Texas Instruments TPS54386EVM User manual

User’s Guide
TPS54x86 Step-Down Converter Evaluation Module User's
Guide
Table of Contents
1 Introduction.............................................................................................................................................................................2
1.1 Description......................................................................................................................................................................... 2
1.2 Applications........................................................................................................................................................................2
1.3 Features............................................................................................................................................................................. 2
2 TPS54386EVM Electrical Performance Specifications........................................................................................................3
3 Schematic................................................................................................................................................................................4
3.1 Sequencing Jump (JP3).....................................................................................................................................................5
3.2 Enable Jumpers (JP1 and JP2)......................................................................................................................................... 5
3.3 Test Point Descriptions.......................................................................................................................................................5
4 4 Test Set Up........................................................................................................................................................................... 7
4.1 Equipment.......................................................................................................................................................................... 7
4.2 Equipment Setup................................................................................................................................................................8
4.3 Start Up / Shut Down Procedure......................................................................................................................................10
4.4 Output Ripple Voltage Measurement Procedure..............................................................................................................10
4.5 Control Loop Gain and Phase Measurement Procedure................................................................................................. 10
4.6 Equipment Shutdown....................................................................................................................................................... 10
5 TPS54386EVM Typical Performance Data and Characteristic Curves.............................................................................11
5.1 Efficiency.......................................................................................................................................................................... 11
5.2 Line and Load Regulation................................................................................................................................................ 12
5.3 Output Voltage Ripple...................................................................................................................................................... 12
5.4 Switch Node..................................................................................................................................................................... 13
5.5 Control Loop Bode Plot (low line, VIN = 8 V).................................................................................................................... 13
6 EVM Assembly Drawings and Layout.................................................................................................................................14
7 List of Materials.....................................................................................................................................................................17
8 Revision History................................................................................................................................................................... 17
List of Figures
Figure 3-1. TPS54386EVM Schematic........................................................................................................................................4
Figure 4-1. TPS54386EVM Recommended Test Set-Up............................................................................................................ 8
Figure 4-2. Tip and Barrel Measurement Technique (output ripple measurement using TP3 and TP4 or TP18 and TP19)....... 9
Figure 4-3. Control Loop Measurement Setup............................................................................................................................ 9
Figure 5-1. TPS54386EVM Efficiency verse Load Current VIN =9.6-13.2 V, VOUT1 = 5.0 V IOUT1 = 0-2 A, VOUT2 = 3.3 V
IOUT2 = 0-2 A...........................................................................................................................................................................11
Figure 5-2. TPS54386EVM Output Voltage verse Load Current VIN =9.6-13.2 V, VOUT1 = 5.0 V IOUT1 = 0-2 A, VOUT2 =
3.3 V IOUT2 = 0-2 A.................................................................................................................................................................12
Figure 5-3. TPS54386EVM Output Voltage Ripple (VIN = 13.2 V, IOUT1 = IOUT2 = 2 A)............................................................. 12
Figure 5-4. TPS54386EVM Switching Waveforms VIN = 12 V, IOUT = 2 A Ch1: TP9 (SW1), Ch2: TP12 (SW2).......................13
Figure 5-5. TPS54386EVM Gain and Phase vs Frequency...................................................................................................... 13
Figure 6-1. TPS54386EVM Component Placement (viewed from top)..................................................................................... 14
Figure 6-2. TPS54386EVM Top Copper (viewed from top)....................................................................................................... 15
Figure 6-3. TPS54386EVM Bottom Copper (x-ray view from top).............................................................................................16
List of Tables
Table 2-1. Electrical Performance Specifications.........................................................................................................................3
Table 3-1. Test Point Descriptions............................................................................................................................................... 5
Table 7-1. TPS54386EVM List of Materials............................................................................................................................... 17
Trademarks
All trademarks are the property of their respective owners.
