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EVM Test Setup
5.1Output Load (LOAD1)
For the output load to VOUT, a programmable electronic load set to constant current mode and capable of
sinking between 0ADC and 30ADC, is used. Using a dc voltmeter, V2, it is also advised to make all output voltage measurements directly at J9 and J10 pins. Unless the load has remote sense capability, measuring VOUT at LOAD1 results in some voltage measurement error, especially at higher load current, due to finite voltage drops across the wires between J8 and the electronic load.
5.2DC Input Source (VIN)
The input voltage is a variable DC source capable of supplying between 0 VDC and 72 VDC at no less than 3.5 ADC, and connected to J1 and A1 as shown in Figure 2. For fault protection to the EVM, good common practice is to limit the source current to no more than 4 ADC for a 36 V input. A dc ammeter, A1 should also be inserted between VIN and J1 as shown in Figure 2.
5.3Network Analyzer
A network analyzer can be connected directly to J6 and J7. The UCC2891EVM provides a
5.4Recommended Wire Guage
The connection between the source voltage, VIN and J1 of the EVM can carry as much as 3.25ADC. The minimum recommended wire size is AWG #20 with the total length of wire less than 8 feet (4 feet input, 4
feet return). The connection between J8 of the EVM and LOAD1 can carry as much as 30ADC. The minimum recommended wire size is AWG #16, with the total length of wire less than 8 feet (4 feet output, 4 feet return).
5.5Fan
Most power converters include components that can be hot to the touch when approaching temperatures of 605C. Because this EVM is not enclosed to allow probing of circuit nodes, a small fan capable of
8 | Using the UCC2891 Active Clamp Current Mode PWM Controller | SLUU178A |
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