Each channel can programmatically be set to PMU (parametric measurement unit) mode. As shown in the figure below, when in PMU mode each channel can be configured to operate in Force Current mode or Force Voltage mode.
PMU Operation
When in PMU force current mode each channel’s output current range can be programmatically set to one of the following ranges:
● 32mA to +32mA.
● -8mA to +8mA.
● -2mA to +2mA.
● -512uA to +512uA.
● -128uA to +128uA.
● -32uA to +32uA.
● -8uA to +8uA.
● -2uA to +2uA.
The Force Current PMU mode has a set of programmable commutating high and low voltages that limit the voltage swing when the PMU is forcing current. These commutating voltage values protect the DUT when current is being forced into a high impedance node at the DUT.
If the sensed voltage at the output pin exceeds the high or low commutating voltage, the PMU reduces the output current in order for the output voltage to not exceed the commutating voltage. If the voltage subsequently returns to a level within the commutating voltage thresholds, the PMU resumes forcing the programmed current.
The channel’s PMU force current commutating voltage can be read back and set dynamically at any time even while the DIO is in running mode.
When operating in force voltage mode, the PMU will supply a programmed voltage between -2V and +7 V. The PMU can then measure the current supplied to the DUT. Current measurement ranges are:
● 32mA to +32mA.
● -8mA to +8mA.
● -2mA to +2mA.
● -512uA to +512uA.
● -128uA to +128uA.
● -32uA to +32uA.
● -8uA to +8uA.
● -2uA to +2uA.
If the sensed voltage exceeds the high or low commutating voltage the PMU reduces the output current in order for the output voltage to not exceed the clamp. If the voltage subsequently returns back to within the clamp thresholds, the PMU resumes forcing the programmed current.
Note: When a channel is set to PMU mode it is working in a static mode and does not have any connection to the DIO’s output memory.