Texas Instruments TPS40190EVM-001 User manual

User’s Guide
TPS40190 Buck Controller Evaluation Module User's
Guide
Table of Contents
1 Introduction.............................................................................................................................................................................2
1.1 Description......................................................................................................................................................................... 2
1.2 Applications........................................................................................................................................................................2
1.3 Features............................................................................................................................................................................. 2
2 TPS40190EVM-001 Electrical Performance Specifications................................................................................................ 2
3 Schematic................................................................................................................................................................................3
3.1 Adjusting Output Voltage (R1)............................................................................................................................................4
3.2 Adjusting Short Circuit Protection (R6).............................................................................................................................. 4
3.3 Disable (TP1 and SW1)..................................................................................................................................................... 4
4 Test Setup................................................................................................................................................................................5
4.1 Equipment.......................................................................................................................................................................... 5
4.2 Equipment Setup................................................................................................................................................................5
4.3 Start-Up/Shutdown Procedure........................................................................................................................................... 7
4.4 Control Loop Gain and Phase Measurement Procedure................................................................................................... 8
4.5 Equipment Shutdown......................................................................................................................................................... 8
5 TPS40190EVM Typical Performance Data and Characteristic Curves...............................................................................8
5.1 Efficiency............................................................................................................................................................................8
5.2 Line and Load Regulation.................................................................................................................................................. 9
6 EVM Assembly Drawings and Layout.................................................................................................................................10
7 List of Materials.....................................................................................................................................................................14
8 Revision History................................................................................................................................................................... 15
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All trademarks are the property of their respective owners.
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TPS40190 Buck Controller Evaluation Module User's Guide 1
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1 Introduction
The TPS40190EVM-001 evaluation module (EVM) is a synchronous buck converter providing a fixed 1.5-V
output at up to 10 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 TPS40190 reduced pin count synchronous
buck controller.
1.1 Description
The TPS40190EVM-001 is designed to use a regulated 12-V (10 V–14 V) bus to produce a high current,
regulated 1.5-V output at up to 10-A of load current. The TPS40190EVM-001 is design to demonstrate the
TPS40190 in a typical regulated bus to low-voltage application while providing a number of test points to
evaluate the performance of the TPS40190 in a given application. The EVM can be modified to support output
voltages from 0.9 V to 3.3 V by changing a single set resistor.
1.2 Applications
• Non-isolated medium current point of load and low voltage bus converters
• Networking equipment
• Telecommunications equipment
• DC power distributed systems
1.3 Features
• 10-V to 14-V input range
• 1.5-V fixed output, adjustable with single resistor
• 10 ADC steady state output current
• 300-kHz switching frequency (fixed by the TPS40190)
• Single main switch N-channel MOSFET and single synchronous rectifier N-channel MOSFET
• Double sided 3-inch × 3-inch PCB with all components on top side
• Active converter uses less than 1.2 square inches – 1.775 × 0.670
• Convenient test points for probing critical waveforms and non-invasive loop response testing
2 TPS40190EVM-001 Electrical Performance Specifications
Table 2-1. TPS40190EVM-001 Electrical and Performance Specifications
Parameter Notes and Conditions Min Typ Max Units
Input Characteristics
Input voltage range 10 14 V
Max input current VIN = 10 V, IOUT = 10 A 2 A
No-load input current VIN = 14 V, IOUT = 0 A 100 mA
Output Characteristics
Output voltage R6 = 6.49 k, R5 = 10 k 1.45 1.50 1.55 V
Output voltage regulation Line regulation (10 V < VIN < 14 V, IOUT = 5 A) 1 %
Load regulation (< 0 A < IOUT < 10 A, VIN = 12 V)
Output voltage ripple VIN = 14 V, IOUT = 10 A 25 50 mVpp
Output load current 0 10 A
Output over current 23 A
System Characteristics
Switching frequency 240 300 360 kHz
Peak efficiency VOUT = 1.5 V, 8 A < IOUT < 12 A
V12V_IN = 10 V 87
%V12V_IN = 12 V 85
V12V_IN = 14 V 83
Full load efficiency VOUT = 1.5 V, IOUT = 15 A
V12V_IN = 10 V 84
%V12V_IN = 12 V 83
V12V_IN = 14 V 81
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3 Schematic
Figure 3-1. TPS40190EVM-001 Power Stage/Control Schematic
Note
The schematic is for reference only. See Table 3-2 for specific values.
