Datasheet

VO = 0.765 1+

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VO = (0.763 + 0.0017 VO) 1+

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Modifications

3 Modifications

These evaluation modules are designed to provide access to the features of the TPS54425. Some

modifications can be made to this module.

3.1 Output Voltage Setpoint

To change the output voltage of the EVMs, it is necessary to change the value of resistor R1. Changing

the value of R1 can change the output voltage above 0.765 V. The value of R1 for a specific output

voltage can be calculated using Equation 1 and Equation 2.

For output voltage from 0.76 V to 2.5 V:

(1)

For output voltage over 2.5 V:

(2)

Table 3 lists the R1 values for some common output voltages. For higher output voltages of 1.8 V or

above, a feedforward capacitor (C2) may be required to improve phase margin. Pads for this component

(C2) are provided on the printed-circuit board. Note that the values given in Table 3 are standard values

and not the exact value calculated using Table 3.

Table 3. Output Voltages

Output Voltage R1 R2 C2 L1

(V) (kΩ) (kΩ) (pF) (µH)

1.0 6.81 22.1 1.5

1.05 8.25 22.1 1.5

1.2 12.7 22.1 1.5

1.8 30.1 22.1 10 -22 2.2

2.5 49.9 22.1 10 -22 2.2

3.3 73.2 22.1 10 -22 2.2

5.0 121 22.1 10 -22 3.3

4 Test Setup and Results

This section describes how to properly connect, set up, and use the TPS54425EVM-608. The section also

includes test results typical for the evaluation modules and efficiency, output load regulation, output line

regulation, load transient response, output voltage ripple, input voltage ripple, start-up, and switching

frequency.

SLVU382–August 2010 TPS54425EVM-608 4-A, SWIFT™ Regulator Evaluation Module