13: LPT library function reference Model 4200A-SCS Parameter Analyzer Reference Man
13-142 4200A-901-01 Rev. C / February 2017
pulse_fall
This command sets the fall transition time for the pulse output.
Usage
int pulse_fall(int instr_id, long chan, double fallt);
The instrument identification code of the pulse card, such as VPU1 or VPU2
Channel number of the pulse card:
or
Pulse fall time in seconds (floating point number):
• Fast speed: 10e-9 to 33e-3
• Slow speed: 4220-PGU and 4225-PMU: 50e-9 to 33e-3
•
Pulse modes
Standard
Details
Rise and fall transition time can be set independently for each pulse card channel. There is a
minimum slew rate for both the rise and fall transitions. For the fast speed range, the minimum is
362 µV/µs, or 1 V/2.7 ms. For the high voltage range, the minimum slew rate is 1.8 mV/µs, or
1 V/500 µs. The pulse_range command is used to set pulse speed.
As shown below, the pulse fall time occurs between the 100 percent and 0 percent amplitude points
on the falling edge of the pulse, where the amplitude is the difference between the V High and V Low
pulse values.
The pulse fall time setting takes effect immediately during continuous pulse output. Otherwise, the fall
time setting takes effect when the next trigger is initiated. The pulse_trig command is used to
trigger continuous or burst output.
For slow speed, note that the minimum transition time for pulse source only (no measurement) on the
40 V range is 50 ns for the 4225-PMU and 4220-PGU.
Use the pulse_source_timing command to set the pulse fall time for the 4220-PGU and 4225-
PMU.
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