Output Response Speed of System DC Power Supplies
Many devices use multiple different DC bias voltages for testing to ensure correct performance within the specified operating range. Changing multiple bias voltages may require an additional few seconds, which accounts for a significant portion of the testing time.
When changing the output voltage value of the power supply to a new value, multiple steps will occur, as shown in Figure 1. These steps all require a time limit.
Once the power supply receives a command, it must process it, that is, the command processing time. Then the power output reacts and becomes a new setting. The time taken to reach the final value of * within a certain set frequency band is the output response time.
The differences between DC power sources in various systems may be very significant. Table 1 compares the representative command processing and output response time of traditional system DC power supplies with the time of throughput optimized DC power supplies (in this case, Agilent N6750A series DC power supply modules). It belongs to the N6700 modular power system series, as shown in Figure 2. Fast output response can reduce the time required for new voltage settings by several hundred milliseconds
The voltage reduction programmer affects the output response time
Quickly changing the voltage in both directions is crucial for high-throughput testing, so attention should be paid to the step-down programming of the output response time. Many power supplies rely on the actual load of the DUT to reduce voltage. In light load situations, without a voltage regulator programmer, it may take one second for some power supplies to reach their final value. The power supply optimized for high throughput uses an internal buck programmer. The step-down programmer is a load circuit that quickly discharges the power supply and DUT capacitor to achieve fast step-down programming, regardless of the DUT load.
The impact of response speed on test throughput: The automotive ECU instance tests the automotive electronic control unit (ECU) on many voltages, as shown in Figure 3. Assuming the use of a fast response power supply can reduce the output response time by 200 milliseconds. For an ECU with a voltage change of 15 V during a 20 second test, it can reduce the test time by 3 seconds or improve throughput by 15%. There is a clear willingness and welcome for this improvement in the automotive electronics industry.
