Datasheet

OUT1 OUT2

R1 R3

V = 0.765 V 1+ ; V = 0.765 V 1+

R2 R4

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Modifications

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3 Modifications

This evaluation module is designed to provide access to the features of the TPS542951. Some

modifications can be made to this module.

3.1 Output Voltage Setpoint

To change the output voltages of the EVM, it is necessary to change the value of the top resistor of the

feedback divider, R1 or R3. Please refer to the top assembly in Figure 20 to locate the resistors close to

the output connectors. Changing the value of R1 or R3 can change the output voltage above 0.765 V. The

value of R1 or R3 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 or R3 values for some common output voltages. For output voltages of 1.8 V or

above, a feedforward capacitor (C21 or C20) may be required to improve the phase margin. Pads for this

component (C21 or C20) are provided on the printed-circuit board. Note that the resistor values given in

Table 3 are standard values and not the exact values calculated using Equation 1.

Table 3. Output Voltages

C14, C15, C18 Total Capacitance,

Output Voltage R1, R3 R2, R4 C21, C20 L1, L2

C16, C17, C19 Total Capacitance

(V) (kΩ) (kΩ) (pF) (µH)

(µF)

1 6.81 22.1 1.5 - 2.2 22 - 68

1.05 8.25 22.1 1.5 - 2.2 22 - 68

1.2 12.7 22.1 1.5 - 2.2 22 - 68

1.5 21.5 22.1 1.5 - 2.2 22 - 68

1.8 30.1 22.1 5 - 22 2.2 - 3.3 22 - 68

2.5 49.9 22.1 5 - 22 2.2 - 3.3 22 - 68

3.3 73.2 22.1 5 - 22 2.2 - 3.3 22 - 68

5 124 22.1 5 - 22 4.7 22 - 68

6.5 165 22.1 5 - 22 4.7 22 - 68

3.2 Output Filter and Closed-Loop Response

The TPS542951 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. R11

and R12 are provided for convenience in breaking the control loop and measuring the closed-loop

response.

TPS542951 Dual Channel SWIFT™ Evaluation Module SLVU767–August 2012

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