Texas Instruments TPS54231 User manual

User’s Guide
TPS54231 Step-Down Converter Evaluation Module User's
Guide
Table of Contents
1 Introduction.............................................................................................................................................................................2
1.1 Background........................................................................................................................................................................ 2
1.2 Performance Specification Summary.................................................................................................................................2
1.3 Modifications...................................................................................................................................................................... 3
2 Test Setup and Results.......................................................................................................................................................... 3
2.1 Input / Output Connections................................................................................................................................................ 3
2.2 Efficiency............................................................................................................................................................................4
2.3 Output Voltage Load Regulation........................................................................................................................................ 5
2.4 Output Voltage Line Regulation......................................................................................................................................... 6
2.5 Load Transients..................................................................................................................................................................6
2.6 Loop Characteristics.......................................................................................................................................................... 7
2.7 Output Voltage Ripple........................................................................................................................................................ 7
2.8 Input Voltage Ripple........................................................................................................................................................... 8
2.9 Powering Up.......................................................................................................................................................................8
2.10 Eco-mode Operation........................................................................................................................................................ 9
2.11 Thermal Characteristics....................................................................................................................................................9
3 Board Layout.........................................................................................................................................................................11
3.1 Layout...............................................................................................................................................................................11
3.2 Estimated Circuit Area..................................................................................................................................................... 12
4 Schematic and Bill of Materials...........................................................................................................................................13
4.1 Schematic........................................................................................................................................................................ 13
4.2 Bill of Materials.................................................................................................................................................................14
5 Revision History................................................................................................................................................................... 15
List of Figures
Figure 2-1. TPS54231EVM-372 Efficiency.................................................................................................................................. 4
Figure 2-2. TPS54231EVM-372 Low Current Efficiency..............................................................................................................5
Figure 2-3. TPS54231EVM-372 Load Regulation....................................................................................................................... 5
Figure 2-4. TPS54231EVM-372 Line Regulation........................................................................................................................ 6
Figure 2-5. TPS54231EVM-372 Transient Response................................................................................................................. 6
Figure 2-6. TPS54231EVM-372 Loop Response........................................................................................................................ 7
Figure 2-7. TPS54231EVM-372 Output Ripple........................................................................................................................... 7
Figure 2-8. TPS54231EVM-372 Input Ripple.............................................................................................................................. 8
Figure 2-9. TPS54231EVM-372 Start-Up Relative to VIN ...........................................................................................................8
Figure 2-10. TPS54231EVM-372 Start-up Relative to Enable.................................................................................................... 9
Figure 2-11. TPS54231EVM–372 Eco–mode Operation.............................................................................................................9
Figure 2-12. TPS54231EVM-372 Thermal Image..................................................................................................................... 10
Figure 3-1. TPS54231EVM-372 Top-Side Layout......................................................................................................................11
Figure 3-2. TPS54231EVM-372 Bottom-Side Layout................................................................................................................12
Figure 3-3. TPS54231EVM-372 Top-Side Assembly.................................................................................................................12
Figure 4-1. TPS54231EVM-372 Schematic...............................................................................................................................14
List of Tables
Table 1-1. Input Voltage and Output Current Summary...............................................................................................................2
Table 1-2. TPS54231EVM-372 Performance Specification Summary.........................................................................................2
Table 1-3. Output Voltages Available...........................................................................................................................................3
Table 2-1. EVM Connectors and Test Points............................................................................................................................... 4
Table 4-1. TPS54231EVM-372 Bill of Materials.........................................................................................................................15
www.ti.com Table of Contents
SLVU263A – AUGUST 2008 – REVISED OCTOBER 2021
Submit Document Feedback
TPS54231 Step-Down Converter Evaluation Module User's Guide 1
Copyright © 2021 Texas Instruments Incorporated

