Texas Instruments TPS51113 User manual

User’s Guide
TPS51113 Buck Controller Evaluation Module User's
Guide
Table of Contents
1 Introduction.............................................................................................................................................................................2
2 Description.............................................................................................................................................................................. 2
3 Typical Applications............................................................................................................................................................... 2
4 Features...................................................................................................................................................................................2
5 Electrical Performance Specifications................................................................................................................................. 2
6 Schematic................................................................................................................................................................................3
7 Test Setup................................................................................................................................................................................4
8 Test Procedure........................................................................................................................................................................ 6
9 Performance Data and Typical Characteristic Curves........................................................................................................ 7
10 EVM Assembly Drawing and PCB Layout........................................................................................................................ 10
11 List of Materials...................................................................................................................................................................11
12 References...........................................................................................................................................................................11
13 Revision History..................................................................................................................................................................11
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TPS51113 Buck Controller Evaluation Module User's Guide 1
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1 Introduction
The TPS51113-EVM evaluation module (EVM), is a high efficiency single phase synchronous buck converter
providing a fixed 1.2-V output at up to 25 A from a 12-V input bus. The EVM uses the TPS51113 synchronous
buck controller.
2 Description
The TPS51113-EVM is designed to use a regulated 12-V (8 V to 14 V) bus to produce a high current, regulated
1.2-V output at up to 25 A of the load current. The TPS51113-EVM is designed to demonstrate the TPS51113
in a typical low-voltage application while providing a number of test points to evaluate the performance of the
TPS51113.
3 Typical Applications
• High current system converters for server and desktop power
• Point of load non-isolated DC-DC converters for telecom and datacom application
4 Features
The TPS51113-EVM features include:
• 25-A DC steady state current
• Start-up into the pre-biased output
• 300-kHz switching frequency
• JP1 for enable function
• Convenient test points for probing critical waveforms and loop response testing
• Four-layer PCB with 2-oz. copper
• All components on the top layer
5 Electrical Performance Specifications
Table 5-1 gives the EVM performance specifications.
Table 5-1. Performance Specification Summary
SPECIFICATION TEST CONDITIONS MIN TYP MAX UNITS
INPUT CHARACTERISTICS
VIN Input voltage range 8 12 14 V
IIN(max) Maximum input current VIN = 8 V, IO = 25 A 4.3 A
IIN No load input current VIN = 14 V, IO = 0 A 100 mA
OUTPUT CHARACTERISTICS
VOUT Output voltage 1.2 V
VREG Output voltage regulation Line regulation 0.1%
Load regulation 0.3%
VRIPPLE Output voltage ripple VIN = 12 V, IO = 25 A 40 mVpp
Ouptut load current 0 25 A
Output overcurrent threshold 33 A
SYSTEMS CHARACTERISTICS
fSW Switching frequency 300 kHz
η Peak efficiency VIN = 12 V, VOUT = 1.2 V, IO = 18 A 89.19%
η Full load efficiency VIN = 12 V, VOUT = 1.2 V, IO = 25 A 88.57%
TAOperating ambient temperature 25 °C
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6 Schematic
S
W
COMP
CHB
CHA
GND PGN
D
PGND
VIN
ENABL
E
GND
LOOP INJECTION PGOOD
PGND
VOUT
PGND
Enable Notes:
1. No jumper on the JP1 to Enable the controller.
2. Jumper shorted on JP1 to disable the controller
Figure 6-1. TPS51113-EVM Schematic Diagram
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7 Test Setup
7.1 Test Equipment
7.1.1 Voltage Source
The input voltage source VIN should be a variable DC source between 0 V and 14 V, capable of supplying 10
ADC. Connect VIN to J1 as shown in Figure 7-2.
7.1.2 Multimeters
A voltmeter between 0 V and 15 V should be used to measure VIN at TP1 (VIN) and TP2 (GND). A voltmeter
between 0 V and 5 V for output voltage measurement at TP6 (VOUT) and TP8 (GND). A current meter between 0
A and 10 A (A1) as shown in Figure 7-2 is used for input current measurements.
7.1.3 Output Load
The output load should be an electronic constant resistance mode load capable of between 0 ADC and 30 ADC at
1.2 V.
7.1.4 Oscilloscope
A digital or analog oscilloscope can be used to measure the output ripple. The oscilloscope should be set for the
following:
• 1-MΩ impedance
• 20-MHz bandwidth
• AC coupling
• 2-μs/division horizontal resolution
• 50-mV/division vertical resolution
Test points TP6 and TP8 can be used to measure the output ripple voltage. Place the oscilloscope probe tip
through TP6 and rest the ground barrel on TP8 as shown in Figure 7-1. Using a leaded ground connection may
induce additional noise due to the large ground loop.
TP8TP6
Metal Ground Barrel
Probe Tip
Figure 7-1. Tip and Barrel Measurement for VOUT Ripple
7.1.5 Fan
Some of the components in this EVM may approach temperatures of 60°C during operating. A small fan capable
of 200–400 LFM is recommended to reduce component temperatures while the EVM is operating. The EVM
should not be probed while the fan is not running.
