Texas instruments LMQ61460EVM-400K User Manual
User's Guide
SNVU698–March 2020
LMQ61460EVM-400K User's Guide
The LMQ61460-Q1 evaluation module (EVM) is designed to help customers evaluate the performance of
the LMQ61460-Q1 synchronous step-down voltage converter. This EVM implements the LMQ61460-Q1 in
a 14-pin wettable flanks Hotrod™ package, as shown in Table 1. It is capable of delivering 5-V output
voltage and up to 6-A load current switching at 400 kHz with exceptional efficiency and output accuracy in
a very small solution size. The EVM provides multiple power connectors and test points. In addition to an
optimized EMI board layout, the LMQ61460-Q1 uses integrated bypass capacitors which results in great
EMI performance.
Table 1. Device and Package Configurations
CONVERTER IC PACKAGE
U1 LMQ61460-Q1 14-pin wettable flanks Hotrod package 4.0 mm × 3.5 mm × 1.0 mm
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Figure 1. LMQ61460EVM-400K Top View
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LMQ61460EVM-400K User's Guide
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Introduction
Contents
1 Introduction ................................................................................................................... 2
2 Quick Start Guide............................................................................................................ 3
3 Detailed Descriptions........................................................................................................ 4
4 Schematic..................................................................................................................... 5
5 Board Layout ................................................................................................................. 8
6 LMQ61460EVM-400K Board Test Results.............................................................................. 11
7 Bill of Materials ............................................................................................................. 13
Trademarks
Hotrod is a trademark of Texas Instruments.
All other trademarks are the property of their respective owners.
1 Introduction
1.1 LMQ61460-Q1 Synchronous Step-Down Voltage Converter
The LMQ61460-Q1 is an easy-to-use synchronous step-down DC/DC converter capable of delivering up
to 6 A of load current from a supply voltage ranging from 3 V to 36 V. The LMQ61460-Q1 provides
exceptional efficiency and output accuracy in a very small solution size. The LMQ61460-Q1 is capable of
delivering 6 A of load current and implements peak current mode control. The following are additional
features that provide both flexible and easy-to-use solutions for a wide range of applications:
• Adjustable switching frequency (RT)
• Synchronization to an external clock (CLK jumper)
• FPWM variant (LMQ61460AFS) (IC swap)
• Power-good flag (PG jumper)
• Precision enable (EN jumper with RENT and RENB resistors)
Automatic frequency foldback at light load and optional external bias improve efficiency over the entire
load range. The device requires few external components and has a pinout designed for optimal EMI and
thermal performance. Protection features include the following:
• Thermal shutdown
• Input undervoltage lockout
• Cycle-by-cycle current limiting
• Hiccup short-circuit protection
For a quick reference, Figure 2 shows the pin configuration of the LMQ61460-Q1.
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CAUTION
Caution Hot surface.
Contact may cause burns.
Do not touch.
3.5 mm
4 mm
BIAS
CBOOT
RBOOT
EN/
SYNC
RESET
VIN1
VIN2
PGND1
PGND2
SW
FB
AGND
VCC
RT
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Figure 2. LMQ61460-Q1 Pin Configuration (Top View)
1.2 LMQ61460-Q1 Evaluation Module
The LMQ61460EVM-400K is populated with the LMQ61460AASQRJRRQ1 which automatically reduces
frequency at light loads (PFM - pulse frequency modulation). This IC can be replaced with the
LMQ61460AFSQRJRRQ1 for a constant switching frequency across load (FPWM - forced pulse width
modulation).
Introduction
2 Quick Start Guide
1. Connect the voltage supply between the VIN and GND connectors or between VIN_EMI and
GND_EMI to include the on-board input filter in the input path. Use short and thick gauge wires to
minimize inductance and IR drop. Note that sense points for VINand V
2. Connect the load of the converter between VOUT and GND connectors using short and thick wires.
3. Set the supply voltage at an appropriate level between 6 V to 36 V. The 6 V minimum input voltage
ensures enough head room for V
supply to an appropriate level to supply needed current and protection.
4. Turn on the power supply. With the default configuration, the EVM powers up and provides V
to 5 V.