Trademarks
SWIFT™ is a trademark of Texas Instruments.
All trademarks are the property of their respective owners.
1 Introduction
This user's guide contains background information for the TPS54231 as well as support documentation for
the TPS54231EVM-372 evaluation module (HPA372). Also included are the performance specifications, the
schematic, and the bill of materials for the TPS54231EVM-372.
1.1 Background
The TPS54231 dc/dc converter is designed to provide up to a 2 A output from an input voltage source of 3.5
V to 28 V. Rated input voltage and output current range for the evaluation module are given in Table 1-1.
This evaluation module is designed to demonstrate the small printed-circuit-board areas that may be achieved
when designing with the TPS54231 regulator. The switching frequency is internally set at a nominal 570 kHz.
The high-side MOSFET is incorporated inside the TPS54231 package along with the gate drive circuitry. The
low drain-to-source on resistance of the MOSFET allows the TPS54231 to achieve high efficiencies and helps
keep the junction temperature low at high output currents. The compensation components are external to the
integrated circuit (IC), and an external divider allows for an adjustable output voltage. Additionally, the TPS54231
provides adjustable slow start and undervoltage lockout inputs. The absolute maximum input voltage is 30 V for
the TPS54231EVM-372.
Table 1-1. Input Voltage and Output Current Summary
EVM INPUT VOLTAGE RANGE OUTPUT CURRENT RANGE
TPS54231EVM-372 VIN = 7 V to 28 V 0 A to 2 A
1.2 Performance Specification Summary
A summary of the TPS54231EVM-372 performance specifications is provided in Table 1-2. Specifications are
given for an input voltage of VIN = 15 V and an output voltage of 3.3 V, unless otherwise specified. The
TPS54231EVM-372 is designed and tested for VIN = 7 V to 28 V. The ambient temperature is 25°C for all
measurements, unless otherwise noted.
Table 1-2. TPS54231EVM-372 Performance Specification Summary
SPECIFICATION TEST CONDITIONS MIN TYP MAX UNIT
VIN voltage range 7 15 28 V
Output voltage set point 3.3 V
Output current range VIN = 7 V to 28 V 0 2 A
Line regulation IO = 1 A, VIN = 7 V to 28 V ±0.15%
Load regulation VIN = 15 V, IO = 0 A to 2 A ±0.15%
Load transient response IO = 0.5 A to 1.5 A Voltage change –100 mV
Recovery time 150 μs
IO = 1.5 A to 0.5 A Voltage change 100 mV
Recovery time 150 μs
Loop bandwidth VIN = 15 V, IO = 1 A 27 kHz
Phase margin VIN = 15 V , IO = 1 A 55 °
Input ripple voltage IO = 2 A 125 mVpp
Output ripple voltage IO = 2 A 5 mVpp
Output rise time 6 ms
Operating frequency 570 kHz
Maximum efficiency TPS54231EVM-372, VIN = 7 V, IO = 0.5 A 92.7%
Trademarks www.ti.com
2TPS54231 Step-Down Converter Evaluation Module User's Guide SLVU263A – AUGUST 2008 – REVISED OCTOBER 2021
Submit Document Feedback
Copyright © 2021 Texas Instruments Incorporated

1.3 Modifications
These evaluation modules are designed to provide access to the features of the TPS54231. Some modifications
can be made to this module.
1.3.1 Output Voltage Set Point
To change the output voltage of the EVM, it is necessary to change the value of resistor R6. Changing the value
of R6 can change the output voltage above 0.8 V. The value of R6 for a specific output voltage can be calculated
using Equation 1.
6
0.8
10.2
0.8
= W ´
-
OU T
V
R k
V V
(1)
Table 1-3 lists the R6 values for some common output voltages. Note that VIN must be in a range so that the
minimum on-time is greater than 130 ns, and the maximum duty cycle is less than 91%. The values given in
Table 1-3 are standard values, not the exact value calculated using Equation 1.
Table 1-3. Output Voltages Available
Output Voltage
(V)
R6 Value (kΩ)
1.8 8.25
2.5 4.75
3.3 3.24
5 1.96
2 Test Setup and Results
This section describes how to properly connect, set up, and use the TPS54231EVM-372 evaluation module.
The section also includes test results typical for the evaluation module and covers efficiency, output voltage
regulation, load transients, loop response, output ripple, input ripple, and start-up.
2.1 Input / Output Connections
The TPS54231EVM-372 is provided with input/output connectors and test points as shown in Table 2-1. 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 J4 through a pair of 20 AWG wires. The maximum load current capability must be 2 A. Wire
lengths must be minimized to reduce losses in the wires. Test-point TP1 provides a place to monitor the VIN input
voltages with TP2 providing a convenient ground reference. TP5 is used to monitor the output voltage with TP6
as the ground reference.
www.ti.com Introduction
SLVU263A – AUGUST 2008 – REVISED OCTOBER 2021
Submit Document Feedback
TPS54231 Step-Down Converter Evaluation Module User's Guide 3
Copyright © 2021 Texas Instruments Incorporated