7.1.6 Recommended Wire Gauge
For VIN to J1 (12-V input), the recommended wire size is 1 × AWG #14 per input connection, with the total length
of wire less than four feet (2-feet input, 2-feet return). For J2 to LOAD, the minimum recommended wire size is 2
× AWG #14, with the total length of wire less than four feet (2-feet output, 2-feet return).
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7.2 Recommended Test Setup
Figure 7-2 is the recommended test set up to evaluate the TPS51113-EVM. 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.
EXAST
INSTRUMENTS
FAN
V1
A1
DC
source
+
-
Load
-
+
V2
-
+
-
-
+
+
Figure 7-2. TPS51113-EVM Recommended Test Setup
7.2.1 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 7-2.
2. Connect a voltmeter V1 at TP1(VIN) and TP2 (GND) to measure the input voltage.
7.2.2 Output Connections
1. Connect Load to J2 and set Load to constant resistance mode to sink 0 ADC before VIN is applied.
2. Connect a voltmeter V2 at TP6 (VOUT) and TP8 (GND) to measure the output voltage.
7.2.3 Other Connections
Place a fan as shown in Figure 7-2 and turn it on, making sure air is flowing across the EVM.
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8 Test Procedure
8.1 Line/Load Regulation and Efficiency Measurement Procedure
1. Ensure that the load is set to constant resistance mode and to sink 0 ADC.
2. Ensure that the jumper provided in the EVM shorts on JP1 before VIN is applied.
3. Increase VIN from 0 V to 12 V, using V1 to measure input voltage.
4. Remove the jumper on JP1 to enable the controller.
5. Vary load from between 0 ADC and 25 ADC. VOUT should be remain in load regulation.
6. Vary VIN from 8 V to 14 V. VOUT should remain in line regulation.
7. Put the jumper on JP1 to disable the controller.
8. Decrease the load to 0 A.
9. Decrease VIN to 0 V.
8.2 Control Loop Gain and Phase Measurement Procedure
The TPS51113-EVM contains a 20-Ω series resistor in the feedback loop for loop response analysis.
1. Set up the EVM as described in Section 8.1 and Figure 7-2.
2. Connect the isolation transformer to test points marked TP4 and TP3.
3. Connect an input signal amplitude measurement probe (channel A) to TP4.
4. Connect an output signal amplitude measurement probe (channel B) to TP3. Connect the ground lead of
channel A and channel B to TP9 and TP10.
5. Inject around 40-mV or less signal through the isolation transformer.
6. Sweep the frequency from 100 Hz to 1 MHz with a 10-Hz or lower post filter. The control loop gain and
phase margin can be measured.
7. Disconnect the isolation transformer from the bode plot test points before making other measurements
(Signal injection into feedback may interfere with accuracy of other measurements).
8.3 Test Points
Table 8-1. Test Point Functions
TEST POINTS NAME DESCRIPTION
TP1 VIN+ 12-V input
TP2 GND PGND for VIN
TP3 CHB Input B for loop injection
TP4 CHA Input A for loop injection
TP5 SW Monitor switch node voltage
TP6 VOUT VOUT
TP7 COMP Enable/COMP
TP8 GND PGND for VOUT
TP9 GND GND for loop measurement
TP10 PGND PGND
TP11 PGOOD Power Good
8.4 Equipment Shutown Procedure
1. Shut down the load.
2. Shut down VIN.
3. Shut down the fan.
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9 Performance Data and Typical Characteristic Curves
Figure 9-1 through Figure 9-8 present typical performance curves for the TPS51113-EVM.
0
75
70
24 6 8 10 12 14 16 18 20 22 24
85
80
95
90
IOUT – Output Current – A
h– Efficiency – %
Input
Voltage (V)
14
12
8
EFFICIENCY
vs
OUTPUT CURRENT
Figure 9-1. Efficiency
0
1.192
1.190
2 4 6 8 10 12 14 16 18 20 22 24 26
1.196
1.194
1.200
1.198
IOUT – Output Current – A
VOUT – Output Voltage – V
OUTPUT VOLTAGE
vs
OUTPUT CURRENT
Input
Voltage (V)
14
12
8
Figure 9-2. Load Regulation
Figure 9-3. Bode Plot
Figure 9-3 shows the bode plot where:
• VIN = 12 V
• VOUT = 1.2 V
• IOUT = 25 A
• Crossover frequency = 39.72 kHz
• Phase margin = 70.53°
• Gain margin = 23.13 dB
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Figure 9-4. 0-A to 10-A Load TransientX X Figure 9-5. Output RippleX X
Figure 9-6. Enable Turn-OffX X Figure 9-7. Enable Turn-OnX X
Figure 9-8. Switching Node
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.
.
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10 EVM Assembly Drawing and PCB Layout
Figure 10-1 through Figure 10-6 show the design of the TPS51113-EVM printed circuit board. The EVM has
been designed using four layers on a 2-oz. copper circuit board.
EXAST
INSTRUMENTS
Figure 10-1. Top Layer Assembly Drawing (Top
View)
Figure 10-2. Bottom Assembly Drawing (Bottom
View)
Figure 10-3. Top Copper (Top View) Figure 10-4. Internal Layer 1 (Top View)
Figure 10-5. Internal Layer 2 (Top View) Figure 10-6. Bottom Copper (Top View)
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