Datasheet

OUT

R9 = R10 ×( 1)

0.6 V

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Introduction

1.3 Modifications

These evaluation modules are designed to provide access to the features of the TPS54678. This module

can be modified.

1.3.1 Output Voltage Set Point

The voltage dividers, R9 and R10, are used to set the output voltage. Change the output voltage of the

EVM by changing the value of resistor R9. Changing the value of R9 changes the output voltage above

0.6 V. The value of R9 for a specific output voltage is calculated using Equation 1. Use 10.0 kΩ for R10.

(1)

Table 3 lists the R9 and R10 values for some common output voltages. Note that V

must be in a range

so that the minimum on-time is greater than 80 ns, and the maximum duty cycle is less than 92%. The

values given in Table 3 show standard values and the closest E96 match.

Table 3. Output Voltages Available

R9 Ideal R9 Actual (E96) R10 V

OUT

Ideal V

OUT

Actual

0 0 10.0E+3 0.60 0.60

3.33E+3 3.32E+3 10.0E+3 0.80 0.80

6.67E+3 6.65E+3 10.0E+3 1.00 1.00

10.00E+3 10.00E+3 10.0E+3 1.20 1.20

13.33E+3 13.30E+3 10.0E+3 1.40 1.40

16.67E+3 16.50E+3 10.0E+3 1.60 1.59

20.00E+3 20.00E+3 10.0E+3 1.80 1.80

23.33E+3 23.20E+3 10.0E+3 2.00 1.99

26.67E+3 26.70E+3 10.0E+3 2.20 2.20

30.00E+3 30.10E+3 10.0E+3 2.40 2.41

33.33E+3 33.20E+3 10.0E+3 2.60 2.59

36.67E+3 36.50E+3 10.0E+3 2.80 2.79

1.3.2 Slow Start Time

The slow start time is adjusted by changing the value of C7. Use Equation 2 to calculate the required

value of C7 for a desired slow start time

Css(nF) = 3 × Tss (ms) (2)

C7 is set to 0.01 μF on the EVM for a default slow start time of 3.33 ms.

SLVU747–June 2012 TPS54678EVM-155 6-A, SWIFT™ Regulator Evaluation Module

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