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1 Setup
This section describes the test points and
connectors on the EVM and how to properly connect,
set up, and use the LMQ66430-Q1 EVM.
1.1 Test Points
The test points on the board can be used to
connect to the input of a power supply and output load for the EVM. See Figure 1-1 for typical test setup. The functions of the test point connections are:
Vin_EMI — Input supply to EVM including an EMI filter. Connect to a
suitable input supply. Connect at this point for EMI tests.
GND_EMI — Ground connection for the input supply
Vin — Input supply to the IC. Can be connected to a digital multimeter to
measure the input voltage after EMI filter.
VOUT — Output voltage test point of EVM. Can be connected to a desired
load.
GND — Ground test points
PG — This test point is connected to the PGOOD pin from the IC. Can be
tied to an external supply through a pullup resistor or left open.
SYNC — In a MODE/SYNC trim part, this test point is connected to
the SYNC pin of the IC. This test point can also be connected to an external
clock to synchronize the IC. Make sure the RT resistor is not installed when
applying a synchronous clock input. If RMOD is installed, JMODE/SYNC jumper must
not short pin 2 to either adjacent pins while applying a synchronous clock
input. For evaluating RT trim parts, see the JMODE/SYNC jumper
description in Section 1.2.
Vcc — This test point is
connected to the Vcc pin of the IC.
AGND— This test point represents the analog ground test point and is
connected to the ground plane.
JMODE/SYNC — Use this jumper to select the mode of operation in a
MODE/SYNC trim part. Connecting a
jumper between pin 1 and 2 sets the IC operation to PFM (pulse frequency
modulation) mode for a higher efficiency at light load. A jumper between pin 2
and pin 3 causes the IC to operate in FPWM (forced pulse width modulation) mode.
By default, the jumper is connected between pin 1 and 2. Pin 1 is indicated by
the dot on the PCB. When evaluating RT trim parts this jumper can be used
to set the switching frequency as long as RMOD is populated and RT is not
populated. With RMOD populated, connecting a jumper between pin 1 and 2 sets the
switching frequency to 2.2 MHz while connecting the jumper between pin 2 and 3
sets the switching frequency to 1 MHz. If the RT resistor is used to set the
switching frequency then RMOD should be depopulated, effectively removing the
JMODE/SYNC jumper.
JEN — This jumper allows
the ENABLE input to be connected to VIN or GND. Connecting a jumper between pin
1 and 2 shorts the ENABLE input to VIN, enabling the part. Connecting a jumper
between pin 2 and 3 shorts the ENABLE input to GND, disabling the part. By
default, this jumper is left open because there is a pullup resistor RENT to VIN
to enable the IC.
JPGOOD — Use this jumper
to select how the PGOOD pin is connected. A jumper between pin 1 and 2 uses Vcc
as the pullup voltage for PGOOD. In this configuration, the PGOOD pin is pulled
up to Vcc through RPG when the output voltage is within regulation. Connecting a
jumper between pin 2 and 3 uses VOUT as the pullup voltage for PGOOD. By
default, this jumper is not populated.