Texas Instruments TPS40195 User manual

User’s Guide
TPS40195 Buck Controller Evaluation Module User's
Guide
Table of Contents
1 Introduction.............................................................................................................................................................................2
2 Description.............................................................................................................................................................................. 2
2.1 Applications........................................................................................................................................................................2
2.2 Features............................................................................................................................................................................. 2
3 TPS40195EVM Electrical Performance Specifications........................................................................................................3
4 Schematic................................................................................................................................................................................4
4.1 Test Points..........................................................................................................................................................................5
5 Test Setup................................................................................................................................................................................5
5.1 Equipment.......................................................................................................................................................................... 5
5.2 Equipment Setup................................................................................................................................................................7
6 Test Procedure........................................................................................................................................................................ 8
6.1 Line and Load Regulation.................................................................................................................................................. 8
6.2 Output Ripple Measurement (TP5, TP13)..........................................................................................................................8
6.3 Loop Analysis (TP7, TP8, TP10)........................................................................................................................................9
6.4 Disable (TP11) and Power Good (TP9)............................................................................................................................10
6.5 Switch Node (TP4) and SYNC (TP12)............................................................................................................................. 10
6.6 Equipment Shutdown....................................................................................................................................................... 10
7 TPS40195EVM Typical Performance Data and Characteristic Curves.............................................................................11
7.1 Line and Load Regulation.................................................................................................................................................11
7.2 Efficiency.......................................................................................................................................................................... 11
7.3 Output Voltage Ripple...................................................................................................................................................... 12
7.4 Transient Response......................................................................................................................................................... 12
7.5 Bode Plots........................................................................................................................................................................13
7.6 Test Point Waveforms...................................................................................................................................................... 14
8 EVM Assembly Drawings and Layout.................................................................................................................................15
9 List of Materials.....................................................................................................................................................................17
10 Revision History................................................................................................................................................................. 17
Trademarks
All trademarks are the property of their respective owners.
www.ti.com Table of Contents
SLUU297B – DECEMBER 2007 – REVISED JANUARY 2022
Submit Document Feedback
TPS40195 Buck Controller Evaluation Module User's Guide 1
Copyright © 2022 Texas Instruments Incorporated

1 Introduction
The TPS40195EVM evaluation module (EVM) is a synchronous buck converter providing a fixed 3.3-V output at
up to 20 A from a 12-V input bus. The EVM is designed to start up from a single supply, so no additional bias
voltage is required for start up. The module uses the TPS40195 4.5-V to 20-V Input, Voltage-Mode, Synchrns
Buck Controller w/ PGOOD data sheet.
2 Description
The TPS40195EVM is designed to use a regulated 12-V bus (8 V to 20 V) to produce a regulated 3.3-V output
at up to 20 A of load current. TPS40195EVM is designed to demonstrate the TPS40195 in a typical 12-V bus to
low-voltage application while providing a number of test points to evaluate the performance of the TPS40195 in a
given application.
2.1 Applications
• Non-isolated medium current point-of-load and low-voltage bus converters
• Networking equipment
• Telecommunications equipment
• Computer peripherals
• Digital set-top box
2.2 Features
• 8-V to 20-V input range
• 3.3-V fixed output
• 20-ADC steady state output current
• 300-kHz switching frequency
• 2-layer PCB with all components on top side
• Convenient test points for probing switching waveforms and non-invasive loop response testing
Introduction www.ti.com
2TPS40195 Buck Controller Evaluation Module User's Guide SLUU297B – DECEMBER 2007 – REVISED JANUARY 2022
Submit Document Feedback
Copyright © 2022 Texas Instruments Incorporated