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1 Introduction
The TPS54386EVM evaluation module (EVM) is a dual non-synchronous buck converter providing fixed 5.0-V
and 3.3-V output at up to 2 A each 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 TPS54386 Dual Non-Synchronous
Buck Converter with Integral High-Side FET.
1.1 Description
TPS54386EVM is designed to use a regulated 12-V (+10% / -20%) bus to produce two regulated power rails, 5.0
V and 3.3 V at up to 2 A of load current each. TPS54386EVM is designed to demonstrate the TPS54386 in a
typical 12-V bus system while providing a number of test points to evaluate the performance of the TPS54386
in a given application. The EVM can be modified to other input or output voltages by changing some of the
components.
1.2 Applications
• Non-Isolated Low Current Point of Load and Voltage Bus Converters
• Consumer Electronics
• LCD TV
• Computer Peripherals
• Digital Set Top Box
1.3 Features
• 12-V (+10% / -20%) Input Range
• 5.0-V and 3.3-V Fixed Output Voltage, Adjustable with Resistor Change
• 2-ADC Steady State Output Current (3 A Peak)
• 600-kHz Switching Frequency (fixed by TPS54386)
• Internal Switching MOSFET and External Rectifier Diode
• Double Sided 2 Active Layer PCB (all components on top side, test point signals routed on internal layers)
• Active Converter Area Less than 1.8 Square Inches (0.89” x 1.97”)
• Convenient Test Points (used for probing switching waveforms and non-invasive loop response testing)
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2 TPS54386EVM Electrical Performance Specifications
Table 2-1. Electrical Performance Specifications
SYMBOL PARAMETER MIN TYP MAX UNITS
Input Characterstics
VIN Input coltage 9.6 12 13.2 V
IIN Input current VIN = nom, IOUT = max - 1.6 2.0 A
No load input current VIN = nom, IOUT = 0 A - 12 20 mA
VIN_UVLO Input UVLO IOUT = min to max 4.0 4.2 4.4 V
Output Characterstics
VOUT1 Output voltage 1 VIN = nom, IOUT = nom 4.85 5.0 5.15 V
VOUT2 Output voltage 2 VIN = nom, IOUT = nom 3.20 3.3 3.40
Line regulation VIN = min to max - - 1%
Load regulation IOUT = min to max - - 1%
VOUT_ripple Output voltage ripple VIN = nom, IOUT = max - - 30 mVpp
IOUT1 Output current 1 VIN = min to max 0 2.0
A
IOUT2 Output current 2 VIN = min to max 0 2.0
IOCP1
Output over current
Channel 1 VIN = nom, VOUT = VOUT1 - 5% 3.1 3.7 4.5
IOCP2
Output over current
Channel 2 VIN = nom, VOUT = VOUT2 - 5% 3.1 3.7 4.5
Systems Characterstics
FSW Switching frequency 510 630 750 kHz
ηpk Peak efficiency VIN = nom - 90% -
η Full load efficiency VIN = nom, IOUT = max - 85% -
Top Operating temperature
range VIN = min to max, IOUT = min to max 0 25 60 °C
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3 Schematic
+
Figure 3-1. TPS54386EVM Schematic
Note
For reference only, see Table 7-1, List of Materials for specific values.
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3.1 Sequencing Jump (JP3)
The TPS54386EVM provides a 3-pin, 100-mil header and shunt for programming the TPS54386’s sequencing
function. Placing the JP3 shunt in the left position connects the sequence pin to BP and sets the TPS54386
controller to sequence Channel 2 prior to Channel 1 when Enable 2 is activated. Placing the JP3 shunt in the
right position connects the sequence pin to GND and sets the TPS54386 converter to sequence Channel 1 prior
to Channel 1 when Enable 1 is activated. Removing the JP3 shunt disables sequencing and allows Channel 1
and Channel 2 to be enabled independently.
3.2 Enable Jumpers (JP1 and JP2)
TPS54386EVM provides separate 3-pin, 100-mil headers and shunts for exercising the TPS54386 Enable
functions. When JP3 is removed placing the JP1 shunt in the left position connects EN1 to ground and turns on
Output 1 and placing the JP2 shunt in the left position connects EN2 to ground and turns on Output 2.