5. Monitor the output voltage with sense points. The maximum load current is 6 A with the LMQ61460Q1. Note that the maximum output current may need to derate if ambient temperature is high,
especially if device is operated at higher frequency, that is 2.2 MHz.
See Figure 4 for connector locations.
are provided.
OUT
to equal 5 V at a 6 A load current. Set the current limit of the
OUT
equal
OUT
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Detailed Descriptions
3 Detailed Descriptions
This section describes the connectors on the EVM and how to properly connect, set up, and use the EVM.
See Figure 1 for a top view of the EVM.
VOUT —Output voltage of the converter
VOUT connectors connect to the power inductor and output capacitors. Connect the load between
the VOUT connector and the GND connector to provide load current. Connect the loading device to
the board with short and thick wires to handle the large DC output current.
GND —Ground of the converter
The GND is connected to the PGND and AGND pins of the device as well as the ground of the
input and output capacitors. The GND connections next to VIN, VIN_EMI, and VOUT connectors
are meant for current return path for the supply voltage and load, respectively. Connectors are
provided in pairs to allow easy and accurate sensing of voltages. Connect to supply and load
grounds with short and thick wires. Other GND connectors are for signal measurement and probing.
VIN— Input voltage to the converter
The VINconnector connects to the input capacitors and the VIN pins of the LMQ61460-Q1. Connect
the supply voltage from a power supply or a battery between VIN and GND connectors as power
input to the device. The input voltage (VIN) range must be higher than 3.9 V for the device to start
up and above 3 V to maintain operation. A VINhigher than 6 V provides a regulated 5-V output
voltage. Maximum VINis limited to 36 V to avoid damaging the device. The current limit on the
supply must be high enough to provide the needed supply current. The supply voltage must be
connected to the board with short and thick wires to handle the required input current at maximum
load current. If long cables are used to power up the board, damping must be provided by adding
CFLT3 and RFLT3 to avoid oscillation between the cable parasitic inductance and the existing lowESR ceramic capacitors.
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VIN_EMI —Low EMI option
If the input filter is required, connect the supply voltage between VIN_EMI and GND_EMI. The
supply voltage must be connected to the board with short and thick wires.
The input filter consists of the following: CF1, CF2, CF3, CF4, CF5, CF6, and L2. CD1, CD2, RD1,
and RD2 are provided to allow more options for filter optimization. To include the input filter in the
power path, connect the supply voltage between the VIN_EMI and GND_EMI connectors. The
output of the filter is connected to VIN, which is connected to the VINpins of the LMQ61460-Q1.
Conducted EMI arises from the operation of switching circuits.
GND_EMI —Ground return for the input filter
This is the current return path for the supply connected to VIN_EMI. It provides a short-loop
connection to the input filter capacitors to best filter the conducted noise generated from the PCB.
Use VIN_EMI and GND_EMI connection if input filter is used and conducted EMI test is desired.
CLK —For synchronization clock input
The CLK input connector is designed for external clock input to the EN/SYNC pin. Switching action
of the buck is synchronized to the external clock when it is present. The operation mode
automatically changes to forced PWM mode, maintaining a constant switching frequency over the
entire load range while the clock signal is present.
EN — To monitor the EN pin or control EN signal
This test point is used to monitor the voltage on the device EN pin. By default, the EN pin is
connected to the mid-point of an enable divider. Note that the lower resistor in this divider, RENB, is
not populated so the IC turns on by default. Populate RENB to adjust UVLO. Apply a voltage to EN
to externally enable or disable the device.
PG — To monitor the PGOOD/RESET pin
The PGOOD flag indicates whether the output voltage is within the regulation band. The RESET
pin (synonymous with PGOOD pin) of the device is an open-drain output and is pulled up to V
OUT
through a 100 k resistor. This pin pulls to GND when the output voltage is out of regulation.
4
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Vinj —For measuring AC response
A low value resistor, Rinj, is placed between VOUT and this node. The feedback divider of the
board is connected to this node. An AC signal is applied across Rinj when taking measurements for
bode plots.
VOUTS —VOUT sense
This connector is provided for measuring the output voltage accurately.
VINS —VIN sense
This connector is provided for measuring the input voltage accurately.
4 Schematic
The bill of materials is tabulated in Section 7. In addition, Figure 3 shows the corresponding schematic.
Schematic
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