3 TPS40195EVM Electrical Performance Specifications
Table 3-1. TPS40195EVM Electrical and Performance Specifications
PARAMETER CONDITIONS MIN NOM MAX UNITS
INPUT CHARACTERSTICS
VIN Input voltage 8 12 20 V
IIN Input current VIN = 8 V, IOUT = 20 A — 9 A
No load input current VIN = 12 V, IOUT = 0 A — 60 mA
VIN_ON Input turn-on voltage IOUT = 0 A to 20 A 6.3 7.2 8 V
VIN_HYS Input hysteresis IOUT = 0 A to 20 A 1.12
OUTPUT CHARACTERSTICS
VOUT Output voltage VIN = 12 V, IOUT = 20 A 3.23 3.3 3.36 V
Line regulation VIN = 8 to 20 V, IOUT = 20 A — — 0.5%
Load regulation VIN = 12 V, IOUT = 0 to 20 A — — 0.5%
VOUTpp Output voltage ripple VIN = 12 V, IOUT = 20 A — — 50 mVpp
IOUT Output current VIN = 8 V to 20 V 0 20 20 A
IOCP Output overcurrent inception point VIN = 12 V 20.5 — —
TRANSIENT RESPONSE
ΔI Load step 20 A to 4 A to 20 A — 16 — A
Load slew rate — 1 — A/μsec
Over shoot — 300 — mV
Settling time — 20 — μs
SYSTEMS CHARACTERSTICS
FSW Switching frequency 240 300 360 kHz
ηpk Peak efficiency VIN = 12 V, IOUT = 0 to 20 A — 95% —
η Full load efficiency VIN = 12 V, IOUT = 20 A — 92% —
Top Operating temperature range VIN = 8 to 20 V, IOUT = 0 to 20 A, with
fan — 25 — °C
www.ti.com TPS40195EVM Electrical Performance Specifications
SLUU297B – DECEMBER 2007 – REVISED JANUARY 2022
Submit Document Feedback
TPS40195 Buck Controller Evaluation Module User's Guide 3
Copyright © 2022 Texas Instruments Incorporated

4 Schematic
8.0 to 20V
+
+
+ +
GND
VOUT
VIN
GND
+
3.3V @20A
+ +
+
Figure 4-1. TPS40195EVM Schematic for Reference Only, See Table 9-1 List of Materials for Specific
Values
Schematic www.ti.com
4TPS40195 Buck Controller Evaluation Module User's Guide SLUU297B – DECEMBER 2007 – REVISED JANUARY 2022
Submit Document Feedback
Copyright © 2022 Texas Instruments Incorporated

4.1 Test Points
Table 4-1. Test Points Available on the TPS40195EVM
TEST POINT NAME DESCRIPTION
TP1 VIN Measure the input voltage at this point.
TP2 GND Ground connection for input voltage measurements
TP3 Soft Start Monitor the soft start capacitor voltage.
TP4 Switch Node Monitor the switch node voltage.
TP5 VOUT Measure the output voltage and ripple at this point, see Section 6.1.
TP6 GND Ground connection for output voltage measurements
TP7 CHA Input A for loop analysis, see Section 6.3.
TP8 CHB Input B for loop analysis, see Section 6.3.
TP9 Power Good Monitor power good signal at this point, see Section 6.4.
TP10 GND General ground connection
TP11 DISABLE Short TP11 to TP2 to disable the TPS40195 controller, see Section 6.4.
TP12 SYNC Inject square wave synchronizing pulse here, see Section 6.5.
TP13 GND Used for output ripple test with TP5, see Section 6.2.
5 Test Setup
5.1 Equipment
5.1.1 Voltage Source
VIN: The input voltage source (VIN) should be a 0-V to 20-V variable DC source capable of 20 ADC.
5.1.2 Meters
A1: 0 ADC to 20 ADC, ammeter
V1: VIN, 0-V to 20-V voltmeter
V2: VOUT, 0-V to 5-V voltmeter
5.1.3 Loads
LOAD1: The output load (LOAD1) should be an electronic constant current mode load capable of 0 ADC to 20
ADC at 3.3 V.
5.1.4 Oscilloscope
Oscilloscope: A digital or analog oscilloscope can be used to measure the ripple voltage on VOUT. It is
also used to monitor various test points around the EVM. Section 6 describes test procedure for these
measurements. For ripple measurements it is not recommended to use the leaded ground connection supplied
with the oscilloscope. This can induce additional noise due to the large ground loop area.
5.1.5 Signal Generator
A signal generator can be used to synchronous the EVM to a higher switching frequency. See Section 6 for
details on doing this.
5.1.6 Recommended Wire Gauge
VIN to J1: The connection between the source voltage, VIN and J1 of the EVM can carry as much as 20 ADC.
The minimum recommended wire size is 2x AWG #16 with the total length of wire less than two feet (2-feet
input, 2-feet return).
J3 and J4 to LOAD1 (Power): The power connection between J2 of the EVM and LOAD1 can carry as much
as 20 ADC. The minimum recommended wire size is 2x AWG #16, with the total length of wire less than two feet
(1-foot output, 1-foot return).
www.ti.com Schematic
SLUU297B – DECEMBER 2007 – REVISED JANUARY 2022
Submit Document Feedback
TPS40195 Buck Controller Evaluation Module User's Guide 5
Copyright © 2022 Texas Instruments Incorporated