When the JP3 shunt is in the LEFT position, placing the JP2 shunt in the left position connects EN2 to ground
and turns on first Output 2 and then Output 1.
When the JP3 shunt is in the RIGHT position, placing the JP1 shunt in the left position connects EN1 to ground
and turns on first Output 1 and then Output 2.
3.3 Test Point Descriptions
Table 3-1. Test Point Descriptions
TEST POINT LABLE USE SECTION
TP1 VIN Monitor input voltage Section 3.3.1
TP2 GND Ground for input voltage Section 3.3.1
TP3 VOUT1 Monitor VOUT1 Voltage Section 3.3.2
TP4 GND Ground for VOUT1 voltage Section 3.3.2
TP5 GND Ground for Channel B loop monitoring Section 3.3.3
TP6 CHB Channel B for loop monitoring Section 3.3.3
TP7 GND Ground for Channel A loop monitoring Section 3.3.3
TP8 CHA Channel A for loop monitoring Section 3.3.3
TP9 SW1 Monitor switching node of Channel 1 Section 3.3.4
TP10 GND Ground for switch node of Channel 1 Section 3.3.4
TP11 IC_GND Monitor device ground Section 3.3.5
TP12 SW2 Monitor switching node of Channel 2 Section 3.3.6
TP13 GND Ground for switch node of Channel 2 Section 3.3.6
TP14 CHA Channel A for loop monitoring Section 3.3.7
TP15 GND Ground for Channel A loop monitoring Section 3.3.7
TP16 CHB Channel B for loop monitoring Section 3.3.7
TP17 GND Ground for Channel B loop monitoring Section 3.3.7
TP18 VOUT2 Monitor VOUT2 voltage Section 3.3.8
TP19 GND Ground for VOUT2 voltage Section 3.3.8
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3.3.1 Input Voltage Monitoring (TP1 and TP2)
TPS54386EVM provides two test points for measuring the voltage applied to the module. This allows the
user to measure the actual module voltage without losses from input cables and connectors. All input voltage
measurements should be made between TP1 and TP2. To use TP1 and TP2, connect a voltmeter positive
terminal to TP1 and negative terminal to TP2.
3.3.2 Channel 1 Output Voltage Monitoring (TP3 and TP4)
TPS54386EVM provides two test points for measuring the voltage generated by the module. This allows the
user to measure the actual module output voltage without losses from output cables and connectors. All output
voltage measurements should be made between TP3 and TP4. To use TP3 and TP4, connect a voltmeter
positive terminal to TP3 and negative terminal to TP4. For Output ripple measurements, TP3 and TP4 allow a
user to limit the ground loop area by using the Tip and Barrel measurement technique shown in Figure 4-2. All
output ripple measurements should be made using the Tip and Barrel measurement.
3.3.3 Channel 1 Loop Analysis (TP5, TP6, TP7 and TP8)
TPS54386EVM contains a 51-Ω series resistor (R1) in the feedback loop to allow for matched impedance signal
injection into the feedback for loop response analysis. An isolation transformer should be used to apply a small
(30 mV or less) signal across R1 through TP6 and TP8. By monitoring the ac injection level at TP8 and the
returned ac level at TP6, the power supply loop response can be determined.
3.3.4 Channel 1 Switching Waveforms (TP9 and TP10)
TPS54386EVM provides a test point and a local ground connection (TP10) for the monitoring of the Channel 1
power stage switching waveform. Connect an oscilloscope probe to TP9 to monitor the switch node voltage for
Channel 1.
3.3.5 TPS54386 Device Ground (TP11)
TPS54386EVM provides a test point for the device ground. To measure the device pin voltages, connect the
ground of the oscilloscope probe to TP11.
