DC Voltage Current Source/Monitor
The 6240B is a SMU equipped with a high-speed response pulse source and measurement function and a low-resistance measurement function. It has 4½-digit display for voltage and current source and 5½-digit display for measurement, and features high accuracy of ±0.02 %. There are four types of sweep modes available: liner, fixed, random and 2-slope linear sweep, and also pulse measurement with a minimum pulse width of 50 µs is available. Thus, this model can be widely used as evaluation power supply for developing semiconductors and other electronic components and as power supply of characteristic test systems used in production lines.
Moreover, the 6240B is capable of high-precision contact resistance measurement that cancels thermal EMF generated on metal contact surfaces.
Voltage/current source and voltage/current/resistance measurement can be selected by specifying the source and measurement functions.
There are four source modes; DC, pulse, DC sweep, pulse sweep. Then, the sweep modes are classified into four sweep types: fixed sweep, linear sweep, random sweep (arbitrary waveform generation by user programming), 2-slope linear sweep (linear sweep with step value switching).
The minimum pulse width is 50 μs. The minimum cycle is 2 ms, or 500 μs without measurement.
In voltage or current source, the HI/LO limiter settings are very important. The 6240B allows separate setting of HI and LO limiters. Furthermore, for the voltage-limiter, both HI and LO limiters can be set homo-polar. This prevents a capacitor or a battery from being over-discharged. Also, it is suitable for evaluating devices that are used at a constant current and do not tolerate reverse voltage application.
The 6240B can select from three output OFF statuses; STBY (output relay OFF), HiZ (output relay ON and high resistance), and LoZ (output relay ON and low resistance). Using this function can omit unnecessary relay ON/OFF operations.
Consequently it prevents throughput reduction due to relay operating time, extends relay lifetime and increases product reliability.
In addition, the setting of a suspend voltage (voltage in HiZ and LoZ status) can prevent transient current from being generated when connecting voltage sourcing devices such as batteries.
When a conventional generator or electronic load is connected with a battery, the output voltage is 0 V, and then the setting current starts flowing. In this case, the moment that it is connected, transient current sink occurs, causing unnecessary battery discharge. On the other hand, by setting the suspend voltage, the 6240B is connected in highimpedance state at the specified voltage and then the setting current flows. This prevents unnecessary discharge at the connection to the battery.
Comparison of transient current at output ON
The left figure shows the comparison of transient current when the output status is set to Operate with IS=500 mA, VL=±3 V, Vbatt=1.5 V and load resistance = 1 Ω. When setting Vsus = 0 V, transient current of 1.3 A flows at 1.3 V. When setting to Vsus = 1.5 V, it becomes almost 0 A.
The following shows a representative response waveform and output noise. The response between 0 V and 10 V is approximately 30 µs at 0 to 90 % rising time and the output noise is approximately 2.4 mV p-p from DC to 20 MHz.
The 6240B achieves low-resistance measurement without being affected by self-heating of DUTs by using pulse current application, bringing more precise measured values with little errors.
If 0.5 Ω resistance is measured with DC current and pulse current
Source current: 1 A, pulse width: 25 ms, duty factor: 10 % In DC measurement, the measured values fluctuate due to self-heating of the resistor. In pulse measurement, the measured values are not affected by the self-heating