5.1.7 Other
Fan: This evaluation module includes components that can get hot to the touch, because this EVM is not
enclosed to allow probing of circuit nodes, a small fan capable of 200 LFM to 400 LFM is required to reduce
component surface temperatures to prevent user injury. The EVM should not be left unattended while powered.
The EVM should not be probed while the fan is not running.
Test Setup www.ti.com
6TPS40195 Buck Controller Evaluation Module User's Guide SLUU297B – DECEMBER 2007 – REVISED JANUARY 2022
Submit Document Feedback
Copyright © 2022 Texas Instruments Incorporated

5.2 Equipment Setup
Shown in Figure 5-1 is the basic test setup recommended to evaluate the TPS40195EVM. Please note that
although the return for J1 and J4 are the same, the connections should remain separate as shown in Figure 5-1.
1. Working at an ESD workstation, make sure that any wrist straps, bootstraps, or mats are connected
referencing the user to earth ground before power is applied to the EVM. Electrostatic smock and safety
glasses should also be worn.
2. Prior to connecting the DC input source, VIN, it is advisable to limit the source current from VIN to 20-A
maximum. Make sure VIN is initially set to 0 V and connected as shown in Figure 5-1.
3. Connect the ammeter A1 (0-A to 20-A range) between VIN and J1 as shown in Figure 5-1.
4. Connect voltmeter V1 to TP1 and TP2 as shown in Figure 5-1.
5. Connect LOAD1 to J3 and J4 as shown in Figure 5-1. Set LOAD1 to constant current mode to sink 0 ADC
before VIN is applied.
6. Connect voltmeter, V2 across TP5 and TP6 as shown in Figure 5-1.
7. Place Fan as shown in Figure 5-1 and turn on, making sure air is flowing across the EVM.
.
Oscilloscop
e
1M W, AC
20MHz
See figure 3 for tip
and barrel
measurement 3.3V
0 to 20A
LOAD1
+ -
V2
+-
V1
+-
0 to 20V
VIN
- +
A1
FAN
Figure 5-1. TPS40195EVM Recommended Test Setup
www.ti.com Test Setup
SLUU297B – DECEMBER 2007 – REVISED JANUARY 2022
Submit Document Feedback
TPS40195 Buck Controller Evaluation Module User's Guide 7
Copyright © 2022 Texas Instruments Incorporated

6 Test Procedure
6.1 Line and Load Regulation
1. Increase VIN from 0 V to 8 V.
2. Step LOAD1 from 0 A to 20 A.
3. Record, VIN, IIN, VOUT and IOUT for each LOAD1 step.
4. Step VIN from 8 V to 20 V.
5. Repeat 2 to 4 above for each VIN step.
6. See Section 6.6 for equipment shut down.
See Section 7.1 and Section 7.2 for typical line and load regulation curves and efficiency results.
6.2 Output Ripple Measurement (TP5, TP13)
1. Set up the EVM as described in Section 5.2 and Figure 5-1.
2. Set the oscilloscope to the following:
• 1-MΩ input impedance
• 20-MHz Bandwidth
• AC coupling
• 1-μs/div horizontal resolution
• 10-mV/div vertical resolution
3. Place the oscilloscope probe tip through TP5 and hold the ground barrel to TP13 as shown in Figure 6-1. For
a hands free approach, the loop in TP13 can be cut and opened to cradle the probe barrel. V2 can have to
be removed from these test points to allow the oscilloscope to be connected.
4. Increase VIN to 8 V.
5. Vary LOAD1 from 0 A to 20 A and observe the oscilloscope waveform.
6. Repeat step 5 for various VIN values up to 20 V.
7. See Section 6.6 for equipment shutdown.
See Section 7.3 for typical ripple voltage results
TP13TP5
Metal Ground Barrel
Probe Tip
Figure 6-1. Output Ripple Measurement - Tip and Barrel Using TP5 and TP13
Test Procedure www.ti.com
8TPS40195 Buck Controller Evaluation Module User's Guide SLUU297B – DECEMBER 2007 – REVISED JANUARY 2022
Submit Document Feedback
Copyright © 2022 Texas Instruments Incorporated

