SLUUBE0A November 2015 – August 2021 TPS549A20
5.1 Test Equipment
- OscilloscopeA digital or analog oscilloscope measures the output ripple. The oscilloscope must be set for the following: 1-MΩ impedance, 20-MHz bandwidth, AC coupling, 1-µs / division horizontal resolution, 20-mV / division vertical resolution. Test points TP7 and TP9 measure the output ripple voltage by placing the oscilloscope probe tip through TP7 and holding the ground barrel on TP9 as shown in Figure 5-1. Using a leaded ground connection can induce additional noise due to the large ground loop.
- Voltage SourceThe input voltage source VIN must be a 0 to 14-V variable-DC source capable of supplying 10 ADC. Connect VIN to J1 as shown in Figure 5-2.
- MultimetersV1: VIN at TP1 (VIN) and TP4 (GND).
V2: VOUT at TP7 (VOUT) and TP9 (GND).
- Output LoadThe output load must an electronic constant-resistance-mode load capable of 0 to 15 ADC at 1.2 V.
Figure 5-1 Tip and Barrel Measurement for VOUT RippleRecommended Wire Gauge:
- VIN to J1 (12-V input)
- The recommended wire size is 1× AWG number 14 per input connection, with the total length of wire less than 4 feet (2 feet input, 2 feet return).
- J3 to LOAD
- The minimum recommended wire size is 2× AWG number 14, with the total length of wire less than 4 feet (2 feet output, 2 feet return).