Texas Instruments TPS40400EVM-351 User manual

User’s Guide
TPS40400 Buck Controller Evaluation Module User's
Guide
Table of Contents
1 Introduction.............................................................................................................................................................................2
2 Description.............................................................................................................................................................................. 3
2.1 Typical Applications............................................................................................................................................................3
2.2 Features............................................................................................................................................................................. 3
3 Electrical Performance Specifications................................................................................................................................. 4
4 Schematic................................................................................................................................................................................5
5 Test Setup................................................................................................................................................................................6
5.1 Test and Configuration Software........................................................................................................................................ 6
5.2 Test Equipment.................................................................................................................................................................. 7
5.3 Recommended Test Setup.................................................................................................................................................8
5.4 USB Interface Adapter and Cable......................................................................................................................................9
6 EVM Configuration Using the Fusion GUI.......................................................................................................................... 11
6.1 Configuration Procedure...................................................................................................................................................11
6.2 Fusion GUI Screenshots.................................................................................................................................................. 11
7 Test Procedure...................................................................................................................................................................... 14
7.1 Line/Load Regulation and Efficiency Measurement Procedure....................................................................................... 14
7.2 Control Loop Gain and Phase Measurement Procedure................................................................................................. 14
7.3 List of Test Points............................................................................................................................................................. 15
7.4 Equipment Shutdown....................................................................................................................................................... 15
8 Performance Data and Typical Characteristic Curves...................................................................................................... 16
8.1 Efficiency..........................................................................................................................................................................16
8.2 Load Regulation............................................................................................................................................................... 16
8.3 Load Transients 1.............................................................................................................................................................17
8.4 Load Transient 2.............................................................................................................................................................. 17
8.5 Load Transient 3.............................................................................................................................................................. 18
8.6 Input and Output Ripple................................................................................................................................................... 18
8.7 Switch Node and HDRV...................................................................................................................................................19
8.8 VIN Turn On...................................................................................................................................................................... 19
8.9 Enable ON / OFF............................................................................................................................................................. 20
8.10 Turn ON with 92% (1.1V) Pre-bias.................................................................................................................................21
8.11 TPS40400EVM-351 Bode Plot (20-A output).................................................................................................................21
9 EVM Assembly Drawing and PCB Layout.......................................................................................................................... 22
10 List of Materials.................................................................................................................................................................. 26
11 Revision History..................................................................................................................................................................27
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1 Introduction
The TPS40400EVM-351 evaluation module (EVM) uses the TPS40400. The TPS40400 is a synchronous buck
controller that operates from a nominal 3.0-V to 20-V supply. This controller is an analog PWM controller that
allows programming and monitoring via the PMBus interface.
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2 Description
The TPS40400EVM-351 is designed to use a regulated 12-V bus to produce a regulated 1.2-V output at up to
20 A of load current. The TPS40400EVM-351 is designed to demonstrate the TPS40400 in a typical low-voltage
application while providing a number of test points to evaluate the performance of the TPS40400.
2.1 Typical Applications
• Smart Power Systems
• Power Supply Modules
• Communications Equipment
• Computing Equipment
2.2 Features
The TPS40400EVM-351 features:
• Regulated 1.2-V output, marginable and trimmable via the PMBus interface
• 20-A DC steady state output current
• Programmable soft start via the PMBus interface
• Programmable enable function via the PMBus interface
• Programmable over-current warning and fault limit along with the condition response via the PMBus interface
• Programmable over-voltage warning and fault limit along with the condition response via the PMBus interface
• Programmable high and low output margin voltages with a maximum range of +/-25% of nominal output
voltage
• Convenient test points for probing critical waveforms
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3 Electrical Performance Specifications
Table 3-1. TPS40400EVM-351 Electrical Performance Specifications
PARAMETER TEST CONDITIONS MIN TYP MAX UNITS
Input Characteristics
Voltage range VIN 8 12 14 V
Maximum input current VIN = 8 V, IO = 20 A 3.5 A
No load input current VIN = 14 V, IO = 0 A with auto skip mode 50 mA
Output Characteristics
Output voltage, VOUT 1.2 V
Output voltage regulation Line regulation(VIN = 8 V - 14 V) 0.5%
Load regulation(VIN = 12 V, Io = 0 A - 20 A) 0.5%
Output voltage ripple VIN = 12 V, IO = 20 A 30 mVpp
Output load current 0 20 A
Output over current 25
Systems Characteristics
Switching frequency 608 kHz
Peak efficiency VIN = 12 V, 1.2 V / 12 A, FSW = 300 kHz 89.6%
Full-load efficiency VIN = 12 V, 1.2 V / 20 A 88.2%
Operating temperature 25 °C
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4 Schematic
++
+
Figure 4-1. TPS40400EVM-351 Circuit Schematic
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5 Test Setup
5.1 Test and Configuration Software
In order to change any of the default configuration parameters on the EVM, it is necessary to obtain the TI
Fusion Digital Power Designer software.