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3.1 Adjusting Output Voltage (R1)
The regulated output voltage can be adjusted within a limited range by changing the ground resistor in the
feedback resistor divider (R1). The output voltage is given by Equation 1.
VOUT = VVREF ×  R5+R1
R1(1)
where
• VVREF = 0.591 V
• R5 = 10 kΩ
Table 3-1 contains common values for R1 to generate popular output voltages. The TPS40190EVM-001 is stable
through these output voltages but the efficiency can suffer as the power stage is optimized for the 1.5-V output.
Table 3-1. Adjusting VOUT with R1
VOUT R1
3.3 V(1) 2.15 k
2.5 V(1) 3.09 k
2.25 V 3.57 k
2.0 V 4.22 k
1.8 V 4.87 k
1.5 V 6.49 k
1.2 V 9.76 k
(1) For output voltages greater than 2.5 V, change C11 to 330 μF, 4 V or higher PosCAP.
3.2 Adjusting Short Circuit Protection (R6)
The TPS40190 uses a selectable current limit for short circuit protection. The current limit is selected from three
levels by placing a resistor at R6. The TPS40190 compares the voltage drop across the high-side FET (VDD to
SW) to an internal reference voltage selected during start-up. The voltage levels are shown in Table 3-2.
Table 3-2. Adjusting VSCP with R6
VSCP R6
160 mV 3.9 k
320 mV OPEN
420 mV 12 k
The current before declaring short circuit protection can be determined by dividing the VSCP by the RDS(ON) of
the high-side FET (Q2).
3.3 Disable (TP1 and SW1)
The TPS40190EVM-001 provides both a Disable input (TP1) and a Disable switch (SW1) to allow the user to
evaluate the Enable Function of the TPS40190. When the switch is ON or TP1 is pulled high, Q1 pulls EN (U1
pin 1) to ground and disables the TPS40190 IC.
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4 Test Setup
4.1 Equipment
4.1.1 Voltage Source (V12V_IN)
The input voltage source (V12V_IN) should be a 0-V to 15-V variable DC source capable of 5 ADC. Connect
V12V_IN to J1 as shown in Table 3-2.
4.1.2 Meters
• A1: 0 ADC to 5 ADC, ammeter
• V1: V12_IN, 0-V to 15-V voltmeter
• V2: V1V5_OUT, 0-V to 5-V voltmeter
4.1.3 Loads (LOAD1)
The output load (LOAD1) should be an electronic constant current mode load capable of 0-ADC to 15 ADC at 1.5
V.
4.1.4 Oscilloscope
A digital or analog oscilloscope can be used to measure the ripple voltage on VOUT. The oscilloscope should be
set for the following to take output ripple measurements:
• 1-MW impedance
• 20-MHz bandwidth
• AC coupling
• 1-ms/division horizontal resolution
• 20-mV/division vertical resolution
TP 9 and TP 10 can be used to measure the output ripple voltage by placing the oscilloscope probe tip through
TP 9 and holding the ground barrel to TP 10 as shown in Figure 4-1. For a hands-free approach, the loop in TP
10 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
V12V_IN to J1
The connection between the source voltage, V12V_IN, and J1 of the TPS40190EVM-001 can carry as much as
3 ADC. The minimum recommended wire size is AWG #16 with the total length of wire less than four feet (2-feet
input, 2-feet return).
