Datasheet
( )
( )
( ) ( )
R2OFF
2
OFF
R1OFF R2OFF
1
1
OFF 1
2
1.18
I
R
V 1.18
I I 2.8u 700n
R
R
V 1.18 R 2.8u 700n 1.18
R
=
-
= - + =
= - + +
( )
( ) ( )
R2ON
2
ON
R1ON R2 ON
1
1
ON 1
2
1.30
I
R
V 1.30
I I 700n
R
R
V 1.30 R 700n 1.30
R
=
-
= - =
= - +
Test Setup and Results
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1.3.3 Adjustable UVLO
The under voltage lock out (UVLO) can be adjusted externally using R1 and R2. The EVM is set for a start
voltage of 2.88 V and a stop voltage of 2.57 V using R1 = 47.5 kΩ and R2 = 35.7 kΩ. The following
parameters should be used to determine the UVLO performance:
# Parameter Value
1 Enable Pin Current when OFF 700 nA
2 Enable Pin Current when ON 2.8 µA + 700 nA
3 Enable Pin Turn ON Threshold 1.3 V
4 Enable Pin Turn OFF 1.18 V
Threshold
Use Equation 3 and Equation 4 to calculate required resistor values for different start and stop voltages.
(3)
(4)
2 Test Setup and Results
This section describes how to properly connect, set up, and use the EVM. The section also includes test
results typical for the EVM and covers efficiency, output voltage regulation, load transients, loop response,
output ripple, input ripple, and start-up.
2.1 Input/Output Connections
The EVM is provided with input/output connectors and test points as shown in Table 4 and Figure 1. A
power supply capable of supplying 3 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 must be at
least 6 A to use the full capability of this EVM. 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.
4
TPS54678EVM-155 6-A, SWIFT™ Regulator Evaluation Module SLVU747–June 2012
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