3.3.6 Channel 2 Switching Waveforms (TP12 and TP13)
TPS54386EVM provides a test point and a local ground connection (TP13) for the monitoring of the Channel 1
power stage switching waveform. Connect an oscilloscope probe to TP12 to monitor the switch node voltage for
Channel 1.
3.3.7 Channel 2 Loop Analysis (TP14, TP15, TP16 and TP17)
TPS54386EVM contains a 51-Ω series resistor (R10) in the feedback loop to allow for matched impedance
signal injection into the feedback for loop response analysis. An isolation transformer should be used to apply a
small (30 mV or less) signal across R10 through TP14 and TP16. By monitoring the ac injection level at TP14
and the returned ac level at TP16, the power supply loop response can be determined.
3.3.8 Output Voltage Monitoring (TP18 and TP19)
TPS54386EVM provides two test points for measuring the voltage generated by the module. This allows the
user to measure the actual module output voltage without losses from output cables and connector losses. All
output voltage measurements should be made between TP18 and TP19. To use TP18 and TP19, connect a
voltmeter positive terminal to TP18 and negative terminal to TP19. For output ripple measurements, TP18 and
TP19 allow a user to limit the ground loop area by using the Tip and Barrel measurement technique shown in
Figure 4-2. All output ripple measurements should be made using the Tip and Barrel measurement.
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4 4 Test Set Up
4.1 Equipment
4.1.1 Voltage Source
VIN: The input voltage source (VIN) should be a 0-15 V variable dc source capable of 5 ADC. Connect VIN to J1
as shown in Figure 4-2.
4.1.2 Meters
• A1: 0-3 ADC, ammeter
• V1: VIN, 0-15 V voltmeter
• V2: VOUT1 0-6 V voltmeter
• V3: VOUT2 0-4 V voltmeter
4.1.3 Loads
LOAD1: The Output1 Load (LOAD1) should be an electronic constant current mode load capable of 0-2 ADC at
5.0 V
LOAD2: The Output2 Load (LOAD2) should be an electronic constant current mode load capable of 0-2 ADC at
3.3 V
4.1.4 Oscilloscope
Oscilloscope: A digital or analog oscilloscope can be used to measure the ripple voltage on VOUT. The
oscilloscope should be set for 1-MΩ impedance, 20-MHz bandwidth, ac coupling, 1-μs/division horizontal
resolution, 10-mV/division vertical resolution for taking output ripple measurements. TP3 and TP4 or TP18 and
TP19 can be used to measure the output ripple voltages by placing the oscilloscope probe tip through TP3 or
TP18 and holding the ground barrel to TP4 or TP19 as shown in Figure 4-2. For a hands free approach, the loop
in TP4 or TP19 can be cut and opened to cradle the probe barrel. Using a leaded ground connection may induce
additional noise due to the large ground loop area.
4.1.5 Recommended Wire Gauge
VIN to J1: The connection between the source voltage, VIN and J1 of HPA241 can carry as much as 5 ADC. The
minimum recommended wire size is AWG #16 with the total length of wire less than 4 feet (2 feet input, 2 feet
return).
J2 to LOAD1: The power connection between J2 of HPA241 and LOAD1 can carry as much as 2 ADC. The
minimum recommended wire size is AWG #18, with the total length of wire less than 2 feet (1 foot output, 1 foot
return).
J3 to LOAD2: The power connection between J3 of HPA241 and LOAD2 can carry as much as 2 ADC. The
minimum recommended wire size is AWG #18, with the total length of wire less than 2 feet (1 foot output, 1 foot
return).
4.1.6 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 200-400 lfm is recommended 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.
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4.2 Equipment Setup
Shown in Figure 4-1 is the basic test set up recommended to evaluate the TPS54386EVM. Please note that
although the return for J1, J2 and JP3 are the same system ground, the connections should remain separate as
shown in Figure 4-1
4.2.1 Procedure
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 5.0 A
maximum. Make sure VIN is initially set to 0 V and connected as shown in Figure 4-1.