5.1.1 Description
Fusion Digital Power Designer is the Graphical User Interface (GUI) used to configure and monitor the Texas
Instrument's TPS40400 power controller on this Evaluation Module (EVM). The application uses the PMBus
protocol to communicate with the controller over serial bus by way of a TI USB adapter (see Figure 5-3).
5.1.2 Features
Some of the tasks you can perform with the GUI include:
• Turn on or off the power supply output, either through the hardware control line or the PMBus operation
command.
• Monitor real-time data. Items such as input voltage, output voltage, output current, and warnings/faults are
continuously monitored and displayed by the GUI.
• Configure common operating characteristics such as VOUT, warning and fault thresholds, and switching
frequency.
This software is available for download at this location: http://focus.ti.com/docs/toolsw/folders/print/
fusion_digital_power_designer.html
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5.2 Test Equipment
5.2.1 Voltage Source
The input voltage source VIN should be a 0-V to 14-V variable DC source capable of supplying 10 ADC. Connect
VIN to J1 as shown in Figure 5-2.
5.2.2 Multimeters
• DMM 1: VIN at TP1 (VIN) and TP3 (GND).
• DMM 2: Input current measured across Shunt 1.
• DMM 3: VOUT at TP5 (VOUT) and TP17 (GND).
• DMM 4: Output current measured across Shunt 2.
5.2.3 Output Load
The output load should be an electronic constant-resistance mode load capable of 0 ADC to 25 ADC at 1.2 V. An
electronic constant-current load is also acceptable.
5.2.4 Oscilloscope
A digital or analog oscilloscope can be used to measure the output ripple. To measure output ripple, the
oscilloscope should be set for 1-MΩ impedance, 20-MHz bandwidth, AC coupling, 2-µs/division horizontal
resolution, 50-mV/division vertical resolution. As shown below in Figure 5-1, test points TP5 and TP17 can be
used to measure the output ripple voltage by placing the oscilloscope probe tip through TP5 and holding the
ground barrel to TP17. It is not recommended to use a leaded ground connection because this may induce
additional noise due to the large ground loop.
To measure other waveforms, adjust the oscilloscope as needed.
TP17TP5
Metal Ground Barrel
Probe Tip
Figure 5-1. Tip and Barrel Measurement for VOUT Ripple
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5.2.5 Fan
Some of the components in this EVM may exceed temperatures of 60°C during operation. A small fan capable of
200 LFM to 400 LFM is recommended to reduce component temperatures while the EVM is operating at heavy
loads. Exercise caution when touching the EVM while the fan is not running, and always exercise caution when
touching any circuits that may be live or energized.
5.2.6 Recommended Wire Gauge
Input Wires, VIN to J1 (12-V input): The minimum recommended wire size is 1x AWG #14 per input
connection, with the total length of wire less than 4 feet (2 feet input, 2 feet return). Maximum input current
should be in the order of 3.5 A.
Output Wires, J3 and J4 to Load: The minimum recommended wire size is 2x AWG #14, with the total length
of wire less than 4 feet (2 feet output, 2 feet return). Maximum output current should be in the order of 20 A.
5.3 Recommended Test Setup
Figure 5-2. TPS40400EVM-351 Recommended Test Set Up
Figure 5-2 is the recommended test set up to evaluate the TPS40400EVM-351. It is recommended to work at an
ESD-safe workstation while testing the EVM.
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5.4 USB Interface Adapter and Cable
Proper connection and polarity for USB interface adapter and cable.
Figure 5-3. TPS40400EVM-351 USB-To-GPIO Interface Adapter
5.4.1 Input Connections
1. Prior to connecting the DC input source VIN, it is advisable to limit the source current from VIN to 10 A
maximum. Make sure VIN is initially set to 0 V and connected as shown in Figure 5-2.
2. Connect a voltmeter DMM 1 at TP1 (VIN) and TP3 (GND) to measure the input voltage.
3. Connect a voltmeter DMM 2 across shunt to measure the input current.
5.4.2 Output Connections
1. Connect Load between J3 and J4; and set Load to constant-resistance mode to sink 0 ADC before VIN is
applied.
