Texas Instruments LM63635EVM User manual

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LM63635EVM EVM User’s Guide
User's Guide
SNVU617–January 2020
LM63635EVM EVM User’s Guide
The Texas Instruments LM63635EVM evaluation module (EVM) helps designers evaluate the operation
and performance of the LM63635-Q1 buck regulator. The LM63635-Q1 is a family of easy-to-use
synchronous step-down DC/DC converters capable of driving up to 3.25 A of load current from an input
voltage of 3.5 V to 32 V. The LM63635EVM features a selectable output voltage of 3.3 V or 5 V and a
switching frequency of 400 kHz. See the LM636x5-Q1 3.5-V to 36-V, 1.5-A, and 2.5-A Automotive Step-
down Voltage Converter Data Sheet for additional features, detailed description, and available options.
The EVM options are found in Table 1.
Table 1. Device and Package Configurations
EVM DEVICE FREQUENCY/OUTPUT
CURRENT
LM63635EVM LM63635DQPWPRQ1 400 kHz / 3.25 A
Contents
1 Setup .......................................................................................................................... 3
2 Operation ..................................................................................................................... 6
3 Performance Curves ........................................................................................................ 6
4 Schematic..................................................................................................................... 7
5 Board Layout ................................................................................................................. 8
6 Bill of Materials ............................................................................................................. 12
List of Figures
1 EVM Board Connections.................................................................................................... 3
2 EVM Card Edge Connections.............................................................................................. 4
3 Jumper Locations............................................................................................................ 4
4 FRA Setup.................................................................................................................... 5
5 Efficiency Without Input Filter AUTO Mode, VOUT = 3.3V, fSW = 400 KHz............................................. 6
6 Efficiency Without Input Filter AUTO Mode, VOUT = 5 V, fSW = 400 KHz.............................................. 6

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LM63635EVM EVM User’s Guide
7 LM63635EVM Schematic................................................................................................... 7
8 Top View of EVM ............................................................................................................ 8
9 Bottom View of EVM ........................................................................................................ 9
10 EVM Top Copper Layer..................................................................................................... 9
11 EVM Mid Layer One ....................................................................................................... 10
12 EVM Mid Layer Two ....................................................................................................... 10
13 EVM Bottom Copper Layer ............................................................................................... 11
List of Tables
1 Device and Package Configurations ...................................................................................... 1
2 BOM for LM63635EVM.................................................................................................... 12
Trademarks
All trademarks are the property of their respective owners.

LOAD
POWER
SUPPLY
DMM
(+)
(-)
(+)
(-)
(-)
(+)
DMM
(+)
(-)
VIN
VOUT
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LM63635EVM EVM User’s Guide
1 Setup
This section describes the test points and connectors on the EVM and how to properly connect, set up,
and use the LM63635EVM. Either the test points on the top of the board or the card edge connector can
be used for connections. See Figure 1 for the top of board connections and Figure 2 for the card edge
connections. The following lists the functions of the connections:
VIN_EMI— Input supply to EVM. Connect to a suitable input supply. See the LM636x5-Q1 3.5-V to 36-V,
1.5-A, and 2.5-A Automotive Step-down Voltage Converter Data Sheet for input supply
requirements.
GND— System ground
VOUT— Output of EVM. Connect to desired load.
VOUTS— Output voltage sense connection (do not use for current; sense only)
VINS— Input voltage sense connection (do not use for current; sense only)
GNDS— Ground sense point for analog measurements (do not use for current; sense only)
Figure 1. EVM Board Connections

5V or 3.3V
Output Voltage
Selection Jumper
FPWM or Auto
Selection Jumper
GND VOUT
GNDS
VOS
TOP FRONT
BOTTOM FRONT
VIS
VINEMI
INPUT
SUPPLY LOAD
(+) (-) (-) (+)
(+)
(-)
DMMDMM
(-)(+)
(+)(-)
Filtered
VOUT *
(+) (-)
CM Choke
Input *
* = Optional Connections
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LM63635EVM EVM User’s Guide
Figure 2. EVM Card Edge Connections
1.1 Jumpers
See Figure 3 for jumper locations.
J1— This jumper allows the VOUT_SEL pin input to be connected to either VCC or GND for a fixed
output voltage selection of 3.3 V or 5 V, respectively. Alternatively, the jumper can be left open and
a RVOUTSEL can be populated with 10 kΩto have the part operate with an adjustable output voltage.
See the LM636x5-Q1 3.5-V to 36-V, 1.5-A, and 2.5-A Automotive Step-down Voltage Converter
Data Sheet for feedback resistor calculation.
J2— This jumper allows SYNC to be connected in this mode to either VCC or GND. When connected to
VCC, the part operates in forced pulse width modulation (FPWM) mode and when the SYNC pin is
connected to GND, the part operates in auto mode where pulse frequency modulation (PFM) is
engaged.
Figure 3. Jumper Locations