6.3 Loop Analysis (TP7, TP8, TP10)
The TPS40195EVM contains a 1.30-kΩ series resistor in the feedback loop to allow for matched impedance
signal injection into the feedback for loop response analysis.
1. Set up the EVM as described in Section 5.2 and Figure 5-1.
2. Connect a input signal amplitude measurement probe (Channel A) to TP7 as shown in Figure 6-2.
3. Connect a output signal amplitude measurement probe (Channel B) to TP8 as shown in Figure 6-2.
4. Connect the ground lead of Channel A and Channel B to TP10 as shown in Figure 6-2.
5. Inject 30-mV or less signal across R11 (TP7 and TP8) through an isolation transformer.
6. Sweep frequency from 100 Hz to 1 MHz with 10 Hz or lower post filter.
7. Control loop gain can be measured by 20 × Log (ChannelB/ChannelA).
8. Control loop phase is measured by the phase difference between Channel A and Channel B.
9. Disconnect Isolation transformer from TP7 and TP8 before making other measurements (signal injection into
feedback may interfere with accuracy of other measurements).
10. See Section 6.6 for equipment shutdown.
See Section 7.5 for typical bode plots and transient performance of this EVM.
3.3V
0 to 20A
LOAD1
+-
V2
+-
V1
+-
0 to 20V
VIN
-+
A1
Network
Analyzer
CHA CHB
FAN
Figure 6-2. Control Loop Measurement Setup
www.ti.com Test Procedure
SLUU297B – DECEMBER 2007 – REVISED JANUARY 2022
Submit Document Feedback
TPS40195 Buck Controller Evaluation Module User's Guide 9
Copyright © 2022 Texas Instruments Incorporated

6.4 Disable (TP11) and Power Good (TP9)
The TPS40195EVM defaults to the Enabled state.
1. Set up the EVM as described in Section 5.2 and Figure 5-1.
2. Using a four-channel oscilloscope monitor TP11, TP9, and TP5.
3. Increase VIN to 8 V.
4. Set LOAD1 to 10 A.
5. Short TP11 to TP2. Output should drop to zero.
6. Remove short. Output should return to regulation.
7. Repeat steps 4 and 5 above for various VIN and LOAD1 combinations.
8. See Section 6.6 for equipment shutdown.
See Section 7.6 for typical disable and power good performance.
6.5 Switch Node (TP4) and SYNC (TP12)
1. Set up the EVM as described in Section 5.2 and Figure 5-1.
2. Use the oscilloscope to monitor TP4. Set the oscilloscope to the following:
• 1-MΩ input impedance
• 20-MHz Bandwidth
• AC coupling
• 1-μs/div horizontal resolution
• 5-V/div vertical resolution
3. Increase VIN to 12 V.
4. Set LOAD1 to 10 A.
5. Vary LOAD1 and observe the oscilloscope.
6. Vary VIN and observe the oscilloscope.
7. Set the signal generator to 360 kHz and pulse shape per Figure 6-1.
8. Connect the signal generator to TP12.
9. Monitor TP12 and TP4 with the oscilloscope.
10. Vary signal generator frequency from 360 kHz to 400 kHz.
11. See Section 6.6 for equipment shutdown.
2.5V < VINH < 6.0V
VINL< 0.5V
T < 1/(1.2 x FSW)
TF< 100ns
Time
Volts
Figure 6-3. Typical TPS40195EVM SYNC Signal. The TPS40195 Synchronizes on the Falling Edge.
6.6 Equipment Shutdown
1. Shut down the oscilloscope.
2. Shut down LOAD1.
3. Shut down VIN.
4. Shut down the fan.
Test Procedure www.ti.com
10 TPS40195 Buck Controller Evaluation Module User's Guide SLUU297B – DECEMBER 2007 – REVISED JANUARY 2022
Submit Document Feedback
Copyright © 2022 Texas Instruments Incorporated