2. Connect a voltmeter DMM 3 at TP5 (VOUT) and TP17 (GND) to measure the output voltage.
3. Connect a voltmeter DMM 4 across shunt to measure the output current.
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5.4.3 Jumper Connections, JP1 and JP2
For most tests it is recommended to install both jumpers, JP1 and JP2 on their respective headers. This will
result in the remote sense points (the nodes at which the converter will regulate the output voltage) be located
near the output connectors J3 and J4. This configuration is best for most functional testing.
These jumpers can be arranged differently depending on the desired location of remote sense.
Note
The amount of voltage drop between the output connectors J3 and J4 and the remote sense points
is limited by the power dissipation in the internal remote sense resistors R7 and R18 (see schematic,
Figure 4-1).
These resistors are rated for 0.0625 W and are 49.9 Ω. This implies a remote sense voltage drop of no more
than 1.7 V in each of the +VE and –VE sense lines. Since this EVM is configured as a 1.2-V output, this will
likely not be the limiting factor, but caution is still advised because when remote sense is being utilized, the EVM
will attempt to regulate out a lossy load wire installation.
Note
The EVM may detect an Over-Voltage (OV) condition when remote sensing is being used, depending
on the configurable OV setting. Refer to Section 5.2.6 for wire gauge recommendations.
When remote sense is not being utilized and the sense points are defaulted to the output connector of the EVM,
the voltage drop in the load wires and the resulting reduced voltage applied to the electronic load may cause
erratic behavior with the electronic load. This is because many loads will not function properly at input voltages
lower than 1 V, which implies no more than 0.2-V drop combined in the load wires (+ and – load wires). Consult
the documentation of the electronic load being used.
5.4.4 Jumper Configurations
All Jumper selections should be made prior to applying power to the EVM. User can configure this EVM as per
following configurations.
Table 5-1. Jumper Configurations
JUMPERS JP1 AND JP2 DISCRETE SENSE WIRES RESULT USED FOR
Installed Do not use Default. Sense points are at the
output connectors of the EVM.
Most testing.
Not installed Not installed
Sense points are at the output
connectors of the EVM, but
through R7 and R18. Regulation
will be degraded.
Not usually desired in this
configuration.
Not installed
Installed and connected to the
output voltage at the location
where regulation is desired
Regulation will be at the far end
location of the added discrete
sense wires, usually desired to be
the point of load.
Tight regulation of output voltage
at a remote location, subject to
the limitations mentioned in 5.4.3.
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6 EVM Configuration Using the Fusion GUI
In order to configure the TPS40400 controller on the EVM, it is required to use the TI Fusion Digital Power
Designer software. It is necessary to have input voltage applied to the EVM prior to launching the software so
that the TPS40400 may respond to the GUI and the GUI can recognize the TPS40400. The default configuration
for the EVM is to start converting at an input voltage of 7 V, so in order to avoid any converter activity during
initial configuration, an input voltage less than 7 V should be applied.
6.1 Configuration Procedure
1. Adjust the input supply to provide 5 VDC, current limited to 1 A.
2. Apply the input voltage to the EVM. Refer to Figure 3: and Figure 4: for connections and test setup.
3. Launch the Fusion GUI software. Refer to the following screenshots in section 6.2 for more information.
4. Configure the EVM operating parameters as needed.
CAUTION
Some parameters can be configured to values that can result in erratic or unexpected behavior on
this EVM. Consult the TPS40400 datasheet for guidance in configuration of parameters.
6.2 Fusion GUI Screenshots
Figure 6-1. Screenshot 1: First Screen Upon Launching Fusion Software (Version may not match)
Figure 6-2. Screenshot 2: Fusion Successfully Recognizes the Device on EVM
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Figure 6-3. Screenshot 3: First Functional Screen, Configure Screen
Note
Most of these parameters are configurable. Consult the datasheet for the TPS40400 for details on
how to configure the device to achieve the desired performance.
CAUTION
Some parameters can be configured to values that can result in erratic or unexpected behavior on
this EVM. Consult the TPS40400 datasheet for guidance in configuration of parameters.
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Figure 6-4. Screenshot 4: “Monitor” Screen
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7 Test Procedure
7.1 Line/Load Regulation and Efficiency Measurement Procedure
1. Set up EVM as described in Section 5.3 and Figure 5-2.
2. Ensure load is set to draw 0 ADC.
3. Ensure all jumper configuration settings per Section 5.4.4.
4. Increase VIN from 0 V to 12 V. Using DMM 1 to measure input voltage.
5. Use DMM 3 to measure output voltage VOUT.
6. Vary Load from 0 ADC to 20 ADC, VOUT should be remain in load regulation.
7. Vary VIN from 8 V to 14 V, VOUT should remain in line regulation.
8. Decrease Load to 0 A
9. Decrease VIN to 0 V.
7.2 Control Loop Gain and Phase Measurement Procedure
TPS40400EVM-351 contains a 49.9-Ω series resistor in the feedback loop for loop response analysis.
