Datasheet

O
R1
V = 0.765 1+
R2
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O O
R1
V = (0.763 + 0.0017 V ) 1+
R2
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www.ti.com Test Setup and Results
1.3 Modifications
These evaluation modules are designed to provide access to the feature of the TPS54426. Some
modification can be made to this module.
1.3.1 Output Voltage Set Point
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 0.765V. The value of R1 for a specific output voltage
can be calculated using Equation 1 and Equation 2.
For output voltage from 0.76V to 2.5V:
(1)
For output voltage over 2.5V:
(2)
Table 3 lists the R1 value for some common output voltages. For higher output voltages of 1.8 V or above,
a feed forward capacitor (C2) may be required to improve phase margin, and is recommended for auto
skip Eco-mode™ stability. 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
2 Test Setup and Results
This section describes how to properly connect, set up, and use the TPS54426EVM-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.
2.1 Input / Output Connections
The TPS54426EVM-608 is provided with input/output connectors and test points as shown in Table 4. A
power supply capable of supplying 2 A must be connected to J1 through a pair of 20 AWG wires. The load
must be connected to J2 through a pair of 20 AWG wires. The maximum load current capability is 4 A.
Wire lengths must be minimized to reduce losses in the wires. Test point TP1 provides a place to monitor
the V
IN
input voltages with TP2 providing a convenient ground reference. TP8 is used to monitor the output
voltage with TP9 as the ground reference.
3
SLVU381–August 2010 TPS54426EVM-608 4-A, SWIFT™ Regulator Evaluation Module
Copyright © 2010, Texas Instruments Incorporated