Texas Instruments TPS54232EVM-415 User manual

User’s Guide
TPS54232 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
3 Board Layout.........................................................................................................................................................................10
3.1 Layout.............................................................................................................................................................................. 10
3.2 Estimated Circuit Area......................................................................................................................................................11
4 Schematic and Bill of Materials...........................................................................................................................................12
4.1 Schematic........................................................................................................................................................................ 12
4.2 Bill of Materials.................................................................................................................................................................13
5 Revision History................................................................................................................................................................... 13
List of Figures
Figure 2-1. TPS54232EVM-415 Efficiency.................................................................................................................................. 4
Figure 2-2. TPS54232EVM-415 Low Current Efficiency..............................................................................................................5
Figure 2-3. TPS54232EVM-415 Load Regulation....................................................................................................................... 5
Figure 2-4. TPS54232EVM-415 Line Regulation........................................................................................................................ 6
Figure 2-5. TPS54232EVM-415 Transient Response................................................................................................................. 6
Figure 2-6. TPS54232EVM-415 Loop Response........................................................................................................................ 7
Figure 2-7. TPS54232EVM-415 Output Ripple........................................................................................................................... 7
Figure 2-8. TPS54232EVM-415 Input Ripple.............................................................................................................................. 8
Figure 2-9. TPS54232EVM-415 Start-Up Relative to VIN ...........................................................................................................8
Figure 2-10. TPS54232EVM-415 Start-Up Relative to Enable....................................................................................................9
Figure 2-11. TPS54232EVM-415 Eco-mode Operation...............................................................................................................9
Figure 3-1. TPS54232EVM-415 Top-Side Layout..................................................................................................................... 10
Figure 3-2. TPS54232EVM-415 Bottom-Side Layout................................................................................................................ 11
Figure 3-3. TPS54232EVM-415 Top-Side Assembly.................................................................................................................11
Figure 4-1. TPS54232EVM-415 Schematic...............................................................................................................................12
List of Tables
Table 1-1. Input Voltage and Output Current Summary...............................................................................................................2
Table 1-2. TPS54232EVM-415 Performance Specification Summary.........................................................................................2
Table 1-3. Output Voltages Available...........................................................................................................................................3
Table 2-1. EVM Connectors and Test Points............................................................................................................................... 4
Table 4-1. TPS54232EVM-415 Bill of Materials.........................................................................................................................13
Trademarks
SWIFT™ is a trademark of Texas Instruments.
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All trademarks are the property of their respective owners.
1 Introduction
This user's guide contains background information for the TPS54232 as well as support documentation for
the TPS54232EVM-415 evaluation module (HPA415). Also included are the performance specifications, the
schematic, and the bill of materials for the TPS54232EVM-415.
1.1 Background
The TPS54232 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 TPS54232 regulator. The switching frequency is internally set at a nominal 1000 kHz.
The high-side MOSFET is incorporated inside the TPS54232 package along with the gate drive circuitry. The
low drain-to-source on resistance of the MOSFET allows the TPS54232 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 TPS54232
provides adjustable slow start and undervoltage lockout inputs. The absolute maximum input voltage is 30 V for
the TPS54232EVM-415.
Table 1-1. Input Voltage and Output Current Summary
EVM INPUT VOLTAGE RANGE OUTPUT CURRENT RANGE
TPS54232EVM-415 VIN = 5 V to 15 V 0 A to 2 A
1.2 Performance Specification Summary
A summary of the TPS54232EVM-415 performance specifications is provided in Table 1-2. Specifications are
given for an input voltage of VIN = 12 V and an output voltage of 2.5 V, unless otherwise specified. The
TPS54232EVM-415 is designed and tested for VIN = 5 V to 15 V. The ambient temperature is 25°C for all
measurements, unless otherwise noted.
Table 1-2. TPS54232EVM-415 Performance Specification Summary
SPECIFICATION TEST CONDITIONS MIN TYP MAX UNIT
VIN voltage range 5 12 15 V
Output voltage set point 2.5 V
Output current range VIN = 5 V to 15 V 0 2 A
Line regulation IO = 1 A, VIN = 5 V to 15 V ±0.02%
Load regulation VIN = 12 V, IO = 0.2 A to 2 A ±0.25%
Load transient response IO = 0.5 A to 1.5 A Voltage change –40 mV
Recovery time 400 μs
IO = 1.5 A to 0.5 A Voltage change 60 mV
Recovery time 400 μs
Loop bandwidth VIN = 12 V, IO = 1 A 36 kHz
Phase margin VIN = 12 V , IO = 1 A 54 °
Input ripple voltage IO = 2 A 160 mVpp
Output ripple voltage IO = 2 A 10 mVpp
Output rise time 6 ms
Operating frequency 1000 kHz
Maximum efficiency TPS54232EVM-415, VIN = 5 V, IO = 0.5 A 88.6%
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1.3 Modifications
These evaluation modules are designed to provide access to the features of the TPS54232. 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 TPS54232EVM-415 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 TPS54232EVM-415 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.
