Texas Instruments TPS53128 User manual

User’s Guide
TPS53128 Buck Controller Evaluation Module User's
Guide
ABSTRACT
The TPS53128EVM-620 evaluation module presents an easy-to-use reference design for a common dual-output
power supply using the TPS53128 controller in cost-sensitive applications.
Table of Contents
1 Introduction.............................................................................................................................................................................3
1.1 Description......................................................................................................................................................................... 3
1.2 Application..........................................................................................................................................................................3
1.3 Features............................................................................................................................................................................. 3
2 Electrical Performance Specifications................................................................................................................................. 4
3 Schematics..............................................................................................................................................................................5
4 Connector and Test Point Descriptions................................................................................................................................6
4.1 Enable Switches (SW1 and SW2)......................................................................................................................................6
4.2 Switching Frequency Select Switch (SW3)........................................................................................................................ 6
4.3 Test Point Descriptions.......................................................................................................................................................6
5 Test Setup................................................................................................................................................................................8
5.1 Equipment.......................................................................................................................................................................... 8
5.2 Recommended Setup........................................................................................................................................................ 8
6 Test Procedure...................................................................................................................................................................... 10
6.1 Start-Up Procedure.......................................................................................................................................................... 10
6.2 Line/Load Regulation and Efficiency Measurement Procedure....................................................................................... 10
6.3 Output Ripple Voltage Measurement Procedure..............................................................................................................10
6.4 Shutdown Procedure........................................................................................................................................................10
7 Performance Data and Typical Characteristic Curves.......................................................................................................11
7.1 Efficiency.......................................................................................................................................................................... 11
7.2 Line and Load Regulation.................................................................................................................................................11
7.3 Output Voltage Ripple...................................................................................................................................................... 12
7.4 Switch Node Waveforms..................................................................................................................................................12
8 EVM Assembly Drawings and Layout.................................................................................................................................13
9 Bill of Materials..................................................................................................................................................................... 17
10 Revision History................................................................................................................................................................. 18
List of Figures
Figure 3-1. TPS53128EVM-620 Schematic.................................................................................................................................5
Figure 4-1. Tip and Barrel Measurement for Output Voltage Ripple............................................................................................7
Figure 5-1. TPS53128EVM-620 Recommended Test Setup....................................................................................................... 9
Figure 7-1. Efficiency vs Load....................................................................................................................................................11
Figure 7-2. Efficiency vs Load....................................................................................................................................................11
Figure 7-3. Output Voltage vs Load........................................................................................................................................... 11
Figure 7-4. Output Voltage vs Load........................................................................................................................................... 11
Figure 7-5. Output Voltage Ripple............................................................................................................................................. 12
Figure 7-6. Output Voltage Ripple............................................................................................................................................. 12
Figure 7-7. Switching Waveform................................................................................................................................................12
Figure 7-8. Switching Waveform................................................................................................................................................12
Figure 8-1. Top Assembly.......................................................................................................................................................... 13
Figure 8-2. Bottom Assembly.................................................................................................................................................... 14
Figure 8-3. Top Layer.................................................................................................................................................................14
Figure 8-4. Bottom Layer........................................................................................................................................................... 15
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Figure 8-5. Internal Layer 1....................................................................................................................................................... 15
Figure 8-6. Internal Layer 2....................................................................................................................................................... 16
List of Tables
Table 2-1. TPS53128EVM-620 Electrical and Performance Specifications.................................................................................4
Table 4-1. TPS53128EVM-620 Test Points Description.............................................................................................................. 6
Table 9-1. TPS53128EVM-620 Bill of Materials.........................................................................................................................17
Trademarks
D-CAP2™ is a trademark of Texas Instruments.
All trademarks are the property of their respective owners.
Trademarks www.ti.com
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1 Introduction
1.1 Description
The TPS53128EVM-620 evaluation board provides the user with a convenient way to evaluate the TPS53128
dual D-CAP2™ mode control step-down controller in a realistic cost-sensitive application. Providing both a low
core-type 1.05-V and I/O type 1.8-V output at up to 4 A from a loosely regulated 12-V (8-V to 22-V) source,
the TPS53128EVM-620 includes switches and test points to assist a user in evaluating the performance of the
TPS53128 controller in their application.
