Keithley 6487 Reference Manual

Model 6487 Reference Manual Applications Guide G-15
Down-range voltage transients are smaller
With the exception of the change from the 2mA range to the 200μA range, the down-range
voltage transient is significantly smaller than the up-range transients. Figure G-12 shows
the voltage presented at the input, measured during a change from 20μA to 2μA with a
2μA input current. The vast difference from the previous figures in voltage scale and time
scale should be noted. Note also that the current limiting resistor will be that of the 2μA
range, 100 times greater than upranging across the same boundary. The voltage transient
of the 2mA to 200μA change with a 200μA input signal is similar to the up-range
response, with the exception that the current limiting R will be 100 times greater in the
case of down-ranging.
Figure G-12
Down-range voltage transients

Keithley 6487 Specifications

General

Type	Picoammeter/Voltage Source
Current Measurement Range	20 fA to 20 mA
Interfaces	GPIB, RS-232
Voltage Burden	< 200 µV
Input Impedance	>10^14 Ω
Power	100 V / 120 V / 220 V / 240 V
Basic Current Measurement Accuracy	0.4%