1. Set up EVM as described in Section 5.3 and Figure 5-2.
2. Connect isolation transformer to test points marked TP13 and TP15.
3. Connect input signal amplitude measurement probe (channel A) to TP13. Connect output signal amplitude
measurement probe (channel B) to TP15.
4. Connect ground lead of channel A and channel B to TP14 and TP16.
5. Inject 40-mV or less signal through the isolation transformer.
6. Sweep the frequency from 100 Hz to 1 MHz with 10-Hz or lower post filter. The control loop gain and phase
margin can be measured.
7. Disconnect isolation transformer from bode plot test points before making other measurements (Signal
injection into feedback may interfere with accuracy of other measurements).
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7.3 List of Test Points
Table 7-1. TPS40400EVM-351 Test Point Functions
TEST POINTS NAME DESCRIPTION
TP1 VIN Input voltage
TP2 COMP Output of error amplifier
TP3 GND Ground
TP4 PGOOD Power good
TP5 VOUT Output voltage
TP6 SENSE + Positive remote sense
TP7 HDRV High-side driver output
TP8 SYNC Input, to synchronize oscillator to external frequency
TP9 TRACK Input to non-inverting side of error amplifier
TP10 SW Switch node
TP11 LDRV Low side driver output
TP12 PGND Power ground
TP13 CHA Input A for loop injection
TP14 SGND Signal ground
TP15 CHB Input B for loop injection
TP16 SGND Signal ground
TP17 GND Ground
TP18 SENSE - Negative remote sense
7.4 Equipment Shutdown
1. Reduce load current to zero amperes.
2. Reduce input voltage to zero volts.
3. Shut down FAN.
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8 Performance Data and Typical Characteristic Curves
Figure 8-1 through Figure 8-12 represent typical performance curves for TPS40400EVM-351.
8.1 Efficiency
80
82
84
86
88
90
92
94
96
0 2 4 6 8 10 12 14 16 18 20
Output Current (A)
Efficiency (%)
8−V Efficiency
12−V Efficiency
14−V Efficiency
G000
Figure 8-1.
8.2 Load Regulation
1.202
1.2023
1.2025
1.2027
1.203
1.2032
1.2035
1.2037
1.204
1.2043
1.2045
1.2047
1.205
1.2052
1.2055
1.2057
1.206
1.2063
1.2065
1.2067
1.207
0 2 4 6 8 10 12 14 16 18 20
Output Current (A)
Output Voltage (V)
8−V Regulation
12−V Regulation
14−V Regulation
G000
Figure 8-2.
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8.3 Load Transients 1
Table 8-1. Load Transients 1
VIN TRANSIENT TIMEBASE CH2 CH4
8 V 5 A - 11 A - 5 A 100 µs VOUT IOUT 5 A/div.
Figure 8-3.
8.4 Load Transient 2
Table 8-2. Load Transients 2
VIN TRANSIENT TIMEBASE CH2 CH4
8 V 5 A - 11 A 10 µs VOUT IOUT 5 A/div.
Figure 8-4.
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8.5 Load Transient 3
Table 8-3. Load Transients 3
VIN TRANSIENT TIMEBASE CH2 CH4
8 V 11 A -5 A 10 µs VOUT IOUT 5 A/div.
Figure 8-5.
8.6 Input and Output Ripple
Table 8-4. Input and Output Ripple
VIN TRANSIENT TIMEBASE CH1 CH2
14 V 20 A 400 ns VIN VOUT
Figure 8-6.
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8.7 Switch Node and HDRV
Table 8-5. Switch Node and HDRV
VIN TRANSIENT TIMEBASE CH1 CH2
8 V 20 A 40 ns HDRV SW
Figure 8-7.
8.8 VIN Turn On
Table 8-6. VIN Turn On
VIN TRANSIENT TIMEBASE EVENT CH1 CH2
8 V 10 A 1 ms VIN ON VIN VOUT
Figure 8-8.
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8.9 Enable ON / OFF
Table 8-7. Enable ON/OFF 1
VIN IOUT TIMEBASE EVENT CH1 CH2 CH3
8 V 10 A 400 µs CNTRL ON VOUT CNTRL VIN
Figure 8-9.
Table 8-8. Enable ON/OFF 2
VIN IOUT TIMEBASE EVENT CH1 CH2 CH3
8 V 10 A 20 µs CNTRL OFF CNTRL VIN VOUT
Figure 8-10.
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