RENT

Enable _ Voltage

VIH _ EN 1

RENB

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Setup

where

•

VIH_EN is 2.2 V (typ)

(1)

PG – Testpoint— is used to monitor the power good flag. This flag indicates whether the output voltage

has reached its regulation point. This pin is an open-drain output that requires a pullup resistor to

the appropriate logic voltage (any voltage less than 14 V). A pre-installed resistor RPG1 of 100 k

Ω

is tied to the PG pin and brought out to the PG_PULL UP test point.

PG_PULL UP – Testpoint— is the top connection of the pre-assembled 100-k

Ω RPG1 pullup resistor that

ties directly to the open-drain PG pin. Supply an appropriate voltage to this test point, or tie it

directly to the VOUT test point to observe the PG flag operation.

BIAS – Testpoint— is used to monitor the BIAS voltage. A pre-installed capacitor of 4.7 µF is connected

from the BIAS pin to ground (GND). This node is connected to VOUT through a zero Ohm resistor

pre-installed on the bottom layer, labeled (RBIAS).

SYNC – Testpoint — is the input terminal for an optional external input clock to the converter. The

external clock frequency must be between 200 kHz and 2.2 MHz, if used. A pulldown resistor of

100 k

Ω (RSYNC) is installed on the EVM.

SW – Testpoint— is used to monitor the voltage on the switch pin and the switching frequency of the

voltage regulator. Remove this test point before making any electromagnetic interference (EMI)

measurements.

VSUPPLY – Edge Connector pin #9— is used to supply the input voltage through an on board LC filter (if

one is needed for conducted EMI/EMC measurement). The Lin and Cd component pads are

located on the bottom side of the EVM. Please refer to the EVM schematic for initial suggestion of

component values.

2

Setup

Set the input voltage (VIN) range for the converter between the operating voltage range of 3.5 V to 36 V. If

a load is driven, it should be applied to the VOUT terminal and should not exceed the maximum load

current of 3 A.

3

Operation

For proper operation of the LM43603, VIN, GND, and VOUT should be properly configured as stated

above. In this configuration, the device will start up when power is applied and the output voltage of the

regulator (VOUT) will come up to the proper value. The default setting for output voltage of the

LM43603EVM is 3.3V. Other output voltages can be set by replacing the feedback pin resistor dividers

RFBT and RFBB; please consult the datasheet for proper selection of these resistor values.

The default frequency for the LM43603EVM is 500 kHz. If other frequencies are desired, within the

frequency range of 200 kHz and 2.2 MHz, the RT resistor value can be changed. Please consult the

datasheet for proper selection of the RT resistor. You must change inductor (L_36_V_HC) and total output

capacitance for proper control loop operation.

3

SNVU388 – March 2014

LM43603EVM User’s Guide

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