1.2 Application
• Digital television
• Set-top box
• DSL and cable modems
• Cost-sensitive digital consumer products
1.3 Features
• 8-V to 22-V input
• 1.05-V and 1.8-V output
• Up to 4 A per channel output
• 350-kHz psudeo-fixed frequency D-CAP2 mode control
• Independent enable switches for power-on/power-off testing
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2 Electrical Performance Specifications
Table 2-1. TPS53128EVM-620 Electrical and Performance Specifications
Parameter Notes and Conditions MIN TYP MAX UNIT
INPUT CHARACTERISTICS
VIN Input voltage 8 12 22 V
IIN Input current VIN = 12 V, IOUT1 = 4 A, IOUT2 = 4 A — 1.2 1.5 A
No load input current VIN = 12 V, IOUT = 0 A — 20 — mA
VIN_UVLO Input UVLO IOUT = 4 A 4.0 4.2 4.5 V
OUTPUT CHARACTERISTICS
VOUT1 Output voltage 1 VIN = 12 V, IOUT1 = 2 A — 1.05 — V
Line regulation VIN = 8 V to 22 V — — 1%
Load regulation IOUT1 = 0 A to 4 A — — 1%
VOUT1_rip Output voltage ripple VIN = 12 V, IOUT2 = 4 A — - 30 mVpp
IOUT1 Output current 1 VIN = 8 V to 22 V 0 4 A
VOUT2 Output voltage 2 VIN = 12 V, IOUT2 = 2 A — 1.80 — V
Line regulation VIN = 8 V to 22 V — — 1%
Load regulation IOUT2 = 0 A to 4 A — — 1%
VOUT2_rip Output voltage ripple VIN = 12 V, IOUT2 = 4 A — — 30 mVpp
IOUT2 Output current 2 VIN = 8 V to 22 V 0 4 A
SYSTEMS CHARACTERISTICS
FSW Switching frequency 200 350 400 kHz
ηpk1 Peak efficiency of output 1 VIN = 12 V — 87% —
η1 Full load efficiency of output 1 VIN = 12 V, IOUT1 = 4 A — 85% —
ηpk2 Peak efficiency of output 2 VIN = 12 V — 91% —
η2 Full load efficiency of output 2 VIN = 12 V, IOUT2 = 4 A — 90% —
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3 Schematics
+
+
+
For reference only. See Table 9-1 for specific values.
Figure 3-1. TPS53128EVM-620 Schematic
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4 Connector and Test Point Descriptions
4.1 Enable Switches (SW1 and SW2)
The TPS53128EVM-620 includes independent enable switches for each of the two outputs. When the switch
is in the DIS position, the channel is disabled and discharged per the internal discharge characteristics of the
TPS53128.
To enable VOUT1, place SW1 in the EN position. To enable VOUT2, place SW2 in the EN position.
4.2 Switching Frequency Select Switch (SW3)
The TPS53128EVM-620 does not populate SW3. When using TPS53128EVM-620 to evaluate the TPS53126
controller in the TSSOP package, SW3 can be populated to allow selection of the TPS53126 switching
frequency between 350 kHz and 700 kHz.
4.3 Test Point Descriptions
Table 4-1 lists the test points, their labels, uses, and where additional information is located.
Table 4-1. TPS53128EVM-620 Test Points Description
Test Point Label Use Section
TP1 SS1 Monitor Channel 1 Soft-Start Voltage Section 4.3.4
TP2 SS2 Monitor Channel 2 Soft-Start Voltage Section 4.3.4
TP3 GND Ground for Input Voltage Section 4.3.1
TP4 GND Ground for Channel 1 Output Voltage Section 4.3.2
TP5 SW1 Monitor Switching Node for Channel 1 Section 4.3.5
TP6 GND Ground for Channel 2 Output Voltage Section 4.3.3
TP7 VOUT2 Monitor Output Voltage for Channel 2 Section 4.3.3
TP8 VOUT1 Monitor Output Voltage for Channel 1 Section 4.3.2
TP9 VIN Monitor Input Voltage Section 4.3.1
TP10 VREG5 Monitor Output of VREG5 Regulator Section 4.3.6
TP11 SW2 Monitor Switching Node for Channel 2 Section 4.3.5
4.3.1 Input Voltage Monitoring (TP3 and TP9)
The TPS53128EVM-620 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. Measure all
input voltage between TP9 and TP3. To use TP9 and TP3, connect a voltmeter positive terminal to TP9 and
negative terminal to TP3.
4.3.2 Channel 1 Output Voltage Monitoring (TP4 and TP8)
The TPS53128EVM-620 provides two test points for measuring the voltage generated at the VOUT1 output by
the module. This allows the user to measure the actual output voltage without losses from output cables and
connectors. Measure all DC output voltage measurements between TP8 and TP4. To use TP8 and TP4, connect
a voltmeter positive terminal to TP8 and negative terminal to TP4.
For output ripple measurements, TP8 and TP4 allow a user to limit the ground loop area by using the tip and
barrel measurement technique shown in Figure 4-1.
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TP8 TP4
Metal Ground Barrel
Probe Tip
Figure 4-1. Tip and Barrel Measurement for Output Voltage Ripple
4.3.3 Channel 2 Output Voltage Monitoring (TP6 and TP7)
The TPS53128EVM-620 provides two test points for measuring the voltage generated at the VOUT2 output by
the module. This allows the user to measure the actual output voltage without losses from output cables and
connectors. Measure all DC output voltage between TP7 and TP6. To use TP7 and TP6, connect a voltmeter
positive terminal to TP7 and negative terminal to TP6.
For output ripple measurements, TP7 and TP6 allow a user to limit the ground loop area by using the tip and
barrel measurement technique shown in Figure 4-1.
4.3.4 Soft-Start Voltage Monitoring (TP1, TP2, and TP3)
The TPS53128EVM-620 provides two test points for measuring the soft-start ramp voltages. TP1 monitors the
soft-start ramp of Channel 1. TP2 monitors the soft-start ramp of Channel 2. To use TP1 or TP2, connect an
oscilloscope probe between TP1 or TP2 and TP3.
