opeation or a TTL pulse source for QCW.
4. Apply DC input voltage, apply a signal to enable pin 1 and adjust current program voltage to desired output current. Moni- tor output current with monitoring device. See interface description , page 2 for input and output voltages.
5. For pulsed operation connect pulse pin 3 to a pulse signal.
Note: Grounding the negative output of the module may cause ground loops and excessive noise.