3. Connect the ammeter A1 (0-5 A range) between VIN and J1 as shown in Figure 4-1.
4. Connect voltmeter V1 to TP1 and TP2 as shown in Figure 4-1.
5. Connect LOAD1 to J2 as shown in Figure 4-1. Set LOAD1 to constant current mode to sink 0 ADC before
VIN is applied.
6. Connect voltmeter, V2 across TP3 and TP4 as shown in Figure 4-1.
7. Connect LOAD2 to J3 as shown in Figure 4-1. Set LOAD2 to constant current mode to sink 0 ADC before
VIN is applied.
8. Connect voltmeter, V3 across TP18 and TP19 as shown in Figure 4-1.
9. Place fan as shown in Figure 4-1 and turn on, making sure air is flowing across the EVM.
4.2.2 Diagram
FAN
LOAD1
5.0V @
2A
-
+
V2
-
+
See Tip and Barrel
Measurement for Vout
ripple
Oscilloscope
1MW, AC
20mV / div
20MHz
LOAD2
3.3V @
2A
+
-
V3
-
+
V1
+
-
A1
-
+
V
VIN
Figure 4-1. TPS54386EVM Recommended Test Set-Up
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TP4 /
TP19
TP3 /
TP18
Metal Ground Barrel
Probe Tip
Tip and Barrel Vout ripple measurement
Figure 4-2. Tip and Barrel Measurement Technique (output ripple measurement using TP3 and TP4 or
TP18 and TP19)
FAN
V1
+
-
A1
-
+
V
VIN
LOAD1
5.0V @
2A
-
+
V2
-
+
LOAD2
3.3V @
2A
+
-
V3
-
+
Isolation
Transformer
Figure 4-3. Control Loop Measurement Setup
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4.3 Start Up / Shut Down Procedure
1. Increase VIN from 0 V to 12 VDC.
2. Vary LOAD1 from 0 – 2 ADC
3. Vary LOAD2 from 0 – 2 ADC
4. Vary VIN from 9.6 VDC to 13.2 VDC
5. Decrease VIN to 0 VDC
6. Decrease LOAD1 to 0 A.
4.4 Output Ripple Voltage Measurement Procedure
1. Increase VIN from 0 V to 12 VDC.
2. Adjust LOAD1 to desired load between 0 ADC and 2 ADC.
3. Adjust VIN to desired load between 9.6 VDC and 13.2 VDC.
4. Connect oscilloscope probe to TP3 and TP4 or TP18 and TP19 as shown in Figure 4-2.
5. Measure output ripple.
6. Decrease VIN to 0 VDC.
7. Decrease LOAD1 to 0 A.
4.5 Control Loop Gain and Phase Measurement Procedure
1. Connect 1 kHz to 1 MHz isolation transformer to TP6 and TP8 as show in Figure 4-3.
2. Connect input signal amplitude measurement probe (Channel A) to TP8 as shown in Figure 4-3.
3. Connect output signal amplitude measurement probe (Channel B) to TP6 as shown in Figure 4-3.
4. Connect ground lead of Channel A and Channel B to TP5 & TP7 as shown in Figure 4-3.
5. Inject 30 mV or less signal across R1 through isolation transformer.
6. Sweep frequency from 1 kHz to 1 MHz with 10 Hz or lower post filter.
7. Control loop gain can be measured by:
20 ChannelB LOG
ChannelA
æ ö
´ç ÷
è ø
8. Control loop phase is measured by the phase difference between Channel A and Channel B.
9. Control loop for Channel 2 can be measured by making the following substitutions.
a. Change TP6 to TP16
b. Change TP8 to TP14
c. Change TP5 to TP17
d. Change TP7 to TP15
10. Disconnect isolation transformer before making any other measurements (signal injection into feedback may
interfere with accuracy of other measurements).
4.6 Equipment Shutdown
1. Shut down oscilloscope
2. Shut down VIN
3. Shut down LOAD1
4. Shut down fan
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