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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, 2.5 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 with VIN = 5 V, and then decreases as the load
current increases towards full load. Figure 2-1 shows the efficiency for the TPS54232EVM-415 at an ambient
temperature of 25°C.
V = 3.3 V
O
60
65
70
75
80
85
90
95
100
0 0.25 0.5 0.75 1 1.25 1.5 1.75 2
I - Output Current - A
O
Efficiency - %
V = 5 V
I
V = 12 V
I
V = 15 V
I
Figure 2-1. TPS54232EVM-415 Efficiency
Figure 2-2 shows the efficiency for the TPS54232EVM-415 at lower output currents between 0.02 A and 0.20 A
at an ambient temperature of 25°C.
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50
55
60
65
70
75
80
85
90
95
100
0 0.02 0.04 0.06 0.08 0.1 0.12 0.14 0.16 0.18 0.2
Efficiency - %
V = 8 V
I
V = 12 V
I
V = 15 V
I
I - Output Current - mA
O
Figure 2-2. TPS54232EVM-415 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 TPS54232EVM-415 is shown in Figure 2-3.
-0.1
-0.08
-0.06
-0.04
-0.02
0
0.02
0.04
0.06
0.08
0.1
0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 2
I - Output Current - A
O
Output Voltage Regulation - %
V = 5 V
I
V = 12 V
I
V = 15 V
I
Figure 2-3. TPS54232EVM-415 Load Regulation
Measurements are given for an ambient temperature of 25°C.
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2.4 Output Voltage Line Regulation
The line regulation for the TPS54232EVM-415 is shown in Figure 2-4.
-0.025
-0.02
-0.015
-0.01
-0.005
0
0.005
0.01
0.015
0.02
0.025
5 6 7 8 9 10 11 12 13 14 15
V - Input Voltage - V
I
I = 1 A
O
Output Regulation - %
Figure 2-4. TPS54232EVM-415 Line Regulation
2.5 Load Transients
The TPS54232EVM-415 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.
VOUT
IOUT 0.5 - 2 A STEP
t - Time - 2 ms/div
Figure 2-5. TPS54232EVM-415 Transient Response
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2.6 Loop Characteristics
The TPS54232EVM-415 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.
-60
-50
-40
-30
-20
-10
0
10
20
30
40
50
60
f - Frequency - Hz
-180
-150
-120
-90
-60
-30
0
30
60
90
120
150
180
Gain
Phase
Gain - dB
Phase - Deg.
10 100 1k 10k 100k 1M
Figure 2-6. TPS54232EVM-415 Loop Response
2.7 Output Voltage Ripple
The TPS54232EVM-415 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.
VOUT
PH
t - Time - 1 s/divm
Figure 2-7. TPS54232EVM-415 Output Ripple
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2.8 Input Voltage Ripple
The TPS54232EVM-415 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.
VIN
PH
t - Time - 1 s/divm
Figure 2-8. TPS54232EVM-415 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 VOUT ,
and the bottom trace shows VIN. In Figure 2-10 , the top trace shows VOUT whereas the bottom trace shows
the slow start voltage . 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 output ramps up at the externally set
rate toward the set value of 2.5 V. The input voltage for these plots is 12 V and there is no load.
VOUT
VIN
t - Time - 2 ms/div
Figure 2-9. TPS54232EVM-415 Start-Up Relative to VIN
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VOUT
SS
t - Time - 2 ms/div
Figure 2-10. TPS54232EVM-415 Start-Up Relative to Enable
2.10 Eco-mode Operation
At light load currents, the TPS54232 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. TPS54232EVM-415 Eco-mode Operation
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3 Board Layout
This section provides a description of the TPS54232EVM-415, board layout, and layer illustrations.
3.1 Layout
The board layout for the TPS54232EVM-415 is shown in Figure 3-1 through Figure 3-3. The topside layer of the
EVM is laid out in a manner typical of a user application. The top and bottom layers are 2-oz. copper.
The top layer contains the main power traces for VIN, VOUT, and VPHASE. Also on the top layer are connections
for the remaining pins of the TPS54232 and a large area filled with ground. The bottom layer contains ground
and a signal route for the BOOT capacitor. The top and bottom and internal ground traces are connected with
multiple vias placed around the board including ten vias directly under the TPS54232 device to provide a thermal
path from the top-side ground plane to the bottom-side ground plane.
The input decoupling capacitor (C1, C2 is not used) and bootstrap capacitor (C4) are all located as close to the
IC as possible. In addition, the voltage set-point resistor divider components are also kept close to the IC. The
voltage divider network ties to the output voltage at the point of regulation, the copper VOUT trace past the output
capacitor (C3, C8 is not used). For the TPS54232, an additional input bulk capacitor may be required, depending
on the EVM connection to the input supply.
Figure 3-1. TPS54232EVM-415 Top-Side Layout
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