B
Signal
Injection
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network analyzer
^_/v‰µšš}
network analyzer
A
GND
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LM63635EVM EVM User’s Guide
1.2 Test Points
•VIN_EMI - Input supply to EVM. Connect to a suitable input supply. See the LM636x5-Q1 3.5-V to 36-
V, 1.5-A, and 2.5-A Automotive Step-down Voltage Converter Data Sheet for input supply
requirements.
•GND - System power ground
•VOUT - Power output of EVM. Connect to desired load.
•VOUTS - Output voltage sense connection. Connect to DMM. It is also used for frequency response
analyzer connection (do not use for current; sense only).
•VINS - Input voltage sense connection. Connect to DMM (do not use for current; sense only).
•GNDS - Ground sense point for analog measurements. Connect to DMM (do not use for current; sense
only).
•EN - Connection for external EN logic input. Connect controlling logic to EN test point for external
enable control.
•RESET - Connected to the RESET pin of the IC. It is used as a flag output. The reset function can be
monitored at this test point. Pullup resistor, RPULLUP, must be populated. A typical value for pullup
resistor is 100 kΩ.
•SYNC - Connected to the SYNC pin of the IC. Connection to an external clock or synchronization
signal enables the IC switching frequency to follow the synchronization signal.
•TPGND1, TPGND2 - System power ground
Figure 4. FRA Setup

Output Current (A)
Efficiency (%)
0.001 0.01 0.1 1 55
65
70
75
80
85
90
95
eff_
8V
13.5V
18V
24V
Output Current (A)
Efficiency (%)
0.001 0.01 0.1 1 55
70
75
80
85
90
95
100
eff_
8V
13.5V
18V
24V
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LM63635EVM EVM User’s Guide
2 Operation
Once the above connections are made and the appropriate jumpers are set, the EVM is ready to use. The
EN pin is pulled up to VIN with a 100-kΩresistor.
The output voltage of the EVM can be selected by the VOUT jumper to either 3.3 V or 5 V. Other values
of output voltage can be programmed by removing the jumper on J1 before powering on the device and
changing the value of RFBT and RFBB on the EVM. In addition, it is possible that the values of the inductor
and the output capacitance need to be changed. See the LM636x5-Q1 3.5-V to 36-V, 1.5-A, and 2.5-A
Automotive Step-down Voltage Converter Data Sheet for more information.
To us the RESET function, a pullup resistor is required. A place for this resistor is provided on the bottom
of the PCB. Values of 10 kΩto 100 kΩare appropriate. Be sure to limit the voltage on this pullup to less
than the specified Abs max for this pin.
The EVM is equipped with several EMI filter options. These are accessed through the edge connector as
shown in Figure 2. Refer to Figure 2,Figure 7, and Table 2 for details.
Loop gain measurements can be made using the setup shown in Figure 4.
The EVM has been designed for maximum flexibility regarding component selection. This allows the user
to place preferred components such as the inductor, the capacitors, or both, on the board and test the
performance of the regulator. This way the power supply system can be tested before committing the
design to production.
3 Performance Curves
Figure 5. Efficiency Without Input Filter
AUTO Mode, VOUT = 3.3V, fSW = 400 KHz
Figure 6. Efficiency Without Input Filter
AUTO Mode, VOUT = 5 V, fSW = 400 KHz

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4 Schematic
Figure 7. LM63635EVM Schematic

CAUTION
Caution Hot surface.
Contact may cause burns.
Do not touch.
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LM63635EVM EVM User’s Guide
5 Board Layout
Figure 8. Top View of EVM

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Figure 9. Bottom View of EVM
Figure 10. EVM Top Copper Layer

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LM63635EVM EVM User’s Guide
Figure 11. EVM Mid Layer One
Figure 12. EVM Mid Layer Two