In this short presentation we'll introduce the PCM-7140 including a product overview, what's in the box, how to set up the PCM-7140 Laser Diode Driver Module and solutions to some common problems.
https://directedenergy.com/product/pcm-7140-1/
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https://directedenergy.com/product/pcm-7140-200/
The PCM-7140 is a series of compact pulsed current sources designed to drive laser diodes, bars, arrays, or any low impedance load. The key specifications are output current from .1 A to 200 A, rise and fall times below 1 μs, pulse widths from 1 μs to 13 ms, pulse repetition rates from single shot to 100 kHz, and forward voltage from 0 V to 60 V.
The PCM-7140 output current may be set with an internal potentiometer or an external analog voltage. The pulse width is controlled with an external trigger source.
The system requires two DC supplies for operation: 12 V for housekeeping and a voltage ≤ 20 V above the laser diode’s forward voltage.
The laser or load is connected to the PCM-7140 with a 100 cm length of 18 AWG twisted pair cable (included). This same cable has the DC input connection from the high voltage power supply.
The PCM-7140 module is liquid cooled with a liquid temperature of 11 °C to 22 °C with a flow rate of 6 liters per minute. The connection type is 3/8” tubing.
Features
Pulsed Current Monitor Output
Liquid cooling for high average power applications
Applications
The PCM-7140 is designed to drive laser diodes, bars, arrays, or any low-impedance load with a forward voltage drop up to 60 V for laboratory, research and industrial application.
4. Available Models
PCM-7140-200
Output Current 5A to 200A
Rise/Fall Time less than 20 µs
PCM-7140-10
Output Current 1A to 10A
Rise/Fall Time less than 12 µs
PCM-7140-1
Output Current 0.1A to 1A
Rise/Fall Time less than 5 µs
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5. Technical Overview 5
Current Monitor
Potentiometer / Analog control of output current
Error detection
Open load
Over temperature
Liquid Cooled
Flow rate 1L/min to 6 L/min
Input Temperature 11 °C to 22 °C
Connection 3/8” tubing
9. Technical Overview (200A unit) 9
Current rise/fall time
≤ 20 µs : 5 A to 49 A
≤ 16 µs : 50 A to 99 A
≤ 10 µs : ≥ 100 A
Forward Voltage
0V to 55V
Frequency Range
Single shot to 5,500 Hz
100% Duty Cycle Operation
5A to 20A 200 A, 12.5 V, 200 µs pulse width
13. Technical Overview (10A unit) 13
Current rise/fall time
≤ 12 µs : 1 A to 3 A
≤ 3 µs : 3.01 A to 5 A
≤ 2 µs : ≥ 5.01 A
Forward Voltage
0V to 65V
Frequency Range
Single shot to 120,000 Hz
100% Duty Cycle Operation
1A to 10A*
10 A, 300 µs pulse width
16. Technical Overview (1A unit) 16
Current rise/fall time
≤ 5 µs : 0.1 A to 0.499 A
≤ 2 µs : 0.500 A to 1.0 A
Forward Voltage
0V to 65V
Frequency Range
Single Shot to 100,000 Hz
100% Duty Cycle Operation
0.1 A to 1 A
1000 mA, 300 µs pulse width
21. Setting Up 21
These parts will not be used, set them aside.
We will be using a different cable for this presentation.
We also will not install the four rubber feet.
22. Setting Up 22
Install the input/output cable.
Install the control cable to the PCM-7140 and manual control board.
23. Setting Up 23
Install the load to the input / output cable.
This is a 0.1964 ohm low inductance high power load
25. Setting Up 25
Install SMB/BNC cable (not included) from the trigger source to J12 on manual
control board.
26. Setting Up 26
Connect hoses to the copper pipes. And connect them to your chiller or house
water. Turn on chiller or water source and assure there are no leaks.
27. Setting Up 27
Install SMB/BNC cable (not included) from the current monitor to oscilloscope.
28. Setting Up 28
Change dipswitch settings on manual control board as shown.
This will enable current control using R40 on the manual control board.
Adjust R40 to midscale, this will set the output current to about 100A.
30. Setting Up 30
Enable the 12VDC power source.
Note that the Status LED turns on red. Within 10 seconds enable the DC input
supply.
31. Setting Up 31
Enable the DC input supply.
We are going create a 110A pulse so we set the voltage to
(110A)*(0.1964 ohm) + 12V = 34V
32. Setting Up 32
As soon as the system has +12V DC and DC Input Voltage the status LED goes out.
Now the system can be enabled.
33. Setting Up 33
Enable the trigger source.
Make sure that the frequency and pulse width is safe by reviewing the SOA
graphs.
34. Setting Up 34
Here is the output pulse waveform. This is looking at current monitor.
Note the scope is set to 50ohm impedance 1:1.
35. Setting Up 35
Here is a view of the entire system, except the DC input source which is out of the frame.
36. Solutions to Common Problems 36
Problem: Red status LED is ON
Solutions:
1) Upon power up the status LED is on for about 10 seconds. This is normal.
2) Open Load Fault detected?
The DC Input Voltage must be over Vforward by the amount shown in the datasheet. Review the datasheet,
power down 12V and DC input voltage for at least 30 seconds. Power up the module using the procedure
in the manual.
3) Thermal Fault detected?
Check liquid flow. Check SOA curves in the datasheet to determine if the module is running within the
Safe Operating Area. Review the DC Input Voltage setting to assure it is set properly. Power down 12V
and DC input voltage for at least 30 seconds. Power up the module using the procedure in the manual.
37. Solutions to Common Problems
Problem: Ringing or distortion on the output
Solutions:
1) Review datasheet to assure DC input voltage is set properly.
2) Make sure the laser is connected to the load board properly. It is very important to reduce the
inductance as much as possible.
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