Table 2-1. EVM Connectors and Test Points
Reference Designator Function
J1 VIN (see Table 1-1 for VIN range)
J2 2-pin header for enable. Connect EN to ground to disable, open to enable.
J3 2-pin header for slow start monitor and GND.
J4 VOUT, 3.3 V at 2 A maximum
TP1 VIN test point at VIN connector
TP2 GND test point at VIN
TP3 PH test point
TP4 Test point between voltage divider network and output. Used for loop response measurements.
TP5 Output voltage test point at OUT connector
TP6 GND test point at OUT connector
2.2 Efficiency
The efficiency of this EVM peaks at a load current of about 0.5 A - 1 A and then decreases as the load
current increases towards full load. Figure 2-1 shows the efficiency for the TPS54231EVM-372 at an ambient
temperature of 25°C.
0%
10%
20%
30%
40%
50%
60%
70%
80%
90%
100%
0.00 0.25 0.50 0.75 1.00 1.25 1.50 1.75 2.00
Output Current(A) - IO
Efficiency - %
V = 15 V
IN
V = 24 V
IN
V = 28 V
IN
V = 7 V
IN
Figure 2-1. TPS54231EVM-372 Efficiency
Figure 2-2 shows the efficiency for the TPS54231EVM-372 at lower output currents between 0.02 A and 0.20 A
at an ambient temperature of 25°C.
Test Setup and Results www.ti.com
4TPS54231 Step-Down Converter Evaluation Module User's Guide SLVU263A – AUGUST 2008 – REVISED OCTOBER 2021
Submit Document Feedback
Copyright © 2021 Texas Instruments Incorporated

0%
10%
20%
30%
40%
50%
60%
70%
80%
90%
100%
0.00 0.02 0.04 0.06 0.08 0.10 0.12 0.14 0.16 0.18 0.20
Output Current (I ) - A
O
Efficiency - %
V = 15 V
IN
V = 7 V
IN
V = 28 V
IN V = 24 V
IN
Figure 2-2. TPS54231EVM-372 Low Current Efficiency
The efficiency may be lower at higher ambient temperatures, due to temperature variation in the drain-to-source
resistance of the internal MOSFET.
2.3 Output Voltage Load Regulation
The load regulation for the TPS54231EVM-372 is shown in Figure 2-3.
-0.10%
-0.05%
0.00%
0.05%
0.10%
0.15%
0.20%
0.00 0.25 0.50 0.75 1.00 1.25 1.50 1.75 2.00
Output Current (A)
Output Regulation (%)
Output Current (I ) - A
O
Output Regulation - %
V = 7 V
IN
V = 15 V
IN
V = 24 V
IN
V = 28 V
IN
Figure 2-3. TPS54231EVM-372 Load Regulation
Measurements are given for an ambient temperature of 25°C.
www.ti.com Test Setup and Results
SLVU263A – AUGUST 2008 – REVISED OCTOBER 2021
Submit Document Feedback
TPS54231 Step-Down Converter Evaluation Module User's Guide 5
Copyright © 2021 Texas Instruments Incorporated

2.4 Output Voltage Line Regulation
The line regulation for the TPS54231EVM-372 is shown in Figure 2-4.
Input Voltage (V ) - V
IN
Output Regulation - %
I = 0 A
O
-0.10%
-0.05%
0.00%
0.05%
0.10%
0.15%
5.00 10.00 15.00 20.00 25.00 30.00
I = 2 A
O
I = 1 A
O
Figure 2-4. TPS54231EVM-372 Line Regulation
2.5 Load Transients
The TPS54231EVM-372 response to load transients is shown in Figure 2-5. The current step is from 25% to
75% of maximum rated load at 15V input. Total peak-to-peak voltage variation is as shown, including ripple and
noise on the output.
Figure 2-5. TPS54231EVM-372 Transient Response
Test Setup and Results www.ti.com
6TPS54231 Step-Down Converter Evaluation Module User's Guide SLVU263A – AUGUST 2008 – REVISED OCTOBER 2021
Submit Document Feedback
Copyright © 2021 Texas Instruments Incorporated

