Keithley 2520, Service Manual, Page: 58 / 137

2-28 Calibration Model 2520 Pulsed Laser Diode Test System Service Manual
16. Repeat steps 5 through 14 to calibrate the slow transition pulse.
17. Repeat steps 3 through 16 for the 5A range with the following exceptions:
• Use the 1.2 to 1.6
Ω
resistor.
• Select the 5A source range with this command:
:SOUR1:CURR:RANG 5
• Set the appropriate 10% (0.5) and 90% (4.5) of range values using this
command:
:SOUR1:CURR <Current>
18. Send this command to turn off the output:
:OUTP1 OFF
Step 4: Pulse low calibration
Follow these steps to calibrate current source pulse low. Table 2-11 summarizes
calibration resistances and commands.
1. Connect the 100
Ω
resistor and DMM to the Model 2520 testhead CURRENT
OUTPUT jacks, as shown in Figure 2-4 .
2. Select the DMM DC volts function, and enable auto-range.
3. Put the unit into the pulse mode:
:SOUR1:FUNC:SHAP PULS
4. Send this command to turn on the source output:
:OUTP1 ON
5. Enable fast transition pulses:
:SOUR1:PULS:TRAN:STAT OFF
6. Send the following command to select the 500mA current range:
:SOUR1:CURR:RANG 0.5
7. Send this command to set the current to 15mA:
:SOUR1:CURR:LOW 15e-3
8. Note the DMM reading, then calculate the current from the voltage and actual
resistance, adding a slight offset value: I = V/R + 90
μ
A.
9. Send the calculated current value as the parameter for the following command:
:CAL:PROT:SOUR1:LOW <Calculated_current>
For example, if the current is 14.5mA, the correct command is:
:CAL:PROT:SOUR1:LOW 14.59e-3
10. Send this command to set the current to 1.5mA:
:SOUR1:CURR:LOW 1.5e-3
11. Note the DMM reading, then calculate the current from the voltage and actual
resistance, subtracting a slight offset value: I = V/R -75
μ
A.
12. Send the calculated current value as the parameter for the following command:
:CAL:PROT:SOUR1:LOW <Calculated_current>