J2 to LOAD1 (Power)
The power connection between J2 of TPS40190EVM-001 and LOAD1 can carry as much as 15 ADC. The
minimum recommended wire size is 2× AWG #16, with the total length of wire less than four feet (2-feet output,
2-feet 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 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.
4.2 Equipment Setup
Figure 4-1 is the basic test setup recommended to evaluate the TPS40190EVM-001. Please note that although
the return for J1 and J2 are the same, the connections should remain separate as shown in Figure 4-1.
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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, V12V_IN, it is advisable to limit the source current from V12V_IN to
5.0-A maximum. Make sure V12V_IN is initially set to 0 V and connected as shown in Figure 4-1.
3. Connect the ammeter A1 (0-A to 5-A range) between V12V_IN and J1 as shown in Figure 4-1.
4. Connect voltmeter V1 to TP6 and TP7 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
V12V_IN is applied.
6. Connect voltmeter V2 across TP8 and TP11 as shown in Figure 4-1.
7. Connect an oscilloscope probe to TP9 and TP10 as shown in Figure 4-1Figure 3.
8. Place a fan as shown in Figure 4-1 and turn on, making sure air is flowing across the EVM.
4.2.2 Diagram
Figure 4-1. TPS40190EVM-001 Recommended Test Setup
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Figure 4-2. Output Ripple Measurement – Tip and Barrel Using TP9 and TP10
Figure 4-3. Control Loop Measurement Setup
4.3 Start-Up/Shutdown Procedure
1. Increase V12V_IN from 0 V to 10 VDC.
2. Vary LOAD1 from 0 ADC to 10 ADC.
3. Vary V12V_IN from 1- VDC to 14 VDC.
4. Decrease LOAD1 to 0 A.
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4.4 Control Loop Gain and Phase Measurement Procedure
1. Connect a 1-kHz to 1-MHz isolation transformer to TP2 and TP3 as shown in Figure 4-1.
2. Connect an input signal amplitude measurement probe (Channel A) to TP2 as shown in Figure 4-1.
3. Connect an output signal amplitude measurement probe (Channel B) to TP3 as shown in Figure 4-1.
4. Connect the ground lead of Channel A and Channel B to TP 4 as shown in Figure 4-1.
5. Inject 25-mV or less signal across R7 through an 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 × LOG CℎannelB
CℎannelA .
8. Control loop phase is measured by the phase difference between Channel A and Channel B.
9. Disconnect the isolation transformer from TP2 and TP3 before making other measurements (signal injection
into feedback can interfere with accuracy of other measurements).
4.5 Equipment Shutdown
1. Shut down the oscilloscope.
2. Shut down LOAD1.
3. Shut down V12V_IN.
4. Shut down FAN.
5 TPS40190EVM Typical Performance Data and Characteristic Curves
Figure 5-1 and Figure 5-2 present typical performance curves for the TPS40190EVM-001. Since the actual
performance data can be affected by measurement techniques and environmental variables, these curves are
presented for reference and can differ from actual field measurements.
5.1 Efficiency
Figure 5-1. TPS40190EVM-001 Efficiency, VIN = 10 V to 14 V, VOUT = 1.5 V, IOUT = 0 A to 10 A
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5.2 Line and Load Regulation
Figure 5-2. TPS40190EVM-001 Line and Load Regulation
www.ti.com TPS40190EVM Typical Performance Data and Characteristic Curves
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6 EVM Assembly Drawings and Layout
Figure 6-1 and Figure 6-4 show the design of the TPS40190EVM-001 printed circuit board. The EVM has
been designed using a double sided, 2-oz copper-clad circuit board 3.0-inch × 3.0-inch with all components
on the top side to allow the user to easily view, probe, and evaluate the TPS40190 control IC in a practical
application. Moving components to both sides of the PCB or using additional internal layers can offer additional
size reduction for space constrained systems.
Figure 6-1. TPS40190EVM-001 Component Placement (Viewed from Top)
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