Datasheet

0.765 1

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= × +

ç ÷

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OUT

V V

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Modifications

3 Modifications

This evaluation module is designed to provide access to the features of the TPS54427. Some

modifications can be made to this module.

3.1 Output Voltage Setpoint

To change the output voltage of the evaluation module, 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.

For output voltage from 0.76 V to 7 V:

(1)

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

feedforward capacitor (C4) may be required to improve the phase margin. Pads for this component (C4)

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

values and not the exact value calculated using Equation 1.

Table 3. Output Voltages

Output Voltage R1 R2 C4 L1 C9, C10,

(V) (kΩ) (kΩ) (pF) (µH) C11Total

Capacitance

(µF)

1 6.81 22.1 1.5 22 - 68

1.05 8.25 22.1 1.5 22 - 68

1.2 12.7 22.1 1.5 22 - 68

1.5 21.5 22.1 1.5 22 - 68

1.8 30.1 22.1 5 - 22 2.2 22 - 68

2.5 49.9 22.1 5 - 22 2.2 22 - 68

3.3 73.2 22.1 5 - 22 2.2 22 - 68

5 124 22.1 5 - 22 3.3 22 - 68

6.5 165 22.1 5 - 22 3.3 22 - 68

3.2 Output Filter and Closed-Loop Response

The TPS54427 relies on the output filter characteristics to ensure stability of the control loop. The

recommended output filter components for common output voltages are given in Table 3. It may be

possible for other output filter component values to provide acceptable closed-loop characteristics. R3 and

TP4 are provided for convenience in breaking the control loop and measuring the closed-loop response.

SLVU579–December 2011 TPS54427, 4-A, SWIFT™ Regulator— Evaluation Module

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