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Agilent AN 1246
Pulsed Characterization of Power
Semiconductors Using Electronic Loads
Application Note

Electronic Load Improves Power
Electronic Loads
Semiconductor Measurements
An electronic load eliminates the self- An electronic load (see figure) employs a power MOSFET as an electronically variable load that dis-
heating problems associated with sipates power. The electronic load senses MOSFET current (Iin), then amplifies it, compares it with
measuring the on-state voltage drop a reference, and feeds back the output of an error amplifier to the MOSFET gate. This forms a
and transconductance (or current closed-loop current control system. Therefore, the electronic load's input current (IIN) is propor-
gain) of power semiconductors. tional to the control reference input. Input current, IIN, loads the DC power source (battery or power
On-state voltage drop and transcon-
ductance (or current gain) of power Given a fixed control reference, the load acts as a series current regulator. If the control reference
FETs, BJTs, and IGBTs are tempera- is proportional to the load input voltage (VIN), the load behaves like a high quality power resistor.
Some load manufacturers also offer a constant voltage regulation mode in which the load
ture dependent, but are typically
behaves like a power zener diode.
specified at 25