Datasheet

Performance Specification Summary
1-4
1.3.3 Output Voltage
The output voltage of the TPS54310 EVM can be adjusted to any value down
to 0.9 V by changing only one component value (R4). The value of R4 for a
specific output voltage can be calculated by using equation 1–1. Table 1–2
lists the value of R4 for some common bus voltages.
R
4
+ 10 kW
0.891 V
V
O
–0.891 V
(1–1)
Table 1–2.Output Voltage Programming
Output Voltage
(V)
R4
(kΩ)
0.9 1000
1.2 28.7
1.5 14.7
1.8 9.76
2.5 5.49
3.3 3.74
1.3.4 Slow Start
The slow start time of the EVM can be modified by changing the value of C1.
Use equation 1–2 to calculate the value of C1 for a specific slow start time. With
C1 open, the slow start time is typically 3.6 ms. The slow start time can not be
made faster than 3.6 ms.
C
1
+
T
SS
5 mA
0.891 V
(1–2)
1.3.5 Improving Transient Response
The feedback compensation components are R2, R4, R5, R6, C4, C5, and C6
(see Figure 4–1), and were selected based on the output of the SWIFT
Designer software tool. This results in a unity gain bandwidth of 30 kHz, and
a phase margin of 95° (see Figure 2–8). The TPS54310 EVM responds to a
3-A load transient within 30 µs using the compensation shown in the
schematic. While this response time is more than sufficient for most
applications, the response time can be made faster by changing the values of
the feedback compensation components. Using the values given by
Table 1–3, the unity gain bandwidth is increased to 75 kHz, and the phase
margin is 72° (see Figure 2–9). With this alternate compensation, the output
voltage remains within a ±2% regulation band during a 3-A load transient (see
Figure 2–7).