Texas Instruments | TPS65310A-Q1 Efficiency (Rev. A) | Application notes | Texas Instruments TPS65310A-Q1 Efficiency (Rev. A) Application notes

Texas Instruments TPS65310A-Q1 Efficiency (Rev. A) Application notes
Application Report
SLVA610A – October 2013 – Revised November 2013
TPS65310A-Q1 Efficiency
Michael Wendt
ABSTRACT
The TPS65310A-Q1 device is a power management unit that meets the requirements of DSP-controlled
automotive systems (Advanced Driver Assistance Systems). The device integrates commonly-used
features, which reduces board space and system costs.
The device includes one high-voltage buck controller for pre-regulation, and two buck controllers and one
boost converter for post-regulation. A further integrated low-dropout regulator (LDO) rounds up the powersupply concept and offers a flexible system design with five independent voltage rails. The device offers a
low-power-state LPM0 with all rails turned off to reduce current consumption in case the system is
constantly connected to the battery line. All outputs are protected against overload and over temperature.
An external PMOS allows the device to sustain voltage transients up to 80 V as a protection feature. This
external PMOS protects the system in safety-critical applications if a rail shows a malfunction
(undervoltage, overvoltage, undercurrent, or overcurrent). Internal soft start ensures controlled startup for
all supplies. Each power supply output has an adjustable output voltage based on the external resistor
network settings. For more information, see the TPS65310A-Q1 data sheet, SLVSC15.
The efficiency of the buck and boost regulators is important for the efficiency and thermal design of the
system. This application report shows efficiency measurement results.
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Contents
Efficiency Test of TPS65310A-Q1 ........................................................................................
Efficiency Test Setup .......................................................................................................
2.1
Efficiency Test Setup of Buck1 ...................................................................................
2.2
Efficiency Test Setup of Buck2 and Buck3 .....................................................................
2.3
Efficiency Test Setup of BOOST .................................................................................
Application Data .............................................................................................................
Test Results .................................................................................................................
4.1
Buck1 Efficiency ....................................................................................................
4.2
Buck2 Efficiency ....................................................................................................
4.3
Buck3 Efficiency ....................................................................................................
4.4
BOOST Efficiency ..................................................................................................
Efficiency Test Summary ...................................................................................................
SLVA610A – October 2013 – Revised November 2013
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TPS65310A-Q1 Efficiency
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Efficiency Test of TPS65310A-Q1
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Efficiency Test of TPS65310A-Q1
The efficiency of a DC-DC converter is the output power divided by the input power and is typically
represented as a percentage. The TPS65310A-Q1 device has a pre-buck regulator, Buck1. This external
power supply (car battery) supplies the buck regulator. The output of the Buck1 regulator is the supply of
the regulators Buck2, Buck3, BOOST, and LDO.
The standard method is used to measure the efficiency of the Buck1 regulator. This method calculates the
efficiency by the standard way of measuring the input power and the output power. Because the Buck2,
Buck3, BOOST, and LDO are supplied from Buck1, more effort is required to measure input power.
Buck2, Buck3, BOOST, and LDO cannot be separated because the TPS65310A device is a safety device
and monitors to correct the function of all regulators. If one regulator shows a failure, the device will try to
start-up seven times, but because of failure, the device ends in LPM0 state. For more details, please see
the TPS65310A-Q1 data sheet.
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Efficiency Test Setup
To perform the test, the device is placed on the TPS65310AEVM (see the EVM user's guide, SLVU912).
2.1
Efficiency Test Setup of Buck1
An external lab supply, VPROG, supplies the board and device under test (DUT). The input current is
measured with an ammeter IIN. An additional voltmeter measures VIN to ensure the correct input voltage
measurement.
A source meter creates the load current IOUT. Another voltmeter measures the output voltage VOUT.
The efficiency of the input and output power was calculated using VIN, IIN, VOUT, and IOUT.
TPS65310AEVM_Rev_C
IIN
Buck1
VOUT
VPROG
IOUT
VIN
Buck2
Buck3
BOOST
Figure 1. Efficiency Test Setup of Buck1
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TPS65310A-Q1 Efficiency
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Efficiency Test Setup
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2.2
Efficiency Test Setup of Buck2 and Buck3
An external lab supply, VPROG, supplies the board and DUT. The input currents of Buck2 and Buck3 were
measured with a voltmeter across a shunt resistor and IIN was calculated. An additional voltmeter
measures VIN to ensure the correct input voltage measurement (see Figure 2 and Figure 3).
A source meter created the load current IOUT. Another voltmeter measured the output voltage VOUT.
