Datasheet

Loop Characterization Setup
2-3
Test Setup and Results
2.2 Loop Characterization Setup
The TPS54310 EVM contains a 49.9 Ω resistor (R7) in the feedback path for
use in measuring the loop response. Test points on either side of R7 (TP5 and
TP7) provide connection points for network analyzer signals. By injecting a
small ac signal across R7, the loop gain and phase can be measured from one
side of R7 to the other. Because the value of R7 is small in relation to the value
of R5, it does not significantly affect the output voltage set point of the
regulator.
2.3 Efficiency
The TPS54310 EVM efficiency peaks at around 1 A of load current. At full load
this drops to around 90.5%. Figure 2–2 shows the typical efficiency for a 5-V
input and an ambient temperature of 25
°
C. The efficiency is lower at higher
ambient temperatures due to temperature variation in the drain-to-source
resistance of the MOSFETs. The efficiency is also slightly higher at lower
switching frequencies due to the gate and switching losses in the MOSFETs.
The total board losses are shown in Figure 2–3.
Figure 2–2. Measured Efficiency
I
L
– Load Current – A
80
82
84
86
88
90
92
94
96
0 0.5 1 1.5 2 2.5 3
Efficency – %
T
A
= 25°C
V
I
= 5 V