2.6 Loop Characteristics
The TPS54231EVM-372 loop-response characteristics are shown in Figure 2-6 . Gain and phase plots are
shown for VIN voltage of 15 V. Load current for the measurement is 1 A.
-30
-20
-10
0
10
20
30
40
50
60
10 100 1k 10k 100k 1M
Frequency(f) - Hz
Gain - dB
-90
-40
10
60
110
160
Phase(°) - deg
Phase
Gain
Figure 2-6. TPS54231EVM-372 Loop Response
2.7 Output Voltage Ripple
The TPS54231EVM-372 output voltage ripple is shown in Figure 2-7. The output current is the rated full load of 2
A and VIN = 15 V. The ripple voltage is measured directly across the output capacitors.
Figure 2-7. TPS54231EVM-372 Output Ripple
www.ti.com Test Setup and Results
SLVU263A – AUGUST 2008 – REVISED OCTOBER 2021
Submit Document Feedback
TPS54231 Step-Down Converter Evaluation Module User's Guide 7
Copyright © 2021 Texas Instruments Incorporated

2.8 Input Voltage Ripple
The TPS54231EVM-372 input voltage ripple is shown in Figure 2-8 . The output current is the rated full load of 2
A and VIN = 15 V. The ripple voltage is measured directly across the input capacitors.
Figure 2-8. TPS54231EVM-372 Input Ripple
2.9 Powering Up
The start-up waveforms are shown in Figure 2-9 and Figure 2-10. In Figure 2-9, the top trace shows VIN, and
the bottom trace shows VOUT. In Figure 2-10 , the top trace shows EN (enable) whereas the bottom trace shows
VOUT. In Figure 2-10, the input voltage is initially applied and the output is inhibited by using a jumper at J2 to tie
EN to GND. When the jumper is removed, EN is released. When the EN voltage reaches the enable-threshold
voltage of 1.25 V, the start-up sequence begins and the internal reference voltage begins to ramp up at the
internally set rate toward 0.8 V and the output voltage ramps up to the externally set value of 3.3 V. The input
voltage for these plots is 15 V and there is no load.
Figure 2-9. TPS54231EVM-372 Start-Up Relative to VIN
Test Setup and Results www.ti.com
8TPS54231 Step-Down Converter Evaluation Module User's Guide SLVU263A – AUGUST 2008 – REVISED OCTOBER 2021
Submit Document Feedback
Copyright © 2021 Texas Instruments Incorporated

Figure 2-10. TPS54231EVM-372 Start-up Relative to Enable
2.10 Eco-mode Operation
At light load currents, the TPS54231 is designed to operate in pulse skipping Eco-mode. When the peak inductor
current is lower than 100 mA typical, the device enters Eco-mode.
Figure 2-11 shows Eco-mode operation, channel 1(C1) shows the output voltage while channel 2(C2) shows the
switching node (PH).
Figure 2-11. TPS54231EVM–372 Eco–mode Operation
2.11 Thermal Characteristics
This section shows a thermal image of the TPS54231EVM-372 running at 28 V input and 2 A load. These are
the worst case conditions for maximum power loss. There is no air flow and the ambient temperature is 25°C.
The peak temperature of the IC (85.8°C) is well below the maximum recommended operating condition listed in
the datasheet of 150°C.
www.ti.com Test Setup and Results
SLVU263A – AUGUST 2008 – REVISED OCTOBER 2021
Submit Document Feedback
TPS54231 Step-Down Converter Evaluation Module User's Guide 9
Copyright © 2021 Texas Instruments Incorporated

Figure 2-12. TPS54231EVM-372 Thermal Image
Test Setup and Results www.ti.com
10 TPS54231 Step-Down Converter Evaluation Module User's Guide SLVU263A – AUGUST 2008 – REVISED OCTOBER 2021
Submit Document Feedback
Copyright © 2021 Texas Instruments Incorporated