The efficiency of the input and output power was calculated using the VIN, IIN, VOUT, and IOUT.
TPS65310AEVM_Rev_C
TPS65310AEVM_Rev_C
Buck1
Buck1
IIN
IIN
VIN
Buck3
VIN
Buck2
VOUT
VOUT
IOUT
Buck3
Buck2
BOOST
BOOST
Figure 2. Efficiency Test Setup of Buck2
IOUT
Figure 3. Efficiency Test Setup of Buck3
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3
Application Data
2.3
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Efficiency Test Setup of BOOST
An external lab supply, VPROG, supplies the board and DUT. The input current of BOOST was measured
with an voltmeter across a shunt resistor and IIN was calculated. An additional voltmeter measured VIN to
ensure the correct input voltage measurement (see Figure 4).
A source meter created the load current IOUT. Another voltmeter measured the output voltage VOUT.
The efficiency of the input and output power was calculated using the VIN, IIN, VOUT, and IOUT.
TPS65310AEVM_Rev_C
Buck1
IIN
BOOST
VIN
VOUT
IOUT
Buck3
Buck2
Figure 4. Efficiency Test Setup of BOOST
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Application Data
Board
Buck 1
Buck 2
Buck 3
BOOST
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TPS65310A-Q1 Efficiency
Used board: TPS65310AEVM_Rev_C
VBAT
5 V, 8.1 V, 10 V, 14 V, 18 V, 22 V, 26 V, 30 V, 34 V, 36 V, 37 V
VOUT
3.8 V
ILoad
0 to 2.5 A
VBAT
13.8 V
VOUT
3.3 V
ILoad
0 to 2.4 A
VBAT
13.8 V
VOUT
1.2 V
ILoad
0 to 2.4 A
VBAT
13.8 V
VOUT
5V
ILoad
0 to 0.3 A
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Test Results
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4
Test Results
4.1
Buck1 Efficiency
100
90
80
Efficiency (%)
70
60
50
VBAT = 5 V
VBAT = 10 V
VBAT = 18 V
VBAT = 26 V
VBAT = 34 V
VBAT = 37 V
40
30
20
10
0
0.0
0.3
0.6
0.9
1.2
VBAT = 8.1 V
VBAT = 14 V
VBAT = 22 V
VBAT = 30 V
VBAT = 36 V
1.5
1.8
2.1
2.4
2.7
Iload (A)
C001
Figure 5. Efficiency Results of Buck1
4.2
Buck2 Efficiency
100
90
80
Efficiency (%)
70
60
50
40
30
20
10
0
0.0
0.3
0.6
0.9
1.2
1.5
1.8
Iload (A)
2.1
2.4
C002
Figure 6. Efficiency Results of Buck2
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TPS65310A-Q1 Efficiency
5
Efficiency Test Summary
4.3
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Buck3 Efficiency
100
90
80
Efficiency (%)
70
60
50
40
30
20
10
0
0.0
0.3
0.6
0.9
1.2
1.5
1.8
2.1
Iload (A)
2.4
C003
Figure 7. Efficiency Results of Buck3
4.4
BOOST Efficiency
100
90
80
Efficiency (%)
70
60
50
40
30
20
10
0
0.00
0.04
0.08
0.12
0.16
0.20
0.24
Iload (A)
0.28
0.32
C004
Figure 8. Efficiency Results of BOOST
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Efficiency Test Summary
The efficiency of the TPS65310A-Q1 device was measured with the device placed on the TPS65310EVM.
The device operated within the specified supply-voltage range and specified load range. Results for every
convertor are shown in the preceding diagrams.
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TPS65310A-Q1 Efficiency
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Revision History
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Revision History
Changes from Original (October 2013) to A Revision .................................................................................................... Page
•
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•
•
•
Deleted Advanced Information banner from document .............................................................................
Changed reference to the TPS65381-Q1 and corresponding data sheet to the TPS65310A-Q1 and corresponding
datasheet ..................................................................................................................................
Changed hyperlink to TPS65381-Q1 data sheet to TPS65310A-Q1 datasheet .................................................
Changed reference to the TPS65381EVM and corresponding User's Guide to the TPS65310EVM and corresponding
User's Guide ..............................................................................................................................
Changed board name in the head row of the Application Data table from TPS65310_EMC_Rev_C to
TPS65310AEVM_Rev_C ................................................................................................................
Added -Q1 to TPS65310A device name where missing ............................................................................
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NOTE: Page numbers for previous revisions may differ from page numbers in the current version.
SLVA610A – October 2013 – Revised November 2013
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Revision History
7
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