4.3.5 Switching Node Monitoring (TP3, TP5, and TP11)
The TPS53128EVM-620 provides two test points for measuring the switching node waveform voltages. TP5
monitors the switching node of Channel 1. TP2 monitors the switching node of Channel 2. To use TP5 or TP11,
connect an oscilloscope probe between TP5 or TP11 and TP3.
4.3.6 5-V Regulator Output Monitoring (TP3 and TP10)
The TPS53128EVM-620 provides a test point for measuring the output of the internal 5-V regulator. TP10
monitors the output voltage of the internal 5-V regulator. To use TP10, connect a voltmeter positive terminal to
TP10 and negative terminal to TP3.
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5 Test Setup
5.1 Equipment
5.1.1 Voltage Source
The input voltage source (VIN) is a 0-V to 25-V variable DC source capable of supplying 3.0 ADC minimum.
5.1.2 Meters
A1: 0 ADC to 5 ADC, ammeter
V1: VIN, 0-V to 25-V voltmeter
V2: VOUT1, 0-V to 2-V voltmeter
V3: VOUT2, 0-V to 2-V voltmeter
5.1.3 Loads
LOAD1 – One output load is an electronic load set for constant current mode capable of 0 ADC to 4 ADC at 1.05
VDC.
LOAD2 – The other output load is an electronic load set for constant current mode capable of 0 ADC to 4 ADC at
1.8 VDC.
5.1.4 Oscilloscope and Probe
The oscilloscope, analog or digital, must be set for AC-coupled measurement with 20-MHz bandwidth limiting.
Use 20-mV/division vertical resolution and 1.0-µse /division horizontal resolution for the output ripple voltage
test.
Oscilloscope probes with exposed conductive ground barrels are recommended.
5.1.5 Recommended Wire Gauge
VIN to J3 – The connection between the source voltage VIN and J1 of TPS53128EVM-620 can carry as much as
2 ADC. The minimum recommended wire size is AWG #16 with the total length of wire less than two feet (1-foot
input, 1-foot return).
J1 to LOAD1 and J2 to LOAD2 – The connection between J1 and LOAD1 and J2 and LOAD2 of
TPS53128EVM-620 can carry as much as 4 ADC each. The minimum recommended wire size is AWG #14
with the total length of wire less than two feet (1-foot input, 1-foot return).
5.1.6 Other Test Equipment
FAN – The TPS53128EVM-620 evaluation module includes components that can get hot to touch. Because this
EVM is not enclosed to allow probing of circuit nodes, a small fan capable of 200lfm–400 lfm is recommended to
reduce component temperatures when operating.
5.2 Recommended Setup
Figure 5-1 shows the recommended test setup to evaluate the TPS53128EVM-620. 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 also are recommended.
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LOAD1
1.05V @
4A
FAN
V2
+
-
LOAD2
1.8V @
4A V3
-
+
-
+
-
+
A1
-
+
V
VIN
V1
+-
Figure 5-1. TPS53128EVM-620 Recommended Test Setup
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6 Test Procedure
6.1 Start-Up Procedure
1. Prior to connecting the DC input source VIN, it is advisable to limit the source current from VIN to 3.0 ADC
maximum. Make sure VIN is initially set to 0 V.
2. Ensure LOAD1 and LOAD2 are set to constant current mode to sink 0 A before VIN is applied.
3. Verify SW1 and SW2 are in the desired position.
4. Place a fan as shown in Figure 5-1 and turn it on, making sure air is flowing across the EVM.
5. Increase VIN from 0 V to 12 VDC.
6.2 Line/Load Regulation and Efficiency Measurement Procedure
1. Set up the TPS53128EVM-620 per Section 5.2.
2. Start up the TPS53128EVM-620 per Section 6.1.
3. Adjust VIN to desired value between 8 VDC and 22 VDC.
4. Adjust LOAD1/LOAD2 to desired load between 0 A and 4 ADC.
5. Read input voltage, output voltage, and input current from V1, V2/V3, and A1, respectively.
6. Shut down TPS53128EVM-620 per Section 6.4.
6.3 Output Ripple Voltage Measurement Procedure
1. Set up the TPS53128EVM-620 per Section 5.2.
2. Start up the TPS53128EVM-620 per Section 6.1.
3. Adjust VIN to desired value between 8 VDC and 22 VDC.
4. Adjust LOAD1/LOAD2 to desired load between 0 A and 4 ADC.
5. Connect the oscilloscope probe to TP8 and TP4 for VOUT1, or TP7 and TP6 for VOUT2 as shown in Figure
4-1.
6. Measure output ripple.
7. Shut down the TPS53128EVM-620 per Section 6.4.
6.4 Shutdown Procedure
1. Set SW1 to DIS.
2. Set SW2 to DIS.
3. Decrease LOAD1 to 0 A and shut down LOAD1.
4. Decrease LOAD2 to 0 A and shut down LOAD2.
5. Decrease VIN to 0 V and shut down VIN.
6. Shut down the fan.
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