Why does the 42841A shut down with an error message display on the E4980A/ 4284A when DC bias current exceeds a certain level?
The error number E25 or E26 is displayed when the DC resistance of DUT is too large for the 42841A to force a setup current (bias current) to the DUT at the selected bias current range of the 42841A. Please refer to figure 4-3 in the 42841A operation manual for the relationship between the maximum bias output voltage and current.
The DC resistance of DUT must be lower than the value of V max / I bias (maximum bias output voltage divided by bias current) as follows.
R dc ≤ V max/ I bias
Where,
R dc: DC resistance of DUT
V max: Maximum DC bias output voltage on the selected DC bias current range (1 A, 5 A or 20 A)
I bias: DC bias output current
The V max values for 1 A, 5 A and 20 A ranges are shown in the table below:
| Range (20 A system) | Range (40 A system) | V max value |
|---|---|---|
| 1 A (0.01 to 1.00 A) | 2 A (0.02 to 2.00 A) | 35 V dc |
| 5 A (1.1 to 5.0 A) | 10 A (2.2 to 10.0 A) | 5 V dc |
| 20 A (5.1 A to 20.0A) | 40 A (10.2 A to 40.0A) | 1 V dc |
The following graph shows the relationship between the DC bias current (I bias) and the maximum DC resistance (R dc) of DUT for which the bias current can be controlled at the setup value (I bias).
